JP2002195309A - Transmission mechanism for motor-driven power steering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To install a clutch in a power transmission mechanism for a power assist in motor-driven power steering and to carry out secure steering capable of being realized with simple work for mounting a structure and a device thereof. SOLUTION: This transmission mechanism comprises a steering shaft member 1, a clutch A engaged with and connected to the steering shaft member 1 by the rotative motion of an outer ring member 6 mounted at its radial circumference position between two disc-like cover materials 2, 2 mounted to the steering shaft member 1 by being axially appropriately spaced, a worm wheel 15 mounted in the circumference of the outer ring member 6, a worm 16 gearing with the worm wheel 15, a motor 17 for rotating the worm 16, and a sensor 18 for sensing the torsion of the steering shaft member 1 to drive the motor 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering system in which a clutch is provided in a power transmission mechanism of a power assist. The present invention relates to a transmission mechanism of an electric power steering that can be performed.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 9-20256 discloses an electric power steering apparatus having a torque limiter mechanism for coping with excessive torque acting on a steering shaft. This torque limiter mechanism is configured as a speed reducer composed of a worm wheel gear provided between a steering shaft and a motor that applies assist torque.

[0003] Specifically, the steering shaft and the worm wheel are connected by interposing a torque limiter mechanism (member) between the worm wheel of the reduction gear and the steering shaft. This torque limiter mechanism has a torque setting member that is radially deformed by being sandwiched between the outer periphery of the steering shaft and the inner periphery of the worm wheel.

The torque setting member is formed by integrally forming a plurality of semi-cylindrical projections projecting radially outward at regular intervals along a circumferential direction on a metal ring main body having a split groove. ing. The torque setting section is fitted between the steering shaft and the worm wheel both inside and outside. That is, the clutch comes into frictional contact.

[0005]

The conventional torque limiter is a mechanism in which a torque setting member having a metal ring main body having a protrusion formed at regular intervals is provided between a worm wheel and a steering shaft in a speed reducer. However, such a torque limiter has a simple structure and can reduce the number of parts and the number of processing steps. The torque limiter mechanism between the steering shaft and the worm wheel
If the rotation of the motor output shaft or the rotation of the worm wheel is locked for some reason, such as an external factor, the torque limiter mechanism acts to cause relative slip between the steering shaft and the worm wheel. Then, the steering shaft and the worm wheel have a function of rotating relative to each other so that the steering wheel can be steered.

However, in the relative sliding operation between the steering shaft and the worm wheel, frictional resistance is generated between the torque setting member and the worm wheel, or between the torque setting member and the steering shaft. For this reason, the rotation of the output shaft of the motor and the steering of the steering wheel when the rotation of the worm wheel is locked must be steered against the frictional resistance, and a considerable force is required. It is not easy.

In order to improve the steering in such a state, if the above-mentioned frictional resistance is set to be small, the torque of the transmission path for transmitting the output of the motor to the steering shaft via the worm wheel is set. Since the function (slip) of the limiter mechanism is easily operated, it is difficult to stably transmit the output of the motor as an assist force to the steering shaft, resulting in a structure lacking reliability. An object of the present invention is to reduce the frictional resistance between the steering shaft and the clutch and perform a reliable clutch operation.

[0008]

The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have found that the present invention provides a steering shaft member and an appropriate distance between the steering shaft member in the axial direction. A clutch that engages with and connects to the steering shaft member by a rotation operation of an outer ring member provided at a radially outer peripheral portion between the two disk-shaped cover members mounted in the outer ring member; An electric power steering transmission mechanism including a worm wheel provided on an outer periphery, a worm meshing with the worm wheel, a motor for rotating the worm, and a sensor for detecting the torsion of the steering shaft member and driving the motor. As a result, in the electric power steering, the assembling work of the structure and the device can be performed easily and the steering can be reliably performed. Those were.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. First, the present invention comprises a steering shaft of a steering shaft member 1, a clutch A, a worm wheel 15, a worm 16, a motor 17, and a sensor 18 (see FIG. 1). The steering shaft member 1 is provided with a gear reducer for assisting transmission of the rotational force of a motor 17 to the worm wheel 15 and the worm 1.
6 (see FIG. 2). The worm wheel is connected to the steering shaft member 1 via a one-way two-way clutch A.

