JP3132947B2 - Power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rack-and-pinion type power steering device for assisting a steering force.

2. Description of the Related Art As this type of device, for example,
What is described in No. 30217 is conventionally known. In this conventional device, a pinion linked to a handle and a pinion linked to an electric motor are engaged with a rack formed on a rack shaft. Then, when the controller outputs a signal corresponding to the rotational torque of the steering wheel, the electric motor is driven to power assist the steering force.

[0002]

The conventional apparatus as described above requires two pinions, a pinion linked to the steering wheel and a pinion linked to the electric motor. In order to require two pinions in this way, two linking mechanisms are required, and the configuration becomes more complicated,
It was difficult to secure space in a small engine room. In addition, since the output of the electric motor was controlled by a complicated controller, there was concern about electrical failure and the cost was high. Therefore, an object of the present invention is to provide a device which can be mounted with a single pinion and which has a simple structure, thereby improving the mountability and having less fear of failure at a low cost.

[0003]

According to the present invention, a stub shaft and a pinion shaft are connected via a torsion bar, and the stub shaft is linked to a handlebar.
It is assumed that the pinion shaft is a power steering device in which a pinion that meshes with a rack formed on a rack shaft is formed. The first invention connects the stub shaft and the pinion shaft via a torsion bar, and connects the stub shaft to the handle, and engages the pinion shaft with a rack formed on a rack shaft while assuming the above device. In a power steering device formed with a pinion, one drive bevel gear, a pair of driven bevel gears that mesh with the drive bevel gear with their axes shifted by 90 degrees, and that oppose each other, and drive this drive bevel gear And a drive mechanism, the stub shaft and the pinion shaft, respectively, protrude between the opposing portions of the pair of driven gears, for both these driven gears, the stub shaft and the pinion shaft are rotatable, Moreover, between the pair of driven gears, the stub shaft and the pinion shaft A movable body is provided, which is spline-coupled to a stub shaft, helical gear-coupled to a pinion shaft, and a first clutch is provided between the movable body and one of the driven gears. A mechanism is provided, and a second clutch mechanism is provided between the movable body and the other driven bevel gear. A second invention is characterized in that a movable body straddling a stub shaft and a pinion shaft is helically spline-coupled to the stub shaft and straight spline-coupled to the pinion shaft. According to a third invention, a steering torque sensor is provided on both sides of a projection provided on a movable body in the first and second inventions, and drive control of a drive bevel gear is performed in accordance with an output signal of the torque sensor. It is a feature.

[0004]

According to the first or second aspect of the present invention, when the stub shaft is rotated, the torsion bar is twisted according to the input torque. However, the pinion shaft is stub shaft and pinion shaft Rotate relative to each other while twisting the torsion bar. When the stub shaft and the pinion shaft rotate relative to each other, the movable body moves in accordance with the direction of rotation. That is, when the stub shaft rotates, the movable body that is straight or helically splined with the stub shaft also rotates integrally. However, since the movable body is also connected to the pinion shaft by a helical or straight spline, when the movable body rotates as described above, the movable body moves in the axial direction according to the rotation direction.

[0005] When the movable body moves as described above, the clutch mechanism provided in the moving direction is connected.
It is rotated by the driving force of the driving bevel gear. When the movable body rotates, the stub shaft and the pinion shaft rotate integrally via the movable body. Further, according to the third aspect, when the movable body moves in the axial direction, the protrusion of the movable body turns on one of the steering torque sensors. Only in this case, the power of the drive mechanism is transmitted by the output of the steering torque sensor to perform the steering assist operation. On the other hand, when torque greater than the set value is not input to the torsion bar, the movement of the movable body in the axial direction is very small. Be cut.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment shown in FIGS.
The stub shaft 5 is connected to the pinion 6 via the movable body case 3, and the pinion 6 is connected to the rack 18.
I'm engaged. FIG. 2 shows the configuration inside the movable case 3. The stub shaft 5 and the pinion shaft 1
9 is connected via a torsion bar 7 so that the shafts 5 and 19 can rotate relative to each other while twisting the torsion bar 7. The stub shaft 5 and the pinion shaft 19 are respectively provided with driven driven gears 8 and 9 so as to be rotatable, and the pair of driven driven gears 8 and 9 are provided with a drive shifted by 90 degrees with respect to the axis thereof. The bevel gear 4 is engaged.

