Reverse input blocking clutch

Abstract

To provide a reverse input cut-off clutch capable of increasing clutch strength, achieving compactness, and having excellent transmission efficiency.SOLUTION: The cam member is interposed between the first brake member and the second brake member, the rotational motion of the output member is transmitted to the cam member by the reverse input of torque to the output member, the first brake member and the second brake member are moved in a direction away from each other in the radial direction, the first brake member and the second brake member are pressed against the stationary member, and the transmission of torque from the output member to the input member is blocked. The output member has an output shaft portion disposed on the same axis as the axis of the input shaft portion of the input member, and a pair of arm portions extending in opposite directions from the output shaft portion in a radial direction, the cam member is connected to a radially outer end portion of one arm portion of the output member via a support shaft portion, and a concavo-convex fitting structure is provided between a radially outer end portion of the other arm portion of the output member and a side opposite to the support shaft portion of the cam member, and an amount of swinging about the support shaft portion of the output member is restricted in a fitted state of the concavo-convex fitting structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reverse input disconnecting clutch. [Background technology]

[0002] As shown in Fig. 19, the reverse input cutoff clutch is a clutch that transmits the rotation of the input member 2 to the output member 3 when input torque is applied, and prevents the input member 2 from rotating in response to reverse input torque. Such a reverse input cutoff clutch is described, for example, in Patent Document 1.

[0003] In the reverse input cutoff clutch described in Patent Document 1, when torque is reversely input to the output member 3, the output member 3 moves a pair of engaging members (engagements) 5, 5 radially outward, thereby pressing the pressing surfaces 11, 11 of the engaging members 5, 5 against the pressed surface 10 (inner diameter surface consisting of a cylindrical surface) of the pressed member 4, thereby cutting off the torque. Furthermore, when torque is input to the input member 2, the pair of engaging members 5, 5 move radially inward, thereby moving the pressing surfaces 11, 11 of the engaging members 5, 5 away from (separating from) the pressed surface 10 of the pressed member 4. The torque input to the input member 2 is transmitted to the output member 3 via the engaging members 5, 5. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 172558 Summary of the Invention [Problem to be solved by the invention]

[0005] In the device described in Patent Document 1, a gap is provided between the output member 3 and the engaging members 5, 5 to allow the engaging members 5, 5 to separate from the pressed member 4. In other words, there is a so-called backlash (play). The size of the backlash is determined by the size of the gap and the distance from the center of rotation of the contact portion X of the output member 3 and the engaging members 5, 5. In this case, the distance r (see FIG. 19) from the center of rotation O of the contact portion X is short, and the backlash that occurs is large. If the "backlash" is large, it may cause abnormal noise.

[0006] That is, in the clutch described in Patent Document 1, when rotational torque is input to the input member 2, the input-side engaging portion 7 rotates inside the input-side engaged portion 12 in the rotational direction of the input member 2. Then, the radially inner surface of the input-side engaging portion 7 presses the radially inner portion of the inner surface of the input-side engaged portion 12 radially inward. In this case, each engaging element 5 elastically contracts the pair of springs 18, moving in a direction away from the pressed surface 10. Then, the output-side engaged surface 16 of each engaging element 5 comes into surface contact with both sides of the output-side engaging portion 9 of the output member 3 in the lateral direction. As a result, the rotational torque input to the input member 2 is transmitted to the output member 3 via the pair of engaging elements 5.

[0007] When a rotational torque is reversely input to the output member 3, the reverse input cutoff clutch 1 moves each of the engaging elements 5 in a direction approaching the pressed surface 10, regardless of the rotational direction of the output member 3. Then, the rotational torque reversely input to the output member 3 is completely cut off and not transmitted to the input member 2, or only a portion of the rotational torque reversely input to the output member 3 is transmitted to the input member 2, with the remainder being cut off. In other words, when a rotational torque is reversely input to the output member 3, the output-side engaging portion 9 rotates in the rotational direction of the output member 3, inside the pair of output-side engaged portions 13. Then, the corners of the output-side engaging portion 9 press the output-side engaged surface 16 radially outward. As a result, each of the engaging elements 5 moves in a direction approaching the pressed surface 10, and the engaging elements 5 move radially outward, away from each other, based on their engagement with the output member 3.

[0008] In order to cut off the reverse input, the reverse input torque must be smaller than the brake torque. In other words, the following equation 1 must be satisfied:

number

[0009] In this case, it is necessary to reduce the distance r from the center of rotation O to the contact point X between the output member 2 and the engaging member 5. However, reducing the distance r increases the load acting on the output member 3, resulting in durability problems. Furthermore, to satisfy the relationship in equation (1), it is necessary to increase the distance R (see FIG. 19), where R is the distance from the center of rotation O to the contact point C (see FIG. 19) between the engaging member 5 and the pressed member 4. However, increasing the distance R increases the outer diameter of the reverse input cutoff clutch, making it impossible to make it compact, making it difficult to install, and increasing its weight.

[0010] In view of the above problems, the present invention provides a reverse input cutoff clutch that has increased clutch strength, can be made compact, and has excellent transmission efficiency. [Means for solving the problem]

[0011] The reverse input cutoff clutch of the present invention is a reverse input cutoff clutch having an input member to which torque is input, an output member to which torque is output, first and second braking members capable of reciprocating in the radial direction, and a stationary member arranged radially outside the first and second braking members, and equipped with a bearing that rotatably supports the output member, and further comprising a separating movement mechanism that moves the first and second braking members in a direction toward each other in the radial direction when torque is input to the input member, and moves the first and second braking members in a direction away from the stationary member, a transmission mechanism that transmits the torque input to the input member to the output member while the first and second braking members are away from the stationary member, and a cam member interposed between the first and second braking members, and a transmission mechanism that transmits the torque input to the output member When torque is input in reverse, the rotational motion is transmitted to the cam member, causing the first and second braking members to move radially away from each other, and the first and second braking members are pressed against the stationary member, thereby blocking the transmission of torque from the output member to the input member. The output member has an output shaft portion disposed coaxially with the axis of the input shaft portion of the input member, and a pair of arms extending in opposite radial directions from the output shaft portion. The cam member is connected to the radially outer diameter side end of one of the arms of the output member via a support shaft portion, and a concave-convex fitting structure is provided between the radially outer diameter end of the other arm portion of the output member and the side opposite the support shaft portion of the cam member, and when the concave-convex fitting structure is engaged, the amount of oscillation of the output member about the support shaft portion is limited.