The mechanism for detecting the rotational torque acting on the steering shaft member 1 has the following configuration. That is, the steering shaft member 1 is divided into an input shaft 1a side, an output shaft 1b side, and a region of the torsion bar 1c located between the input shaft 1a side and the output shaft 1b side. During steering, a rotational torque is applied to the steering shaft member 1 and the torsion bar 1
The input shaft 1a side and the output shaft 1 due to the twist of c
The difference in rotation between the b-side and the b-side is detected by the sensor 18 as an electric signal.

Secondly, a magnetic material or a diamagnetic material is provided partially without dividing the steering shaft member 1 into the above-described regions, and the stress applied when the steering shaft member 1 is twisted is rotated. There is a case where a so-called magnetostrictive torque sensor is electrically detected as a torque.

The electric signals of the sensor 18 for detecting the rotational torque of the steering shaft member 1 are indicated by E (not shown).
The motor 1 is sent to a CU (Electronic Control Unit) and is appropriately set with respect to the rotational torque of the steering shaft member 1.
The ECU wherein an assist torque of 7 is applied.
A control signal is sent to the motor 17 to rotate the motor 17, and the rotational force of the motor 17 is transmitted to the reduction gears of the worm 16 and the worm wheel 15.

The rotation is transmitted to the outer ring member 6 of the one-way two-way type clutch A connected to the speed reducer,
Depending on the rotation direction of the outer ring member 6, the sprags 3, 3,... Alternatively, the structure is such that the clutch A is engaged with the steering shaft member 1 by the wedge-shaped engagement of the roller-shaped engagement body 12, and the assist torque of the motor 17 is transmitted to the steering shaft member 1.

In this structure, the one-way two-way clutch A is connected to the steering shaft member 1 to assist the power as the motor 17 rotates. In addition, the motor 17 does not rotate, that is, a state in which so-called power assist is not required, or the motor 17 or the worm wheel 1 is not rotated.
5, when the speed reducer is locked by the worm 16, the clutch A is not connected to the steering shaft member 1. That is, even if the assist device is locked or inoperable for some reason,
Steering performance similar to that of manual steering can always be ensured without applying large frictional resistance during steering of the steering shaft member 1.

Next, the clutch A will be described.
The clutch A has a plurality of embodiments. The configuration of the first embodiment is shown in FIGS. 3 to 7, and mainly includes a disc-shaped cover member 2, a sprag 3, a holding member 4, an elastic member 5, an outer ring member 6, and the like. The disc-shaped cover member 2 is formed in a disc shape (including a substantially disc shape), and a through hole 2a is formed in the center thereof (see FIG. 4).

The disk-shaped cover member 2 is provided in two pieces,
The steering shaft member 1 is mounted so as to be immovable in the axial direction of the steering shaft member 1 at a predetermined interval along the axial direction of the steering shaft member 1 (see FIG. 4). The disc-shaped cover material 2,
2 may be directly rotatably mounted on the steering shaft member 1, or may be mounted using a locking member 7 such as a circlip or caulking. In the embodiment in which the locking member 7 is used, the disk-shaped cover members 2 may be slidable in the circumferential direction of the steering shaft member 1.

When the locking member 7 and the disk-shaped cover members 2 and 2 are slidable, the disk-shaped cover members 2 and 2
The steering shaft member 1 and the steering shaft member 1 are in a non-contact state by providing a gap, or are in a sliding state even when the disc-shaped cover members 2 and 2 contact the steering shaft member 1 shaft. Further, the disk-shaped cover members 2 and 2 and the steering shaft member 1
Between the disk-shaped cover members 2, 2 and the steering shaft member 1 so that rotation is not transmitted between the disk-shaped cover members 2, 2 and the steering shaft member 1. Some embodiments are held at 1.

