Rotation transmission device

Abstract

To provide a rotation transmission device for, when torque having a specified value or higher is input to an input member, enabling the transmission of the torque to both a first output member and a second output member.SOLUTION: A rotation transmission device includes an input member 2, a first output member 3 to which torque is transmitted via a torsion bar 14, a second output member 4, and a clutch part 5 provided between both output members 3, 4. The clutch part 5 has an inside cage 19, an outside cage 20, and an engagement element 21. The inside cage 19 and the outside cage 20 are rotatable integrally with the input member 2 and the first output member 3, respectively. When the torque is lower than a specified value, the engagement element 21 is brought into a disengaging state and the torque is transmitted only to the first output member 3, whereas when the torque is the specified value or higher, the engaging element 21 is brought into an engaging state and the torque is transmitted to both output members 3, 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a rotation transmission device that transmits torque input to an input member to an output member. [Background technology]

[0002] Some rotation transmission devices used in steering devices for automobiles are configured to transmit torque input to an input member to two output members. For example, in the following Patent Document 1, an input shaft 1 and an output shaft 2 are connected via a torsion bar 5, and a clutch unit 3 is provided on the outer diameter side of the output shaft 2. In a torque non-loaded state where the torque between the input and output shafts 1 and 2 is equal to or less than a specified value, torque is output to both the output shaft 2 and an outer ring 31 constituting the clutch unit 3. On the other hand, in a torque loaded state where the torque between the input and output shafts 1 and 2 exceeds a specified value, torque is transmitted only to the output shaft 2, and torque transmission to the outer ring 31 is interrupted.

[0003] In addition, in the following Patent Document 2, a configuration is adopted in which the input shaft 12 and the output shaft 16 are connected via an elastic body 18, and a worm wheel 50 is provided on the outer diameter side of the output shaft 16 via a clutch mechanism 38. In this configuration, contrary to Patent Document 1, when the displacement amount of the elastic body 18 due to the relative rotation between the input shaft 12 and the output shaft 16 is equal to or less than a set value, the clutch mechanism 38 is in a disengaged state, and the input shaft 12 and the worm wheel 50 are separated from each other. On the other hand, when the displacement amount of the elastic body 18 due to the relative rotation between the input shaft 12 and the output shaft 16 exceeds the set value, the clutch mechanism 38 is in an engaged state, and the input shaft 12 and the worm wheel 50 are connected to each other, and an assist force is applied from the worm wheel 50 to the output shaft 16. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-206959 A [Patent Document 2] Patent No. 3269911 Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the application of the rotation transmission device, when a torque equal to or greater than a specified value is input to the input member, a mechanism may be required to transmit the torque separately to the first output member and the second output member. However, in the configuration of Patent Document 1, when the torque input to the input member (input shaft 1) is equal to or greater than a specified value, the torque is transmitted only to the first output member (output shaft 2), and torque transmission to the second output member (outer ring 31) is cut off, so that the input torque cannot be output from two systems.

[0006] Furthermore, in the configuration of Patent Document 2, when the torque (displacement amount of the elastic body 18) exceeds a specified value, the input member (input shaft 12), the first output member (output shaft), and the second output member (worm wheel 50) are connected, and an assist force can be applied to the second output member. However, when an attempt is made to output torque from the second output member (a force in the opposite direction to the assist force acts), the rolling body 74 tilts, causing the clutch mechanism 38 to go into a disengaged state, and therefore torque cannot be output from the second output member.