Therefore, when the driving bevel gear 4 rotates, the driven bevel gears 8 and 9 rotate in directions opposite to each other. The drive bevel gear 4 is linked to the drive mechanism 1 via the flexible shaft 2. here,
The drive mechanism 1 includes an electric motor m that rotates in one direction and a speed reducer 20, and an output shaft of the speed reducer 20 is linked to the drive bevel gear 4. The pair of driven bevel gears 8, 9
In between, the stub shaft 5 and the pinion shaft 19
And a tubular select gear 10 as a movable body is fitted so as to straddle both.

The select gear 10 is provided with a projection 15 which is formed on the circumference at the center, and a steering torque sensor 16 is arranged on both sides of the projection 15 in the axial direction. The select gear case 3 includes:
A torque judging device 17 for outputting an output for driving the electric motor m based on a signal of the steering torque sensor 16 is provided. This select gear 10 is connected to the stub shaft 5 by straight spline connection and to the pinion shaft 19 by helical spline connection.
Of course, the stub shaft 5 may be connected by helical spline connection, and the pinion shaft 19 may be connected by straight spline connection. That is, the tip portion of the stub shaft 5 is used as a spline shaft 11, and the spline shaft 11 is provided with the select gear 1.
The straight spline portion 12 formed on one side of the "0" is engaged. Helical spline portions 21 and 22 are formed on the pinion shaft 19 side and the other side of the select gear 10, and these two gear portions 21 and 22 are engaged with each other.

A first clutch mechanism 13 is provided on the select gear 10 and one driven gear 8 as described above, and a second clutch mechanism 14 is provided between the select gear 10 and the other driven gear 9. . In this embodiment, gears 13a and 13b are used as the first clutch mechanism 13, and gears 14a and 14b are used as the second clutch mechanism 14. Next, the operation of the first embodiment will be described. Now, when the stub shaft 5 is rotated by turning the handle H, the rotational force is transmitted to the pinion shaft 19 via the torsion bar 7. However, at this time, the pinion shaft 1
The stub shaft 5 rotates relative to the pinion shaft 19 while twisting the torsion bar 7 because the 9 acts in a direction that does not rotate due to the resistance on the tire side.

When the stub shaft 5 rotates in this way, the select gear 10 also rotates integrally therewith. However, since the pinion shaft 19 operates in the direction in which the pinion shaft 19 does not rotate as described above,
Move in the axial direction according to the leads of the helical spline portions 21 and 22. However, the moving direction of the select gear 10 differs depending on the rotating direction of the stub shaft 5.
For example, when the stub shaft 5 is rotated to the left, the select gear 10 moves to the upper side in the drawing, and the first clutch mechanism 1
3 and the torque sensor 1 above the projection 15
Turn on 6. Then, only when a torque equal to or greater than a certain set value is input, the driving force of the electric motor m is output by the output of the torque determination device 17.

On the other hand, when the stub shaft 5 rotates to the right, contrary to the above, the select gear 10 moves to the lower side in the drawing, connects the second clutch mechanism 14, and turns on the lower torque sensor 16. Then, when a torque equal to or greater than the set value is input, the driving force of the electric motor m is output. Therefore, when the first clutch mechanism 13 is connected, the driving bevel gear 4 linked to the electric motor m is turned to the arrow 23.
If it is rotating in the direction, the select gear 10 rotates to the left along with the driven bevel gear 8. When the select gear 10 rotates to the left while the first clutch mechanism 13 is connected as described above, the stub shaft 5 and the pinion shaft 19 are rotated.
Are rotated integrally to the left via the select gear 10. That is, the pinion shaft 19 is rotated by the driving force of the electric motor m to move the rack 18, and power assist the steering force.

Conversely, when the second clutch mechanism 14 is connected, the select gear 10 rotates rightward with the driven bevel gear 8. Thus the second
With the clutch mechanism 14 connected, the select gear 10
Is rotated right, the stub shaft 5 and the pinion shaft 19 are integrally rotated right via the select gear 10. Also in this case, the pinion shaft 19 is rotated by the driving force of the electric motor m to move the rack 18,
This is to power assist the steering force. In the second embodiment shown in FIGS. 3 and 4, instead of the gears 13 a, 13 b, 14 a, and 14 b,
The configuration and operation are the same as those of the first embodiment except that the friction plates 103a, 103b, 104a, and 104b are used, and the clutch member 24 is provided between the drive mechanism 1 and the movable body case 3. That is, the clutch member 24 is turned on only when torque equal to or greater than the set value is input to the torque determination device 17 so that the driving force of the electric motor m is transmitted to the driving bevel gear 4. In this embodiment, the select gear 1
After the protrusion of No. 0 turns on the steering torque sensor, friction slope 1
03a, 103b, 104a, and 104b are set so as to be connected, so that a sudden change in the steering force during output transmission can be prevented.

