JP2713573B2 - clutch - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a clutch, and more particularly to a clutch suitable for an electric power steering device.

[Conventional technology]

FIG. 12 shows a general configuration of the electric power steering device. In this device, when the steering wheel 1 is rotated right or left, a torque is generated on the handle shaft 3 by resistance from the wheels 2. This torque is detected by a sensor 4 provided on the handle shaft 3, and a motor 6 is driven through a control device 5. The drive shaft of the motor 6 is connected to a pinion 8 of the handle shaft 3 via a speed reducer 7, and a rack 9
, The wheels 2 are steered. Thus, the wheels can be steered with a very small steering wheel operating force.

[Problems to be solved by the invention]

However, in such an electric power steering apparatus, when an abnormality occurs in a drive system including the control device 5, the motor 6, and the speed reducer 7, and when these do not operate, the speed reducer 7 and the motor 6 Is connected, the manual operation force of the steering wheel becomes excessively large, and there is a problem that the steering becomes substantially impossible.

Therefore, a method of interposing a clutch device 10 between the speed reducer 7 and the pinion 8 is known.

Although an electromagnetic clutch can be used as the clutch device 10 in this case, there is a disadvantage that the clutch device 10 becomes large in size to obtain a desired transmission torque. In addition, when the meshing clutch is used, there is a problem that a large force is required for positioning the meshing and releasing the meshing under load.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and an object of the invention is to provide a small-sized clutch which is extremely suitable for being incorporated into an electric power steering device, has high transmission reliability, and has a large torque transmission capacity. Is to do.

[Means for solving the problem]

In order to solve the above-mentioned problems, in the clutch of the present invention, a cylindrical retainer is incorporated between a clutch outer ring and a clutch inner ring incorporated therein, and an inner diameter surface of the clutch outer ring and an outer diameter surface of the clutch inner ring are incorporated. A plurality of cam surfaces are provided on one side, a cylindrical surface is formed on the other side, and a wedge-shaped space gradually narrowing toward both ends in the circumferential direction is formed between the cam surface and the cylindrical surface, and the cage has the wedge-shaped space and the wedge-shaped space. A pocket is formed at a corresponding position, and a rolling element and a pair of springs for holding the rolling element at the center in the circumferential direction of the pocket are incorporated in the pocket, and the retainer and the member on the side having the cam surface are assembled. A torque transmission mechanism having a rotational direction clearance is provided between them, and the torque transmitting mechanism is held at the neutral position of the rotational direction clearance, and when a rotational force exceeding a set torque is applied, the rotational direction clearance does not exist. A torque setting elastic member that elastically deforms is provided between the retainer and the member having the cam surface, and at the neutral position, the rolling elements housed in the pockets have a pair of rolling members in the forward and reverse rotation directions of the wedge-shaped space. The configuration does not engage with any of the narrow portions.

[Action]

When the clutch configured as described above is used for a power steering device, for example, the retainer is connected to the handle shaft, and the member having the cam surface of the clutch outer wheel and the clutch inner wheel is connected to the pinion shaft. Then, the member having the cylindrical surface is connected to the motor.

Accordingly, when the rotation torque applied to the handle shaft is equal to or less than the set torque of the torque setting elastic member, the flexure of the torque setting elastic member is small and the rotation direction clearance is substantially at the neutral position. The rolling element housed in the inside is located in the wide portion of the wedge-shaped space formed by the cam surface and the cylindrical surface, the clutch does not operate, and the rotation of the handle shaft is transmitted to the pinion shaft via the torque setting elastic member. be able to.

When the rotational torque applied to the handle shaft exceeds the torque set by the torque setting elastic member, the handle shaft greatly deflects the torque setting elastic member, and the retainer is relatively moved with respect to the clutch outer ring and the clutch inner ring until there is no clearance in the rotation direction. The rolling element bites into a narrow portion of the wedge-shaped space formed by the cylindrical surface and the cam surface, and the clutch operates. At this time, of the clutch outer ring and the clutch inner ring, the member having the cylindrical surface is rotationally driven by the motor. The rotation is
Since the power is transmitted to the member having the cam surface via the clutch, the pinion shaft rotates, and the steering of the wheels can be performed with a very small steering wheel operating force.

Should the drive system, including the motor, become abnormal and become inoperative, the rotation imparted to the cage from the handle shaft will engage the torque transmission mechanism and cause the clutch outer ring and clutch inner ring to face each other. The rolling element trying to bite into the wedge-shaped space slides on the cylindrical surface, and the steering wheel operating force is transmitted to the pinion shaft in a state where the rolling element is cut off from the driving system, so that the steering wheel manual operation force is not excessively increased.

