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 centering spring 9, 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 17, an outside cage 18, and an engagement element 19. The inside cage 17 and the outside cage 18 are rotatable integrally with the first output member 3 and the input member 2, respectively. When the torque is lower than a specified value, the engagement element 19 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 is higher, the engagement element 19 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 centering spring, 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 engaging element held by the inner retainer and the outer retainer, the inner retainer is rotatable integrally with the first output member, and the outer retainer is rotatable integrally with the input 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 outer retainer rotates ahead of the inner retainer, generating a rotational phase difference, and the engaging elements held by both retainers are engaged 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 first output member and the outer retainer rotatable integrally with the input 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 between the first output member and the outer cage, and when the engaging elements are in an engaged state, the switch pin abuts against the outer cage from the circumferential direction to transmit 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 including the switch pin, the second output member and the inner retainer can be rotated integrally by the switch pin. In this way, it is not necessary to form a flange on the inner retainer for integration with the second output member, and it is possible to reduce costs by simplifying the shape of the inner retainer and to achieve compactness by shortening the axial length.

[0013] In a configuration in which the second output member and the inner retainer are rotatable together by the switch pin, it is preferable that a convex portion extending in the radial direction and extending toward the other side of the inner retainer or the outer retainer is formed on at least one side of the inner retainer or the outer retainer, thereby ensuring a coaxial state between the inner retainer and the outer retainer.

[0014] In all of the above configurations, the input member and the outer cage can be configured to rotate together by a fixed member, which allows the shapes of the input shaft and the outer cage to be simplified, thereby reducing manufacturing costs. Effect of the Invention

[0015] 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]

[0016] [Figure 1] FIG. 1 is a cross-sectional view showing a first embodiment of a rotation transmission device according to the present invention. [Diagram 2] Cross-sectional view taken along line II-II in Figure 1. [Diagram 3] Cross-sectional view taken along line III-III in Figure 1 [Figure 4] Cross-sectional view of the main part when the clutch unit is not in the standby state [Diagram 5] Cross-sectional view of the main part near the switch pin when the clutch part is in standby state [Figure 6] Cross-sectional view of the main part near the switching spring when the clutch unit is in the standby state [Figure 7] A cross-sectional view of the main part near the switch pin when the input shaft is further rotated from the state shown in FIG. 5 and FIG. 6. [Figure 8] A cross-sectional view of the main part near the switching spring when the input shaft is further rotated from the state shown in FIG. 5 and FIG. 6. [Figure 9] FIG. 11 is a cross-sectional view showing a second embodiment of a rotation transmission device according to the present invention. [Figure 10] Cross-sectional view taken along line XX in Figure 9 [Figure 11] Cross-sectional view taken along line XI-XI in Figure 9 [Figure 12] FIG. 11 is a cross-sectional view showing a third embodiment of a rotation transmission device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A first embodiment of 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 outer ring and given the same reference number as the first output member 3), a second output member 4 (hereinafter referred to as an output shaft 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.

[0018] The input shaft 2 is a member to which torque is input, and has a through hole 6 formed at its axial center. An annular recess 7 is formed on the end face of the input shaft 2 facing the outer ring 3 and the output shaft 4, the recess 7 being coaxial with the axial center of the input shaft 2 and opening radially outward at a portion of the circumferential direction.

[0019] The outer ring 3 is a cylindrical member provided coaxially on the outer diameter side of the end of the input shaft 2. An engagement recess 8 is formed in a portion of the circumferential direction of the inner circumferential surface of the end of the outer ring 3 facing the input shaft 2. A centering spring 9 is provided between the input shaft 2 and the outer ring 3. As shown in FIG. 3, this centering spring 9 has an annular portion 10 having a slit in a portion of the circumferential direction, and two engagement portions 11 extending radially outward from both circumferential ends of the annular portion 10.

