JP2005119578A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device having two motors which prevents a play between drive gears rotated together with the two motors and a driven gear engaged with the drive gear. <P>SOLUTION: The electric power steering device Ps comprises a driven gear (15) connected to a steering mechanism, a pair of drive gears (30 and 31) facing each other and engaged with the driven gear (15), a pair of motors Ma and Mb to drive the drive gears (30 and 31), and elastic bodies 32, 33, 34 and 35 which are provided at both ends of the drive gears (30 and 31) and disposed opposite to each other across a spindle (7) of the driven gear (15) while being different in deformation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electric power steering device mounted on an automobile.

  There are various types of gear boxes in the conventional electric power steering apparatus. A typical example of such a gear box is a pinion assist type electric power steering device that assists a manual steering force of a steering handle by a motor provided on a pinion shaft interlocked with a steering shaft to steer a wheel (for example, Patent Document 1).

The pinion assist type electric power steering device includes a rack shaft provided with a rack, and a worm wheel of a rack and pinion type gear box that is provided on a steering shaft that drives the rack shaft and includes a pinion shaft having a pinion. A motor for driving the worm wheel and a reduction gear mechanism for reducing and rotating the rotation of the motor are included.
The worm wheel is driven by a motor through a reduction gear mechanism made of a worm, and performs steering assist according to the steering force of the steering handle.

Conventionally, the meshing portion between the worm and the worm wheel has a backlash (play) in order to prevent tooth bending and stagnation.
However, when the backlash is large, the worm and the tooth surface of the worm wheel collide to generate a hitting sound.
Therefore, in the electric electric power steering device disclosed in Patent Document 1, an elastic body is disposed between the bearing and the rotating shaft in order to suppress the hitting sound caused by the backlash of the meshing portion between the worm and the worm wheel. .
Japanese Patent No. 3253578 (paragraphs 0012 to 0014, FIGS. 2A, 2B, and 2C)

In the case of Patent Document 1, although the backlash is not reduced and the hitting sound is suppressed, the hitting sound still remains.
FIG. 8 is an explanatory view showing the structure of an electric power steering apparatus having two conventional motors.
Conventionally, power steering devices mounted on automobiles have attracted attention because of their lower carbon dioxide emissions compared to hydraulic systems and more suitable for advanced control than hydraulic systems. ing.
In a vehicle equipped with an electric power steering device, a vehicle with a high axial load such as an RV vehicle has a large assist torque as shown in FIG. 8 or even if one of the motors A is broken. In order to be able to be driven by only one other motor B, there is one equipped with two motors A and B.

A steering shaft (not shown) that rotates integrally with a steering handle (not shown) is connected to the pinion shaft 100 via a universal joint (not shown). The pinion shaft 100 is provided with a worm wheel 111 of a reduction gear mechanism 110 for reducing the rotation of the motors A and B. On the left and right sides of the worm wheel 111 as a driven gear, worms 112 and 113 as drive gears rotated in the same direction by two motors A and B are always meshed. Elastic bodies 121, 122, 123, and 124 having the same elastic force are disposed at both ends of the two worms 112 and 113, respectively.
Motors A and B of the same type with the same torque are used. If either motor A or B fails, the other one motor A or B can rotate the pinion shaft 100 with power. I have.

However, when the worm wheel 111 is in a straight traveling state, the elastic bodies 121, 122, 123, and 124 have a steering torque sensor (not shown) turned off, the motors A and B do not rotate, and the worms 112, The torque of 113 is 0 and is stationary. Since each elastic body 121, 122, 123, 124 has the same elastic force, the left worm 112 and the left worm 113 are pushed back to the center as shown in FIG. It has become.
For this reason, between the tooth surfaces of the worm wheel 111 and the worms 112 and 113, there are backlashes (plays) S1 and S2 for preventing tooth bending and squeaking noise, and hitting sounds are generated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electric power steering apparatus having two motors, which prevents rattling between a drive gear that rotates with the two motors and a driven gear that meshes with the drive. There is.

In order to solve the above-mentioned problem, an electric power steering apparatus according to claim 1, a driven gear coupled to a steering mechanism, a set of drive gears meshed with and opposed to the driven gear, An electric power steering apparatus including an elastic body provided at both ends and a set of motors for driving the drive gear, wherein the elastic body is disposed at an opposing position with a support shaft of the driven gear as a center. The amount of deformation of the elastic body is different.
Here, the drive gear refers to a drive gear that rotates using a motor as a drive source, and the driven gear refers to a driven gear that is rotated by the drive gear.