The sprags 3, 3,... Are mounted between the disc-shaped cover members 2, 2 via a holding member 4 and an elastic member 5 (see FIG. 3). An outer ring member 6 is provided at an outer peripheral portion of the disc-shaped cover members 2, 2, and the sprag 3, the holding member 4, the elastic member 5, and the outer ring member 6
All are configured to be slidable in the rotational direction with respect to the disk-shaped cover members 2 and 2.

The sprags 3 are arranged at equal intervals (including substantially equal intervals) between the two disk-shaped cover members 2 and 2 and on the outer peripheral side surface of the steering shaft member 1. In the embodiment, three sprags 3, 3,... Are used, but the number of the sprags 3, 3,... Is not limited to the above, and more sprags 3, 3,. It is preferable that the sprags 3, 3,... Can be pressed against the steering shaft member 1 in a well-balanced manner (see FIG. 1).

The sprags 3, 3,... Are held between the two disk-shaped cover members 2, 2 via the holding member 4 so as to be tiltable within an appropriate tilt range. Here, the tilting of the sprags 3 means that the sprags 3 perform an operation of tilting to an arbitrary portion around any portion (see FIGS. 5 and 6 and the like). The tilting of the sprags 3 is performed between the disk-shaped cover members 2 and 2 on a plane orthogonal to the axial direction of the steering shaft member 1 (see FIG. 5).

The holding member 4 is arranged in a substantially annular shape with an appropriate gap from the outer peripheral side surface of the steering shaft member 1, and has a play insertion hole 4a through which each sprag 3 can be loosely inserted. The sprag 3 is disposed in the play insertion hole 4a so as to be tiltable. Further, the holding member 4 and the steering shaft member 1
And each of the play insertion holes 4a, 4
Elastic members 5 are arranged adjacent to the sprags 3, 3, ... which are loosely inserted in a, ... (see Fig. 3).

That is, the elastic member 5 is arranged between the sprags 3, 3,... Arranged at regular intervals around the shaft circumference of the steering shaft member 1, and any sprag 3 is elastically moved from both left and right sides thereof. It is pressed by the members 5 and 5 and is always held resiliently so as to maintain a neutral position which does not tilt to any side. As the elastic member 5, a coil spring is usually used, but the shape and structure of the elastic member 5 are not limited as long as the sprags 3 can be maintained in a neutral state. The neutral position of the sprag 3 described above is a state in which an extension of the neutral shaft of the sprag 3 is located at the center of the steering shaft member 1 (including a state in which the sprag 3 is approximately close) [FIG. (A)
reference〕.

The sprag 3 has a shaft side engaging portion 3a and an outer ring side engaging portion 3b formed on opposite sides [FIG.
(See (A) and (B).) The outer peripheral side surface of the steering shaft member 1 is an engaging surface with which a shaft-side engaging portion 3a of the sprag 3 engages in a wedge shape. When the sprags 3 tilt, the shaft-side engaging portion 3a comes into contact with the outer periphery of the steering shaft member 1 to be in a biting state, and the rotational force of the outer ring member 6 can be transmitted to the steering shaft member 1.

When the outer ring member 6 cannot rotate, the clutch does not hinder the rotation of the steering shaft member 1 as in the stationary state. The outer ring side engaging portion 3b of the sprag 3 is a portion that engages with a meshing engagement surface that causes the sprag 3 to tilt when the outer ring member 6 starts rotating. A formed tooth-shaped engagement surface is formed (see FIGS. 6A and 6B).
Further, as a modified example of the first embodiment, there is a sprag 3 and an inner peripheral engagement surface 6b which are simply formed by an uneven engagement structure. FIGS. 7A and 7B show a configuration in which the outer ring side engaging surface 3b of the sprag 3 has a convex shape and the inner peripheral engaging surface 6b of the outer ring member 6 has a concave engaging portion. FIG.
(C) and (D) show that the outer ring side engaging surface 3b of the sprag 3 has a concave shape, and the inner peripheral engaging surface 6b of the outer ring member 6 has a convex engaging portion.

