JPH01197172A - Power steering used for automobile - Google Patents

Abstract

PURPOSE:To restrain response delay in steering so as to improve steering performance by enabling supply of response correction pressure oil to a pair of reaction force chambers in a control valve through a pressure oil flow-in valve, respectively, and selectively controlling a pressure oil supply valve such that it increases steering force. CONSTITUTION:A control valve 12 provided for a power cylinder 11 generating assisting steering force is of oil pressure reaction type, and has a pair of reaction chambers 46, 47. In this case, a reaction force regulation passage 16 for communicating the chambers with each other is provided, on the way of which passage 16, a pressure difference regulating valve 17 is provided. Further, a variable throttle 21 is provided on an oil pressure piping 78 on the supply side on the upstream side of the control valve 12, and a flow regulating valve 23 is provided on a bypass connecting the upstream side of this variable throttle 21 to an oil pressure piping 79 on the return side. Also, a pair of pressure oil supply valve 19, 20 are provided on piping for introducing drive pressure oil to each reaction force chamber 46 or 47, and therefore selective controlling is performed for supplying correction pressure oil to the steering increasing side upon full steering of a handle.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to power steering used in automobiles, and particularly to power steering that improves response magnitude and response delay.

BACKGROUND ART In general, speed-sensitive power steering has become popular in automobiles.Increasing the sensitivity of this type of power steering reduces response delay and improves maneuverability, but the steering wheel angle The tire turning angle and yaw rate, that is, the magnitude of the response, increased and the steering tended to become sensitive.

OBJECTIVES AND PROBLEMS OF THE INVENTION The objectives and issues of this invention are to reduce the magnitude of response (gain) and response delay (phase) corresponding to steering wheel operation, suppress fluctuations in steering force, and maintain a neutral state of the steering wheel. The purpose of the present invention is to provide a power steering system for use in automobiles, which makes it possible to obtain a steering force that is sharply adjusted to the vehicle speed, and improves maneuverability and safety.

Summary of the structural invention related to the object and problem: Contents of the claimed invention In relation to the above-mentioned object and problem, the power steering used in the automobile of the present invention includes a power cylinder, a pair of reaction force chambers. A differential pressure adjustment system that is equipped with a control valve and an oil pump for steering, and the differential pressure between the reaction chambers reduces the flow rate of pressure oil flowing between the reaction chambers as the vehicle speed increases. Controlled by a valve, the response compensation pressure oil increases the steering force when the steering wheel is turned.
The pressure oil injection valve selectively injects the drive pressure oil into a pair of reaction force chambers of the control valve, and the driving pressure oil flowing from the oil pump discharge side to the control valve is controlled by the variable throttle. The flow rate is increased as the oil rises, and at that time, a portion of the driving pressure oil is transferred to the suction side of the oil pump through a flow regulating valve that is opened and closed by the differential pressure between the upstream and downstream sides of the variable restrictor. Equipped with a structure that is returned
The magnitude of the response can be adjusted by adjusting the differential pressure between the pair of reaction force chambers according to the vehicle speed, and by selectively injecting response correction pressure oil into the pair of reaction force chambers according to the steering wheel operation. The power is controlled in a small amount and is supplied to the power cylinder as the vehicle speed increases.

By increasing the flow rate of drive pressure oil, response delays are minimized (controlled), fluctuations in steering force are suppressed, and the neutral state of the steering wheel is clearly maintained.

In addition, in the power steering used in the automobile of this invention, the magnitude of the response (gain) is determined by the ratio between the steering force and the yaw rate, and the delay (phase) of the response is determined by the ratio between the steering force and the yaw rate. Each is defined in phase with the yaw rate.

DESCRIPTION OF EMBODIMENTS Preferred embodiments of the power steering system for use in automobiles according to the present invention will be described below with reference to the drawings.

The figure schematically shows an embodiment 10 of a power steering system for use in a motor vehicle according to the invention applied to a truck.

This power steering 10 is manufactured as a linkage type that steers a pair of front wheels (not shown), and includes a knuckle arm (not shown), a drag link (not shown), and a link lever (not shown). , compensating rod (not shown), pitman arm (not shown),
It includes a steering gear box (not shown), a steering shaft (steering shaft, not shown), a steering wheel (steering wheel, not shown), and a pair of cylinder chambers 34 and 35. a control valve 12 with a pair of reaction chambers 46 and 47; and an oil pump 13 connected to the control valve 12 by a supply hydraulic line 78.
, the control valve 12 in the return hydraulic line 79
an oil reservoir 14 connected to the oil reservoir 14, a flow control valve arranged in the supply hydraulic line 78 between the oil pump 13 and the control valve 12;
Valve 15, reaction force adjustment passage 16, differential pressure adjustment valve 17, response correction hydraulic piping 18, pair of pressure oil injection valves 19, 20, variable throttle 21, variable throttle bypass 22, flow rate adjustment valve 23, and the input side. The output side of the vehicle speed sensor 25 and steering sensor 26 is connected to its differential pressure adjustment valve 17 and pressure oil injection valve 19.20.
, and a control unit 24 electrically connected to the variable throttle 21, and the control unit 24 inputs signals from the vehicle speed sensor 25 and the steering sensor 26 to adjust the differential pressure regulating valve 17.
and the pressure oil injection valve 19.20, the differential pressure regulating valve 17 adjusts the differential pressure between the reaction force chambers 46 and 47, and at the same time, the pressure oil injection valve 19.20 However, the response correction pressure oil is selectively injected into the reaction force chambers 46 and 47 to reduce the magnitude of the response.
The control unit 24 controls the vehicle speed sensor 2
A signal is input from 5 to control the current flowing through the variable throttle 21, and the variable throttle 21 cooperates with the flow rate adjustment valve 23 to control the cylinder chamber 34 of the power cylinder 11.
．． The flow rate of the driving pressure oil supplied to the drive pressure oil 35 is adjusted to reduce the delay in response.

The power cylinder 11 incorporates the control valve 12 and is connected to the cylinder boat 43, 44, 45 of the control valve 12. A cylinder body 30 having a cylinder bore 31 with an open oil boat 36,37;
a pair of cylinder chambers 3 fitted in a reciprocating manner and connected correspondingly to the oil boats 36, 37;
A piston 32 that defines a 4° 35 in the cylinder bore 31, and a piston rod fixed to the piston 32 and extending removably from both ends of the cylinder body 30 with both end sides corresponding to the outside. 33, and its cylinder body 30 is connected to its link.
The levers and their piston rods 33 are rotatably connected to the chassis frame (shown in the drawings).

Moreover, this power cylinder 11 has its cylinder chamber 3
4 oil boat 36 to its control valve 1
2 cylinder bow) 43. Communication path 80 connected to 45
．． 81 and the oil boat 37 of its cylinder chamber 35 is connected to the cylinder boat 44 of its control valve 12.
A communication path 82 is provided.