[0007] The problem that the present invention aims to solve is to provide a rotation transmission device that is capable of transmitting torque to both a first output member and a second output member when a torque equal to or greater than a specified value is input to an input member. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides an input member to which torque is input; a first output member to which torque is transmitted from the input member via a torsion bar, the first output member being allowed to rotate relatively to the input member on the same rotation axis as the input member; a second output member rotatable by torque from the input member; a clutch portion provided between the first output member and the second output member; having the clutch portion includes an inner retainer, an outer retainer provided radially outward of the inner retainer, and an engagement element held by the inner retainer and the outer retainer, the inner retainer is rotatable integrally with the input member, and the outer retainer is rotatable integrally with the first output member, When the torque input to the input member is smaller than a specified value, the engaging element held by both retainers is disengaged between the first output member and the second output member, and the torque input to the input member is transmitted only to the first output member, When the torque input to the input member is equal to or greater than a specified value, the inner retainer rotates ahead of the outer retainer, generating a rotational phase difference, and the engaging elements held by both retainers enter an engaged state between the first output member and the second output member, thereby forming a rotational transmission device in which the torque input to the input member is transmitted to both the first output member and the second output member.

[0009] In this way, by making the inner retainer rotatable integrally with the input member and the outer retainer rotatable integrally with the first output member, when a torque equal to or greater than a specified value is input to the input member and the engaging element of the clutch section is engaged, the torque input to the input member can be transmitted to both the first output member and the second output member while maintaining this engaged state.

[0010] In the above-mentioned configuration, it is preferable that the engaging elements are sprags, so that the clutch portion can be switched between the engaged state and the disengaged state with a simple configuration.

[0011] In all of the above configurations, it is preferable to have a switch pin interposed between the input member and the inner cage, and when the engaging elements are in an engaged state, the switch pin abuts against the first output member from the circumferential direction, thereby transmitting torque from the input member to the first output member. In this way, the torque input to the input member can be reliably transmitted to the first output member via the switch pin.

[0012] In a configuration in which a switch pin is interposed between the input member and the inner cage, it is preferable that a convex portion extending in the radial direction and extending toward the other side of the inner cage or the outer cage is formed on at least one side of the inner cage or the outer cage, thereby ensuring a coaxial state between the inner cage and the outer cage. Effect of the Invention

[0013] By configuring the rotation transmission device of the present invention as described above, when a torque equal to or greater than a specified value is input to the input member and the engaging element of the clutch section is brought into an engaged state, the torque input to the input member can be transmitted to both the first output member and the second output member while maintaining this engaged state. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view showing an embodiment of a rotation transmission device according to the present invention. [Diagram 2] Cross-sectional view of the main part of Figure 1 [Diagram 3] Cross-sectional view taken along line III-III in FIG. [Figure 4] Cross-sectional view of the clutch unit in a non-standby state [Diagram 5] Cross-sectional view of the clutch unit in standby state [Figure 6] Cross-sectional view of the main part when the input shaft is further rotated from the state shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A rotation transmission device 1 according to the present invention will be described with reference to the drawings. As shown in Fig. 1 to Fig. 3, the rotation transmission device 1 mainly comprises an input member 2 (hereinafter referred to as an input shaft and given the same reference number as the input member 2), a first output member 3 (hereinafter referred to as an output shaft and given the same reference number as the first output member 3), a second output member 4 (hereinafter referred to as an outer ring and given the same reference number as the second output member 4), and a clutch unit 5, and is used, for example, in steering devices and drive mechanisms of automobiles. Hereinafter, the direction along the rotation axis of the rotation transmission device 1 is referred to as the axial direction, the direction perpendicular to the rotation axis is referred to as the radial direction, and the direction along the circumference going around the rotation axis is referred to as the circumferential direction.

[0016] The input shaft 2 is a cylindrical member having a through hole 6 formed in its axial center and into which torque is input. The end of the input shaft 2 facing the output shaft 3 is a small diameter portion 7 which has an outer diameter smaller than that of the other portions. The input shaft 2 is formed with a fixing hole 8 passing through its axial center. Furthermore, the small diameter portion 7 of the input shaft 2 is formed with a pin hole 9 extending radially.