Also, when the steering wheel is returned from the wheel side when recovering from a curve, the driver applies only torque enough to slide the steering wheel lightly by hand, so that the torque is less than the set torque, the clutch does not operate with the driving system, It is in the state of manual operation.

Therefore, by appropriately setting the spring force of the torque setting elastic member, manual operation is performed when the torque is equal to or less than the set torque, and automatically switched to power steering when the torque exceeds the set torque, and an abnormality occurs in the drive system including the motor and the like. Even at this time, the steering wheel operation force by manual operation is not excessive, and the steering wheel is smoothly returned without giving the driver an uncomfortable feeling when recovering from the curve.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 11.

1 to 7 show a first embodiment of a clutch device according to the present invention.

As shown in FIG. 1, the clutch outer ring 11 has a cylindrical shape, and a clutch inner ring 12 is incorporated inside the outer ring. An output shaft 13 provided on the inner race 12 and the clutch outer race 11 are supported via a bearing 14 so as to be relatively rotatable.

A cylindrical retainer 15 is incorporated between the clutch outer ring 11 and the clutch inner ring 12, and an input shaft 16 and a clutch outer ring 11 provided at a closed end of the retainer 15 are relatively rotated via a bearing 17. It is movably supported.

Further, the clutch inner ring 12 is provided with a small-diameter shaft portion 18 on an end surface facing the closed end of the retainer 15, and the small-diameter shaft portion 18 is inserted into a concave portion 19 provided at the closed end of the retainer 15, and a bearing 20 is provided. And is rotatably supported via the.

On the inner diameter surface of the clutch outer ring 11, as shown in FIG.
A cylindrical surface 21 is formed. On the other hand, the outer diameter surface of the clutch inner ring 12 is formed in a polygonal shape, and each plane thereof is a cam surface 22,
Between the cam surface 22 and the cylindrical surface 21, there is formed a wedge-shaped space 23 that gradually narrows toward both ends in the circumferential direction.

The retainer 15 has a pocket 24 corresponding to the wedge-shaped space 23.
As shown in FIG. 3, a concave portion 26 is formed at a central portion in the axial direction of a pair of rolling element guide surfaces 25 which oppose each other in the circumferential direction of the pocket 24.

The rolling element 27 housed inside the pocket 24 is pushed from both sides by a pair of springs 28, 28 incorporated in the concave portion 26 and held at the circumferential center of the pocket 24, and the rolling element 27 and the rolling element at that position As shown in FIG. 4, a clearance X in the rotation direction is provided between the guide surface 25 and the guide surface 25.

The rolling element 27 is moved by a spring
When pushed by 28 and bites into the narrow part of the wedge-shaped space 23, when the cage 15 is rotated in the opposite direction in the biting state,
The rolling element guide surface 25 pushes the rolling element 27 to release the biting.

As shown in FIGS. 1 and 6, a torque transmission mechanism T for transmitting the rotation of the cage 15 to the clutch inner ring 12 is provided between the cage 15 and the clutch inner ring 12. The torque transmission mechanism T is provided with a pin 29
The pin 29 is inserted into a fitting hole 30 provided at the closed end of the retainer 15, and a clearance A in the rotational direction is provided between the pin 29 and the fitting hole 30. Clearance A in this rotation direction
Is larger than the rotational direction clearance X provided between the rolling element guide surface 25 and the rolling element 27.

The input shaft 16 and the output shaft 13 are provided with an insertion hole 31 in the axial direction, and both ends of the torsion bar 32 as a torque setting elastic member inserted into the insertion hole 31 are fixed to each shaft. . The pin 29 is held at the neutral position of the fitting hole 30 by the spring force of the torsion bar 32. In the neutral position, the rolling elements 27 are not engaged with any of the narrow portions facing each other in the circumferential direction of the wedge-shaped space 23.

Here, the spring force of the torsion bar 32 is such that when a rotational force of a certain torque or more acts on the input shaft 16, the torsion bar 32 is twisted until the clearance A in the rotational direction disappears,
And the clutch inner ring 12 is engaged via the pin 29.

The clutch shown in the first embodiment has the above structure,
When this clutch device is used in an electric power steering device, as shown in FIG.
A handle shaft 41 with 40 is connected, and a rack 42
Is connected to the shaft 44 of the pinion 43 that meshes with.

