JP2000240747A - Electric rotary drive - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To realize a structure that is small and lightweight, has little backlash, and can obtain a large torque. SOLUTION: The output of an electric motor 5 is transmitted to a steering shaft 2 via a friction reducer 42 and a worm reducer 43 arranged in series with each other. Since the reduction ratio of the worm speed reducer 43 can be increased without increasing the backlash, the above problem can be solved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION An electric rotary drive device according to the present invention is incorporated in, for example, a steering device of an automobile and used as a power steering device for reducing a force required for a driver to operate a steering wheel. . Alternatively, it can be used as an actuator for operating an automobile brake, an actuator for switching a shift state of an automatic transmission for an automobile, and also as a starter (cell motor) for starting an engine.

[0002]

2. Description of the Related Art For example, as a device for reducing the force required for a driver to operate a steering wheel when giving a steering angle to a steering wheel (except for a special vehicle such as a forklift or the like, usually a front wheel). Power steering devices are widely used. Further, in such a power steering apparatus, an electric power steering apparatus using an electric motor as an auxiliary power source has begun to be widely used in recent years. The electric power steering device has advantages such as being smaller and lighter than the hydraulic power steering device, easily controlling the magnitude (torque) of the auxiliary power, and reducing the power loss of the engine. FIG. 5 schematically shows the basic configuration of such an electric power steering device.

The direction and magnitude of the torque applied to the steering shaft 2 from the steering wheel 1 are provided at an intermediate portion of the steering shaft 2 as a driven shaft, which is rotated based on the operation of the steering wheel 1 as an input unit. And a speed reducer 4 for detecting the torque. The output side of the speed reducer 4 is connected to an intermediate portion of the steering shaft 2, and the input side is connected to an output shaft of an electric motor 5 having a clutch. Further, the detection signal of the torque sensor 3 is, together with a signal indicating the vehicle speed,
It is input to a controller 6 for controlling the energization of the electric motor 5. Conventionally, as the speed reducer 4, a worm speed reducer having a large lead angle and having reversibility in the power transmission direction has been generally used. That is,
A worm wheel, which is a rotational force receiving member, is fixed to an intermediate portion of the steering shaft 2, and a worm, which is a rotational force applying member, is fixedly connected to an output shaft of the electric motor 5, and is engaged with the worm wheel. .

In order to impart a steering angle to the steered wheels, the steering wheel 1 is operated and the steering shaft 2 is operated.
Is rotated, the torque sensor 3 detects the rotation direction and the torque of the steering shaft 2 and sends a signal representing the detected value to the controller 6. Then this controller 6
Turns on the electric motor 5 to rotate the steering shaft 2 via the speed reducer 4 in the same direction as the rotation direction based on the steering wheel 1. As a result, the distal end (the lower end in FIG. 5) of the steering shaft 2 rotates with a torque larger than the torque based on the force applied from the steering wheel 1.

The rotation of the distal end of the steering shaft 2 is transmitted to the input shaft 10 of the steering gear 9 via the universal joints 7, 7 and the intermediate shaft 8. The input shaft 10 rotates a pinion 11 that constitutes the steering gear 9 and a tie rod 13 through a rack 12.
To give a desired steering angle to the steered wheels 14. As is apparent from the above description, the torque transmitted from the distal end of the steering shaft 2 to the intermediate shaft 8 via the universal joint 7 is transmitted from the steering wheel 1 to the base end of the steering shaft 2 (the upper end in FIG. 5). Part)
Is larger than the torque applied to the motor by the amount of the auxiliary power applied from the electric motor 5 via the speed reducer 4. Therefore, the force required for the driver to operate the steering wheel 1 in order to impart a steering angle to the steered wheels 14 can be reduced by the amount of the auxiliary power. The clutch attached to the electric motor 5 is disconnected when the electric motor 5 fails to rotate due to seizure or the like, and the steering shaft 2 cannot rotate due to the presence of the electric motor 5. It has the role of preventing it from becoming

As described above, in the case of the electric rotary drive device, conventionally, only a gear type speed reducer such as a worm speed reducer is used as the speed reducer 4 provided between the electric motor 5 and the steering shaft 2. I was That is, the electric motor 5 serving as an auxiliary power source for the power steering of the vehicle is 12
Since it is a DC electric motor of V or 24 V, it is difficult to obtain a necessary torque by the electric motor 5 alone. In addition, since an electric motor having a large torque increases both cost and weight, it is not preferable to use such an electric motor for a power steering device for an automobile in consideration of mass productivity.