[0017] The output shaft 3 is a cylindrical member arranged coaxially with the input shaft 2 and having a through hole 10 formed at its axis. The end of the output shaft 3 facing the input shaft 2 is a large diameter portion 11 in which the inner diameter of the through hole 10 is made larger than that of other portions, and the small diameter portion 7 of the input shaft 2 is arranged inside this large diameter portion 11. The output shaft 3 is formed with a fixing hole 12 passing through its axis. Furthermore, the large diameter portion 11 of the output shaft 3 is formed with an insertion hole 13 passing through the inner and outer circumferential surfaces of this large diameter portion 11.

[0018] A common torsion bar 14 is provided in through holes 6, 10 formed in the input shaft 2 and the output shaft 3, respectively. Both ends of the torsion bar 14 are fixed to the shafts 2, 3 by fixing pins 15, 16 inserted into fixing holes 8, 12 formed in the input shaft 2 and the output shaft 3, respectively. The torsion bar 14 has a shape and is made of a material that allows it to twist when torque is applied, and the action of this torsion bar 14 allows relative rotation between the input shaft 2 and the output shaft 3 on the same rotation axis.

[0019] The outer ring 4 is a cylindrical member provided on the outer diameter side of the small diameter portion 7 of the input shaft 2 and the large diameter portion 11 of the output shaft 3. Bearings 17, 18 are provided at both axial ends of the inner peripheral side of the outer ring 4 and are interposed between the outer ring 4 and the outer peripheral surface of the output shaft 3.

[0020] As shown enlarged in Figure 2, the clutch portion 5 has an inner retainer 19, an outer retainer 20 provided radially outside the inner retainer 19, and an engaging element 21 held by the inner retainer 19 and the outer retainer 20, and is disposed between the outer peripheral surface of the output shaft 3 (large diameter portion 11) and the inner peripheral surface of the outer ring 4.

[0021] As shown in FIG. 3, the inner retainer 19 is a cylindrical member in which a plurality of pockets 22 (eight in this embodiment) are formed at a predetermined angular interval in the circumferential direction. A pin hole 23 extending in the radial direction is formed in one circumferential position of the inner retainer 19. A common switch pin 24 is inserted through an insertion hole 13 formed in the output shaft 3 into the pin holes 9, 23 formed in the input shaft 2 and the inner retainer 19, respectively. The input shaft 2 and the inner retainer 19 rotate together due to the action of this switch pin 24. An elastic member 26 is provided on the circumferential inner surface of the pocket 22 formed in the inner retainer 19, which biases the engaging element 21 held in the pocket 22 in the circumferential direction. In this embodiment, a leaf spring is used as the elastic member 26, but other types of elastic members 26 such as a coil spring can also be used. As shown in FIG. 2, a protrusion 25 is formed on both axial ends of the outer circumferential surface of the inner retainer 19, the protrusion 25 being expanded radially outward.

[0022] As shown in Fig. 3, the outer retainer 20 is a cylindrical member in which pockets 27 are formed in the circumferential direction at the same angular intervals and in the same number as the inner retainer 19. As shown in Fig. 2, a flange portion 28 extending radially inward is formed on one axial end of the outer retainer 20. The inner peripheral surface of the flange portion 28 is fitted into the outer peripheral surface of the output shaft 3, so that the outer retainer 20 and the output shaft 3 rotate together. Furthermore, a protrusion 25 formed on the outer peripheral surface of the inner retainer 19 abuts against the inner peripheral surface of the cylindrical portion of the outer retainer 20, and this abutment allows the inner retainer 19 and the outer retainer 20 to rotate relative to each other while maintaining their coaxiality.

[0023] In this embodiment, the protrusions 25 are formed on the outer peripheral surface of the inner cage 19, but the same effect can be obtained by forming the protrusions 25 on the inner peripheral surface of the outer cage 20. Also, the protrusions 25 can be formed on both the outer peripheral surface of the inner cage 19 and the inner peripheral surface of the outer cage 20. Note that the shape, position, number, etc. of the protrusions 25 shown in Fig. 2 are merely examples and can be changed as appropriate.

