Actuator

Abstract

To suppress falling of a rolling element with an easily processable structure.SOLUTION: An actuator has: a first cam; a second cam facing the first cam; and a rolling element rotationally provided between the first cam and the second cam. The first cam has a plurality of grooves. The rolling element is arranged inside the plurality of grooves. The actuator has a guide groove extending in a circumferential direction from end parts in a circumferential direction of the plurality of grooves, and has a connection part between the plurality of grooves and the guide groove. The connection part has a stepped part in a front view or a stepped part in a cross-sectional view.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an actuator.

Background Art

[0002] Patent Document 1 discloses a technique for restricting the relative rotation of a second cam member and a first cam member to an angle at which a cam follower jumps out of a cam groove by providing stopper means including a fitting protrusion formed on the radially outer periphery of a second cam groove and a fitting concave groove formed on the radially outer periphery of a first cam groove.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Providing protrusions on a cam as in the above technique complicates the machining.

[0005] The present invention has been made in view of such problems, and an object thereof is to suppress the dropout of rolling elements with a structure that is easy to machine.

Means for Solving the Problems

[0006] An actuator according to an aspect of the present invention includes a first cam, a second cam facing the first cam, and a rolling element provided between the first cam and the second cam so as to be rollable. The first cam has a plurality of groove portions, and the rolling element is disposed inside the plurality of groove portions. The actuator has guide groove portions extending in the circumferential direction from the circumferential ends of the plurality of groove portions, and has connection portions between the plurality of groove portions and the guide groove portions. The connection portions have step portions when viewed from the front or in cross section.

Effects of the Invention

[0007] According to this aspect, a rolling element that tries to protrude in the circumferential direction from the groove portion can be retained on the track of the guide groove portion via the step portion. Further, since the guide groove portion is constituted by a groove, it is easy to machine. Therefore, it is possible to suppress the dropout of the rolling element with a structure that is easy to machine.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0010] FIG. 1 is a schematic configuration diagram of an actuator 1 according to this embodiment. The actuator 1 is an electric motor and is provided in, for example, a vehicle. The actuator 1 has a ball cam mechanism 10 that operates by the power of the actuator 1. The ball cam mechanism 10 is provided in a cylindrical housing 2 of the actuator 1 and is integrally assembled to the actuator 1.

[0011] The ball cam mechanism 10 has a first cam 11, a second cam 12, and a ball 13. The first cam 11 is a driving cam and rotates by the power of the actuator 1. The first cam 11 has an inner end portion 111 on the inner peripheral side, an intermediate portion 112, and an outer end portion 113 on the outer peripheral side.

[0012] The inner end portion 111 extends radially outward from the inner peripheral surface of the first cam 11 to form a cylindrical portion with a cross-sectional block shape. The inner circumference of the inner end portion 111 is slidably provided on the shaft member 3 of the actuator 1, and the first cam 11 rotates around the shaft member 3.

[0013] The axis of the shaft member 3 is aligned with the axis of the actuator 1 (the axis of the motor portion of the actuator 1). The extending direction of the shaft member 3 corresponds to the axial direction of the actuator 1, the radial direction of the shaft member 3 corresponds to the radial direction of the actuator 1, and the circumferential direction of the shaft member 3 corresponds to the circumferential direction of the actuator 1, respectively.

[0014] The intermediate portion 112 connects the inner end portion 111 and the outer end portion 113. The intermediate portion 112 has a bottomed cylindrical shape and includes a cylindrical portion 112a, a bottom wall portion 112b, and a connecting portion 112c.

[0015] The cylindrical portion 112a is provided on the radially outer side of the intermediate portion 112 and extends along the axial direction. At the end portion (the left end portion in FIG. 1) of the cylindrical portion 112a on the side opposite to the opening 2a side of the housing 2, the bottom wall portion 112b is connected. The bottom wall portion 112b is provided on the opening 2a side (the right side in FIG. 1) of the housing 2 rather than the inner end portion 111.

[0016] The connecting portion 112c is provided on the radially inner side of the bottom wall portion 112b and is connected to the inner end portion 111. The connecting portion 112c is formed by a tapered cylindrical portion and extends radially inward in the direction from the bottom wall portion 112b along the axial direction toward the inner end portion 111 (the left side in FIG. 1) and is continuous with the outer peripheral side of the inner end portion 111. For this reason, the inner end portion 111 constitutes a portion recessed from the bottom wall surface of the bottom wall portion 112b.

[0017] The outer end portion 113 extends radially outward from the outer periphery (the left outer periphery in FIG. 1) on the bottom wall portion 112b side of the cylindrical portion 112a, and then extends along the axial direction toward the inner end portion 111 side (the left side in FIG. 1). A lip seal 4 is provided between the outer periphery of the cylindrical portion 112a where the outer end portion 113 is not provided and the inner periphery of the housing 2. The lip seal 4 prevents hydraulic oil, foreign matter, etc. from entering the housing 2 from the outside of the housing 2.

[0018] The second cam 12 is provided opposite to the first cam 11. The second cam 12 is a driven cam and moves axially in accordance with the rotation of the first cam 11. The second cam 12 has a cylindrical portion 121, a connecting portion 122, and a bottom wall portion 123.

[0019] The cylindrical portion 121 has a cross-sectional block shape and extends along the axial direction. The end portion on the inner end portion 111 side (the left end portion in FIG. 1) of the cylindrical portion 121 is provided inside the connecting portion 112c and faces the inner end portion 111 along the axial direction. The inner periphery of the cylindrical portion 121 is slidably provided on the outer periphery of the shaft member 3.

[0020] The end portion on the opening 2a side (the right end portion in FIG. 1) of the cylindrical portion 121 is connected to the cylindrical connecting portion 122. The connecting portion 122 connects the cylindrical portion 121 and the bottom wall portion 123. The bottom wall portion 123 is connected to the connecting portion 122 from the opening 2a side (the right side in FIG. 1), and a through hole that opens around the axis is provided in the bottom wall portion 123. A shaft member 30 is slidably inserted into the through hole.

[0021] The shaft member 30 is a power transmission shaft, and a clutch hub 61 described later is fixed to the shaft member 30. The shaft member 30 is slidably inserted into the hollow shaft member 3 of the actuator 1 through the through hole in the bottom wall portion 123.

[0022] The first cam 11 has a first groove portion 11a, and the second cam 12 has a second groove portion 12a. In FIG. 1, the first groove portion 11a and the second groove portion 12a are shown schematically. The first groove portion 11a and the second groove portion 12a are cam grooves and face each other along the axial direction.

[0023] The first groove portion 11a is provided on the first cam surface 11b, and the second groove portion 12a is provided on the second cam surface 12b. The first groove portion 11a and the first cam surface 11b are provided at the inner end portion 111 of the first cam 11, and the second groove portion 12a and the second cam surface 12b are provided on the cylindrical portion 121 of the second cam 12. The first cam surface 11b and the second cam surface 12b face each other along the axial direction.

[0024] In the usage state of the actuator 1, the first cam surface 11b and the second cam surface 12b are arranged along the vertical direction (the up-and-down direction in FIG. 1). That is, the actuator 1 is arranged horizontally so to speak. The orientations of the first cam surface 11b and the second cam surface 12b in the usage state may change according to the posture of the vehicle on which the actuator 1 is mounted and the like.

[0025] The ball 13 is a rolling element and is provided between the first cam 11 and the second cam 12 so as to be rollable. The ball 13 is arranged inside the first groove portion 11a. The ball 13 is further arranged inside the second groove portion 12a. By providing the second groove portion 12a in addition to the first groove portion 11a, the ball 13 can be held more stably. The ball 13 mediates the transmission of the power of the actuator 1 from the first cam 11 to the second cam 12.

[0026] The actuator 1 further has a clutch 50. In the actuator 1, by further providing the clutch 50, a ball cam clutch mechanism is configured. Note that the actuator 1 can also be understood as having a configuration without the clutch 50.

[0027] The clutch 50 has a plurality of drive plates 51 and a plurality of driven plates 52, and disconnects and connects the clutch hub 61 and the clutch drum 62. The clutch hub 61 and the clutch drum 62 are two connecting members connected to each other via the clutch 50 and are composed of, for example, rotating bodies. One of the two connecting members may be a fixed member.

[0028] The clutch hub 61 has a cylindrical portion 61a on the outer peripheral side, and a plurality of drive plates 51 are attached to the outer periphery of the cylindrical portion 61a so as to be axially slidable by spline connection. The clutch drum 62 has a cylindrical portion 62a on the radially outer side of the cylindrical portion 61a, and a plurality of driven plates 52 are attached to the inner periphery of the cylindrical portion 62a so as to be axially slidable by spline connection.

[0029] The clutch 50 is connected and disconnected by a piston 63 via a return spring 64. The piston 63 is a stepped cylinder and is slidably provided on the shaft member 30. The return spring 64 is composed of a plurality of disc springs and is installed at the reduced-diameter portion 63a on the tip side (left side in FIG. 1) of the piston 63. The return spring 64 may be composed of a single disc spring.

[0030] A needle bearing 65 for receiving an axial load is provided between the piston 63 along the axial direction and the second cam 12, and the power of the actuator 1 is transmitted from the second cam 12 to the piston 63 via the needle bearing 65.

[0031] When the clutch 50 is engaged, the second cam 12 moves toward the clutch 50 side (right side in FIG. 1) in response to the rotation of the first cam 11 in the engagement direction of the clutch 50, and pushes the piston 63 toward the clutch 50 side via the needle bearing 65. As a result, the piston 63 moves toward the clutch 50 side while compressing the return spring 64, and the clutch 50 is brought into an engaged state by the pressing force transmitted from the piston 63. A retainer plate 66 is provided adjacent to the clutch 50 from the side opposite to the piston 63 (right side in FIG. 1), and the retainer plate 66 prevents the plurality of drive plates 51 and the plurality of driven plates 52 from falling over.

[0032] When the clutch 50 is released, the second cam 12 moves to the side opposite to the clutch 50 (the left side in FIG. 1) in response to the rotation of the first cam 11 in the release direction of the clutch 50. As a result, the piston 63 moves toward the side opposite to the clutch 50 while being pushed by the return spring 64, and when the pressing force is no longer transmitted from the piston 63 to the clutch 50, the clutch 50 is in the released state.

[0033] Next, the operation of the ball cam mechanism 10 will be described.

[0034] FIG. 2 is an explanatory diagram of the operation of the ball cam mechanism 10. In FIG. 2, the first groove portion 11a and the second groove portion 12a along the circumferential direction are developed and schematically shown. The forward rotation direction R1 is the rotation direction of the first cam 11 that advances the second cam 12 along the axial direction, and corresponds to the fastening direction of the clutch 50. The reverse rotation direction R2 is the rotation direction of the first cam 11 that retracts the second cam 12 along the axial direction, and corresponds to the release direction of the clutch 50.

[0035] In the state A1, the ball 13 is held at a position corresponding to the lowest point P of the first groove portion 11a and the second groove portion 12a. The lowest point P is the position where the groove is the deepest, and both the first groove portion 11a and the second groove portion 12a are formed such that the groove becomes shallower as it moves away from the lowest point P on both sides in the circumferential direction. The lowest point P1 indicates the lowest point P of the first groove portion 11a, and the lowest point P2 indicates the lowest point P of the second groove portion 12a.

[0036] When the actuator 1 rotates the first cam 11 in the forward rotation direction R1 from the state A1, the ball cam mechanism 10 transitions from the state A1 to the state A2. At this time, the ball 13 is pushed out toward the second cam 12 by the first cam 11, and as a result, the second cam 12 moves along the axial direction away from the first cam 11. As a result, the piston 63 (see FIG. 1) moves toward the clutch 50 side to fasten the clutch 50.

[0037] When the actuator 1 rotates the first cam 11 in the reverse direction R2 from the state A2, the ball cam mechanism 10 returns to the state A1. As a result, the piston 63 (see FIG. 1) moves in a direction away from the clutch 50, and the clutch 50 is released.

[0038] The rotational position of the first cam 11 is detected by a hall sensor of the actuator 1 which is an electric motor, and the first cam 11 is driven based on the detected rotational position of the first cam 11. On the other hand, since the position of the ball 13 is indirectly grasped by the rotational position of the first cam 11, the relative position can be sensed, but the absolute position cannot be sensed.

[0039] For this reason, when the first cam 11 is rotated in the forward rotation direction R1 until the second cam 12 is pushed through, there is a concern that the ball 13 may jump out of the first groove portion 11a as shown in the state A3. Further, when the first cam 11 is rotated in the reverse direction R2, combined with the spring force of the return spring 64 (see FIG. 1), as a result, the first cam 11 is suddenly returned to the state A1, and there is a concern that the ball 13 may jump out of the first groove portion 11a as shown in the state A4.

[0040] In the ball cam mechanism 10, zero point correction can be performed each time with the lowest point P as the zero point (origin). When performing zero point correction, zero point search using the engagement of the ball 13 at the lowest point P is performed. In the zero point search, for example, the first cam 11 is rotated while applying a weak torque in the reverse direction R2 from the state A2, and the point where the first cam 11 stops moving is set as a new zero point.

[0041] However, the protrusion of the ball 13 as described above also poses a concern during zero point search (for example, during zero point search in the reverse direction R2). Further, although the rotation angle of the first cam 11 is set to an angle corresponding to the length of the first groove portion 11a, when searching for an engagement starting from a state where the ball 13 is far from the lowest point P during zero point search, the rotation of the first cam 11 gains momentum and the first cam 11 may rotate excessively. As a result, the ball 13 may jump out of the first groove portion 11a.

[0042] In the usage state of the actuator 1, the first cam surface 11b and the second cam surface 12b (see FIG. 1) are arranged along the vertical direction. In this case, it becomes difficult to control the ball 13 that has jumped out of the first groove portion 11a to return to the first groove portion 11a by utilizing gravity.

[0043] The first cam surface 11b and the second cam surface 12b may be inclined within a range forming an acute angle downward with respect to the vertical direction in the usage state of the actuator 1, that is, inclined closer to the vertical direction with respect to the horizontal direction and the vertical direction. Also in this case, it becomes difficult to control the ball 13.

[0044] In view of the above circumstances, the actuator 1 is configured as described below.

[0045] FIG. 3 is an explanatory view of the first guide groove portion 11c. In FIG. 3, together with the front view of the first cam 11, the developed cross sections of the first groove portion 11a and the second groove portion 12a corresponding to the cross-sectional view, and the groove cross section of the first guide groove portion 11c are shown. The cross-sectional view is a cross-sectional view of a cross section along the circumferential direction, and the developed cross section corresponds to the cross-sectional view.

[0046] As shown in FIG. 3, a plurality (here, three) of the first groove portions 11a are provided along the circumferential direction, and the ball 13 is provided for each of the plurality of first groove portions 11a. Accordingly, the actuator 1 has a plurality of first groove portions 11a and a plurality of balls 13. Further, the actuator 1 has the same number of second groove portions 12a as the plurality of first groove portions 11a.

[0047] As shown in the developed cross-section, the first groove portion 11a has a first bottom portion 11aa and a second bottom portion 11ab. The first bottom portion 11aa is the bottom portion where the ball 13 held at the position corresponding to the lowest point P moves while contacting during the forward rotation of the first cam 11, and is located behind the lowest point P1 in the forward rotation direction R1. The second bottom portion 11ab is provided on the side opposite to the first bottom portion 11aa with the lowest point P1 interposed therebetween in the circumferential direction, and is located in front of the lowest point P1 in the forward rotation direction R1. The first bottom portion 11aa and the second bottom portion 11ab are connected to each other at the lowest point P1.

[0048] In the first groove portion 11a, the lowest point P1 is set at a position closer to the front in the forward rotation direction R1. Therefore, in the first groove portion 11a, the groove length of the first bottom portion 11aa along the circumferential direction is longer than that of the second bottom portion 11ab.

[0049] Both the first bottom portion 11aa and the second bottom portion 11ab are inclined. Both the first bottom portion 11aa and the second bottom portion 11ab are inclined with respect to the circumferential direction in a cross-sectional view. The first bottom portion 11aa and the second bottom portion 11ab approach a state parallel to the first cam surface 11b as the inclination with respect to the circumferential direction becomes gentler, that is, as the inclination angle becomes smaller.

[0050] The first bottom portion 11aa has a gentle inclination in order to move the second cam 12 in the axial direction with high precision during the forward rotation of the first cam 11. On the other hand, the second bottom portion 11ab has a steeper inclination than the first bottom portion 11aa, that is, a larger inclination angle. Thereby, during the reverse rotation of the first cam 11, the movement of the ball 13 is easily restricted by the second bottom portion 11ab.

[0051] The second groove portion 12a has a first bottom portion 12aa and a second bottom portion 12ab. The first bottom portion 12aa is a bottom portion where the ball 13 held at a position corresponding to the lowest point P moves while contacting during the forward rotation of the first cam 11, and is located forward in the forward rotation direction R1 from the lowest point P2. The second bottom portion 12ab is provided on the side opposite to the first bottom portion 12aa with the lowest point P2 interposed therebetween in the circumferential direction, and is located rearward in the forward rotation direction R1 from the lowest point P2. The first bottom portion 12aa and the second bottom portion 12ab are connected to each other at the lowest point P2.

[0052] Both the first bottom portion 12aa and the second bottom portion 12ab are inclined. Both the first bottom portion 12aa and the second bottom portion 12ab are inclined with respect to the circumferential direction in a cross-sectional view. The inclination angle of the first bottom portion 12aa is set to be equal to the inclination angle of the first bottom portion 11aa in the first groove portion 11a.

[0053] The lowest point P2 of the second groove portion 12a is set at the circumferential center of the second groove portion 12a. Therefore, in the second groove portion 12a, the first bottom portion 12aa and the second bottom portion 12ab are set so that their inclination angles are the same. By having an angle such that equal forces with the same inclination angle are applied on both sides in the circumferential direction of the lowest point P, the ball 13 held at the position corresponding to the lowest point P can be held more stably.

[0054] The first cam 11 further has a first guide groove portion 11c. A plurality of adjacent first groove portions 11a are connected via the first guide groove portion 11c. Each of the first groove portions 11a adjacent to each other in the circumferential direction is connected via an individual first guide groove portion 11c, and a plurality of first guide groove portions 11c are provided on the first cam 11. The first guide groove portion 11c extends along the circumferential direction and is disposed at a radial position corresponding to the radial center of the first groove portion 11a. The first guide groove portion 11c passes through the center line extending in the circumferential direction of the first groove portion 11a.

[0055] The first guide groove portion 11c is connected to the circumferential end E of the first groove portion 11a. In other words, the actuator 1 has the first guide groove portion 11c at the circumferential end E (the direction along the circumferential direction of the first cam 11). The end E1 indicates the front end E in the forward rotation direction R1, and the end E2 indicates the rear end E in the forward rotation direction R1. The first guide groove portion 11c extends circumferentially from the end E and connects the end E1 of one of the first groove portions 11a adjacent in the circumferential direction to the end E2 of the other. The end E has an edge whose width gradually narrows in the direction toward the outside in the circumferential direction of the first groove portion 11a when viewed from the front.

[0056] The first guide groove portion 11c extends inside the first groove portion 11a rather than the edge of the end E when viewed from the front. When viewed from the front, the edge of the first guide groove portion 11c in the portion provided in the first groove portion 11a also serves as the connection portion C between the first groove portion 11a and the first guide groove portion 11c. In other words, the actuator 1 has a connection portion C between the plurality of first groove portions 11a and the first guide groove portion 11c.

[0057] By connecting the first guide groove portion 11c to the first groove portion 11a, a first step portion S1 (the portion indicated by the thick line), which is a step portion when viewed from the front, is formed on the first cam 11. The first step portion S1 is formed in the range from the edge of the first guide groove portion 11c located outside the first groove portion 11a when viewed from the front to the edge of the end E via the first connection portion C1 of the connection portion C (the connection portion C that connects the edges of the first guide groove portion 11c and the end E when viewed from the front).

[0058] Therefore, in other words, the first connection portion C1 has the first step portion S1, which is a step portion when viewed from the front, and the first connection portion C1 is constituted by the end of the connection portion C when viewed from the front. For each of the two ends E (the end E1 and the end E2) of the first groove portion 11a, the first step portion S1 is formed on each of the radially inner side and the radially outer side of the first guide groove portion 11c.

[0059] The width W2 of the first guide groove portion 11c is smaller than the width W1 of the first groove portion 11a. As a result, a first step portion S1, which is a step portion when viewed from the front, is formed at a first connection portion C1 that connects the edges of the first guide groove portion 11c and the end portion E when viewed from the front.

[0060] In the actuator 1 configured as described above, the ball 13 that attempts to protrude in the circumferential direction from the first groove portion 11a can be retained on the track of the first guide groove portion 11c via the first step portion S1. Further, since the first guide groove portion 11c is constituted by a groove, it is easy to machine. Therefore, it is possible to suppress the dropout of the ball 13 with a structure that is easy to machine. Dropout means complete dropout where the ball 13 deviates from the tracks (circumferential lines passing through the centers of the first groove portion 11a and the first guide groove portion 11c) of the first groove portion 11a and the first guide groove portion 11c, and does not include semi-dropout where the ball 13 is outside the first groove portion 11a but on the track of the first guide groove portion 11c. Furthermore, the first guide groove portion 11c can also guide the ball 13 that has protruded from the first groove portion 11a and return it to the first groove portion 11a.

[0061] Even when the ball 13 protrudes from the first groove portion 11a and rides onto the first guide groove portion 11c, since the rotation angle of the first cam 11 is determined, the ball 13 does not move far away from the first connection portion C1. For example, during zero point search, when the first cam 11 rotates to the limit of the rotation angle, the ball 13 stops at the end of the first groove portion 11a. Even when the first cam 11 rotates too much and the ball 13 rides onto the first guide groove portion 11c, the ball 13 is near the first connection portion C1. Therefore, in this case, during zero point search, after once stopping the first cam 11, fine adjustment of rotating the first cam 11 forward and backward can return the ball 13 that has ridden onto the first guide groove portion 11c to the first groove portion 11a.

[0062] As shown in the developed cross-section, on the front side in the forward rotation direction R1 of the first groove portion 11a, the bottom portion 11ca of the first guide groove portion 11c is connected to the second bottom portion 11ab, thereby forming a second step portion S2 (the portion indicated by the thick line), which is a step portion when viewed in cross-section.

[0063] When viewed in cross-section, the second step portion S2 is formed in a range extending from the bottom 11ca of the first guide groove portion 11c, through the second connection portion C2 of the connection portion C (the connection portion C connecting the bottom 11ca and the second bottom 11ab when viewed in cross-section), to the second bottom 11ab of the portion extending from the second connection portion C2 toward the lowest point P1.

[0064] Therefore, in other words, the second connection portion C2 has the second step portion S2 which is a step portion when viewed in cross-section, and the second connection portion C2 is constituted by the end portion of the connection portion C within the first groove portion 11a when viewed in cross-section.

[0065] The second step portion S2 is also formed on the rear side in the forward rotation direction R1 of the first groove portion 11a. On the rear side in the forward rotation direction R1, when viewed in cross-section, the second step portion S2 is formed in a range extending from the bottom 11ca, through the second connection portion C2 connecting the bottom 11ca and the first bottom 11aa, to the first bottom 11aa of the portion extending from the second connection portion C2 toward the lowest point P1. The second connection portion C2 connects the bottom 11ca of the first guide groove portion 11c and the bottom of the first groove portion 11a including the first bottom 11aa and the second bottom 11ab.

[0066] The bottom 11ca of the first guide groove portion 11c is formed at a position shallower than the lowest point P1 of the first groove portion 11a. That is, the depth D2 of the first guide groove portion 11c is shallower than the depths D1 of the plurality of first groove portions 11a, whereby the second step portion S2 which is a step portion when viewed in cross-section is formed at the bottom 11ca of the first guide groove portion 11c and the second connection portion C2 connecting the bottom of the first groove portion 11a when viewed in cross-section.

[0067] In the actuator 1 configured as described above, the ball 13 that attempts to protrude circumferentially from the first groove portion 11a can be retained on the orbit of the first guide groove portion 11c via the second stepped portion S2. Further, according to the second stepped portion S2, since the ball 13 can be placed on the orbit of the first guide groove portion 11c within the first groove portion 11a, it is possible to suppress the dropout of the ball 13 at an earlier stage compared to the first stepped portion S1, and it becomes possible to make the ball 13 more difficult to drop out.

[0068] In the actuator 1, by making the depth D2 of the first guide groove portion 11c shallower than the depth D1 of the plurality of first groove portions 11a and making the width W2 of the first guide groove portion 11c smaller than the width W1 of the first groove portion 11a, both the first stepped portion S1 and the second stepped portion S2 can be formed.

[0069] In the actuator 1, by setting the width W2 and the depth D2 of the first guide groove portion 11c so that the ball 13 abuts on the edge (arc-shaped edge along the circumferential direction) of the first guide groove portion 11c without abutting on the bottom portion 11ca of the first guide groove portion 11c (refer to the groove cross-section), the ball 13 can be guided by the first guide groove portion 11c via the second stepped portion S2 within the first groove portion 11a and placed on the orbit.

[0070] The ball 13 is likely to protrude circumferentially from the first groove portion 11a when the first cam 11 is rotated in the reverse rotation direction R2 to perform the lowest point search. Therefore, if the first guide groove portion 11c is set on the side where the ball 13 can protrude (that is, the second bottom portion 11ab side) at least when the first cam 11 is reversed with respect to the first groove portion 11a, it is effective against the dropout of the ball 13.

[0071] The first groove portions 11a adjacent to each other in the circumferential direction are connected via the first guide groove portion 11c. As a result, since the absolute position of the ball 13 cannot be sensed, even if the first cam 11 is rotated to the position where the ball 13 protrudes circumferentially from the first groove portion 11a, each ball 13 can be guided by the first guide groove portion 11c and move to the plurality of first groove portions 11a, and thus can return to the original state.

[0072] The second cam 12 may have a guide groove similar to the first guide groove 11c of the first cam 11.

[0073] Next, a modified example of the actuator 1 will be described.

[0074] FIG. 4 is a diagram showing a first modified example of the actuator 1. In this example, compared with the case shown in FIG. 3, the depth D2 of the first guide groove 11c is deeper than the depth D1 of the plurality of first grooves 11a. Note that the portion indicated by the two-dot chain line in the developed cross-section shows the first groove 11a of the portion cut off by the first guide groove 11c having the depth D2 with a virtual line with respect to the developed cross-section shown in FIG. 3.

[0075] According to this example, the first step portion S1 can be formed, and the ball 13 that tries to protrude in the circumferential direction from the first groove 11a can be retained on the track of the first guide groove 11c via the first step portion S1. Further, since the first groove 11a can be formed so as to cross the first guide groove 11c along the circumferential direction, the ball 13 can be retained on the track of the first guide groove 11c over the entire circumference.

[0076] The depth D2 of the first guide groove 11c and the depth D1 of the plurality of first grooves 11a may be the same. Even in this case, the first step portion S1 can be formed, and the ball 13 can be retained on the track of the first guide groove 11c over the entire circumference. Similar to the case shown in FIG. 3, the second cam 12 may have a guide groove similar to the first guide groove 11c.

[0077] FIG. 5 is a diagram showing a second modified example of the actuator 1. In this example, compared with the case shown in FIG. 3, the second cam 12 further has a second guide groove portion 12c. Also, the width W2 of the first guide groove portion 11c is the same as the width W1 of the first groove portion 11a, and the depth D2 of the first guide groove portion 11c is set to a depth at which the ball 13 contacts the bottom portion 11ca without contacting the edge (arc-shaped edge along the circumferential direction) of the first guide groove portion 11c when the ball 13 is located at the radial center of the first guide groove portion 11c (refer to the groove cross section). The relationship between the width of the second guide groove portion 12c and the width of the second groove portion 12a, and the depth of the second guide groove portion 12c are the same.

[0078] According to this example, the second step portion S2 can be formed, and the ball 13 that tries to protrude in the circumferential direction from the first groove portion 11a can be retained on the orbit of the first guide groove portion 11c via the second step portion S2. Also, in this case, the ball 13 can be retained on the orbit of the first guide groove portion 11c by the first guide groove portion 11c and the second guide groove portion 12c. Therefore, even if the first guide groove portion 11c and the second guide groove portion 12c are configured such that the ball 13 contacts the bottom portion 11ca and the bottom portion 12ca, it is possible to make it difficult for the ball 13 to drop off.

[0079] FIG. 6 is a diagram showing a third modified example of the actuator 1. In FIG. 6, the developed cross sections of the first groove portion 11a and the second groove portion 12a corresponding to a cross-sectional view are schematically shown, and the first guide groove portion 11c and the second guide groove portion 12c are shown by two-dot chain lines. The chain lines show the case of a comparative example.

[0080] In this example, compared with the case shown in FIG. 3, the second bottom portion 11ab of the first groove portion 11a has a first inclined portion 11abA and a second inclined portion 11abB. Also, the second bottom portion 12ab of the second groove portion 12a has a first inclined portion 12abA and a second inclined portion 12abB. The first groove portion 11a and the second groove portion 12a further have a third step portion S3 shown by a thick line. The second cam 12 has a second guide groove portion 12c similar to the first guide groove portion 11c.

[0081] The first inclined portion 11abA of the first groove portion 11a is provided on the lowest point P1 side of the second inclined portion 11abB in the axial direction, and has a steeper inclination than the first bottom portion 11aa, that is, a large inclination angle. The second inclined portion 11abB is connected to the first inclined portion 11abA from the first cam surface 11b side in the axial direction, and has a gentler inclination than the first inclined portion 11abA, that is, a small inclination angle. The second inclined portion 11abB connects the first cam surface 11b and the first inclined portion 11abA.

[0082] The third step portion S3 is formed at the connection portion between the first inclined portion 11abA and the second inclined portion 11abB. In the first groove portion 11a, the second inclined portion 11abB inclines the edge of the first guide groove portion 11c, that is, the connection portion C, when viewed from the front of the portion provided in the first groove portion 11a.

[0083] Therefore, the first guide groove portion 11c has the second inclined portion 11abB and has a third connection portion C3 which is the connection portion C of the portion connecting the second inclined portion 11abB and the first inclined portion 11abA. The third connection portion C3 has a third step portion S3 which is a step portion when viewed in cross section.

[0084] The first inclined portion 12abA of the second groove portion 12a is provided on the lowest point P2 side of the second inclined portion 12abB in the axial direction, and has a larger inclination angle than the first bottom portion 12aa. The inclination angle of the first inclined portion 12abA is set to be equal to the inclination angle of the first inclined portion 11abA of the first groove portion 11a. The second inclined portion 12abB is connected to the first inclined portion 12abA from the second cam surface 12b side in the axial direction, and has a smaller inclination angle than the first inclined portion 12abA. The second inclined portion 12abB connects the second cam surface 12b and the first inclined portion 12abA.

[0085] In the second groove portion 12a, the third step portion S3 is formed at the connection portion between the first inclined portion 12abA and the second inclined portion 12abB. In the second groove portion 12a, the second inclined portion 12abB inclines the edge of the second guide groove portion 12c, that is, the connection portion C, when viewed from the front of the portion provided in the second groove portion 12a.

[0086] Therefore, the second guide groove portion 12c has a second inclined portion 12abB and has a third connection portion C3 which is a connection portion C of a portion connecting the second inclined portion 12abB and the first inclined portion 12abA, and the third connection portion C3 has a third step portion S3 which is a step portion in a cross-sectional view.

[0087] Since the second inclined portion 11abB as the inclined portion of the first guide groove portion 11c acts on the ball 13 in a direction toward the lowest point P, it is possible to make it difficult for the ball 13 to jump out from the first groove portion 11a. Further, since it becomes difficult for the ball 13 to jump out, the ball 13 easily settles at a position corresponding to the lowest point P.

[0088] In the first groove portion 11a, by providing the second inclined portion 11abB separately from the first inclined portion 11abA, while facilitating zero point search using the fact that the ball 13 stops at the first inclined portion 11abA, the first groove portion 11a can be extended in the circumferential direction, and thereby it is also possible to make it difficult for the ball 13 to jump out from the first groove portion 11a.

[0089] The second guide groove portion 12c having the second inclined portion 12abB can also make it difficult for the ball 13 to jump out in the same manner as the first guide groove portion 11c. Note that this modification example may be applied to only one of the first groove portion 11a and the second groove portion 12a.

[0090] Next, the main operating effects of the actuator 1 will be described.

[0091] (1) The actuator 1 has a first cam 11, a second cam 12 facing the first cam 11, and a ball 13 provided so as to be rollable between the first cam 11 and the second cam 12. The first cam 11 has a plurality of first groove portions 11a, and the ball 13 is disposed inside the plurality of first groove portions 11a. The actuator 1 has a first guide groove portion 11c extending in the circumferential direction from the circumferential end E of the plurality of first groove portions 11a, and has a connection portion C between the plurality of first groove portions 11a and the first guide groove portion 11c. The connection portion C has a first step portion S1 which is a step portion when viewed from the front, or a second step portion S2 or a third step portion S3 which is a step portion when viewed in cross section.

[0092] According to such a configuration, the ball 13 that attempts to jump out in the circumferential direction from the first groove portion 11a can be retained on the track of the first guide groove portion 11c via the first step portion S1, the second step portion S2, or the third step portion S3. Further, since the first guide groove portion 11c is constituted by a groove, it is easy to machine. Therefore, it is possible to suppress the dropping of the ball 13 with a structure that is easy to machine.

[0093] Due to the presence of the first step portion S1, while providing the first guide groove portion 11c, it is possible to suppress the ball 13 from easily coming out of the first groove portion 11a as compared with, for example, a case where the first groove portion 11a and the first guide groove portion 11c are smoothly connected. The first step portion S1 also has an effect of guiding the ball 13 that attempts to come out of the first groove portion 11a to the first guide groove portion 11c.

[0094] Due to the presence of the second step portion S2 or the third step portion S3, even if the ball 13 jumps out of the first groove portion 11a and rides on the first guide groove portion 11c, the height of the ball 13 (the amount of extrusion of the second cam 12 in the axial direction) is suppressed, so that the pressing force on the peripheral components can be reduced, and the deterioration of the durability of the peripheral components can be suppressed.

[0095] (2) The depth D2 of the first guide groove portion 11c is shallower than the depth D1 of the plurality of first groove portions 11a.

[0096] According to such a configuration, by forming the second step portion S2, the ball 13 can be retained on the track of the first guide groove portion 11c via the second step portion S2. Further, according to the second step portion S2, since the ball 13 can be placed on the track of the first guide groove portion 11c within the first groove portion 11a, it is possible to suppress the dropout of the ball 13 at an earlier stage compared to the first step portion S1, and it is possible to make the ball 13 more difficult to drop out.

[0097] (3) The width W2 of the first guide groove portion 11c is smaller than the width W1 of the plurality of first groove portions 11a.

[0098] According to such a configuration, by forming the first step portion S1, even if the ball 13 pops out in a way that it overruns in the circumferential direction from the first groove portion 11a, the ball 13 can be retained on the track of the first guide groove portion 11c via the first step portion S1.

[0099] (4) The depth D2 of the first guide groove portion 11c is shallower than the depth D1 of the plurality of first groove portions 11a, and the width W2 of the first guide groove portion 11c is smaller than the width W1 of the plurality of first groove portions 11a.

[0100] According to such a configuration, since the first step portion S1 and the second step portion S2 can be formed, the dropout of the ball 13 can be suppressed at an earlier stage, and even if the ball 13 pops out in the circumferential direction from the first groove portion 11a, the ball 13 can be retained on the track of the first guide groove portion 11c.

[0101] (5) The depth D2 of the first guide groove portion 11c may be deeper than the depth D1 of the plurality of first groove portions 11a, and the width W2 of the first guide groove portion 11c may be smaller than the width of the plurality of first groove portions 11a.

[0102] According to such a configuration, the first step portion S1 can be formed, and also the first groove portion 11a can be formed so as to cross the first guide groove portion 11c along the circumferential direction. Therefore, the ball 13 can be retained on the track of the first guide groove portion 11c over the entire circumference.

[0103] (6) The depth D2 of the first guide groove portion 11c is the same as the depth D1 of the plurality of first groove portions 11a, and the width W2 of the first guide groove portion 11c may be smaller than the width W1 of the plurality of first groove portions 11a.

[0104] Even with such a configuration, the first step portion S1 can be formed, and the ball 13 can be retained over the entire circumference on the track of the first guide groove portion 11c.

[0105] (7) The first guide groove portion 11c has a second inclined portion 11abB. Alternatively, the second guide groove portion 12c has a second inclined portion 12abB.

[0106] The second inclined portion 11abB and the second inclined portion 12abB have the effect of suppressing the ball 13 from completely riding up on the first guide groove portion 11c and suppressing the ball 13 from coming out of the first groove portion 11a and the second groove portion 12a. Further, the second inclined portion 11abB and the second inclined portion 12abB have the effect of guiding the ball 13 that is about to come out of the first groove portion 11a and the second groove portion 12a to the first guide groove portion 11c. Therefore, according to such a configuration, the second inclined portion 11abB or the second inclined portion 12abB can make it difficult for the ball 13 to jump out of the first groove portion 11a or the second groove portion 12a.

[0107] (8) The plurality of adjacent first groove portions 11a are connected via the first guide groove portion 11c.

[0108] According to such a configuration, even if the first cam 11 is rotated until the ball 13 jumps out in the circumferential direction from the first groove portion 11a, each ball 13 can be guided by the first guide groove portion 11c and move to the plurality of first groove portions 11a, thereby returning to the original state.

[0109] As described above, the embodiments of the present invention have been explained. However, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. For example, the actuator 1 may be used in a power transmission device that performs power transmission other than a vehicle, a machine tool, or the like. Further, for example, the third modification example described with reference to FIG. 6 may be implemented in combination with the first modification example described with reference to FIG. 4 and the second modification example described with reference to FIG. 5. That is, a plurality of modification examples may be appropriately combined and implemented.

Explanation of Reference Numerals

[0110] 1: Actuator 11: First cam 11a: First groove portion (groove portion) 11abB: Second inclined portion (inclined portion) 11c: First guide groove portion (guide groove portion) 12: Second cam 12a: Second groove portion (groove portion) 12c: Second guide groove portion (guide groove portion) 13: Ball (rolling element) C: Connection portion C1: First connection portion (connection portion) C2: Second connection portion (connection portion) C3: Third connection portion (connection portion) D1: Depth D2: Depth S1: First step portion (step portion) S2: Second step portion (step portion) S3: Third step portion (step portion) W1: Width W2: Width

Claims

1. A first cam; a second cam opposed to the first cam; a rolling body provided to be capable of rolling between the first cam and the second cam; having The first cam has a plurality of grooves, The rolling elements are disposed inside the plurality of grooves, A guide groove portion extending in a circumferential direction from an end portion in a circumferential direction of the plurality of groove portions is provided, a connection portion between the plurality of groove portions and the guide groove portion, The connection portion has a step portion when viewed from the front or a step portion when viewed in cross section. Actuator.

2. 2. The actuator of claim 1, The depth of the guide groove portion is shallower than the depth of the plurality of groove portions. Actuator.

3. 2. The actuator of claim 1, The width of the guide groove portion is smaller than the width of the plurality of groove portions. Actuator.

4. 2. The actuator of claim 1, The depth of the guide groove portion is shallower than the depth of the plurality of groove portions, The width of the guide groove portion is smaller than the width of the plurality of groove portions. Actuator.

5. 2. The actuator of claim 1, The depth of the guide groove portion is greater than the depth of the plurality of groove portions, The width of the guide groove portion is smaller than the width of the plurality of groove portions. Actuator.

6. 2. The actuator of claim 1, The depth of the guide groove portion and the depth of the plurality of groove portions are the same, The width of the guide groove portion is smaller than the width of the plurality of groove portions. Actuator.

7. 2. The actuator of claim 1, The guide groove portion has an inclined portion. Actuator.

8. 8. An actuator according to claim 1, further comprising: Adjacent grooves are connected to each other via the guide grooves. Actuator.

Images