In consideration of such circumstances, an electric rotary driving device for forming a power steering for an automobile includes a small-sized (for example, a yoke having a diameter of 100 mm or less) electric motor and a deceleration having a large reduction ratio. It is preferable to use it in combination with a machine. However, if an attempt is made to achieve the required reduction ratio by using only a gear-type reduction gear as the above-described reduction gear, noise, vibration, and the like are generated when the auxiliary power is applied, and the occupants including the driver feel uncomfortable. May be given. In addition, since there is an unavoidable backlash in the gear type speed reducer, the operability may be deteriorated, for example, the response may be slightly deteriorated. In particular, the backlash generated in the initial stage portion (the portion closer to the electric motor) of the speed reducer may cause play (rattle) in the rotational direction of the steering shaft 2 in an enlarged state. The deterioration is likely to be significant. These inconveniences can be solved to some extent by reducing the backlash or making the gears constituting the speed reducer made of synthetic resin. However, problems such as difficulty in managing the dimensional accuracy arise.

On the other hand, Japanese Patent Application Laid-Open No. H11-22799 discloses an electric rotary drive device for a power steering for an automobile, which combines a friction reduction device (traction drive reduction device) and a bevel gear type reduction device. Has been described.
In the case of the electric rotary drive described in this publication,
Compared with the conventional electric rotary drive device, the noise generated during operation can be reduced, and the operational feeling based on the reduction of backlash can be improved.

[0009]

In the case of the electric rotary drive described in the above-mentioned publication, a bevel gear type speed reducer is used as a gear type speed reducer combined with a friction speed reducer. It is difficult to realize an electric rotary drive device that is small and has a sufficient output torque. That is, in order to realize a large reduction ratio by the bevel gear type speed reducer, it is necessary to increase the diameter of the driven gear disposed on the output side, which makes it difficult to reduce the size. It is theoretically possible to achieve a large reduction ratio by reducing the diameter of the drive gear placed on the input side, but it is necessary to make the backlash extremely large in order to secure stable operation. Something is unrealistic.

In addition, studies have been made to use an electric actuator to perform the work of switching the shift state of an automobile brake or an automatic transmission for an automobile. It is necessary to minimize rattling based on rush and obtain a large torque. That is, the rattling based on the backlash leads to the deterioration of the positioning accuracy by the electric actuator, so that it is necessary to suppress it slightly. The present invention solves the above-mentioned problems of the conventional structure, can obtain a large output torque with a small size, can obtain a good operation feeling when incorporated in a power steering device or the like, and can be used as an actuator. The present invention has been invented in order to realize an electric rotary drive device capable of obtaining a high degree of positioning accuracy in such a case.

[0011]

SUMMARY OF THE INVENTION An electric rotary driving device according to the present invention comprises an electric motor, a driven shaft which is rotationally driven by an output shaft of the electric motor, and a drive shaft between the output shaft and the driven shaft. A friction reducer and a worm reducer arranged in series with each other; As the friction reducer, a wedge roller type described in, for example, the above-mentioned Japanese Patent Application Laid-Open No. 11-22799 can realize good transmission efficiency irrespective of the magnitude of the torque to be transmitted. From things
It can be used preferably. However, it is also possible to use a planetary roller type which has been described in Japanese Unexamined Patent Publication No. 47-26555 or the like and which has been widely known. Preferably, the friction reducer and the worm reducer are arranged in the order in which the friction reducer is arranged on the electric motor side and the worm reducer is arranged on the output shaft side. Then, the reduction ratio between the electric motor and the output shaft (the product of the reduction ratios of these two reduction gears)
Is preferably about 50 to 200.

[0012]

According to the present invention having the above-described configuration, it is possible to realize an electric rotary drive device which is small in size, can obtain a large output torque, and can minimize the deterioration of operation feeling due to backlash. Also, when an electric actuator is configured, a high degree of positioning accuracy can be obtained. For example, when configuring an electric vehicle power steering device, if the electric motor driven at 12 V or 24 V is to be of a practical size, the torque of this electric motor is 0.1 to 0.5 kgf · m, but the torque of the output shaft of the electric rotary drive can be increased to about 5 to 30 kgf · m by the torque increasing action of the friction reduction gear and the worm reduction gear.

