JP2002145102A - Steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely achieve failsafe function with simple constitution, in a steering system capable of changing the ratio of the steering wheel angle to the steering amount depending on vehicle speed. SOLUTION: Rotation of an input shaft 4 caused depending on steering is transmitted to an output shaft 11 via a planetary gear mechanism 30. Rotation of the output shaft 11 is transmitted to wheels in a manner that the steering angle is changed by a steering gear. The rotation transmission ratio from the input shaft 4 to the output shaft 11 is changed by rotationally driving a component of the planetary gear mechanism 30 depending on the vehicle speed with an electric actuator 38. Relative rotational movement of the input shaft 4 and the output shaft 11 is converted into movement of a locking member 45 between the position for allowing and the position for stopping the rotation of the component of the planetary gear mechanism 30 rotated by the electric actuator 38. The locking member 45 is arranged at the position for allowing rotation when the relative rotational angle of the input and output shafts 4, 11 is a preset angle or less, and is arranged at the position for stopping rotation when exceeding the preset angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus capable of changing a ratio of a steering angle to a steering amount according to a vehicle speed.

[0002]

2. Description of the Related Art In a steering apparatus disclosed in Japanese Patent Application Laid-Open No. 11-1175, the rotation of an input shaft according to steering is transmitted to an output shaft via a planetary gear mechanism, and the rotation of the output shaft is transmitted to a steering gear. Thus, the steering angle is transmitted to the wheels so as to change, and the rotation transmission ratio from the input shaft to the output shaft is changed by driving the sun gear of the planetary gear mechanism by a motor according to the vehicle speed.

[0003] In the conventional steering device described above,
A deviation between the rotation angle of the input shaft and the rotation angle of the output shaft is detected by a sensor, and when the detected value exceeds a predetermined value, the solenoid actuator is operated. By the operation of the solenoid actuator, the rotor of the motor that drives the sun gear is connected to the output shaft side,
The rotation of the sun gear by the motor is prevented. Thus, when the deviation between the rotation angle of the input shaft and the rotation angle of the output shaft becomes excessive due to a failure of the motor or the like, the input shaft and the output shaft can be directly connected to provide a fail-safe function.

[0004]

In the above-mentioned conventional steering apparatus, a deviation between the rotation angle of the input shaft and the rotation angle of the output shaft is detected by a sensor, and whether or not the deviation exceeds a predetermined value is determined by a control system. By judging and controlling the solenoid actuator by the control system, the rotation of the sun gear by the motor is prevented. Therefore, when the sensor, the solenoid actuator, or the control system breaks down, there is a problem that the fail-safe function cannot be achieved.

An object of the present invention is to provide a steering device that can solve the above-mentioned problem.

[0006]

According to the present invention, the rotation of an input shaft according to steering is transmitted to an output shaft via a planetary gear mechanism, and the rotation of the output shaft is changed by a steering gear. The present invention is applied to a steering device capable of changing the transmission ratio of a rotation transmitted from an input shaft to an output shaft by transmitting the rotation to a wheel by rotating a component of the planetary gear mechanism by an electric actuator according to a vehicle speed. The present invention provides a lock member movable between a rotation permitting position and a rotation preventing position of a component of a planetary gear mechanism by the electric actuator, and a relative rotational movement of an input shaft and an output shaft of the lock member for movement of the lock member. The lock member is disposed at the rotation allowable position when the relative rotation angle of the input / output shaft is equal to or less than a predetermined set angle, and when the relative rotation angle exceeds the set angle, It is characterized in that it is arranged at a rotation preventing position. According to the configuration of the present invention, when the relative rotation angle between the input shaft and the output shaft exceeds the set angle due to a runaway of the electric actuator or the like, the relative rotation movement of the input / output shaft is converted into the movement of the lock member. Due to the movement, the lock member is displaced from the rotation allowing position of the component of the planetary gear mechanism by the electric actuator to the rotation preventing position. That is, by mechanically converting the excessive relative rotation of the input / output shaft into movement of the lock member, the rotation of the components of the planetary gear mechanism by the electric actuator is locked, and the rotation of the input shaft according to the driver's intention is prevented. Since the power can be transmitted to the output shaft, the fail-safe function can be reliably achieved.

