Engagement device

Abstract

To provide an engagement device which can keep time required for bringing the device into an engaged state from being long while suppressing reduction in durability.SOLUTION: A dog clutch 10 includes a dog ring 20 and a pair of driven gears 30 which can rotate relative to each other about the same axial line CL. A motive force is transferred by bringing a dog tooth 22 provided on the dog ring 20 and a dog tooth 32 provided on the driven gear 30 into an engaged state. In a radial view about the axial line CL, for at least one of the dog tooth 22 and the dog tooth 32, for example the dog tooth 22, a top face 22t and a connection face 22s connecting an engagement face 22k are in an arc shape, and a connection part P1a of the connection face 22s and the engagement face 22k is cornered.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an engagement device that transmits power by bringing first dog teeth provided on a first rotating member and second dog teeth provided on a second rotating member into meshing state. [Background technology]

[0002] There is known an engagement device that includes a first rotating member and a second rotating member that are rotatable relative to each other around the same axis, and transmits power by meshing first dog teeth provided on the first rotating member with second dog teeth provided on the second rotating member. For example, the engagement device described in Patent Document 1 is such an engagement device. Patent Document 1 discloses that the shapes of the first dog teeth and the second dog teeth are such that the normal direction of the connecting surface that connects the meshing surface and the top surface changes in a stepwise manner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-96759 Summary of the Invention [Problem to be solved by the invention]

[0004] In the engagement device described in Patent Document 1, the connecting surfaces of the first and second dog teeth include tapered surfaces to improve durability. The tapered surfaces make it easier for the tapered surfaces of the first and second dog teeth to collide with each other. This makes it easier to dissipate the collision force when the first and second dog teeth collide in the disengagement direction, thereby reducing the collision force experienced by the first and second dog teeth and improving the durability of the engagement device. On the other hand, the increased likelihood of collision between the tapered surfaces makes it difficult to increase the differential rotation between the first and second rotating members, which allows the first and second dog teeth to mesh. This may result in a longer time required to bring the engagement device into an engaged state. For example, if the engagement device is used in a vehicle transmission, this may result in a longer gear shift period.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide an engagement device that can prevent a decrease in durability while preventing the time required to achieve an engaged state from increasing. [Means for solving the problem]

[0006] The gist of the present invention is an engagement device that includes a first rotating member and a second rotating member that are rotatable relative to each other around the same axis, and transmits power by meshing first dog teeth provided on the first rotating member with second dog teeth provided on the second rotating member, wherein, when viewed radially around the axis, at least one of the first dog teeth and the second dog teeth has a connection surface that connects the top surface and the meshing surface in the form of an arc, and the connection portion between the connection surface and the meshing surface is a corner. [Effects of the Invention]

[0007] According to the engagement device of the present invention, when viewed in the radial direction about the axis, at least one of the first dog tooth and the second dog tooth has a connecting surface connecting the top surface and the meshing surface that is an arc, and the connecting portion between the connecting surface and the meshing surface is a corner. This configuration reduces the collision force (e.g., stress concentration) at the collision point of at least one of the first dog tooth and the second dog tooth having an arc-shaped connecting surface when the first dog tooth and the second dog tooth collide, thereby improving the durability of the engagement device. Furthermore, when the connecting portion is a corner, the shortest distance from the top surface (including the extension of the top surface) to the meshing surface in the movement direction, including the meshing direction and the disengaging direction of the first rotating member and the second rotating member, can be made shorter than when the connecting portion is not a corner. As a result, the relative distance between the first dog tooth and the second dog tooth in the movement direction becomes shorter, so that the meshing surfaces of the first dog tooth and the second dog tooth mesh with each other. This makes it easy to increase the differential rotation between the first rotating member and the second rotating member at which the first dog teeth and the second dog teeth can mesh with each other, thereby preventing a decrease in durability of the engagement device and preventing an increase in the time required to achieve the meshed state. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a dog clutch according to the present invention. FIG. [Figure 2] 2 is a diagram illustrating the shape of dog teeth of the dog clutch shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0010] FIG. 1 is a diagram illustrating the schematic configuration of a dog clutch 10 according to the present invention. The dog clutch 10 comprises a dog ring 20 and a pair of driven gears 30, which are relatively rotatable about the same axis CL. Hereinafter, the circumferential direction about the axis CL will be simply referred to as the "circumferential direction," and the radial direction about the axis CL will be simply referred to as the "radial direction." For example, the dog ring 20 and the driven gear 30 may have a strength [N / m 2 ] is made of a highly durable material, such as steel. "Strength" refers to the degree to which an object can withstand a load. The dog ring 20 is disposed on the axis CL between a pair of driven gears 30.

[0011] The dog ring 20 is disk-shaped. Dog teeth 22 are provided on each surface of the dog ring 20 facing the pair of driven gears 30. The dog teeth 22 are tooth portions that protrude in the direction of the axis CL of the disk-shaped dog ring 20. In this embodiment, five dog teeth 22 are provided at equal angular intervals in the circumferential direction on both surfaces of the dog ring 20 facing each of the pair of driven gears 30. In the dog ring 20, the space between adjacent dog teeth 22 is a groove bottom surface 24m of the groove portion 24 (see FIG. 2).

[0012] Each of the pair of driven gears 30 is disk-shaped. Dog teeth 32 are provided on the surface of the driven gear 30 facing the dog ring 20. The dog teeth 32 are teeth that protrude in the direction of the axis CL from the disk-shaped driven gear 30. In this embodiment, five dog teeth 32 are provided at equal angular intervals in the circumferential direction on both the surface of the driven gear 30 facing the dog ring 20 and the opposite surface. The dog teeth 32 are provided at positions corresponding to the dog teeth 22 so that they can mesh with the dog teeth 22. In each driven gear 30, the space between adjacent dog teeth 32 is a groove bottom surface 34m of the groove portion 34 (see FIG. 2).

[0013] The dog ring 20 is movable in the direction of the axis CL by an actuator such as a shift fork. The movement direction S of the dog ring 20 is the same as the direction of the axis CL. The dog ring 20 can mesh with either one or the other of the pair of driven gears 30, and can also be configured not to mesh with either one or the other of the pair of driven gears 30. When the dog ring 20 is moved in the movement direction S in a direction in which it meshes with the driven gear 30, i.e., in the meshing direction, the dog teeth 22 and the dog teeth 32 are brought into meshing state. When the dog ring 20 is moved in the movement direction S in a direction in which it does not mesh with the driven gear 30, i.e., in the disengaging direction, the dog teeth 22 and the dog teeth 32 are brought into disengagement state. The meshing state is equivalent to an engaged state or a connected state, and the disengaging state is equivalent to a released state or a disconnected state. The movement direction S includes the meshing direction and the disengaging direction.

[0014] When the dog teeth 22 and the dog teeth 32 are disengaged, the transmission of power from the dog ring 20 to the driven gear 30 is cut off. When the dog teeth 22 and the dog teeth 32 are engaged, power is transmitted from the dog ring 20 to the driven gear 30. In this way, the dog clutch 10 is an engagement device that transmits power by bringing the dog teeth 22 and the dog teeth 32 into an engaged state. The dog clutch 10 corresponds to the "engagement device" in the present invention, and the dog ring 20 and the pair of driven gears 30 correspond to the "first rotating member" and the "second rotating member" in the present invention, respectively. The dog teeth 22 and the dog teeth 32 correspond to the "first dog teeth" and the "second dog teeth" in the present invention, respectively.

[0015] FIG. 2 is a diagram illustrating the shapes of the dog teeth 22 and 32 of the dog clutch 10 shown in FIG. 2. FIG. 2 is a cross-sectional view cut in the circumferential direction when the dog teeth 22 and 32 are in an engaged state, i.e., a cross-sectional view viewed in the radial direction. In addition, FIG. 2 shows the shapes of the dog teeth 22 and 32 separately in enlarged views. In the enlarged view of the shape of the dog teeth 22 shown in FIG. 2, the present embodiment is shown by a solid line, and a comparative example is shown by a two-dot chain line. In the following description of FIG. 2, unless otherwise specified, the description will be from the radial view.

[0016] The dog tooth 22 has a plane-symmetrical shape, and the plane of symmetry is a plane extending in the direction of the axis CL and in the radial direction (in this embodiment, any one of five planes equiangularly spaced in the circumferential direction). The dog tooth 22 has a top surface 22t, a pair of meshing surfaces 22k, and a connecting surface 22s. The top surface 22t is the tip surface of the dog tooth 22. The pair of meshing surfaces 22k are both side surfaces of the dog tooth 22 in the circumferential direction. The connecting surfaces 22s are surfaces that connect the top surface 22t and the pair of meshing surfaces 22k. The dog tooth 32 has a plane-symmetrical shape, and the plane of symmetry is a plane extending in the direction of the axis CL and in the radial direction (in this embodiment, any one of five planes equiangularly spaced in the circumferential direction). The dog tooth 32 has a top surface 32t, a pair of meshing surfaces 32k, and a connecting surface 32s. The top surface 32t is the tip surface of the dog tooth 32. The pair of meshing surfaces 32k are both circumferential side surfaces of the dog tooth 32. The connecting surfaces 32s are surfaces that connect the top surface 32t and the pair of meshing surfaces 32k.

[0017] In an engaged state when the rotation directions of the dog ring 20 and the driven gear 30 are forward, one of the pair of meshing surfaces 22k meshes with one of the pair of meshing surfaces 32k. In an engaged state when the rotation directions of the dog ring 20 and the driven gear 30 are reverse, the other of the pair of meshing surfaces 22k meshes with the other of the pair of meshing surfaces 32k. The meshing surface 22k is a surface that transmits power from the dog ring 20 to the driven gear 30 when the dog teeth 22 and the dog teeth 32 are in an engaged state. The meshing surface 32k is a surface that transmits power from the dog ring 20 to the driven gear 30 when the dog teeth 22 and the dog teeth 32 are in an engaged state.

[0018] As described above, the dog teeth 22 and 32 have plane-symmetric shapes. Furthermore, the connecting surfaces 22s and 32s of the dog teeth 22 and 32 have the same shapes. Therefore, the following description will be limited to the shape of one side of the pair of meshing surfaces 22k of the dog teeth 22, and descriptions of the shapes of the other portions will be omitted as appropriate.

[0019] The top surface 22t and the mating surface 22k are each straight. The intersection angle of the extension plane of the top surface 22t and the mating surface 22k and the intersection angle of the extension plane of the top surface 32t and the mating surface 32k are both the same intersection angle θ (<1 / 2π) [rad]. The top surface 22t and the groove bottom surface 34m are parallel. The top surface 32t and the groove bottom surface 24m are parallel. For example, the top surface 22t, the groove bottom surface 34m, the top surface 32t, and the groove bottom surface 24m are all surfaces perpendicular to the axis CL.

[0020] The connection surface 22s has, for example, an arc shape with a curvature radius R [m] from the center of curvature O1a. The curvature radius R is determined experimentally or by design so that the durability of the dog clutch 10 is within an acceptable range. The larger the curvature radius R, the better the durability, but the greater the distance D1a (described below) becomes. Here, the connection portion between the connection surface 22s and the mating surface 22k is referred to as the connection portion P1a, and the connection portion between the connection surface 22s and the top surface 22t is referred to as the connection portion Q1a. The connection portion P1a corresponds to the "connection portion between the connection surface and the mating surface" in this invention. Both the connection portion P1a and the connection portion Q1a are corners. "Being a corner" means that the mating surface or the top surface is not tangentially connected to the arc-shaped connecting surface, and the intersection angle between the tangent to the connecting surface at the connecting portion (in the case of the dog tooth 22, the tangent L1a or the tangent L2a) and the mating surface or the top surface (in the case of the dog tooth 22, the mating surface 22k or the top surface 22t) is less than π [rad]. In this embodiment, the central angle φ1 [rad] of the arc of the connecting surface 22s is less than 1 / 2π [rad]. "Tangentially connected" means that the tangent to the connecting surface at the connecting portion and the mating surface or the top surface are connected in the same direction. "Not tangentially connected" means that the tangent to the connecting surface at the connecting portion and the mating surface or the top surface are connected so as to intersect. Here, the shortest distance from the top surface 22t (including the extension of the top surface 22t) to the engagement surface 22k in the movement direction S, i.e., the distance from the top surface 22t (including the extension of the top surface 22t) to the connection point P1a, is referred to as distance D1a [m].

[0021] The comparative example in the enlarged view of the shape of the dog teeth 22 shown in FIG. 2 has substantially the same shape as this embodiment, so only the differences will be explained.

[0022] The connecting surface 26s has an arc shape with a curvature radius R from the center of curvature O2a. Here, the connection portion between the connecting surface 26s and the mating surface 22k is referred to as the connecting portion P2a, and the connection portion between the connecting surface 26s and the top surface 22t is referred to as the connecting portion Q2a. Neither the connecting portion P2a nor the connecting portion Q2a is a corner. That is, the mating surface 22k and the top surface 22t are both tangentially connected to the arc-shaped connecting surface 26s. In this comparative example, the central angle φ2 [rad] of the arc of the connecting surface 26s exceeds 1 / 2π [rad]. Here, the distance from the top surface 22t (including the extension plane of the top surface 22t) to the connecting portion P2a in the movement direction S is referred to as the distance D2a [m].

[0023] In this embodiment and the comparative example, the connection surfaces 22s and 26s have the same radius of curvature R, but the distance D1a in this embodiment is shorter than the distance D2a in the comparative example. This is because neither the connection portion P2a nor the connection portion Q2a in the comparative example is a corner, whereas both the connection portion P1a and the connection portion Q1a in this embodiment are corners.

[0024] The connecting surface 32s has an arc shape with a curvature radius R [m] from the center of curvature O1b, for example. For example, if the dog ring 20 and the driven gear 30 are made of the same material, the connecting surface 22s and the connecting surface 32s are preferably made the same in curvature radius as in this embodiment. Here, the connecting portion between the connecting surface 32s and the meshing surface 32k is referred to as the connecting portion P1b, and the connecting portion between the connecting surface 32s and the top surface 32t is referred to as the connecting portion Q1b. The connecting portion P1b corresponds to the "connecting portion between the connecting surface and the meshing surface" in this invention. Here, the distance from the top surface 32t (including the extension of the top surface 32t) to the connecting portion P1b is referred to as the distance D1b.

[0025] The base end of the dog tooth 32 is shaped so that when the dog tooth 22 and the dog tooth 32 are in an engaged state, a gap is created between the connection surface 22s and the opposing base end of the dog tooth 32. Similarly, the base end of the dog tooth 22 is shaped so that when the dog tooth 22 and the dog tooth 32 are in an engaged state, a gap is created between the connection surface 32s and the opposing base end of the dog tooth 22.

[0026] According to this embodiment, the dog clutch 10 includes a dog ring 20 and a driven gear 30 that are rotatable relative to each other about the same axis CL. The dog teeth 22 provided on the dog ring 20 and the dog teeth 32 provided on the driven gear 30 are meshed to transmit power. When viewed in the radial direction, the connection surface 22s is arc-shaped, and the connection sites P1a and Q1a are corners, while the connection surface 32s is arc-shaped, and the connection sites P1b and Q1b are corners. Because the connection surfaces 22s and 32s are each arc-shaped, when the dog teeth 22 and 32 collide, the arc-shaped connection surface 22s and the arc-shaped connection surface 32s come into contact with each other in a circumscribing manner. This reduces stress concentration at the collision points between the dog teeth 22 and 32, improving the durability of the dog clutch 10. Furthermore, when the connection portions P1a and Q1a are corners, the distance D1a can be shortened compared to when they are not corners. When the connection portions P1b and Q1b are corners, the distance D1b can be shortened compared to when they are not corners. As a result, the meshing surfaces 22k and 32k mesh with each other simply by the short distances D1a and D1b between the dog teeth 22 and 32 in the movement direction S. This tends to increase the differential rotation between the dog ring 20 and the driven gear 30, which allows the dog teeth 22 and 32 to mesh with each other. In other words, even if the differential rotation between the dog ring 20 and the driven gear 30 is large, the dog ring 20 and the driven gear 30 are easily meshed with each other. Therefore, the dog clutch 10 is prevented from decreasing in durability and from taking a long time to mesh with each other. For example, when the dog clutch 10 is used in a vehicle transmission, the gear shift period is prevented from becoming long.

[0027] The above-described embodiments of the present invention are merely examples, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[0028] In the above-described embodiment, the dog teeth 22 and 32 are both plane-symmetrical, and the connecting surfaces 22s and 32s of the dog teeth 22 and 32 have the same shapes. However, the present invention is not limited to this. For example, the dog teeth 22 and 32 do not have to be plane-symmetrical. For example, the radii of curvature of the connecting surfaces 22s on both sides of the dog tooth 22 in the circumferential direction may be different from each other, or one of the connecting surfaces 22s may be arc-shaped and the other may be tapered when viewed in the radial direction. For example, the connecting surfaces 22s and 32s of the dog teeth 22 and 32 do not have to be the same from each other when viewed in the radial direction. For example, the radii of curvature of the connecting surfaces 22s and 32s may be different from each other, or one of the connecting surfaces 22s and 32s may be arc-shaped and the other may be tapered. In dog teeth 22 and 32, at locations where the connection surfaces 22s, 32s are arcs when viewed radially and the connection portions P1a, P1b are corners, the dog clutch 10 is prevented from increasing in time required to achieve an engaged state while suppressing a decrease in durability at those locations.

[0029] In the above-described embodiment, the connection portions P1a, Q1a, P1b, and Q1b are each a corner when viewed in the radial direction, but the present invention is not limited to this. For example, at least one of the connection portions P1a and P1b may be a corner. This allows at least one of the distances D1a and D1b to be shortened. Therefore, when the rotation directions of the dog ring 20 and the driven gear 30 are either forward or reverse, the differential rotation between the dog ring 20 and the driven gear 30, at which the dog teeth 22 and 32 can mesh with each other, is likely to be increased. Therefore, the time required for the dog clutch 10 to be brought into meshed state is prevented from becoming long.

[0030] In the above-described embodiment, the dog ring 20 is disposed between a pair of driven gears 30 and is capable of meshing with either one or the other of the pair of driven gears 30, but the present invention is not limited to this embodiment. For example, the present invention is also applicable to an embodiment in which the dog ring 20 faces one driven gear 30, and the dog teeth 22 and the dog teeth 32 are provided only on the surfaces where the dog ring 20 and one driven gear 30 face each other. [Explanation of symbols]

[0031] 10: dog clutch (engagement device), 20: dog ring (first rotating member), 22: dog tooth (first dog tooth), 22k: meshing surface, 22s: connecting surface, 22t: top surface, 30: driven gear (second rotating member), 32: dog tooth (second dog tooth), 32k: meshing surface, 32s: connecting surface, 32t: top surface, CL: axis, P1a: connecting portion (connecting portion between connecting surface and meshing surface), P1b: connecting portion (connecting portion between connecting surface and meshing surface)

Claims

[Claim 1] An engagement device comprising a first rotating member and a second rotating member that are rotatable relative to each other around the same axis, wherein first dog teeth provided on the first rotating member and second dog teeth provided on the second rotating member are brought into meshing engagement with each other to transmit power, When viewed in a radial direction about the axis, at least one of the first dog tooth and the second dog tooth has a connecting surface that connects a top surface and a meshing surface, the connecting surface being an arc, and the connecting portion between the connecting surface and the meshing surface is a corner. An engagement device characterized by:

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