[0020] The annular portion 10 fits into the inner edge of an annular recess 7 formed in the input shaft 2, and the two engagement portions 11 engage with the inner surface of an engagement recess 8 formed in the outer ring 3. When no torque is input to the input shaft 2, the input shaft 2 and the outer ring 3 are held in a neutral position (where the opening of the annular recess 7 and the circumferential position of the engagement recess 8 coincide) shown in FIG. 3 by a centering spring 9. A bearing 12 is provided between the outer peripheral surface of the input shaft 2 and the inner peripheral surface of the outer ring 3, and relative rotation between the input shaft 2 and the outer ring 3 on the same rotation axis is permitted due to elastic deformation of the centering spring 9. A pin hole 13 extending radially is formed in the outer ring 3. A switch pin 14 is inserted into the pin hole 13.

[0021] The output shaft 4 is a cylindrical member disposed coaxially with the input shaft 2 and having a through hole 15 formed at its axis. A bearing 16 is provided between the inner peripheral surface of the outer ring 3 and the outer peripheral surface of the output shaft 4, allowing relative rotation between the outer ring 3 and the output shaft 4. The through holes 6, 15 formed in the input shaft 2 and the output shaft 4, respectively, communicate with each other in the axial direction, and it is also possible to pass cables or the like through the through holes 6, 15. Note that since the through holes 6, 15 are not related to the function of the rotation transmission device 1 itself, the input shaft 2 and the output shaft 4 may be solid shaft bodies without the through holes 6, 15 formed therein.

[0022] The clutch portion 5 has an inner retainer 17, an outer retainer 18 provided radially outside the inner retainer 17, and an engaging element 19 held by the inner retainer 17 and the outer retainer 18, and is provided between the inner surface of the outer ring 3 and the outer surface of the output shaft 4.

[0023] The inner cage 17 is a cylindrical member in which a plurality of pockets 20 (eight in this embodiment) are formed at predetermined angular intervals in the circumferential direction, as shown in Fig. 2. A flange portion 21 extending radially outward is formed on one axial end of the inner cage 17, as shown in Fig. 1. The outer peripheral surface of the flange portion 21 fits into the inner peripheral surface of the outer ring 3, so that the outer ring 3 and the inner cage 17 rotate together.

[0024] 2, the outer retainer 18 is a cylindrical member in which pockets 22 are formed in the circumferential direction at the same predetermined angular intervals and in the same number as the inner retainer 17. In this embodiment, the outer retainer 18 is formed integrally with the input shaft 2, and the input shaft 2 and the outer retainer 18 rotate integrally. An elastic member 23 is provided on the circumferential inner surface of the pockets 22 formed in the outer retainer 18, which biases the engagement elements 19 held in the pockets 22 in the circumferential direction. In this embodiment, a leaf spring is used as the elastic member 23, but other types of elastic members 23, such as a coil spring, can also be used.

[0025] 2, a radially extending insertion hole 24 is formed at one circumferential location of the outer retainer 18. The circumferential width of the insertion hole 24 is formed larger than the outer diameter of the switch pin 14. The end portion of the switch pin 14 that is inserted into the pin hole 13 formed in the outer ring 3 and protrudes toward the inner diameter side is positioned within the insertion hole 24.

[0026] The engaging elements 19 are sprags 19a, 19b. The sprags 19a, 19b are tiltable within the plane shown in Fig. 2, 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 19a, 19b are held in pockets 20, 22 formed in the inner cage 17 and the outer cage 18, and the orientations of the sprags 19a, 19b adjacent to each other in the circumferential direction are opposite to each other.

[0027] The length of the large diameter shaft A is larger than the radial gap between the inner peripheral surface of the outer ring 3 and the outer peripheral surface of the output shaft 4, and the length of the small diameter shaft B is smaller than the radial gap between the inner peripheral surface of the outer ring 3 and the outer peripheral surface of the output shaft 4. Therefore, by switching the tilt state of the sprags 19a, 19b, it is possible to switch between a standby state in which the sprags 19a, 19b are engaged between the outer ring 3 and the output shaft 4 and a non-standby state in which the sprags 19a, 19b are not engaged. Hereinafter, in the plane shown in FIG. 2, the sprag 19a 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 19a, and the sprag 19b 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 19b. The outer diameter side of each sprag 19a, 19b is biased by an elastic member 23 provided on the outer retainer 18 so as to tilt in the circumferential direction, more specifically, in the direction in which each sprag 19a, 19b moves toward the standby state.