In the planetary gear mechanism, a planetary gear meshing with a sun gear and a ring gear is held by a carrier, and a first planetary gear element which is one of the sun gear, the ring gear and the carrier is connected to the input shaft. A second planetary gear element, which is not connected to the input shaft in the sun gear, the ring gear, and the carrier, is connected to the output shaft, and is connected to the input / output shaft in the sun gear, the ring gear, and the carrier. An uncoupled third planetary gear element is rotatably driven by the electric actuator, and the electric actuator is controlled such that the rotation transmission ratio of the planetary gear mechanism from the input shaft to the output shaft changes according to the vehicle speed. A locking mechanism is provided, the locking member being in a rotation preventing position, the third planetary gear element Preferred blocking rotation. Further, the motion conversion mechanism includes a pressing portion that rotates together with one of the two shafts, a slider that rotates together with the other of the two shafts and is movable in the axial direction, and moves in the axial direction toward the slider. An elastic member that imparts elasticity, the pressing portion and the slider are arranged at positions where they are pressed against each other by the relative rotation of both shafts, and the slider can move in the other axial direction against the elasticity by the pressing. As described above, the pressing portion and the slider are pressed against each other via the guide surface inclined with respect to the axial direction and the radial direction of the input shaft, and the slider is moved in the other axial direction by the relative rotation of both shafts exceeding the set angle. Is moved from the restriction position to the restriction release position, and the locking member moves toward the rotation preventing position. The lock member is held at the rotation allowable position by the slider at the restriction position, and moves to the rotation inhibition position by the action of the elastic force due to the movement of the slider to the restriction release position. Is preferred. Thus, when the relative rotation angle of the input / output shaft becomes excessive, the fail-safe function can be reliably achieved with a simple configuration.

[0008] It is preferable that a switch is provided to operate in conjunction with the movement of the lock member from the rotation permitting position to the rotation preventing position, thereby cutting off the power supply to the electric actuator. This makes it possible to cut off the power supply to the electric actuator by utilizing the movement of the lock member for achieving the fail-safe function. Therefore, when the rotation of the components of the planetary gear mechanism by the electric actuator is prevented by the lock member, it is possible to prevent the load of the electric actuator from becoming excessive, and
The interruption of the current can be reliably performed with a simple configuration.

It is preferable that a circuit for interrupting the supply of power to the electric actuator when the load current of the electric actuator exceeds a predetermined current value is provided independently of the control mechanism of the electric actuator. Thus, when the lock member prevents the rotation of the components of the planetary gear mechanism by the electric actuator to achieve the fail-safe function, it is possible to prevent the electric actuator from being overloaded.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. A rack and pinion type hydraulic power steering device 1 for a vehicle shown in FIG. 1 has a first input shaft 2 connected to a steering wheel (not shown), and is coaxially connected to the first input shaft 2 via a torsion bar 3. And a second input shaft 4. The torsion bar 3 is connected to the first input shaft 2 via a pin 5 and connected to the second input shaft 4 via a serration 6. Its first input shaft 2
Is supported by the housing 10 via the bearing 7, the second input shaft 4 is supported by the housing 10 via the bearing 8, and the first input shaft 4 is provided on the inner periphery of the concave portion 4 a formed at one end of the second input shaft 4. The outer circumference of one end of 2 is fitted via a bush 9. Thus, the input shafts 2 and 4 can be elastically rotated relative to each other in accordance with the steering torque. As shown in FIG.
The inner circumference of the recess 4a at one end of the second input shaft 4 and the first
The outer periphery of one end of the input shaft 2 is opposed to with a gap therebetween and is non-circular. This prevents excessive relative rotation of the input shafts 2 and 4 and prevents the torsion bar 3 from being damaged.