In the power cylinder 11 configured in this way,
The movement of the piston 32 causes the cylinder body 30
and a pair of front axles (not shown) vibrably connected to opposite ends of the front axle (not shown) through their link levers, drag links, and knuckle arms. The power cylinder 11 thus steers the pair of front wheels rotatably supported on the front axle.

The control valve 12 is configured as a hydraulic reaction type spool valve, is installed in the cylinder body 30 of the power cylinder 11, and connects the spool shaft 90 to the convensating rod.
The valve is operated by the steering wheel via the pitman arm, the steering gear box, and the steering shaft, and in the hydraulic circuit, the power cylinder 11 is connected to the oil pump 13 and the oil pump. It is arranged in the piping connecting the reservoir 14, that is, the supply side hydraulic piping 78, the return side hydraulic piping 79, and the communication path 80° 81.82, and controls the direction of the pressure oil discharged from the oil pump 13,
It supplies the power cylinder 11 and directs the pressure oil worked in the power cylinder 11 and returns it to the oil reservoir 14 on the suction side of the oil pump 13.

The control valve 12 has a valve body 38
and a spool 40 reciprocally slidably disposed in a spool bore 39 of the valve body 38, and the spool 40 is connected to the spool shaft 90, the convensating rod, the pitman arm, and the steering gear. switching the pressure oil that is slid back and forth in its spool bore 39 by its steering wheel via the box and steering shaft and flows into the pair of cylinder chambers 34, 35 of its power cylinder 11;
The switching action directs the pressure oil returned from the cylinder chamber 34,35 to the oil reservoir 14.

The valve body 38 has a spool bore 39 formed therein having a predetermined inner diameter and length, and a spool bore 39 formed therein at a predetermined distance on one side (the upper side in the figure). forming a pump boat 41 and a tank boat 42 connected to the spool 41 and tank boat 42, spaced approximately equally apart on the other side (the lower side in the figure) and connected to the spool
Three cylinder boats 43, 4 connected to the bore 39
It forms 4°45.

The pump boat 41 is connected to the discharge side of the oil pump 13 via a supply hydraulic line 78, and the tank boat 44 is connected to the return side hydraulic line 79.
The cylinder ports 43, 44, 45 are connected to the cylinder chambers 34, 35 of the power cylinder 11 via communication passages 80, 81, 82. has been done.

Additionally, the valve body 38 includes a pair of reaction boats 48, 49 within the spool bore 39 which are used to communicate reaction chambers 46, 47 respectively formed on opposite sides of the spool 40. is formed.

The spool 40 has bores 50.5 opened on both end faces.
1 and reciprocatingly slidably disposed in the spool bore 39, and as such fitted in the spool bore 39, the bore 50.51 is arranged within the spool bore 39 to The volumes of a pair of reaction force chambers 46 and 47 formed on both sides of the spool 40 are increased.

Also, when the spool 40 reciprocates within the spool bore 39, a pair of reaction forces supply pressure oil to either one of the reaction chambers 46, 47, depending on the sliding direction of the spool 40. It is equipped with a communicating bow 1-52.53.

In particular, the spool 40 is connected to the reaction force communication port 52 .
Regarding 53, spools spaced at predetermined intervals in the axial direction?
1i54.55.56 are formed on the outer peripheral surface.

Of course, the reaction force chamber 46 is located in the spool groove 55, 56.
, 47 are correspondingly opened, so that the reaction communication boats 52 .
53 is the spool accompanying the movement of the spool 40.
The position of the spool groove 55,56 in the bore 39 connects the cylinder port 44,45 to the reaction chamber 46, 47, and the spool groove 54 connects the pump port 41 to the cylinder. Contact port 43.

Further, the spool 40 extends through the valve body 38 and into the spool bore 39 such that the spool 40 is slid back and forth into the spool bore 39 in response to a steering operation. - Approximately the center of the spool (spool center) is connected to the tip of the shaft 90. Of course, the spool shaft 90 connects the rear end to the convensating rod.

So configured, and the supply side hydraulic piping 78
, return side hydraulic piping 79, and communication path 80°81.82
The control valve 13 located at
The valve body 38 is provided with correction hydraulic ports 57, 58 opened corresponding to the reaction chambers 46, 47.

The oil pump 13 is driven by an internal combustion engine (not shown) mounted on the truck, and its power
In order to supply pressurized oil to the cylinder 11, it is arranged in the supply hydraulic line 78 of the hydraulic circuit connecting the oil reservoir 14 to the pump port 41 of the control valve 12, and in the oil reservoir 14. The oil is sucked up and pressurized so that the amount of pressurized oil discharged is approximately proportional to the rotational speed of the internal combustion engine. Of course, the oil pump 13 is manufactured to have a similar structure to the oil pump used in existing power steering systems, and its explanation will be omitted.

The flow control valve 15 is connected in the hydraulic circuit to hydraulic piping connecting the control valve 12 to the oil pump 13 and oil reservoir 14, ie, supply hydraulic piping 78 and return hydraulic piping 79. It is located.

The flow control valve 15 is connected to a pump port 60 connected to the discharge side of the oil pump 13.
, the pump boat 41 of its control valve 12
a casing 59 having a control valve port 61 connected to the side and a return port 62 connected to the suction side of the oil pump 13; and an oil reciprocally slidably disposed within the casing 59.・The configuration includes a return control spool, which adjusts the flow rate of the drive pressure oil sent to the pump port 60 side, sends a predetermined flow rate to the control valve boat 61 side, and also controls the drive pressure oil. Excess flow of pressurized oil is returned from the return port 62 to the oil reservoir 14 via a control valve bypass 83.

Of course, the flow control valve 15 is manufactured to have a similar structure to the flow control valve used in existing power steering systems, and a detailed explanation of its structure will be omitted.

The reaction force adjustment passage 16 has one end connected to the reaction force port 48 and the other end connected to the reaction force boat 49, and these reaction force chambers 4
6 and 47 to each other, and its control valve 1
2, the reaction force chamber 4
6, 47 to allow pressure oil to move.

The differential pressure adjustment valve 17 is arranged in the reaction force adjustment passage 16 and adjusts the amount of pressure oil flowing between the reaction force chambers 46 and 47.
The pressure within these reaction chambers 46, 47 is adjusted.

The differential pressure regulating valve 17 has a valve body 63 having a spool chamber (not shown) and a pair of ports 64, 65 in communication with the spool chamber. The spool is arranged such that it can be slid back and forth, and the cross-sectional area of the passage within the spool chamber changes in response to the reciprocating movement of the spool.

Therefore, depending on the reciprocating sliding of the spool, the port
-64.65 is adjusted, in other words, the reaction force chamber 46 of the control valve 12
, 47 is adjusted.

Of course, the differential pressure regulating valve 17 is connected to the pair of bows 1-64.
．． The shape may be arbitrary as long as the flow rate of the pressure oil flowing between the holes 65 can be adjusted.

