JP3552476B2 - Electric power steering - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric power steering apparatus that assists a steering force of a steering wheel.
[0002]
2. Description of the Related Art An electric power steering apparatus that detects a torque applied to a steering wheel and obtains an assisting force corresponding to the torque by an electric motor is well known. In this electric power steering device, a hypoid pinion for transmitting rotation of an electric motor to a hypoid gear provided on an output shaft is divided from a motor shaft, and a hypoid pinion coupled with a coupling, a motor shaft split type, and a hypoid 2. Description of the Related Art Two types of a single motor type in which a pinion is integrally formed on a motor shaft are known.
[0003]
A hypoid pinion and a motor shaft split type electric power steering apparatus will be described with reference to FIG. An input shaft 1 for transmitting rotation from a handle to a rack housing 10, an output shaft 2 having a hypoid gear 9 connected to the input shaft 1 via a torsion bar 3 so as to be relatively rotatable, and a rotation of the torsion bar 3. A torque sensor 4 for detecting torque as a relative rotational displacement between the input shaft 1 and the output shaft 2 and a rack shaft 5 of a steering mechanism meshing with a pinion 2a provided on the output shaft 2 are provided internally. An electric motor 15 which is disposed in an axial direction orthogonal to the axis of the input shaft 1 and the output shaft 2 and in which a hypoid pinion 17 meshing with the hypoid gear 9 is coupled to a motor shaft 14 by a coupling 18. Is transmitted to the rack shaft 5 via a pinion 2 a provided on the output shaft 2.
[0004]
The rack shaft 5 is pressed against the pinion 2a by a rack guide 6 pressed by a spring 7 in a meshing direction with an appropriate pressing force. A steering angle detector 12 such as an encoder or a potentiometer is connected to the pinion 2a via a gear 11.
[0005]
Further, as means for adjusting the backlash between the hypoid gear 9 and the hypoid pinion 17, a first spacer 20 is interposed in an axially opposed portion between the hypoid gear 9 and the output shaft 2, and meshes with the rack shaft 5. A second spacer 21 having a selected thickness is used between the bearing 8 at the end of the output shaft 2 on the side of the pinion 2a and the rack housing 10 so that the backlash is appropriate, and the second spacer 21 is screwed to the rack housing 10. The configuration is such that the bearing 8 is moved in the axial direction by the nut cover 22.
[0006]
On the other hand, as shown in FIG. 6, the electric power steering device of the single motor type has the same basic configuration as the hypoid pinion of FIG. 5 and the electric power steering device of the motor shaft split type, but has a hypoid pinion. Reference numeral 17 denotes a structure formed integrally with the motor shaft 14 of the motor 13.
[0007]
[Problems to be solved by the invention]
In the electric power steering apparatus of the hypoid pinion and the motor shaft split type shown in FIG. 5 described above, the bearing 16 and the rack for supporting the motor shaft 14 on the motor housing 15 side are provided at the male and female fitting portions of the rack housing 10 and the motor housing 15. Two bearings are required on the housing 10 side for supporting the hypoid pinion 17 and the cost is high. In addition, play is likely to occur at the connection between the hypoid pinion 17 and the coupling 18 of the motor shaft 14, which causes noise. In order to prevent the backlash, the connection portion and the centering of the hypoid pinion 17 and the motor shaft 14 are processed with high precision or an elastic body is interposed, but this also increases the cost.
[0008]
In addition, in the electric power steering apparatus of the single motor type shown in FIG. 6, the motor shaft 14 integrally formed with the hypoid pinion 17 is supported on the rack housing 10 by one bearing 19, and the hypoid pinion 17 and the hypoid gear Although the meshing with the motor 9 is good, there is a problem that it is difficult to measure the performance of the motor alone because the bearing 19 is provided on the rack housing 10 side.
[0009]
Further, in the backlash adjusting means in the hypoid pinion and the electric power steering device of any of the motor shaft split type and the motor single type, when there is a backlash, the hypoid gear 9 starts rotating when the hypoid gear 9 starts to rotate, and the reverse input causes the hypoid gear 9 to rotate. At the start, a tooth contact noise with the hypoid pinion 17 is generated and transmitted to the vehicle interior. Before mounting the second spacer 21, necessary dimensions of each part are measured to obtain a proper thick second spacer 21. Must be selected, it takes time to assemble, and it is necessary to prepare various thick second spacers 21.
[0010]
An object of the present invention is to enable performance measurement of a single motor in an electric power steering device of a single motor type, and to adjust backlash of a hypoid gear and a hypoid pinion in a short time without using various thick spacers. It is easy to do.