[0012] According to the reverse input cutoff clutch of the present invention, when torque is input to the input member, the pair of brake members separate from the stationary member. In this separated state, the torque input to the input member is transmitted to the output member, causing the output member to rotate. Furthermore, when torque is input reversely to the output member, the cam member rotates, causing the first and second brake members to separate relatively. This presses the first and second brake members against the stationary member, blocking the transmission of torque from the output member to the input member. The first and second brake members separate relatively by rotation of the cam member interposed between the first and second brake members. At this time, the cam member restricts the first and second brake members from approaching each other, effectively preventing the pair of brake members from separating from the stationary member. Furthermore, when the first and second brake members are relatively separated, the end of the cam member facing the first brake member contacts the first brake member, the end of the cam member facing the second brake member contacts the second brake member, and if the end of the cam member facing the first brake member rotates counterclockwise, the end of the cam member facing the second brake member also rotates counterclockwise. In this case, the end of the cam member facing the first brake member presses the first brake member toward the opposite side of the second brake member, and the end of the cam member facing the second brake member presses the second brake member toward the opposite side of the first brake member. Therefore, by setting the distance between the first contact portion on the cam member side that contacts the first brake member and the second contact portion on the cam member side that contacts the second brake member relatively long, the angle of rotation of the cam member between the first and second brake members is reduced, thereby reducing backlash of the output member. Furthermore, the load acting on the cam member can be reduced, thereby increasing the strength of the clutch.

[0013] Furthermore, even if the distance from the contact point between one braking member and the cam member to the rotation center O is long, the reverse input torque can be made smaller than the braking torque without increasing the distance from the rotation center O to the braking member and the stationary member. As a result, the outer diameter of this clutch does not need to be large.

[0014] Furthermore, a recessed / protruding fitting structure is provided between the radially outer end of the other arm portion of the output member and the side opposite the support shaft portion of the cam member, and by limiting the amount of swing of the output member about the support shaft portion when the recessed / protruding fitting structure is engaged, a reduction means is provided to reduce the surface pressure generated at the contact portion of the bearing that rotatably supports the output member, thereby preventing losses due to wear at the contact portion and preventing a decrease in transmission efficiency.In addition, the reduction means does not need to be complicated, and the configuration can be simplified.

[0015] The concave-convex fitting structure is preferably composed of a protruding shaft portion and a hole portion into which the protruding shaft portion fits, and the hole portion is preferably an elongated hole that is long in the direction in which the protruding shaft portion rotates around the support shaft portion. By configuring in this way, the recess-projection fitting structure can be easily configured.

[0016] The cam member can have a cam main body portion that extends radially and has one radial end connected to the radial outer diameter side end of one of the arm portions of the output member, and a protrusion portion that is provided on the cam main body portion and arranged between the first braking member and the second braking member, and can be configured so that when torque is input in reverse to the output member, the connecting portion of one of the arm portions swings around the output shaft portion of the output member, and the first contact portion and second contact portion of the protrusion press against the pressed surfaces of the braking members of the first braking member and the second braking member, respectively, and move in a direction that moves them radially away from each other.

[0017] With this configuration, the output member has an output shaft portion that is coaxial with the input shaft portion of the input member, allowing the output member to rotate stably without wobbling when torque is input to the input member. Furthermore, when torque is input in reverse to the output member, the connecting portion of the arm portion of the cam main body swings around the output shaft portion of the output member, causing the pair of first and second contact portions of the protrusion to press the first and second brake members, respectively, and move in a direction away from each other in the radial direction. This allows the first and second brake members to slide stably in a direction away from each other, i.e., radially outward. When the first and second brake members slide in a direction away from each other, they are pressed against the stationary member, thereby blocking the transmission of torque from the output member to the input member. This allows the state in which torque transmission to the input member is blocked to be stably achieved.

[0018] It is preferable that an intermediate portion between the first contact portion and the second contact portion is disposed at a position radially spaced from the rotation center of the input shaft of the input member, and that the first contact portion and the second contact portion of the cam member have different distances to the rotation center of the input shaft of the input member.Furthermore, it is preferable that the first braking member and the second braking member swing about one radial end side, and that the swing center is disposed on the opposite side of the intermediate portion between the first contact portion and the second contact portion with respect to a perpendicular line that passes through the rotation center of the input shaft and is perpendicular to the pressed surface of the braking member.

[0019] This increases the frictional force at the contact portion (contact surface) between the stationary member and one of the braking members, thereby enabling a self-amplifying increase in braking torque. This allows the braking member to effectively generate a torque transmission blocking force to the input member. Furthermore, by arranging the connecting portion between the arm portion of the output member and the cam member radially outward from the center of the protrusion of the cam member, the rotation angle of the output member at the position where rotation of the cam member is restricted is reduced, reducing backlash in the output member and enabling stable torque blocking.

