JP2008184049A - Steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device capable of fully utilizing the merits of each of an electric power steering device and a hydraulic power steering device.
SOLUTION: In a region where the steering torque is small, the hydraulic power steering device 50 does not work effectively, but assist torque from the electric power steering device 40 is mainly transmitted to the steering amount transmitting means, and in a region where the steering torque is large, the electric power steering device. The assist torque from 40 and the assist force from the hydraulic power steering device 50 are transmitted to the steering amount transmitting means. For this reason, when the steering torque is small, fine integrated control can be performed by the electric power steering device 40. On the other hand, when a large steering torque such as stationary is required, both the electric power steering device 40 and the hydraulic power steering device 50 can be used. A large steering assist force can be obtained.
[Selection] Figure 1

Description

  The present invention relates to a steering device, and more particularly, to a steering device including a power steering device that generates a steering assist force for assisting a driver to steer a steering wheel.

  A steering device having a power steering device that generates a steering assist force for assisting a steering operation of a steering handle by a driver and transmits the steering assist force to a steering amount transmission means such as a steering shaft or a rack shaft connected to the steering handle. Generally popular. As this power steering device, hydraulic oil generated from a hydraulic pump such as a hydraulic pump is supplied to and discharged from the hydraulic actuator such as a power cylinder (supply / discharge), and the generated driving force is generated by the hydraulic actuator. A hydraulic power steering mechanism that uses a steering assist force and an electric power steering device that controls an electric motor by an electronic control unit or the like and uses a rotational driving force generated by the electric motor as a steering assist force have been put into practical use. Further, a vehicle equipped with both power steering devices by making good use of the characteristics of these two power steering devices has been proposed.

Patent Document 1 describes a system that uses both steering assistance by an electric power steering device and steering assistance by a hydraulic power steering device. Specifically, in Patent Document 1, steering assist is performed by an electric power steering device when the vehicle speed is higher than a predetermined value, and electric power steering device and hydraulic power steering device when the vehicle speed is lower than a predetermined value. The steering apparatus which assists steering by both of them is described. Japanese Patent Application Laid-Open No. 2004-228561 describes a technique for effectively operating an electric power steering device when an internal combustion engine is stopped while using an electric power steering device and a hydraulic power steering device together in a hybrid vehicle.
JP 2006-111141 A Japanese Patent Laid-Open No. 2004-090686

  The present invention makes full use of the merits of each of the electric power steering apparatus capable of fine output control and the hydraulic power steering apparatus that can be expected to have a large output, and can compensate for the demerits of each power steering apparatus. It is a technical problem to provide a steering device using both power steering devices.

  In order to achieve the above object, a feature of the present invention is that in a vehicle steering apparatus having a steering amount transmission means for transmitting a steering operation amount of a steering wheel to a steered wheel, a rotational driving force is generated and the generated rotational driving force is generated. An electric power steering apparatus comprising: an electric motor that transmits a steering assist force to the steering amount transmission means; and a control means that controls a rotational driving force generated by the electric motor based on a steering force acting on a steering handle; A hydraulic pump that discharges hydraulic oil, and a hydraulic actuator that generates driving force by supplying and discharging hydraulic oil discharged from the hydraulic pump, and transmits the generated driving force to the steering amount transmission unit as a steering assist force And a steering force that is provided in a main pipe that communicates the hydraulic pump and the hydraulic actuator and that acts on the steering handle is less than a predetermined value. A control valve mechanism that adjusts the amount of oil supplied from the hydraulic pump to the hydraulic actuator so that the hydraulic actuator does not generate a driving force but generates a driving force when the hydraulic actuator exceeds a predetermined value. And a hydraulic power steering device.

  In this case, when the steering force of the steering wheel is less than the predetermined value, the electric power steering device mainly transmits the steering assist force to the steering amount transmission means, and the steering force of the steering wheel is equal to or greater than the predetermined value. Both the electric power steering device and the hydraulic power steering device may transmit the steering assist force to the steering amount transmission means.

  The steering device according to the invention uses both the electric power steering device and the hydraulic power steering device, and uses both power steering devices properly depending on the magnitude of the steering force (for example, steering torque). That is, in a region where the steering force is small (below the predetermined value), the hydraulic actuator is configured not to generate (effective) driving force, so that the steering assist force cannot be obtained from the hydraulic power steering device. A steering assist force is generated mainly from the electric power steering device. In addition, in a region where the steering force is large (greater than or equal to a predetermined value), a driving force is also generated from the hydraulic actuator and the hydraulic power steering device generates a steering assist force. Therefore, from both the electric power steering device and the hydraulic power steering device Steering assist force is generated. In this way, the present invention switches between steering assistance by the electric power steering device and steering assistance by both the electric power steering device and the hydraulic power steering device in accordance with the steering force.

  The case where the steering force is small is, for example, when the vehicle is traveling. In such a case, the steering feeling against the delicate handling of the steering wheel affects the comfort during driving. For example, when the vehicle speed is high, the steering assist force is reduced to emphasize driving stability, while when the vehicle speed is low, the steering assist force is increased to emphasize handling performance. By performing integrated control, comfort during driving is obtained. Such fine control is unsuitable for hydraulic power steering devices that generate hydraulic drive force mechanically using hydraulic pressure, and the rotational drive force of the electric motor is freely controlled by the control means. It is suitable for an electric power steering device capable of performing fine integrated control. Focusing on this point, in the present invention, when the steering force is small (when the steering force is a predetermined value or less), the hydraulic power steering device does not work effectively, and the electric power steering device mainly having a high degree of freedom in setting the steering assist force. Generates a steering assist force, so that the electric power steering device can provide fine steering assistance. In addition, fuel efficiency can be improved by assisting steering by the electric power steering.

  On the other hand, when the steering force is large, for example, at the time of stationary, etc., in such a case, a large steering assist force is required. When the steering assist force is large, the electric motor of the electric power steering device may be in a high output state, and control such as overheat protection may work. When such protection control works, the output is limited, and thus the steering assist force may be insufficient. In this regard, in the present invention, when the steering force is large, that is, when a larger steering assist force is required, the steering assist force is output from the electric power steering device, and the hydraulic oil is supplied from the hydraulic pump of the hydraulic power steering device. Is effectively supplied to the hydraulic actuator, and an effective steering assist force is also generated from the hydraulic power steering apparatus. For this reason, even if the output of the electric motor of the electric power steering device is limited due to protection control, the steering assist force is provided from the hydraulic power steering device to compensate for that, so a large steering assist force is provided. Can be generated, and the occurrence of insufficient steering force can be prevented or effectively suppressed.

  Thus, the steering device of the present invention uses both power steering devices together so that the advantages of each of the electric power steering device and hydraulic power steering device can be fully utilized and the disadvantages of each power steering device can be compensated. The steering device can be obtained.

  In the above-described invention, the “predetermined value” of the steering force that is a threshold value at which hydraulic oil from the hydraulic pump is substantially supplied to the hydraulic actuator and the hydraulic actuator generates an effective driving force is not uniquely determined. The determination may be made in consideration of the necessity of fine steering control and the necessity of outputting a large steering assist force. Moreover, this predetermined value may not be fixed, for example, may change according to the vehicle speed.

  In the above invention, when the steering force is less than a predetermined value, the hydraulic actuator does not generate a driving force, but this means that an effective driving force is not generated, and even if a slight driving force is actually generated. In addition, the case where the driving force is weak and it cannot be said that steering assist is provided. For example, when the steering assist force based on the drive force from the hydraulic actuator is less than 10% of the steering assist force from the electric power steering device, no drive force is generated in the present invention. It is good. In order to actively reduce the driving force generated by the hydraulic power steering device when the steering force is less than a predetermined value, the characteristic of the driving force with respect to the steering force, for example, by chamfering the valve shape of the control valve mechanism. This can be realized by changing. In addition, by adjusting the dead zone area for the steering force by devising the valve shape of the control valve mechanism (for example, by increasing the width of the land or groove constituting the valve), the hydraulic power is reduced below the predetermined steering force. It is also possible to prevent driving force from being output from the steering device. In the above invention, “when the steering force is less than the predetermined value, the electric power steering device mainly transmits the steering assist force to the steering amount transmission means” means that when the steering force is less than the predetermined value, This means that it is sufficient if the power steering device is mainly used to transmit the steering assist force to the steering amount transmission means. At this time, a small amount of steering assist force is transmitted from the hydraulic power steering device to the steering amount transmission means. May be. For example, when the steering assist force from the electric power steering device is 90% or more of the total steering assist force, it may be considered that the electric power steering device mainly transmits the steering assist force to the steering amount transmission means. .

  The electric power steering device is attached to the steering amount transmitting means so as to be twisted by a steering operation of a steering handle, and has a first torsion bar having a predetermined lateral elastic coefficient, and a twist of the first torsion bar. Detecting means for detecting a steering force acting on the steering wheel based on the amount, and the control means controls the rotational driving force generated by the electric motor based on the steering force detected by the detecting means; There should be. Further, the hydraulic power steering device includes a second torsion bar attached to the steering amount transmission means so as to be twisted by a steering operation of a steering handle, and having a lateral elastic coefficient larger than the predetermined lateral elastic coefficient, The control valve mechanism controls the amount of oil flowing from the hydraulic pump to the hydraulic actuator so that the amount of hydraulic oil corresponding to the torsion amount of the second torsion bar is supplied from the hydraulic pump to the hydraulic actuator. It is good to do.