Here, the select gear 10 moves in the axial direction in proportion to the degree of torsion of the torsion bar 7, that is, the input torque to the stub shaft 5, and the friction plate 103
The pressing force of the a and 104a against the friction plates 103b and 104b also changes linearly. By using a friction clutch whose friction coefficient is constant without being affected by an external force, the transmission torque changes linearly in proportion to the pressing force. That is, the steering assist force from the electric motor m changes linearly in proportion to the input torque of the stub shaft 5. In the present embodiment, the drive mechanism 1 is mainly composed of an electric motor and a speed reducer that rotate in one direction at a fixed speed. However, if an engine is used instead,
Since there is no need for a separate motor for power assist,
Further, the installation space can be reduced.

[0014]

According to the power steering apparatus of the first and second aspects of the present invention, both the stub shaft and the pinion shaft can be rotated by the driving force of the driving mechanism as described above. One is sufficient, the configuration is simplified, and the mountability is improved. Also,
Since a complicated controller is not used, a device with less fear of failure can be realized at low cost. According to the third aspect, in addition to the above items, the power assist can be performed by the steering torque.

[Brief description of the drawings]

FIG. 1 is a mechanism diagram of a first embodiment.

FIG. 2 is an enlarged sectional view of a main part of the first embodiment.

FIG. 3 is a mechanism diagram of a second embodiment.

FIG. 4 is an enlarged sectional view of a main part of a second embodiment.

[Sign]

 H Handle 1 Drive mechanism 2 Flexible shaft 4 Drive bevel gear 5 Stub shaft 6 Pinion 7 Torsion bar 8 Follower bevel gear 9 # 10 Select gear 11 Spline shaft section 12 Straight spline section 13 First clutch mechanism 14 Second clutch mechanism 15 Projection 16 Torque sensor 18 Rack 19 Pinion shaft

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-220968 (JP, A) JP-A-54-102727 (JP, A) JP-A 61-109868 (JP, U) JP-A 59-102868 53175 (JP, U) Jiko 3-30217 (JP, Y2) (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 5/04

Claims (3)

(57) [Claims] 1. A power steering apparatus comprising: a stub shaft and a pinion shaft connected to each other via a torsion bar; a stub shaft connected to a handle; and a pinion formed on the pinion shaft to engage with a rack formed on a rack shaft. In the above, while one drive bevel gear, this drive bevel gear includes a pair of driven bevel gears that mesh with the direction of the axis shifted by 90 degrees and face each other, and a drive mechanism that drives this drive bevel gear, Each of the stub shaft and the pinion shaft is projected between the opposing portions of the pair of driven gears, and the stub shaft and the pinion shaft are made rotatable with respect to the two driven gears. When a movable body that straddles a stub shaft and a pinion shaft is provided, In both cases, the movable body is straight spline-coupled to the stub shaft, helical spline-coupled to the pinion shaft, and a first clutch mechanism is provided between the movable body and one of the driven gears. And a second clutch mechanism provided between the second driven gear and the other driven gear. 2. A power steering apparatus comprising: a stub shaft and a pinion shaft connected to each other via a torsion bar; a stub shaft linked to a handle; and a pinion formed on the pinion shaft to engage with a rack formed on a rack shaft. In the above, while one drive bevel gear, this drive bevel gear includes a pair of driven bevel gears that mesh with the direction of the axis shifted by 90 degrees and face each other, and a drive mechanism that drives this drive bevel gear, Each of the stub shaft and the pinion shaft is projected between the opposing portions of the pair of driven gears, and the stub shaft and the pinion shaft are made rotatable with respect to the two driven gears. When a movable body is provided over the stub shaft and the pinion shaft, In addition, the movable body is helically spline-coupled to the stub shaft, straight spline-coupled to the pinion shaft, and a first clutch mechanism is provided between the movable body and one of the driven gears. A power steering device comprising a second clutch mechanism provided between a body and another driven gear. 3. A steering torque sensor is provided on both sides of a projection provided on the movable body according to claim 1 or 2, and drive control of a drive bevel gear is performed in accordance with an output signal of the torque sensor. A power steering device characterized by the following.