[0020] The first braking member and the second braking member may be configured such that opposing protrusions are provided on one radial end of the first braking member and one radial end of the second braking member, the opposing surfaces of the protrusions being cylindrical, and the protrusions come into contact with each other when torque is input to the input member, and the first braking member and the second braking member swing toward each other around the protrusion contact point as a fulcrum, causing the first braking member and the second braking member to move away from the stationary member, and the first braking member and the second braking member can be configured to be rotatable about a support shaft. Furthermore, the protrusion of the cam member may be configured as a pair of convex portions spaced apart in the radial direction. Furthermore, it is preferable that the input member and the output member are rotatably supported relative to the stationary member. [Effects of the Invention]

[0021] In the present invention, the backlash of the output member can be reduced, the load acting on the cam member can be reduced, the strength of the clutch can be increased, and further, transmission efficiency is excellent. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 2 is a simplified exploded perspective view of the reverse input cutoff clutch according to the present invention. [Figure 2] FIG. 2 is a vertical cross-sectional view of the reverse input cutoff clutch shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] This is a simplified diagram seen from the output side. [Figure 5] FIG. 1 is a simplified diagram seen from the output side where torque is input to an input member. [Figure 6] FIG. 10 is a simplified diagram viewed from the output side in a state where torque is reversely input to the output member. [Figure 7] FIG. 10 is a simplified diagram viewed from the input side in a state where torque is reversely input to the output member. [Figure 8] FIG. 10 is a simplified diagram seen from the input side showing a state in which torque is reversely input to the output member, illustrating the dimensional and angular relationships of the various members. [Figure 9]FIG. 10 is a simplified diagram seen from the output side showing a state in which torque is reversely input to the output member, illustrating the dimensional and angular relationships of the various members. [Figure 10] FIG. 10 is a simplified cross-sectional view showing a first modified example of a reverse input cutoff clutch. [Figure 11] FIG. 10 is a simplified exploded perspective view of a comparative example of a reverse input cutoff clutch. [Figure 12] FIG. 12 is a vertical cross-sectional view of the reverse input cutoff clutch shown in FIG. [Figure 13] FIG. 13 is a cross-sectional view taken along line AA in FIG. 12. [Figure 14] 12 is a simplified diagram of the reverse input disconnect clutch shown in FIG. 11 as viewed from the output side. [Figure 15] 12 is a simplified diagram of the reverse input disconnect clutch shown in FIG. 11 as viewed from the output side where torque is input to the input member. [Figure 16] 12 is a simplified diagram of the reverse input cutoff clutch shown in FIG. 11 as viewed from the input side when torque is reversely input to the output member. [Figure 17] 12A and 12B show a state in which torque is reversely input to the output member of the reverse input cutoff clutch shown in FIG. 11, where (a) is a cross-sectional view and (b) is an enlarged cross-sectional view of a main part. [Figure 18] 12 is a simplified diagram seen from the output side for explaining a problem that occurs when torque is reversely input to the output member of the reverse input cutoff clutch shown in FIG. 11. FIG. [Figure 19] 1 is a simplified diagram showing a conventional reverse input cutoff clutch in a state where a reverse torque is input to an output member. [Figure 20] FIG. 20 is an enlarged view of a main part of FIG. 19. DETAILED DESCRIPTION OF THE INVENTION

[0023] First, a comparative example shown in Figs. 11 to 17 will be described. Fig. 11 shows a simplified perspective view of a reverse input cutoff clutch according to the present invention, Fig. 12 shows a longitudinal cross-sectional view of the reverse input cutoff clutch, Fig. 13 shows a cross-sectional view taken along line AA in Fig. 12, and Fig. 14 is a simplified view of the reverse input cutoff clutch as seen from the output side. The reverse input cutoff clutch is a reverse input cutoff clutch having an input member 21 to which torque is input, an output member 22 to which torque is output, a pair of first and second braking members 23A and 23B capable of reciprocating in the radial direction, and a stationary member 24 disposed radially outward so as to cover the first and second braking members 23A and 23B. Here, the radial direction refers to the direction perpendicular to the rotation axis. The device also includes a separating mechanism M1 that moves the pair of first and second braking members 23A, 23B in a direction radially approaching each other when torque is input to the input member 21, thereby moving the first and second braking members 23A, 23B in a direction away from the stationary member 24, and a transmission mechanism M2 that transmits the torque input to the input member 21 to the output member when the first and second braking members 23, 23 are away from the stationary member 24.

[0024] The input member 21 includes an input shaft portion 21a and a main body portion 21b connected to one end surface of the input shaft portion 21a. The main body portion 21b has a disk portion 27 and a pair of bulging portions 28A, 28B provided on the opposite side of the disk portion 27 from the input shaft portion. The bulging portions 28A, 28B are provided at positions 180° opposite each other with respect to the center of the disk portion 27. The bulging portions 28A, 28B are provided on the outer peripheral edge side of the disk portion 27, with their inner diameter portions formed as flat surfaces 29a, 29a facing each other and their outer diameter surfaces formed as arcuate surfaces 29b, 29b integrated with the outer peripheral edge of the disk portion 27.

[0025] The output member 22 has an output shaft portion 22a and an arm portion 22b extending radially outward from the axial end (the end on the input member side) of the output shaft portion 22a, and is connected to a cam member 30. Here, the axial direction refers to the direction along the central axis of the output shaft portion 22a, i.e., the direction of the center line of rotation when an object rotates. The cam member 30 has a flat body portion 30a extending radially and a protrusion portion 30b provided on the end surface of the body portion 30a facing the input member. The protrusion portion 30b has a rectangular parallelepiped shape and is not provided on one radially outer side of the body portion 30a. The arm portion 22b of the output member 22 is connected to the cam body portion 30a of the cam member 30 via a support shaft portion 31, which constitutes a connecting portion, with the arm portion 22b of the output member 22 and the back side (the side opposite the input member) of the cam body portion 30a of the cam member 30 overlapping each other. In this case, the output member 22 and the cam member 30 are rotatable via the support shaft portion 31, and the output member 22 and the cam member 30 swing around the support shaft portion 31. Through holes 31a, 31a are provided in the arm portion 22b and the cam main body portion 30a, and the support shaft portion 31 is fitted into these through holes 31a, 31a.

[0026] The braking members 23A, 23B each have a flat plate-shaped main body 32 and a protrusion 33 protruding inward from one longitudinal end of the main body 32. When placed over the protrusion 33, the braking members 23A, 23B are rotatable via a support shaft 34 that forms the center of oscillation, and the braking members 23A, 23B oscillate around the support shaft 34. When the braking members 23A, 23B are connected, a gap S1 (see FIG. 16) is provided between the main bodies 32, and the protrusion 30b of the cam member 30 is fitted into this gap S1. Each protrusion 33 is provided with a through hole 33a, into which the support shaft 34 is fitted.