The outer ring member 6 is rotatably mounted between the two disk-shaped cover members 2 and 2 and at an outer peripheral portion. The outer ring member 6 has an annular shape, and a driven surface 6 a to which rotational motion is transmitted from an external power source is formed on an outer peripheral side, and an outer ring side engaging portion 3 of the sprag 3 is formed on an inner peripheral surface.
b is formed with an inner peripheral engagement surface 6b. The driven surface 6a is a portion to which the worm wheel 15 is attached and to which rotation from the motor 17 is transmitted. Further, the driven surface 6a can be formed directly as a worm wheel. That is, the worm wheel 15 may be formed integrally with the clutch A.

The inner peripheral engaging surface 6b has an internal gear shape so that it can engage with the outer ring side engaging portion 3b of the sprag 3. Outer ring member 6
Are guided on the outer peripheral edge of the disc-shaped cover members 2, 2 on both side surfaces of the outer ring member 6 so that the disc-shaped cover members 2, 2 can be smoothly rotated between the disc-shaped cover members 2, 2. A part may be formed.

The clutch A is connected and disconnected by the rotation of the outer ring member 6 rotatably mounted on the clutch A. Since such a clutch A is used as an auxiliary force transmission device of an electric power steering device, the steering shaft member 1 and the clutch A can be easily manufactured without complicated assembly. Thus, the reliability of the clutch mechanism can be improved.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the disc-shaped cover members 2 and 2 are substantially the same as those in the first embodiment, and the disc-shaped cover members 2 and 2 are attached to the steering shaft member 1 via a locking member 7. Are slidably mounted. The sprags 3 in the second embodiment are independently pivotally supported by the one disk-shaped cover member 2 and the other disk-shaped cover member 2 at different positions in the radial direction (FIGS. 8 and 9). 9). Each sprag 3 can be appropriately tilted by the rotation difference between the rotations of the disk-shaped cover members 2 and 2 (see FIG. 10).

As a pivotal structure between the two disk-shaped cover members 2 and 2 and the sprags 3, the sprags 3
2 is pivotally supported at pivot portions P ₁ and P ₂ [see FIGS. 8 and 9A]. Specifically, the disc-shaped cover member 2 on one side and the sprag 3 are rotatably supported via a pin member 8a, and the same sprag 3 as the disc-shaped cover member 2 on the other side is connected to the pin. It is pivotally supported at a position radially different from the member 8a via a pin member 8b. The sprag 3 has a pivot hole through which the pin members 8a and 8b are inserted. Then, both disc-shaped cover members 2, 2
The sprags 3 are tilted due to a rotational displacement when the slewing rotates (see FIGS. 9A and 9B).

In order to incline the sprags 3 between the disc-shaped cover members 2 and 2, the pin members 8a and 8b
Either of them is in the loose insertion state (see FIG. 9B).
Preferably, one of the pin members 8a and 8b is pivotally supported at a substantially central position of a neutral axis of the sprag 3. Further, there is an embodiment in which the sprag 3 and the pin members 8a and 8b are integrally formed (see FIG. 9C). The sprag 3 is normally in a neutral state,
The shaft side engaging portion 3a and the outer peripheral side portion of the steering shaft member 1 are slidable even in a non-contact state or a contact state.

The sprags 3 and the outer ring member 6 are normally
It is stationary. The sprag 3 and the outer race member 6 are connected to either one of the two disk-shaped cover members 2 and 2 by a connecting pin member 8c [FIGS. 9A and 9B,
(C)). The sprag 3 and the inner periphery of the outer race member 6 are in a non-contact state. On the side of the steering shaft member 1 of the sprag 3, there is formed a shaft side engaging portion 3a which engages in a wedge shape and bites on the outer periphery of the steering shaft member 1.
On the outer ring member 6 side of the sprag 3, an outer ring side engaging portion 3b which bites and engages with the inner peripheral surface of the outer ring member 6 is formed.