According to the first aspect of the present invention, when a set of motors rotates, the electric power steering apparatus rotates simultaneously with a torque applied to the set of drive gears to rotate the driven gear. Thereafter, if one set of motors stops, each drive gear also stops simultaneously. At this time, the electric power steering device is different in the repulsive force of the elastic body applied to each drive gear by making the deformation amount (displacement amount) of the elastic body arranged at the opposite position centering on the support shaft of the driven gear different. Therefore, each drive gear meshing with the driven gear stops in a shifted position state. For this reason, the drive gear pressed by the elastic body having a large repulsive force presses and rotates the tooth surface of the driven gear, and the drive gear pressed by the elastic body having a small repelling force rotates the tooth of the rotated driven gear. It stops with the surface in pressure contact.
Therefore, the driven gear is always supported by each drive gear when the drive gears are in pressure contact with each other. Therefore, the driven gear is always free of rattling, and no hitting sound is generated due to a tooth surface collision. In addition, the electric power steering apparatus can simplify the work of adjusting the backlash and the friction.

  The electric power steering apparatus according to claim 2, a driven gear connected to a steering mechanism, a set of drive gears meshed with the driven gear and opposed to each other, a set of motors driving the drive gear, The motor is characterized in that the motors have different torques.

According to the second aspect of the present invention, when the set of motors rotates, the electric power steering apparatus rotates simultaneously with the torque applied to the set of drive gears to rotate the driven gear. Thereafter, if one set of motors stops, each drive gear also stops simultaneously. At this time, since the motors have different torques, the rotational forces of the drive gears rotating together with the motors are also different, so that the stop positions of the drive gears are displaced. For this reason, the drive gear on the motor side having a large torque has a large rotational force and is stationary in a state where the tooth surface of the driven gear is pressed and rotated, and the drive gear on the motor side having a small torque is the driven gear that is rotated. The tooth surface is stationary with the pressure contact.
Therefore, the driven gear is always supported by each drive gear when the drive gears are in pressure contact with each other. Therefore, the driven gear is always free of rattling, and no hitting sound is generated due to a tooth surface collision. Thereby, the electric power steering apparatus can simplify the work of adjusting the backlash.

In the electric power steering apparatus according to the present invention, it is preferable that the drive gear is a worm and the driven gear is a worm wheel.
With such a configuration, the reduction gear mechanism can be configured with the minimum number of gears, and the rotation of the motor can be efficiently reduced and rotated.

  According to the electric power steering apparatus of the present invention, the driven gear is obtained by changing the amount of deformation of the elastic body provided at both ends of the pair of drive gears by the drive gear or by making the motor torque different. Is always in pressure contact with each drive gear, so that the driven gear can always be supported without backlash. For this reason, the electric power steering apparatus according to the present invention can improve the merchantability by eliminating the hitting sound caused by the tooth surface collision generated by the backlash between the driven gear and the drive gear. Further, in the present invention, since the conventional backlash adjustment is not required, it is possible to reduce the man-hours for adjustment work and the assembling time, so that the cost can be reduced.

First, an electric power steering apparatus according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is an explanatory diagram showing the overall structure of an electric power steering apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view in the direction of the arrow XX in FIG. 3 is a cross-sectional view in the YY line direction of FIG. FIG. 4 is a diagram showing the electric power steering apparatus according to the embodiment of the present invention, and is an enlarged exploded perspective view showing an assembled state of the elastic body. FIG. 5 is a diagram illustrating the electric power steering apparatus according to the embodiment of the present invention, and is an explanatory diagram illustrating a meshed state of the worm wheel and the worm.

  As shown in FIG. 1, the steering mechanism St is a device that steers the directions of the wheels W and W by rotating the steering handle 1. The steering mechanism St includes a steering handle 1, upper and lower steering shafts 2, 4, upper and lower universal joints 3, 5, a reducer case 6, a pinion shaft 7, a steering gear box 8, a rack bar. 18 and tie rods 9 and 9.

  The electric power steering device Ps is a device that rotates the first and second motors Ma and Mb with electricity from a battery (not shown) to generate thrust to assist and lighten the operation of the steering handle 1. The electric power steering device Ps includes a speed reducer case 6, first and second motors Ma and Mb, a steering torque sensor TS, and an electronic control unit U.