  According to this, the control valve mechanism of the hydraulic power steering device controls the amount of oil so that the amount of hydraulic oil corresponding to the amount of twist of the second torsion bar is supplied from the hydraulic pump to the hydraulic actuator. Further, the second torsion bar has a larger elastic modulus than that of the first torsion bar for detecting the steering force and is difficult to twist. When the steering force is small, the second torsion bar is hardly twisted (the twist amount is small). ). For this reason, the amount of oil supplied from the hydraulic pump to the hydraulic actuator according to the torsion amount is also reduced in comparison with the torsion bar having a small transverse elastic coefficient. Since the hydraulic actuator generates a driving force by the supplied hydraulic oil, the generated driving force is small when the supplied hydraulic oil is small. Therefore, when the steering force is small, the steering assist force generated from the hydraulic power steering device is extremely small, or the steering assist force is not generated from the hydraulic power steering device. On the other hand, when the steering force is large, the second torsion bar is also sufficiently twisted, so that the steering assist force generated by the hydraulic power steering device becomes large. With such a configuration, when the steering force is small (below a predetermined value), the electric power steering device generates mainly effective steering auxiliary force without effectively generating the steering auxiliary force from the hydraulic power steering device. When the force is large (when it is greater than or equal to a predetermined value), a steering device that generates a steering assist force from both the electric power steering device and the hydraulic power steering device can be realized.

From the above invention, the following technical idea can also be grasped.
In a vehicle steering apparatus having a steering amount transmission means for transmitting a steering operation amount of a steering wheel to a steered wheel, an electric motor that generates a rotational driving force and transmits the generated rotational driving force as a steering assist force to the steering amount transmission means. A motor and a first torsion bar attached to the steering amount transmitting means so as to be twisted by a steering operation of the steering handle and having a predetermined lateral elastic coefficient, and steering based on the torsion amount of the first torsion bar An electric power steering apparatus comprising: a detecting unit that detects a steering force acting on a steering wheel; and a control unit that controls a rotational driving force generated by the electric motor based on the steering force detected by the detecting unit; A hydraulic pump that discharges hydraulic oil and a driving force that is generated by supplying and discharging hydraulic oil discharged from the hydraulic pump. A hydraulic actuator that transmits the steering amount to the steering amount transmission unit as a steering assist force and a steering actuator that is attached to the steering amount transmission unit so as to be twisted by a steering operation of the steering handle and has a lateral elastic coefficient that is greater than the predetermined lateral elastic coefficient. 2 is provided in a main pipe that communicates the torsion bar 2 with the hydraulic pump and the hydraulic actuator, and an oil amount corresponding to the torsion amount of the second torsion bar is supplied from the hydraulic pump to the hydraulic actuator. And a hydraulic power steering device comprising a control valve mechanism for controlling the amount of oil flowing from the hydraulic pump to the hydraulic actuator.

  By the way, in the present invention described above, when the steering force is small (less than a predetermined value), the electric power steering apparatus capable of finely controlling the steering assist force generates the steering assist force, and the steering force When is large (when it is greater than or equal to a predetermined value), both the electric power steering device and the hydraulic power steering device generate steering assist force. In this case, when the electric power steering device is operating normally, steering assistance is performed by the electric power steering device until the steering force reaches the predetermined value, so that the driver can steer the steering wheel without difficulty. . However, when the electric power steering device does not operate normally and no steering assist force is generated from the electric power steering device, the steering assist force is not applied until the steering torque reaches the predetermined value. In this case, the driver needs to steer the steering wheel without steering assistance. For example, the hydraulic power steering device does not generate an effective steering assistance force until a predetermined steering force is input. Because the steering assist force is generated by using a torsion bar that is large and difficult to twist, a large steering force is required to twist the torsion bar that is difficult to twist in this way, and the driver needs a large amount to obtain the steering assist force. The steering wheel must be operated with the steering force.

  In order to prevent such a problem, in the present invention, the steering device generates a reaction force that opposes the steering force, and transmits the generated reaction force to the steering amount transmission unit. The reaction force generated by the reaction force generation unit is controlled so that the reaction force transmitted to the steering amount transmission unit decreases when either the power steering device or the hydraulic power steering device is not operating normally. Reaction force control means. The reaction force generation means is a hydraulic reaction force mechanism that generates a reaction force by the pressure of hydraulic oil discharged from the hydraulic pump, and the reaction force control means is that the electric power steering device is not operating normally. In this case, it is preferable that the pressure release means release pressure as a reaction force obtained by the hydraulic reaction force mechanism. In this case, the hydraulic power steering apparatus includes a deformable member such as a torsion bar that can be deformed by a steering operation of the steering handle, and the control valve mechanism supplies an oil amount corresponding to the deformation amount of the deformable member from the hydraulic pump to the hydraulic pressure. The amount of oil flowing from the hydraulic pump to the hydraulic actuator may be controlled so as to be supplied to the actuator.

  According to the above invention, for example, when the hydraulic power steering device is provided with a hydraulic reaction force mechanism as a reaction force generating means, and the hydraulic power steering device is a method of generating a driving force according to the torsion amount of the torsion bar. Since the reaction force opposes the steering force input from the steering handle, the steering force twists the torsion bar against the reaction force. In other words, even if the torsion bar itself is easy to twist with a small lateral elastic modulus, the apparent lateral elastic modulus of the torsion bar increases by the reaction force, so the torsion bar twists by the increase of the reaction force. It becomes difficult. For this reason, the twisting amount of the torsion bar with respect to the steering force decreases according to the magnitude of the reaction force, and the steering assist force is not effectively generated from the hydraulic power steering device in a region where the steering force is small. Therefore, in this case, if the electric power steering apparatus is operating normally, the steering assist force is generated mainly by the electric power steering apparatus in a region where the steering torque is small.

  On the other hand, when the electric power steering device fails and cannot operate normally, the pressure release means operates to release the pressure that is the basis of the reaction force obtained by the hydraulic reaction force mechanism. Thus, the reaction force acting on the steering amount transmission means from the hydraulic reaction force mechanism is reduced. As a result, the apparent lateral elastic modulus of the torsion bar used in the hydraulic power steering apparatus is reduced, and the torsion bar can be sufficiently twisted with a small steering force. Therefore, in this case, the steering assist force can be generated from the hydraulic power steering apparatus without imposing a burden on the driver with a small steering force.

  As described above, in the present invention, when both the steering devices are normal, the reaction force is applied to the steering amount transmission means, and when one of the steering devices is not operating normally, the reaction amount is applied to the steering amount transmission means. By reducing or eliminating the reaction force to be applied, the burden on the driver when one of the steering devices is not operating normally can be reduced. The reaction force generation means is provided on the electric power steering device side, and when both power steering devices are operating normally, the reaction force generated by the reaction force generation means is applied to the steering amount transmission means, thereby providing hydraulic power steering. If the device does not operate normally, the reaction force acting on the steering amount transmission means may be reduced or eliminated. According to this, since the reaction force transmitted to the steering amount transmission means is reduced or the reaction force is not transmitted when the hydraulic power steering device is not operating normally, the steering assist force from the electric power steering device is reduced. This increases the amount of steering operation burden on the driver.

From the above invention, the following technical idea can be grasped.
In a vehicle steering apparatus having a steering amount transmission means for transmitting a steering operation amount of a steering wheel to a steered wheel, an electric motor that generates a rotational driving force and transmits the generated rotational driving force as a steering assist force to the steering amount transmission means. An electric power steering device comprising a motor and a control means for controlling a rotational driving force generated by the electric motor based on a steering force acting on a steering handle; a hydraulic pump for discharging hydraulic oil; and the hydraulic pump A hydraulic actuator that generates a driving force by supplying and discharging discharged hydraulic oil, and transmits the generated driving force as a steering assisting force to the steering amount transmitting means, and a main that communicates the hydraulic pump and the hydraulic actuator. Provided from the hydraulic pump to the hydraulic actuator based on a steering force provided in the pipe and acting on the steering handle. A hydraulic power steering device having a control valve mechanism for adjusting the amount of oil; a reaction force generating means for generating a reaction force against the steering force; and transmitting the generated reaction force to the steering amount transmitting means; and the electric power steering The reaction force for controlling the reaction force generated by the reaction force generation means so that the reaction force transmitted to the steering amount transmission means is reduced when either the device or the hydraulic power steering device is not operating normally. And a steering means.

  Further, at least one of the electric power steering device and the hydraulic power steering device increases a steering assist force when either the electric power steering device or the hydraulic power steering device is not operating normally. Auxiliary force increasing means may be provided. According to this, when either the electric power steering device or the hydraulic power steering device does not operate normally, the assisting force generated from the normally operating power steering device is increased by the auxiliary force increasing means. Will be increased. The increase in the steering assist force compensates for the steering assist force that should have been generated from the power steering device on the side that is not operating normally, thereby reducing the burden of the steering operation on the driver.

  The auxiliary power increasing means is provided in the hydraulic power steering device, and suppresses an amount of oil supplied from the hydraulic pump to the hydraulic actuator when the electric power steering device is operating normally. It is preferable that the amount of oil supplied from the hydraulic pump to the hydraulic actuator is increased when the apparatus does not operate normally. In this case, the auxiliary force increasing means is provided in a bypass pipe that branches from the main pipe and returns to the hydraulic pump without passing through the control valve mechanism and the hydraulic actuator, so that the electric power steering device operates normally. It is possible to provide a boosting means for boosting when not operating. This boosting means is preferably controlled so as not to boost when the electric power steering apparatus is operating normally.