Next, when power assist is applied at the time of steering, the outer ring member 6 rotates via a motor 17, a worm 16 and a worm wheel 15, and a disk connected to the outer ring member 6 on one side. The cover member 2 rotates together with the outer ring member 6 and the disk cover member 2 on the other side rotates. Therefore, between the two disk-shaped cover members 2, 2,
The sprags 3 pivotally supported via the pivot portions P ₁ and P ₂ at the locations are tilted, and the outer ring side engaging portion 3b of the sprag 3 engages with the inner peripheral engaging surface 6b of the outer ring member 6, and The shaft-side engaging portion 3a of the sprag 3 engages with the steering shaft member 1 (see FIG. 10).

As a result, the steering shaft member 1 and the outer ring member 6 are in a state where rotation can be transmitted through the sprags 3, 3,. When the outer ring member 6 is locked, the clutch A is in the same state as the stationary state, and the steering shaft member 1 and the clutch A do not hinder the rotation of the steering shaft member 1 in a non-contact or sliding state.

As a modified example of the second embodiment,
The sprag 3 is pivotally supported on the disc-shaped covering material 2 either side at one pivot P _3. That sprag 3
Outer ring side engagement portion 3b and inner peripheral engagement surface 6b of outer ring member 6
Are formed in mutually uneven shapes. The inner peripheral engaging surface 6b of the outer ring member 6 with respect to the rotation of the outer ring member 6
And the outer ring side engaging portion 3b of the sprag 3 engages, the sprag 3 tilts, and the steering shaft member 1 and the outer ring member 6
Are in a state where rotation can be transmitted via the sprags 3. FIGS. 11A and 11B show the outer ring side engagement surface 3 b of the sprag 3.
Are convex, and the inner peripheral engaging surface 6b of the outer ring member 6 is a concave engaging portion. FIG. 11 (C),
(D) is that the outer ring side engaging surface 3b of the sprag 3 is formed in a concave shape, and the inner peripheral engaging surface 6b of the outer ring member 6 is formed as a convex engaging portion.

Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, as in the first and second embodiments, the steering shaft member 1 is provided with two disk-shaped cover members 2 and 2. A cylindrical inner race member 10 is press-fitted into the outer periphery of the steering shaft member 1 (see FIG. 12). The inner ring member 10
A bush 11 is loosely inserted around the outside. The bush 11 has an annular shape, and the inner diameter of the bush 11 is
It is formed slightly larger than the outer diameter of the inner ring member 10. A plurality of roller-shaped engaging bodies 12 are arranged between the bush 11 and the outer ring member 6. The roller-shaped engaging body 12
Is composed of two roller-shaped members 12a, 12a and a resilient member 12b for repelling the roller-shaped members 12a, 12a mutually. The roller-shaped members 12a, 12a
The configuration is such that the two make a pair (FIG. 12).
Or see FIG. 14).

The shape of the inner peripheral engaging surface 6b of the outer ring member 6 is substantially polygonal, and one side of the outer ring member 6 is flattened so that a substantially central portion becomes higher toward the radial center of the outer ring member 6. It is formed in a convex shape (see FIGS. 15A and 15B). The roller-shaped engaging body 1 is formed by the inner circumferential engaging surface 6b.
Either of the two roller-shaped members 12a, 12a is in a wedge-shaped engagement in the space with the bush 11, is pressed toward the bush 11, and the roller-shaped member 12a and the bush 11
The rotation of the outer race member 6 and the inner race member 10 can be transmitted through the above.

FIG. 15A shows that when the outer ring member 6 rotates counterclockwise, the right roller-shaped member 12a engages in a wedge shape, and a pressing force F is applied to the bush 11 and the inner peripheral engaging surface 6b. Indicates that the player is wearing the phone. FIG. 15B shows that when the outer ring member 6 rotates clockwise, the left roller-shaped member 12a engages in a wedge shape, and the bush 11 and the inner peripheral engaging surface 6a.
The state where the pressing force F is applied to b is shown. Further, in the pair of roller members 12a, 12a, the other roller member 1
2a is in the opposite direction to the wedge-shaped engagement position, is located in a large space, and does not engage with the outer ring member 6 in a wedge-shaped manner.