  The steering handle 1 is an operating body that is fixed to the upper end portion of the upper steering shaft 2 and is rotated by the operation of the driver. The upper steering shaft 2 is connected to a pinion shaft 7 protruding upward from the reduction gear case 6 via an upper universal joint 3, a lower steering shaft 4 and a lower universal joint 5.

A steering gear box 8 is connected to the lower end of the speed reducer case 6. Rack bars 18 extend in the direction of the wheels W and W from the left and right ends of the steering gear box 8, and tie rods are connected to both ends of the rack bar 18. 9, 9 is projected, and left and right wheels W, W are installed via a knuckle (not shown). The reduction gear case 6 supports the first motor Ma and the second motor Mb.
The first and second motors Ma and Mb are controlled by an electronic control unit U to which a signal from a steering torque sensor Ts provided in the speed reducer case 6 is input.

  As shown in FIG. 2, the reduction gear case 6 includes a lower case 10 that is integral with the steering gear box 8, an intermediate case 11 that is attached to the upper surface of the lower case 10 with bolts B <b> 1, and an upper surface of the intermediate case 11. And a motor case 44 and 45 (see FIG. 3) for fixing the first and second motors Ma and Mb to the speed reducer case 6. The speed reducer case 6 has a ball bearing 13 installed at the lower end of the lower case 10 and a ball bearing 14 installed at the upper end of the upper case 12, and the pinion shaft 7 is rotated by the ball bearings 13, 14. Supports freely.

The pinion shaft 7 has a worm wheel 15 fixed at the center, a steering torque sensor Ts for detecting the rotational torque of the steering handle 1 (see FIG. 1) installed at the upper end, and a rack 17 at the lower end. An intermeshing pinion 16 is provided.
The pinion shaft 7 corresponds to a “supported shaft of a driven gear” described in the claims.

As shown in FIG. 2, the rack 17 is formed directly on the rack bar 18. The rack bar 18 is supported inside the steering gear box 8 so as to be movable left and right.
The steering gear box 8 is formed with a lateral hole 8a for accommodating a pressing member 19 for pressing the rack bar 18 from the lateral direction so as to be able to advance and retract. In the lateral hole 8a, a pressing member 19 that is in contact with the back surface of the rack bar 18, a spring 20 for urging the pressing member 19 toward the pinion 16, and a spring receiver of the spring 20 and the lateral hole 8a are closed. A hollow bolt 21 that also serves as a member for this purpose is provided. The hollow bolt 21 is screwed into a screw portion formed in the opening 8b of the lateral hole 8a and is prevented from coming off by a set nut 22.
The rack 17 is pressed by the pressing member 19 urged by the spring 20 on the back surface of the rack bar 18, thereby eliminating the backlash at the position where the rack 17 meshes with the pinion 16.

  As shown in FIG. 3, the speed reducer case 6 is a case for housing the first and second worms 30, 31 and the worm wheel 15, and is made of metal or the like. The reduction gear case 6 is internally provided with first and second worms 30, 31 meshing with the worm wheel 15 at left and right symmetrical positions around the pinion shaft 7. Fixed to the left and right inner walls 6a, 6b of the speed reducer case 6 are ball bearings 26, 27 that support the first and second rotary shafts 24, 25 integrally formed with the first and second worms 30, 31. Has been. In addition, motor cases 44 and 45 holding the first motor Ma and the second motor Mb are fitted into the left and right openings 6c and 6d of the speed reducer case 6 via ball bearings 28 and 29, respectively. The motor cases 44 and 45 are fixed to the speed reducer case 6 by bolts B3 and B4, so that the ball bearings 26, 27, 28 and 29 and the first and second rotating shafts 24 and 25 are separated from the speed reducer case 6. Hold firmly so that it will not fall out.

The two first and second motors Ma and Mb are drive sources for rotating the steering handle 1 (see FIG. 1) via the first and second worms 30 and 31 and the worm wheel 15, and have the same torque. It consists of a motor of the same type. The first and second motors Ma and Mb are respectively arranged at symmetrical positions of the speed reducer case 6 with the worm wheel 15 as the center. The first and second motors Ma and Mb are provided with a first rotating shaft 24 and a second rotating shaft 25 that extend to each motor shaft (not shown). The first and second rotating shafts 24 and 25 are attached to the lower case 10 by ball bearings 26 and 27 installed at the front end portions and ball bearings 28 and 29 installed on the first and second motors Ma and Mb side. It is pivotally supported.
The first and second motors Ma and Mb correspond to “one set of motors” recited in the claims. The first and second motors Ma and Mb are not limited to two, and may be plural.

