JPH05310138A - Steering mechanism for vehicle - Google Patents

Abstract

PURPOSE:To suppress a small movement in the rotational and radial direction at the shaft center of a rack and to lighten a steering mechanism weight in a steering mechanism for a vehicle constituted so that two pinions gear into a rack shaft for turning the direction of a steering wheel. CONSTITUTION:A steering mechanism is provided with a rack shaft 4 which is provided with the first rack gear part and the second rack gear part and turns the direction of a steering wheel, the first pinion shaft 1 and the second pinion shaft 2 which gear into the first and the second rack gear parts of the rack shaft 4 respectively to actuate the rack shaft 4 to stroke in axial direction during turn, and a rack presser 7 which energizes the rack shaft 4 so as to adjust the gearing condition of the first and the second rack gear parts with the first and the second pinion shafts 1, 2. The first and the second pinion shafts 1, 2 are arranged with a mutually crossing angle of 90 deg. and the rack presser 7 is arranged to energize a rack shaft 4 in the middle direction between the first pinion shaft 1 and the second pinion shaft 2, and at least a contact surface.between the rack shaft 4 and the rack presser 7 is formed into a flat surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering mechanism,
It is effective for use in a power steering device or the like for reducing the steering force of a vehicle.

[0002]

2. Description of the Related Art Conventionally, in a steering mechanism having a rack-and-pinion structure, a rack holder supported by a spring is used to keep a constant backlash between the rack and the pinion. This rack suppression is, for example,
As shown in Japanese Patent Laid-Open No. 52-52, it has a concave arc shape with respect to a cylindrical rack, and is arranged so as to urge the rack in the pinion direction by a spring.

[0003]

Here, the conventional rack retainer is provided at a position facing the pinion via the rack. That is, since the rack retainer presses the rack from the side opposite to the pinion, when two pinions are present, two rack retainers are required, resulting in an increase in weight and a complicated structure.

Further, the rack not only moves only in the axial direction but also rotates and moves slightly in the radial direction in response to the rotation of the pinion. As a result, there is a problem that the meshing state between the rack and the pinion is out of order.

The present invention has been made in view of the above points, and in a steering mechanism of a vehicle in which two pinions are meshed with a rack shaft that turns the direction of steering wheels, a small amount in the radial direction of the rack is provided. It is an object of the present invention to provide a vehicle steering mechanism capable of suppressing various rotations and movements and also reducing the weight of the steering mechanism.

[0006]

In order to achieve the above object, in a vehicle steering mechanism according to the present invention, a rack shaft having first and second rack tooth portions and turning a steering wheel direction is provided. , First and second pinions that mesh with the first and second rack tooth portions of the rack shaft respectively to stroke the rack shaft in the axial direction during rotation, and the first and second rack tooth portions. And a rack retainer for urging the rack shaft so as to adjust the meshing state between the first and second pinions, and the first and second pinions are arranged at a predetermined intersection angle, and A rack retainer is arranged to bias the rack shaft toward an intermediate direction between the first pinion and the second pinion.

[0007]

With the above construction, the meshing state of the rack can be adjusted by pressing one rack with respect to two pinions. Therefore, the configuration of the steering mechanism is simplified and the weight can be reduced.

Further, the first and second pinions are arranged with a predetermined crossing angle, and the rack retainer is arranged so as to urge the rack toward an intermediate direction between the first pinion and the second pinion. .. Therefore, it is possible to press the rack from three directions, and it is possible to suppress minute rotation and movement of the rack in the radial direction.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b) are front views showing main components when the present invention is applied to a power steering device,
It is a side view.

In FIGS. 1A and 1B, the first pinion shaft 1 is connected to a steering handle (not shown), rotates according to the rotation of the steering handle, and rotates via a bearing 15 in the housing 13. It is supported freely. The pinion teeth of the first pinion shaft 1 mesh with the first rack teeth formed on the rack shaft 4. The first rack tooth portion is formed by cutting a groove as a tooth portion on the flat surface of the rack shaft 4. The bearing 15 is preloaded in order to restrict the axial movement of the first pinion shaft 1.
The preload adjustment is performed by the bolt 16 and the bolt 16
A bolt 17 is attached to prevent the loosening.