The differential pressure regulating valve 17 is opened and closed by an electric actuator 66. That is, the electric actuator 66
is connected to the spool of the differential pressure regulating valve 17 by a servo motor so as to reciprocate the spool of the differential pressure regulating valve 17 to change the cross-sectional area of the passage within the spool chamber.

Of course, the electric actuator 66 can have any form as long as it is electrically connected to a control unit 24, which will be described later, and causes the spool to reciprocate by the output current from the control unit 24. For example, a stepper motor or an electromagnetic coil could be used as the electric actuator 66.

The response correction hydraulic piping 18 has one end connected to the variable throttle 21.
connected to the supply side hydraulic piping 78 on the upstream side of the
Further, the correction hydraulic boat 5 is branched from the other end side into a pair of branch pipes 67 and 68, and the branch pipes 67 and 68 are formed in the valve body 38 of the control valve 12.
7.58, and flows through the supply hydraulic piping 78 on the upstream side of the variable throttle 21 to supply high-pressure drive pressure oil, that is, response correction pressure oil, to the reaction chamber of the control valve 12. 46.47 directly.

The pair of pressure oil injection valves 19 and 20 are electromagnetic type two-way control valves, which are arranged in the corresponding branch pipes 67 and 68, respectively, and the solenoid coils 69 and 70 are connected to the output circuit of the control unit 24. (not shown) and is driven by a current controlled by the control unit 24, from the supply hydraulic piping 78 on the upstream side of the variable throttle 21 to the reaction chamber of the control valve 12. The response correction pressure oil is selectively supplied to 46 and 47, and at the same time, the supply amount of the pressure oil is controlled.

The variable aperture 21 is controlled by an electric actuator (not shown).
The control valve 1 drives a needle (not shown) and determines the flow rate by adjusting the gap between the needle and orifice (not shown).
2 and the flow control valve 15 thereof, the oil is discharged from the oil pump 13, the flow rate is controlled by the flow control valve 15, and the flow rate is controlled by the control valve 1.
Control is performed such that the flow rate of the drive pressure oil flowing through the truck is increased in accordance with an increase in the traveling speed of the truck, that is, the vehicle speed. Of course, the electric actuator is a solenoid.
The variable diaphragm 21 is a coil that electrically connects the solenoid coil to the output circuit of the control unit 24 and is driven by a current controlled by the control unit 24 to control the flow control. The flow rate of the drive pressure oil flowing from the oil pump 13 to the control valve 12 via the valve 15 is adjusted so that the flow rate can be increased in accordance with the increase in vehicle speed.

The variable throttle bypass 22 connects the supply hydraulic line 78 upstream of the variable throttle 21 to the return hydraulic line 79, and controls the flow rate of the oil discharged from the oil pump 13 and controlled by the flow control valve 15. The controlled drive pressure oil can be returned to the oil reservoir 14.

The flow 181 valve 23 is connected to a valve bore 72 and a pump port 75 connected to one end of the valve bore 72.
and tank boat 76 and its valve bore 7
A valve body 71 with a pressure lead port 77 connected to the other end of the valve body 71 has a reciprocating sliding movement in its valve bore 72 to communicate and disconnect its pump boat 75 and tank boat 76. The poppet 73 is inserted into the valve bore 72 and the poppet 73 is inserted into the valve bore 72.
The pump boat 75 and the tank boat 76 are made to have a structure including a pressure regulating spring 74 disposed on the other end side of the valve bore 72 so as to be biased toward one end side. The variable throttle bypass 22 is connected to the variable throttle bypass 22 and the pressure lead port 77 is connected to the variable throttle 2 of the supply hydraulic line 78 with a pressure lead line 84.
It is connected to the downstream side of 1.

As such, its supply and return hydraulic piping 78.
The flow regulating valve 23 disposed in the variable restrictor my path 22 that connects the variable restrictors 79 to each other has a poppet 73 that reciprocates in the valve bore 72 due to the differential pressure between the upstream and downstream sides of the variable restrictor 21. The pump port 75 is opened and closed as the poppet 73 opens and closes.
is connected to the tank port 76 to return a portion of the drive pressure oil flowing from the oil pump 13 to the control valve 12 via the flow control valve 15 to the oil reservoir 14.

That is, the flow rate regulating valve 23 returns the oil from the upstream side of the variable throttle 21 to the oil reservoir 14 at the differential pressure between the upstream side and the downstream side of the variable throttle 21 according to the amount of throttle of the variable throttle 21. Adjust the flow rate of the driving pressure oil.

The control unit 24 has an input side electrically connected to a vehicle speed sensor 25 and a steering sensor 26, and
The output side is electrically connected to the electric actuator 66 of the differential pressure regulating valve 17, the solenoid coil 69.70 of the pressure oil injection valve 19.20, and the solenoid coil of the variable throttle 21, respectively, and the vehicle speed sensor 25 and A signal is input from the steering sensor 26, and in accordance with the input signal, the output current of each of the differential pressure regulating valve 17, the pressure oil injection valves 19, 20, and the variable throttle 21 is determined. The output current of the valve 19.20 also determines the energization time,
Each of the output currents is applied to the electric actuator 66, the solenoid coils 69, 70, and the solenoid coil of the variable throttle 21, and the cross-sectional area of the passage is changed in the differential pressure regulating valve 17. The pressure oil injection valves 19, 20 are selectively opened during the energization time, and the differential pressure regulating valve 17 and the pressure oil injection valves 19, 20
The variable aperture 21 adjusts the steering force, that is, reduces the magnitude (gain) of the response, while the variable aperture 21 changes the gap between the needle and the orifice to increase the oil reservoir 14. The flow rate adjustment valve 23, which adjusts the flow rate of the drive pressure oil returned to the engine, performs adjustment to reduce the response delay (phase).

Of course, the control unit 24 is comprised of input and output circuits, memory circuits, arithmetic circuits, control circuits, and a power supply circuit that shares the truck's battery (not shown).

In particular, the control unit 24 controls the reaction chamber of the control valve 12 so that an optimum value of power cylinder pressure corresponding to the vehicle speed is generated in the power cylinder 11 in relation to the truck. The ideal value of the differential pressure between 46 and 47 is input in advance, and the vehicle speed sensor 2
5, compares the calculated value with the optimum value, controls the output current flowing to the differential pressure regulating valve 17, and controls the reaction force chamber 46, 47 of the control valve 12. The power steering 10 is adapted to the vehicle speed by adjusting the passage cross-sectional area of the differential pressure regulating valve 17 so that the differential pressure between the two matches an ideal value inputted in advance.