[0024] The engaging elements 21 are sprags 21a, 21b. The sprags 21a, 21b are tiltable within the plane shown in Fig. 3, and as shown enlarged in Fig. 4, a large diameter shaft A portion with a large diameter relative to the tilt center and a small diameter shaft B portion with a small diameter relative to the tilt center form a smoothly continuous cam shape. The sprags 21a, 21b are held in pockets 22, 27 formed in the inner cage 19 and the outer cage 20, and the orientations of the sprags 21a, 21b adjacent to each other in the circumferential direction are opposite to each other.

[0025] The length of the large diameter shaft A is larger than the radial gap between the outer peripheral surface of the output shaft 3 and the inner peripheral surface of the outer ring 4, and the length of the small diameter shaft B is smaller than the radial gap between the outer peripheral surface of the output shaft 3 and the inner peripheral surface of the outer ring 4. Therefore, by switching the tilt state of the sprags 21a, 21b, it is possible to switch between a standby state in which the sprags 21a, 21b are engaged between the output shaft 3 and the outer ring 4 and a non-standby state in which the sprags 21a, 21b are not engaged. Hereinafter, in the plane shown in FIG. 3, the sprag 21a that is in the standby state when a torque of a specified value or more is applied to the input shaft 2 in the counterclockwise direction is referred to as the first sprag 21a, and the sprag 21b that is in the standby state when a torque of a specified value or more is applied to the input shaft 2 in the clockwise direction is referred to as the second sprag 21b. The inner diameter side of each of the sprags 21a, 21b is biased by an elastic member 26 provided on the inner retainer 19 so as to tilt in the circumferential direction, more specifically, in the direction in which each of the sprags 21a, 21b moves toward the standby state.

[0026] The function of the rotation transmission device 1 will be described. When the torque input to the input shaft 2 is smaller than a specified value, as shown in Fig. 4, the rotation phase difference between the input shaft 2 and the output shaft 3 connected by the torsion bar 14 is small (Fig. 4 shows a state where there is no rotation phase difference), and the inner retainer 19 rotating with the input shaft 2 and the outer retainer 20 rotating with the output shaft 3 rotate at the same rotation speed. At this time, the first sprags 21a and the second sprags 21b held by both retainers 19, 20 are both in a disengaged state (non-standby state) between the output shaft 3 and the outer ring 4. When torque is input to the input shaft 2 in this state, the torque is transmitted only to the output shaft 3, and the torque is not transmitted to the outer ring 4.

[0027] When a counterclockwise torque equal to or greater than a specified value is input to the input shaft 2, the torque causes a twist in the torsion bar 14, and as shown in FIG. 5, a rotational phase difference α occurs between the input shaft 2 and the output shaft 3 connected by the torsion bar 14. At this time, a rotational phase difference α also occurs between the inner retainer 19 that rotates with the input shaft 2 and the outer retainer 20 that rotates with the output shaft 3, and the first sprag 21a and the second sprag 21b held by both retainers 19, 20 tilt around the tilting center. Then, the large-diameter shaft A side of the first sprag 21a engages between the output shaft 3 and the outer ring 4, resulting in a standby state. At this time, the second sprag 21b tilts in the opposite direction to maintain a non-standby state.

[0028] When counterclockwise torque is further input to the input shaft 2 while the first sprags 21a are in the standby state, causing a rotational phase difference β between the input shaft 2 (inner retainer 19) and the output shaft 3 (outer retainer 20), the switch pin 24 comes into contact with the inner surface of the insertion hole 13 formed in the output shaft 3 from the circumferential direction, as shown in Fig. 6. This causes torque to be transmitted from the input shaft 2 to the output shaft 3 via the switch pin 24, and also causes torque to be transmitted from the output shaft 3 to the outer ring 4 via the first sprags 21a.

