JPH0656044A - Motor-driven rear wheel steering device - Google Patents

Abstract

PURPOSE:To provide a motor-driven rear wheel steering device wherein a meshing noise is reduced while eliminating uneven wearing in a tooth surface of a gear by stabilizing meshing of the hypoid gear to improve output efficiency. CONSTITUTION:In an electrically-operated rear wheel steering device comprising a hypoid gear pinion 10 integrally rotated with an output shaft 2 of an electric motor (m), hypoid gear 13 meshed with this hypoid gear pinion 10, hypoid gear wheel 23 integrally formed with this hypoid gear 13 and a transmitting means for transmitting turning force of the hypoid gear wheel 12 to a rod, the steering device is constituted by providing an elastic unit of spring of the like, which applied elastic force to act in the axial direction of the hypoid gear wheel, in the hypoid gear wheel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the output efficiency of a hypoid gear that transmits the rotation of an electric motor to a rod in an electric rear wheel steering system.

[0002]

2. Description of the Related Art A conventional rear wheel steering system shown in FIGS. 2 and 3 is a hypoid gear pinion in which an electric motor m is provided on one side of a casing 1 and a large diameter portion 3 is formed on an output shaft 2 of the electric motor m. The shaft 4 is connected. Ball bearings 5 and 6 for radial load are provided on both left and right sides of the hypoid gear pinion shaft 4, and bearings 7 and 8 for thrust load are provided on both side surfaces of the large diameter portion 3. Then, an adjusting screw 9 is provided on the outer circumference of the ball bearing 5, the adjusting screw 9 is screwed to the casing 1 to hold the ball bearing 5, and the tip of the adjusting screw 9 is opposed to the bearing 7. The amount of pressurization applied to the bearings 7 and 8 is adjusted.

Therefore, the hypoid gear pinion shaft 4
Is rotatably supported by the ball bearings 5 and 6, and the acting force in the thrust direction acting on the hypoid gear pinion shaft 4 is received by the bearings 7 and 8. A hypoid pinion 10 is formed on the hypoid gear pinion shaft 4 as described above, and the hypoid pinion 10 is engaged with a hypoid gear 13 formed on a hypoid gear wheel 12 provided in a gear box portion 11 of the casing 1. Further, while the support shaft 14 is fitted into the hypoid gear wheel 12,
The tip is projected upward, and the projecting end is rotatably inserted into the axial center portion of the cover 15 mounted on the gear box portion 11 via a needle bearing 16 for radial load.

A step portion 17 of the hypoid gear wheel 12 is formed on the side opposite to the support shaft 14.
Between the gear box 11 and the gear box 11 for thrust load
8 is provided, and a needle bearing 20 for radial load is fitted between the outer periphery of the small diameter portion 19 formed on the lower side and the gear box 11, and the hypoid gear wheel 12 is fitted with these bearings 18, 20 and the support shaft 14. It is rotatably supported. In the hypoid gear wheel 12 rotatably supported in this manner, the spherical bearing 21 is fitted to the inner circumference of the small diameter portion 19. The axial center of the spherical bearing 21 is eccentric to the axial center of the hypoid gear wheel 12 by an eccentric amount e.

Then, one side of the stud shaft 22 is fitted into the spherical bearing 21, and the tapered portion 22a formed at the tip thereof is formed in the rod 23 and the tapered hole 23a is formed.
And the stud shaft 22 is fastened to the rod 23. As described above, the spherical bearing 21, the stud shaft 22, and the like serve as transmission means for transmitting the rotation of the hypoid gear wheel 12 to the rod 23. Reference numerals a and b are potentiometers, a is associated with the support shaft 14 to detect the rotation angle of the hypoid gear wheel, and b is the rod 2
3 is detected and the information is fed back to a controller (not shown). Then, the controller comprehensively determines these pieces of information and other information such as the steering angle of the front wheels and the vehicle speed, and controls the rotation of the electric motor m so that optimum steering can be performed.

In such a structure, when the electric motor m rotates, the hypoid gear pinion shaft 4 rotates and the hypoid gear wheel 12 rotates with the rotation of the hypoid gear pinion shaft 4. When the hypoid gear wheel 12 rotates, the stud shaft 22 rotates about the axis of the hypoid gear wheel 12. The stud shaft 22 that rotates in this way
Is absorbed by the spherical bearing 21 in a motion other than the linear direction along the axis of the rod 23, so that the stud shaft 22 eventually moves the rod 23 in the axial direction. Then, depending on the moving direction of the stud shaft 22, the rod 23 moves to the left or right in the drawing, and the rod 23
The rear wheels are steered via side rods (not shown) connected to both ends of the rear wheel.

[0007]

In such a conventional electric type rear wheel steering system, the rotation of the electric motor m is controlled by the rod 23.
The hypoid gear 13 is used to transmit to the hypoid gear 13.
Since the hypoid gear wheel 12 having a diameter larger than that of the hypoid pinion 10 is engaged in the offset state, a large moment force acts in the axial direction on the engaging portion of the hypoid gear wheel 12.
Further, the hypoid gear wheel 12 and its supporting shaft 14
Needle bearing 2 for radial load to support and
Although 0 and 16 are provided, since these needle bearings are bearings in which needles as rollers are in line contact, there is play in the radial direction and friction loss is large.

In such a structure, when the electric motor m is rotated to drive the hypoid gear 13, the hypoid gear wheel 12, which is prone to tilt due to the play of the needle bearings 16 and 20, is the hypoid pinion 1.
Since it meshes with 0 in the offset state, it is inclined by the moment force acting on the meshing portion. For this reason, the hypoid gear wheel 12 rotates while engaging with the hypoid pinion 10 while tilting, resulting in a reduction in output efficiency, uneven wear of the tooth surfaces of both gears, and a large meshing sound. There was a problem. An object of the present invention is to provide an electric rear wheel steering system in which the meshing of the hypoid gear 13 is stabilized and the output efficiency is improved.

[0009]

In order to solve the above-mentioned problems, according to the present invention, a hypoid pinion that rotates integrally with an output shaft of an electric motor, a hypoid gear engaged with the hypoid pinion, and a hypoid gear integrally formed with the hypoid gear. In an electric rear wheel steering system including a wheel and a transmission means for transmitting a rotational force of the hypoid gear wheel to a rod, the hypoid gear wheel is provided with an elastic body such as a coil spring for exerting an elastic force in its axial direction. It has a structure.

[0010]

With the above construction, the elastic force of the elastic body such as the coil spring acts in the axial direction of the hypoid gear wheel. Since the hypoid gear wheel is constantly pushed in the axial direction by this force, even if a moment force acts on the meshing part of the hypoid gear wheel in the direction of tilting the hypoid gear wheel, the elastic force of this elastic body causes the moment force to change. Press the hypoid gear wheel against it, parallel to its axis. Therefore, the hypoid gear wheel does not tilt.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. here,
A coil spring 24 as an elastic body is provided on the support shaft 14 of the hypoid gear wheel 12, and the coil spring 24 is sandwiched between the hypoid gear wheel 12 and the cover 15 to be bent, and the hypoid gear pinion shaft 4 and the hypoid gear wheel 12 are supported. The difference from the above-mentioned conventional example is that the bearing is changed. Since the other components are almost the same as those of the conventional example, the description will be focused on this difference, and the common components will be denoted by the same reference numerals and detailed description thereof will be omitted.

The first difference is that the hypoid gear 13
Are supported by bearings as follows. That is, the hypoid gear pinion shaft 4 attached to the output shaft 2 of the electric motor m is supported by the casing 1 by the ball bearings 25 and 26 for radial load. These ball bearings 25, 2
6, the ball bearing 25 on the electric motor m side has a flange 27 formed on the hypoid gear pinion shaft 4,
It is sandwiched between a ring 28 for fixing the ball bearing 25 and is supported by the casing 1 by a nut 29. In this case, the inner race of the ball bearing 25 abuts and supports the flange 27 and the nut 29, and
The outer race abuts on and supports the ring 28 and the annular convex portion 30 of the casing 1. By supporting the ball bearing 25 and the ball bearing 26 in the casing 1 in this way, the thrust load acting on the hypoid gear pinion shaft 4 can be supported, and the clearances of the conventional thrust load bearings 7 and 8 can be supported. There is no need to adjust the number of parts, and the number of parts has decreased accordingly.

The hypoid gear wheel 12 is supported by ball bearings 31 and 32 for radial load. That is, the ball bearing 31 is provided between the support shaft 14 and the cover 11, but the outer race thereof is supported by being brought into contact with the annular step portion 33 of the cover 11.
Further, the ball bearing 32 is used for the hypoid gear wheel 12
The small diameter portion 19 is provided at the bottom of the
The outer race end is brought into contact with the step portion 17 of the hypoid gear wheel 12 so that the gear box portion 11 of the casing 1
To support. In this way, the ball bearings 31, 32
Since the hypoid gear wheel 12 is supported by the casing 1, it is possible to support the thrust load of the hypoid gear wheel 12 at the same time, and due to the characteristics of the ball bearing whose contact surface is a ball, there is less play and less friction. The hypoid gear wheel 12 can also rotate smoothly without backlash.

The second difference is that an elastic body is provided for pressing the hypoid gear wheel 12 in its axial direction. That is, the coil spring 24 is provided on the support shaft 14 of the hypoid gear wheel 12, and the coil spring 24 is bent between the hypoid gear wheel 12 and the cover 15. In this way, the elastic force of the flexed coil spring 24 acts in the axial direction of the hypoid gear wheel 12 (downward in the figure), and the entire hypoid gear wheel 12 is constantly pressed in the axial direction. Therefore, even if the moment force acting in the direction of tilting the hypoid gear wheel 12 acts on the meshing portion of the hypoid gear wheel 12 meshing in the offset state, the coil spring 2
The elastic force of 4 opposes this moment force and pushes the hypoid gear wheel 12 in the axial direction so as not to tilt it.

As described above, since the hypoid gear wheel 12 is supported by the ball bearings 31 and 32 instead of the needle bearings 16 and 20 of the conventional example, the hypoid gear wheel 12 is supported without rattling, so that it is difficult to tilt. In addition, since the hypoid gear wheel 12 is pressed in the axial direction by the coil spring 24, the hypoid gear wheel 12 does not tilt even if a moment force acts on the meshing portion in the offset state. Therefore, even when the electric motor m is rotated, the output efficiency does not decrease. Further, as described above, since the hypoid gear wheel 12 does not incline and engage with each other, uneven wear of the tooth surface is eliminated, the durability of the hypoid gear 13 is improved, and a large engagement noise is eliminated.

[0016]

[Effect] Since the elastic force of the elastic body such as the spring acts in the axial direction of the hypoid gear wheel, even if a moment force acts in the direction in which the hypoid gear wheel is tilted, the elastic force of the elastic body causes the hypoid gear wheel to move in the axial direction. It is not pressed against and tilts. In this way, the hypoid gear wheel does not tilt at its meshing portion, so that the output efficiency of the electric motor does not decrease even when the electric motor is rotated. In addition, since the hypoid gear wheel does not tilt, uneven wear on the tooth surface is eliminated, the durability of the hypoid gear is improved, and a loud meshing noise is eliminated.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 is a front sectional view of a conventional example.

3 is a sectional view taken along line III-III in FIG.

[Explanation of symbols]

 2 Output shaft 10 Hypoid gear pinion 12 Hypoid gear wheel 13 Hypoid gear 23 Rod 24 Coil spring m Electric motor

Claims (1)

[Claims] 1. A hypoid pinion that rotates integrally with an output shaft of an electric motor mounted in a casing, a hypoid gear engaged with the hypoid pinion, and a hypoid gear wheel integrally formed with the hypoid gear.
In an electric rear wheel steering system including a transmission means for transmitting the rotational force of the hypoid gear wheel to a rod, the hypoid gear wheel is provided with an elastic body such as a coil spring for exerting an elastic force in the axial direction thereof. Electric rear wheel steering system.