The second input shaft 4 is connected to the planetary gear mechanism 3
0 to the output shaft 11. The output shaft 11 is disposed coaxially with the second input shaft 4 with a gap therebetween, and is supported by the housing 10 via bearings 12 and 13. Its output shaft 1
The rotation of 1 is transmitted to the wheels by a rack and pinion type steering gear so that the steering angle changes. That is, a pinion 14 is formed integrally with the output shaft 11 so as to rotate together with the output shaft 11, and a rack 15 meshing with the pinion 14 is connected to wheels (not shown). Thereby, the rotation of the first input shaft 2 due to the steering is transmitted to the second input shaft 4 via the torsion bar 3, and the rotation of the second input shaft 4 in accordance with the steering is transmitted to the planetary gear mechanism 3.
The pinion 14 is rotated by being transmitted to the output shaft 11 via 0, and the rack 15 moves in the vehicle width direction.
This movement of the rack 15 changes the steering angle.

A hydraulic cylinder 20 is provided as a hydraulic actuator for generating a steering assist force. The hydraulic cylinder 20 includes a cylinder tube formed by the housing 10, a piston 21 formed integrally with the rack 15, and a pair of oil chambers 22 and 23 partitioned by the piston 21. The oil chambers 22 and 23 are connected to a pump 25 and a tank 26 via a rotary hydraulic control valve 24 built in the housing 10. The hydraulic control valve 24 controls the two oil chambers 22 according to the relative rotation amount of the first input shaft 2 and the second input shaft 4 according to the steering torque.
Pressure oil is supplied from one of pumps 23 to pump 23 and oil is returned to tank 26 from the other. Thereby, a steering assist force according to the steering resistance can be applied. The hydraulic control valve 24 may have a known configuration.

As shown in FIGS. 1 and 3, the planetary gear mechanism 30 holds a planetary gear 33 meshing with a sun gear 31 and a ring gear 32 by a carrier 34. The sun gear 31 is a first planetary gear element that is connected to the end of the second input shaft 4 so as to rotate with the sun gear 31. The carrier 34 is constituted by a pair of disk-shaped members 34 a and 34 b supporting both ends of the rotation shaft of the planetary gear 33, and is a second planetary gear element connected to the output shaft 11 so as to rotate together. The ring gear 32 is rotatably supported by the housing 10 via a bearing 35, and a worm wheel 32a is integrally formed on the outer periphery thereof. A worm 36 meshing with the worm wheel 32a is supported by the housing 10.
The worm 36 is driven by a motor (electric actuator) 38 attached to the housing 10. Thus, the ring gear 32 is a third planetary gear element that is driven to rotate by the motor 38.

As shown in FIG. 4, the motor 38 is connected to a control device 40 of the vehicle. The control device 40 has a vehicle speed sensor 41, a steering angle sensor 42 for detecting the rotation angle of the first input shaft 2, and an output. A rotation angle sensor 43 for detecting the rotation angle of the shaft 11 is connected. The control device 40
The rotation of the motor 38 according to the detection values from the sensors 41, 42, 43 so that the rotation transmission ratio of the planetary gear mechanism 30 from the second input shaft 4 to the output shaft 11 changes according to the vehicle speed. Control the speed. For example, in a stationary state where the vehicle speed is zero, the motor 38 is controlled so that the rotational angular velocity of the first input shaft 2 and the rotational angular velocity of the ring gear 32 become equal, and the rotational angular velocity of the ring gear 32 decreases as the rotational speed increases. Thereby, the turning performance at low speed and the running stability at high speed can be improved. The steering angle sensor 42
May detect the rotation angle of the second input shaft 4 instead of the rotation angle of the first input shaft 2.

As shown in FIG. 1, a lock member 45 is provided which is movable between a position where rotation of the ring gear 32 is permitted by the motor 38 and a position where rotation is prohibited. The lock member 45 of the present embodiment is movably inserted into the concave portion 10 a formed in the housing 10 along the radial direction of the ring gear 32. At the tip of the lock member 45, teeth 45a that can mesh with the worm wheel 32a on the outer periphery of the ring gear 32 are formed. This lock member 45
1 is in a state of being immersed in the concave portion 10a at the rotation allowable position, and is in a state of protruding from the concave portion 10a and meshing with the worm wheel 32a at the rotation preventing position as shown by a broken line in FIG. Accordingly, the lock member 45 prevents the rotation of the ring gear 32 by the motor 38 at the rotation prevention position.

