JPH10100918A - Power steering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change a tire steering angle without changing a steering wheel angle by connecting planetary gears of input-output side gear mechanism with the same gear ratio to each other by a carrier, and controlling assist force in response to the rotation of the internal gear of the input side gear mechanism so as to fix or rotate the internal gear of the output side gear mechanism. SOLUTION: When a steering wheel H is steered, the rotation of an output shaft 3 is impeded by grounding resistance of tires (t), and input and output shafts 1 3 are relatively rotated so as to generate rotational difference between sun gears 9, 12 of input-output side gear machanisms A, B. Planetary gears 11, 14 are connected by a carrier 15, and the revolution of the planetary gear 11 is impeded by rotational difference. The planetary gear 11 is autorotated around the carrier 15 as an axis by that portion, and an internal gear 10 is rotated. A lever 16 therefore switches a spool 17 to impart assist force to steering of the tires (t). When a selector valve 28 is switched, a movable body 23 moves due to pressure difference, and the internal gear 13 is rotated by a specified angle by a lever 22. In response to this, autorotation of the planetary gear 11 is assisted and negated to change the turning angle of the internal gear 10, thus changing assist force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device capable of changing a turning angle of a tire without changing a steering wheel angle.

[0002]

2. Description of the Related Art In recent years, various functions of power steering devices have been required to be improved. As one of such methods, there is a demand for a tire capable of changing a turning angle of a tire without changing a steering wheel angle.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a power steering device capable of changing a turning angle of a tire without changing a steering wheel angle.

[0004]

A first aspect of the present invention relates to a power steering device, and an input shaft linked to a steering wheel.
An output shaft linked to the steering mechanism, a torsion bar connecting the input shaft and the output shaft, a sun gear provided on the input shaft, an internal gear provided rotatably coaxially with the sun gear,
And an input shaft side gear mechanism including a planetary gear interposed between the sun gear and the internal gear, a sun gear provided on the output shaft, an internal gear provided rotatably coaxially with the sun gear,
And an output shaft-side gear mechanism comprising a planetary gear interposed between the sun gear and the internal gear, and having the same gear ratio as the input shaft-side gear mechanism; A carrier that connects the planetary gears with the shaft-side gear mechanism while supporting them rotatably, an assist force control mechanism that controls the assist force according to the rotation of the internal gear of the input shaft-side gear mechanism, and an output shaft side It is characterized in that it has a drive mechanism for keeping the internal gear of the gear mechanism fixed or rotating it.

A second aspect of the present invention relates to a power steering apparatus, and relates to an input shaft linked to a steering wheel, an output shaft linked to a steering mechanism, a torsion bar connecting the input shaft and the output shaft, an input shaft and an output. A sun gear disposed between the shaft and an internal gear rotatably provided coaxially with the sun gear;
And an input shaft side gear mechanism comprising a planetary gear interposed between the sun gear and the internal gear, an internal gear rotatably provided coaxially with the sun gear, and an intermediary between the sun gear and the internal gear An output shaft-side gear mechanism, which is made of a planetary gear set having the same gear ratio as the input shaft-side gear mechanism, and a planetary gear of the input shaft-side gear mechanism and the output shaft-side gear mechanism, which are rotatable. A carrier that is connected to the input shaft and the output shaft while supporting it, an assist force control mechanism that controls the assist force according to the rotation of the internal gear of the input shaft side gear mechanism, and an internal gear of the output shaft side gear mechanism. It is characterized in that it has a drive mechanism for keeping it fixed or rotating it.

[0006] A third invention is the first and second inventions,
The drive mechanism is a lever provided on the outer peripheral surface of the internal gear of the output shaft side gear mechanism, a movable body that moves the lever to rotate the internal gear, and a pair of pressure chambers facing both ends of the movable body, With a spring that keeps the movable body in the normal state,
The pressure chamber is connected to the hydraulic pressure source and the tank via the switching valve, and the controller switches the switching valve according to the running state of the vehicle, closes both pressure chambers, or connects one of the pressure chambers to the hydraulic pressure source And the other pressure chamber is configured to communicate with the tank.