The motor 3 is fixed to the housing 13 by four bolts 25. A clutch 23 is attached to the tip of the output shaft of the motor 3. The clutch 23 is driven by a control device (not shown) and makes frictional contact with a clutch plate 22 mounted on the worm 5 by bolts 24. As a result, the worm 5 rotates as the motor 3 rotates. The control device controls to disconnect the clutch 23 and the clutch plate 22 when it is determined that the motor 3 has failed. Further, the control device inputs detection signals from a vehicle speed sensor, a steering angle sensor, a torque sensor, etc., which are not shown. Then, the control device recognizes the driving state of the vehicle from the detection signal, and drives the motor 3 so as to apply the steering assist force most suitable to the driving state. It should be noted that detailed control contents are omitted because they are publicly known.

The worm 5 has two sets of bearings 18, 19
It is rotatably supported by the housing 13 via.
The two sets of bearings 18 and 19 are preloaded to regulate the axial movement of the worm 5, and the preload is adjusted by the two sets of nuts 20 and 21. A worm wheel 6 is meshed with the worm 5, and the worm 5 and the worm wheel 6 constitute a speed reduction mechanism. The second pinion shaft 2 is coaxially attached to the worm wheel 6.

Both ends of the second pinion shaft 2 are supported by bearings 26 and 27, and rotate with the rotation of the worm wheel 6. The axial movement of the second pinion shaft 2 is adjusted by the nuts 28 and 29. The pinion teeth of the second pinion shaft 2 mesh with the second rack teeth formed on the rack shaft 4. Like the first rack tooth portion, the second rack tooth portion is also formed by cutting a groove as a tooth portion on a flat surface.

As shown in FIG. 2, the rack retainer 7 applies a preload to the spring 30 so that the rack shaft 4 is
It is pressed against the flat portion cut into two to adjust the backlash between the rack shaft 4 and the pinion shafts 1 and 2. A rectangular recess is provided at the center of the rack holder 7, and a corresponding protrusion is provided on the rack shaft 4. The recess of the rack retainer 7 and the protrusion of the rack shaft 4 are fitted to each other to prevent rotation of the rack shaft 4 about its axis. The rack retainer 7 rotates on a fixed shaft 8 via a bearing 10. The fixed shaft 8 is attached to a fixed base 9. A bearing 11 is provided between the fixed base 9 and the rack retainer 7 to restrain the axial movement of the rack retainer 7. The thin flat plate 12 is disposed between the bearing 10 and the bearing 11, and preloads the bearing 10. Then, it rotates around the fixed shaft 8 together with the rack holder, the outer ring of the bearing 11, and the bearing 10.

The spring 30 is held by a bolt 31 attached to the housing 13, and this bolt 3
1 makes it possible to adjust the preload of the spring 30. In order to prevent the bolt 31 from loosening, the nut 3
2 is attached.

The operation of this embodiment configured as described above will be described. Steering force from a steering handle (not shown) is transmitted to the rack shaft 4 via the first pinion shaft 1. On the other hand, the driving force of the motor 3 that assists the steering force is generated by the clutch mechanism including the clutch 23 and the clutch plate 22, the worm 5, and the worm wheel 6.
And is transmitted to the rack shaft 4 via the second pinion shaft 2.

Here, the rack shaft 4 is formed with a first rack tooth portion for the first pinion shaft 1 and a second rack tooth portion for the second pinion shaft 2, and each has a noise.・ To reduce vibration, helical gears are used. In this case, in FIG. 3, when the force applied from the pinion tooth portions of the first and second pinion shafts 1 and 2 to the rack tooth portion of the rack shaft 4 is F, the rack shaft 4 is attached to the rack shaft 4 in the axial direction. In addition to the force for making the stroke, the X-direction component force Fp and the Y-direction component force Fr, which are the rotational force about the axis and the moving force in the radial direction, are generated. Therefore, even if a conventional rack holder is provided, the rack shaft 4 is slightly rotated about the shaft center by the two forces Fp and Fr and is also slightly moved in the radial direction. As a result, there is a problem that the meshing state between the rack and the pinion is disturbed, and the steering feel is deteriorated.

Therefore, in this embodiment, the rack shaft 4 is sandwiched from three directions in consideration of the balance of forces in order to prevent a minute rotation of the center of the rack shaft 4 and a minute movement in the radial direction. , The first and second pinion shafts 1 and 2 and the rack holder 7 are arranged. In this case, it is desirable to form the first and second rack tooth portions so that the angles formed by the rack tooth surfaces are at right angles, in order to facilitate machining of the rack tooth surfaces. Then, the first and second pinion shafts 1 and 2 are arranged at an intersection angle of 90 ° so as to be orthogonal to each other when viewed from the side surface, corresponding to the first and second rack tooth portions. The rack retainer 7 includes the first and second pinion shafts 1,
It is provided at an intermediate position forming an angle of 45 ° with respect to both of the two. As a result, the backlash with the rack shaft 4 can be adjusted with only one rack holder 7 for the two pinion shafts 1 and 2, and the number of parts can be reduced and the weight can be reduced. it can.

In particular, in this embodiment, when the rack shaft 4 is sandwiched from three directions, the contact surfaces of the first and second pinion shafts 1 and 2 and the rack retainer 7 are flat. Therefore, even when the X-direction component force Fp and the Y-direction component force Fr are generated, it is possible to effectively prevent rotation of the rack shaft 4 about its axis and radial movement.

The present invention is not limited to the above embodiment,
Various modifications can be made without departing from the spirit of the present invention.
It is also possible to replace it with a pair of rack pressing rollers 33. In this case, the two sets of rack pressing rollers 33 are configured to be rotatable in the axial direction of the rack shaft 4 and
Are symmetrically arranged to be biased from different directions.

Further, as in the above-described embodiment, the bearing 11 between the rack retainer 7 and the fixed shaft 8 is eliminated, and both are fitted with an appropriate rotatable tolerance. As a result, it is possible to reduce the number of parts.

Further, in the above-mentioned embodiment, the example in which the present invention is applied to the power steering device is shown, but the present invention can be applied to various power transmission mechanisms having a helical rack such as a rear wheel steering device. ..

[0023]

As described in detail above, in the vehicle steering mechanism according to the present invention, the meshing state of the two pinions and the rack can be adjusted by the single rack retainer.
The structure of the steering mechanism is simplified, and the weight can be reduced.

Further, since the rack is constructed so as to be restrained from three directions by the first and second pinions and the rack restrainer, it is possible to restrain the rotation of the center of the rack axis and the radial movement thereof.

[Brief description of drawings]

FIG. 1 is a front view and a side view showing main components when the present invention is applied to a power steering device.

FIG. 2 is a cross-sectional view showing a structure of a rack retainer.

FIG. 3 is an explanatory diagram illustrating a principle of causing minute rotation / movement of a rack shaft in a radial direction.

FIG. 4 is a cross-sectional view showing the structure of another embodiment of the rack retainer.

[Explanation of symbols]

 1 1st pinion shaft 2 2nd pinion shaft 3 Motor 4 Rack shaft 5 Worm 6 Worm wheel 7 Rack retainer 8 Fixed shaft 9 Fixed base 10 Bearing 11 Bearing

Claims (3)

[Claims] 1. A rack shaft having first and second rack tooth portions for turning the direction of a steered wheel, and a first and a second rack tooth portion of the rack shaft respectively meshing with each other, and at the time of rotation. In order to adjust the meshing state of the first and second pinions that stroke the rack shaft in the axial direction, and the first and second rack tooth portions and the first and second pinions, the rack shaft is adjusted. A rack retainer for urging the first and second pinions arranged at a predetermined crossing angle, and the rack retainer extends in an intermediate direction between the first pinion and the second pinion. A steering mechanism for a vehicle, wherein the steering mechanism is arranged to urge the vehicle. 2. The contact surface between the rack shaft and the rack presser is flat when the rack presser contacts the rack shaft and biases the rack shaft. Vehicle steering mechanism. 3. The first pinion is connected to a steering handle, and the second pinion is connected to an output shaft of a driving force generating means provided to assist the steering force. The vehicle steering mechanism according to claim 1, wherein the steering mechanism is a vehicle.