When the outer ring member 6 is locked and cannot rotate, the outer ring member 6 and the roller-shaped engaging body 12 are in a stationary state, and the inner ring member 10 and the bush 11
And the rotation of the steering shaft member 1 is not hindered. There is also an embodiment in which the bush 11 is provided with a cut-out opening member in accordance with the wedge-shaped engagement of the roller-shaped engaging body 12, and the roller-shaped engaging body 12 is directly engaged with the inner ring member 10. The bush 11 is formed of a thin, flexible material, and engages with the inner ring member 10. In the third embodiment, there is an example in which the bush 11 is loosely inserted into the outer peripheral surface of the inner race member 10. In the above embodiment, when the clutch A and the steering shaft do not act on the power assist, the steering shaft member 1 inside the clutch A is in non-contact or slidable state with the clutch A. Only rotates alone,
The clutch A is not operated from the steering shaft member 1 side. In that case, the outer ring member 6 and the sprag 3
Alternatively, since the roller-shaped engagement body 12 is in a stationary state, the relationship between the clutch A and the steering shaft member 1 is kept in a non-contact or slidable state.

Although the steering shaft is shown as the steering shaft member 1 according to the embodiment of the present invention, the present invention is not limited to this, and a steering shaft member such as a steering pinion and a steering rack also exists.

[0040]

According to the first aspect of the present invention, the steering shaft member 1 and the two disk-shaped cover members 2, 2 mounted on the steering shaft member 1 at appropriate intervals in the axial direction are provided. A clutch A that is engaged with and connected to the steering shaft member 1 by a rotating operation of an outer ring member 6 provided at a radially outer peripheral portion.
A worm wheel 1 provided on the outer periphery of the outer race member 6
5 and a worm 16 meshing with the worm wheel 15
A motor 17 for rotating the worm 16 and a motor 17 for detecting torsion of the steering shaft member 1.
The transmission mechanism of the electric power steering system including the sensor 18 for driving the power steering device has effects that the structure and the device assembling work are simple and the steering can be reliably performed.

Further, since the steering shaft member 1 and the one-way two-way type clutch A are not always connected, it is possible to prevent gear breakage of the speed reducer due to an unexpected rotation torque from the steering shaft member 1 side. .
The return of the steering wheel is the same as that of the manual steering by stopping the rotation of the motor 17, and it is possible to prevent the return of the steering wheel from being deteriorated due to the friction of the motor 17 when the conventional steering wheel returns. it can.

If the motor 17 is not rotated,
Since the clutch A is not connected to the steering shaft member 1, the rotation is transmitted from the steering shaft member 1 to the motor 17 via the speed reducer as in the related art, and the motor that is applied to the steering shaft member 1 when power assist is not performed. 1
7 can be eliminated. Therefore, the general-purpose motor 17 can be used without using the special motor 17 having a small friction torque of the motor 17.

According to a second aspect of the present invention, in the first aspect, the clutch A has a plurality of sprags disposed between the two disk-shaped cover members 2 so as to be tiltable in the axial circumferential direction of the steering shaft member 1. , And an elastic member 5 that keeps the sprags 3, 3,... Always in a neutral state, and the sprags 3, 3,. By providing a transmission mechanism for electric power steering in which the steering shaft member 1 is tilted and pressed and engaged, the simplest structure in which a clutch device is attached to the steering shaft member 1 can be obtained.

Further, since the clutch A does not include the steering shaft member 1 in its structure, the structure is not large and complicated, and the number of parts can be reduced.
Further, since the structure of the clutch can be made separate from the steering shaft member 1, versatility is enhanced. The above effect will be described in detail. A state in which a sprag 3, a holding member 4, an elastic member 5, and an outer ring member 6 are combined with the disc-shaped cover members 2, 2 without performing any processing on the steering shaft member 1. The clutch can be constituted only by mounting the clutch on the steering shaft member 1. Further, the steering shaft member 1 can be independently rotated, and the sprags 3, 3,... Are pressed and engaged with the steering shaft member 1 only by rotating the outer ring member 6 by an external power source, thereby disengaging the clutch. It works and is extremely easy to operate.