[0013]

1 to 3 show a first embodiment of the present invention in which an electric rotary drive device of the present invention is used as an auxiliary power unit of an automobile power steering device. ing. An intermediate portion of the steering shaft 2 that rotates based on the operation of the steering wheel 1 (see FIG. 5, omitted in FIG. 1) is rotatably supported inside the housing 15. The housing 15
An electric motor 5 serving as an auxiliary power source and a speed reducer 4 a for reducing the rotational driving force of the electric motor 5 and transmitting the reduced rotational driving force to the steering shaft 2 are provided on the sides of the steering shaft 2. The reduction gear 4a includes a friction reduction gear 42 and a worm reduction gear 43 arranged in series from the electric motor 5 side.

Incorporating into the electric rotary drive of the present invention,
The speed reducer case 16 that constitutes the friction speed reducer 42 of the speed reducer 4 a is held and fixed inside a cylindrical holding portion 17 provided on the side of the housing 15. The reduction gear case 16 includes a bottomed cylindrical main body 18 and the main body 1.
8 to close the base opening. In the reduction gear case 16, an inner half (the left half in FIG. 1) of the center roller 20 is provided with a through hole 21 formed substantially in the center of the lid 19.
Inserted through. A portion existing on the outer peripheral surface of the center roller 20 and inside an outer ring 22 described later is defined as a first cylindrical surface 23. The through hole 21 is slightly displaced (biased) from the center axis of the inner peripheral surface of the main body 18.
Position. The center roller 20 is provided in the through hole 2.
1 is rotatably supported by a rolling bearing such as a deep-groove type ball bearing 24, and is provided between the input portion of the speed reducer 4a and the output shaft of the electric motor 5 by the electric motor 5. It is freely rotatable through the clutch 52.

Also, three pivots 25a and 25 are provided inside the speed reducer case 16 and around the center roller 20.
b and 25c are arranged in parallel with the center roller 20, respectively. That is, each of these pivots 25a, 25b, 25
One end of c (the right end in FIG. 1) is supported by the lid 19, and the other end (the left end in FIG. 1) is supported by the connecting plate 26. In addition, these three pivots 25a, 25b, 25c
One of the pivots 25 located at the upper center of FIGS.
As for a, both ends thereof are press-fitted and fixed or inserted almost without rattling into fitting holes formed in the lid 19 and the connecting plate 26. Therefore, the pivot 25a is not displaced in the circumferential direction or the diametric direction in the speed reducer case 16.

On the other hand, the remaining two pivots 25b and 25c located on the lower left and right sides of FIGS.
6 is slightly displaceable in the circumferential and diametric directions. For this reason, a portion of the lid 19 and a part of the connecting plate 26 which is aligned with both ends of the pivots 25b, 25c is larger than the outer diameter of the pivots 25b, 25c as shown in FIG. Forming support holes 27, 27 having an inner diameter;
The two pivots 25b, 25
c are loosely engaged at both ends. A guide roller 28 and a wedge roller 29a, 29b, each of which is an intermediate roller, are provided around the intermediate portion of each of the pivots 25a, 25b, 25c, respectively.
Rolling bearings such as 0, 30 or deep groove ball bearings
It is rotatably supported. The connecting plate 26 is a part of the inner surface of the lid 19 (the surface on the space side where the guide roller 28 and the wedge rollers 29a and 29b are installed, and the left surface in FIG. 1). A protruding portion 31 protruding from a position off the rollers 29a and 29b;
31 and is connected and fixed to the lid 19 by connecting bolts 32, 32.

