JP2661670B2 - Clutch device - Google Patents

Description

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

[Conventional technology]

Generally, in an electric power steering device of an automobile, an input shaft connected to a steering wheel shaft and an output shaft for steering wheels are connected by a torsion bar, and the torsion of the torsion bar is detected by a sensor. When the sensor detects the twist, the motor is driven through the control device, and the rotation of the motor is transmitted to the output shaft.

In addition, in order to solve the problem that a drive system including a torque transmission mechanism that transmits the rotation of the motor to an output shaft occurs and the manual operation force of the steering wheel becomes excessive, and the steering becomes substantially impossible, A clutch is incorporated in a torque transmission system that transmits rotation to an output shaft, and when an abnormality occurs in the drive system, the clutch is disconnected to disconnect the drive system.

Although an electromagnetic clutch can be used as the clutch, there is a disadvantage that the clutch becomes large to obtain a required transmission torque. In addition, the use of the meshing clutch has a problem that a large force is required for canceling the meshing when the meshing load is applied.

In order to solve the above-mentioned problems, the present applicant has already proposed a small clutch device capable of mechanically switching two inputs without transmitting an external operation and transmitting the two inputs to an output shaft for steering wheels. (Japanese Patent Application No. 62-25521)
Specification).

7 and 8 show the clutch device. In this clutch device, a cylindrical cam surface 2 is provided on the inner peripheral surface of an outer ring 1,
One of the three bearings 3, 4 supports the input shaft 5, the other bearing 4 supports the output shaft 6, and the input shaft 5 has a retainer that fits outside the end of the output shaft 6. The output shaft 6 has an inclined cam surface 8 formed on the outer periphery of an end portion that enters the retainer 7.

In the cage 7, a pocket 9 is formed at a position facing the inclined cam surface 8, and a pair of cam members 10, 10 'formed of rollers and the cam members 10, 10' are formed in the pocket 9. A spring 11 is incorporated which presses against the circumferentially opposed end surfaces of the cam surfaces 9 and holds the cam surfaces 2 and 8 at positions not engaged with the inner and outer cam surfaces 2 and 8.

Further, a pin 12 protrudes from the outer periphery of the end of the output shaft 6, and a fitting hole 13 into which the pin 12 fits is formed in the retainer 7, and the output shaft 6 and the retainer 7 are separated by a clearance A in the rotational direction. A torsion bar 14 is provided between the input shaft 5 and the output shaft 6 so as to engage with each other and hold the rotation position clearance A at a neutral position.

When the clutch device having the above configuration is incorporated in an electric power steering device, the input shaft 5 is connected to a handle shaft, and the output shaft 6 is connected to a shaft for steering wheels. And, a sensor for detecting the torsion of the torsion bar 14 is provided,
When the sensor detects that the torsion bar 14 is twisted by a predetermined amount, the motor is rotated through the control device, and the rotation of the motor is transmitted to the outer ring 1.

In the above-described assembling, when the handle operation force exceeds the set torque of the torsion bar 14, the retainer 7 rotates with respect to the output shaft 6, and among the pair of cam members 10, 10 ',
The cam member on the front side in the rotation direction of the retainer 7 has inner and outer cam surfaces 2,
8 to operate the clutch.

On the other hand, the sensor for detecting the torsion of the torsion bar 14 is operated to drive the motor. At this time, since the clutch is already operating, the rotation of the motor is transmitted to the output shaft 6 via the outer ring 1 and the cam member. Is done.

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

If the drive system of the outer wheel 1 including the motor does not operate due to an abnormality at this time, when the handle is operated, the retainer 7 rotates with respect to the output shaft 6 and the pair of cam members 10 and Of the 10 ', the cam member on the front side in the rotation direction of the retainer 7 is pushed in the circumferential direction and attempts to engage with the inner and outer cam surfaces 2 and 8, but the clutch does not operate depending on the rotation from the retainer 7. The cam member slides on the cam surface 2 of the outer race 1.

Therefore, rotation is transmitted from the retainer 7 to the output shaft 6 via the pin 12 and is isolated from the drive system,
The handle operation force by manual operation is not excessive.