The second input shaft 4 and the output shaft 1
A movement conversion mechanism 50 capable of converting the relative rotation of the first member into the movement of the lock member 45 is provided. 1 and 3
As shown in FIG. 5, the motion conversion mechanism 50 includes a pair of pressing portions 51 that rotate together with the second input shaft 4, a slider 52 that rotates together with the output shaft 11 and is movable in the axial direction, and a slider 52. A spring (elastic member) 53 for applying elastic force toward one side (upward in FIG. 1) in the axial direction. The two pressing portions 51 protrude outward from the outer periphery of the end of the second input shaft 4. The slider 52 has a disk-shaped portion 52a fitted to the output shaft 11 via a spline or serration so as to be movable in the axial direction and rotatable with the output shaft 11, and one side in the axial direction from one surface of the disk-shaped portion 52a. A pair of receiving portions 52b projecting upward (upward in FIG. 1), and the disc-shaped portion 5
2a, and a peripheral wall portion 52c standing upright from the outer peripheral edge portion 2a.
One disc-shaped member 34b of the carrier 34 is disposed between the disc-shaped portion 52a and the pressing portions 51. The spring 53 is constituted by a compression coil spring fitted on the outer periphery of the output shaft 11, and is arranged between the slider 52 and a spring receiver 54 fixed to the output shaft 11.

As shown in FIG. 3, each receiving portion 52b of the slider 52 is formed in an arc shape concentric with the output shaft 11, and penetrates an opening 34c formed in one disk-shaped member 34b of the carrier 34. In each pressing part 5
1 in the circumferential direction of rotation. Thereby, the pressing portion 51 and the receiving portion 52b of the slider 52 are
The input shaft 4 and the output shaft 11 are arranged at positions pressed against each other by relative rotation. As shown in FIG. 5A, the surface of each receiving portion 52b facing the pressing portion 51 is a guide surface 52b 'inclined with respect to the axial direction and the radial direction of the second input shaft 4. . When the pressing portion 51 and the slider 52 are pressed against each other via the guide surface 52b ', the slider 52 moves in the other axial direction (downward in FIG. 1) against the elasticity of the spring 53. In addition, instead of the guide surface 52b 'of the slider 52, or the guide surface 52b'
In addition, a guide surface may be provided on the pressing portion 51.

The slider 52 is moved in the other axial direction by the relative rotation of the second input shaft 4 and the output shaft 11 exceeding a predetermined set angle, so that the slider 52 shown in FIG.
From the restriction position shown in FIG. 5 to the restriction release position shown in (2) of FIG. The set angle may be determined in advance so that safe steering can be secured. As shown by the solid line in FIG. 1, the peripheral wall 52
c closes a part of the opening of the concave portion 10a, thereby holding the lock member 45 immersed in the concave portion 10a at the rotation allowable position and restricting the lock member 45 from moving to the rotation inhibition position. A compression coil spring (elastic member) for applying an elastic force toward the rotation preventing position to the lock member 45.
61 is provided in the concave portion 10a. In FIG. 1, 2
As shown by the dashed line, the slider 52 moved to the restriction release position does not close the opening of the recess 10a by the peripheral wall portion 52c. By the movement of the slider 52 to the restriction release position, the lock member 45 immersed in the concave portion 10a moves to the rotation preventing position by the elastic force of the spring 61. Accordingly, the lock member 45 is arranged at the rotation allowable position when the relative rotation angle between the second input shaft 4 and the output shaft 11 is equal to or less than the set angle, and is arranged at the rotation inhibition position when the relative angle exceeds the set angle. You.

An energization cutoff switch 71 connected to the control device 40 is disposed in the recess 10a.
The switch 71 operates in conjunction with the movement of the lock member 45 from the rotation allowable position to the rotation prevention position, and the control device 40 cuts off the power supply to the motor 38 by the operation.