Further, this control unit 24 is associated with the truck, and when the steering wheel is turned, the control unit 24 is connected to the truck.
When the response correction pressure oil is injected into the reaction force chamber 46, 47 of the valve 12 on the side where the steering force is increased, the energization time of the pressure oil injection valve 19, 20 corresponds to the injection time of the response correction pressure oil. The energization pattern to be determined must be input in advance. Of course, the energization time is determined in accordance with the rate of change of the steering force applied to the steering wheel, which is temporally calculated by the control unit 24.

This control unit 24 therefore controls its pressure oil injection valve 19.2 in response to a signal from its steering sensor 25.
In other words, when determining the output current that selectively flows to 0, in other words, the output current that flows to the side that increases the steering force in the pressure oil injection valve 19.20 is determined, and at the same time, the , the energization time of the output current flowing to the side that increases the steering force is determined in comparison with the energization pattern, and the output current for which the energization time has been determined is applied to the solenoid of the pressure oil injection valve 19, 20.・Flow the steering force of coil 69.70 to the side that increases it,
The pressure oil injection valve 19.20 only for the determined energization time.
The side for increasing the steering force of the power steering 10 is opened, and the steering force of the power steering 10 is increased when the steering wheel is turned.

Furthermore, this control unit 24 determines the output current flowing to the variable aperture 21 in accordance with the signal from the vehicle speed sensor 25, and directs the output current to the variable aperture 21.
1 solenoid coil, and as the vehicle speed increases,
The gap between the needle and the orifice in the variable throttle 21 is widened to increase the flow rate of the driving pressure oil flowing to the power cylinder 11 via the control valve 12, thereby reducing the response delay (phase). Then, the power steering 10 is adapted to the vehicle speed.

In that way, the control unit 24
In this power steering 10, the differential pressure regulating valve 17 and the pressure The oil injection valves 19 and 20 are controlled, and the variable throttle 21 is controlled so that a flow rate of drive pressure oil that matches the vehicle speed is obtained and response delay (phase) is corrected.

The vehicle speed sensor 25 detects the traveling speed of the truck, and is arranged on the output shaft of a transmission (not shown) mounted on the truck.

The steering sensor 26 detects the rotational direction and speed of the steering wheel, the steering force applied to the steering wheel, and is built into the steering wheel. Of course, this steering sensor 26 may also be arranged in relation to the steering wheel shaft.

Next, the operation of the power steering unit 10 described above will be described in relation to the driving state of the truck.When the internal combustion engine is operated, at the same time, the control unit 2
4 inputs signals from the vehicle speed sensor 25 and steering sensor 26, calculates them, and operates the electric actuator 66 of the differential pressure regulating valve 17 and the solenoid of the pressure oil injection valve 19, 20.
Since the current flowing through the coils 69 and 70 and the solenoid coil of the variable throttle 21 is controlled, the oil pump 13 is driven, and the driving pressure oil discharged from the oil pump 13 is controlled by the flow control. The flow rate is first adjusted by the valve 15, and then its variable throttle 2
1, the flow rate is adjusted by the variable throttle 21, the pressure is maintained at the pressure determined by the variable restrictor 21, and the fluid flows into the supply hydraulic piping 78 and is sent to the pump boat 41 of the control valve 12.
Further, a portion of the drive pressure oil is transferred to the oil reservoir 14 through the flow regulating valve 23 which is opened by the differential pressure between the upstream side and the downstream side of the variable throttle 21 and the variable throttle bypass 22 and the return side hydraulic piping 79. It will be returned after

As shown in the figure, if the spool 40 is placed in the neutral position, the driving pressure oil sent to the pump boat 41 is transferred from the tank boat 42 via the return side hydraulic piping 79. Oil reservoir 1
Returned to 4.

Of course, in this case, the control unit 24
A signal is input from the vehicle speed sensor 25 and the steering sensor 26, and the output current flowing to the electric actuator 66 of the differential pressure regulating valve 17 is controlled. It is in a position to adjust the differential pressure to obtain a hydraulic reaction force suitable for the vehicle speed, that is, it is in a position to control the magnitude of the response, and it also controls the pressure oil injection valve 19, 20 according to when the steering wheel is turned during steering. Flow the output current to the side where the force is to be increased, and press the pressure oil injection valve 1.
9. Open the side that increases the steering force of 20, and inject response correction pressure oil into the side that increases the steering force of the reaction force chambers 46 and 47 of the control pulp 12, and adjust the response when the steering wheel is turned during that steering operation. It also controls the output current flowing through the solenoid coil of the variable aperture 21, and changes the gap between the needle and the orifice according to the vehicle speed to create a drive that matches the vehicle speed. It is also in a position to obtain the flow rate of pressure oil, supply the flow-adjusted drive pressure oil to the power cylinder 11, and control the delay in response.

Therefore, the operation of adjusting the magnitude of the response of the power steering 10 when the truck runs while being steered will be described.

First, we will discuss the case where the differential pressure regulating valve 17 adjusts the differential pressure between the reaction force chambers 46 and 47 of the control pulp 12 to reduce the magnitude of the response of the power steering 10. If the truck is running at a low speed, the control unit 24 inputs a signal from the vehicle speed sensor 25, calculates according to the input signal, and compares it with the ideal value of the differential pressure input in advance, The output signal, i.e., the output current, is determined and the output current is applied to the electric actuator 66 of the differential pressure regulating valve 17, so that the electric actuator 66 is driven, and in the differential pressure regulating valve 17, the spool is The spool chamber is slid into the spool chamber to widen the passage cross-sectional area within the spool chamber.

In such conditions, the spool 40 of the control valve 12 is slid either side into the spool bore 39 by steering. If so, that spool 40
Depending on the sliding direction of the oil pump 13, the driving pressure oil discharged from the oil pump 13 is directed to either one of the cylinder chambers 34, 35 of the power cylinder 11 and the reaction chamber 46 of the control valve 12. 47.

For example, if the spool 40 is slid to the right in the figure, the pump boat 41 will pass through the spool groove 55 to the cylinder boat 44 and the tank boat 42 will pass through the spool groove 56. The driving pressure oil discharged from the oil pump 13 is sent to the cylinder chamber 35 of the power cylinder 11 through the communication passage 82, and the piston 32 is connected to the cylinder boat 45 through the communication passage 82. , the driving pressure oil in the cylinder chamber 34 of the power cylinder 11 is returned to the oil reservoir 14 via the communication passage 80, 81 and the return hydraulic piping 79.

As such, when drive pressure oil is supplied, a portion of the drive pressure oil is sent to the reaction chamber 46 via the reaction force communication boat 52 and the bore 50.

The reaction force during such steering is given by the oil pressure in the reaction force chamber 46, but as mentioned above, during low speed running, the passage cross-sectional area of the differential pressure regulating valve 17 is widened, so that The pressure oil in the reaction force chamber 46 is
6, and flows to the other reaction force chamber 47 without being extremely restricted by the differential pressure regulating valve 17.