  According to this, when the electric power steering apparatus is operating normally, the boosting means does not boost the pressure, so that the hydraulic oil discharged from the hydraulic pump flows through both the main pipe and the bypass pipe. For this reason, the amount of oil flowing through the main pipe is relatively reduced, and the driving force output from the hydraulic power steering apparatus is reduced. Therefore, when the steering torque is small, an effective steering assist force is not generated from the hydraulic power steering apparatus, and the steering assist force is generated mainly by the electric power steering apparatus. On the other hand, when the electric power steering apparatus is not operating normally, the boosting means boosts the pressure, so that the hydraulic oil hardly flows through the bypass pipe. For this reason, the amount of oil flowing through the main pipe is relatively increased, and the driving force output from the hydraulic power steering apparatus is increased. Therefore, in this case, an effective steering assist force is generated from the hydraulic power steering apparatus even if the steering torque is small. For this reason, when the electric power steering apparatus is not operating normally, the steering assist force can be generated from the hydraulic power steering apparatus without imposing a burden on the driver with a small steering force.

  Further, the auxiliary force increasing means reduces the opening degree of the throttle valve means when the throttle valve means inserted in the main pipe and the electric power steering device are operating normally, and The power steering apparatus may include opening degree adjusting means for adjusting the opening degree of the throttle valve means so as to increase the opening degree of the throttle valve means when the power steering device is not operating normally. Further, the auxiliary force increasing means reduces the output rotational speed of the pump driving electric motor for driving the hydraulic pump and the pump driving electric motor when the electric power steering device is operating normally. And a rotation speed adjusting means for adjusting the rotation speed of the pump driving electric motor so as to increase the output rotation speed of the pump driving electric motor when the electric power steering device is not operating normally. It can be provided. Even with this configuration, the same effects as described above can be obtained.

From the above invention, the following technical idea can be grasped.
In a vehicle steering apparatus having a steering amount transmission means for transmitting a steering operation amount of a steering wheel to a steered wheel, an electric motor that generates a rotational driving force and transmits the generated rotational driving force as a steering assist force to the steering amount transmission means. An electric power steering device comprising a motor and a control means for controlling a rotational driving force generated by the electric motor based on a steering force acting on a steering handle; a hydraulic pump for discharging hydraulic oil; and the hydraulic pump A hydraulic actuator that generates a driving force by supplying and discharging discharged hydraulic oil, and transmits the generated driving force as a steering assisting force to the steering amount transmitting means, and a main that communicates the hydraulic pump and the hydraulic actuator. Provided from the hydraulic pump to the hydraulic actuator based on a steering force provided in the pipe and acting on the steering handle. Provided in at least one of a hydraulic power steering device having a control valve mechanism for adjusting the amount of oil and the electric power steering device or the hydraulic power steering device, and either the electric power steering device or the hydraulic power steering device A steering device comprising: an auxiliary force increasing means for increasing the steering auxiliary force when the other is not operating normally.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of a steering apparatus 1 according to the first embodiment of the present invention.

  As shown in FIG. 1, the steering device 1 of the present embodiment includes a steering shaft 20 and a steering shaft 30. The steering shaft 20 is further provided with a first steering shaft 210 and a second steering shaft 220. The first steering shaft 210 and the second steering shaft 220 are mechanically connected by an intermediate shaft (not shown). A steering handle 11 is coaxially connected to one end of the first steering shaft 210. By the steering operation (turning operation) of the steering handle 11, the first steering shaft 210 rotates around the axis. This rotation is also transmitted to the second steering shaft 220 via the intermediate shaft described above, and the second steering shaft 220 is also rotated by this transmission.

  The first steering shaft 210 has a first shaft 211 and a second shaft 212, and the first shaft 211 is connected to the steering handle 11. A first torsion bar 41 is provided between the first shaft 211 and the second shaft 212. The first torsion bar 41 has one end fixed to the first shaft 211 and the other end fixed to the second shaft 212, and the first shaft 211 rotates with the steering operation (rotation operation) of the steering handle 11. Then it is twisted.

  An electric power steering device 40 is attached to the first steering shaft 210. The electric power steering device 40 includes a first torsion bar 41 described above, a pair of detection means 42a and 42b attached to both ends of the first torsion bar 41, a control unit (ECU) 43, an electric motor 44, and the like. The speed reducer 45 is provided. The detection means 42a and 42b detect the twist amount of the first torsion bar 41 and calculate and output the steering torque (steering force) input to the steering handle 11 from the detected twist amount. The steering torque output by the detection means 42 a and 42 b is input to the control device 43. Then, the control device 43 calculates an assist torque (steering assist force) corresponding to the input steering torque, and controls the electric motor 44 through a motor drive circuit (not shown) so that the calculated assist torque is transmitted to the steering shaft 20. Outputs a command. The electric motor 44 is connected to the second shaft 212 via the speed reducer 45, and rotates at a rotational speed according to a control command from the control means to generate a rotational driving force. The rotation of the electric motor 44 is transmitted to a speed reducer 45 such as a worm speed reducer, for example. The speed reducer 45 reduces the rotational speed and increases the rotational torque. Then, a desired rotational torque is transmitted from the reduction gear 45 to the steering shaft 20 (second shaft 212) as an assist torque.

  The control device 43 includes a microcomputer including a CPU, ROM, RAM, and the like as main components. As described above, the steering torque is input from the detecting means 42a and 42b, the vehicle speed is detected from the vehicle speed sensor, and the steering handle is detected from the steering angle sensor. 11 steering angles may be input. The control device 43 executes a predetermined assist control program based on these input information, calculates the assist torque based on the steering torque and other information, and inputs the calculated assist torque to the steering shaft 20. The rotational torque generated by the electric motor 44 is controlled by current or the like. This assist torque is generally set so that it increases as the steering torque increases and decreases as the vehicle speed increases. However, the optimum assist torque may be set individually depending on various vehicle conditions. it can. As described above, the electric power steering device 40 can set the assist torque finely according to the situation.

  The second steering shaft 220 has an input shaft 221 and an output shaft (or pinion shaft) 222. The input shaft 221 and the output shaft 222 are connected by the second torsion bar 51. The second torsion bar 51 has one end connected to the input shaft 221 and the other end connected to the output shaft 222. When rotational torque is applied from the input shaft 221 side, the second torsion bar 51 is twisted by an amount corresponding to the torque. It is configured. A pinion gear 222 a is formed on one end side of the output shaft 222.

  The steering shaft 30 includes a shaft portion 31. The steered wheels FW1 and FW2 are connected to both ends of the shaft portion 31 via knuckle arms (not shown). A rack portion 32 is formed on the shaft portion 31. The rack portion 32 is meshed with the above-described pinion gear 222a, and the pinion gear 222a and the rack portion 32 constitute a rack and pinion mechanism. The rack and pinion mechanism converts the rotation of the steering shaft 20 into the axial movement of the steering shaft 30. The steered wheels FW1 and FW2 are steered by the converted axial movement. The steering shaft 20 and the steering shaft 30 constitute a steering amount transmission means for transmitting the steering operation amount (rotation operation amount) of the steering handle 11 to the steered wheels FW1 and FW2.

  A hydraulic power steering device 50 is attached to the second steering shaft 220 and the steering shaft 30. The hydraulic power steering apparatus 50 includes a second torsion bar 51, a control valve mechanism 52, a hydraulic pump 53, a power cylinder 54, a main pipe 55a communicating the hydraulic pump 53 and the power cylinder 54, a reservoir And a tank 56. The second torsion bar 51 connects the input shaft 221 and the output shaft 222 as described above, and when the rotational torque is applied from the input shaft 221, the second torsion bar 51 is twisted by the rotational torque. This twist causes an angular displacement in the rotational direction between the input shaft 221 and a valve sleeve 521 described later.

  The control valve mechanism 52 is provided in a main pipe 55a between the hydraulic pump 53 and the power cylinder 54, and includes a cylindrical valve sleeve 521 into which the input shaft 221 and the second torsion bar 51 are inserted. ing. The valve sleeve 521 is connected to the output shaft 222 and rotates coaxially and integrally with the output shaft 222. The valve sleeve 521 has four ports (first port 521a, second port 521b, third port 521c, and fourth port 521d) formed on the outer wall thereof. Four oil passages that connect these ports are formed between the inside of the valve sleeve 521 and the input shaft 221. The first oil passage P12 communicates the first port 521a and the second port 521b. The second oil passage P13 communicates the first port 521a and the third port 521c. The third oil passage P24 communicates the second port 521b and the fourth port 521d. The fourth oil passage P34 connects the third port 521c and the fourth port 521d. The first port 521a communicates with the discharge port 53b of the hydraulic pump 53 through the main pipe 55a. The fourth port 521d communicates with the reservoir tank 56 through the drain pipe 55b.

  Although not shown, the opposing surface between the valve sleeve 521 and the input shaft 221 (or the valve rotor attached to the outer periphery of the input shaft 221) is formed in an uneven shape, and the space between the uneven opposing surfaces is As the input shaft 221 rotates relative to the valve sleeve 521, the arrangement state of the concave and convex opposing surfaces changes, and this change changes the channel cross-sectional area of each oil passage. Then each oil passage is squeezed. In other words, when the input shaft 221 rotates inside the valve sleeve 521 by transmitting rotational torque from the first steering shaft 20 side, the second torsion bar 51 is twisted by this rotation, and the second torsion bar 51 is twisted. An angular displacement occurs between the valve sleeve 521 and the input shaft 221 by the amount. The inner wall shape of the valve sleeve 521 is formed so that the cross-sectional area of each oil passage changes in accordance with the amount of angular displacement. The amount of oil flowing through each oil passage is adjusted by the change in the cross-sectional area of the flow passage. Therefore, flow control valves A, A ′, B, and B ′ formed by the valve sleeve 521 and the input shaft 221 are inserted in the oil passages P12, P13, P24, and P34, respectively. (See FIG. 2).