According to the above configuration, when the relative rotation angle between the second input shaft 4 and the output shaft 11 exceeds the set angle due to the runaway of the motor 38 or the like, the relative rotation motion between the second input shaft 4 and the output shaft 11 is increased. The motion is converted by the motion converting mechanism 50 into the movement of the lock member 45. By this movement, the lock member 45 is displaced from the rotation allowing position of the ring gear 32 by the motor 38 to the rotation preventing position. Accordingly, the rotation of the second input shaft 4 is transmitted from the sun gear 31 to the output shaft 11 via the planetary gear 33 and the carrier 34.
Is transmitted to That is, by mechanically converting the excessive relative rotation of the input / output shafts 4 and 11 into movement of the lock member 45, the rotation of the ring gear 32 by the motor 38 is locked, and the second input shaft according to the driver's intention. 4
Can be transmitted to the output shaft 11, so that the fail-safe function can be reliably achieved.
Further, when the relative rotation angle between the second input shaft 4 and the output shaft 11 becomes excessive, the fail-safe function can be reliably achieved with a simple configuration. Further, by operating the switch 71 using the movement of the lock member 45 for achieving the fail-safe function, the power supply to the motor 38 can be cut off. Therefore, the lock member 4
5, when the rotation of the ring gear 32 by the motor 38 is prevented, the load on the motor 38 can be prevented from becoming excessive, and the energization can be reliably shut off with a simple configuration.

In place of the power cut-off switch 71 in the above-described embodiment, an electric circuit that cuts off power to the motor 38 when the load current of the motor 38 exceeds a predetermined current value is replaced with an electric circuit of the motor 38. It may be provided independently of the control mechanism. The electric circuit includes, for example, a load current detection circuit for the motor 38, an integration circuit for the detected load current value, a comparison circuit for comparing the output of the integration circuit with a preset value, and an integration circuit for the integration circuit. When the output of the motor exceeds the preset value, the output of the comparison circuit
And a logic circuit for turning off a relay switch provided in the middle of a current supply path to the power supply circuit 8. Accordingly, when the rotation of the ring gear 32 is prevented by the lock member 45 to achieve the fail-safe function, it is possible to prevent the load on the motor 38 from becoming excessive.

The present invention is not limited to the above embodiment. For example, the first planetary gear element connected to the input shaft is a ring gear or carrier, and the second planetary gear element connected to the output shaft is a sun gear or ring gear not connected to the input shaft, and is driven by an electric actuator. The third planetary gear element may be a sun gear or a carrier that is not connected to the input / output shaft. Also, the lock member may prevent the rotation of the components of the planetary gear mechanism by the electric actuator by directly connecting the two elements of the sun gear, the ring gear, and the carrier at the rotation prevention position. Further, the steering gear is not limited to the rack and pinion type, and may be, for example, a ball screw type. Further, the present invention can be applied to an electric power steering device that applies a steering assist force by an electric actuator.

[0023]

According to the present invention, in a steering device capable of changing the ratio of the steering angle to the steering amount according to the vehicle speed, the fail-safe function can be reliably achieved with a simple configuration.

[0024]

In the embodiment of the present invention, the lock member 45 prevents the motor 38 from rotating the components of the planetary gear mechanism 30 to provide a fail-safe function. 36
Locking the rotation of the motor can also provide a fail-safe function. For example, when the motor 38 is a three-phase brushless motor, a uniform current may flow through the three phases at the time of a failure, or the terminals of two phases among the three phases may be short-circuited to lock the rotation of the motor 38. Also, (1) in FIG.
(2) As shown in FIG.
Is fixed, the stopper 82 is fixed to the worm 36, and when the power is released during a failure, the telescopic member 81a of the solenoid actuator 81 is extended to contact the stopper 82, thereby rotating the worm 36. Can be locked. In this case, if the reduction ratio of the motor 38 by the worm 36 and the worm wheel 32a is 1 / n, the worm 36
By preventing the rotation of the ring gear 32, the torque acting on the stopper 82 becomes 1 / n compared to the case of preventing the rotation of the ring gear 32, so that a small stopper mechanism can be realized. Further, since the play of the steering wheel corresponding to one rotation of the worm 36 is 360 / n degrees, it is sufficient to provide only one stopper 82 on the circumference of the worm 36. In FIG. 6 (1) and (2), the same parts as those in the embodiment of the present invention are denoted by the same reference numerals.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a steering device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a fitting portion between a first input shaft and a second input shaft of the steering device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part of the steering device according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a control configuration of the steering device according to the embodiment of the present invention.