Next, according to a third aspect of the present invention, in the first aspect, the clutch A comprises a disk-shaped cover member 2 on one side of the disk-shaped cover members 2 and 2 and a disk-shaped member on the other side. Cover material 2
A is pivotally supported by the pivot portion P _1, P ₂ of different two places in the radial direction, a plurality of sprags 3, 3 tilts in the rotational direction of the displacement of the two disk-like cover member 2, 2, ... are provided The outer ring member 6 is fixed to one of the disc-shaped cover members 2 at a radially outer peripheral portion of the disc-shaped cover members 2 and 2;
The sprag 3 is tilted by the rotation of the outer ring member 6, and the transmission mechanism of the electric power steering is formed by pressing and engaging the inner peripheral surface of the outer ring member 6 with the steering shaft member 1. Can be stabilized.

[0046] More specifically the above effects, sprags 3,3 mounted between disc-shaped cover member 2, 2, ... are pivotally supported by different pivot portion P _1, P ₂ in the radial direction of the two positions, Since the outer ring member 6 is fixed to one of the disc-shaped cover members 2, the sprags 3 tilted by the rotation of the outer ring member 6 can be stably held.

Next, according to a fourth aspect of the present invention, in the first aspect, the clutch A is disposed between the two disk-shaped cover members 2 and 2 and is pivotally connected to the disk-shaped cover member 2 on one side. Branch P
A plurality of sprags 3, 3 is pivotally supported at _3, ... are provided,
An outer ring fixed to one of the disk-shaped cover members 2 at the radially outer peripheral portion of the disk-shaped cover members 2 and 2 and having an inner peripheral engagement surface 6b for engaging with the sprag 3 Member 6
The transmission mechanism of the electric power steering is characterized in that the sprags 3 are tilted by the rotation of and the steering shaft member 1 is pressed and engaged, so that the operation of the clutch A is stabilized and And the outer ring member 6 are securely engaged, and a reliable clutch can be obtained.

Next, according to a fifth aspect of the present invention, in the first aspect, the clutch A rotates together with the steering shaft member 1 and the inner ring member 10 located between the two disk-shaped cover members 2, 2. A roller-shaped engaging body 12 comprising two roller-shaped members 12a, 12a and a resilient member 12b for repelling the two roller-shaped members 12a, 12a mutually is provided, and an inner peripheral engaging surface 6b of the outer ring member 6 is provided. Has a polygonal shape, the roller-shaped engaging bodies 12 are arranged at substantially equal intervals between the inner ring member 10 and the inner peripheral engaging surface 6b, and the inner peripheral engaging surface 6b is rotated by rotation of the outer ring member 6. The roller-shaped engaging body 12 is engaged,
By providing the clutch device by pressing the roller-shaped engagement body 12 toward the inner ring member 10, the steering shaft member 1 is pressed by the roller-shaped engagement body 12 via the inner ring member 10. 1 can be improved in durability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the configuration of the present invention.

FIG. 2 is an enlarged view showing a combination of a clutch and a worm wheel gear mechanism.

FIG. 3 is a longitudinal sectional front view of the first embodiment.

FIG. 4 is a longitudinal sectional side view of the first embodiment.

FIG. 5 is a longitudinal sectional front view showing an operation state of the first embodiment.

FIG. 6A is an enlarged longitudinal sectional front view of a main part showing a sprag structure according to the first embodiment. FIG. 6B is an enlarged longitudinal sectional front view of an essential part showing an operation of the sprag according to the first embodiment.

7A is an enlarged sectional view of a main part showing another type of sprag structure of the first embodiment; FIG. 7B is an enlarged sectional view of a main part showing the action of a sprag in another type of the first embodiment; (C) is an enlarged sectional view of a main part showing a further type of sprag structure of the first embodiment. (D) is an enlarged sectional view of a main part showing the action of a sprag in still another type of the first embodiment.

FIG. 8 is a longitudinal sectional front view of the second embodiment.

FIG. 9A is a vertical sectional side view of the second embodiment, FIG. 9B is an enlarged vertical sectional side view of a main part of the second embodiment, and FIG. 9C is a vertical sectional side view of another type different from (B) of the second embodiment. Enlarged vertical side view

FIG. 10 is an operation state diagram of a sprag according to the second embodiment.