The hydraulic pump 53 has a suction port 53a and a discharge port 53b. The hydraulic pump 53 is driven by a driving force from a driving source such as an engine or a motor and sucks hydraulic oil in the reservoir tank 56 from the suction port 53a through a suction pipe 55c. The discharged hydraulic oil is discharged from the discharge port 53b into the main pipe 55a. In this embodiment, the hydraulic pump 53 is driven by an engine.

  The power cylinder 54 operates as a hydraulic actuator according to the present invention, and supplies and discharges (supply / discharge) the hydraulic oil discharged from the hydraulic pump 53, thereby generating a driving force and steering the generated driving force. It is transmitted to the shaft 30. The power cylinder 54 has a space filled with hydraulic oil therein. The shaft portion 31 is inserted into the internal space, and the internal space is partitioned into a left chamber 54L and a right chamber 54R by a power piston 541 attached to the shaft portion 31. The power cylinder 54 is formed with a left port 54a that communicates with the left chamber 54L and a right port 54b that communicates with the right chamber 54R. The left port 54a communicates with the second port 521b of the valve sleeve 521 through the main pipe 55a, and the right port 54b communicates with the third port 521c of the valve sleeve 521 through the main pipe 55a.

  FIG. 2 is a hydraulic circuit diagram of the hydraulic power steering apparatus 50. As shown in FIG. 2, a control valve mechanism 52 is interposed between the hydraulic pump 53 and the power cylinder 54. The control valve mechanism 52 is configured as a four-way throttle valve as shown in FIG. 2, and each valve is controlled in accordance with the relative angular displacement between the input shaft 221 and the valve sleeve 521 accompanying the steering operation of the steering handle 11. The aperture amount is variable. Specifically, when the second torsion bar 51 is twisted by the steering operation of the steering handle 11 and the rotational position of the input shaft 221 and the valve sleeve 521 is shifted in one direction, the first port 521a and the second port 521b are connected. The valve A in the first oil passage P12 that communicates, and the valve A ′ in the fourth oil passage P34 that communicates the third port 521c and the fourth port 521d open, and the first port 521a and the third port 521c The valve B in the second oil passage P13 that communicates with the valve B and the valve B ′ in the third oil passage P24 that communicates with the second port 521b and the fourth port 521d are closed. For this reason, the hydraulic oil that has reached the first port 521a from the hydraulic pump 51 mainly flows through the first oil passage P12 side where the valve is open, and reaches the second port 521b. From the second port 521b, the left port 54a And then flows to the left chamber 54L of the power cylinder 54. As a result, hydraulic oil from the hydraulic pump 53 is supplied to the left chamber 54L, and hydraulic pressure is generated by the supplied hydraulic oil, and the power piston 541 receives pressure from the left surface in the drawing. By transmitting this pressure to the shaft portion 31, the shaft portion 31 generates an axial driving force, and this axial driving force is used as an assist force.

  When the steering handle 11 is steered by receiving the assist force and the shaft portion 31 and the power piston 541 attached to the shaft portion 31 move rightward in the drawing, the volume of the right chamber 54R in the power cylinder 54 decreases. Accordingly, the hydraulic oil in the right chamber 54R is discharged from the right port 54b. The discharged hydraulic oil enters the third port 521c through the main pipe 55a, reaches the fourth port 521d from the third port 521c through the fourth oil passage P34 where the valve is open, and from the fourth port 521d. It reaches the reservoir tank 56 through the drain pipe 55b.

  On the other hand, when the second torsion bar 51 is twisted by the steering operation of the steering handle 11 and the rotational direction positions of the input shaft 221 and the valve sleeve 521 are shifted in the other direction, the valve B and the valve B ′ are opened contrary to the above, Valve A and valve A ′ are closed. Accordingly, the hydraulic oil flowing in from the first port 521a flows to the third port 521c through the second oil passage P13 where the valve is open, and passes through the right port 54b from the third port 521c to the right chamber 54R of the power cylinder 54. Flowing into. As a result, the hydraulic oil from the hydraulic pump 53 is supplied to the right chamber 54R, and the power piston 541 receives pressure from the right side of the figure by the supplied hydraulic oil. By transmitting this pressure to the shaft portion 31, the shaft portion 31 generates an axial driving force, and this axial driving force is used as an assist force.

  When the steering handle 11 is steered by receiving the assist force described above, and the shaft portion 31 and the power piston 541 attached to the shaft portion 31 move to the left in the drawing, the left chamber 54L in the power cylinder 54 is moved. Accordingly, the hydraulic oil in the left chamber 54L is discharged from the left port 54a. The discharged hydraulic oil enters the second port 521b through the main pipe 55a, reaches the fourth port 521d from the second port 521b through the third oil passage P24 where the valve is open, and from the fourth port 521d. It reaches the reservoir tank 56 through the drain pipe 55b.

  Further, when the second torsion bar 51 is not twisted such as when the steering handle 11 is in a neutral state, all the valves A, A ', B, B' are opened. Therefore, in this case, the hydraulic oil that has flowed from the hydraulic pump 51 to the first port 521a flows to both the flow path P12 and the flow path P13. The hydraulic oil that has reached the second port 521b from the flow path P12 flows through the flow path P24 and reaches the fourth port 521d. The hydraulic oil that has reached the third port 521c from the flow path P13 flows through the flow path P34 and reaches the fourth port 521d. Then, they merge at the fourth port 521d and flow to the reservoir tank 56 through the drain pipe 55b. As described above, when the second torsion bar 51 is not twisted, the oil from the hydraulic pump 53 reaches the reservoir tank 56 without flowing through the power cylinder 54.

  In the steering device 1 of the present embodiment, the lateral elastic modulus k2 of the second torsion bar 51 is set larger than the lateral elastic modulus k1 of the first torsion bar 41. That is, the second torsion bar 51 is harder to twist than the first torsion bar 41. Therefore, when the steering torque input to the steering handle 11 by the driver is small, only the first torsion bar 41 is twisted and the second torsion bar 51 is not substantially twisted (actually, it is slightly twisted, With this minute twist, the hydraulic power steering device 50 does not generate an effective driving force). Therefore, when the steering torque is small, substantially only the electric power steering device 40 works, and the electric motor 44 is driven according to the magnitude of the steering torque detected by the torsion of the first torsion bar 41, and the electric power Steering assistance by the steering device 40 is performed. For example, in a steering operation while traveling, the steering torque is small, and in such a case, only the electric power steering device 40 substantially works to perform steering assist. The electric power steering device 40 can set the assist torque in detail according to various situations by performing integrated control of the assist torque according to various input information as described above. Therefore, when the steering torque is small (below a predetermined value), the driver can perform a comfortable steering operation without losing the steering feeling by fine steering assistance from the electric power steering device 40.

  On the other hand, when the steering torque input by the driver is large, not only the first torsion bar 41 but also the second torsion bar 51 is sufficiently twisted according to the magnitude of the steering torque. Therefore, an assist torque is generated from the electric power steering device 40 according to the twist of the first torsion bar 41, and an assist force is also generated from the hydraulic power steering device 50 according to the twist of the second torsion bar 51. Thus, steering assist is performed by both the electric power steering device 40 and the hydraulic power steering device 50. Here, for example, when performing a stationary operation or when the front mass of the vehicle is large, a very large steering torque is required. At this time, the assist torque is supplied to the steering shaft 20 only from the electric power steering device 40. In such a case, the electric motor 44 may be in a high output state (high voltage / high current state), and control such as overheat protection may be activated to limit the output torque. In such a case, the assist torque is also limited in accordance with the output limitation, which places a burden on the driver for the steering operation. On the other hand, in this embodiment, when the steering torque is large, the steering assist force is generated not only from the electric power steering device 40 but also from the hydraulic power steering device 50. Therefore, from the electric power steering device 40 as described above, Even if the assist torque is limited, it can be supplemented by the assist force from the hydraulic power steering device 50. Therefore, sufficient steering assist can be performed even when the steering torque is large, and the driver's steering operation is not burdened.

  FIG. 3 is a graph showing changes in steering assist force (assist torque, assist force) with respect to the steering torque for each power steering device. In the figure, a solid line is a graph showing a change in assist torque with respect to the steering torque in the electric power steering device 40, and a one-dot chain line is a graph showing a change in assist force with respect to the steering torque in the hydraulic power steering device 50. As can be seen from this graph, according to the steering device 1 of the present embodiment, the hydraulic power steering device 50 does not work effectively in a region where the steering torque is small (the steering torque is less than the predetermined value T), and the electric power steering device is mainly used. The assist torque from 40 is transmitted to the steering amount transmitting means, and in the region where the steering torque is large (the steering torque is equal to or greater than a predetermined value T), the assist torque from the electric power steering device 40 and the assist force from the hydraulic power steering device 50 are It is transmitted to the steering amount transmission means. For this reason, when the steering torque is small, fine integrated control can be performed by the electric power steering device 40. On the other hand, when a large steering torque such as stationary is required, both the electric power steering device 40 and the hydraulic power steering device 50 can be used. A large steering assist force can be obtained.