[0007] A fourth invention is the first and second inventions,
The drive mechanism includes a lever provided on the outer peripheral surface of the internal gear of the output shaft side gear mechanism, a movable body that moves the lever to rotate the internal gear, and a motor that links the output shaft to the movable body via a ball screw mechanism. The controller is characterized in that the controller controls the motor in accordance with the running state of the vehicle to keep the movable body in a normal state or to move the movable body.

[0008] A fifth invention is the first or second invention, wherein:
The drive mechanism is a lever provided on the outer peripheral surface of the internal gear of the output shaft side gear mechanism, a movable body that moves the lever to rotate the internal gear, and a pair of pressure chambers facing both ends of the movable body, With a spring that keeps the movable body in the normal state,
A pump mechanism is provided that connects the two pressure chambers via a throttle and that is linked to the input shaft. The pump mechanism sucks hydraulic oil from one of the pressure chambers according to the rotation direction and speed of the input shaft. It is characterized in that it is configured to discharge it to the other pressure chamber.

[0009]

1 and 2 show a power steering apparatus according to a first embodiment. An input shaft 1 linked to a handle H and an output shaft 3 provided with a pinion 2 are connected via a torsion bar 4. The pinion 2 provided on the output shaft 3 is engaged with a rack 6 formed on the steering rod 5. Further, a piston 7 is provided on the steering rod 5 to which the tire t is linked at both ends, and the piston 7 is slidably incorporated in the cylinder tube 8. In addition,
It is assumed that the steering rod 5, the pinion 2, the rack 6 and the like constitute a steering mechanism of the present invention.

At the lower end of the input shaft 1, a sun gear 9 is formed integrally. The internal gear 10 is arranged coaxially with the sun gear 9, and a plurality of planetary gears 11 are interposed between the sun gear 9 and the internal gear 10.
The sun gear 9, the internal gear 10, and the planetary gear 1
1 together form the input shaft side gear mechanism A.

A sun gear 12 is provided at the upper end of the output shaft 3.
Are integrally formed. An internal gear 13 is arranged coaxially with the sun gear 12, and the same number of planetary gears 14 as the planetary gears 11 are interposed between the sun gear 12 and the internal gear 13. However, the planetary gear 14
The planetary gears 11 and 14 are connected to each other by a carrier 15, and the planetary gears 11 and 14 are rotatable with respect to the carrier 15. It is assumed that the sun gear 12, the internal gear 13, and the planetary gear 14 together constitute an output shaft side gear mechanism B. The output shaft side gear mechanism B has the same gear ratio as the input shaft side gear mechanism A.

The internal gear 10 on the input shaft side gear mechanism A side
Are rotatably supported. And this internal gear 1
A lever 16 is provided on the outer peripheral surface of the
7 is fitted in a hole 18 formed at the end. The spool 17 is slidably incorporated in a spool hole 19 extending in a tangential direction of the internal gear 10. Therefore, when the internal gear 10 rotates, the lever 16
Pushes the side wall of the hole 18 to move the spool 17.

When the spool 17 is at the neutral position shown in FIG. 2, the two cylinder ports 19a and 19b communicate with the pump port 20 and the tank port 21. Therefore, the cylinder chambers 8a and 8b in the cylinder tube 8 connected to the cylinder ports 19a and 19b are
Will be in communication. When the spool 17 is switched in either direction, only one of the cylinder ports 19a or 19b communicates with the pump port 20 and the other cylinder port 19b or 19a.
Only the tank communicates with the tank port 21. Therefore, a differential pressure is generated in the cylinder chambers 8a and 8b in the cylinder tube 8, and the piston 7 is moved to apply an assist force to the steering of the tire t. It is assumed that the lever 16, the spool 17, the piston 7, the cylinder tube 8, and the like together constitute an assist force control mechanism of the present invention.

The internal gear 13 on the output shaft side gear mechanism B side is also rotatably supported. A lever 22 is provided on the outer peripheral surface of the internal gear 13 at a position substantially 180 degrees shifted from the lever 16 with respect to the axis of the torsion bar 4, and its tip is fitted into a hole 24 formed in a movable body 23. In. The movable body 23 is slidably incorporated in a movable body hole 25 extending in a tangential direction of the internal gear 13. The pressure chambers 26a and 26b formed by the movable body hole 25 and the movable body 23 have springs 27a and 2b.
7b is provided, and the movable body 23 is maintained in a normal state shown in FIG. 2 by its elastic force.