Furthermore, when the spool 40 is slid in the above-mentioned direction, the tank boat 42 is connected to the spool groove 56, and the pressure oil in the reaction chamber 47 is passed through the return side hydraulic piping 79. is returned to its oil reservoir 14.

Therefore, the pressure drop due to the differential pressure regulating valve 17 becomes smaller, the pressure difference in the left and right reaction force chambers 46, 47 becomes smaller, and the pressure oil in the reaction force chamber 46 becomes larger due to the sliding movement of the spool 40. There is no resistance; in other words, steering at low speeds is performed with a small operating force. That is, the magnitude of the response, the so-called ratio of the steering force to the yaw rate, is adapted to this low-speed running and becomes small, improving running stability.

If the spool 40 of the control valve 12 is slid to the left in the figure, the pump boat 41 will be placed in the spool groove 54 and the tank boat 42 will be placed in the spool groove 55. The driving pressure oil discharged from the oil pump 13 is sent to the cylinder chamber 34 of the power cylinder 11 through the communication passage 80, and the piston 32 is slid to the left in the figure. The drive pressure oil in the cylinder chamber 35 of the power cylinder 11 is returned to its oil reservoir 14 via the communication passage 82 and the return hydraulic piping 79.

Contrary to the case described above, the pressure oil in the reaction force chamber 47 passes through the reaction force adjustment 1lfl path 16 and is sent to the reaction force chamber 46 without being extremely restricted by the differential pressure adjustment valve 17. The pressure oil in the reaction chamber 46 is connected to the bore 50 and the reaction communication boat 5.
2, the oil is returned to its oil reservoir 14 via the spool groove 55, the tank boat 42, and the return hydraulic line 79.

Therefore, as in the case described above, the pressure drop due to the differential pressure regulating valve 17 becomes smaller, the pressure difference between the left and right reaction force chambers 46 and 47 becomes smaller, and the pressure oil in the reaction force chamber 47 is reduced. There is no large resistance to sliding of the spool 40, and steering is performed with a small operating force. That is, the magnitude of the response, the so-called ratio of the steering force to the yaw rate, is adapted to this low-speed running and becomes small, improving running stability.

Furthermore, if the truck is traveling at high speed, the control unit 24 inputs a signal from the vehicle speed sensor 25 and performs calculations according to the input signal.
The output current is determined by comparing it with the ideal value of the reaction pressure inputted in advance, and the output current is sent to the weather actuator 66 of the differential pressure regulating valve 17.

Therefore, the electric actuator 66 is driven with the output current, and in the differential pressure regulating valve 17 the spool is slid into the spool chamber, the passage cross section in the spool chamber being adapted to the vehicle speed. narrowed.

As in the case of low-speed running described above, if the spool 40 of the control pulp 12 is slid to either side by steering, depending on the sliding direction of the spool 40,
The pressure oil is in the cylinder chamber 34 of the power cylinder 11.
．． 35, the piston 32 slides, and a part of the driving pressure oil is sent to either one of the reaction force chambers 46,
47, but since the cross-sectional area of the passage inside the spool chamber of the differential pressure regulating valve 17 is narrowed,
The pressure drop caused by the differential pressure regulating valve 17 increases, and the pressure difference between the left and right reaction force chambers 46 and 47 increases, and as a result, the pressure oil in one of the reaction force chambers 46 and 47 is This creates a large resistance to sliding.

As such, a relatively large operating force is required for steering during high-speed travel. That is, the magnitude of the response, the so-called
The ratio between the steering force and the yaw rate is adapted to this high-speed running and becomes small, improving running stability.

Furthermore, when this truck is parked, the traveling speed is zero, so the passage cross-sectional area is widened to the maximum in the differential pressure regulating valve 17, and the mutual pressure difference between the reaction chambers 46 and 47 is increased. becomes extremely small, and as a result, its setting is performed with extremely small operating force.

As described above, in the power steering 10, the magnitude of the response is controlled to be small in accordance with the vehicle speed.

Next, when the handle is turned, the pressure oil injection valve 19.2
0, the response compensation pressure oil is the control valve 1
In the reaction force chambers 46 and 47 of 2, the power is injected into the side that increases the steering force, and even when the steering wheel is turned, the power
A case will be described in which the magnitude of the response of the steering wheel 10 is reduced.

Therefore, if the steering wheel starts turning to the right from the neutral state, the right turning steering, that is, the direction of rotation of the steering wheel,
The rotation speed and the steering force applied to the steering wheel are sensed by the steering sensor 26, which converts them into electrical signals and provides them to the control unit 24, so that the control - The unit 24 calculates based on the input electric signal, determines the output current flowing to the pressure oil injection valve 19 that increases the steering force, and at the same time compares it with the energization pattern input in advance. Then, the energization time of the output current is determined, and the output current is passed through the solenoid coil 69 of the pressure oil injection valve 19 for the determined energization time to open the pressure oil injection valve 9.

Therefore, high-pressure response correction pressure oil passes through the response correction hydraulic piping 18 and its branch pipe 67, and from the upstream side of the variable throttle 21 of the supply hydraulic piping 78 to the reaction chamber 46 of the control valve 12. In this way, when the steering wheel starts to be turned, the response compensation pressure oil is injected into the control valve 1 so as to increase the steering force.
2, the spool 40 begins to slide gradually to the right from the neutral position in the figure, opening the boat opening of the pump boat 41 progressively wider through its spool groove 55. pump. boat 4
1 to its cylinder boat 44 and simultaneously connect the tank boat 42 to its cylinder boat 44 via its spool groove 56 so as to open the port opening of the tank boat 42 progressively wider. The driving pressure oil discharged from the oil pump 13 is gradually sent to the cylinder chamber 35 of the power cylinder 11 through the communication passage 82.
In the cylinder chamber 35, the oil pressure gradually rises, and the piston 32 begins to gradually slide to the right in the figure, and at the same time, the piston 32 in the cylinder chamber 34 of the power cylinder 11 begins to slide to the right. The drive pressure oil begins to be returned to the oil reservoir 14 via the communication passage 80.81 and the return hydraulic line 79.

In this case, since the control valve 12 is incorporated into the cylinder body 30 of the power cylinder 11, the piston 32 is moved into the cylinder bore so as to follow the movement of the spool 40. 31 and the movement of the power cylinder 11 with such movement of the piston 32 is fed back to the control valve 12.

Therefore, when the spool 40 stops, the piston 3
2 is moved into its cylinder bore 31 by a distance corresponding to the travel distance of its spool 40 and stops, with its pump boat 41 and tank boat 42 being closed with its spool 40; The piston 32
is kept in a slid position to the right in the figure, i.e. its power cylinder 11 is kept in an extended position.

In this way, the drive pressure oil is supplied to the power cylinder 11, so that even when the steering wheel begins to turn to the right, the power cylinder 11 receives an increased steering force. , in this power cylinder 11, the magnitude of the response is controlled to be small.