[0011]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a hypoid gear connected to an input shaft for transmitting rotation from a handle to a rack housing and to the input shaft for relative rotation via a torsion bar. An output shaft, a torque sensor that detects the rotational torque of the torsion bar as a relative rotational displacement between the input shaft and the output shaft, and a rack of a steering mechanism that meshes with a pinion provided on the output shaft. An electric motor having a shaft disposed therein, disposed in an axial direction intersecting the axis of the input shaft and the output shaft, and having a hypoid pinion meshing with the hypoid gear on a motor shaft; and rotating the electric motor to the output shaft. An electric power steering apparatus for transmitting power to a rack shaft via a pinion provided, wherein the rack housing and the motor housing Preparative fitted male and female, male and female over the fitting portion is provided a bearing for supporting the motor shaft, in which the bearing is supported on the female element side and the male element side of said male and female fitting portion.
[0012]
According to a second aspect of the present invention, in the configuration according to the first aspect, a bearing at an output shaft end on a pinion side meshing with the rack shaft is held by a bearing case screwed into a rack housing, and the movement of the bearing case causes the hypoid gear and the hypoid gear to move. The backlash of the hypoid pinion is adjustable.
[0013]
According to a third aspect, in the configuration according to the first aspect, the hypoid gear is provided on the output shaft so as to be slidable only in the axial direction, and the hypoid gear is biased between the hypoid gear and the output shaft in a meshing direction of the hypoid pinion. A spring is interposed to absorb the backlash between the hypoid gear and the hypoid pinion, and the hypoid gear or the output shaft is provided with a cushioning material for buffering the contact between the hypoid gear and the output shaft.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, an input shaft 1 for transmitting rotation from a handle to a rack housing 10, an output shaft 2 provided with a hypoid gear 9 connected to the input shaft 1 via a torsion bar 3 so as to be relatively rotatable, and the torsion A torque sensor 4 for detecting the rotational torque of the bar 3 as a relative rotational displacement between the input shaft 1 and the output shaft 2, a rack shaft 5 of a steering mechanism meshing with a pinion 2a provided on the output shaft 2, Is installed inside.
[0015]
Reference numeral 13 denotes an electric motor 13, which is disposed in an axial direction orthogonal to the axes of the input shaft 1 and the output shaft 2, and a motor shaft 14 integrally formed with a hypoid pinion 17 that meshes with the hypoid gear 9. The rotation of the electric motor 13 is transmitted to the rack shaft 5 via a pinion 2 a provided on the output shaft 2.
[0016]
The rack shaft 5 is pressed against the pinion 2a by a rack guide 6 pressed by a spring 7 in a meshing direction with an appropriate pressing force. A steering angle detector 12 such as an encoder or a potentiometer is connected to the pinion 2a via a gear 11.
[0017]
The electric power steering device having the above configuration is a single motor type. According to the present invention, in the electric power steering apparatus, the rack housing 10 and the motor housing 15 are male and female fitted, and the bearing 19 of the motor shaft 14 is provided in the male and female fitting part.
[0018]
That is, the rack housing 10 is provided with the female element 10a, the motor housing 15 is provided with the male element 15a, and the female element 10a and the female element 15a are fitted to connect the motor housing 15 to the rack housing 10. The rack housing 10 may be provided with a male element, and the motor housing 15 may be provided with a female element.
[0019]
In this configuration, a bearing 19 is mounted on the male / female fitting portion between the female element 10a and the male element 15a over the female element 10a and the male element 15a.
[0020]
According to the above configuration, there is no misalignment between the hypoid pinion and the motor shaft, which is a characteristic of the electric power steering device of the motor single type, no rattling due to the misalignment, and the female element 10a of the rack housing 10 The half and the male element 15a of the motor housing 15 are supported half by one, so that the alignment between the hypoid gear 9 and the hypoid pinion 17 is reliably obtained, and the gear noise between the hypoid gear 9 and the hypoid pinion 17 is reduced.
[0021]
Further, since the bearing 19 is half supported by the male element 15a on the motor housing 15 side, there is an advantage that the performance measurement of the motor alone can be easily performed.
[0022]
FIG. 2 shows the second embodiment. The basic configuration of the electric power steering apparatus according to the second embodiment is the same as that of the first embodiment in FIG. In the electric power steering apparatus according to the second embodiment, which has the same basic configuration as the first embodiment, a spacer 20 is interposed between the output shaft 2 and the hypoid gear 9 in the axial direction. Then, the bearing 8 at the end of the output shaft 2 on the pinion 2 a side meshing with the rack shaft 5 is held by a bearing case 23 screwed to the rack housing 10 and the nut cover 22, and the bearing case 23 is locked by a lock sleeve 24. The configuration is as described above.
[0023]
In the above configuration, the backlash of the hypoid gear 9 and the hypoid pinion 17 can be adjusted by moving the bearing case 23 in the axial direction of the output shaft 2 by the screw lead, and the backlash can be adjusted in a short time. In addition, various types of thick spacers are not required, and the cost can be reduced.
