Coupling structure between power transmission shafts for vehicle

Abstract

To provide a connection structure between power transmission shafts for a vehicle capable of suppressing deflection at a fitting part of a shaft and securing assemblability and disassemblability without requiring an increase in the number of components and an increase in component accuracy.SOLUTION: In the spline-fitting (spline-fitted portion 54) between the C shaft 52 and the FD shaft 56, a trapezoidal convex 54a and a trapezoidal convex 54b1 are provided at the rear end in the insertion direction of the top surface 54a1 of the outer-diameter-side spline-tooth 54b and at the rear end in the insertion direction of the top surface 54a2 of the inner-diameter-side spline-tooth 54a, respectively, to reduce the gap at the time of fitting, or a trapezoidal convex 54a1 and a trapezoidal convex 54b are provided at the front end in the insertion direction of the top surface of the outer-diameter-side spline-tooth and at the front end in the insertion direction of the top surface of the inner-diameter-side spline-tooth, respectively, to reduce the gap at the time of fitting. 54b1 54a3 54b2 54b3. Thus, a clearance between both ends of the spline fitting part 54 is reduced, and deflection in the spline fitting part 54 between the C shaft 52 and the FD shaft 56 is suppressed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a connection structure between vehicle power transmission shafts in which outer diameter side spline teeth and inner diameter side spline teeth are fitted together. [Background technology]

[0002] A well-known coupling structure for vehicle power transmission shafts is one in which outer diameter spline teeth and inner diameter spline teeth are fitted together. A gap exists between the outer diameter spline teeth and the inner diameter spline teeth. This gap can cause the connecting shaft to bend at the fitting portion, potentially resulting in poor tooth contact between the outer diameter spline teeth and the inner diameter spline teeth. To address this issue, a technology has been disclosed in which a tolerance ring is interposed between the outer diameter spline teeth and the inner diameter spline teeth to absorb the gap. For example, Patent Document 1 discloses a spline shaft fitting structure that does just that. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-53384 Summary of the Invention [Problem to be solved by the invention]

[0004] However, measures using tolerance rings increase the number of parts, and are sometimes difficult to adopt due to constraints on mounting space, power transmission, cost, etc. On the other hand, increasing the precision of the spline teeth to reduce the gap also poses manufacturing and cost issues, and changing the spline fit to a press fit reduces the amount of deflection, but makes assembly and disassembly difficult, which is unacceptable.

[0005] The present invention has been made in light of the above circumstances, and its object is to provide a connecting structure between power transmission shafts for a vehicle that can suppress deflection at the fitting portion of the shafts and ensure ease of assembly and disassembly without requiring an increase in the number of parts or improvement in part precision. [Means for solving the problem]

[0006] The gist of the present invention is (a) a connection structure between vehicle power transmission shafts in which outer diameter side spline teeth and inner diameter side spline teeth are fitted together, and (b) a platform-shaped convex portion is provided at the rear end in the insertion direction of the top surfaces of the outer diameter side spline teeth and the rear end in the insertion direction of the top surfaces of the inner diameter side spline teeth, or at the front end in the insertion direction of the top surfaces of the outer diameter side spline teeth and the front end in the insertion direction of the top surfaces of the inner diameter side spline teeth, to reduce a gap during fitting. [Effects of the Invention]

[0007] According to the present invention, a platform-shaped convex portion that reduces a gap during engagement is provided at the rear end of the crest surfaces of the outer-diameter spline teeth in the insertion direction and the rear end of the crest surfaces of the inner-diameter spline teeth in the insertion direction, or at the leading end of the crest surfaces of the outer-diameter spline teeth in the insertion direction and the leading end of the crest surfaces of the inner-diameter spline teeth in the insertion direction. This reduces the gap at both ends of the engagement portion, thereby suppressing deflection of the shaft at the engagement portion. Furthermore, the convex portion can be formed during the finishing stage of the manufacturing process by reusing the crest surfaces of the outer-diameter spline teeth and the inner-diameter spline teeth, making production easier, allowing for a smaller gap to be set, and ensuring meshing strength with a space-saving shape. Therefore, deflection of the shaft at the engagement portion is suppressed and ease of assembly and disassembly is ensured without requiring an increase in parts or part precision. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied; [Figure 2] 1 is a diagram illustrating a connection structure between power transmission shafts for a vehicle to which the present invention is applied; [Figure 3]FIG. 10 is a diagram corresponding to FIG. 2 and illustrating another embodiment of the present invention. [Figure 4] FIG. 3 is a cross-sectional view corresponding to the cross-sectional view of FIG. 2, illustrating another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0010] FIG. 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied. The vertical upward direction on the plane of FIG. 1 indicates the forward direction of the vehicle 10. In FIG. 1, the vehicle 10 is equipped with an engine 12 that functions as a power source, a pair of drive wheels 14, and a power transmission unit 16. The engine 12 and power transmission unit 16 are connected via an input shaft 18, and the power transmission unit 16 and drive wheels 14 are connected via a pair of drive shafts 20. Note that, for example, an electric motor may be used as the power source in addition to or instead of the engine 12.