The pressure chambers 26a and 26b are provided with the switching valve 2
8 is connected to the hydraulic pressure source 29 and the tank T. If the switching valve 28 is in the neutral position shown in FIG.
Both pressure chambers 26a and 26b are closed. On the other hand, when one of the solenoids 30a or 30b is excited by a command from the controller C, the switching valve 2
8 is switched so that one of the pressure chambers 26a or 26b communicates with the hydraulic pressure source 29 and the other pressure chamber 26a or 26b
b or 26a communicates with the tank T. Therefore, a differential pressure is generated in these pressure chambers 26a, 26b, and the movable body 23 moves against the spring 27b or 27a.

It is assumed that the lever 22, the movable body 23, the pressure chambers 26a and 26b, the springs 27a and 27b, the switching valve 28, the controller C and the like constitute a drive mechanism of the present invention. The controller C is connected to a sensor 31 for detecting a vehicle state and a course condition. As the sensor 31, a yaw rate sensor, a lateral acceleration sensor, a vehicle speed sensor, a steering wheel angle sensor, or the like may be selected according to the purpose and used in combination. Further, a stroke sensor 32 for detecting the stroke of the movable body 23 is provided, and the detection result is fed back to the controller C.

Next, the operation of the power steering device will be described. During normal traveling, the controller C keeps the switching valve 28 at the neutral position shown in FIG. At this time,
As described above, since both the pressure chambers 26a and 26b are closed, the movable body 23 is in a fixed state. When the steering wheel H is turned in this state, the steering torque is transmitted to the input shaft 1. However, the rotation of the output shaft 3 linked to the steering rod 5 is hindered by the ground resistance on the tire t side or the like. Are twisted, and the input shaft 1 and the output shaft 3 rotate relative to each other. Therefore, a rotation difference occurs between the sun gear 9 of the input shaft side gear mechanism A and the sun gear 12 of the output shaft side gear mechanism B.

At this time, the planetary gear 11 tends to revolve more than the planetary gear 14 due to the rotation difference. However, these planetary gears 11 and 14 are
, The planetary gear 11 is prevented from revolving, and only rotates by the carrier 15 as an axis. The rotation of the planetary gear 11 causes the internal gear 10 to rotate. Thus, the input shaft 1 and the output shaft 3
The internal gear 10 rotates in accordance with the relative rotation amount with respect to. When the internal gear 10 rotates, the lever 16 switches the spool 17, and as described above, a pressure difference is generated between the cylinder chambers 8a and 8b, and an assist force is applied to the steering of the tire t. You.

It is assumed that the controller C excites the solenoid 30a or 30b and switches the switching valve 28 with the handle H turned off. When the switching valve 28 is switched, as described above, a differential pressure is generated in the pressure chambers 26a and 26b, so that the movable body 23 moves and rotates the internal gear 13 through the lever 22 by a predetermined angle. At this time, according to the rotation angle of the internal gear 13, the planetary gear 14 meshing with the sun gear 12, which hardly rotates, revolves while rotating. Therefore, the planetary gear 11 connected to the planetary gear 14 via the carrier 15 also attempts to revolve while rotating, so that the rotation of the planetary gear 11 by turning the handle is assisted or canceled. As a result, the same effect as when the handle H is increased or returned is obtained. In this way, by assisting or canceling the rotation of the planetary gear 11 in accordance with the rotation of the internal gear 13, the rotation angle of the internal gear 10 can be changed, and the assist force can be increased,
Or make it smaller.

According to the power steering apparatus of the first embodiment described above, when the steering wheel H is turned, an appropriate assisting force can be obtained. Moreover, if the controller C controls the switching valve 28 to move the movable body 23, the assist force can be increased or decreased. Therefore, the turning angle of the tire t can be changed without changing the steering wheel angle. As described above, if it is possible to change the turning angle of the tire t without changing the steering wheel angle, for example, when the driver makes a mistake in the steering wheel operation, the sensor 31 detects it and corrects the mistake. Becomes possible. In addition, it is possible to improve the operability by increasing the turning angle of the tire t during so-called stationary turning, and to reduce the turning angle of the tire t to ensure stability during high-speed running of the vehicle.