Also, as the drive pressure oil begins to be supplied, a portion of the drive pressure oil is also sent to the reaction chamber 46 via the reaction communication boat 52 and bore 50 .

In this way, even when the response correction pressure oil is being injected into the reaction force chamber 46 of the control valve 12, the steering wheel is further turned to the right, and on the other hand, the subur 40 Since the movement of the power cylinder 11 by the piston 32, which is slid into the cylinder bore 31 following the movement of the power cylinder, continues to be fed back to the control valve 12, the control valve At 12, the spool 40 subsequently opens the port openings of the pump port 41 and cylinder port 44 wide open, and simultaneously opens the port openings of the tank port 42 and cylinder port 45 wide open. a spool shaft 90 driven by the steering wheel via the steering shaft, steering gear box, pitman arm, and compensating rod to open the aperture wide;
Slided further to the right into its spool bore 39, its pump port 41 and cylinder port 44 communicate with each other via a spool groove 55 of its spool 40, and at the same time its tank port 42 and cylinder port - The port 45 is connected to the spool groove 5 of the spool 40.
The driving pressure oil discharged from the oil pump 13 begins to be supplied in large quantities to the cylinder chamber 55 of the power cylinder 11 through the communication passage 82, and the piston 32 In order to follow the movement of the spool 40, the cylinder chamber 34 of the power cylinder 11 is further slid to the right in the figure.
The drive pressure oil within begins to be returned in bulk to its oil reservoir 14 via the communication passage 80.81 and the return hydraulic line 79.

After the energization time has elapsed, the solenoid coil 6
9 is cut off by its control unit 24, its pressure oil injection valve 19 is closed, and the output current flowing through its response compensation hydraulic line 18 and its branch pipe 67 is turned off on the upstream side of its variable throttle 21. The supply side hydraulic piping 7
8 into the reaction force chamber 46 of the control valve 12 is stopped, so that the spool 40 is connected to the steering shaft, steering gear box, pitman The spool shaft 90, which is driven by the steering wheel via the arm and the compensating rod, is further slid to the right, and as the spool 40 moves, the piston 32 of the power cylinder 11 also moves. Further, the driving pressure oil discharged from the oil pump 13 and supplied to the cylinder chamber 35 causes the power cylinder 11 to be further slid to the right in the figure, and the power cylinder 11 is fully extended, and the link・A front wheel axle (not shown) is rotated around a king bin (not shown) via levers, track links, and knuckle arms, and the front wheels rotatably supported on the front wheel axle are rotated to the right. is steered by.

When the steering wheel starts to return toward the neutral position, that is, when the steering wheel starts turning to the left, the left turn steering is sensed by the steering sensor 26, which converts it into an electrical signal. The control unit 24 calculates based on the input electric signal, and when the steering force increases, the pressure oil flows to the pressure oil injection valve 20. At the same time as determining the output current, the energization time of the output current is determined by comparing it with a pre-input energization pattern, and the solenoid coil 7 of the pressure oil injection valve 20 is operated for the determined energization time.
0, and the pressure oil injection valve 20 is opened.

Therefore, the high-pressure response correction pressure oil flows from the upstream side of the variable throttle 21 of the supply side hydraulic piping 78 to the reaction force chamber 47 of the control valve 12 via the response correction hydraulic piping 18 and its branch pipe 68. As such, at the beginning of the steering wheel return turn, the response compensation pressure oil is applied to the control valve 12 to increase the steering force so that the spool 40 The spool groove begins to slide gradually from the neutral position shown in the figure toward the left side, and in the opposite direction to the above case, the spool groove gradually opens the port opening of the pump port 41 widely. 54 to communicate the pump boat 41 with the cylinder boat 43, and at the same time cause the boat opening of the tank boat 42 to open progressively wider in the opposite direction to that in the previous case. , connecting the tank boat 42 to the cylinder boat 44 via the spool groove 55;
Accordingly, the driving pressure oil discharged from the oil pump 13 is gradually sent to the cylinder chamber 34 of the power cylinder 11 through the communication passage 80, and in the cylinder chamber 34, the rise of the oil pressure is gradual. , the piston 32 begins to gradually slide to the left in the figure, and at the same time the power cylinder 1
The driving pressure oil in the cylinder chamber 35 of No. 1 is transferred to the oil reservoir 1 through the communication passage 82 and the return hydraulic piping 79.
It starts to go back to 4.

In this way, the driving pressure oil is supplied to the power cylinder 11 so that even when the steering wheel starts to be returned, that is, to start turning to the left, the power cylinder 11 is supplied with the drive pressure oil. The steering force is increased, and the magnitude of the response in this power cylinder 11 is controlled to be small.

In addition, when the driving pressure oil starts to be supplied in this manner, a portion of the driving pressure oil passes through the communication passage 80, 81, the spool groove 56, the reaction force communication boat 53, and the bore 51, and enters the reaction force chamber. It will also be sent to 47.

Then, even when the response correction pressure oil is being injected into the reaction force chamber 47 of the control valve 12, the steering wheel is further turned to the left, while the power As the movement of the cylinder 11 continues to be fed back to the control valve 12, the spool 40 continues to be connected to the pump boat 41, the tank, in the opposite direction.・Boat 42
, and driven by its steering wheel via its steering shaft, steering gear box, pitman arm, and compensating rod to cause the boat opening of the cylinder boat 43.44 to be opened wide. The spool shaft 90 is slid back into its spool bore 39 further to the left, in other words towards the neutral position of the figure, and its pump boat 41 and cylinder boat 43 are 40 are connected to each other via spool grooves 54, and at the same time, the tank boat 42
The cylinder boats 44 and 44 are connected to each other via the spool grooves 55 of the spools 40, and the driving pressure oil discharged from the oil pump 13 is transferred to the communication path 80.
The piston 32 then slides further to the left in the figure to follow the movement of the spool 40, and reaches the so-called neutral position in the figure. At the same time, the driving pressure oil in the cylinder chamber 35 of the power cylinder 11 begins to be returned in large quantities to the oil reservoir 14 via the communication passage 82 and the return hydraulic piping 79.

When the energization time for returning the handle has elapsed, the output current flowing through the solenoid coil 70 is cut off by the control unit 24, the pressure oil injection valve 20 is closed, and the response correction oil pressure is The response correction pressure oil being injected into the reaction force chamber 47 of the control valve 12 from the supply side hydraulic pipe 78 upstream of the variable throttle 21 via the pipe 18 and its branch pipe 68 is stopped. Therefore, the spool 40 is shown in the figure with only the spool shaft 90 being driven by the steering wheel via the steering shaft, steering gear box, pitman arm, and compensating rod. In other words, with only the steering force applied by the steering wheel, the piston 32 is slidably returned to the neutral position shown in the figure, and the piston 32 is also moved to the oil position by following the movement of the spool 40. The driving pressure oil discharged from the pump 13 and supplied to the cylinder chamber 34 via the supply side hydraulic piping 78 and the communication passage 80 simultaneously flows through the communication passage 82 and the return side hydraulic piping 79.
from the cylinder chamber 35 to the oil reservoir 1 via
Since the drive pressure oil returned to each power cylinder 1 is substantially exhausted, the power cylinder 1 is returned to the position shown in the figure.
1 is retracted as a whole, and the front wheel axle is rotated around the king bin via its link lever, drag link, and knuckle arm, and the front wheel, which is rotatably supported on the front wheel axle, moves straight. be returned.

Subsequently, if the other steering wheel thus returned to the neutral state is continuously turned further to the left from its neutral state, in this case its steering sensor 26 is turned, since the steering direction is the same. The control unit 24, which receives an electrical signal from the control unit 24, does not send an output current to the solenoid coil 69.70 of the pressure oil injection valve 19.20.

Therefore, when the steering wheel is steered to the left, the pressure oil injection valve 19,20 is in a closed state, and the high pressure response correction pressure oil is supplied to the variable throttle 21 of the supply side hydraulic pipe 78. The control valve 12, i.e. the spool 40, is not supplied to any of the reaction chambers 46, 47 of the control pulp 12 from the upstream side of the steering shaft, steering gear box. , the pitman arm, and its spool shaft driven by its steering wheel through a convensing” rod 9
0 alone, i.e. with only the steering force applied by the steering wheel, the pump boat 41 is slid to the left into the spool bore 39 and, with the movement of the spool 40, the pump boat 41 opens the boat opening. The cylinder boat 43 is connected via the spool groove 54 so as to be opened wide, and at the same time, the tank boat 4
2 is connected to its cylinder boat 44 via its spool groove 55 so as to open the boat opening widely;
The driving pressure oil discharged from the oil pump 13 is
The driving pressure oil in the cylinder chamber 35 of the power cylinder 11 begins to be sent to the cylinder chamber 34 of the power cylinder 11 via the communication passage 80, and at the same time, the driving pressure oil in the cylinder chamber 35 of the power cylinder 11 is transferred to the communication passage 82 and the return side hydraulic pressure. begins to be returned to its oil reservoir 14 via line 79, so that its power
The piston 32 of the cylinder 11 is connected to its cylinder bore 3
1, the power cylinder 11 begins to slide to the left from the neutral position in the figure, and the power cylinder 11 begins to further retract as a whole.

As such, when the power cylinder 11 begins to retract, the link lever, drag link, knuckle
The front axle begins to rotate to the left around the king bin via the arm, and the front wheels rotatably supported on the front axle begin to be steered to the left.

Further, when the driving pressure oil discharged from the oil pump 13 begins to be supplied to the cylinder chamber 34 of the power cylinder 11, a portion of the driving pressure oil is transferred to the communication passage 80.
, 81, the spool groove 56, the reaction force communication boat 53, and the bore 51 to the reaction force chamber 47 thereof.

Furthermore, if the steering wheel is steered to the left, the movement of the power cylinder 11 continues to be fed back to the control valve 12 in this case as well, so that in this control pulp 12 , the spool 40 is moved by steering forces applied by the steering wheel to widen (keep open) the port openings of the pump boat 41 and tank boat 42 in the left direction.
9 continues to slide to the left, and its pump boat 4
1 and the cylinder boat 43 have their spool grooves 54
At the same time, the tank boat 42 and the cylinder boat 44 are communicated with each other via the spool groove 55, and the driving pressure oil discharged from the oil pump 13 is A large amount of the driving pressure oil in the cylinder chamber 35 of the power cylinder 11 is sent to the cylinder chamber 34 of the power cylinder 11 through the communication passage 80, and at the same time, the driving pressure oil in the cylinder chamber 35 of the power cylinder 11 is transferred to the communication passage 82 and the return side hydraulic pressure. The bulk is returned to its oil reservoir 14 via line 79.

Accordingly, the piston 3 of the power cylinder 11
2 is further slid to the left in the figure, i.e.
The power cylinder 11 will generally be further compressed, so that the front axle will be further rotated to the left around its king pin via its link lever, drag ring, and knuckle arm. , the front wheel rotatably supported on the front wheel axle is steered significantly to the left.

If steering is performed subsequently, the power steering 1.0 performs an operation similar to that described above.

Next, the response correction operation of the power steering 10 according to the vehicle speed of the truck will be described.

Now, if the truck is running at a low speed, the control unit 24 inputs a signal from the vehicle speed sensor 25, performs calculations according to the input signal, and determines the output signal, that is, the output current. Since the output current is passed through the solenoid coil of the variable throttle 21, the needle of the variable throttle 21 is connected to the solenoid coil of the variable throttle 21.
Driven by a coil, the gap between its needle and its orifice is narrowed.

Therefore, the flow rate of the driving pressure oil flowing into the pump boat 41 of the control valve 12 is reduced, and at the same time, the differential pressure between the upstream side and the downstream side of the variable throttle 21 increases, and the flow rate regulating valve 23 is a drive system in which the pressure of drive pressure oil flowing into one end of the valve bore 72 from the pump boat 75 flows into the other end of the valve bore 72 from the pressure lead boat 77. higher than the pressure of the pressurized oil, the poppet 73 is slid into the valve bore 72 from one end to the other against the pressure regulating spring 74, and the tank boat 76 is opened wide. The driving pressure oil flowing into the variable throttle 21 is returned in large quantities to the oil reservoir 14 via the variable throttle bypass 22 and the return hydraulic piping 79.

In such a condition, if the spool 40 of the control valve 12 is slid either way into the spool bore 39 by steering, the oil The driving pressure oil discharged from the pump 13 is supplied to either one of the cylinder chambers 34, 35 of the power cylinder 11, and at the same time, a portion of the driving pressure oil is supplied to the reaction force communication boat 52, 53.
It is also supplied to either one of the reaction force chambers 46, 47 of the control valve 12 through one of the two.

At this time, the flow rate of the drive pressure oil is
Since the cylinder chamber 34 is reduced by
．． The flow rate of the driving pressure oil supplied to either one of the pistons 35 is also reduced, and the movement of the piston 32 is slowed down to adapt to the low-speed running, in other words, response delay, so-called
The phase between the steering force and the yaw rate is adapted to the low speed running and reduced, improving maneuverability.

Contrary to the above, if the spool 40 of the control valve 12 is slid either way into the spool bore 39 by steering, the drive pressure oil is transferred to the cylinder chamber of the power cylinder 11. 34, 35, and simultaneously a portion of the drive pressure oil is supplied to the reaction chamber 46 of the control valve 12,
47.

At this time as well, the movement of the piston 32 is adapted to the low speed running and slows down, in other words, response delay, so-called, the phase between the steering force and the yaw rate is adapted to the low speed running and is reduced. and improves maneuverability.