FIG. 5 is an explanatory view of a state of the slider in the steering device according to the embodiment of the present invention in a regulated position, and (2).
Shows the state at the restriction release position

FIGS. 6A and 6B are partial cross-sectional views of a steering device, respectively.

[Explanation of symbols]

 4 2nd input shaft 11 output shaft 30 planetary gear mechanism 31 sun gear 32 ring gear 33 planetary gear 34 carrier 38 motor 45 lock member 50 motion conversion mechanism 51 pressing part 52 slider 52b 'guide surface 53 spring 61 spring 71 switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takayoshi Takamatsu 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka Inside Koyo Seiko Co., Ltd. (72) Masaya Segawa 3--5 Minamisenba, Chuo-ku, Osaka-shi, Osaka No. 8 Inside Koyo Seiko Co., Ltd. (72) Ryohei Hayama 3-8-3 Minamisenba, Chuo-ku, Osaka City, Osaka Prefecture F-term inside Koyo Seiko Co., Ltd. 3D030 DC25 3D032 CC32 DA03 DA23 EB05 EC21 EC31 3D033 JB19

Claims (5)

[Claims] The rotation of an input shaft corresponding to steering is transmitted to an output shaft via a planetary gear mechanism, and the rotation of the output shaft is transmitted to wheels so that a steering angle is changed by a steering gear. In a steering device in which the rotation transmission ratio from the motor to the output shaft can be changed by rotating the components of the planetary gear mechanism in accordance with the vehicle speed with an electric actuator, the electric actuator allows rotation of the components of the planetary gear mechanism. A lock member movable between a position and an anti-rotation position, and a movement conversion mechanism capable of converting relative rotational movement of an input shaft and an output shaft thereof into movement of the lock member. When the relative rotation angle of the output shaft is equal to or less than a predetermined set angle, the output shaft is disposed at the rotation allowable position, and the set angle is set. Steering apparatus characterized by time exceeding are disposed in the rotation blocking position. 2. The planetary gear mechanism, wherein a planetary gear meshing with a sun gear and a ring gear is held by a carrier, and a first planetary gear element, which is one of the sun gear, the ring gear, and the carrier, is connected to the input shaft. And a second planetary gear element, which is not connected to the input shaft among the sun gear, the ring gear and the carrier, is connected to the output shaft and inputs and outputs between the sun gear, the ring gear and the carrier. A third planetary gear element not connected to the shaft is rotatably driven by the electric actuator, and the electric actuator is driven so that the rotation transmission ratio of the planetary gear mechanism from the input shaft to the output shaft changes according to the vehicle speed. And a lock mechanism for controlling the third planetary gear element in the rotation preventing position. Steering device according to claim 1 to prevent rotation. 3. A motion converting mechanism comprising: a pressing portion that rotates together with one of the two shafts; a slider that rotates together with the other of the two shafts and is movable in the axial direction; It has an elastic member that gives elasticity toward one side, and the pressing part and the slider are
The pressing portion and the slider are arranged in the axial direction and the radial direction of the input shaft so that the slider can be moved in the other axial direction against the elastic force by the pressing. The sliders are pressed against each other via guide surfaces that are inclined with respect to each other, and the sliders can be displaced from the restriction position to the restriction release position by movement in the other axial direction due to relative rotation of the two shafts exceeding the set angle, The lock member is provided with an elastic member that gives elasticity toward the rotation inhibition position, and the lock member is held at the rotation allowable position by a slider at the restriction position, and the elasticity due to the movement of the slider to the restriction release position is reduced. The steering device according to claim 1, wherein the steering device moves to the rotation preventing position by an action. 4. A switch according to claim 1, wherein a switch is provided that operates in conjunction with the movement of the lock member from the rotation permitting position to the rotation preventing position to cut off the power supply to the electric actuator. The steering device according to any one of the above. 5. The electric actuator according to claim 1, wherein a circuit for cutting off the current supply to the electric actuator when a load current of the electric actuator exceeds a predetermined current value is provided independently of a control mechanism of the electric actuator. The steering device according to any one of the above-described items.