Acceleration / deceleration device

Abstract

An acceleration / deceleration device (100) comprises a cam member (110) having one protruding part (111), an annular outer ring member (120) having a plurality of protruding parts (121) protruding inward in a curved shape, roller members (130) that roll along the shape of the inner periphery of the outer ring member (120) as the cam member (110) and the outer ring member (120) rotate relative to each other, a support member (140) having a holding part (143) that restricts circumferential-direction movement of each of the plurality of roller members (130) and allows radial-direction movement of the roller members, a housing (150) to which the outer ring member (120) is fixed, a first shaft body (161) connected to the cam member (110), and a second shaft body (162) connected to the support member (140).

Description

Acceleration / Deceleration Device

[0001] The present invention relates to an acceleration / deceleration device that functions as a speed reducer or a speed increaser.

[0002] Conventionally, as one type of acceleration / deceleration device, there is a worm gear type acceleration / deceleration device that combines a worm and a worm wheel. This acceleration / deceleration device can achieve a large reduction ratio. However, since the input shaft and the output shaft are orthogonal, an electric motor or the like attached to the input shaft protrudes from the output shaft of the acceleration / deceleration device, resulting in a problem that the freedom of the mounting location deteriorates.

[0003] On the other hand, as described in Patent Document 1, there is also a coaxial type acceleration / deceleration device in which the input shaft and the output shaft are arranged coaxially. In this acceleration / deceleration device, since the electric motor can be arranged in parallel with the input shaft and the output shaft, the freedom of the mounting location can be improved.

[0004] Japanese Patent Laid-Open No. 1994-174017

[0005] However, since the coaxial type acceleration / deceleration device has a structure in which metal gears with a large number of teeth are meshed with each other to transmit torque, there is a problem that the noise during operation is large.

[0006] The present invention has been made in view of the above problems, and provides an acceleration / deceleration device that can achieve low noise while being a coaxial type acceleration / deceleration device.

[0007] One of the acceleration / deceleration devices of the present invention comprises: a cam member having one projection; an annular outer ring member arranged concentrically with the rotation axis of the cam member and having a plurality of projections arranged circumferentially, projecting inward in a curved shape; a number of roller members different from the number of projections, arranged between the outer ring member and the cam member and constantly in contact with the inner circumference of the outer ring member and the outer circumference of the cam member, and rolling along the shape of the inner circumference of the outer ring member as the relative rotation of the cam member and the outer ring member occurs; a support member having a holding portion that restricts the circumferential movement of each of the plurality of roller members and allows radial movement of each; a housing that houses the cam member, the roller members, and the support member, and to which the outer ring member is fixed; a first shaft connected to the cam member and extending to the outside of the housing; and a second shaft connected to the support member and extending to the outside of the housing.

[0008] According to the present invention, it is possible to provide a coaxial type acceleration / deceleration device that can suppress the noise generated during operation.

[0009] Figure 1 is a perspective view showing the acceleration / deceleration device according to Embodiment 1 in an disassembled state. Figure 2 is a cross-sectional view showing a cross-section of the acceleration / deceleration device according to Embodiment 1. Figure 3 is a plan view showing the cam member according to Embodiment 1. Figure 4 is a side view showing the cam member and roller member according to Embodiment 1. Figure 5 is a plan view showing the cam member, outer ring member, roller member, and support member according to Embodiment 1. Figure 6 is a perspective view showing the roller member according to Embodiment 1. Figure 7 is a perspective view showing the support member in a disassembled state according to Embodiment 1 from the Z+ side. Figure 8 is a perspective view showing the support member in a disassembled state according to Embodiment 1 from the Z- side. Figure 9 is a cross-sectional view showing a cross-section of the acceleration / deceleration device 100 according to Embodiment 2. Figure 10 is a plan view showing the cam member, outer ring member, roller member, and support member when the number of roller members arranged radially is different.

[0010] The following describes embodiments of the acceleration / deceleration device according to the present invention with reference to the drawings. Note that the following embodiments are examples provided to illustrate the present invention and are not intended to limit it. For example, the shapes, structures, materials, components, relative positional relationships, connection states, numerical values, formulas, the content of each step in the method, and the order of each step shown in the following embodiments are examples and may include content not described below. Furthermore, geometric expressions such as parallel and orthogonal may be used, but these expressions do not indicate mathematical rigor and include substantially acceptable errors and deviations. Similarly, expressions such as simultaneous and identical also include substantially acceptable ranges.

[0011] Furthermore, the drawings are schematic diagrams that have been appropriately emphasized, omitted, or had their proportions adjusted to illustrate the present invention, and therefore differ from the actual shapes, positional relationships, and proportions. Also, the X, Y, and Z axes shown in the drawings represent orthogonal coordinates arbitrarily set for the purpose of explaining the drawings. In other words, the Z axis is not necessarily an axis along the vertical direction, and the X and Y axes are not necessarily located in the horizontal plane.

[0012] Furthermore, in the following, multiple inventions may be comprehensively described as a single embodiment. Also, some of the content described below is described as an optional component relating to the present invention.

[0013] (Embodiment 1) Figure 1 is a perspective view showing the acceleration / deceleration device 100 according to Embodiment 1 in an exploded state. Figure 2 is a cross-sectional view showing a cross-section of the acceleration / deceleration device 100 according to Embodiment 1. The acceleration / deceleration device 100 includes a cam member 110, an outer ring member 120, a roller member 130, a support member 140, a housing 150, a first shaft 161, and a second shaft 162. The acceleration / deceleration device 100 functions as a speed reducer when the first shaft 161 is used as the input shaft and the second shaft 162 is used as the output shaft, and functions as a speed increaser when the first shaft 161 is used as the output shaft and the second shaft 162 is used as the input shaft. In this embodiment, the first shaft 161 is used as the input shaft and the second shaft 162 is used as the output shaft for the explanation. The applications of the acceleration / deceleration device 100 are not particularly limited, but examples include power assist in the steering system of a moving body such as an automobile, or steering drive that generates the force to turn the steering wheels of a moving body.

[0014] The first shaft 161 is a rod-shaped member connected to the cam member 110 and extending to the outside of the housing 150. The first shaft 161 is a axial structural member that is connected to, for example, the output shaft of an electric motor via gears or belts, or directly connected, and to which the output torque of the electric motor is input. In this embodiment, the first shaft 161 is a cylindrical member and is rotatably mounted to the housing 150 via bearings 170.

[0015] Figure 3 is a plan view showing the cam member 110 according to Embodiment 1. Figure 4 is a side view showing the cam member 110 and the roller member 130 according to Embodiment 1. The cam member 110 is a member having one projection 111. In this embodiment, the cam member 110 is provided with only one projection 111. On a plane perpendicular to the rotation axis 211 of the acceleration / deceleration device 100 (the plane shown in Figure 3), the distance from the rotation axis 211 decreases linearly from the tip of the projection 111 (the part furthest from the rotation axis 211) to the part closest to the rotation axis. The cam member 110 includes a cam contact portion 112 that contacts the roller member 130 but not the outer ring member 120, and an outer ring contact portion 113 that does not contact the roller member 130 but contacts the outer ring member 120. The cam member 110 is a member that rotates together with the first shaft body 161.

[0016] In Figure 3, the cam contact portion 112 protrudes from the outer ring contact portion 113, but depending on the structure of the roller member 130, the outer ring contact portion 113 may protrude from the cam contact portion 112, or the cam contact portion 112 and the outer ring contact portion 113 may be flush. In this embodiment, the cam member 110 is provided with a plurality of through holes 119 in the same direction as the rotation axis 211. The through holes 119 bring the center of gravity of the cam member 110 closer to the rotation axis 211, thereby improving the rotational stability of the cam member 110 around the rotation axis 211. It also reduces the weight of the cam member 110.

[0017] The material that constitutes the cam member 110 is not limited, but examples include metal (including alloys) and resin.

[0018] Figure 5 is a plan view showing the cam member 110, outer ring member 120, roller member 130, and support member 140 according to Embodiment 1.

[0019] The outer ring member 120 is an annular member arranged concentrically with the rotation axis 211 of the cam member 110 and has a plurality of protrusions 121 arranged circumferentially, projecting inward in a curved shape. The number of protrusions 121 is not limited, but in this embodiment, the protrusions 121 are evenly distributed at five locations in the circumferential direction. The shape of the inner circumference of the outer ring member 120 is such that when the cam member 110 is rotated around the rotation axis 211, the roller member 130 is always in contact with the inner circumferential surface of the cam member 110 and the outer ring member 120, and the roller member 130 rotates without slipping, or with minimal slipping, with the cam member 110 and the outer ring member 120. The outer ring member 120 is also fixed to the housing 150. The fixing method is not limited, but in this embodiment, the outer ring member 120 is fixed to the housing 150 by fastening members (not shown).

[0020] The material that constitutes the outer ring member 120 is not limited, but examples include metal (including alloys) and resin.

[0021] Figure 6 is a perspective view showing a roller member 130 according to Embodiment 1. The roller member 130 is a cylindrical or round bar-shaped member positioned between the outer ring member 120 and the cam member 110. The roller member 130 is always in contact with the inner circumference of the outer ring member 120 and the outer circumference of the cam member 110, and rolls along the shape of the inner circumference of the outer ring member 120 as the cam member 110 and the outer ring member 120 rotate relative to each other. The number of roller members 130 provided in the acceleration / deceleration device 100 is not limited, but the number of roller members 130 is different from the number of protrusions 121. In this embodiment, there are six roller members 130, one more than the number of protrusions 121.

[0022] In this embodiment, the roller member 130 includes a disc-shaped first member 131 that contacts the cam contact portion 112 of the cam member 110 but does not contact the outer ring member 120, a disc-shaped second member 132 that does not contact the cam member 110 but contacts the outer ring member 120 and has a different diameter from the first member 131, and a disc-shaped third member 133 that is held by the holding portion 143 (details to be described later) of the support member 140. The first member 131, the second member 132, and the third member 133 move together in the circumferential direction, radial direction, and direction of the rotation axis 211, and the first member 131 and the second member 132 are rotatable (spinning) relative to each other.

[0023] In this embodiment, the first member 131, the second member 132, and the third member 133 are annular (cylindrical) in shape and are rotatably (rotatably) attached to a round bar-shaped pin 134. The second member 132 and the third member 133 have the same diameter and are integrally formed. The material used to form the roller member 130 is not limited and can be exemplified by metal (including alloys) or resin. Furthermore, the first member 131, the second member 132, and the third member 133 may be formed from different materials or from the same material. For example, the first member 131 may be formed from a metal (including alloys) such as steel, and the second member 132 and the third member 133 may be formed from resin. The second member 132 and the third member 133 are likely to rub against the outer ring member 120 or the support member 140, and forming them from resin can suppress the generation of abnormal noise due to friction.

[0024] Figure 7 is a perspective view of the disassembled support member 140 according to Embodiment 1, taken from the Z+ side. Figure 8 is a perspective view of the disassembled support member 140 according to Embodiment 1, taken from the Z- side. The support member 140 is a member having a holding portion 143 that restricts the circumferential movement of a plurality of roller members 130, and allows radial movement and rotation of the roller members 130, respectively. In this embodiment, the support member 140 comprises a first support member 141 and a second support member 142 so as to support a third member 133 located at one end of a cylindrical roller member 130 and a third member 133 located at the other end, respectively, and each is provided with a holding portion 143 extending in the radial direction.

[0025] The retaining portion 143 is a groove extending radially around the rotation axis 211, and the same number of retaining portions 143 as the roller members 130 of the acceleration / deceleration device 100 are arranged circumferentially. The width of the retaining portion 143 is set to a width into which the third member 133 of the roller member 130 is inserted, allowing the roller member 130 to move radially and allowing the third member 133 to rotate.

[0026] A spacer 144 is placed between the first support member 141 and the second support member 142, and the spacer 144 fixes the first support member 141 and the second support member 142 at an interval corresponding to the length of the roller member 130.

[0027] In this embodiment, the support member 140 rotates around the rotation axis 211 in accordance with the circumferential movement of the roller member 130, which rotates along the inner surface of the outer ring member 120 as a result of the rotation of the cam member 110. The support member 140 is held in the housing 150 so as to be rotatable around the rotation axis 211.

[0028] As shown in Figure 1, the housing 150 is a box-shaped member that houses the cam member 110, the roller member 130, and the support member 140, and holds the outer ring member 120 in a fixed state. In this embodiment, the housing 150 rotatably holds the first shaft body 161 and the second shaft body 162 via the bearing 170.

[0029] The second shaft 162 is a rod-shaped member connected to the support member 140 and extending to the outside of the housing 150. In this embodiment, the second shaft 162 functions as an output shaft that outputs the rotation input to the first shaft 161 in a reduced state by the cam member 110, the outer ring member 120, and the roller member 130. In this embodiment, the second shaft 162 is fixed to the second support member 142 by being inserted into a hole provided in the center of the second support member 142. The second shaft 162 is rotatably mounted to the housing 150 via a bearing 170.

[0030] (Embodiment 2) Another embodiment of the acceleration / deceleration device 100 will be described. Note that parts (components) having the same operation, function, shape, mechanism, and structure as those in Embodiment 1 may be denoted by the same reference numerals and their descriptions may be omitted. Furthermore, the following description will focus on the differences from Embodiment 1, and descriptions of the same aspects may be omitted.

[0031] Figure 9 is a cross-sectional view showing a cross-section of the acceleration / deceleration device 100 according to Embodiment 2. The support member 140 according to Embodiment 2 has a holding portion 143 that restricts the circumferential movement of each of the multiple roller members 130 and allows their radial movement. Specifically, the support member 140 has almost the same overall shape as the support member 140 of Embodiment 1, and the shape of the holding portion 143 is also the same. The difference from Embodiment 1 is that the support member 140 is fixed to the housing 150. Therefore, the support member 140 guides the reciprocating motion of the roller members 130 in the radial direction around the rotation axis 211 and allows the rotation (self-rotation) of the roller members 130.

[0032] In Embodiment 2, the roller member 130 does not rotate (revolve) around the rotation axis 211, but the first member 131 rotates on its own axis due to the rotation of the cam member 110. The multiple roller members 130 reciprocate radially at different timings in accordance with the rotation of the cam member 110, thereby rotating the outer ring member 120, which is rotatably held in the housing 150 via bearings.

[0033] The rotation of the outer ring member 120 is output by a second shaft 162, which is connected to the outer ring member 120 and extends to the outside of the housing 150.

[0034] It should be noted that the present invention is not limited to the embodiments described above. For example, other embodiments of the present invention may be realized by arbitrarily combining the components described herein, or by excluding some of the components. Furthermore, modifications obtained by applying various modifications to the above embodiments that a person skilled in the art could conceive of without departing from the spirit of the present invention, that is, the meaning indicated by the wording in the claims, are also included in the present invention.

[0035] For example, as shown in Figure 10, the roller member 130 includes a first roller member 135 that contacts the cam member 110, and a second roller member 136 that contacts the first roller member 135 and the outer ring member 120. The circumferential movement of the first roller member 135 and the second roller member 136 may be restricted by the holding portion 143, while radial movement may be permitted for each.

[0036] Furthermore, while Embodiments 1 and 2 described the case where the acceleration / deceleration device 100 performs a deceleration function with the first shaft 161 as the input shaft and the second shaft 162 as the output shaft, the acceleration / deceleration device 100 can perform a speed-increasing function by using the first shaft 161 as the output shaft and the second shaft 162 as the output shaft.

[0037] (Summary) The acceleration / deceleration device 100 of the first embodiment includes a cam member 110 having one projection 111, an annular outer ring member 120 arranged concentrically with the rotation axis 211 of the cam member 110 and having a plurality of projections 121 arranged in the circumferential direction that project inward in a curved shape, and a component positioned between the outer ring member 120 and the cam member 110 that is always in contact with the inner circumference of the outer ring member 120 and the outer circumference of the cam member 110, and that rolls along the shape of the inner circumference of the outer ring member 120 as the cam member 110 and the outer ring member 120 rotate relative to each other. The device comprises a number of roller members 130 different from the number of protrusions 121, a support member 140 having a holding portion 143 that restricts the circumferential movement of each of the multiple roller members 130 and allows their radial movement, a housing 150 that houses the cam member 110, the roller members 130, and the support member 140 and to which the outer ring member 120 is fixed, a first shaft 161 connected to the cam member 110 and extending to the outside of the housing 150, and a second shaft 162 connected to the support member 140 and extending to the outside of the housing 150.

[0038] According to the first embodiment, it is possible to provide an acceleration / deceleration device 100 that is quieter than conventional coaxial type acceleration / deceleration devices that transmit rotation by the meshing of gears. Furthermore, it can be easily miniaturized compared to conventional coaxial type acceleration / deceleration devices.

[0039] The acceleration / deceleration device 100 of the second embodiment includes a cam member 110 having one projection 111, an annular outer ring member 120 arranged concentrically with the rotation axis 211 of the cam member 110 and having a plurality of projections 121 arranged circumferentially and projecting inward in a curved shape, and a projection positioned between the outer ring member 120 and the cam member 110, which is always in contact with the inner circumference of the outer ring member 120 and the outer circumference of the cam member 110 and rolls along the shape of the inner circumference of the outer ring member 120 as the cam member 110 and the outer ring member 120 rotate relative to each other. The device comprises a number of roller members 130 different from the number of parts 121, a support member 140 having a holding portion 143 that restricts the circumferential movement of each of the multiple roller members 130 and allows their radial movement, a housing 150 that houses the cam member 110, the roller members 130, and the support member 140 and rotatably holds the outer ring member 120, a first shaft 161 connected to the cam member 110 and extending to the outside of the housing 150, and a second shaft 162 connected to the outer ring member 120 and extending to the outside of the housing 150.

[0040] According to the second embodiment, it is possible to provide an acceleration / deceleration device 100 that is quieter than conventional coaxial type acceleration / deceleration devices that transmit rotation by the meshing of gears. Furthermore, it can be easily miniaturized compared to conventional coaxial type acceleration / deceleration devices.

[0041] The third embodiment of the acceleration / deceleration device includes the first embodiment or the second embodiment, and the roller member 130 comprises a disc-shaped first member 131 that contacts the cam member 110 but does not contact the outer ring member 120, a disc-shaped second member 132 that does not contact the cam member 110 but contacts the outer ring member 120 and has a different diameter from the first member 131, and a disc-shaped third member 133 that is held by the holding portion 143 of the support member 140, wherein the first member 131, the second member 132, and the third member 133 move together in the circumferential direction, radial direction, and rotation axis 211 direction, and the first member 131 and the second member 132 are rotatable relative to each other.

[0042] According to the third aspect, it is possible to suppress as much as possible the sliding between the roller member 130 and the outer ring member 120 and the sliding between the roller member 130 and the cam member 110, which are caused by the difference in the rolling amount of the roller member 130 in the relative rotation of the outer ring member 120 and the cam member 110. Further, by suppressing the sliding, it is possible to suppress the generation of abnormal noise due to the sliding.

[0043] The speed change device of the fourth aspect includes any one of the first aspect to the third aspect. The roller member 130 includes a first roller member 135 that contacts the cam member 110, and a second roller member 136 that contacts the first roller member 135 and the outer ring member 120. The first roller member 135 and the second roller member 136 are each restricted in their circumferential movement by the holding portion 143, and their radial movement is each allowed.

[0044] According to the fourth aspect, the relationship between the rotation direction of the first shaft body 161 and the rotation direction of the second shaft body 162 can be reversed from that of one speed change device 100 in the radial direction of the roller member 130.

[0045] The present invention is useful as a speed change device 100 mounted on a moving body such as an automobile or an industrial machine, for example.

[0046] 100... speed change device, 110... cam member, 111... protrusion, 112... cam contact portion, 113... outer ring contact portion, 119... through hole, 120... outer ring member, 121... protrusion, 130... roller member, 131... first member, 132... second member, 133... third member, 134... pin, 135... first roller member, 136... second roller member, 140... support member, 141... first support member, 142... second support member, 143... holding portion, 144... spacer, 150... housing, 161... first shaft body, 162... second shaft body, 170... bearing, 211... rotating shaft

Claims

1. An acceleration / deceleration device comprising: a cam member having one projection; an annular outer ring member having a plurality of projections arranged circumferentially and concentrically with the rotation axis of the cam member, projecting inward in a curved shape; a number of roller members different from the number of projections, disposed between the outer ring member and the cam member, constantly in contact with the inner circumference of the outer ring member and the outer circumference of the cam member, and rolling along the shape of the inner circumference of the outer ring member as the cam member and the outer ring member rotate relative to each other; a support member having a holding portion that restricts the circumferential movement of the plurality of roller members and allows radial movement of each; a housing that houses the cam member, the roller members, and the support member, and to which the outer ring member is fixed; a first shaft body connected to the cam member and extending to the outside of the housing; and a second shaft body connected to the support member and extending to the outside of the housing.

2. An acceleration / deceleration device comprising: a cam member having one projection; an annular outer ring member having a plurality of projections arranged circumferentially and concentrically with the rotation axis of the cam member, projecting inward in a curved shape; a number of roller members different from the number of projections, disposed between the outer ring member and the cam member, constantly in contact with the inner circumference of the outer ring member and the outer circumference of the cam member, and rolling along the shape of the inner circumference of the outer ring member as the cam member and the outer ring member rotate relative to each other; a support member having a holding portion that restricts the circumferential movement of the plurality of roller members and allows radial movement of each; a housing that houses the cam member, the roller members, and the support member, and rotatably holds the outer ring member; a first shaft connected to the cam member and extending to the outside of the housing; and a second shaft connected to the outer ring member and extending to the outside of the housing.

3. The acceleration / deceleration device according to claim 1 or 2, wherein the roller member comprises a disc-shaped first member that contacts the cam member but does not contact the outer ring member, a disc-shaped second member that does not contact the cam member but contacts the outer ring member and has a different diameter from the first member, and a disc-shaped third member that is held by the holding portion of the support member, the first member, the second member, and the third member move together in the circumferential direction, radial direction, and rotation axis direction, and the first member and the second member are rotatable relative to each other.

4. The acceleration / deceleration device according to claim 1 or 2, wherein the roller member comprises a first roller member that contacts the cam member, and a second roller member that contacts the first roller member and the outer ring member, and the circumferential movement of the first roller member and the second roller member is restricted by the holding portion, and radial movement is permitted for each.

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