[Problems to be solved by the invention]

By the way, when the clutch device is used as an electric power steering device, 5 to 10
It is necessary to provide a torsion of about を and establish the clutch within the set angle.If the torsion angle of the torsion bar 14 is small, the output control of the outer ring drive motor within the small angle can be controlled from the minimum to the maximum. Need to do,
Extremely high resolution sensors are required.

In the clutch device, since the input shaft 5 and the retainer 7 have an integral structure, the retainer 7 is rotated with respect to the output shaft 6, and the cam members 10, 10 'are engaged with the inner and outer cam surfaces 2, 8. In this case, it is necessary to absorb the rotation of the retainer 7 for giving the torsion set to the torsion bar 14 from the engaged state by the contraction of the spring 11.

However, in the clutch device, the pair of cam members 10,
The rotation of the retainer 7 is absorbed by the spring 11 due to the structural problem of incorporating the spring 11 between 10 'and the dimensional problem of determining the circumferential length of the pocket 9 corresponding to the inclined cam surface 8 of the output shaft 6. May be difficult to perform.

Accordingly, it is a technical object of the present invention to further improve the above-described clutch device so that an extremely large torsion angle can be given to the torsion bar.

[Means for solving the problem]

In order to solve the above problems, in the present invention,
The retainer is provided rotatably with respect to the input shaft, and the rotation of the input shaft is transmitted to the retainer by a spring incorporated between the input shaft and the retainer.

[Action]

According to the above configuration, the engagement between the cam member and the cam surface incorporated in the pocket of the retainer and the contraction of the spring that presses the cam member in the circumferential direction in a direction not engaging the cam member with the cam surface are achieved. When the retainer is stopped from rotating and the input shaft is further rotated, the spring incorporated between the retainer and the retainer is contracted, and only the input shaft can be further rotated. Therefore, a large torsion can be given to the torsion bar connecting the input shaft and the output shaft.

Embodiment An embodiment of the present invention will be described below with reference to FIGS.

1 to 3 show a first embodiment of a clutch device according to the present invention. In this embodiment, the same components as those in FIGS. 7 and 8 described above are denoted by the same reference numerals, and description thereof will be omitted.

In the first embodiment, a square hole 15 is provided on the end face of the input shaft 5 instead of the pin 12 and the fitting hole 13 shown in FIG. And the input shaft 5 and the output shaft 6 are engaged with a clearance A in the rotation direction. This rotational direction clearance A disappears when the torsion bar 14 connecting the input shaft 5 and the output shaft 6 is twisted by a set amount, and the square hole 15 and the square shaft 16 are engaged.

The retainer 7 'is rotatably supported on the input shaft 5, and a coil spring 17 is incorporated between the retainer 7' and a fitting portion of the input shaft 5. One end of the coil spring 17 is connected to the input shaft 5, and the other end is connected to the holder 7 '. The retainer 7 ′ is guided on the cam surface 2 of the outer race 1.

As described above, the input shaft 5 is
The rotation of the input shaft 5 can be transmitted to the holder 7 ′ via the coil spring 17 by connecting the shaft 7 and the holder 7 ′, and the rotation of the input shaft 5 with respect to the holder 7 ′ is deformed by the coil spring 17. Can be absorbed by

Therefore, when the input shaft 5 is rotated with respect to the output shaft 6,
The retainer 7 ′ rotates together with the input shaft 5, and of the pair of cam members 10, 10 ′ incorporated in the pocket 9, the cam member on the front side in the retainer rotation direction is used as the cam surface of the outer ring 1 and the output shaft 6. 2, 8 can be cam-engaged. Further, when the input shaft 5 is further rotated from the engaged state, the spring 11 incorporated between the cam members 10 and 10 'contracts, and even if the retainer 7' is prevented from rotating due to the contraction of the spring 11, the input shaft 5 does not rotate. Can be further rotated.

For this reason, large torsion can be given to the torsion bar 14. In addition, a cam member incorporated in the pocket 9
The movement margin of 10, 10 'may be small, and the cam member 1
A spring 11 having a small contraction amount can be used as the spring 11 incorporated between 0 and 10 '.