[0011] The engine 12 is, for example, a known internal combustion engine, and an electronic control device 80 (described later) controls a fuel injection device, an ignition device, and the like provided on the vehicle 10, thereby controlling the engine torque Te of the engine 12.

[0012] The power transmission unit 16 includes a clutch K1, a hydraulic control circuit 22, a bevel gear 24, a transmission 26, and a limited slip differential (hereinafter referred to as LS differential) 58. Power from the engine 12 is transmitted via an input shaft 18 to the clutch K1, bevel gear 24, transmission 26, and LS differential 58 in that order, and from the LS differential 58 to the drive wheels 14 via a drive shaft 20. The LS differential 58 is a differential device equipped with a differential limiting mechanism.

[0013] The clutch K1 is, for example, a hydraulic friction engagement device provided between the engine 12 and the transmission 26. The clutch K1 has its control state (engaged state, released state) switched by a K1 hydraulic pressure PRk1 supplied from a hydraulic control circuit 22.

[0014] The bevel gear 24 is connected to the clutch K1 and the lay shaft 28, which is the input shaft of the transmission 26, and transmits the power transmitted from the engine 12 via the clutch K1 from the rotation axis in the forward direction of the vehicle 10 to the lay shaft 28, which is the rotation axis in the vehicle width direction.

[0015] The transmission 26 is a so-called parallel two-shaft transmission in which one of a plurality of gear stages (also synonymous with speed ratio) GS with different gear ratios (also synonymous with gear stages) γ (= input rotation speed Ni / output rotation speed No) is formed. The input rotation speed Ni is the rotation speed of the lay shaft 28, and the output rotation speed No is the rotation speed of the counter shaft (hereinafter referred to as C shaft) 52, which is the output shaft of the transmission 26.

[0016] The transmission 26 includes a plurality of gear pairs 30 that are constantly meshed. The gear pairs 30 include, in order from the bevel gear 24 side (input side) in the direction of the rotation axis CL1, a reverse gear pair 30a, a second-speed gear pair 30b, a first-speed gear pair 30c, a fourth-speed gear pair 30d, a fifth-speed gear pair 30e, a sixth-speed gear pair 30f, and a third-speed gear pair 30g. The direction of the rotation axis CL1 is synonymous with the axial direction of the lay shaft 28.

[0017] The gear pair 30 includes a drive gear 32 (including 32a1, 32a2, 32b, 32c, 32d, 32e, 32f, and 32g) and a driven gear 34 (including 34a, 34b, 34c, 34d, 34e, 34f, and 34g) that is constantly meshed with the drive gear 32. The reverse gear pair 30a includes two drive gears 32a1 and 32a2 for reversing the drive direction. The drive gear 32 is arranged so as not to rotate relative to the lay shaft 28. The driven gear 34 is fixed to the C shaft 52 in the direction of the rotation axis CL2 so as to be rotatable relative to the C shaft 52. The direction of the rotation axis CL2 is synonymous with the axial direction of the C shaft 52.

[0018] The transmission 26 includes a switching mechanism 36 (including 36a, 36b, 36c, and 36d) disposed on the C-shaft 52. The first switching mechanism 36a is disposed adjacent to the reverse driven gear 34a in the direction of the rotation axis CL2. The second switching mechanism 36b is disposed adjacent to the second-speed driven gear 34b and the first-speed driven gear 34c. The third switching mechanism 36c is disposed adjacent to the fourth-speed driven gear 34d and the fifth-speed driven gear 34e. The fourth switching mechanism 36d is disposed adjacent to the sixth-speed driven gear 34f and the third-speed driven gear 34g.