In the second embodiment shown in FIG. 3, a stepping motor 33 is used as a driving mechanism instead of a hydraulic pressure. The rest of the configuration is exactly the same as in the first embodiment, and a detailed description thereof will be omitted. A stroke hole 35 for allowing a stroke of an output shaft 34 described later is formed in the axial direction of the movable body 23. A screw member 36 having a screw hole is attached to an end of the movable body 23. Stepping motor 33
Is inserted into the screw hole of the screw member 36. A screw groove is formed on the output shaft 34, and a plurality of balls 37 are interposed between the screw groove and the screw hole.

In the power steering apparatus of the second embodiment described above, an appropriate assist force can be obtained by turning the steering wheel H. Moreover, if the controller C controls the stepping motor 33 to move the movable body 23, the assist force can be increased or decreased. Therefore, the turning angle of the tire t can be changed without changing the steering wheel angle.

In the third embodiment shown in FIGS. 4 and 5, the use of hydraulic pressure as the driving mechanism is the same as in the first embodiment, but the pressure guided to the pressure chambers 26a and 26b is linked to the input shaft 1. It is controlled by a pump mechanism. The rest of the configuration is exactly the same as in the first embodiment, and a detailed description thereof will be omitted. A drive gear 38a of a gear pump 38 constituting a pump mechanism is linked to the input shaft 1. In the gear pump 38, the drive gear 38a rotates while meshing with the driven gear 38b according to the direction in which the handle H is turned, and discharges hydraulic oil in either direction. Port 39 of this gear pump
a to the pressure chamber 26a, and the port 39b to the pressure chamber 26a.
b. And these pressure chambers 2
6 a and 26 b communicate with each other via a diaphragm 40.

Next, the operation of the power steering device will be described. When the handle H is at the neutral position, the two pressure chambers 26a and 26b communicate with each other through the throttle 40, and the movable body 23 maintains the normal state shown in FIG. 4 by the springs 27a and 27b. Now, handle H
And the gear pump 38 is rotated in the direction of the arrow in FIG. For example, when the vehicle is running at high speed, the steering wheel H is slowly turned, so that the flow rate discharged from the gear pump 38 is small. Therefore, the hydraulic oil discharged from the gear pump 38 leaks from the throttle 40, and the two pressure chambers 26a,
The pressure difference is hardly generated at 26b, and the movable body 23 keeps a substantially normal state. At this time, as described above, the input shaft side gear mechanism A and the output shaft side gear mechanism B
Through the above, an assist force corresponding to the relative rotation amount between the input shaft 1 and the output shaft 3 is applied.

On the other hand, when the steering wheel H is quickly turned off as shown in FIG. 5A when traveling on a mountain road or when avoiding danger, the flow rate discharged from the gear pump 38 increases accordingly. Accordingly, the hydraulic oil discharged from the gear pump 38 is guided to the pressure chambers 26b, and these pressure chambers 26a, 26
A differential pressure is generated in b, and the movable body 23 is moved. In this case, not only is the assist force according to the relative rotation amount between the input shaft 1 and the output shaft 3 applied, but also the movable body 23
, That is, the rotation of the internal gear 13, the tire t
, The response of the vehicle can be improved (see the x-ray in FIG. 5B). And handle H
When the pressure is stopped, since the pressure chambers 26a and 26b communicate with each other via the throttle 40, the turning angle of the tire returns to the same as the turning angle of the tire in the normal state shown by the y line in FIG. Therefore, the stability of the vehicle is improved.

In the power steering apparatus of the third embodiment described above, an appropriate assist force can be obtained by turning the steering wheel H. When the steering wheel H is quickly turned, such as when driving on a mountain road or when avoiding danger, the assisting force at that time can be increased, and the turning angle of the tire t can be changed without changing the steering wheel angle. In addition, since a so-called differential operation of discharging hydraulic oil in proportion to the rotation speed of the handle H is performed, a response to the movement of the handle H can be improved, and stable control can be performed.