A cylindrical outer ring 22 with a bottom is rotatably provided inside the speed reducer case 16 at a portion surrounding the guide roller 28 and the wedge rollers 29a and 29b. The outer ring 22 includes a cylindrical portion 33 and the cylindrical portion 3.
3 has a bottom plate portion 34 for closing one end (the left end in FIG. 1). The inner peripheral surface of the cylindrical portion 33 is a second cylindrical surface 35. And, this second cylindrical surface 35
And the guide roller 28 and the wedge roller 29a,
The third cylindrical surfaces 36, 36, which are the outer peripheral surfaces of 29b, can be freely contacted. Also, at the center of the outer surface of the bottom plate portion 34 constituting the outer ring 22 (the surface opposite to the space where the rollers 28, 29a, and 29b are present, the left surface in FIG. 1)
The base end (the right end in FIG. 1) of the output shaft 37 is connected and fixed. The output shaft 37 is rotatably supported by a rolling bearing such as a deep groove ball bearing 39 inside a second through hole 38 formed in the center of the main body 18 constituting the speed reducer case 16. I have.

The third cylindrical surface 3 which is the outer peripheral surface of the guide roller 28 and the wedge rollers 29a and 29b.
Reference numerals 6 and 36 denote a first cylindrical surface 23 which is an outer peripheral surface of the center roller 20 and a cylindrical portion 33 which constitutes the outer ring 22.
Is in contact with the second cylindrical surface 35, which is the inner peripheral surface of the second cylindrical surface. The center of the center roller 20 and the centers of the output shaft 37 and the outer ring 22 are eccentric to each other. That is, as described above, the through-hole 21 through which the center roller 20 is inserted is provided at a position slightly deviated from the center axis of the inner peripheral surface of the main body 18, while the output shaft 37 is inserted through the through-hole 21. The second through-hole 38 is provided at a portion corresponding to the central axis of the inner peripheral surface of the main body 18. The output shaft 37 rotatably supported inside the second through hole 38 and the outer ring 22 are concentric with each other. Therefore, the center roller 20, the outer ring 22, and the output shaft 37 are eccentric with respect to each other by a shift amount δ of the through hole 21 from the center of the speed reducer case 16. And
The guide roller 28 and the wedge roller 2 exist between a first cylindrical surface 23 which is an outer peripheral surface of the center roller 20 and a second cylindrical surface 35 which is an inner peripheral surface of the cylindrical portion 33.
The width dimension of the annular space 49 provided with 9a and 29b is not uniform in the circumferential direction by an amount corresponding to the eccentricity δ.

As described above, the outer diameters of the guide roller 28 and the wedge rollers 29a and 29b are made different from each other because the width of the annular space 49 is made uneven in the circumferential direction. That is, the diameters of the wedge rollers 29a and 29b located on the side where the center roller 20 is eccentric with respect to the outer ring 22 (the lower side in FIGS. 2 and 3) are the same and relatively small. On the other hand, the opposite side of the eccentricity of the center roller 20 with respect to the outer ring 22 (see FIGS.
The upper side of the guide roller 28 has a larger diameter than the two wedge rollers 29a and 29b. The guide roller 28 and the wedge roller 29
a, a third cylindrical surface 36, 36 which is an outer peripheral surface of 29b,
The first and second cylindrical surfaces 23 and 35 are in contact with each other.

Incidentally, of the one guide roller 28 and the two wedge rollers 29a, 29b, the pivot 25a supporting the guide roller 28 is fixed in the speed reducer case 16 as described above. . On the other hand, the pivots 25b, 25c supporting the wedge rollers 29a, 29b
As described above, a small displacement in the circumferential direction and the diametrical direction is freely supported in the speed reducer case 16 as described above. Therefore, the wedge rollers 29a and 29b also
Within the speed reducer case 16, it is slightly displaceable in the circumferential direction and the diametric direction. Each of the wedge rollers 2 is formed by an elastic material such as a compression coil spring 41, 41 mounted in a cylinder hole 40, 40 provided in the connecting plate 26.
The pivots 25b and 25c supporting the shafts 9a and 29b are elastically and lightly pressed to move the wedge rollers 29a and 29b rotatably supported by the pivots 25b and 25c toward a narrow portion of the annular space 49. are doing.