11A is an enlarged cross-sectional view of a main part showing another type of sprag structure of the second embodiment. FIG. 11B is an enlarged cross-sectional view of a main part showing the action of a sprag in another type of the second embodiment. (C) is an enlarged cross-sectional view of a main part showing still another type of sprag structure of the second embodiment. (D) is an enlarged cross-sectional view of a main part showing operation of a sprag in still another type of the second embodiment.

FIG. 12 is a longitudinal sectional front view of the third embodiment.

FIG. 13 is a longitudinal sectional side view of the third embodiment.

FIG. 14 is a longitudinal sectional front view showing an operation state of the third embodiment.

15A is an enlarged view showing an operation state of the wedge-shaped engagement of the third embodiment. FIG. 15B is a view showing an operation state of the wedge-shaped engagement of the third embodiment in a direction opposite to that of FIG. Enlarged view

[Explanation of symbols]

A: clutch 1: steering shaft member 2: disk-shaped cover member 3: sprag 3b: outer ring side engaging surface 5: elastic member 6: outer ring member 6b: inner peripheral engaging surface 10: inner ring member 11: bush 12: roller Jo engager 12a ... roll-like elements 12b ... resilient member 15 ... worm wheel 16 ... worm 17 ... motor 18 ... sensor _{P 1, P 2, P 3} ... pivot portion

Claims (5)

[Claims] 1. Rotation of a steering shaft member and an outer ring member provided at a radially outer peripheral portion between two disk-shaped cover members mounted on the steering shaft member at appropriate intervals in the axial direction. A clutch engaged with and connected to the steering shaft member in operation, a worm wheel provided on an outer periphery of the outer race member, a worm meshing with the worm wheel, a motor for rotating the worm, and the steering shaft member And a sensor for detecting the torsion of the motor and driving the motor. 2. The clutch according to claim 1, wherein the clutch includes a plurality of sprags disposed between the two disc-shaped cover members so as to be tiltable in a circumferential direction of the steering shaft member, and the sprags are always maintained in a neutral state. An elastic member is provided, and the sprags are tilted by the rotation of the outer ring member, and the sprags are pressed and engaged with the steering shaft member. 3. The pivoting part according to claim 1, wherein the clutch has two disc-shaped cover members on one side of the disc-shaped cover members and two disc-shaped cover members on the other side in the radial direction. A plurality of sprags pivotally supported by each other and tilting in a rotational direction of the two disk-shaped cover members, and provided at one of the disk-shaped cover members at a radially outer peripheral portion of the disk-shaped cover member. The transmission of electric power steering, wherein the outer ring member is fixed, and the sprags are tilted by the rotation of the outer ring member to press and engage the inner peripheral surface of the outer ring member with the steering shaft member. mechanism. 4. The clutch according to claim 1, wherein the clutch is provided between the disc-shaped cover members, and is provided with a plurality of sprags pivotally supported by a disc-shaped cover member on one side thereof and a pivot portion. The outer ring member, which is fixed to one of the disk-shaped cover members at an outer peripheral portion in the radial direction of the disk-shaped cover member and has an inner peripheral engagement surface that engages with the sprag, is rotated. A transmission mechanism for electric power steering, wherein the sprags are tilted to press and engage the steering shaft member. 5. The clutch according to claim 1, wherein the clutch rotates together with the steering shaft member and connects an inner ring member located between the disc-shaped cover members, two roller-shaped members, and both roller-shaped members. A roller-shaped engaging body comprising a resilient member for repelling the outer ring member, the inner peripheral engaging surface of the outer ring member is formed in a polygonal shape, and the rollers are provided at substantially equal intervals between the inner ring member and the inner peripheral engaging surface. An electric engaging member is arranged, the roller-shaped engaging member is engaged with the inner peripheral engaging surface with the rotation of the outer ring member, and the roller-shaped engaging member is pressed toward the inner ring member. Power steering transmission mechanism.