  Further, in order to achieve the above-described effects, the lateral elastic modulus k2 of the second torsion bar 51 provided in the hydraulic power steering apparatus 50 is greater than the lateral elastic modulus k1 of the first torsion bar 41 for detecting the steering torque. Has also been enlarged. That is, the second torsion bar 51 is difficult to twist and is formed so that the amount of twist with respect to the input torque is small. Therefore, the driving force is not effectively generated from the hydraulic power steering device 50 in a region where the steering torque is small. Therefore, although the electric power steering device 40 and the hydraulic power steering device 50 are used together, steering assist is performed mainly by the electric power steering device 40 when the steering torque is small, and both when the steering torque is large. Steering assistance is performed by the power steering device. Thereby, both can be used together, utilizing the merit of each power steering device.

  In the present embodiment, the first torsion bar 41 is used to detect the steering torque. However, if the steering torque can be detected by another method, the first torsion bar 41 can be omitted. In this case, the second torsion bar 51 used in the hydraulic power steering apparatus 50 may be a torsion bar having a larger transverse elastic coefficient than the torsion bar used in the normal hydraulic power steering apparatus. In this way, the amount of twist with respect to the steering torque is smaller than that of a normal hydraulic power steering device, and when the steering torque is small, effective assist force is not generated from the hydraulic power steering device, and the electric power steering device 40 is mainly used. Steering assist can be performed with the assist torque from.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The basic configuration of the present embodiment is the same as that of the first embodiment. Therefore, since the outline of the steering apparatus of this embodiment is the same as that of the steering apparatus 1 shown in FIG. 1, this figure shall be used. FIG. 4 is a hydraulic circuit diagram applied to the steering apparatus according to the second embodiment of the present invention. As shown in the figure, in the steering device of the present embodiment, a hydraulic reaction force mechanism 58 is provided in the hydraulic power steering device 50, and the hydraulic reaction force from the hydraulic reaction force mechanism 58 is applied to the steering amount transmission means. Is different from the first embodiment. Hereinafter, different points will be mainly described, and the same components as those in the first embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

  As shown in FIG. 4, a distributor (flow divider) 57, a hydraulic reaction force mechanism 58, and a reaction force electromagnetic flow rate adjustment valve 59 are provided in the hydraulic circuit of the hydraulic power steering apparatus 50 in the present embodiment. Yes. The distributor 57 is provided between the hydraulic pump 53 and the first port 521a in the main pipe 55a. The distributor 57 includes a main oil passage 57a and a branch oil passage 57b. The main oil passage 57a communicates the hydraulic pump 53 and the first port 521a. The branch oil passage 57b branches off from the main oil passage 57a and communicates the hydraulic pump 53 and the reservoir tank 56. Further, a throttle 57c is provided in the main oil passage 57a, and a throttle 57d is provided in the branch oil passage 57b. The amount of oil flowing through the main oil passage 57a and the branch oil passage 57b is adjusted according to the ratio of these throttles.

  The hydraulic reaction force mechanism 58 communicates with the branch oil passage 57b and forms a hydraulic reaction force chamber 58a therein. An input shaft 221 is inserted through the hydraulic reaction force chamber 58a. As shown in FIG. 4, the input shaft 221 inserted into the hydraulic reaction force chamber 58a is formed with two flat wings 221a symmetrically outward in the radial direction, and these wings 221a are hydraulically reactive. Arranged in the force chamber 58a. Further, two pairs (four) of plungers 581 and 582 are diagonally arranged around the input shaft 221 so as to face both surfaces of the wing portion 221a. The surface (rear surface) opposite to the surface facing the wing portion 221 a of each plunger 581, 582 receives hydraulic pressure generated by the hydraulic oil discharged from the hydraulic pump 53. In order for the input shaft 221 to rotate in this state, the wing portion 221a abuts against the plungers 581 and 582, and the input shaft 221 causes the plungers 581 and 582 to move by rotational torque against the hydraulic pressure received by the plungers 581 and 582. Need to push away. At this time, the resistance force acting from the plungers 581 and 582 acts as a reaction force against the steering torque applied to the input shaft 221.

  The reaction force electromagnetic flow rate adjusting valve 59 corresponds to the pressure release means of the present invention, and the opening degree is adjusted by a control command from a control device (not shown). When the reaction force electromagnetic flow rate adjusting valve 59 is closed, a hydraulic reaction force is generated by the hydraulic pressure acting on the hydraulic reaction force chamber 58 a from the hydraulic pump 53, and this hydraulic reaction force acts on the input shaft 221. To do. On the other hand, when the reaction force electromagnetic flow rate adjustment valve 59 is open, hydraulic oil for supplying hydraulic pressure to the plungers 581 and 582 flows into the reservoir tank 56, so that the hydraulic pressure acts on the back surfaces of the plungers 581 and 582. Accordingly, the reaction force from the hydraulic reaction force mechanism 58 does not act on the input shaft 221.

  The hydraulic reaction force generated in the hydraulic reaction force mechanism 58 is a force that opposes the steering torque, and acts as a force that makes the input shaft 221 difficult to rotate. Therefore, the steering torque input to the input shaft 221 from the steering handle 11 rotates the input shaft 221 against this hydraulic reaction force, and therefore the force for rotating the input shaft 221 is a component of the hydraulic reaction force. Only decrease. That is, the hydraulic reaction force acts as a force that increases the torsional resistance of the second torsion bar 51 attached between the input shaft 221 and the output shaft 222, and as a result, the apparent torsion of the second torsion bar 51. The resistance increases by the amount of hydraulic reaction force. As described above, in this embodiment, the apparent torsional resistance of the second torsion bar 51 is a value obtained by adding the hydraulic reaction force to the torsional resistance corresponding to the actual lateral elastic modulus of the second torsion bar 51. Even if it is small, it appears as a torsion bar having a large transverse elastic modulus. In the present embodiment, for example, the transverse elastic modulus of the second torsion bar 51 can be equal to or less than the transverse elastic modulus k1 of the first torsion bar 41.

  In the above configuration, when the electric power steering device 40 is operating normally, the reaction force electromagnetic flow rate adjusting valve 59 is closed. Therefore, the hydraulic reaction force acts on the input shaft 221 from the hydraulic reaction force mechanism 58. For this reason, the apparent lateral elastic modulus of the second torsion bar 51 is increased by the amount of the hydraulic reaction force, and it is difficult to twist. Therefore, the second torsion bar 51 can hardly be twisted with a small steering torque (below a predetermined torque), and therefore the assist force is hardly generated from the hydraulic power steering device 50. Therefore, in this case, assist torque is mainly generated from the electric power steering device 40, and steering assist is performed by the assist torque. As described above, since the electric power steering device 40 can set the assist torque amount as appropriate in accordance with various situations, fine integration control is performed by the electric power steering device 40 when the steering torque is small.

  When the steering torque input from the steering handle 11 increases, the steering torque acts on the second torsion bar 51 against the torsional resistance and hydraulic reaction force of the second torsion bar 51, and the second torsion bar 51 Is twisted. The second torsion bar 51 is twisted to cause an angular displacement between the input shaft 221 and the valve sleeve 521, and hydraulic oil discharged from the hydraulic pump is supplied to and discharged from the power cylinder 54 according to the magnitude of the angular displacement. An assist force is also generated from the power steering device 50. Therefore, when the steering torque is large (greater than or equal to the predetermined torque), steering assist is performed by both the assist torque from the electric power steering device 40 and the assist force from the hydraulic power steering device 50. Therefore, even if the output of the electric power steering device 40 is limited, it can be compensated by the assist force from the hydraulic power steering device 50.

  Here, when the electric power steering device 40 does not operate normally due to an operation failure of the electric motor 44 or a connection failure of the electric circuit, the electric motor 44 cannot be driven, and the assist torque cannot be generated. The case where it becomes is assumed. In this case, in the steering device 1 according to the first embodiment, the steering operation is performed by receiving the assist force only from the hydraulic power steering device 50, but the second torsion bar used in the hydraulic power steering device 50 is used. The elastic modulus k2 of 51 is large, and the second torsion bar 51 is difficult to twist. Therefore, the driver has to twist the second torsion bar 51 that is difficult to twist by operating the steering handle 11 with a large steering torque until the assist power is effectively generated from the hydraulic power steering device 50. .

  On the other hand, in the steering device according to the present embodiment, when the electric motor 44 cannot be driven and the assist torque cannot be generated, the control device 43 detects this, and the electric power A signal (for example, a warning signal) that the steering device 40 has failed is issued. At the same time, the reaction force electromagnetic flow rate adjusting valve 59 is opened. When the reaction force electromagnetic flow rate adjusting valve 59 is opened, the hydraulic oil acting on the plungers 581 and 582 in the hydraulic reaction force chamber 58a flows into the reservoir tank 56, so that the pressure in the hydraulic reaction force chamber 58a is released. Thus, the hydraulic reaction force does not act on the input shaft 221. As a result, the hydraulic reaction force as a resistance force against twisting the second torsion bar 51 is eliminated, and the second torsion bar 51 is twisted according to the actual transverse elastic coefficient. In the present embodiment, since the actual lateral elastic modulus of the second torsion bar 51 is equal to or less than the lateral elastic modulus of the first torsion bar 41, the second torsion bar 51 can be largely twisted by a slight steering torque. Thus, an effective assist force can be generated from the hydraulic power steering device 50 with a slight steering torque.