In order to transmit the rotation of the output shaft 37 of the friction reducer 42 constructed as described above to the steering shaft 2 at a further reduced speed, a portion located in the housing 15 at an intermediate portion of the steering shaft 2. The worm wheel 44 constituting the worm speed reducer 43 is externally fitted and fixed. The material of the worm 44 is not particularly limited, but is made of metal when strength is required, and is made of synthetic resin when quietness of the worm speed reducer 43 is particularly required. In this case, if high-performance resin such as polyacetal is used, both quietness and strength can be achieved at a high level. A worm 45 is rotatably supported inside the housing 15 by a pair of rolling bearings such as deep groove ball bearings 46, 46.
The material of the worm 45 is also considered in the same manner as the worm wheel 44. The central axis of the worm 45 and the central axis of the steering shaft 2 are in a torsional position. Also, the base end of the worm 45 (FIG. 1)
Of the output shaft 37 (left end of FIG. 1).
Means that the rotational force can be freely transmitted by a coupling of concave and convex engagement or the like. The worm wheel 44 and the worm 45 are meshed with each other with reversibility in the power transmission direction. Therefore, the output shaft 3
7, the rotation of the steering shaft 2 is reduced.
Is transmitted to

When the electric rotary drive device of the present invention configured as described above is used, that is, when the steering angle is given to the steered wheels 14 (see FIG. 5) based on the operation of the steering wheel 1, the steering shaft is used. The operation at the time of applying the auxiliary power by the electric motor 5 to 2 is as follows. When the steering shaft 2 is rotated by the steering wheel 1, the controller 6 (see FIG. 5) energizes the electric motor 5. The electromagnetic clutch 52 is provided between the output portion of the electric motor 5 and the center roller 20 as necessary. When such an electromagnetic clutch 52 is present, the electromagnetic motor 5 is energized. Then, the center roller 20 of the friction reducer 42 is rotated. The rotation of the center roller 20 is
A first cylindrical surface 23 which is an outer peripheral surface of
These guide rollers 28 and wedge rollers 29a, 29b are provided via respective inner diameter side contact portions 47, 47 which are contact portions with third cylindrical surfaces 36, 36 which are outer peripheral surfaces of the wedge rollers 29a, 29b. Transmitted to. Further, the rotation of the guide roller 28 and the wedge rollers 29a, 29b is caused by the rotation of the third cylindrical surfaces 36, 36 and the second cylindrical surface 35 provided on the inner peripheral surface of the cylindrical portion 33 constituting the outer ring 22. Through the outer diameter side contact portions 48, 48, which are the contact portions of
It is transmitted to this outer ring 22. Then, the output shaft 37 fixedly connected to the outer ring 22 rotates.

When the output shaft 37 rotates in this manner, the worm 45 rotates, and the worm 45 further drives the worm wheel 44 fixed to the outer peripheral surface of the intermediate portion of the steering shaft 2 to rotate the worm 45. The auxiliary power in the rotation direction is applied to the shaft 2. The turning force applied to the steering shaft 2 from the steering wheel 1 and the electric motor 5 in this manner is transmitted to the steering gear 9 via the universal joints 7 and 7 and the intermediate shaft 8.
The rack 12 is displaced in the axial direction via the pinion 11 to impart a desired steering angle to the steered wheels 14 (see FIG. 5). For this reason, the steering wheel 1 is provided to provide a steering angle to the steered wheels 14 by the amount of the auxiliary power applied to the steering shaft 2 from the electric motor 4.
The force required to operate the device can be reduced. Note that the magnitude (torque) of the auxiliary power applied from the electric motor 5 to the steering shaft 2 changes according to the vehicle speed, the engine speed, and the like. That is, the controller 6 increases the amount of power to the electric motor 5 and increases the auxiliary power as the vehicle speed decreases (or the engine speed decreases).
The force required to operate the steering wheel 1 is reduced.

At the time of applying the auxiliary power as described above, the center roller 20 constituting the friction reducer 42 is, for example, shown in FIGS.
When the outer ring 22 rotates in the clockwise (or counterclockwise) direction in the same manner as above, respectively, the outer ring 22 is rotatably supported on the right pivot 25b (or the left pivot 25c) in FIGS. Wedge roller 29a (or 29
b) in the annular space 49 existing between the first and second cylindrical surfaces 23 and 35 toward the narrow portion (the lower central portion in FIGS. 2 and 3) of the annular space 49. Moving. As a result, the third cylindrical surface 36, which is the outer peripheral surface of the wedge roller 29a (or 29b) rotatably supported on the pivot 25b (or 25c), is connected to the first cylindrical surface 23 and the second cylindrical surface 35. Press strongly. Then, the third cylindrical surface 36 related to the wedge roller 29a (or 29b)
And an inner diameter side contact portion 47 which is a contact portion between the first cylindrical surface 23 and the wedge roller 29a (or 29b).
The contact pressure of the outer diameter side contact portion 48, which is the contact portion between the third cylindrical surface 36 and the second cylindrical surface 35, becomes high.