[0028] 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 outer ring 3 connected via the centering spring 9 is small (FIG. 4 shows a state where there is no rotation phase difference), and the outer retainer 18 rotating integrally with the input shaft 2 and the inner retainer 17 rotating integrally with the outer ring 3 rotate at the same rotation speed. At this time, the first sprag 19a and the second sprag 19b held by both retainers 17, 18 are both in a disengaged state (non-standby state) between the outer ring 3 and the output shaft 4. When torque is input to the input shaft 2 in this state, the torque is transmitted only to the outer ring 3, and the torque is not transmitted to the output shaft 4.

[0029] When a counterclockwise torque equal to or greater than a specified value is input to the input shaft 2, the centering spring 9 is deformed by the torque so that the two engaging portions 11 approach each other, as shown in Figs. 5 and 6, and a rotational phase difference α occurs between the input shaft 2 and the outer ring 3 connected via the centering spring 9. At this time, a rotational phase difference α also occurs between the outer retainer 18, which rotates integrally with the input shaft 2, and the inner retainer 17, which rotates integrally with the outer ring 3, and the first sprag 19a and the second sprag 19b, which are held by both retainers 17 and 18, tilt around the tilting center. Then, the large-diameter shaft A side of the first sprag 19a is engaged between the outer ring 3 and the output shaft 4, resulting in a standby state. At this time, the second sprag 19b tilts in the opposite direction to maintain a non-standby state.

[0030] When counterclockwise torque is further input to the input shaft 2 while the first sprags 19a are in the standby state, causing a rotational phase difference β between the input shaft 2 (outer retainer 18) and the outer ring 3 (inner retainer 17), the switch pin 14 comes into contact with the inner surface of the insertion hole 24 formed in the outer retainer 18 from the circumferential direction, as shown in Figures 7 and 8. As a result, torque is transmitted from the input shaft 2 to the outer ring 3 via the switch pin 14, and torque is transmitted from the outer ring 3 to the output shaft 4 via the first sprags 19a.

[0031] 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 19b engages between the outer ring 3 and the output shaft 4 to enter a standby state, and the first sprag 19a enters a non-standby state, which is the opposite to the above, but the basic operation is the same as above.

[0032] In the above-mentioned rotation transmission device 1, the outer retainer 18 is rotatable integrally with the input shaft 2, and the inner retainer 17 is rotatable integrally with the outer ring 3. Therefore, when a torque equal to or greater than a specified value is input to the input shaft 2 and the first sprag 19a or the second sprag 19b of the clutch section 5 is engaged, the torque input to the input shaft 2 can be transmitted to the outer ring 3 and the output shaft 4 while maintaining this engaged state.

[0033] Furthermore, since the rotation transmission device 1 uses sprags (the first sprags 19a and the second sprags 19b) as the engagement elements 19, the clutch portion 5 can be switched between an engaged state and a disengaged state with a simple configuration.

[0034] In addition, the above-mentioned rotation transmission device 1 is configured to have a switch pin 14 on the outer ring 3, and when the first sprags 19a or the second sprags 19b are engaged, the switch pin 14 abuts against the outer retainer 18, which rotates integrally with the input shaft 2, from the circumferential direction, so that torque is transmitted from the input shaft 2 to the outer ring 3 via the switch pin 14.Therefore, the torque input to the input shaft 2 can be reliably transmitted to the outer ring 3, and the torque can be transmitted from the outer ring 3 to the output shaft 4 via the first sprags 19a or the second sprags 19b.

[0035] A second embodiment of a rotation transmission device 1 according to the present invention is shown in Figures 9 to 11. The rotation transmission device 1 according to the second embodiment has a basic configuration in common with the rotation transmission device 1 according to the first embodiment, but differs in the configuration relating to torque transmission between the outer ring 3 and the inner cage 17.

[0036] More specifically, the configuration according to the second embodiment differs from the configuration according to the first embodiment in that a pin hole 25 extending in the radial direction is formed in the inner cage 17, and a common switch pin 14 is inserted through an insertion hole 24 formed in the outer cage 18 into the pin holes 13, 25 formed in the outer ring 3 and the inner cage 17, respectively. According to the configuration according to the second embodiment, since the outer ring 3 and the inner cage 17 can be rotated together via the switch pin 14, it is not necessary to form a flange portion 21 at the axial end of the inner cage 17 and fit it to the outer ring 3 to integrate them, as in the configuration according to the first embodiment. Therefore, by simplifying the shape of the inner cage 17 (almost cylindrical), an inexpensive processing method such as press processing can be adopted. In addition, since the axial length is shortened by the amount of the flange portion 21, it is possible to achieve a compact design.