[0029] In the above, we have described the case where counterclockwise torque is input to the input shaft 2. However, when clockwise torque is input to the input shaft 2, the large diameter shaft A side of the second sprag 21b engages between the output shaft 3 and the outer ring 4 and enters a standby state, and the first sprag 21a enters a non-standby state, which is the opposite to the above, but the basic operation is the same as above.

[0030] In the above-mentioned rotation transmission device 1, the inner retainer 19 is rotatable integrally with the input shaft 2, and the outer retainer 20 is rotatable integrally with the output shaft 3. Therefore, when a torque equal to or greater than a specified value is input to the input shaft 2 and the first sprag 21a or the second sprag 21b of the clutch section 5 is engaged, the torque input to the input shaft 2 can be transmitted to the output shaft 3 and the outer ring 4 while maintaining this engaged state.

[0031] Furthermore, since the rotation transmission device 1 uses sprags (the first sprags 21a and the second sprags 21b) as the engagement elements 21, the clutch portion 5 can be switched between an engaged state and a disengaged state with a simple configuration.

[0032] In addition, the above-mentioned rotation transmission device 1 has a switch pin 24 interposed between the input shaft 2 and the inner retainer 19, and when the first sprag 21a or the second sprag 21b is in an engaged state, the switch pin 24 abuts against the output shaft 3 from the circumferential direction, so that torque is transmitted from the input shaft 2 to the output shaft 3 via the switch pin 24.Therefore, the torque input to the input shaft 2 can be reliably transmitted to the output shaft 3, and the torque can be transmitted from the output shaft 2 to the outer ring 3 via the first sprag 21a or the second sprag 21b.

[0033] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0034] 2 Input member (input shaft) 3. First output member (output shaft) 4 Second output member (outer ring) 5 Clutch section 14 Torsion bar 19 Inner retainer 20 Outer cage 21 Engagement element 24 Switch pin 25 Convex α rotational phase difference

Claims

1. An input member (2) to which torque is input; a first output member (3) to which torque is transmitted from the input member (2) via a torsion bar (14), the first output member (3) being allowed to rotate relatively to the input member (2) on the same rotation axis as the input member (2); a second output member (4) rotatable by torque from the input member (2); a clutch portion (5) provided between the first output member (3) and the second output member (4); having the clutch portion (5) has an inner retainer (19), an outer retainer (20) provided radially outward of the inner retainer (19), and an engagement element (21) held by the inner retainer (19) and the outer retainer (20), The inner retainer (19) is rotatable integrally with the input member (2), and the outer retainer (20) is rotatable integrally with the first output member (3), When the torque input to the input member (2) is smaller than a specified value, the engaging element (21) held by both the retainers (19, 20) is disengaged between the first output member (3) and the second output member (4), and the torque input to the input member (2) is transmitted only to the first output member (3), while When the torque input to the input member (2) is equal to or greater than a specified value, the inner retainer (19) rotates ahead of the outer retainer (20), generating a rotational phase difference (α), and the engaging element (21) held by both retainers (19, 20) is engaged between the first output member (3) and the second output member (4), thereby transmitting the torque input to the input member (2) to both the first output member (3) and the second output member (4). This is a rotation transmission device.

2. 2. A rotation transmission device according to claim 1, wherein the engaging element (21) is a sprag.

3. 3. The rotation transmission device according to claim 1 or 2, further comprising a switch pin (24) interposed between the input member (2) and the inner retainer (19), wherein, when the engaging element (21) is in an engaged state, the switch pin (24) abuts against the first output member (3) from a circumferential direction, thereby transmitting torque from the input member (2) to the first output member (3).

4. 4. The rotation transmission device according to claim 3, wherein a convex portion (25) is formed on at least one side of the inner retainer (19) or the outer retainer (20), the convex portion (25) extending radially and extending to the other side of the inner retainer (19) or the outer retainer (20).

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