Further, a sensor 45 for detecting the twist of the handle shaft 41 is provided, and the rotation of the motor 47 driven through the control device 46 by the detection sensor 45 is transmitted to the clutch outer ring 11 via the gear transmission mechanism 48. For this reason, the clutch outer ring 11
In this case, as shown in FIG. 1, a gear 33 is provided on the outer periphery.

In the above assembled state, when the handle 40 is operated to rotate and the retainer 15 of the input shaft 16 is given a rotational force to the left in FIG. 4, the handle operation force is equal to or less than the set torque of the torsion bar 32. , The torsion bar 32
Is small and the retainer 15 does not relatively rotate relatively to the clutch inner ring 12, so that the rolling element 27 does not bite into the narrow portion of the wedge-shaped space 23, and the clutch does not operate.

Therefore, when the steering wheel operating force is small, there is no transmission of rotational force from the clutch outer wheel 11 to the clutch inner wheel 12,
Manual steering operation.

When the handle operation force increases and exceeds the set torque of the torsion bar 32, the torsion bar 32 is twisted,
The retainer 15 rotates leftward relative to the clutch inner ring 12, and causes the rolling element 27 to bite into the narrow portion on the left side of the wedge-shaped space 23 via the spring 28 (see FIG. 5). At this time, a small clearance a in the rotational direction is formed between the pin 29 and the fitting hole 30, as shown in FIG.
Is a rolling element 27 shown in FIG. 5 and a rolling element guide surface 25 on the right side thereof.
It is smaller than the clearance X 'in the rotational direction between the two.

On the other hand, an operating force is transmitted to the wheels, and a torque is generated on the handle shaft 41 by resistance from the wheels. The torque is detected by a sensor 45 provided on the handle shaft 41, and the motor 47 is driven through the control device 46. The rotation of the motor 47 is transmitted to the clutch outer ring 11. At this time, since the clutch is already operating, the rotation of the motor 47
Is transmitted to the clutch inner ring 12 via the rolling elements 27 and transmitted to the wheels via the output shaft 13, the pinion shaft 44, the pinion 43 and the rack 42.

As described above, when the steering wheel operating force exceeds the set torque, the mode is switched to the power steering, and the wheels can be steered by a very small steering wheel operating force.

If an abnormality occurs in the drive system including the control device 46 and the motor 47 and they do not operate, when the handle 40 is operated, the retainer 15 connected to the handle shaft 41 is rotated. The retainer 15 is relatively rotated to the left with respect to the clutch inner ring 12, and the rolling element 27 is pressed by the narrow portion of the wedge-shaped space 23 (see FIG. 5).
0, the rotational force from the retainer 15 is transmitted to the clutch inner ring 12, the clutch does not operate, and the rolling element slides on the cylindrical surface 21 of the clutch outer ring 11.

Therefore, from the retainer 15 to the pin 29, the clutch inner ring 12,
The manual operation force is transmitted to the wheels via the pinion shaft 44, the pinion 43, and the rack 42, and is disconnected from the drive system, so that the manual operation force of the handle does not become excessive.

Further, an operation when the steering wheel is returned from the wheel side when the drive system does not operate will be described. When the vehicle recovers from a curve, force is transmitted from the wheels to the rack 42, the pinion 43, the pinion shaft 44, and the clutch inner wheel 12. The driver applies only a torque enough to slide the steering wheel by hand with respect to the steering wheel returning force, and therefore the torque is not more than the set torque of the torsion bar 32. In this case, since the retainer 15 does not relatively rotate relative to the clutch inner ring 12, the rolling elements 27 accommodated in the pockets 24 of the retainer 15 are not pressed by the narrow portion of the wedge-shaped space 23. Therefore, the clutch is not operated, and the retainer 15 and the handle 40 connected thereto are returned in a state where the clutch inner ring 12 is disconnected from the clutch outer ring 11 (unrotatable).

Therefore, when the vehicle recovers from the curve, the steering wheel is smoothly returned without giving the driver an uncomfortable feeling.

FIG. 9 shows a second embodiment of the present invention. In this clutch, the cam surface 22 formed on the outer diameter surface of the clutch inner ring 12 is a concave V-shaped curved surface.

FIG. 10 shows a third embodiment of the present invention, wherein the cam surface 22 provided on the outer diameter surface of the clutch inner ring 12 is a concave arc-shaped surface.