[0037] In this way, when the outer ring 3 and the inner retainer 17 are rotated together via the switch pin 14, the inner retainer 17 is supported only by the switch pin 14, and the inner retainer 17 may become misaligned with the outer retainer 18 (input shaft 2) and the outer ring 3. Therefore, in the configuration according to the second embodiment, a plurality of protrusions 26 extending radially outward toward the outer retainer 18 are formed on the outer peripheral surface of the inner retainer 17, thereby partially reducing the radial gap between the two retainers 17, 18. In this way, the protrusions 26 formed on the inner retainer 17 are guided by the inner peripheral surface of the outer retainer 18, and the inner retainer 17, 18 can be rotated relative to one another while maintaining the coaxial relationship between the inner retainer 17, the outer retainer 18 (input shaft 2), and the outer ring 3.

[0038] In this embodiment, the protrusions 26 are formed on the outer peripheral surface of the inner cage 17, but the same effect can be obtained by forming the protrusions 26 on the inner peripheral surface of the outer cage 18. Also, the protrusions 26 can be formed on both the outer peripheral surface of the inner cage 17 and the inner peripheral surface of the outer cage 18. Note that the shape, position, number, etc. of the protrusions 26 shown in Fig. 10 are merely examples and can be changed as appropriate.

[0039] A third embodiment of the rotation transmission device 1 according to the present invention is shown in Fig. 12. The rotation transmission device 1 according to the third embodiment has a basic configuration in common with the rotation transmission device 1 according to the second embodiment, but differs in the configuration related to the transmission of torque between the input shaft 2 and the outer cage 18.

[0040] More specifically, the configuration according to the third embodiment differs from the configuration according to the second embodiment in that the input shaft 2 and the outer retainer 18 are formed as separate members, and the input shaft 2 and the outer retainer 18 are integrated by inserting a common fixing member 29 (fixing pin) into a fixing hole 27 extending in the radial direction formed in the input shaft 2 and a fixing hole 28 extending in the radial direction formed in the outer retainer 18. According to the configuration of the third embodiment, the shape of the outer retainer 18 is simplified (almost cylindrical) compared to the case where the input shaft 2 and the outer retainer 18 are integrally molded, and an inexpensive processing method such as press processing can be adopted.

[0041] 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]

[0042] 2 Input member (input shaft) 3 First output member (outer ring) 4 Second output member (output shaft) 5 Clutch section 9 Centering Spring 14 Switch pin 17 Inner retainer 18 Outer cage 19 Engagement element 26 Convex 29 Fixing member 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 centering spring (9), the first output member (3) being allowed to rotate relatively about 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 (17), an outer retainer (18) provided radially outward of the inner retainer (17), and an engagement element (19) held by the inner retainer (17) and the outer retainer (18), The inner retainer (17) is rotatable integrally with the first output member (3), and the outer retainer (18) is rotatable integrally with the input member (2), When the torque input to the input member (2) is smaller than a specified value, the engaging element (19) held by both the retainers (17, 18) 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 outer retainer (18) rotates ahead of the inner retainer (17), generating a rotational phase difference (α), and the engaging element (19) held by both retainers (17, 18) 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 said engaging members (19) are sprags.

3. 3. A rotation transmission device according to claim 1 or 2, further comprising a switch pin (14) between the first output member (3) and the outer retainer (18), and when the engaging element (19) is in an engaged state, the switch pin (14) abuts against the outer retainer (18) 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 the second output member (4) and the inner retainer (17) are rotatable together with each other by the switch pin (14).

5. 5. The rotation transmission device according to claim 4, wherein a protrusion (26) is formed on at least one side of the inner retainer (17) or the outer retainer (18), the protrusion (26) extending radially and extending to the other side of the inner retainer (17) or the outer retainer (18).

6. 6. The rotation transmission device according to claim 1, wherein the input member (2) and the outer retainer (18) are rotatable together with each other via a fixed member (29).

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