The one wedge roller 29a (or 2)
When the contact pressure between the inner and outer contact portions 47 and 48 with respect to 9b) increases, at least one of the center roller 20 and the outer ring 22 causes an assembling gap or elastic deformation. A slight displacement along the respective diametrical direction. As a result, the remaining two intermediate rollers, the guide roller 28 and the wedge roller 29b (or 29a)
And two inner-diameter-side abutting portions 47, 47, which are abutting portions of the third cylindrical surfaces 36, 36, which are the outer peripheral surfaces of the central roller 20, and the first cylindrical surface 23, which is the outer peripheral surface of the center roller 20, Outer two portions which are contact portions between the third cylindrical surfaces 36, 36 which are the outer peripheral surfaces of the wedge roller 29b (or 29a) and the guide roller 28 and the second cylindrical surface 35 which is the inner peripheral surface of the outer ring 22. The contact pressure of the radial contact portions 48 increases.

A wedge roller 29a (or 29b) rotatably supported by the one pivot 25b (or 25c).
Of the center roller 2 in the annular space 49 toward the narrow portion of the annular space 49.
It changes from 0 in accordance with the magnitude of the torque transmitted to the outer ring 22. That is, as the driving torque of the center roller 20 by the electric motor 5 increases, the force for moving the wedge roller 29a (or 29b) toward the narrow portion of the annular space 49 increases. The greater the force, the greater the contact pressure between the inner and outer diameter contact portions 47, 48. Conversely, when the driving torque is small, the contact pressures of the inner and outer contact portions 47 and 48 are small. In order to ensure the transmission efficiency of the friction reducer 42, the contact portions 47, 4
In order to prevent the occurrence of slippage at step 8, it is necessary to increase the contact pressure of these contact portions in accordance with the torque to be transmitted.

On the other hand, if the contact pressure is kept high even when the torque to be transmitted is small, the rolling resistance at each of the contact portions 47 and 48 increases, and the friction reducer 42 Deteriorates transmission efficiency. On the other hand, when the torque to be transmitted is small, the friction reduction device 42 constituting the electric rotary drive device of the present invention, when the torque to be transmitted is small, applies the contact pressure between the inner and outer diameter contact portions 47 and 48. When the torque to be transmitted is large, on the contrary, the contact pressures of the inner and outer contact portions 47 and 48 are increased. Accordingly, regardless of the torque fluctuation of the auxiliary power based on the difference in the amount of power supply to the electric motor 5, the transmission efficiency of the friction reducer 42 is always kept good, and the battery for supplying power to the electric motor 5 is charged. The wear can be prevented.

As described above, in the case of the electric rotary drive device of the present embodiment, since the wedge roller type friction reduction device 42 is used in the front stage of the reduction device 4a, noise and noise during operation are reduced. Vibration does not occur and there is no backlash that affects the feeling of operation. For this reason, when used in a power steering device for an automobile, the occupant, including the driver, is not discomforted when the steering angle is given, and the operation feeling of the steering wheel 1 is not deteriorated. In addition, the power consumption can be reduced and the burden on the battery can be reduced. The meshing portion between the worm 45 and the worm wheel 44 that transmits the rotation of the output shaft 37 of the friction reducer 42 to the steering shaft 2 includes:
Although there may be some backlash, the backlash in this portion is not enlarged and the steering shaft 2 does not play. Therefore, these worms 4
5 and the presence of the meshing portion of the worm wheel 44,
Responsiveness does not deteriorate as much as discomfort is given to the driver.
Further, since the worm speed reducer 43, which is small and can increase the reduction ratio, is used as the gear type speed reducer constituting the speed reducer 4a together with the friction speed reducer 42, the electric motor 5 is particularly large. , The torque applied from the electric motor 5 to the steering shaft 2 can be made sufficiently large. Therefore, the steering force of a heavy automobile can be sufficiently reduced.