  As described above, according to the steering apparatus of the present embodiment, the hydraulic power steering apparatus 50 includes the hydraulic reaction force mechanism 58 as a reaction force generation unit, and the hydraulic reaction force mechanism 58 counters the steering force. Will occur. As a result, the torsional resistance of the second torsion bar 51 increases by the amount of the hydraulic reaction force, the apparent lateral elastic modulus of the second torsion bar increases, making it difficult for the second torsion bar 51 to twist, and the amount of twisting with respect to the steering force Decrease. Therefore, in the region where the steering force is small, the assisting force is not effectively applied from the hydraulic power steering device 50, and the steering assist can be performed mainly by the electric power steering device 40. Further, in a situation where the electric power steering device 40 cannot operate normally due to a failure or the like, the hydraulic force in the hydraulic reaction force chamber 58a is released by opening the reaction force electromagnetic flow rate adjustment valve 59, and the hydraulic reaction force mechanism The hydraulic reaction force acting from 58 is reduced (or made zero). As a result, the apparent lateral elastic modulus of the second torsion bar 51 is reduced (becomes the original lateral elastic modulus), and the second torsion bar 51 can be sufficiently twisted with a small steering force. Therefore, when the electric power steering apparatus 40 is not operating normally, an effective steering assist force can be generated from the hydraulic power steering apparatus 50 without imposing a burden on the driver with a small steering force.

(Modification 1)
FIG. 5 is a modification of the hydraulic circuit of the steering device of the present embodiment. In this modified example, the reaction force electromagnetic flow rate adjusting valve 59 is arranged on the upstream side of the hydraulic reaction force chamber 58a. Therefore, the reaction force electromagnetic flow rate adjustment valve 59 is opened to effectively apply the hydraulic reaction force of the hydraulic reaction force mechanism 58, and the reaction force electromagnetic flow rate adjustment valve 59 is closed to prevent it from acting. State. A relief branch passage 57e branches from the branch oil passage 57b from a portion downstream of the portion of the branch oil passage 57b to which the hydraulic reaction force chamber 58a is connected. A relief valve RB is interposed in the relief branch passage 57e. The relief valve RB is used when the hydraulic reaction force generated by the hydraulic reaction force mechanism 58 does not need to be applied to the input shaft 221 even when the electric power steering device 40 is operating normally. When the oil pressure to be applied at 58 becomes equal to or higher than a predetermined pressure, the pressure oil that is applied to the plungers 581 and 582 in the hydraulic reaction force chamber 58 a is caused to flow to the reservoir tank 56. As a result, the hydraulic reaction force can be applied to the input shaft 221 from the hydraulic reaction force mechanism 58 only when necessary. Since the generation of the hydraulic reaction force places a load on the hydraulic pump 53, it is not preferable to always generate the hydraulic reaction force from the viewpoint of energy saving such as fuel consumption. Therefore, it is possible to provide a steering device that contributes to energy saving by generating a hydraulic reaction force that is necessary only when necessary.

(Third embodiment)
Next, a third embodiment of the present invention will be described. The schematic configuration of the steering apparatus according to this embodiment is the same as that of the steering apparatus 1 shown in FIG. FIG. 6 is a hydraulic circuit diagram applied to the steering device according to the present embodiment. The steering device of the present embodiment is characterized in that a control valve mechanism for boosting is provided in the hydraulic circuit of the hydraulic power steering device 50. The following description will focus on the characteristic points, and the same components as those in the first embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

  As shown in FIG. 6, the hydraulic power steering apparatus according to the present embodiment includes a bypass pipe 55d branched from a main pipe 55a from the hydraulic pump 53 to the power cylinder 54, and a boost control provided in the bypass pipe 55d. A valve mechanism 62 is provided. The bypass pipe 55d branches from the main pipe 55a as described above, flows to the reservoir tank 56 without passing through the control valve mechanism 52 and the power cylinder 54, and returns from the reservoir tank 56 to the suction port 53a of the hydraulic pump 53. . The boosting control valve mechanism 62 is formed coaxially with the control valve mechanism 52 between the input shaft 221 and the valve sleeve 521 (see FIG. 1). As shown in the figure, the pressure increasing control valve mechanism 62 has six throttle valves C, D, E, F, G, and H formed in the oil passage.

  The boosting control valve mechanism 62 communicates the four ports such as the first port 621a, the second port 621b, the third port 621c, and the fourth port 621d, and the first port 621a and the second port 621b. 1 oil passage P12 ′, a second oil passage P13 ′ communicating with the first port 621a and the third port 621c, a third oil passage P24 ′ communicating with the second port 621b and the fourth port 621d, and a third port 621c And a fourth oil passage P34 ′ that communicates with the fourth port 621d.

  Two valves C and E are formed in the first oil passage P12 '. Two valves D and F are also formed in the second oil passage P13 '. A valve G is formed in the third oil passage P24 ', and a valve H is formed in the fourth oil passage P34'. As with the valves in the control valve mechanism 52, the throttle amount of these valves is changed in conjunction with the angular displacement of the input shaft 221 and the valve sleeve 521. Specifically, when the input shaft 221 rotates in the direction of arrow a in the figure and the input shaft 221 and the valve sleeve 521 are angularly displaced in one direction, the restriction of the valves A and A ′ in the control valve mechanism 52 is performed. As the opening degree increases, the throttle opening degree of the valves B and B ′ decreases, and in the boosting control valve mechanism 62, the throttle opening degree of the valves D, E, and G increases and the throttle opening degree of the valves C, F, and H increases. The opening becomes smaller.

  Contrary to the above, when the input shaft 221 rotates in the direction of arrow b in the figure and the input shaft 221 and the valve sleeve 521 are angularly displaced in the other direction, the valves B and B ′ in the control valve mechanism 52 As the throttle opening increases, the throttle opening of the valves A and A ′ decreases. In the boosting control valve mechanism 62, the throttle opening of the valves C, F, H increases and the valves D, E, G The throttle opening is reduced.

  The second port 621b and the third port 621c of the boosting control valve mechanism 62 communicate with each other through a communication oil passage 55e. A pressure increasing electromagnetic flow rate adjusting valve 63 is interposed in the communication oil passage 55e. The electromagnetic pressure regulating valve 63 for boosting is normally opened and is closed (or the opening degree is reduced) when the electric power steering device 40 is not operating normally or when the vehicle speed is low (during low-speed traveling). . The fourth port 621 d of the boost control valve mechanism 62 communicates with the reservoir tank 56. Further, the valve E and the valve F are designed to have a large channel cross-sectional area, and the valve G and the valve H are designed to have a small channel cross-sectional area.

  In the above configuration, when the electric power steering device 40 is operating normally, the boosting electromagnetic flow rate adjustment valve 63 is open. In this state, for example, when the input shaft 221 rotates in the direction of arrow a in the figure and causes an angular displacement with the valve sleeve 521, the valves D, E, and G of the boost control valve mechanism 62 are opened. C, F, and H are narrowed down. Therefore, the hydraulic oil that has reached the first port 621a of the boost control valve mechanism 62 from the hydraulic pump 53 through the bypass pipe 55d flows from the first port 621a to the third port 621c through the second oil passage P13 ′. . Here, when passing through the second oil passage P13 ′, it passes through the throttled valve F, but since the cross-sectional area of the valve F is originally large, the pressure does not increase so much even if hydraulic oil passes through the valve F. .

  The hydraulic oil that has reached the third port 621c tends to flow to the fourth oil passage P34 ′, but the valve H in the fourth oil passage P34 ′ is throttled, and this valve H is the original flow passage cross-sectional area. Is designed to be small, it cannot flow through the fourth oil passage P34 ′. Accordingly, the hydraulic oil flows through the communication oil passage 55e. Then, it passes through the pressure increasing electromagnetic flow rate adjusting valve 63 in the communication oil passage 55e and reaches the second port 621b. The hydraulic oil that has reached the second port 621b passes through the third oil passage P24 ', reaches the fourth port 621d through the valve G whose degree of opening is increased, and flows from there to the reservoir tank 56.

  As described above, in the state where the boosting electromagnetic flow rate adjustment valve 63 is open, almost no boosting occurs in the oil passage in the boosting control valve mechanism 62. For this reason, the amount of oil flowing through the bypass pipe 55d to the reservoir tank 56 through the boosting control valve mechanism 62 is relatively large, and as a result, the amount of oil flowing through the main valve 55a in the control valve mechanism 52 is relatively large. Decrease. When the amount of oil flowing through the control valve mechanism 52 decreases, the driving force generated in the power cylinder 54 also decreases. That is, the driving force generated in the power cylinder 54 is suppressed. Therefore, when the steering torque is small (when it is equal to or less than a predetermined value), an effective assist force is not generated from the hydraulic power steering device 50, and steering assist mainly using the assist torque from the electric power steering device 40 is performed. Further, when the steering torque increases, an effective assist force is also generated from the hydraulic power steering device 50. In this case, steering assist is performed by both the electric power steering device 40 and the hydraulic power steering device 50. In the above description, the case where the input shaft 221 rotates in the direction of the arrow a in FIG. 6 has been described. However, when the input shaft 221 rotates in the direction of the arrow b, the valve to be opened and the throttle valve are reversed. The amount of oil flowing to the mechanism 52 does not change.

  When the electric power steering device 40 does not operate normally and it is impossible to generate assist torque from the electric motor 44, the boosting electromagnetic flow rate adjustment valve 63 is closed. In this case, for example, when the input shaft 221 rotates in the direction of arrow b in FIG. 6, the valves C, F, and H of the boost control valve mechanism 62 are opened, and the valves D, E, and G are throttled. Therefore, the hydraulic oil that has reached the first port 621a of the boosting control valve mechanism 62 from the hydraulic pump 53 through the bypass pipe 55d reaches the second port 621b from the first port 621a through the first oil passage P12 '. Here, the valve E that is throttled when passing through the first oil passage P12 ′ passes through, but since the flow passage cross-sectional area of the valve E is originally large, the pressure does not increase so much when the hydraulic oil passes through the valve E. .