The fourth embodiment shown in FIG. 6 is different from the first to third embodiments in that the configurations of the input shaft side gear mechanism A and the output shaft side gear mechanism B are changed. Therefore, the following description focuses on the differences, and a detailed description of other configurations is omitted. As shown in FIG. 6, a flange portion 41 is formed at the lower end of the input shaft 1. A flange 42 is formed at the upper end of the output shaft 3. The flanges 41 and 42 are opposed to each other, and a rotatable sun gear 43 is disposed between the flanges 41 and 42. The input shaft 1 is coaxial with the sun gear 43.
The internal gear 44 is provided on the output shaft 3 side, and the internal gear 45 is provided on the output shaft 3 side.
Has been arranged. The lever 1 provided on the internal gear 44
6 is linked to the spool 17, and the lever 22 provided on the internal gear 45 is linked to the movable body 23.
This is exactly the same as the third embodiment.

The internal gears 44 and 45 and the sun gear 43
, A plurality of planetary gears 46 and 47 are interposed. The planetary gear 46 on the input shaft 1 side is connected to the flange 41 by a carrier 48, and the planetary gear 46 is rotatable relative to the carrier 48. Similarly, the planetary gear 47 on the output shaft 3 side
Also, the carrier 49 is connected to the flange portion 42, and the planetary gear 47 is rotatable relative to the carrier 49. In addition, the sun gear 43 is shared, and the internal gear 44 and the planetary gear 46 together constitute an input shaft side gear mechanism A, and the internal gear 45 and the planetary gear 47 together constitute an output shaft side gear mechanism B. And These input / output shaft side gear mechanisms A and B have the same gear ratio.

Next, the operation of the power steering device will be described. During normal running, as described in the first to third embodiments, the movable body 23 is in a fixed state. When the steering wheel H is turned in this state and the steering torque is transmitted to the input shaft 1, the torsion bar 4 is twisted, and the input shaft 1 and the output shaft 3 rotate relatively. At this time, the sun gear 43
Meshes with the planetary gear 47 on the output shaft 3 side which hardly rotates, so that its rotation is hindered. Therefore, the planetary gear 46 on the input shaft 1 side that meshes with the sun gear 43 is
While rotating the internal gear 44, it rotates while revolving around the sun gear 43. As described above, the internal gear 44 rotates according to the relative rotation amount between the input shaft 1 and the output shaft 3. Then, when the internal gear 44 rotates, the lever 16 switches the spool 17, and as described above, a pressure difference occurs between the cylinder chambers 8a and 8b.
An assist force is applied to the turning of the tire t.

If the movable body 23 is moved with the handle H turned off, the internal gear 45 rotates through the lever 22 by a predetermined angle. At this time, the sun gear 43 rotates via the planetary gear 47 according to the rotation angle of the internal gear 45. Then, when the sun gear 43 rotates, the planetary gear 46 assists in rotation while revolving,
Or cancel. As described above, if the rotation of the planetary gear 46 is assisted or canceled in accordance with the rotation of the internal gear 45, the rotation angle of the internal gear 44 can be changed. Therefore, the assist force can be increased or decreased, and the turning angle of the tire t can be changed without changing the steering wheel angle.

[0031]

According to the first and second aspects of the present invention, an appropriate assist force can be obtained by turning the steering wheel. Moreover,
If the internal gear of the output shaft side gear mechanism is rotated by the drive mechanism, the assist force can be increased or decreased. Therefore, the turning angle of the tire can be changed without changing the steering wheel angle. In the third invention, in the first and second inventions, since hydraulic pressure is used, the drive mechanism can be configured relatively easily and at no cost.

According to a fourth aspect, in the first and second aspects,
Since the motor is used and the output is transmitted to the movable body via the ball screw mechanism, the movement of the movable body can be smoothed, and more smooth control can be performed. Fifth
In the first invention, the pump mechanism is linked to the input shaft in the first and second inventions, and the movable body is moved in accordance with the rotation direction and speed of the handle, so that a controller is not required and further cost reduction is possible. Becomes Further, since a so-called differential operation is performed, the response to the movement of the steering wheel can be improved, and stable control can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a power steering device according to a first embodiment.

FIG. 2 is a partial cross-sectional view as seen from the direction of arrow II in FIG.

FIG. 3 is a partial cross-sectional view of a power steering device according to a second embodiment.

FIG. 4 is a partial cross-sectional view of a power steering device according to a third embodiment.