4 to 6 show a second embodiment of the clutch device according to the present invention. In this embodiment, the output shaft 6
The cam surface 8 provided on the outer periphery of the cam is a cylindrical cam surface.
Further, a cam member 10 ″ made of sprags is used instead of the cam members 10 and 10 ′ made of rollers.
The radius of the arcuate surfaces 18 and 19 formed on the outer and inner diameter sides is larger than 1/2 of the dimension between the outer ring 1 and the cam surfaces 2 and 8 of the output shaft 6, and the center of both arcuate surfaces 18 and 19 Is slightly smaller than the dimension between the cam surfaces 2 and 8.

Therefore, when the cam member 10 ″ falls down in the circumferential direction of the cam surfaces 2 and 8, the arcuate surfaces 18 and 19 of the cam member 10 ″ engage with the opposed cam surfaces 2 and 8.

Two retainers 20 and 21 having different diameters are incorporated between the outer ring 1 and the output shaft 6, and the large-diameter retainer 20 has a pocket into which the outer end of the cam member 10 ″ fits. 22 are provided.

On the other hand, pockets 23 are formed in the small-diameter retainer 21 so that the inner-diameter-side ends of the cam members 10 ″ are fitted. In each pocket 22, the cam members 10 ″ are provided with the cam surfaces 2, 8. A spring 24 for holding the cam in a state where the cam is not engaged is incorporated.

Of the two cages 20, 21, the smaller-diameter cage 21 is fixed to the output shaft 6, and the larger-diameter cage 20 is rotatably fitted to the end of the input shaft 5. A plurality of protrusions 25 are formed at equal intervals on the inner diameter surface of the large diameter side retainer 20, while
A projection 26 fitted between the projections 25 is provided on the outer peripheral surface of the input shaft 5.
A spring 27 is provided between the projecting portions 25 and 26 which are provided and face each other in the circumferential direction.

Since other configurations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

As described above, by incorporating the spring 27 between the retainer 20 on the large diameter side and the input shaft 5, the cam member 10 ″ is engaged with the cam surfaces 2 and 8 as in the first embodiment. Cage 20
Even when the rotation of the torsion bar 14 is stopped, the input shaft 5 can be rotated with respect to the retainer 20.
Can be given a large twist.

〔The invention's effect〕

As described above, in the present invention, since the rotation of the input shaft is transmitted to the retainer via the spring, it is possible to give a large torsion to the torsion bar,
As the sensor for detecting the torsion bar torsion, a low-cost and low-cost sensor can be used.

[Brief description of the drawings]

1 is a longitudinal sectional front view showing a first embodiment of a clutch device according to the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. FIG. 4 is a vertical sectional front view showing a second embodiment of the clutch device, FIG. 5 is a cross-sectional view taken along line VV of FIG. 4,
6 is a sectional view taken along the line VI-VI of FIG. 4, FIG. 7 is a longitudinal sectional front view showing a conventional clutch device, and FIG.
It is sectional drawing along the VIII-VIII line. 1 ... outer ring, 2 ... cam surface, 5 ... input shaft, 6 ... output shaft, 7, 7 ', 20, 21 ... retainer, 8 ... cam surface, 9, 22 ... pocket, 10 , 10 ', 10 "... cam member, 11, 24 ... spring, 14 ... torsion bar, 15 ... square hole, 16 ... square shaft, 17, 27 ... spring.

Claims (1)

(57) [Claims] A cam surface is provided on an inner surface of an outer ring, a retainer fitted inside the outer ring is provided at an end of an input shaft provided coaxially with the outer ring, and an output shaft provided coaxially with the input shaft. A cam surface is provided on an outer periphery of an end fitted inside the retainer, a pocket is formed in the retainer, and a cam member is provided in the pocket.
A spring for holding the cam member at a position where the cam member does not engage with the inner and outer cam surfaces is incorporated, the input shaft and the output shaft are engaged with a clearance in the rotation direction, and the torsion is held at a neutral position in the clearance in the rotation direction. In a clutch device in which a bar is provided between an input shaft and an output shaft, the retainer is rotatably provided with respect to the input shaft, and between the retainer and the input shaft, the rotation of the input shaft is applied to the retainer. A clutch device incorporating a transmission spring.