  The pressure oil (hydraulic oil) that has reached the second port 621b flows to the third oil passage P24 ′ or the communication oil passage 55e, but the boosting electromagnetic flow rate adjustment valve 63 in the communication oil passage 55e is closed, so that it operates. Oil must pass through the third oil passage P24 ′. Accordingly, the hydraulic oil reaches the fourth port 621d through the third oil passage P24 'and flows from there to the reservoir tank 56. At this time, the pressure is increased by the restriction of the valve G. Note that the boosting electromagnetic flow rate adjustment valve 63 does not have to be completely closed, and the flow rate of the communication oil passage 55e may be narrowed. In this case, the hydraulic oil also flows through the communication oil passage 55e, but the pressure is also increased in the communication oil passage 55e.

  In this way, when the boosting electromagnetic flow rate adjustment valve 63 is closed, the pressure is increased in the oil passage in the boosting control valve mechanism 62, so the amount of oil flowing through the boosting control valve mechanism 62 through the bypass pipe 55d. As a result, the amount of pressure flowing through the control valve mechanism 52 through the main pipe 55a is relatively increased. As the amount of oil flowing through the control valve mechanism 52 increases, the driving force generated in the power cylinder 54 also increases. Therefore, an effective assist force is generated from the hydraulic power steering apparatus 50 even when the steering torque is small. That is, when the electric power steering device 40 is not operating normally, an effective assist force can be generated from the hydraulic power steering device 50 with a small steering torque by closing the boosting electromagnetic flow rate adjusting valve 63. For this reason, a large steering torque is required until the assist force is generated from the hydraulic power steering device 50, so that the driver's steering operation is not burdened.

  As described above, the present embodiment suppresses the assist force output from the hydraulic power steering device 50 when the electric power steering device 40 is operating normally, and the electric power steering device 40 is not operating normally. Sometimes, as auxiliary force increasing means for increasing the assist force output from the hydraulic power steering device 50, the bypass pipe 55d branched from the main pipe 55a and the electric power steering apparatus provided in the bypass pipe are operating normally. Since the pressure boosting means (the pressure boosting control valve mechanism 62 and the pressure boosting electromagnetic flow rate adjusting valve 63) is provided in the absence of the electric power steering device 40, the driver is burdened with a small steering torque. Without effective hydraulic power steering device 50 It is possible to obtain the door force.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. FIG. 7 is a schematic view of the steering apparatus according to the present embodiment. The steering device 1 is provided with a hydraulic electromagnetic flow rate adjustment valve 71 as a throttle valve means in a main pipe 55 a between the hydraulic pump 53 and the power cylinder 54, and opens the hydraulic electromagnetic flow rate adjustment valve 71. The amount of oil supplied from the hydraulic pump 53 to the power cylinder 54 is adjusted by adjusting the degree adjusting means 72. Other configurations are the same as those of the steering apparatus 1 of the first embodiment. The hydraulic electromagnetic flow rate adjusting valve 71 is provided in the main pipe and downstream of the discharge port 53 b of the hydraulic pump 53 as shown in the figure. The hydraulic electromagnetic flow rate adjusting valve 71 is electrically connected to the opening degree adjusting means 72. By this opening degree adjusting means 72, the hydraulic electromagnetic flow rate adjusting valve 71 is controlled so as to decrease the opening degree when the electric power steering device 40 is operating normally, and to increase the opening degree when it is not operating normally. Is done.

  Therefore, when the electric power steering device 40 is operating normally, the amount of oil supplied from the hydraulic pump 53 side to the power cylinder 54 side is reduced by reducing the opening of the hydraulic electromagnetic flow rate adjusting valve 71. . As a result, the assist force output from the hydraulic power steering device 50 is reduced, and no effective assist force is generated from the hydraulic power steering device 50 with a small steering torque. For this reason, the electric power steering device 40 mainly generates assist torque in a region where the steering torque is small. On the other hand, when the steering torque increases, an effective assist force is also generated from the hydraulic power steering device 50. In this case, the assist torque and the assist force are transmitted from both the electric power steering device 40 and the hydraulic power steering device 50 to the steering amount. Is transmitted to the means, and steering assist is performed by both power steering devices. When the electric power steering device 40 is operating normally and the steering torque is large, the opening degree of the hydraulic electric flow control valve 71 is increased to reduce the amount of oil supplied to the power cylinder 54. May increase.

  When the electric power steering device 40 is not operating normally, the amount of oil supplied from the hydraulic pump 53 side to the power cylinder 54 side is increased by increasing the opening of the hydraulic electromagnetic flow rate adjusting valve 71. It becomes larger than the case. As a result, the assist force output from the hydraulic power steering device 50 becomes larger than in the above case, and an effective assist force can be generated from the hydraulic power steering device 50 with a small steering torque. For this reason, when the electric power steering device 40 is not operating normally, a large steering torque is not required until the assist force is effectively generated from the hydraulic power steering device 50, and the driver's steering operation is not burdened. .

  As described above, according to the steering device of the present embodiment, as the auxiliary force increasing means for increasing the steering auxiliary force output from the hydraulic power steering device 50 when the electric power steering device 40 is not operating normally, The hydraulic electromagnetic flow rate adjustment valve 71 as a throttle valve means inserted in the main pipe 55a of the power steering device 50 and the hydraulic electromagnetic flow rate adjustment valve 71 when the electric power steering device 40 is operating normally. An opening adjustment means 72 for adjusting the opening of the hydraulic electromagnetic flow adjustment valve 71 so as to increase the opening of the hydraulic electromagnetic flow adjustment valve 71 when the opening is reduced and is not operating normally; Therefore, the assist force of the hydraulic power steering apparatus 50 can be adjusted with a simple configuration.

  When the hydraulic pump 53 is driven by the engine, the rotational speed of the hydraulic pump 53 depends on the engine rotational speed. Therefore, when the engine rotational speed is low, such as during idling, the rotational speed of the hydraulic pump 53 is also low and discharged. The amount of oil is also reduced. For this reason, when the electric power steering device 40 is not operating normally and it is desired to generate a large assist force from the hydraulic power steering device 50 even when the steering torque is small, the hydraulic pressure is reduced to the target pressure when the engine speed is low. May not be able to be increased.

  FIG. 8 is a graph showing the relationship between the rotational speed of the hydraulic pump 53 and the discharge flow rate of the hydraulic oil discharged from the hydraulic pump 53. When the electric power steering device 40 is operating normally, the rotational speed and discharge flow rate of the hydraulic pump 53 change as shown by the solid line in the figure. In this case, since the assist torque from the electric power steering device 40 is also generated, the assist torque from the electric power steering device 40 is sufficient even if the rotational speed of the hydraulic pump 53 is low and the discharge amount of the pressure oil is small. Since the steering assist is performed, the driver's steering operation is not burdened. On the other hand, when the electric power steering device 40 is not operating normally, it is necessary to perform steering assist only with the hydraulic power steering device 50. At this time, if the engine is rotating at a low speed, the hydraulic power steering device 40 is hydraulic. Since the pump also rotates only at a low speed, there is a possibility that a sufficient assist force cannot be generated from the hydraulic power steering device 50. In order to prevent the occurrence of such a situation, in this embodiment, when the electric power steering device 40 is not operating normally, the hydraulic pump 53 can discharge the hydraulic oil that can generate the necessary assist force. As described above, the engine speed is set to be equal to or higher than a predetermined speed.

  In the example of FIG. 8, when it is determined that the discharge amount of the hydraulic pump 53 is necessary by the amount Q indicated by the alternate long and short dash line when the electric power steering device 40 is not operating normally, the engine Even during idling, the engine speed is controlled so that the hydraulic pump 53 rotates at a rotation speed (N rotation speed in the figure) that can discharge the discharge amount Q. Specifically, when it is determined that the electric power steering device 40 is not normal, this is detected by a warning signal or the like, and the detected signal is transmitted to a control device that performs engine control. Control as above. With this control, when the electric power steering device 40 is not operating normally, an effective assist force can be generated from the hydraulic power steering device 50 with a small steering torque even if the engine is idling.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. FIG. 9 is a schematic view of the steering apparatus according to the present embodiment. The steering device 1 includes a pump drive electric motor 73 that drives the hydraulic pump 53 and a drive control device 74 that controls the drive of the pump drive electric motor 73. Other configurations are the same as those of the steering apparatus 1 of the first embodiment. The electric motor 73 for driving the pump is driven and controlled so that it operates at a low rotational speed when the electric power steering device 40 is operating normally, and operates at a high rotational speed when it is not operating normally. The rotational speed is adjusted by the device 74, and the rotational speed of the hydraulic pump 53 is controlled by this rotational speed control.

  FIG. 10 is a graph showing the relationship between the rotation speed of the hydraulic pump 53 controlled by the rotation speed control of the pump drive electric motor 73 and the discharge amount of hydraulic oil discharged from the hydraulic pump 53. In the figure, a straight line portion indicated by a one-dot chain line and a two-dot chain line is a portion indicating the relationship between the rotational speed of the hydraulic pump 53 and the discharge amount when the electric power steering device 40 is operating normally, and is indicated by a solid line. The straight line portion shown is a portion showing the relationship between the rotational speed of the hydraulic pump 53 and the discharge amount when the electric power steering device 40 is not operating normally.