[0024]
3 and 4 show a third embodiment. The basic structure of the electric power steering apparatus according to the third embodiment is the same as that of the first embodiment in FIG. In the electric power steering apparatus according to the third embodiment, the basic configuration is the same as that of the first embodiment. In the electric power steering apparatus, the hypoid gear 9 has a keyway on the output shaft 2 and a rotation direction associated with the keyway. The key is slidable only in the axial direction by the corresponding key.
[0025]
A flange 25 is provided at the upper end of the output shaft 2, and a spring 26 that presses and biases the hypoid gear 9 in the meshing direction of the hypoid pinion 17 is interposed between the flange 25 and the hypoid gear 9. The configuration is such that a buffer material 27 such as rubber or synthetic resin is provided to buffer the contact with the flange 25. The cushioning material 27 may be provided on the flange 25 side.
[0026]
In the above-described configuration, the hypoid gear 9 slides on the output shaft 2 by an axially equivalent amount of the proper backlash between the hypoid gear 9 and the hypoid pinion 17, stops on the shoulder of the hypoid pinion 17, and rotates with the proper backlash. Transmit power.
[0027]
When the hypoid gear 9 stops on the shoulder of the hypoid pinion 17 and compresses the spring 26, the shock absorbing material 27 absorbs the shock when the hypoid gear 9 comes into contact with the flange 25 of the output shaft 2.
[0028]
Therefore, it is possible to reduce the generation of abnormal noise due to the tooth contact when the rotation of the hypoid pinion 17 and the hypoid gear 9 is started.
[0029]
【The invention's effect】
As described above, according to the present invention, the electric power steering apparatus can be downsized, the alignment of the hypoid gear and the hypoid pinion can be reliably obtained, and the gear noise between the hypoid gear and the hypoid pinion can be obtained. This has the advantage that the performance can be easily measured with the motor alone.
[0030]
In addition, in the configuration of claim 2, in addition to the advantages of the configuration of claim 1, the backlash of the hypoid gear and the hypoid pinion can be adjusted in a short time, and various types of thick spacers are not required, and cost is reduced. Can be reduced.
[0031]
Further, in the configuration of claim 3, in addition to the advantage of the configuration of claim 1, the backlash amount of the hypoid gear and the hypoid pinion is appropriately and automatically adjusted, and the abnormal noise due to the tooth contact when the hypoid pinion and the hypoid gear start rotating respectively. Can be reduced.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a first embodiment of the device of the present invention. FIG. 2 is a sectional view showing a second embodiment of the device of the present invention. FIG. 3 is a third embodiment of the device of the present invention. FIG. 4 is a cross-sectional view of a main part of a third embodiment of the present invention. FIG. 5 is a cross-sectional view of a conventional hypoid pinion and a motor shaft split type electric power steering device. Sectional view of a conventional electric power steering device with a single motor [Description of reference numerals]
DESCRIPTION OF SYMBOLS 1 Input shaft 2 Output shaft 2a Pinion 3 Torsion bar 4 Torque sensor 5 Rack shaft 8 Bearing (of output shaft)
9 Hypoid gear 10 Rack housing 10a Female element 12 Steering angle detector 13 Electric motor 14 Motor shaft 15 Motor housing 15a Male element 17 Hypoid pinion 19 Bearing (of motor shaft)
Reference Signs List 20 spacer 22 nut cover 23 bearing case 24 lock sleeve 25 flange 26 spring 27 cushioning material

Claims (3)

An input shaft for transmitting rotation from a handle to a rack housing, an output shaft having a hypoid gear connected to the input shaft so as to be relatively rotatable via a torsion bar, and outputting a rotational torque of the torsion bar to the input shaft. A torque sensor that detects a relative rotational displacement with respect to a shaft, and a rack shaft of a steering mechanism that meshes with a pinion provided on the output shaft are provided therein, and an axis that intersects the axes of the input shaft and the output shaft. Motor provided with a hypoid pinion that meshes with the hypoid gear on a motor shaft, and an electric power steering device that transmits the rotation of the electric motor to a rack shaft via a pinion provided on the output shaft. , The rack housing and the motor housing are male and female fitted, and the motor shaft is A bearing for lifting provided, electric power steering apparatus characterized by the bearing is supported on the female element side and the male element side of said male and female fitting portion. The bearing of the output shaft end of the pinion side which meshes before Symbol rack shaft is held by a bearing case screwed to the rack housing, and characterized in that adjustable backlash of the hypoid gear and the hypoid pinion by the movement of the bearing case The electric power steering apparatus according to claim 1, wherein Before SL provided only slidably in the axial direction on the output shaft of the hypoid gear, absorb backlash interposed a spring hypoid gear and the hypoid pinion to press urging the hypoid gear in the engagement direction of the hypoid pinion between the hypoid gear and the output shaft 2. The electric power steering apparatus according to claim 1 , wherein the hypoid gear or the output shaft is provided with a cushioning material for buffering contact between the hypoid gear and the output shaft.

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