FIG. 5 (a) shows the relationship between the time and the steering wheel angle in the power steering apparatus according to the third embodiment, and FIG. 5 (b)
Shows the relationship between the time and the turning angle of the tire.

FIG. 6 is a sectional view of a power steering device according to a fourth embodiment.

[Explanation of symbols]

 1 input shaft 2 pinion 3 output shaft 4 torsion bar 5 steering rod 6 rack 9,12,43 sun gear 10,13,44,45 internal gear 11,14,46,47 planetary gear 15,48,49 carrier 16,22 Lever 17 Spool 23 Movable body 26a, 26b Pressure chamber 27a, 27b Spring chamber 28 Switching valve 33 Stepping motor 37 Ball 38 Gear pump 40 Throttle

Claims (5)

[Claims] An input shaft linked to a steering wheel, an output shaft linked to a steering mechanism, a torsion bar connecting the input shaft and the output shaft, a sun gear provided on the input shaft, and a coaxial line with the sun gear. The internal gear provided rotatably on the input shaft side gear mechanism consisting of an internal gear and a planetary gear interposed between the sun gear and the internal gear, the sun gear provided on the output shaft, and rotating coaxially with the sun gear An internal gear freely provided, and an output shaft side gear mechanism comprising a planetary gear interposed between the sun gear and the internal gear, and having the same gear ratio as the input shaft side gear mechanism; A carrier that connects the planetary gears of the input shaft side gear mechanism and the output shaft side gear mechanism while supporting them rotatably, and an assist force that controls the assist force according to the rotation of the internal gear of the input shaft side gear mechanism. Control mechanism and output shaft side teeth A power steering device comprising: a drive mechanism for keeping an internal gear of a vehicle mechanism fixed or rotating the internal gear. 2. An input shaft linked to a steering wheel, an output shaft linked to a steering mechanism, a torsion bar connecting the input shaft and the output shaft, and a sun gear disposed between the input shaft and the output shaft. An internal gear rotatably provided coaxially with the sun gear, and an input shaft side gear mechanism comprising a planetary gear interposed between the sun gear and the internal gear, and a rotatable coaxially with the sun gear. An output gear-side gear mechanism comprising an internal gear provided, a planetary gear interposed between the sun gear and the internal gear, and having the same gear ratio as the input shaft-side gear mechanism; A carrier that connects the planetary gears of the gear mechanism and the output shaft side gear mechanism to the input shaft and output shaft while supporting it rotatably, and controls the assist force according to the rotation of the internal gear of the input shaft side gear mechanism. Assist force control mechanism and output shaft side gear machine A power steering device, comprising: a drive mechanism for keeping or rotating an internal gear of a structure. 3. A drive mechanism comprising: a lever provided on the outer peripheral surface of an internal gear of the output shaft side gear mechanism; a movable body for moving the lever to rotate the internal gear; and a pair of movable bodies facing both ends of the movable body. A pressure chamber, and a spring for keeping the movable body in a normal state.The pressure chamber is connected to a hydraulic pressure source and a tank via a switching valve, and the controller switches the switching valve according to the traveling state of the vehicle. The power steering apparatus according to claim 1 or 2, wherein the pressure chamber is closed, one of the pressure chambers is connected to a hydraulic pressure source, and the other pressure chamber is connected to a tank. . 4. A drive mechanism comprising: a lever provided on the outer peripheral surface of an internal gear of the output shaft side gear mechanism; a movable body for moving the lever to rotate the internal gear; and a movable body for moving the output shaft via a ball screw mechanism. A motor coupled to the vehicle, wherein the controller controls the motor in accordance with the running state of the vehicle, and keeps the movable body in a normal state or moves the movable body. 3. The power steering device according to 1 or 2. 5. A drive mechanism comprising: a lever provided on the outer peripheral surface of an internal gear of the output shaft side gear mechanism; a movable body that operates the lever to rotate the internal gear; and a pair of movable bodies facing both ends of the movable body. A pressure chamber, and a spring that keeps the movable body in a normal state.The two pressure chambers communicate with each other via a throttle, and a pump mechanism linked to the input shaft is provided. 3. The power steering device according to claim 1, wherein the hydraulic oil is sucked from one of the pressure chambers and discharged to the other pressure chamber according to the speed.