  When the electric power steering device 40 is operating normally, the rotational speed of the electric motor 73 for driving the pump is adjusted by the drive control device 74 according to the magnitude of the steering torque. In this case, for example, when the input steering torque is small as in the case of a steering operation during traveling, the hydraulic pump 53 rotates at a low rotational speed within the range of the steering torque small region indicated by the one-dot chain line in FIG. The drive control device 74 controls the rotation speed of the electric motor 73 for driving the pump. For this reason, the amount of oil discharged from the hydraulic pump 53 is also small, and no effective assist force is generated from the hydraulic power steering device 50, and the assist torque from the electric power steering device 40 mainly acts as a steering assist force.

  Further, when the electric power steering apparatus 40 is operating normally and the steering torque to be input is large, for example, when the electric power steering apparatus 40 is stationary, the hydraulic pump 53 is steered as indicated by a two-dot chain line in FIG. The drive control device 74 controls the rotation speed of the electric motor 73 for driving the pump so as to rotate at a medium rotation speed within the range of the large torque region. For this reason, the amount of oil discharged from the hydraulic pump 53 is increased, and the assist force is effectively generated also from the hydraulic power steering device 50. Therefore, a large steering assist force is generated by both the electric power steering device 40 and the hydraulic power steering device 50.

  Further, when the electric power steering device is not operating normally, the drive control device 74 drives the pump so that the hydraulic pump 53 rotates at a high rotational speed within the range of the EPS abnormal region indicated by the solid line in FIG. The number of rotations of the electric motor 73 is controlled. For this reason, even when the input steering torque is small, the hydraulic pump 53 rotates at a high speed and discharges a large amount of hydraulic oil. Therefore, an effective assist force is generated from the hydraulic power steering device 50 even when a small amount of steering torque is input. To do. As described above, when the electric power steering device 40 is not operating normally, the assist power is effectively generated from the hydraulic power steering device 50 even if the steering torque is small. Therefore, the assist force from the hydraulic power steering device 50 is obtained. It will not put a burden on the driver's steering operation.

  According to the steering device of the present embodiment, the hydraulic pump 53 is driven as auxiliary force increasing means for increasing the steering auxiliary force output from the hydraulic power steering device 50 when the electric power steering device 40 is not operating normally. When the pump driving electric motor 73 and the electric power steering device 40 are operating normally, the output rotational speed of the pump driving electric motor 73 is reduced and the electric power steering device 40 is not operating normally. In this case, since the drive control device 74 for adjusting the rotation speed of the pump driving electric motor 73 is provided so as to increase the output rotation speed of the pump driving electric motor 73, the hydraulic power steering device 50 with a simple configuration is provided. The assist force can be adjusted.

1 is a schematic view of a steering device according to a first embodiment of the present invention. 1 is a hydraulic circuit diagram of a steering device according to a first embodiment of the present invention. In the steering device concerning a 1st embodiment, it is a graph which showed the relation between steering torque and steering auxiliary power for every power steering device. FIG. 5 is a hydraulic circuit diagram of a steering device according to a second embodiment of the present invention. FIG. 10 is a hydraulic circuit diagram of a steering device according to a modification of the second embodiment. FIG. 6 is a hydraulic circuit diagram of a steering device according to a third embodiment of the present invention. It is the schematic of the steering device which concerns on 4th Embodiment of this invention. It is a graph showing the relationship between the rotation speed of the hydraulic pump and the discharge amount in the steering device according to the fourth embodiment. It is the schematic of the steering device which concerns on 5th Embodiment of this invention. It is a graph showing the relationship between the rotation speed of the hydraulic pump and the discharge amount in the steering device according to the fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steering device, 11 ... Steering handle, 20 ... Steering shaft (steering amount transmission means), 210 ... First steering shaft, 211 ... First shaft, 212 ... Second shaft, 220 ... Second steering shaft, 221 ... input shaft, 221a ... wing portion, 222 ... output shaft, 30 ... steering shaft (steering amount transmission means), 40 ... electric power steering device, 41 ... first torsion bar (first torsion bar), 42a, 42b DESCRIPTION OF SYMBOLS ... Detection means, 43 ... Control device, 44 ... Electric motor, 50 ... Hydraulic power steering device, 51 ... Second torsion bar (second torsion bar), 51 ... Hydraulic pump, 52 ... Control valve mechanism, 521 ... Valve sleeve 53 ... Hydraulic pump, 54 ... Power cylinder (hydraulic actuator), 55a ... Main piping, 55d ... Bypass piping, 55e ... Communication oil passage, 58 ... Hydraulic reaction force mechanism Reaction force generating means), 58a ... Hydraulic reaction force chamber, 59 ... Reaction force electromagnetic flow rate adjusting valve (reaction force control means, pressure release means), 62 ... Pressure increase control valve mechanism (pressure increase means), 63 ... Pressure increase electromagnetic Flow rate adjusting valve (pressure-increasing means) 71 ... Hydraulic electromagnetic flow rate adjusting valve (throttle valve means), 72 ... Opening adjusting means, 73 ... Electric motor for driving the pump, 74 ... Drive controller (rotation speed adjusting means)

Claims (10)

In a vehicle steering apparatus having a steering amount transmission means for transmitting a steering operation amount of a steering handle to a steered wheel,
An electric motor that generates a rotational driving force and transmits the generated rotational driving force to the steering amount transmission means as a steering assist force, and a rotational driving force generated by the electric motor based on a steering force acting on a steering handle. An electric power steering device comprising control means for controlling;
A hydraulic pump that discharges hydraulic oil; a hydraulic actuator that generates a driving force by supplying and discharging hydraulic oil discharged from the hydraulic pump; and that transmits the generated driving force to the steering amount transmission unit as a steering assist force; The hydraulic actuator is provided in a main pipe that communicates the hydraulic pump and the hydraulic actuator, and when the steering force acting on the steering handle is less than a predetermined value, the hydraulic actuator does not generate a driving force and exceeds a predetermined value. A steering apparatus comprising: a hydraulic power steering apparatus including a control valve mechanism that adjusts an amount of oil supplied from the hydraulic pump to the hydraulic actuator so as to generate a driving force. The steering apparatus according to claim 1, wherein
When the steering force of the steering wheel is less than the predetermined value, the electric power steering device mainly transmits a steering assist force to the steering amount transmission means,
The steering device according to claim 1, wherein when the steering force of the steering wheel is equal to or greater than the predetermined value, both the electric power steering device and the hydraulic power steering device transmit a steering assist force to the steering amount transmission means. The steering apparatus according to claim 1 or 2,
The electric power steering device is attached to the steering amount transmission means so as to be twisted by a steering operation of a steering handle, and has a first torsion bar having a predetermined lateral elastic coefficient and a torsion amount of the first torsion bar. Detection means for detecting the steering force acting on the steering wheel based on the control means, the control means controls the rotational driving force generated by the electric motor based on the steering force detected by the detection means,
The hydraulic power steering device includes a second torsion bar attached to the steering amount transmitting means so as to be twisted by a steering operation of a steering handle, and having a lateral elastic coefficient larger than the predetermined lateral elastic coefficient, The valve mechanism controls the amount of oil flowing from the hydraulic pump to the hydraulic actuator so that the amount of hydraulic oil corresponding to the amount of twist of the second torsion bar is supplied from the hydraulic pump to the hydraulic actuator. A steering device. The steering apparatus according to any one of claims 1 to 3,
One of the reaction force generating means that generates a reaction force that opposes the steering force and transmits the generated reaction force to the steering amount transmitting means, and the electric power steering device or the hydraulic power steering device operates normally. And a reaction force control means for controlling the reaction force generated by the reaction force generation means so that the reaction force transmitted to the steering amount transmission means is reduced when not. The steering apparatus according to claim 4, wherein
The reaction force generating means is a hydraulic reaction force mechanism that generates a reaction force by the pressure of hydraulic oil discharged from the hydraulic pump,
The steering apparatus according to claim 1, wherein the reaction force control means is a pressure release means for releasing a pressure obtained by the hydraulic reaction force mechanism when the electric power steering apparatus is not operating normally. The steering apparatus according to any one of claims 1 to 3,
At least one of the electric power steering device and the hydraulic power steering device is an auxiliary force that increases a steering auxiliary force when either the electric power steering device or the hydraulic power steering device is not operating normally. A steering apparatus comprising an increasing means. The steering apparatus according to claim 6, wherein
The auxiliary force increasing means is provided in the hydraulic power steering device, and suppresses the amount of oil supplied from the hydraulic pump to the hydraulic actuator when the electric power steering device is operating normally. A steering apparatus characterized by increasing the amount of oil supplied from the hydraulic pump to the hydraulic actuator when it does not operate normally. The steering apparatus according to claim 7, wherein
The auxiliary force increasing means is provided in a bypass pipe that branches from the main pipe and returns to the hydraulic pump without passing through the control valve mechanism and the hydraulic actuator, and the electric power steering device operates normally. A steering device, comprising boosting means for boosting the pressure when not. The steering apparatus according to claim 7, wherein
The auxiliary force increasing means reduces the opening of the throttle valve means when the throttle valve means inserted in the main pipe and the electric power steering device are operating normally, and the electric power steering A steering apparatus, comprising: an opening degree adjusting means for adjusting an opening degree of the throttle valve means so as to increase an opening degree of the throttle valve means when the apparatus is not operating normally. The steering apparatus according to claim 7, wherein
The auxiliary force increasing means reduces the output rotational speed of the pump driving electric motor when the electric power steering device is operating normally, and the pump driving electric motor for driving the hydraulic pump, A rotation speed adjusting means for adjusting the rotation speed of the electric motor for driving the pump so as to increase the output rotation speed of the electric motor for driving the pump when the electric power steering device is not operating normally. A steering device.

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