Furthermore, if the truck is traveling at high speed, the control unit 24 inputs a signal from the vehicle speed sensor 25 and performs calculations according to the input signal.
Since the output signal, that is, the output current is determined, and the output current is passed through the solenoid coil of the variable aperture 21,
In the variable throttle 21, the needle is moved by the solenoid coil to widen the gap between the needle and the orifice.

Therefore, the flow rate of the drive pressure oil flowing into the pump bow 41 of the control valve 12 is increased, and at the same time, the differential pressure between the upstream speed and the downstream speed of the variable throttle 21 is reduced, and the flow rate regulating valve 23 is reduced. In this case, the pressure of driving pressure fluid flowing into one end of the valve bore 72 from the pump boat 75 flows into the other end of the valve bore 72 from the pressure lead boat 77. As the pressure of the drive pressure oil approaches, the poppet 73 is slid into the valve bore 72 from one end to the other by the regulating spring 74, and the tank boat 76 is narrowly opened and the variable throttle The drive pressure oil flowing to 21 is returned in small quantities to the oil reservoir 14 via the variable throttle bypass 22 and the return hydraulic line 79.

In such a condition, if the spool 40 of the control valve 12 is slid either way into the spool bore 39 by steering, the oil The driving pressure oil discharged from the pump 13 is supplied to either one of the cylinder chambers 34, 35 of the power cylinder 11, and at the same time, a portion of the driving pressure oil is supplied to the reaction force communication boat 52, 53.
It is also supplied to either one of the reaction force chambers 46, 47 of the control valve 12 through one of the two.

At that time, the flow rate of the drive pressure oil is increased by the variable throttle 21, so that the cylinder chamber 34.35
The flow rate of the driving pressure oil supplied to one of the two is also increased, and the movement of the piston 32 is adapted to the high-speed running and becomes faster.In other words, the response delay, so-called, between the steering force and the yaw rate is The phase is reduced to suit its high speed running and improves maneuverability.

Contrary to the above, if the spool 40 of the control valve 12 is slid into the spool bore either way by steering, the drive pressure oil is transferred to the cylinder chamber 34 of the power cylinder 11. At the same time, a portion of the drive pressure oil is supplied to either of the reaction chambers 46, 47 of the control valve 12 in large quantities.

At this time, the movement of the piston 32 is adapted to the high-speed running and becomes faster. In other words, the response delay, so-called phase between the steering force and the yaw rate, is adapted to the high-speed running and is reduced. , maneuverability is improved.

Of course, the operation of the power steering 10 with respect to the vehicle speed described above is the same as that of the power steering 10 described above.
This is done simultaneously with the adjustment of the magnitude of the response.

Although the power steering 10 described above was manufactured as a linkage type, this power steering 10 can be manufactured in various types such as an integral type and a semi-integral type.

Conveniences and Benefits of the Invention From the foregoing, it can be seen that the power steering and differential steering systems used in the automobile of this invention are superior to the power steering and differential steering systems used in automobiles that have already been proposed and used. The steering is controlled
The differential pressure between the pair of reaction force chambers of the valve is controlled by a differential pressure regulating valve that reduces the flow rate of pressure oil flowing between the reaction force chambers as the vehicle speed increases. A pressure oil injection valve selectively injects the drive pressure oil into its reaction chamber to increase the steering force, and a variable restrictor controls the drive pressure oil flowing from the oil pump discharge side to its control valve to increase the vehicle speed. The flow rate is increased in accordance with the rise in the flow rate, and at that time, a portion of the driving pressure oil is applied to the oil pump by the flow Hl regulating valve, which is opened and closed by the differential pressure between the upstream and downstream sides of the variable restrictor. Since the power is returned to the suction side, in the power steering used in the automobile of the present invention, by adjusting the differential pressure between the reaction force chambers, the magnitude of the response to steering wheel operation is controlled to be small, that is, the vehicle speed is increased. As a result, the pressure difference between the reaction force chambers increases, the steering force increases, and the so-called steering wheel becomes heavier, and the magnitude of the response, in other words, the ratio between the steering force and the yaw rate decreases. In addition, when the steering wheel is turned, response correction pressure oil is injected into the side of the pair of reaction force chambers that increase the steering force, so that the drive pressure oil increases the power output.・By supplying more oil to the cylinder, the magnitude of the response is controlled to be smaller, improving maneuverability.Furthermore, by changing the flow rate of drive pressure oil supplied to the power cylinder, the delay in response to steering wheel operation is reduced. In other words, as the vehicle speed increases, the flow rate of the drive pressure oil supplied to the power cylinder is increased, and by increasing the flow rate of the drive pressure oil, the hydraulic pressure rises faster. °, the delay in response, in other words, the phase between the steering force and yaw rate is reduced, improving maneuverability.In addition, fluctuations in the steering force are suppressed, the neutral LQ of the steering wheel becomes clearer, and the vehicle very useful for

Relationship Between the Invention and Specific Examples As described above, the specific examples of the present invention described with reference to the drawings will make various design modifications and changes obvious to those who have ordinary knowledge in the technical field to which this invention pertains. Modifications are easy to make, and furthermore, the content of the invention is essential to the establishment of the invention for accomplishing the task of the invention, and is derived from the technical essence of the invention, which is the nature of the invention. , and can be easily replaced by a form that is objectively recognized as incorporating it.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a schematic diagram showing a specific example of a power steering system used in a vehicle according to the present invention applied to a truck. 11... Power cylinder, 12... Control pulp, 13... Oil pump, 14... Oil reservoir, 15... Flow control pulp, 16... Reaction force adjustment passage , 17... Differential pressure regulating valve,
18... Response correction hydraulic piping, 19.20... Pressure oil injection valve, 21... Variable throttle, 22... Variable throttle bypass, 23... Flow IJkUfQM valve, 24... Control unit , 25...Vehicle speed sensor, 26...
Steering sensor, 78..., supply side hydraulic piping, 79...
Return side hydraulic piping. Patent applicant Hino Motors Co., Ltd.66

Claims (1)

[Claims] In a steering vehicle equipped with a power cylinder, a control valve having a pair of reaction force chambers, and an oil pump, the differential pressure of the reaction force chambers increases as the vehicle speed increases. It is controlled by a differential pressure regulating valve that reduces the flow rate of pressure oil flowing between the force chambers, and a pressure oil injection valve controls a pair of control valves so that the response compensation pressure oil increases the steering force when the steering wheel is turned. is selectively injected into the reaction chamber, and the control valve is injected from the discharge side of the oil pump.
The drive pressure oil flowing into the valve is increased in flow rate according to the increase in vehicle speed by a variable throttle, and at that time, a portion of the drive pressure oil is opened and closed by the differential pressure between the upstream and downstream sides of the variable throttle. Power steering used in automobiles is characterized by the fact that the oil is returned to the suction side of the pump through a flow regulating valve.