[0027] Furthermore, the braking members 23A, 23B are interposed between the bulging portions 28A, 28B of the input member 21. When torque is input to the input member 21 in the direction of arrow A1 shown in FIG. 15, the input shaft portion 21a of the input member 21 rotates about its axis in the direction of arrow A1, and the pair of bulging portions 28A, 28B also rotate about the axis of the input shaft portion 21a. As a result, one end (the lower end in the illustrated example) of the flat surface 29a on the inner diameter of the first bulging portion 28A presses the braking member 23A inward, and the other end (the upper end in the illustrated example) of the flat surface 29a on the inner diameter of the second bulging portion 28B presses the braking member 23B inward. As a result, the braking members 23A, 23B come relatively close to each other.

[0028] 11 and 12, the stationary member 24 is made up of a first frame 35 and a second frame 36. The first frame 35 is made up of a disk portion 35a and a short cylindrical peripheral wall portion 35b, with an axial hole 37 formed in the disk portion 35a, and the second frame 36 is disk-shaped and also has an axial hole 38 formed therein. A circumferential cutout portion 36a is formed in the outer end of the inner surface of the second frame 36, and the first frame 35 and the second frame 36 are integrated with each other in a state where the end of the peripheral wall portion 35b of the first frame 35 is fitted into this circumferential cutout portion 36a. Therefore, the stationary member 24 has an accommodation chamber S (see FIG. 12, etc.) formed therein in which the braking members 23, 23, the cam member 30, etc. are accommodated.

[0029] With the arm portion 22b of the output member 22 housed in the housing chamber S of the stationary member 24, the output shaft portion 22a is supported in the shaft hole 37 via a bearing 40, and with the main body portion 21b of the input member 21 housed in the housing chamber S, the input shaft portion 21a is supported in the shaft hole 38 via a bearing 41. Also, as shown in Figure 12, the input shaft portion 21a of the input member 21 and the output shaft portion 22a of the output member 22 are arranged on the same axis.

[0030] The longitudinal outer end faces of the braking members 23A, 23B are formed as arcuate contact surfaces 42, 42, and the curvature of the contact surface 42 is smaller than the curvature of the inner diameter surface 43 of the peripheral wall portion 35b of the stationary member 24.

[0031] Next, the operation of the reverse input cutoff clutch configured as described above will be described. First, the case where torque is input to the input member 21 will be described. When torque is input to the input member 21, that is, when a rotational force in the direction of arrow A1 is applied as shown in FIG. 15, the braking members 23A and 23B move closer to each other in the radial direction, as described above. This movement causes the abutment surface 42 of the braking member 23 to move away from the abutted surface 43a of the stationary member 24. In this spaced state, the input member 21 rotates around its axis (the axis of the input shaft portion 21a). This rotation causes the braking members 23 to rotate. Furthermore, the cam member 30 sandwiched between the braking members 23 rotates around the axis of the input member 21. When the cam member 30 rotates, the output member 22 connected to the cam member 30 rotates around the axis of the output shaft portion 22a. That is, when torque is input to the input member 21, the torque is transmitted to the output member 22, and the output shaft portion 22a of the output member 22 rotates.

[0032] For this reason, the present reverse input disconnecting clutch has a separation movement mechanism M1 that moves the first and second braking members 23A, 23B in a direction separating them from the stationary member 24, and the separation movement mechanism M1 can be configured by a pair of bulging portions 28A, 28B of the disk portion 27.

[0033] Furthermore, this reverse input cutoff clutch is provided with a transmission mechanism M2 that transmits torque input to the input member 21 to the output member 22 when the first and second braking members 23A, 23B are separated from the stationary member 24, and this transmission mechanism M2 can be composed of the first and second braking members 23A, 23B, a cam member 30, etc.

[0034] However, if torque is input in reverse to the output member 22, the torque is not transmitted to the input member 21. In other words, if torque is input (reverse input) to the output member 22, the output member 22 rotates. When the output member 22 rotates, the support shaft 31 connecting the cam member 30 and the output member 22 rotates around the axis of the output shaft 22a of the output member 22. Therefore, the cam member 30 rotates around the axis of the output shaft 22a of the output member 22, with the support shaft 31 as the oscillating rotation axis, as shown in FIG. 7. Therefore, the cam member 30 presses each of the pair of braking members 23, 23 that are connected by the support shaft 34 so as to be rotatable relative to each other, toward the stationary member 24. In other words, as shown in FIGS. 6 and 7, the protrusion 30b interposed between the pair of braking members 23, 23 rotates around the axis O, with the support shaft 31 as the oscillating rotation axis. The axis O is the axis of the input shaft portion 21a of the input member 21 and the axis of the output shaft portion 22b of the output member 22, which are coaxially aligned.

[0035] When the support shaft 31 rotates around the axis O, an edge X1 on the support shaft side of the side surface of the protrusion 30b facing the first braking member presses the first braking member 23A toward the stationary member 24, and an edge X2 on the anti-support shaft side of the side surface of the protrusion 30b facing the second braking member presses the second braking member 23B toward the stationary member 24. As a result, torque transmission is interrupted by a frictional force generated between the abutting surface 42 of the braking member 23 and the abutted surface 43a of the stationary member 24. Here, the midpoint position of the line segment connecting the edge X1 (first contact portion) and the edge X2 (second contact portion) is defined as an intermediate portion (center O1, described below).

[0036] However, in order to block and stop the reverse input, the relationship of the forces acting on one of the braking members 23 (in this case, the first braking member 23A) needs to satisfy T < T´, where T is the reverse input torque and T´ is the braking torque. In this case, among the respective contact portions X1 and X2 between the cam member 30 and the pair of braking members 23A and 23B, the distance from the contact portion X1 close to the rotation center O to the rotation center is denoted as r (see FIGS. 17(a) and (b)), the distance from the contact portion X2 far from the rotation center O to the rotation center is denoted as r´, the distance from the rotation center O to the braking member 23 and the stationary member 24 is denoted as R, the friction coefficient between the contact portions X1 and X2 of the cam member 30 and the braking member 23 is denoted as μ, and the friction coefficient between the contact portion C of the braking member 23 and the stationary member 24 is denoted as μ´. In this case, a tangential force Ft orthogonal to the straight line connecting the contact portion X1 and the rotation center O acts on the contact portion X1, and among the angles formed by the direction in which the tangential force Ft acts and the braking member pressed surface 23a, the acute angle side angle is denoted as β (see FIG. 17(b)). The braking member pressed surface 23a is the surface of the braking member 23 that faces the protrusion 30b of the cam member 30 and is pressed by the protrusion 30b. Let the angle formed by the tangent Y at the contact portion C between the braking member 23 and the stationary member 24 and the perpendicular line P passing through the rotation center O and orthogonal to the braking member pressed surface 23a be α. Therefore, in order to satisfy the above-mentioned T < T´, it is necessary to satisfy the formula shown in Equation 2 below.

Equation

[0037] Meanwhile, one of the brake members 23A, which comes into contact with the cam member 30 at X1, is pressed against the stationary member 24 by the cam member 30, and the brake member 23A comes to a standstill by satisfying the reverse input blocking condition of Equation 2. The other brake member 23B, which comes into contact with the cam member 30 at X2, which is farther from the support shaft 31 than X1, is pressed against the stationary member 24 by the cam member 30. However, since r' is large and does not satisfy the reverse input blocking condition of Equation 2, a rotational torque acts in the same direction as the reverse input torque acting on the output member 22, and this torque is transmitted to the support shaft 34. The cam member 30 presses the brake members 23A and 23B against the stationary member 24 between the brake members 23A and 23B, restricting the movement of the brake members 23A and 23B toward each other. Therefore, the movement of the pair of brake members 23A and 23B away from the stationary member 24 is restricted. Furthermore, frictional force acts on braking member 23A in the direction opposite to the rotational direction of output member 22, causing it to rotate around support shaft 34 in a direction away from the other braking member 23B. This rotation increases the frictional force on the contact surface between stationary member 24 and braking member 23A, causing a self-amplifying increase in braking torque. Therefore, braking members 23A and 23B come to a standstill, restricting the rotation of cam member 30 and output member 22.

[0038] It is desirable to increase the distance between the contact portions of the cam member 30 and the pair of braking members 23A, 23B. Increasing the distance reduces the angle of rotation of the cam member 30 (specifically, the protrusion 30b of the cam member 30) sandwiched between the braking members 23A, 23B within the gap S1, thereby reducing backlash of the output member 22. Furthermore, the load acting on the cam member 30 is reduced, thereby increasing the strength of the clutch. It is also desirable to position the support shaft 31 connecting the cam member 30 and the output member 22 radially outward. Positioning the support shaft 31 radially outward reduces the rotation angle of the output member 22 at the position where the rotation of the cam member 30 is restricted, thereby reducing backlash of the output member 22. Furthermore, the load acting on the support shaft 31 is reduced, thereby increasing the strength of the clutch. In addition, in the prior art, the engagement portion of the output member and the contact portion of the pair of engaging members are symmetrical, and the length of r is limited because it significantly affects the strength and backlash of the output member. However, in the clutch according to the present invention, the distance between the contact portions X1, X2 between the cam member 30 and the pair of braking members 23A, 23B can be increased even if r is reduced, so there is a high degree of freedom in designing r. Therefore, there is no need to increase R to satisfy the relationship in Equation 2, and the outer diameter size can be reduced.

[0039] As described above, in the reverse input cutoff clutch of the comparative example, when torque is input to the input member 21, the pair of braking members 23A, 23B separate from the stationary member 24. In this separated state, the torque input to the input member 21 is transmitted to the output member 22, causing the output member 22 to rotate. Furthermore, when torque is input to the output member 22, the cam member 30 rotates, causing the first and second braking members 23A, 23B to move relatively apart. This presses the first and second braking members 23A, 23B against the stationary member 24, blocking the transmission of torque from the output member 22 to the input member 21. The first and second braking members 23A, 23B move relatively apart due to the rotation of the cam member 30 interposed between the first braking member 23A and the second braking member 23B. At this time, the cam member 30 restricts the first and second braking members 23A, 23B from approaching each other, effectively preventing the pair of braking members 23A, 23B from moving away from the stationary member 24. Furthermore, when the first and second braking members 23A, 23B move away from each other, the end of the cam member 30 on the first braking member side comes into contact with the first braking member 23A, and the end on the second braking member side comes into contact with the second braking member 23B, and if the end on the first braking member side rotates counterclockwise, the end on the second braking member side also rotates counterclockwise. In this case, the end on the first braking member side presses the first braking member toward the side opposite the second braking member, and the end on the second braking member side presses the second braking member toward the side opposite the first braking member. Incidentally, by setting a relatively long distance between the first contact portion X1 on the cam member side that contacts the first braking member 23A and the second contact portion X2 on the cam member side that contacts the second braking member 23B, the angle of rotation of the cam member 30 between the first and second braking members 23A and 23B is reduced, thereby reducing backlash of the output member 22. Moreover, the load acting on the cam member 30 can be reduced, thereby increasing the strength of the clutch.

[0040] Therefore, in the present invention, it is possible to reduce the backlash of the output member 22. Moreover, it is possible to reduce the load acting on the cam member 30, thereby increasing the strength of the clutch.

[0041] Next, the reverse input cutoff clutch according to the present invention will be described with reference to FIGS. 1 to 9. In this case, differences in configuration from the comparative example will be described. In the reverse input cutoff clutch shown in FIG. 11 etc., the braking members 23A, 23B are connected by a support shaft 34, but the reverse input cutoff clutch shown in FIG. 1 does not use a support shaft 34. The protrusions 33, 33 protruding inward from one longitudinal end of the main body 32, 32 of the braking member 23 are cylindrical protrusions 33A, 33B whose opposing surfaces are cylindrical. Furthermore, the reverse input cutoff clutch according to the present invention is provided with a reduction means K for reducing the surface pressure generated at the contact portion of the bearing 40 that rotatably supports the output member 22, as will be described later.

[0042] In the comparative example, the output member 22 has one arm 22b. 1 and other figures, a pair of arms 22b1, 22b2 extend in opposite radial directions. In this case, they extend in opposite directions by 180°. In addition, a recess-projection fitting structure M3 that constitutes the reduction means K is provided between arm 22b2 and cam member 30.

[0043] In this case, a protruding shaft portion 61 that protrudes toward the cam member 30 is provided on the radially outer end of arm 22b2, and a hole portion 62 into which this protruding shaft portion 61 can fit is provided in the cam member 30. This shaft portion 61 and hole portion 62 form a concave-convex fitting structure M3. In this case, the hole portion 62 is an elongated hole that is long in the swing direction so that the cam member 30 can swing within a predetermined range around the support shaft portion 31. Note that a hole portion is provided in arm 22b2, and by fitting the protruding shaft portion 61 into this hole, the protruding shaft portion 61 is provided integrally with arm 22b2, with a portion of it protruding toward the cam member 30.

[0044] In the reverse input cutoff clutch shown in FIG. 1 etc., when torque is reversely input to the output member 22, the output member 22 rotates, similar to the reverse input cutoff clutch shown in FIG. 11 etc., and the support shaft 31, which rotatably connects the output member 22 and the cam member 30, rotates (revolves). The rotation (revolution) of the support shaft 31 causes the cam member 30 to press each of the pair of braking members 23A, 23B toward the stationary member 24. The braking member 23A, which comes into contact with the cam member 30 at X1, is stationary because the relationship of reverse input torque T<braking torque T'. The braking member 23B, which has the relationship of reverse input torque T>braking torque T', rotates around the rotation axis O, and the cylindrical protrusions 33A, 33B of the braking member 23A come into contact with each other. A force acts on the cylindrical protrusion 33A of the braking member 23A in the same rotational direction as the output member 22. The cam member 30 presses the brake members 23A, 23B against the stationary member 24, restricting the movement of the brake members 23A, 23B toward each other. Therefore, the movement of the pair of brake members 23A, 23B away from the stationary member 24 is restricted. Furthermore, frictional force acts on the brake member 23A in the direction opposite to the rotational direction of the output member 22, causing the brake member 23A to rotate away from the brake member 23B around the contact points of the cylindrical protrusions 33A, 33B as a fulcrum. This rotation increases the frictional force at the contact surfaces between the stationary member 24 and the brake member 23A, resulting in a self-amplifying increase in braking torque. Therefore, the brake members 23A, 23B are stationary, restricting the rotation of the cam member 30 and the output member 22.

[0045] FIG. 5 shows the operation when torque is input to the input member 21. When torque is input to the input member 21, the input member 21 comes into contact with each of the pair of braking members 23A, 23B, pressing the pair of braking members 23, 23 toward each other. The pair of braking members 23, 23 come into contact with each other's cylindrical protrusions 33A, 33B, and rotate around the contact points of the cylindrical protrusions 33A, 33B as a fulcrum in a direction in which the braking members 23, 23 approach each other. Due to the rotation, the braking members 23, 23 move away from the stationary member 24, and the pair of braking members 23, 23 rotate with the cam member 30 sandwiched between them. The rotation of the cam member 30 rotates the output member 22, which is connected to the cam member 30 by the support shaft portion 31. Therefore, the input member 21 and the output member 22 rotate synchronously.

[0046] In other words, the reverse input blocking clutch of the present invention differs from the comparative example in that it has a reduction means K and cylindrical protrusions 33, 33 on a pair of braking members 23A, 23B, but it exhibits the same effects as the comparative example.

[0047] The comparative example does not include the fitting structure M, which is a feature of the present invention. Without the fitting structure M, when torque is input reversely to the output member 22, the cam member 30 presses the pair of braking members 23A, 23B against the stationary member 24, causing the cam member 30 to stop. The output member 22, which is connected to the stationary cam member 30 by the support shaft portion 31, rotates around the support shaft portion 31 and comes into contact with the bearing 40 disposed between the stationary member 24 and the output member 22. Therefore, when the input member 21 rotates while torque is input reversely to the output member 22, the output member 22 and the bearing 40 rotate while rubbing against each other with high surface pressure at the contact portion, as shown in FIG. 18 . This results in large frictional loss and low transmission efficiency.

[0048] However, in the case of the device equipped with the reduction means K consisting of the concave-convex fitting structure M3, the shaft portion 61 provided on the output member 22 is fitted (inserted) into the hole portion 62 provided in the cam member 30, thereby restricting the rotation (oscillation) of the output member 22 beyond a predetermined amount. As a result, the bearing 40 and the output member 22 do not come into strong contact with each other, and the rotation of the output member 22 is restricted.

[0049] In this case, the relative rotation angle between the cam member 30 and the output member 22, which is limited by the recess-projection fitting structure M3, i.e., the rotation stop of the cam member, needs to be set as follows: These will be explained using Figs. 8 and 9.

[0050] 8, the symmetrical axis of the pair of braking members 23A, 23B is defined as a first reference line C1, and an axis perpendicular to the first reference line C1 at the center of the stationary member 24 is defined as a first perpendicular line P1. The distance between the pair of braking members 23A, 23B is defined as b, the width of cam member 30 (the width of protrusion 30b) as x, the longitudinal length of protrusion 30b as y, the angle formed by first perpendicular line P1 and diagonal line d1 of protrusion 30b of cam member 30 as α, the angle formed by end face 30b1 of cam member 30 and diagonal line d1 of protrusion 30b of cam member 30 as β, the distance from center O1 of protrusion 30b of cam member 30 to center O2 of support shaft portion 31 as L1, and the distance from center O2 of support shaft portion 31 to the center of stationary member 24 (center of rotation O of the output member) as L2. When braking members 23A and 23B are in contact with stationary member 24, b is greater than x. When torque is input in reverse to output member 22, output member 22 rotates, causing support shaft 31, which rotatably connects output member 22 and cam member 30, to rotate. The rotation of support shaft 31 brings each of the pair of braking members 23A and 23B into contact with cam member 30. At this time, the angle formed by first reference line C1 and central axis C2 of cam member 30 is θ1, the angle formed by axis C3, which connects the center of stationary member 24 (rotation center O of the output shaft) and center O2 of support shaft 31, and first reference line C1 is θ2, and the angle formed by axis C3 and central axis C2 of cam member 30 is θ3. Each relationship can be expressed by equation 3.

number

[0051] Furthermore, as can be seen from FIG. 8, α+β+θ1=90°, and therefore, by substituting α=90°-β-θ1 into the formula (3), the formula (4) can be obtained.

number

[0052] Number 4 can be converted into the following formula, Number 5.

number

[0053] In addition, β can be expressed by the following equation 6, and by substituting this into equation 5, we obtain the following equation 7. This allows θ1 to be expressed as the following equation 8.

number

number

number

[0054] Furthermore, θ2 can be expressed by the following equation 9, and L3 can be expressed by the following equation 10. Therefore, by substituting L3 into the equation 9, it can be expressed by the following equation 11.

number

number

number

[0055] Furthermore, θ3 can be expressed by the following equation 12, and by substituting the equations 11 and 8 into this, the following equation 13 can be obtained.

number

number

[0056] As shown in FIG. 9, the outer diameter of output shaft portion 22a is d, and the inner diameter of bearing 40 supporting output shaft portion 22a is D. Contact between each of the pair of braking members 23A, 23B and cam member 30 restricts the movement of cam member 30 and support shaft portion 31. Due to the torque reversely input to output member 22, output shaft portion 22b rotates around center O2 of support shaft portion 31. When output shaft portion 22b is in contact with output shaft support bearing 40, L4 is the distance from the center of stationary member 24 to center O of output shaft portion 22b, and θ4 is the angle formed by axis C4 connecting center O of stationary member 24 and center O2 of support member 1 with axis C5 connecting center O3 of output shaft portion 22a and center O2 of support shaft portion 31. L4 can be expressed by equation 14.

number

[0057] Moreover, θ4 can be expressed by Equation 15, and by substituting Equation 14 into Equation 15, the following Equation 16 is obtained.

number

number

[0058] By using the detents provided on the output member 22 and the cam member 30 to limit the relative rotation angle between the output member 22 and the cam member 30 to less than θ4 as shown in Equation 16, strong contact between the output member 22 and the bearing 40 can be prevented. Furthermore, if the relative rotation angle is limited to less than θ3 as shown in Equation 13, the cam member 30 and the brake member 23A do not come into contact at the contact point X1 between the cam member 30 and the brake member 23A near the center of the stationary member 24, but the cam member 30 and the brake member 23B come into contact only at the contact point X2 between the cam member 30 and the brake member 23B away from the center O of the stationary member 24. In this case, the reverse input torque T transmitted from the cam member 30 to the brake member 23B becomes larger than the braking torque T', and the reverse input is not blocked. To block the reverse input, the relative rotation angle limited by the detent must be greater than θ3. Therefore, the relative rotation angle between the cam member 30 and the output member 22 limited by the detent must be greater than θ3 and less than θ4.

[0059] In this way, by setting θ to be equal to or greater than θ3, which can be calculated using Equation 13, and less than θ4, which can be calculated using Equation 16, it is possible to configure a reduction means K that reduces the surface pressure generated at the contact portion of the bearing 40 that pivotally supports the output member 22. Therefore, by providing such a reduction means K, it is possible to prevent losses due to wear at the contact portion and prevent a decrease in transmission efficiency. In particular, by limiting θ to less than θ4, it is possible to prevent strong contact between the output member 22 and the bearing 40, and by setting θ to be equal to or greater than θ3, it is possible to effectively exhibit the anti-rotation function that blocks reverse input.

[0060] 1, the reverse input cutoff clutch is interposed between a pair of braking members 23, 23, and the first contact portion X1 that contacts one braking member 23A and the second contact portion X2 that contacts the other braking member 23B are configured by a single protrusion 30b. That is, the edge X1 on the support shaft side of the side of protrusion 30b facing the first braking member is the first contact portion, and the edge X2 on the anti-support shaft side of the side of protrusion 30b facing the second braking member is the second contact portion. However, as shown in FIG. 10, two protrusions 30c, 30d may be used. That is, the protrusion closer to support shaft 31 is the first protrusion 30c, and the protrusion farther from support shaft 31 is the second protrusion 30d, with the edge of protrusion 30c facing the first braking member being the first contact portion X1 and the edge of protrusion 30d facing the first braking member being the second contact portion X2.

[0061] 1, and the reverse input cutoff clutch shown in FIG. 10 has the same components as those shown in FIG. 1, etc., with the same reference numerals used to designate the same components. Therefore, the reverse input cutoff clutch shown in FIG. 10 has the same effects as the reverse input cutoff clutch shown in FIG. 1. Moreover, the one shown in FIG. 10 has the advantage that a space can be provided between the first protrusion 30c and the second protrusion 30d, making the volume smaller than that of the protrusion 30b shown in FIG. 1, and reducing the weight of the cam member 30.

[0062] Incidentally, an elastic member 50 may be provided on the braking members 23A, 23B, as shown by the imaginary lines in Fig. 3. In this case, the elastic member 50 biases the braking members 23A, 23B in directions that move them relatively apart along the radial direction, and in a free state, the contact surfaces 42, 42 of the braking members 23A, 23B come into contact with a contacted surface 43a of the inner diameter surface 43 of the peripheral wall portion 35b of the stationary member 24.

[0063] Specifically, the elastic member 50 is made of a coil spring, and recessed portions 51, 51 are provided on the corresponding surfaces 23A1, 23B1 of the braking members 23A, 23B that face each other, and the ends of the elastic member 50 are fitted into the recessed portions 51, 51. As a result, the elastic member 50 is elastically biased in a direction that moves it away from the braking members 23A, 23B.

[0064] With this configuration, it is possible to synchronize the attitudes of the braking members 23, 23 and stabilize the attitude of each braking member 23, thereby enabling accurate radial movement of each braking member 23. Furthermore, as will be described later, except when rotational torque is input to the input member 21, it is possible to keep the contact surface 42 of each braking member 23 pressed against the contacted surface 43a.

[0065] While the present invention has been described above with reference to an embodiment, various modifications are possible without being limited to the above embodiment. For example, in the reverse input cutoff clutch shown in FIG. 1 and elsewhere, the pair of braking members 23A, 23B are not rotatable about the support shaft 34 as in the comparative example, but may be rotatable about the support shaft 34. Furthermore, in the illustrated example, the concave-convex fitting structure M3 has the shaft 61 provided on the output member 22 side and the hole 62 provided on the cam member 30 side. However, the shaft 61 may be provided on the cam member 30 side and the hole 62 may be provided on the output member 22 side. Furthermore, the hole 62 may be a through hole or a blind hole. The elastic member may be a spring (such as a coil spring, leaf spring, or disc spring) made of metal or other material, a rubber material, or a resin material. Furthermore, this reverse input cutoff clutch is symmetrical when viewed from both the input side and the output side, and when torque is input to the input member 21, the action is the same whether it is clockwise or counterclockwise, and when torque is input in reverse to the output member 22, the action is the same whether it is clockwise or counterclockwise. [Explanation of symbols]

[0066] 21 Input member 21a Input shaft 22 Output member 22a Output shaft 22b Arm part 23, 23A, 23B Braking material 23a Braking member pressed surface 24 Stationary Members 30 Cam member 30a KARA main body part 30b protrusion (convex part) 30c convex part 30d convex part 31 Support shaft (connecting part) 33, 33A, 33B Protrusions 34 Support shaft 61 Protruding shaft 62 acupoints M1 Distancing Movement Mechanism M2 Chuanda Agency M3 Concave-convex interlocking structure K Reduction Methods O Rotation axis Contact parts (ends) of X, X1, and X2

Claims

1. A reverse input cutoff clutch having an input member to which torque is input, an output member to which torque is output, a first braking member and a second braking member capable of reciprocating in a radial direction, and a stationary member disposed radially outside the first braking member and the second braking member, and equipped with a bearing that rotatably supports the output member, a separating movement mechanism that, when torque is input to the input member, moves the first braking member and the second braking member in a direction in which they approach each other in the radial direction, and moves the first braking member and the second braking member in a direction in which they move away from the stationary member; a transmission mechanism that transmits torque input to the input member to the output member in a state in which the first braking member and the second braking member are spaced apart from the stationary member; a cam member is interposed between the first braking member and the second braking member, and when torque is input in reverse to the output member, the rotational motion is transmitted to the cam member, causing the first braking member and the second braking member to move in a direction away from each other in the radial direction, and the first braking member and the second braking member are pressed against the stationary member, thereby blocking the transmission of torque from the output member to the input member; the output member has an output shaft portion disposed coaxially with the axis of the input shaft portion of the input member, and a pair of arm portions extending in opposite radial directions from the output shaft portion, the cam member being connected to a radially outer diameter side end of one of the arm portions of the output member via a support shaft portion; A reverse input cut-off clutch characterized in that a concave-convex fitting structure is provided between the radially outer diameter end of the other arm portion of the output member and the side of the cam member opposite the support shaft portion, and when the concave-convex fitting structure is fitted, the amount of swing of the output member around the support shaft portion is limited.

2. 2. The reverse input cutoff clutch according to claim 1, wherein the concave-convex fitting structure is composed of a protruding shaft portion and a hole portion into which the protruding shaft portion fits, and the hole portion is an elongated hole that is long in the direction in which the protruding shaft portion rotates around the support shaft portion.

3. The cam member has a cam main body portion that extends radially and has one radial end connected to a radially outer diameter side end of one of the arm portions of the output member, and a protrusion portion that is provided on the cam main body portion and disposed between the first braking member and the second braking member, and when torque is reverse input to the output member, the cam main body portion swings at the connecting portion of one of the arms around the output shaft portion of the output member, and the first contact portion and the second contact portion of the protrusion press against the brake member pressed surfaces of the first braking member and the second braking member, respectively, and move in directions that move radially away from each other.

4. 4. The reverse input cutoff clutch according to claim 3, wherein an intermediate portion between the first contact portion and the second contact portion is disposed at a position radially spaced apart from the rotation center of the input shaft portion of the input member, and the first contact portion and the second contact portion of the cam member have a different distance to the rotation center of the input shaft portion of the input member.

5. 4. The reverse input cut-off clutch according to claim 3, wherein the first braking member and the second braking member swing about one radial end side, and the swing center is disposed on the opposite side of the intermediate portion of the first contact portion and the second contact portion with respect to a perpendicular line that passes through the rotation center of the input shaft and is perpendicular to the pressed surface of the braking member.

6. 3. The reverse input cut-off clutch according to claim 1, wherein opposing protrusions are provided on one radial end of the first braking member and one radial end of the second braking member, the opposing surfaces of the protrusions are cylindrical, and when torque is input to the input member, the protrusions come into contact with each other, and the first braking member and the second braking member swing toward each other with the protrusion contact point as a fulcrum, causing the first braking member and the second braking member to move away from the stationary member.

7. 3. The reverse input cutoff clutch according to claim 1, wherein the first braking member and the second braking member are rotatable about a support shaft portion.

8. 3. The reverse input cutoff clutch according to claim 2, wherein the protrusion of the cam member is configured as a pair of convex portions spaced apart in the radial direction.

9. 3. The reverse input disconnect clutch according to claim 1, wherein the input member and the output member are rotatably supported relative to the stationary member.

Images