As in the second and third embodiments, the cam surface 22 is
When the curved surface or the arc surface is used, the rotation angle of the retainer 15 for making the rolling element 27 bite into the narrow portion of the wedge-shaped space 23 is reduced as compared with the cam surface 22 formed of the flat surface of the first embodiment. Can be.

FIG. 11 shows a fourth embodiment of the clutch of the present invention. In this clutch, a concave cam surface 22 ′ is provided on the inner diameter surface of the clutch outer ring 11, and a cylindrical surface is formed on the outer diameter surface of the clutch inner ring 12.
21 'is formed, and the cam surface and the cylindrical surface are arranged in reverse to the first embodiment. In this case, the clutch outer ring 11 and the retainer 15
A pin is provided on one of the opposing surfaces of the pair, and the pin is inserted into a fitting hole formed on the other side with a rotational clearance. When this clutch is incorporated in the electric power steering device shown in FIG. 8, the clutch outer ring 11 is connected to the pinion shaft 44,
The rotational force of the motor 47 is transmitted to the clutch inner ring 12. In the case of the first embodiment, the retainer 15 and the clutch inner ring
12 and torsion bar 32
32 may be omitted, and instead, a pair of springs may be incorporated on both sides of the pin 29 shown in FIG. 6, and the spring may hold the pin 29 at a neutral position in the clearance in the rotational direction.

〔The invention's effect〕

Since the present invention is configured as described above, the following effects can be obtained.

(B) When the torque is equal to or less than the set torque, the rotational force is transmitted from the cage to the member having the cam surface of the clutch inner ring and the clutch outer ring, and when the torque exceeds the set torque, the member having the cage and the cylindrical surface Is mechanically switched without external control to allow transmission to a member having a cam surface.

Therefore, when the clutch of the present invention is used in an electric power steering apparatus, the operation is simple when the steering wheel operating force is equal to or less than the set torque with a simple configuration using the set spring force of the torque setting elastic member. When the power exceeds the limit, it is possible to automatically switch to power steering, which is very suitable for incorporation into a power steering device.

(B) Since the retainer is connected to the member having the cam surface by a mechanical engagement structure, the transmission reliability is high.

(C) Since one rolling element is accommodated in the pocket of the cage, the circumferential length of the cam surface formed on one of the clutch outer ring and the clutch inner ring can be shortened.
Therefore, the number of rolling elements incorporated can be increased, and the capacity of transmission torque can be increased.

(D) Since the number of components is small, including the outer ring of the clutch, the inner ring of the clutch, the retainer, and the rolling elements, assembly is easy and a small clutch can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a clutch according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. FIG. 4, FIG. 4 is a partially enlarged sectional view of the same, FIG. 5 is a sectional view showing an operating state of the same, FIG. 6 is a longitudinal sectional side view showing an engaging portion of the retainer and the clutch inner ring, and FIG. FIG. 8 is a longitudinal sectional side view showing an operating state of the same, FIG. 8 is a schematic view showing a state in which the clutch of the present invention is incorporated in an electric power steering device, and FIGS. 9 to 11 are other embodiments of the clutch of the present invention. FIG. 12 is an enlarged sectional view showing an example, and FIG. 12 is a schematic view showing a conventional electric power steering apparatus. 11 ... clutch outer ring, 12 ... clutch inner ring, 15 ... cage, 21 ... cylindrical surface, 22 ... cam surface, 23 ... wedge-shaped space, 24 ... pocket, 27 ... rolling element, 28 ... Spring, 29 Pin, 30 Fitting hole, 32 Torsion bar.

Claims (1)

(57) [Claims] A cylindrical retainer is incorporated between a clutch outer ring and a clutch inner ring incorporated therein, and a plurality of cam surfaces are provided on one of an inner diameter surface of the clutch outer ring and an outer diameter surface of the clutch inner ring. A wedge-shaped space is formed between the cam surface and the cylindrical surface so as to gradually narrow toward both ends in the circumferential direction. A pocket is formed in the retainer at a position corresponding to the wedge-shaped space. A torque transmitting mechanism having a rolling element and a pair of springs for holding the rolling element at the center in the circumferential direction of the pocket, and having a rotational clearance between the retainer and the member having the cam surface. And a torque setting elastic member that holds the torque transmission mechanism at a neutral position of the rotational direction clearance and elastically deforms until the rotational direction clearance disappears when a rotational force exceeding a set torque is applied. Provided between the retainer and the member having the cam surface, at the neutral position, the rolling element accommodated in the pocket does not engage with any of the pair of narrow portions of the wedge-shaped space in the forward and reverse rotation directions. A clutch characterized in that: