Ratchet type one-way clutch

Abstract

To provide a ratchet type one-way clutch capable of improving durability without requiring complicated assembling work.SOLUTION: A claw member 3 has an inner diameter side surface 45 in contact with a teeth portion 5 when an inner ring 9 idles with respect to an outer ring 7. When viewed from a center axis C direction of the inner ring 9, assuming a contact point between the inner diameter side surface 45 and the teeth portion 5 as a contact P, a straight line vertically intersecting the center axis C and passing through the contact P as a straight line A, a straight line vertically intersecting the straight line A, passing through the contact P and orthogonal to the center axis C direction as a straight line B, a tangent at the contact point P about the inner diameter side surface 45 as a tangent T, and the size of an angle between the straight line B and the tangent T as α, the range of α satisfies a predetermined conditional expression.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ratchet type one-way clutch used as a torque transmission mechanism in vehicles, industrial machines, etc. [Background technology]

[0002] BACKGROUND ART In recent years, ratchet one-way clutches have been increasingly used as one-way clutches for use in electric drive devices and the like because of their reliable engagement and controllability.

[0003] In ratchet one-way clutches used in electric drive devices, for example, when an electric motor is used as a power source, there is a concern that the durability of the parts will decrease due to high-speed rotation. Patent Documents 1 and 2 describe ratchet one-way clutches with improved durability.

[0004] Patent Document 1 describes a ratchet-type one-way clutch in which the behavior of the spring is stabilized by supporting the spring using a cylindrical support member, thereby reducing wear and breakage of the spring and improving durability. Patent Document 2 describes a ratchet-type one-way clutch in which a coil spring is attached to an outer ring via a spring seat, so that one end of the spring is supported by the flat portion of the spring seat, thereby suppressing the vibration of the spring and improving durability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-110707 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-101758 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the ratchet one-way clutches of Patent Documents 1 and 2, a part for holding the spring is added to the conventional components to stabilize the behavior of the spring, thereby suppressing damage to the components and improving the durability of the ratchet one-way clutch.As a result, with the ratchet one-way clutches of Patent Documents 1 and 2, there is a concern that the number of parts increases and the assembly work becomes more complicated, resulting in increased costs.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a ratchet type one-way clutch that can improve durability without requiring complicated assembly work. [Means for solving the problem]

[0008] In order to solve the above problems, the ratchet one-way clutch according to the present invention comprises: a first annular member; a second annular member arranged coaxially with and rotatable relative to the first annular member; a ratchet mechanism that can engage the first annular member with the second annular member so as to transmit torque; The ratchet mechanism is configured to of a plurality of teeth provided on a peripheral surface facing the annular member in a radial direction, the teeth extending in an axial direction and having a substantially rectangular cross-sectional shape; a plurality of pawl members provided on the second annular member radially opposite the toothed portion, which engage with the toothed portion to lock relative rotation of the first annular member with respect to the second annular member in a first rotational direction and allow relative rotation in a second rotational direction; a plurality of elastic members that bias the plurality of claw members in the direction of engaging with the tooth portions, the pawl member has a curved surface that comes into contact with the tooth portion when the first annular member rotates relative to the second annular member in the second rotation direction, the curved surface faces the tooth portion in the radial direction and is formed to bulge toward the tooth portion, When viewed from the direction of the central axis of the first annular member, the point of contact between the curved surface and the tooth portion is defined as point of contact P, a straight line that intersects the central axis perpendicularly and passes through point of contact P is defined as line A, a straight line that intersects line A perpendicularly, passes through point of contact P and is perpendicular to the direction of the central axis is defined as line B, a tangent to the curved surface at point of contact P is defined as line T, and the size of the angle formed by line B and tangent T is defined as α.The curved surface is characterized in that, regardless of the position of point of contact P on the curved surface, the range of α satisfies the following conditional expression. 10°<α<15° [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a ratchet type one-way clutch that can improve durability without requiring complicated assembly work. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a front view showing the main part of a ratchet one-way clutch according to an embodiment, showing the state in which the pawl members and the teeth are not engaged with each other. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a ratchet type one-way clutch according to an embodiment of the present invention will be described with reference to the drawings. First, the directions related to the ratchet one-way clutch in this embodiment will be defined. In this embodiment, the axial direction, radial direction, and circumferential direction refer to the axial direction, radial direction, and circumferential direction relative to the central axis C of the ratchet one-way clutch, i.e., the central axis C of the outer ring and the inner ring. Furthermore, with regard to the axial direction, the front side of the paper in Fig. 1 is one axial side or front side, and the back side of the paper is the other axial side. With regard to the circumferential direction, the direction rotating clockwise as viewed on the paper in Fig. 1 is one circumferential side, and the direction rotating counterclockwise as viewed on the paper is the other circumferential side.

[0012] Regarding the rotation direction of a ratchet clutch, the rotation of the outer ring and the rotation of the inner ring are relative. For example, if the inner ring can rotate clockwise, the outer ring can also rotate counterclockwise. Also, even if the inner ring and the outer ring rotate in the same direction, if the rotation speeds of the outer ring and the inner ring are different, it can be said that the outer ring and the inner ring are rotating in one direction relative to each other.

[0013] FIG. 1 is a front view showing the main part of a ratchet type one-way clutch 1 according to the embodiment as viewed from one axial side, showing the state in which the pawl members 3 and the teeth 5 are not engaged with each other. The ratchet type one-way clutch 1 according to this embodiment has an overall annular shape as viewed in the axial direction, similar to the shape shown in Fig. 1 of Patent Document 2, and is provided with a plurality of pawl members 3 and a plurality of teeth 5. Fig. 1 shows only one pawl member 3 and its surrounding area.

[0014] The ratchet-type one-way clutch 1 of this embodiment has an annular outer ring 7, an annular inner ring 9 arranged radially inward of the outer ring 7 coaxially with the outer ring 7 and rotatable relative to the outer ring 7, and a ratchet mechanism that enables torque transmission between the outer ring 7 and the inner ring 9.

[0015] A large number of teeth 5, which protrude radially outward and extend in the axial direction, are formed at equal intervals in the circumferential direction on the outer peripheral surface of the inner ring 9. Circumferentially adjacent teeth 5 form a space 11 of a predetermined circumferential width. The cross-sectional shape of each tooth 5, as viewed from the axial direction, is generally rectangular, and the tooth 5 has a surface 13 on one circumferential side, a surface 15 on the other circumferential side, and an outer diameter side surface 17 that circumferentially connects the outer diameter side end of the surface 13 on one circumferential side to the outer diameter side end of the surface 15 on the other circumferential side. The outer diameter side surface 17 of each tooth 5 is formed as a flat surface parallel to the axial direction or a curved surface that bulges slightly radially outward. The tooth 5 extends from one axial end to the other axial end of the inner ring 9.

[0016] A shaft hole (not shown) is formed in the center of the inner ring 9, and a drive shaft (not shown) of, for example, an electric motor or the like is fitted into the shaft hole.

[0017] A plurality of pawl member holding portions 21 are formed at predetermined intervals in the circumferential direction on the inner peripheral portion of the outer ring 7. Each pawl member holding portion 21 is a recess that opens radially inward and is recessed radially outward. A first recess 23 and a second recess 25 are further formed in the bottom portion of each pawl member holding portion 21, in this order from one circumferential side to the other circumferential side. The first recess 23 is recessed toward one circumferential side and radially outward. The second recess 25 is recessed toward the other circumferential side and radially outward.

[0018] The claw member 3 has a columnar portion 41 extending in the axial direction and a claw portion 43 extending from the columnar portion 41 toward the other circumferential direction. The columnar portion 41 and the claw portion 43 are integrally formed. The claw portion 43 has a predetermined radial thickness and includes an inner diameter side surface 45, an outer diameter side surface 47, and a tip surface 49 that connects the other circumferential end of the inner diameter side surface 45 to the other circumferential end of the outer diameter side surface 47 in a substantially radial direction. The inner diameter side surface 45 of the claw portion 43 faces the tooth portion 5 of the inner ring 9 in the radial direction. The columnar portion 41 of the claw member 3 is rotatably held in the first recess 23 of the claw member holder 21. That is, the claw member 3 is held in the first recess 23 so that the claw portion 43 can swing radially around the columnar portion 41.

[0019] A coil spring 51 is disposed in the second recess 25 of the claw member holding portion 21, and biases the claw member 3 toward the inner ring 9. Specifically, the spring 51 contacts the outer diameter surface 47 of the claw portion 43 of the claw member 3, and biases the claw portion 43 toward the inner ring 9. With this configuration, the claw member 3 is constantly biased by the spring 51 in the direction of meshing with the tooth portion 5.

[0020] In this way, one pawl member holder 21 holds a set of pawl member 3 and spring 51. A ratchet mechanism is formed by the tooth portion 5 of the inner ring 9 and the pawl member 3 and spring 51 held by the pawl member holder 21. In this embodiment, a coil-shaped spring 51 is used, but the shape of the spring 51 is not limited to this.

[0021] A spline (not shown) is formed on the outer periphery of the outer ring 7, and a shaft member (not shown) connected to a driven device (not shown) to which a driving force such as an electric motor (not shown) is transmitted is fitted into the spline. Alternatively, the outer ring 7 can be fixed, and the ratchet one-way clutch 1 can be used as a backstop.

[0022] In the ratchet type one-way clutch 1 of this embodiment, as shown in FIG. 1, when the inner ring 9 rotates clockwise, the relative rotation of the inner ring 9 with respect to the outer ring 7 is fixed, and when the inner ring 9 rotates counterclockwise, the inner ring 9 rotates freely with respect to the outer ring 7.

[0023] Specifically, when the inner ring 9 rotates clockwise, the multiple pawl members 3 of the outer ring 7 each mesh with the toothed portions 5 of the inner ring 9. The meshing between the pawl members 3 and the toothed portions 5 is achieved by, specifically, the engagement of the tip surfaces 49 of the pawl portions 43, which are depressed into the spaces 11 between the toothed portions 5 by the biasing force of the springs 51, with the surfaces 13 on one circumferential side of the toothed portions 5. Thus, the surfaces 13 on one circumferential side of the toothed portions 5 of the inner ring 9 constitute the meshing surfaces of the toothed portions 5 that mesh with the pawl members 3 of the outer ring 7. In the following description, the surfaces 13 on one circumferential side of the toothed portions 5 will also be referred to as the "meshing surfaces 13 of the toothed portions 5." The meshing of the pawl members 3 with the toothed portions 5 causes the outer ring 7 and inner ring 9 to rotate together, transmitting torque from the inner ring 9 to the outer ring 7. Alternatively, if the outer ring 7 is fixed, the rotation of the inner ring 9 relative to the outer ring 7 is fixed, thereby functioning as a backstop that prevents the inner ring 9 from rotating in the clockwise direction.

[0024] On the other hand, when the inner ring 9 rotates counterclockwise, the multiple pawl members 3 do not mesh with the teeth 5 of the inner ring 9, and the inner ring 9 rotates freely relative to the outer ring 7. Specifically, the pawl members 43 of the pawl members 3 are pushed radially outward by the teeth 5 of the inner ring 9 against the biasing force of the spring 51, allowing the inner ring 9 to rotate. In this state, torque is not transmitted from the inner ring 9 to the outer ring 7. In this way, the ratchet mechanism switches the inner ring 9 and the outer ring 7 between a torque transmitting state and a torque non-transmitting state.

[0025] The ratchet one-way clutch 1 according to this embodiment has a structure in which the pawl members 3 exhibit stable behavior when the inner ring 9 rotates counterclockwise and spins freely relative to the outer ring 7. The configuration of the ratchet mechanism of the ratchet one-way clutch 1 according to this embodiment will be described in further detail below. Note that the following description will be given taking as an example a case in which the inner ring 9 rotates relative to the outer ring 7.

[0026] In the ratchet-type one-way clutch 1 of this embodiment, the inner diameter side surfaces 45 of the pawl portions 43 of the pawl members 3 are formed as curved surfaces that bulge radially inward. Specifically, the inner diameter side surfaces 45 of the pawl portions 43 are formed as curved surfaces that have a cross-sectional shape, as viewed from the axial direction, that bulge radially inward in an arc-like shape. That is, the inner diameter side surfaces 45 of the pawl portions 43 are partially cylindrical outer peripheral surfaces. When the inner ring 9 rotates counterclockwise in FIG. 1 from a state in which the pawl portions 43 of the pawl members 3 are engaged with the toothed portions 5, i.e., a state in which the tip surfaces 49 of the pawl portions 43 are engaged with the engaging surfaces 13 of the toothed portions 5, the ridge portions 61 between the outer diameter side surface 17 and the other circumferential side surface 15 of the toothed portions 5 of the inner ring 9 slide on the inner diameter side surfaces 45 of the pawl portions 43 from one circumferential side to the other circumferential side. As the ridge 61 moves toward the other side in the circumferential direction on the inner diameter side surface 45 of the claw portion 43, the claw portion 43 is pushed up radially outward.

[0027] As the inner ring 9 continues to rotate counterclockwise, the toothed portions 5 move in the other circumferential direction relative to the claw portions 43, and the ridge portions 61 of the toothed portions 5 slide to the tips of the inner diameter surface 45 of the toothed portions 43 on the other circumferential side. As the toothed portions 5 then move in the other circumferential direction relative to the claw portions 43, the tips of the claw portions 43, i.e., the other circumferential ends of the inner diameter surface 45 of the claw portions 43, slide relatively in the one circumferential direction on the outer diameter surface 17 of the toothed portions 5. Once the other circumferential end of the inner diameter surface 45 of the claw portions 43 slides to one circumferential end of the outer diameter surface 17 of the toothed portions 5, it then falls into the spaces 11 between the toothed portions 5 due to the biasing force of the springs 51. That is, the tips of the claw portions 43 fall into the spaces 11 between the toothed portions 5. The claw members 3 and the toothed portions 5 repeat this behavior while the inner ring 9 is rotating counterclockwise.

[0028] Here, when viewed from the axial direction, when the ratchet one-way clutch 1 is rotating freely, that is, when the inner ring 9 is rotating freely relative to the outer ring 7, the point of contact between the inner diameter surface 45 of the pawl portion 43 and the ridge portion 61 of the tooth portion 5 or the outer diameter surface 17 is defined as point of contact P, and a line that intersects perpendicularly with the central axis C of the inner ring 9 and passes through point of contact P is defined as line A. Furthermore, a line that intersects perpendicularly with line A, passes through point of contact P, and is perpendicular to the direction of the central axis C is defined as line B. Furthermore, a line tangent to the inner diameter surface 45 of the pawl portion 43 at point of contact P is defined as line T, and the size of the angle formed by line B and line T is defined as α. Note that lines A, B, and T in FIG. 1 are all imaginary lines.

[0029] The ratchet one-way clutch 1 of this embodiment is configured so that the range of α satisfies the following conditional expression (1). (1) 10°<α<15°

[0030] That is, the ratchet one-way clutch 1 of this embodiment is configured so that the shape of the inner diameter side surface 45 of the pawl member 3 that comes into contact with the tooth portion 5 satisfies conditional formula (1). As described above, the position of the contact point P on the inner diameter side surface 45 of the pawl member 3 changes as the inner ring 9 rotates, but the ratchet one-way clutch 1 of this embodiment is configured so that the conditional formula (1) is satisfied regardless of the position of the contact point P on the inner diameter side surface 45. In detail, the shape of the inner diameter side surface 45 of the pawl member 3 is configured so that the radius of curvature and the circumferential length satisfy conditional formula (1).

[0031] In the ratchet one-way clutch 1 of this embodiment, the shape of the inner diameter side surface 45 of the pawl member 3 satisfies conditional formula (1), thereby reducing radial oscillation of the pawl member 3 caused by continuous contact between the pawl member 3 and the multiple teeth 5 during idling. With this configuration, the ratchet one-way clutch 1 of this embodiment stabilizes the behavior of the spring 51 during idling, preventing damage to the spring 51 and parts surrounding the spring 51 and improving durability. Furthermore, because the behavior of the spring 51 is stabilized, it becomes possible to apply a spring of a conventional structure to the high-speed ratchet one-way clutch 1.

[0032] Furthermore, if the shape of the inner diameter side surface 45 of the claw member 3 falls outside the range of conditional formula (1), the radial oscillation of the claw member 3 due to continuous contact between the claw member 3 and the tooth portion 5 during idling becomes large, making it difficult to stabilize the behavior of the spring 51, which is undesirable.

[0033] As described above, according to this embodiment, it is possible to realize a ratchet type one-way clutch 1 that does not require complicated assembly work and that can further suppress increases in costs. The present invention is not limited to the above embodiment and can be modified as appropriate. For example, the present invention can be applied to a ratchet one-way clutch in which the pawl members 3 are provided on the outer periphery of the inner ring 9 and the teeth portion 5 are provided on the inner periphery of the outer ring 7. [Explanation of symbols]

[0034] 1 Ratchet type one-way clutch 3 Claw member 5 Tooth 7 Outer ring 9. Inner Circle 13 Circumferential surface on one side 15 Other circumferential surface 17 Outer diameter surface 21 Claw member holding part 41 Cylinder 43 Claw 45 Inner diameter surface 51 Spring

Claims

[Claim 1] a first annular member; a second annular member arranged coaxially with and rotatable relative to the first annular member; a ratchet mechanism that can engage the first annular member with the second annular member so as to transmit torque; The ratchet mechanism includes a plurality of teeth that are provided on a peripheral surface of the first annular member that faces the second annular member in a radial direction, extend in an axial direction, and have a substantially rectangular cross section; a plurality of pawl members provided on the second annular member radially opposite the toothed portion, which mesh with the toothed portion to lock relative rotation of the first annular member with respect to the second annular member in a first rotational direction and allow relative rotation in a second rotational direction; a plurality of elastic members that bias the plurality of claw members in the direction of engaging with the tooth portions, the pawl member has a curved surface that comes into contact with the tooth portion when the first annular member rotates relative to the second annular member in the second rotation direction, the curved surface faces the tooth portion in the radial direction and is formed to bulge toward the tooth portion, 1. A ratchet one-way clutch comprising: a first annular member having a first tooth portion and a second tooth portion; a first annular member having a first tooth portion and a second tooth portion; a second annular member having a second tooth portion and a second tooth portion; a first annular member having a second tooth portion and a second tooth portion; a second annular member having a second tooth portion and a second tooth portion; a first annular member having a second tooth portion and a second tooth portion; a second annular member having a second tooth portion and a second tooth portion; a first annular member having a second tooth portion and a second tooth portion; a second annular member having a first ... １０°＜α＜１５°

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