In the illustrated example, the electric rotary drive of the present invention is used as an auxiliary power source for a power steering device.
Has a pair of wedge rollers 29a and 29b,
It incorporates a device that can transmit rotational motion in both directions.
On the other hand, if the electric rotary drive device is used for applications where the torque transmission direction is limited to one direction, only one wedge roller is used and the torque transmission direction is limited to one direction. You may.

FIG. 4 shows a second embodiment of the present invention.
An example is shown. In the case of the present example, a planetary roller type is used as the friction reduction device 42a constituting the reduction device 4b. Therefore, in the case of this example, the worm 45 constituting the worm speed reducer 43 is arranged concentrically with the carrier 50 constituting the above-mentioned friction reducer 42a, and each planetary roller 5
By taking out the orbital motions of the carrier 50, the carrier 50
Rotate with. Since the configuration and operation of such a planetary roller type friction reducer are widely known in the related art, detailed illustration and description are omitted.

In practicing the present invention, for example, a one-way clutch or an electromagnetic clutch is connected in series between the output portion of the electric motor 5 and a driven rotary shaft such as the steering shaft 2 with respect to the direction of transmitting the rotational force. In some cases. In this case, the electromagnetic clutch may be provided in any part,
The one-way clutch is preferably provided on a driven rotation shaft having a low rotation speed. Further, when used in a power steering device, it is necessary to use a worm speed reducer having reversibility in the power transmission direction so that the steering shaft can be rotated even when the electric motor fails.
On the other hand, when the worm speed reducer is used for another purpose, a worm speed reducer whose power transmission direction is limited may be used.

[0032]

The electric rotary drive device of the present invention is constructed and operates as described above. However, despite its small size and light weight, for example, when it is used as a power steering device, it produces noise during operation. There is no vibration and no large backlash. Therefore, the electric power steering device can be assembled into a luxury car without giving a passenger or driver an uncomfortable feeling when the steering angle is given, and without deteriorating the operational feeling of the steering wheel. In addition, when an electric actuator is configured, a high degree of positioning accuracy can be obtained, which can contribute to an expanded use of the electric rotary drive device. Further, when used as a starter for starting the engine, noise during operation of the starter can be reduced.

[Brief description of the drawings]

FIG. 1 is a partially cutaway view showing a first example of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is an essential part perspective view showing a second example of the embodiment of the present invention.

FIG. 5 is a schematic diagram showing the entire structure of an electric power steering device, which is an example of a device for assembling the electric rotary drive device to which the present invention is applied.

[Explanation of symbols]

 Reference Signs List 1 steering wheel 2 steering shaft 3 torque sensor 4, 4a, 4b reduction gear 5 electric motor 6 controller 7 universal joint 8 intermediate shaft 9 steering gear 10 input shaft 11 pinion 12 rack 13 tie rod 14 steering wheel 15 housing 16 reduction gear case 17 Holder 18 Main body 19 Lid 20 Center roller 21 Through hole 22 Outer ring 23 First cylindrical surface 24 Ball bearing 25a, 25b, 25c Pivot shaft 26 Connecting plate 27 Support hole 28 Guide roller 29a, 29b Wedge roller 30 Radial needle bearing 31 Protrusion Part 32 Connection bolt 33 Cylindrical part 34 Bottom plate part 35 Second cylindrical surface 36 Third cylindrical surface 37 Output shaft 38 Second through hole 39 Ball bearing 40 Cylinder hole 41 Compression coil spring 42, 42a Friction reducer 43 Worm reduction Machine 44 c Muhoiru 45 worm 46 ball bearing 47 the inner diameter side abutment portion 48 the outer diameter side contact portion 49 an annular space 50 carrier 51 planetary rollers 52 electromagnetic clutch

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Ito 1-50, Kumeinuma Shinmei 1-chome, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (reference) 3J009 DA11 DA17 ED06 ED08 FA08 FA10 3J051 AA01 BA03 BB08 BC03 BD02 BE02 ED15 FA02

Claims (1)

[Claims] An electric motor, a driven shaft that is rotationally driven by an output shaft of the electric motor, and a friction reduction device and a worm reduction device that are arranged in series between the output shaft and the driven shaft. An electric rotary drive device comprising: