Power transmission

Abstract

To provide a power transmission device that can suppress emission of noise due to backlash while suppressing a cost increase.SOLUTION: A power transmission device 10 includes: an output shaft 23 including a helical gear; a transfer clutch 70 fitted to the output shaft 23; and a sleeve body 90 for connecting the transfer clutch 70 to the output shaft 23. The sleeve body 90 is fitted to an outer peripheral surface of the output shaft 23 with spline fitting. A tapered part 90b is formed at an inner peripheral surface of the sleeve body 90.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a connection structure for components that constitute a power transmission device. [Background technology]

[0002] Conventionally, power transmission devices have been disclosed in which a clutch is connected to a shaft by spline engagement. For example, Patent Document 1 listed below discloses a clutch structure connected to an input shaft by spline engagement. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 58-96115 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, in a power transmission device in which a shaft (e.g., an output shaft) and a clutch are connected by spline engagement, such as the power transmission device of Patent Document 1, backlash exists in the splines formed between the shaft and another member (e.g., a sleeve). Therefore, when the shaft is subjected to rotational fluctuations in a drive source such as an engine in a state in which another member such as a sleeve is not contributing to power transmission, the backlash of the splines may cause teeth rattling noise (a rattling sound caused by members coming into contact with each other) (noise caused by teeth rattling between splines). That is, in conventional power transmission devices, the clutch is attached to the shaft by spline engagement, and therefore teeth rattling noise may occur due to the backlash of the splines during rotational fluctuations.

[0005] In order to suppress the occurrence of such teeth rattle noise, a method of fixing the end of the sleeve with a lock nut or the like can be considered. However, using a lock nut or the like increases the number of parts for connecting the sleeve and the shaft, which increases costs and also increases the axial length.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a power transmission device that can suppress the generation of abnormal noise caused by backlash while suppressing an increase in cost. [Means for solving the problem]

[0007] Here, the inventors have conducted extensive research and have found that the above-mentioned tooth rattle noise can be suppressed by providing a contact portion that contacts a connecting member (e.g., a sleeve member) on one axial side of a shaft body (e.g., an output shaft) equipped with a helical gear. More specifically, a thrust force acting on the helical gear provided on the shaft body applies friction to the connecting member (e.g., a sleeve member), and the two parts (shaft body and connecting member) that are spline-fitted can rotate together. This makes it possible to restrict the movement of the shaft body and the connecting member due to the backlash. As a result, the generation of noise due to spline rattle between the two parts can be suppressed.

[0008] Based on the above-mentioned findings, the inventors conducted further intensive research and came to the finding that when the thrust force acting on the helical gear mounted on the shaft is small, the frictional force generated due to the thrust force also becomes small, and the effect of suppressing noise generation due to spline tooth strike as described above becomes lower.

[0009] (1) The power transmission device of the present invention, provided based on the above-mentioned findings, is a power transmission device having a shaft body equipped with a helical gear and a clutch device attached to the shaft body, and is characterized in that it has a connecting member connecting the clutch device to the shaft body and one or more biasing members, wherein the connecting member is attached to the outer peripheral surface of the shaft body by spline fitting, the shaft body has an abutment portion that abuts against the connecting member from one axial side of the helical gear, and the biasing member applies a biasing force directly or indirectly to either one or both of the connecting member and the shaft body in a direction in which the abutment portion and the connection portion approach each other in the axial direction.

[0010] The power transmission device of the present invention, by being configured as described above in (1), can generate frictional force at a portion other than the portion connected by the spline (spline fitting portion) to connect (fix) the shaft body and the connecting member, thereby suppressing backlash of the spline. That is, in the power transmission device of the present invention, in addition to the spline fitting portion, the biasing force of the biasing member brings the abutment portion and the connecting member into contact while applying a pressing force between them. This allows the power transmission device of the present invention to restrict the movement of the backlash between the shaft body and the connecting member. Therefore, the power transmission device of the present invention can effectively suppress the generation of noise due to spline tooth strike in a situation where the thrust force acting on the helical gear provided on the shaft body is small.

[0011] (2) In the power transmission device of the present invention described above, it is preferable that the connecting member abuts against the abutment portion on one side of the axial direction, and a part or all of the biasing member applies a biasing force to the connecting member in a direction toward one side in the axial direction on the other side of the axial direction.

[0012] By configuring the power transmission device of the present invention as described above in (2), the connecting member is pressed against the abutment portion on one side in the axial direction due to the influence of the biasing force applied by the biasing member to the connecting member on the other side in the axial direction, so that the power transmission device of the present invention can effectively suppress the generation of noise due to spline tooth strike even in a situation where the thrust force acting on the helical gear provided on the shaft is small.

[0013] (3) In the power transmission device of the present invention described above, it is preferable that a part or the whole of the biasing member is formed of a compression spring that expands and contracts along an outer circumferential surface of the shaft body.

[0014] By configuring the power transmission device of the present invention as described above in (3), the compression spring constituting the biasing member is guided by the shaft body and reliably expands and contracts along the axial direction. This allows the power transmission device of the present invention to reliably apply an appropriate amount of biasing force to the connecting member. Therefore, in the power transmission device of the present invention, the connecting member is firmly pressed against the abutment portion by the biasing force applied by the biasing member. Therefore, the power transmission device of the present invention can more reliably suppress the generation of noise due to spline tooth strike, even in a situation where the thrust force is small.

[0015] (4) The power transmission device of the present invention described above may be characterized in that a part or the whole of the biasing member is formed of a wave spring.

[0016] The power transmission device of the present invention, by being configured as described above in (4), can generate a sufficient biasing force while being compact in the axial direction of the shaft compared to a case where a compression spring or the like is used as a biasing member. This allows the power transmission device of the present invention to have a compact configuration in the axial direction.

[0017] (5) The power transmission device of the present invention described above may be characterized in that the abutment portion is tapered, and the connecting member has a tapered portion formed in a tapered shape at a portion of its inner surface that abuts against the abutment portion.

[0018] The power transmission device of the present invention has the configuration described above in (5), and by connecting the tapered portion forming the abutment portion and the portion of the connecting member where the tapered portion is provided, in addition to the portion connected by the spline (spline fitting portion), it is possible to restrict the movement due to backlash between the shaft body and the connecting member. As a result, the power transmission device of the present invention can further reduce the generation of noise due to spline tooth rattle.

[0019] Furthermore, by configuring the power transmission device of the present invention as described above in (3), it is possible to apply a frictional force proportional to the input torque to the shaft body. More specifically, a frictional force is generated between the connection member and the shaft body due to the thrust force that the helical gear receives when rotating. In other words, when the torque is large, a large frictional force can be applied. Therefore, even if the torque on the input side increases, a frictional force corresponding to the input torque is generated, so that even if torque fluctuations occur, both parts (shaft body and connection member) can be firmly connected (fixed) without slipping.

[0020] (6) The power transmission device of the present invention described above may be characterized in that, when the axis of the shaft is taken as a reference line and the gradient with respect to the reference line is taken as an inclination angle, the inclination angle of the tapered portion is smaller than the inclination angle of the abutment portion.

[0021] By configuring the power transmission device of the present invention as described above in (6), the inclination angle of the tapered portion is smaller than the portion where the tapered portion of the shaft comes into contact (the abutment portion), and the abutment portion and the tapered portion come into contact more strongly toward the entrance (helical gear side) of the connecting member. Furthermore, by configuring the power transmission device of the present invention as described above, when a thrust load is input, the opening of the connecting member opens slightly, and the entire surface of the tapered portion comes into contact with the abutment portion. In other words, when a force in the thrust direction acts on the shaft, the entrance side of the tapered portion comes into contact with the abutment portion first. This makes it possible to generate a high frictional force between the tapered portion and the abutment portion. As a result, the shaft and the connecting member can be more reliably positioned to prevent slippage.

[0022] (7) The power transmission device of the present invention described above may be characterized in that the shaft body is supported by a bearing member on the other side of the helical gear in the axial direction, and the biasing member is provided between the bearing member and the helical gear.

[0023] By configuring the power transmission device of the present invention as described above in (7), the bearing member for supporting the shaft body can be used as a seat to reliably apply a biasing force from the biasing member to the shaft body.

[0024] (8) The power transmission device of the present invention described above may be characterized in that the connection member is formed of a sleeve-shaped member through which the shaft body can be inserted.

[0025] The power transmission device of the present invention has the above-mentioned configuration (8), which allows the clutch device to be connected to the shaft with a simple structure. Also, the power transmission device of the present invention has the above-mentioned configuration, which makes it easy to form the tapered portion and the spline. Effect of the Invention

[0026] According to the present invention, it is possible to realize a power transmission device that solves the above-mentioned problems. [Brief description of the drawings]

[0027] [Figure 1] 1 is a cross-sectional view showing a speed change unit according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view showing the rear side of the speed change unit in FIG. 1. [Diagram 3] 2 is an enlarged view showing the vicinity of a sleeve body of the speed change unit of FIG. 1. [Figure 4] 2 is an enlarged view showing the vicinity of a tapered portion and a contact portion of the speed change unit in FIG. 1. [Diagram 5] 13 is an enlarged view showing the vicinity of a tapered portion and an abutment portion of a speed change unit according to a modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, a speed change unit 10 (power transmission device) according to an embodiment of the present invention will be described with reference to the drawings.

[0029] The speed change unit 10 (power transmission) according to this embodiment is a unit that is mounted on a vehicle and changes the speed of power generated by an engine 2 as a driving source for traveling. The vehicle on which the speed change unit 10 illustrated in this embodiment is mounted is a part-time 4WD (four-wheel-drive) vehicle based on a front engine / rear drive (FR).

[0030] The engine 2 is, for example, a three-cylinder, four-stroke engine, and is mounted vertically with the crankshaft oriented vertically relative to the front-rear direction of the vehicle body. The number of cylinders of the engine 2 is not limited to three, but may be four or more, or two or less. The number of strokes of the engine 2 is also not limited to four, but may be two.

[0031] The transmission unit 10 (power transmission device) has a unit case 11, a torque converter 12, a CVT 20 (Continuously Variable Transmission), and a transfer 60. The transmission unit 10 is also provided with a forward clutch 93 and a reverse clutch 94.

[0032] The transmission unit 10 is configured by accommodating a torque converter 12, a CVT 20, and a transfer 60 in a unit case 11 that serves as a housing. The unit case 11 includes a transmission case 11a that accommodates the torque converter 12 and the CVT 20, and a transfer case 11b that accommodates the transfer 60.

[0033] <cvt> The CVT 20 is housed in a transmission case 11a. The CVT 20 includes an input shaft 21, a continuously variable transmission mechanism 30, an output shaft 23, and a reverse transmission mechanism 50. The transmission unit 10 is disposed vertically such that the input shaft 21 of the CVT 20 is oriented vertically and extends in the front-rear direction of the vehicle.

[0034] The input shaft 21 is formed as a hollow shaft, and is disposed so that its axis coincides with the rotation axis of the torque converter 12. In addition, an input shaft gear 22 is formed integrally with the input shaft 21. A front end Fr of the input shaft 21 is inserted into the torque converter 12.

[0035] In the following description, the direction in which the axis of the input shaft 21 extends may be simply referred to as "axial direction X".

[0036] In addition, in the following description, in the input direction (axial direction X) from the engine 2 that serves as the power source, the front side (front) as viewed from the power source (engine) may be simply referred to as the "front Fr" and the rear side (rear) may be simply referred to as the "rear Rr".

[0037] The output shaft 23 is disposed rearwardly Rr from the input shaft 21 with a gap therebetween. The output shaft 23 is disposed so that its axis is aligned with the axis of the input shaft 21. In other words, the input shaft 21 and the output shaft 23 are disposed so as to have a common axis extending vertically along the front-rear direction of the vehicle with a gap therebetween in the axial direction X. An output shaft gear 24 is integrally formed with the output shaft 23. The output shaft gear 24 meshes with a secondary output gear 35, which will be described later. The output shaft 23 is also provided with an abutment portion 23a (see FIG. 3). The abutment portion 23a will be described in detail later.

[0038] The output shaft gear 24 is a helical gear. Therefore, when the output shaft gear 24 receives rotational power from the secondary output gear 35 and rotates, a force (thrust force) toward the rear Rr along the axial direction X acts on the output shaft 23.

[0039] The continuously variable transmission mechanism 30 includes a primary shaft 31, a secondary shaft 33, a primary pulley 36, a secondary pulley 39, and a belt 42.

[0040] The primary shaft 31 is disposed so that its axis is along (parallel to) the axis of the input shaft 21. The primary shaft 31 is also provided at a position spaced apart from the input shaft 21 in the radial direction. A primary input gear 32 is attached to the primary shaft 31 so as to be capable of relative rotation. The primary input gear 32 meshes with the input shaft gear 22.

[0041] The secondary shaft 33 is disposed such that its axis is along (parallel to) the axis of the input shaft 21. The secondary shaft 33 is also provided at a position radially spaced from the axis of the input shaft 21. A secondary input gear 34 and a secondary output gear 35 are attached to the secondary shaft 33.

[0042] The secondary input gear 34 is provided on the front Fr side of the secondary shaft 33 and is rotatable relative to the secondary shaft 33.

[0043] The secondary output gear 35 is provided on the rear Rr side of the secondary shaft 33. The secondary output gear 35 is attached so as to be unable to rotate relative to the secondary shaft 33. The secondary output gear 35 meshes with the output shaft gear 24 provided on the output shaft 23.

[0044] The primary pulley 36 includes a primary fixed sheave 36a and a primary movable sheave 36b. The primary fixed sheave 36a is fixed to the primary shaft 31. The primary movable sheave 36b is disposed to face the primary fixed sheave 36a with a belt 42 sandwiched therebetween, and is supported so as to be movable in the axial direction of the primary shaft 31 but not rotatable relative thereto. A cylinder 37 is provided in front Fr of the primary movable sheave 36b. A hydraulic chamber (piston chamber) 38 is formed between the primary movable sheave 36b and the cylinder 37.

[0045] The secondary pulley 39 includes a secondary fixed sheave 39a and a secondary movable sheave 39b. The secondary fixed sheave 39a is fixed to the secondary shaft 33. The secondary movable sheave 39b is disposed to face the secondary fixed sheave 39a with a belt 42 sandwiched therebetween, and is supported so as to be movable in the axial direction of the secondary shaft 33 but not rotatable relative thereto. A piston 40 is provided behind the secondary movable sheave 39b. A hydraulic chamber 41 is formed between the secondary movable sheave 39b and the piston 40.

[0046] The belt 42 is formed in an endless shape. The belt 42 is wound around the primary pulley 36 and the secondary pulley 39. To explain in more detail, on the primary pulley 36 side, the belt 42 is wound around the primary pulley 36 while being sandwiched between the primary fixed sheave 36a and the primary movable sheave 36b. On the secondary pulley 39 side, the belt 42 is wound around the secondary pulley 39 while being sandwiched between the secondary fixed sheave 39a and the secondary movable sheave 39b.

[0047] In the continuously variable transmission mechanism 30, the oil pressure supplied to each hydraulic chamber 38, 41 of the primary pulley 36 and the secondary pulley 39 is controlled to change the groove width of each of the primary pulley 36 and the secondary pulley 39, thereby continuously and steplessly changing the belt speed ratio (pulley ratio between the primary pulley 36 and the secondary pulley 39) within a certain speed ratio range.

[0048] The reverse transmission mechanism 50 is a mechanism that transmits the power (rotation) of the input shaft 21 to the secondary input gear 34. The reverse transmission mechanism 50 includes a reverse idler shaft 51, a first reverse gear 52, and a second reverse gear 53. The first reverse gear 52 is formed integrally with the reverse idler shaft 51, and meshes with the input shaft gear 22. The second reverse gear 53 is formed integrally with the reverse idler shaft 51 at a rear side Rr of the first reverse gear 52, and meshes with the secondary input gear 34.

[0049] <Transfer> The transfer 60 is a mechanism that transmits the power (rotation) of the output shaft 23 to the front wheels of the vehicle. The transfer 60 includes a transmission shaft 61, a first sprocket 62, a second sprocket 63, a chain 64, and a transfer clutch 70 (clutch device).

[0050] 2, the transmission unit 10 is provided with a sleeve body 90, and the transfer clutch 70 (clutch drum 71) is attached to the output shaft 23 via the sleeve body 90. Also, a clutch hub 72 of the transmission unit 10 is formed with a support portion 91, and the clutch hub 72 of the transfer clutch 70 has the support portion 91 attached to the first sprocket 62.

[0051] The sleeve body 90 (connecting member) is a member that connects the transfer clutch 70 to the output shaft 23. The sleeve body 90 is a cylindrical member with a substantially circular cross-sectional shape, and serves as a sleeve member through which the output shaft 23 can be inserted. As shown in Fig. 2, the sleeve body 90 is disposed between the output shaft gear 24 and the first sprocket 62. In addition, the sleeve body 90 has a spline formed on its inner circumferential surface on the rear Rr side, and is attached to the outer circumferential surface of the output shaft 23 by spline fitting.

[0052] 3, the sleeve body 90 is provided with a connecting portion 90a and a tapered portion 90b. The connecting portion 90a is formed in a flange shape so as to protrude outward from the outer circumferential surface of the sleeve body 90, and is formed in a position that is central in the axial direction of the sleeve body 90 and faces the rear end portion of the secondary shaft 33 in the axial radial direction. The shape and function of the tapered portion 90b will be described in detail later.

[0053] The support portion 91 is formed on the clutch hub 72. As shown in Fig. 3, the support portion 91 is disposed between the first sprocket 62 and the sleeve body 90. The support portion 91 integrally includes a substantially cylindrical outer fitting portion 91a that surrounds the output shaft 23, and a flange-like portion 91b that is formed in a flange shape so as to extend radially from a front end portion of the outer fitting portion 91a.

[0054] The outer circumferential surface of the outer fitting portion 91a is formed with splines, and the outer circumferential surface is fitted with splines formed on the inner circumferential surface of the extension portion 62a of the first sprocket 62 (see FIG. 3). In other words, the outer fitting portion 91a and the extension portion 62a of the first sprocket 62 are connected by spline fitting so as to be unable to rotate relative to each other. On the other hand, the inner circumferential surface of the outer fitting portion 91a is not in close contact with the circumferential surface of the output shaft 23, and a small gap is formed between the outer circumferential surface of the output shaft 23 and the inner circumferential surface of the outer fitting portion 91a (see FIG. 3). Therefore, the outer fitting portion 91a is rotatable relative to the output shaft 23.

[0055] In this way, the support portion 91 is unable to rotate relative to the first sprocket 62, but is able to rotate relative to the output shaft 23. A thrust bearing 92 is provided between the sleeve body 90 and the support portion 91 to reduce mechanical loss during the relative rotation therebetween.

[0056] As shown in FIG. 1, the transmission shaft 61 is disposed in parallel to the output shaft 23 at a position spaced apart from the output shaft 23 in the radial direction. The first sprocket 62 is rotatably supported by the transfer case 11b and is rotatable relative to the output shaft 23. As shown in FIG. 2, the first sprocket 62 is provided with an extension 62a formed to extend forward Fr. The second sprocket 63 is formed integrally with the transmission shaft 61 in a substantially annular plate shape that protrudes from the transmission shaft 61 in the axial radial direction. The second sprocket 63 has a plurality of teeth formed at equal intervals on its outer periphery in the circumferential direction. The chain 64 is formed endlessly and is wound around the first sprocket 62 and the second sprocket 63.

[0057] The transfer clutch 70 (clutch device) is provided to switch between permitting and restricting power transmission to the rear wheels of the vehicle. The transfer clutch 70 is provided in front Fr of the first sprocket 62. As shown in FIG. 2, the transfer clutch 70 includes a clutch drum 71, a clutch hub 72, a clutch piston 73, and a canceller 74.

[0058] 3, the inner peripheral end of the clutch drum 71 is connected (fixed) to a connection portion 90a (sleeve body 90) so as to be immovable relative to the connection portion 90a. A plurality of clutch discs 75 are held on the inner peripheral surface of the cylindrical portion of the clutch drum 71 and arranged at intervals in the axial direction.

[0059] A plurality of clutch plates 76 are arranged and held at intervals in the axial direction on the outer circumferential surface of the cylindrical portion of clutch hub 72. The clutch discs 75 and the clutch plates 76 are arranged alternately in the axial direction. As described above, the clutch hub 72 is formed with a support portion 91.

[0060] Clutch piston 73 is provided between clutch drum 71 and clutch hub 72 so as to be movable in the axial direction. As shown in Fig. 2, clutch piston 73 extends from sleeve body 90 toward clutch disc 75 while repeatedly bending. A seal member 78 is provided in the middle of clutch piston 73. Seal member 78 abuts liquid-tightly against clutch drum 71 regardless of the position of clutch piston 73. As a result, a hydraulic chamber 77 is formed between clutch drum 71 and clutch piston 73, to which hydraulic pressure acting on clutch piston 73 is supplied.

[0061] The canceller 74 is provided between the clutch hub 72 and the clutch piston 73. The canceller 74 is formed in a substantially annular plate shape. The inner peripheral end of the canceller 74 is fixed to a sleeve body 90. A seal member 79 is provided on the outer peripheral end of the canceller 74. The seal member 79 abuts against the clutch piston 73 regardless of the position of the clutch piston 73. A return spring 80 is provided between the clutch piston 73 and the canceller 74. The biasing force (elastic force) of the return spring 80 elastically biases the clutch piston 73 and the canceller 74 in directions away from each other.

[0062] The clutch piston 73 moves toward the clutch disc 75 by the hydraulic pressure supplied to the hydraulic chamber 77, and presses the clutch disc 75. This pressure brings the clutch disc 75 and the clutch plate 76 into pressure contact, and the transfer clutch 70 is engaged. The engagement of the transfer clutch 70 prevents the clutch drum 71 and the clutch hub 72 from rotating relative to each other, and the support portion 91, the output shaft 23, and the sleeve body 90 rotate integrally, and the first sprocket 62 rotates integrally with the rotation of the support portion 91. The rotation (power) of the first sprocket 62 is transmitted to the second sprocket 63 via the chain 64, causing the second sprocket 63 to rotate in the same direction as the first sprocket 62. The transmission shaft 61 then rotates integrally with the second sprocket 63.

[0063] When the hydraulic pressure in the hydraulic chamber 77 is released from the engaged state of the transfer clutch 70, the biasing force of the return spring 80 moves the clutch piston 73 in a direction away from the canceller 74, and the clutch piston 73 releases the pressure on the clutch disc 75. As a result, the pressure contact between the clutch disc 75 and the clutch plate 76 is released, and the transfer clutch 70 is released. The release of the transfer clutch 70 allows the relative rotation between the clutch drum 71 and the clutch hub 72. Therefore, even if the output shaft 23 and the sleeve body 90 rotate, the rotation is not transmitted to the support portion 91 and the first sprocket 62, and therefore is not transmitted from the first sprocket 62 to the transmission shaft 61 via the chain 64 and the second sprocket 63.

[0064] The forward clutch 93 is provided to permit / prohibit rotation of the primary input gear 32 relative to the primary shaft 31. The forward clutch 93 is a clutch device including a clutch drum, a clutch hub, a clutch piston, etc., and a hydraulic chamber is formed between the clutch drum and the clutch piston. In addition, the clutch piston is elastically biased rearward Rr by a return spring.

[0065] When the clutch piston moves forward Fr due to the hydraulic pressure supplied to the hydraulic chamber and presses the clutch plate from the rear Rr, the clutch plate and the clutch disc are pressed together, engaging the forward clutch 93. On the other hand, when the hydraulic pressure is released from the engaged state of the forward clutch 93, the clutch piston moves backward Rr due to the biasing force of the return spring, the pressure contact between the clutch disc and the clutch plate is released, and the forward clutch 93 is disengaged.

[0066] When the forward clutch 93 is engaged (engaged state), relative rotation of the primary input gear 32 with respect to the primary shaft 31 is prohibited. In other words, due to the engagement of the forward clutch 93, the primary shaft 31 and the primary input gear 32 rotate integrally. On the other hand, when the forward clutch 93 is released (disengaged state), relative rotation of the primary input gear 32 with respect to the primary shaft 31 is permitted. Therefore, even if the primary input gear 32 rotates, the rotation is not transmitted to the primary shaft 31.

[0067] The reverse clutch 94 is provided to permit / prohibit rotation of the secondary input gear 34 relative to the secondary shaft 33. The reverse clutch 94 is a clutch device including a clutch drum, a clutch hub, and a clutch piston. The clutch piston of the reverse clutch 94 is in liquid-tight contact with the clutch drum, and a hydraulic chamber is formed between the clutch drum and the clutch piston to which hydraulic pressure acting on the clutch piston is supplied. In addition, the clutch piston is elastically biased rearward Rr by a return spring.

[0068] When the hydraulic pressure supplied to the hydraulic chamber moves the clutch piston forward Fr and presses the clutch plate from the rear Rr, the clutch plate and the clutch disc come into pressure contact, engaging the reverse clutch 94. On the other hand, when the hydraulic pressure is released from the engaged state of the reverse clutch 94, the clutch piston moves backward Rr due to the biasing force of the return spring, the pressure contact between the clutch disc and the clutch plate is released, and the reverse clutch 94 is disengaged.

[0069] When the reverse clutch 94 is engaged (engaged state), relative rotation of the secondary input gear 34 with respect to the secondary shaft 33 is prohibited. In other words, due to the engagement of the reverse clutch 94, the secondary shaft 33 and the secondary input gear 34 rotate integrally. On the other hand, when the reverse clutch 94 is released (disengaged state), relative rotation of the secondary input gear 34 with respect to the secondary shaft 33 is permitted. Therefore, even if the secondary input gear 34 rotates, the rotation is not transmitted to the secondary shaft 33.

[0070] <Power transmission path> Next, the power transmission path in each driving state of the vehicle will be described. A vehicle equipped with the transmission unit 10 can switch between a two-wheel drive state (2WD state) using the left and right rear wheels and a four-wheel drive state (4WD state) using the left and right front wheels and rear wheels. The power transmission path in each state of forward travel, reverse travel, two-wheel drive state (2WD state), and four-wheel drive state (4WD state) will be described below.

[0071] When the vehicle moves forward, the forward clutch 93 is engaged and the reverse clutch 94 is disengaged. The power input from the engine 2 via the torque converter 12 to the input shaft 21 is transmitted from the input shaft gear 22 via the primary input gear 32 to the primary shaft 31 due to the engagement of the forward clutch 93. On the other hand, even if the power input to the input shaft 21 is transmitted from the input shaft gear 22 to the secondary input gear 34 and the secondary input gear 34 rotates, the secondary input gear 34 rotates freely relative to the secondary shaft 33 (secondary shaft 33) due to the disengagement of the reverse clutch 94, and no power is transmitted to the secondary shaft 33.

[0072] The power transmitted to the primary shaft 31 is changed in speed at a belt speed ratio corresponding to the pulley ratio between the primary pulley 36 and the secondary pulley 39, and then transmitted to the secondary shaft 33. The power transmitted to the secondary shaft 33 is then transmitted from the secondary output gear 35 to the output shaft 23 via the output shaft gear 24.

[0073] When the vehicle moves backward, the forward clutch 93 is released and the reverse clutch 94 is engaged. Power input from the engine 2 via the torque converter 12 to the input shaft 21 is transmitted from the input shaft gear 22 via the reverse transmission mechanism 50 and the secondary input gear 34 to the secondary shaft 33 due to engagement of the reverse clutch 94. At this time, the secondary shaft 33 rotates in the direction opposite to that when the vehicle moves forward. The power transmitted to the secondary shaft 33 is transmitted from the secondary output gear 35 to the output shaft 23 via the output shaft gear 24.

[0074] On the other hand, even if the power input to the input shaft 21 is transmitted from the input shaft gear 22 to the primary input gear 32 and the primary input gear 32 rotates, the release of the forward clutch 93 causes the primary input gear 32 to rotate freely relative to the primary shaft 31, and no power is transmitted to the primary shaft 31.

[0075] When the transfer clutch 70 is released, the power transmission to the front wheels is cut off and the vehicle enters a two-wheel drive state in which the vehicle runs on the rear wheels. As described above, when the transfer clutch 70 is released (two-wheel drive state), the power (rotation) of the output shaft 23 is not transmitted to the first sprocket 62 and is therefore not transmitted to the transmission shaft 61. Meanwhile, the power of the output shaft 23 is transmitted to the propeller shaft, and from the propeller shaft, it is transmitted to the left and right rear wheels via the rear differential gear and the drive shaft. As a result, the left and right rear wheels become drive wheels and the vehicle runs in two-wheel drive state.

[0076] On the other hand, when the transfer clutch 70 is engaged, power is transmitted to the front wheels, resulting in a four-wheel drive state in which the vehicle travels on the front and rear wheels. As described above, when the transfer clutch 70 is engaged (four-wheel drive state), the power of the output shaft 23 is transmitted to the first sprocket 62, and the rotation (power) of the first sprocket 62 is transmitted to the second sprocket 63 via the chain 64. This causes the second sprocket 63 to rotate in the same direction as the first sprocket 62, and the transmission shaft 61 to rotate integrally with the second sprocket 63. The rotation of the transmission shaft 61 is transmitted to the left and right front wheels via the front differential gear and the drive shaft.

[0077] On the other hand, the power of the output shaft 23 is transmitted to the propeller shaft, and then from the propeller shaft to the left and right rear wheels via the rear differential gear and the drive shaft. As a result, the left and right front wheels and the rear wheels all become drive wheels, and the vehicle runs in a four-wheel drive state.

[0078] <Connection structure between output shaft and transfer clutch> Next, the connection structure between the output shaft 23 and the transfer clutch 70 will be described in detail. In the following description of the tapered portion 90b and the abutting portion 23a, the axis of the output shaft 23 or the sleeve body 90 is taken as a reference line L, and the gradients with respect to the reference line L may be simply described as "inclination angles θ1, θ2" (see FIG. 4). In the following description, the portion that is spline-fitted with the sleeve body 90 may be simply described as "spline-fitting portion B."

[0079] As described above, in the speed change unit 10 (power transmission device), the output shaft gear 24 provided midway in the axial direction of the output shaft 23 is configured as a helical gear. The output shaft 23 has a contact portion 23a. The output shaft 23 is supported by a bearing 25. The sleeve body 90 is provided with a tapered portion 90b (see FIG. 3).

[0080] As shown in Fig. 3, the contact portion 23a is formed near the output shaft gear 24 of the output shaft 23 and on one side of the output shaft gear 24 in the axial direction of the output shaft 23 (the rear Rr side in this embodiment). The contact portion 23a is a part of the outer circumferential surface of the output shaft 23 formed in a tapered shape, and is a part that contacts the tapered portion 90b. As shown in Fig. 4, the contact portion 23a is a tapered part that has a downward gradient from the front Fr to the rear Rr (the radial size decreases from the front Fr to the rear Rr), and has a predetermined inclination angle θ2.

[0081] As shown in Fig. 3, the tapered portion 90b is formed on the inner peripheral surface of the sleeve body 90, and a part of the inner peripheral surface of the sleeve body 90 is formed in a tapered shape. More specifically, the tapered portion 90b is formed on the inner peripheral surface near the opening on the front Fr side. As shown in Fig. 4, the tapered portion 90b is a tapered portion that has a downward gradient from the front Fr to the rear Rr (the radial size decreases from the front Fr to the rear Rr), and has a predetermined inclination angle θ1.

[0082] As shown in Fig. 4, the inclination angle θ1 of the tapered portion 90b is slightly smaller than the inclination angle θ2 of the abutting portion 23a. To explain in more detail, the inclination angle θ1 of the tapered portion 90b is smaller than the inclination angle θ2 of the abutting portion 23a by a difference of about the tolerance. In other words, the tapered portion 90b has a slightly gentler inclination than the abutting portion 23a.

[0083] In this manner, the speed change unit 10 has the sleeve body 90 that connects the transfer clutch 70 to the output shaft 23, and the sleeve body 90 is attached to the outer circumferential surface of the output shaft 23 by spline fitting. Also, a tapered portion 90b is formed on the inner circumferential surface of the sleeve body 90.

[0084] The bearing 25 is a thrust bearing for supporting the output shaft 23. The bearing 25 is provided on the other side (the front Fr side in this embodiment) of the output shaft gear 24 in the axial direction of the output shaft 23 with respect to the contact portion 23a described above.

[0085] A biasing member 27 is provided between the bearing 25 and the output shaft gear 24 via a washer 29. The biasing member 27 may be, for example, a compression spring, but in this embodiment, a wave spring is used. The biasing member 27 uses the bearing 25 as a seat and is capable of applying a biasing force to the output shaft gear 24 in a direction toward one axial side of the output shaft 23. This allows a pressing force to be applied to the sleeve body 90 from a contact portion 23a provided on one axial side (rear Rr side) via the output shaft gear 24.

[0086] Furthermore, the sleeve body 90 is provided with a tapered portion 90b. Therefore, when the contact portion 23a is pressed against the sleeve body 90 by the biasing force of the biasing member 27, the tapered portion 90b and the contact portion 23a are in surface contact. In this state, the sleeve body 90 is restricted from moving in the circumferential direction relative to the output shaft 23 (stopping of rotation due to surface contact). The sleeve body 90 is connected to the output shaft 23 by spline fitting near the end of the rear Rr, and the rotation of the sleeve body 90 is restricted by contact between the tapered portion 90b and the contact portion 23a near the end of the front Fr. That is, the sleeve body 90 is pressed in the thrust direction A1 and engaged with the output shaft 23 at two points (the tapered portion 90b and the spline fitting portion B) in the longitudinal direction (axial direction X), and is rotatable integrally with the output shaft 23.

[0087] The above-mentioned effect of preventing the sleeve body 90 from rotating due to the biasing force of the biasing member 27 is particularly effective when the secondary output gear 35 rotates at a low speed and the input torque is small. On the other hand, when the rotation speed of the secondary output gear 35 increases and the input torque increases, the effect of preventing the sleeve body 90 from rotating is obtained due to the force acting on the output shaft 23 under the influence of the input torque. Specifically, when the secondary output gear 35 rotates, the torque of the secondary output gear 35 is transmitted to the output shaft gear 24. At this time, since the output shaft gear 24 is a helical gear, a force in the thrust direction (rearward Rr of the axial direction X) acts on the output shaft 23. In other words, the output shaft 23 is pushed in the thrust direction A1 (see the arrow A1 in FIG. 3). As a result, the output shaft 23 is slightly displaced so as to push the sleeve body 90 toward the rear Rr side. At this time, the opening side (front Fr side) of the tapered portion 90b is pushed by the contact portion 23a and slightly deformed so as to expand.

[0088] The sleeve body 90 is affected by the input torque transmitted from the secondary output gear 35 to the output shaft gear 24, and the tapered portion 90b and the abutment portion 23a come into surface contact with each other, so that the sleeve body 90 is in a state in which its movement in the circumferential direction with respect to the output shaft 23 is restricted (a state in which the sleeve body 90 is prevented from rotating by surface contact). As described above, the sleeve body 90 is connected to the output shaft 23 by spline fitting near the end portion of the rear Rr, and its rotation is restricted by contact between the tapered portion 90b and the abutment portion 23a near the end portion of the front Fr. That is, the sleeve body 90 is pressed in the thrust direction A1 and engaged with the output shaft 23 at two points (the tapered portion 90b and the spline fitting portion B) in the longitudinal direction (axial direction X), so that the sleeve body 90 can rotate integrally with the output shaft 23.

[0089] With the above-mentioned configuration, the transmission unit 10 can connect (fix) the output shaft 23 and the sleeve body 90 by generating frictional force at a portion other than the portion connected by the spline (splined engagement portion), thereby suppressing the rattle of the spline. That is, when the secondary output gear 35 rotates at a low speed and the input torque is small, the output shaft 23 and the sleeve body 90 are connected not only at the splined engagement portion but also at the portion where the tapered portion 90b is provided under the influence of the biasing force of the biasing member 27. When the rotation speed of the secondary output gear 35 increases and the input torque increases, the output shaft 23 and the sleeve body 90 are connected not only at the splined engagement portion but also at the portion where the tapered portion 90b is provided under the influence of the force acting on the output shaft 23 under the influence of the input torque. Therefore, the transmission unit 10 can restrict the movement of the backlash between the output shaft 23 and the sleeve body 90 in either a state where the secondary output gear 35 rotates at a low speed or a state where the rotation speed is increased. In other words, the contact portion between the tapered portion 90b and the contact portion 23a functions as a rotation stopper, thereby reducing noise caused by the spline teeth striking between the two components.

[0090] The speed change unit 10 uses a wave spring as the biasing member 27. Therefore, the speed change unit 10 is compact in the axial direction of the shaft and can generate a sufficient biasing force, compared to a case in which a compression spring or the like is used as the biasing member.

[0091] Furthermore, the transmission unit 10 can apply a frictional force proportional to the input torque to the output shaft 23. More specifically, a frictional force is generated between the sleeve body 90 and the output shaft 23 due to the thrust force that the helical gear (output shaft gear 24) receives when rotating. In other words, when the torque is large, a large frictional force can be applied. Therefore, even if the torque on the input side increases, a frictional force corresponding to the input torque is generated, so that even if torque fluctuations occur, both parts (output shaft 23 and sleeve body 90) can be firmly connected (fixed) without slipping.

[0092] Furthermore, the transmission unit 10 can have a simpler structure than a structure in which the output shaft 23 and the sleeve body 90 are fixed together by a member such as a lock nut. Also, the overall length can be shortened compared to a case in which the output shaft 23 and the sleeve body 90 are connected together by a lock nut or the like. As a result, this can contribute to weight reduction and cost reduction.

[0093] Here, if the inclination angle θ1 of the tapered portion 90b and the inclination angle θ2 of the abutting portion 23a are formed to completely match, a high frictional force can be generated between the surface of the tapered portion 90b and the surface of the abutting portion 23a. However, since there is a tolerance when forming a tapered shape in a part, it is difficult to completely match the taper angles of the two parts.

[0094] In contrast, in the transmission unit 10, the inclination angle θ1 of the tapered portion 90b is smaller than the inclination angle θ2 of the abutment portion 23a (see FIG. 4). In other words, the tapered portion 90b is slightly more gently inclined than the abutment portion 23a. Therefore, even if the tapered portion 90b and the abutment portion 23a have a tolerance, the large diameter side (the opening side of the sleeve body 90) of the tapered portion 90b comes into contact with the abutment portion 23a first, opening the opening diameter, and the tapered portion 90b and the abutment portion 23a can come into surface contact with each other. In other words, the abutment portion 23a and the tapered portion 90b are configured to come into contact with each other more strongly toward the helical gear (output shaft gear 24) side (the inlet side of the sleeve body 90 has strong interference). In this way, in the transmission unit 10, when a thrust load is input, the opening of the sleeve body 90 opens slightly, and approximately the entire surface of the tapered portion 90b comes into surface contact with the abutment portion 23a.

[0095] In this way, in the transmission unit 10, when a force in the thrust direction acts on the output shaft 23, the inlet side of the tapered portion 90b comes into contact with the abutment portion 23a first. This generates a high frictional force between the tapered portion 90b and the abutment portion 23a, preventing the sleeve body 90 from slipping relative to the output shaft 23.

[0096] Furthermore, in the speed change unit 10 of this embodiment, the sleeve body 90 is a sleeve member through which the output shaft 23 can be inserted.

[0097] This allows the transfer clutch 70 to be connected to the output shaft 23 with a simple structure. Also, the tapered portion 90b and the splines can be easily formed.

[0098] As described above, in the transfer clutch 70, the clutch drum 71 is connected (fixed) to the output shaft 23 via the sleeve body 90. Meanwhile, in the transfer clutch 70, the clutch hub 72 is connected to the first sprocket 62. In addition, the outer fitting portion 91a (support portion 91) of the clutch hub 72 and the extension portion 62a (first sprocket 62) are joined by spline fitting so as to be non-rotatable relative to each other.

[0099] In this way, the transfer clutch 70 is configured so that the clutch drum 71 and the like rotate integrally with the output shaft 23, and the clutch hub 72 and the like are configured to be rotatable relative to the output shaft 23. Therefore, when the transfer clutch 70 is in a disengaged state, the output shaft 23 and the sleeve body 90 are in a state in which power transmission is cut off (a free state) with respect to the first sprocket 62 and the clutch hub 72. In other words, in the two-wheel drive state, the output shaft 23 and the sleeve body 90 are free from the clutch hub 72 and the first sprocket 62 of the transfer clutch 70.

[0100] Therefore, in the two-wheel drive state, the sleeve body 90 is easy to move, and abnormal noise is likely to occur. To explain in more detail, when the output shaft 23, the sleeve body 90, the transfer clutch 70, and the first sprocket 62 rotate integrally, as in the four-wheel drive state, these members are in a state in which it is difficult for them to move relative to each other. Therefore, in the four-wheel drive state, a reaction force acts between the members that rotate integrally, and abnormal noise is unlikely to occur. In contrast, in the two-wheel drive state, although the sleeve body 90 also rotates with the rotation of the output shaft 23, the sleeve body 90 can move freely relative to the output shaft 23 by the amount of the spline gap, and therefore abnormal noise is likely to occur.

[0101] In contrast, in the change gear unit 10 of this embodiment, as described above, a frictional force is generated in the portion (tapered portion 90b) other than the portion connected by the spline (spline fitting portion B) to connect (fix) the output shaft 23 and the sleeve body 90, thereby suppressing backlash of the spline. Therefore, if a locking structure using the sleeve body 90 is provided as the mounting structure for the clutch device that switches between engagement and release, the generation of abnormal noise can be suitably suppressed.

[0102] Although the speed change unit 10 (power transmission device) according to the embodiment of the present invention has been described above, the present invention is not limited to this embodiment.

[0103] For example, the transmission unit 10 according to the above embodiment is shown as an example having a continuously variable transmission mechanism (CVT) capable of continuously changing the gear ratio, but the power transmission device of the present invention is not limited to the above embodiment. Specifically, the power transmission device of the present invention may be a device that changes gears by switching gears (a normal transmission). In addition, the gear switching may be performed automatically (AT: automatic transmission) or manually (MT: manual transmission).

[0104] In addition, in the gear change unit 10 according to the embodiment described above, an example has been shown in which the inclination angle θ1 of the tapered portion 90b is smaller than the inclination angle θ2 of the abutment portion 23a (inclination angle θ1<inclination angle θ2), but the present invention is not limited to the above embodiment. Specifically, the power transmission device of the present invention may be configured so that the inclination angle of the tapered portion and the inclination angle of the abutment portion match (inclination angle θ1=inclination angle θ2), or the inclination angle of the tapered portion may be larger than the inclination angle of the abutment portion (inclination angle θ1>inclination angle θ2).

[0105] In addition, in the transmission unit 10 according to the embodiment described above, an example has been shown in which the sleeve body 90 having the tapered portion 90b is provided as a member connecting the output shaft 23 and the transfer clutch 70, but the present invention is not limited to the embodiment described above. Specifically, the part connected via the sleeve member having the tapered portion may be a shaft body other than the output shaft (e.g., an input shaft, a primary shaft, a secondary shaft, etc.), or may be a clutch device other than a transfer clutch (e.g., a forward clutch, a reverse clutch, etc.).

[0106] In addition, in the above-described embodiment, the transmission unit 10 mounted on an FR-based 4WD vehicle was taken up as an example of the power transmission device of the present invention, but the power transmission device of the present invention may be applied to a power transmission device mounted on an FF (front engine, front drive) based part-time 4WD vehicle, or a RR (rear engine, rear drive) based part-time 4WD vehicle.

[0107] In the above embodiment, the output shaft 23 is biased toward one side in the axial direction by the biasing member 27 provided on the other side (left side in the figure) of the output shaft gear 24, so that a pressing force acts from the abutting portion 23a provided on the output shaft 23 against the tapered portion 90b provided on the sleeve body 90, but the present invention is not limited to this. For example, instead of providing the biasing member 27 as exemplified in the above embodiment, as shown in Fig. 5, a biasing member 127 may be provided on the sleeve body 90 on the opposite side (right side in the figure) to the side where the tapered portion 90b is provided, and the sleeve body 90 may be biased from the other side (right side in the figure) in the axial direction toward one side (right side in the figure) by the biasing force of the biasing member 127.

[0108] More specifically, as described above, the support portion 91 of the clutch hub 72 constituting the transmission unit 10 is disposed at a position opposite to the tapered portion 90b in the axial direction (the right side in the figure) of the sleeve body 90. A thrust bearing 92 is provided between the sleeve body 90 and the support portion 91. A first sprocket 62 constituting the transfer 60 is provided at a position adjacent to the support portion 91 in the axial direction. In the modified example shown in FIG. 5, a biasing member 127 is disposed between the support portion 91 and the first sprocket 62. The biasing member 127 is formed of a compression spring and is capable of expanding and contracting along the outer circumferential surface of the output shaft 23. As a result, the biasing member 127 is capable of indirectly applying a biasing force to the sleeve body 90 from the other side (the right side in the figure) in the axial direction toward one side (the right side in the figure) via the thrust bearing 92.

[0109] 5 is configured as described above, the biasing force of the biasing member 127 causes the abutment portion 23a and the sleeve body 90 to come into contact with each other while applying a pressing force between them. This allows the change gear unit 10 according to this modification to restrict movement due to backlash between the output shaft 23 and the sleeve body 90. Therefore, the change gear unit 10 according to this modification can effectively suppress the generation of noise due to spline tooth strike, even in a situation where the thrust force acting on the output shaft gear 24 (helical gear) provided on the output shaft 23 is small.

[0110] In addition, in the change gear unit 10 shown in FIG. 5, the biasing member 127 is configured by a compression spring that expands and contracts along the outer circumferential surface of the output shaft 23. This allows the compression spring constituting the biasing member 127 to be guided by the output shaft 23 and to reliably expand and contract along the axial direction, thereby reliably applying an appropriate amount of biasing force to the sleeve body 90. Therefore, in the change gear unit 10 shown in FIG. 5, the sleeve body 90 is firmly pressed against the abutment portion 23a by the biasing force applied by the biasing member 127. Therefore, the change gear unit 10 according to this modification can more reliably suppress the generation of noise due to spline tooth strike, even in a situation where the thrust force is small.

[0111] 5, instead of the biasing member 27 illustrated in the above embodiment, a configuration is illustrated in which a biasing member 127 is provided on the side of the sleeve body 90 opposite to where the tapered portion 90b is provided, but a configuration in which a biasing member 27 is also provided in addition to the biasing member 127 may also be used. Also, in addition to the biasing member 27 and the biasing member 127, a configuration in which another biasing member is further provided and the biasing member can apply a biasing force in a direction in which 23a and the sleeve body 90 approach each other in the axial direction may also be used.

[0112] In addition, in the modified example shown in FIG. 5, a configuration is adopted in which a biasing force from the biasing member 127 can be indirectly applied to the sleeve body 90 via the support portion 91 and the thrust bearing 92, but the present invention is not limited to this, and a configuration in which a biasing force from the biasing member 127 can be applied directly to the sleeve body 90 is also possible.

[0113] The present invention is not limited to the above-described embodiment, and other embodiments may be made within the scope of the claims, based on the teachings and spirit of the present invention. The components of the above-described embodiment may be arbitrarily selected and combined. In addition, any component of the embodiment may be arbitrarily combined with any component described in the Summary for Solving the Problems or any component that embodies any component described in the Summary for Solving the Problems. [Industrial Applicability]

[0114] The present invention can be suitably employed as a power transmission device for use in a vehicle. [Explanation of symbols]

[0115] 10. Transmission unit (power transmission device) 23 Output shaft (shaft body) 23a Contact part 25 Bearings 27 Pressing member 24 Output shaft gear (helical gear) 70 Transfer clutch (clutch device) 90 Sleeve body (connection member, sleeve member) 90b Tapered section 127 Biasing member In the variant shown in FIG. A1 Thrust direction B spline fitting L reference line θ1 Tilt angle θ2 Tilt angle< / cvt>

Claims

1. A power transmission device having a shaft body provided with a helical gear and a clutch device attached to the shaft body, a connecting member for connecting the clutch device to the shaft body; One or more biasing members; having The connecting member is attached to the outer circumferential surface of the shaft by spline fitting, the shaft body has an abutment portion that abuts against the connection member from one side in an axial direction of the helical gear, a biasing member that directly or indirectly applies a biasing force to either the connecting member or the shaft body or both in a direction in which the abutment portion and the connecting member approach each other in the axial direction.

2. The connecting member abuts against the abutment portion on one side in the axial direction, 2. The power transmission device according to claim 1, wherein a part or all of the biasing members apply a biasing force to the connecting member on the other side in the axial direction in a direction toward one side in the axial direction.

3. The contact portion is formed in a tapered shape, 3. The power transmission device according to claim 1, wherein the connecting member has an inner circumferential surface that is formed with a tapered portion at a portion where the connecting member abuts against the abutting portion.

Images