  As shown in FIG. 4, the first and second rotary shafts 24 and 25 are drive shafts that rotate together using the first and second motors Ma and Mb as drive sources, respectively. The first and second rotating shafts 24 and 25 are formed with first and second worms 30 and 31 at the center, and first and second rotations on both sides of the first and second worms 30 and 31, respectively. Large diameter portions 24a, 24b, 25a, 25b larger than the diameters of the shafts 24, 25 are formed. The small-diameter portions 24c, 24d, 25c, and 25d formed below the large-diameter portions 24a and 25a and above the large-diameter portions 24b and 25b have washer-like metal support rings 36, 37, 38, and 39, respectively. , 40, 41, 42, 43, ring-shaped elastic bodies 32, 33, 34, 35 and ball bearings 26, 27, 28, 29 are fitted.

The elastic bodies 32, 33, 34, and 35 are members that are installed at both ends of the first and second worms 30 and 31 and elastically support the first and second worms 30 and 31 by pressing them. The elastic body 32 installed on the distal end side of the first rotating shaft 24 is a second one of the second rotating shaft 25 that is located at an opposing position around the pinion shaft 7 (see FIG. 3) that supports the worm wheel 15. Compared to the elastic body 35 on the motor Mb side, the elastic body 35 is made of an elastic material such as soft soft synthetic rubber and has a large deformation amount (displacement amount).
The elastic body 34 installed on the first motor Ma side of the first rotating shaft 24 is located at the tip of the second rotating shaft 25 at the opposite position with the pinion shaft 7 that pivotally supports the worm wheel 15 as a center. Compared with a certain elastic body 33, it is made of an elastic material such as hard and relatively hard synthetic rubber, and is formed with a small deformation amount (displacement amount).
For this reason, the elastic force of the elastic bodies 32 and 33 is different from the elastic bodies 34 and 35 (refer FIG. 5).

  As shown in FIG. 4, on the upper and lower surfaces of the elastic bodies 32, 33, 34, 35, annular recesses 36a, 37a, formed in support rings 36, 37, 38, 39, 40, 41, 42, 43, respectively. Annular convex portions 32a, 32b, 33a, 33b, 34a, 34b, 35a, 35b that engage with 38a, 39a, 40a, 41a, 42a, 43a are formed.

  The elastic bodies 32, 33, 34, and 35 are not limited to ring-shaped synthetic rubber, but have elasticity that is installed on the first and second rotating shafts 24 and 25 and expands and contracts in the axial direction. I just need it. The elastic bodies 32, 33, 34, and 35 may be, for example, a coil spring, a spring washer, or an elastic synthetic resin.

  As shown in FIG. 3, the first and second worms 30, 31 are respectively meshed and installed on both sides in the diameter direction of a common worm wheel 15 fixed to the pinion shaft 7. The worm wheel 15 is a driven gear that meshes with the first and second worms 30 and 31, and the first and second motors Ma and Mb with the first and second worms 30 and 31. A gear transmission mechanism for decelerating high-speed rotation of the two rotary shafts 24 and 25 is configured.

  The first and second worms 30 and 31 correspond to “one set of drive gears” recited in the claims. The worm wheel 15 corresponds to a “driven gear” recited in the claims.

Next, the operation of the electric power steering apparatus according to the embodiment of the present invention will be described.
When the driver rotates the steering handle 1 shown in FIG. 1, the pinion shaft 7 rotates via the upper steering shaft 2, the upper universal joint 3, the lower steering shaft 4, and the lower universal joint 5. The rotation of the pinion shaft 7 is detected by the steering torque sensor Ts, and the detected steering torque signal is sent to the electronic control unit U. The electronic control unit U calculates currents for driving the first and second motors Ma and Mb, and sends drive currents to the first and second motors Ma and Mb for rotation.

  When the first and second motors Ma and Mb are driven, the worm wheel meshes with the first and second worms 30 and 31 formed on the first and second rotating shafts 24 and 25 as shown in FIG. Assist torque from the first and second motors Ma and Mb is transmitted to 15. As a result, the steering torque for rotating the steering handle 1 by the driver is assisted and can be operated lightly.

  The electric power steering device Ps can use a small motor as compared with the case of using one large motor by generating an assist torque by the two first and second motors Ma and Mb. Become. For this reason, the first and second motors Ma and Mb can reduce the load applied to the tooth surfaces of the first and second worms 30 and 31 and the worm wheel 15 by half by using a motor having a relatively small rotational torque. The durability of the gear mechanism can be improved.

  In addition, even if one of the first and second motors Ma and Mb fails, the other motor can assist, so that a complete failure of the assist force can be prevented.

  At this time, the first and second worms 30, 31 rotate and the tooth surfaces press the tooth surfaces of the worm wheel 15, thereby rotating the worm wheel 15. For this reason, the first and second worms 30 and 31 have an elastic body 32 that supports the first and second worms 30 and 31 with a reaction force proportional to the power of the first and second motors Ma and Mb. , 33, 34, 35.

When the first and second motors are stopped, the rotational torques of the first and second worms 30 and 31 become zero. Then, the elastic bodies 32, 33, 34, and 35 are released from their displacements and returned to their original positions.
For this reason, the residual torque in the direction of arrow C is applied to the elastic body 32 with respect to the first worm 30, and the residual torque in the direction of arrow D is applied to the elastic body 35 with respect to the second worm 31.

For example, if the deformation amount a of the elastic body 32 at this time is larger than the deformation amount b of the elastic body 35, the residual torque in the direction of arrow C of the first worm 30 by the elastic body 32 is The residual torque in the direction of arrow D is overcome and the worm wheel 15 is rotated slightly in the direction of arrow E.
Therefore, the tooth surface of the first worm 30 is always in pressure contact with the tooth surface of the worm wheel 15, and the tooth surface of the second worm 31 is also rotated by the rotation of the worm wheel 15 in the direction of arrow E. The backlash between the first and second worms 30 and 31 and the worm wheel 15 is eliminated.

Similarly, when the deformation amount c of the elastic body 33 is larger than the deformation amount d of the elastic body 34, the residual torque of the second worm 31 by the elastic body 33 overcomes the residual torque of the first worm 30 by the elastic body 34. The worm wheel 15 is slightly rotated in the direction of arrow F.
Therefore, the tooth surface of the second worm 31 is always in pressure contact with the tooth surface of the worm wheel 15, and the tooth surface of the first worm 30 is also rotated by the rotation of the worm wheel 15 in the direction of arrow F. The backlash between the first and second worms 30 and 31 and the worm wheel 15 is eliminated.

As described above, the worm wheel 15 is held by the holding force of the first and second worms 30 and 31 biased by the elastic bodies 32, 33, 34, and 35, so that the worm wheel 15 is vibrated by the road surface during traveling. It is possible to eliminate rattling between the worm wheel 15 and the first and second worms 30 and 31, and the tooth hitting sound caused thereby.
For this reason, the electric power steering device Ps is provided with the elastic bodies 32, 33, 34, and 35 having different deformation amounts a, b, c, and d, so that the conventional backlash adjustment work for reducing the hitting sound is performed. Can be abolished and the work process can be simplified.

  The present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the technical idea, and the present invention extends to these modifications and changes. Of course.

  FIG. 6 is a block diagram showing a modification of the electric power steering apparatus according to the embodiment of the present invention. FIG. 7 is a view showing a modification of the electric power steering apparatus according to the embodiment of the present invention, and is an explanatory view showing a meshed state of the worm wheel and the worm.

  The rattling prevention means of the worm wheel 15 and the first and second worms 30 and 31 is not limited to those by the elastic bodies 32, 33, 34 and 35 having different deformation amounts (see FIG. 5). 6 and 7, the rotational torques of the first motor Mc and the second motor Md may be different.

  Hereinafter, modified examples of the electric power steering apparatus according to the embodiment of the present invention will be described with reference to FIGS. In addition, the thing of the same structure as the said embodiment uses the same code | symbol, and abbreviate | omits the description.

As shown in FIG. 7, the first motor Mc and the second motor Md have different rotational torques T1 and T2, respectively. For example, the rotational torque T1 of the first motor Mc is large, and the rotational torque T2 of the second motor Md is small.
The elastic bodies 46, 47, 48, 49 installed at both ends of the first and second worms 30, 31 are, for example, synthetic rubber, synthetic resin, or spring members having the same shape and the same deformation amount (displacement amount). Consists of.

  As shown in FIG. 6, the steering torque sensor Ts is a detector for detecting the steering torque T, and is configured to send a signal of the steering torque T to the electronic control unit U. The electronic control unit U includes target motor drive current calculation means 50 and motor drive means for driving the first and second motors Mc and Md by the target motor drive currents D1 and D2 calculated by the target motor drive current calculation means 50, respectively. 51. The target motor drive current calculation means 50 calculates target motor drive currents D1 and D2 by map search using the steering torque T detected by the steering torque sensor Ts as a parameter. The motor drive means 51 performs feedback control so that the current supplied to the first and second motors Mc and Md matches the target motor drive currents D1 and D2.

In this way, when the rotational torque T1 of the first motor Mc is configured to be greater than the rotational torque T2 of the second motor Md, reaction forces e and f proportional to the rotational torques T1 and T2 respectively are elastic bodies 46, 47, and 48. , 49. The reaction force e of the elastic body 46 by the first motor Mc is larger than the reaction force f of the elastic body 49 by the second motor Md.
For this reason, the residual torque in the direction of arrow C of the first worm 30 by the elastic body 46 overcomes the residual torque in the direction of arrow D of the second worm 31 by the elastic body 49, and slightly lifts the worm wheel 15 in the direction of arrow E. Rotate.
Therefore, the tooth surface of the first worm 30 is always in pressure contact with the tooth surface of the worm wheel 15, and the tooth surface of the second worm 31 is also rotated by the rotation of the worm wheel 15 in the direction of arrow E. The backlash between the first and second worms 30 and 31 and the worm wheel 15 is eliminated.

  In this manner, the worm wheel 15 is traveling by being held by the holding force of the first and second worms 30 and 31 urged to the elastic bodies 46 and 49 by the first and second motors Mc and Md. It is possible to eliminate rattling between the worm wheel 15 and the first and second worms 30 and 31 due to vibration caused by the road surface and the like, and the sound of the tooth surface caused by this.

  The electric power steering apparatus according to the embodiment and the modification of the present invention described above includes, for example, first and second motors Ma, Mb, Mc, Md, and first and second worms 30, 31. However, they are not limited to two, and may be plural.

  In the embodiment and the modification of the present invention, the first and second worms 30 and 31 are used as drive gears and the worm wheel 15 is used as a driven gear. However, the drive gear may be a rack and the driven gear may be a pinion.

It is explanatory drawing which shows the whole structure of the electric power steering apparatus which concerns on embodiment of this invention. It is an arrow XX direction expanded sectional view of FIG. FIG. 3 is a cross-sectional view in the YY line direction of FIG. 2. It is a figure which shows the electric power steering apparatus which concerns on embodiment of this invention, and is an expansion exploded perspective view which shows the assembly | attachment state of an elastic body. It is a figure which shows the electric power steering apparatus which concerns on embodiment of this invention, and is explanatory drawing which shows the meshing state of a worm wheel and a worm. It is a block diagram which shows the modification of the electric power steering apparatus which concerns on embodiment of this invention. It is a figure which shows the modification of the electric power steering apparatus which concerns on embodiment of this invention, and is explanatory drawing which shows the meshing state of a worm wheel and a worm. It is explanatory drawing which shows the structure of the electric power steering apparatus which has two conventional motors.

Explanation of symbols

7 Pinion shaft (support shaft)
15 Worm wheel (driven gear)
30 1st worm (drive gear)
31 Second worm (drive gear)
32, 33, 34, 35, 46, 47, 48, 49 Elastic body a, b, c, d Deformation amount e, f Reaction force Ma, Mc First motor (motor)
Mb, Md Second motor (motor)
Ps Electric power steering device St Steering mechanism T1, T2 Torque

Claims (2)

A driven gear connected to the steering mechanism;
A set of drive gears meshed with and opposed to the driven gear;
Elastic bodies provided at both ends of the drive gear;
A set of motors for driving the drive gear;
An electric power steering apparatus comprising:
The electric power steering apparatus according to claim 1, wherein the elastic body has a different deformation amount of the elastic body disposed at an opposing position with a support shaft of the driven gear as a center. A driven gear connected to the steering mechanism;
A set of drive gears meshed with and opposed to the driven gear;
A set of motors for driving the drive gear;
An electric power steering apparatus comprising:
The electric power steering device, wherein the motors have different torques.

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