[0019] The switching mechanism 36 switches the power transmission state of the gear pair 30 between a power transmission enabled state and a power transmission disabled state. The switching mechanism 36 is a disconnecting device that can switch between a connected state in which one of the adjacent drive gears 32 is connected to the C shaft 52 so that they rotate integrally, and a disconnected state in which the other drive gear 32 is disconnected from the C shaft 52 so that they rotate relative to each other.

[0020] For example, when the reverse driven gear 34a and the C shaft 52 are connected via the first switching mechanism 36a, the transmission 26 is switched to a power transmission enabled state via the reverse gear pair 30a, and a reverse gear Rev is formed in the transmission 26. The same applies to second gear 2nd, first gear 1st, fourth gear 4th, fifth gear 5th, sixth gear 6th, and third gear 3rd.

[0021] The switching mechanism 36 has switching meshing teeth 38 (including 38a, 38b, 38c, 38d, 38e, 38f, and 38g) formed at a position facing the driven gear 34 in the direction of the rotation axis CL2. The driven gear 34 has gear-side meshing teeth 40 (including 40a, 40b, 40c, 40d, 40e, 40f, and 40g) that can mesh with the switching meshing teeth 38 formed at a position facing the switching mechanism 36 in the direction of the rotation axis CL2.

[0022] The transmission 26 is a dog transmission having dog clutches 50 (including 50a, 50b, 50c, 50d, 50e, 50f, and 50g). The dog clutch 50 is a dog clutch that is configured with a switching mechanism 36 having switching meshing teeth 38, gear-side meshing teeth 40, and the like. The switching meshing teeth 38 and the gear-side meshing teeth 40 are meshing teeth, i.e., dog teeth, that make up part of the dog clutch 50. The dog clutch 50 is in an engaged state when the dog teeth mesh with each other, and in a disengaged state when the meshing is released.

[0023] The transmission 26 includes a shift mechanism 60 for moving the switching mechanism 36 in the direction of the rotational axis CL2. The shift mechanism 60 includes shift forks 62 (including 62a, 62b, 62c, and 62d) that fit into the switching mechanism 36, a shift barrel 70, and a shift actuator 66. The shift barrel 70 is formed with shift grooves 76 (including 76a, 76b, 76c, and 76d) that determine the movement position of the switching mechanism 36 in the direction of the rotational axis CL2 via the shift fork 62.

[0024] The shift grooves 76 are formed along the circumferential direction of the shift barrel 70, with a portion of the circumferential direction bent in the axial direction of the shift barrel 70. Therefore, when the shift barrel 70 is rotated, the shift forks 62 are moved in the axial direction of the shift barrel 70 along the groove shape of the shift grooves 76. Furthermore, when the shift forks 62 are moved in the axial direction of the shift barrel 70, the switching mechanism 36 is moved in conjunction with the shift forks 62 toward the rotation axis CL2. The shift grooves 76 each have a different shape relative to the position in the circumferential direction of the shift barrel 70. The shape of the shift grooves 76 is formed so that the transmission 26 sequentially shifts between reverse gear Rev and sixth gear 6th as the shift barrel 70 rotates.

[0025] The transmission 26 changes gears by switching the engagement and disengagement states of the dog clutch 50 as the switching mechanism 36 moves to specified positions in the direction of the rotation axis CL2 in accordance with the rotation of the shift barrel 70. The engagement and disengagement states of the dog clutch 50 include a connected state (synonymous with an engaged state) in which power transmission between the drive gear 32 and the C shaft 52 is possible, and a disconnected state (synonymous with a disengaged state) in which power transmission between the drive gear 32 and the C shaft 52 is disconnected.

[0026] Power is transmitted between the C shaft 52 and the LS differential 58 via a final drive shaft (hereinafter referred to as FD shaft) 56. The C shaft 52 and the FD shaft 56, which function as power transmission shafts for the vehicle, are connected by a spline fit (spline fit portion 54), and the FD shaft 56 and the LS differential 58 are connected by meshing the drive gear 56a with the final gear 58a. The spline fit portion 54 corresponds to the "connection structure between power transmission shafts for the vehicle" of the present invention.

[0027] The vehicle 10 further includes an electronic control device 80 as a controller including control devices of the vehicle 10 related to the control of the engine 12 and the power transmission unit 16. The electronic control device 80 includes a so-called microcomputer.

[0028] The electronic control device 80 is supplied with various signals based on detection values ​​from various sensors provided in the vehicle 10. The various sensors include, for example, an engine rotation speed sensor 90, an input rotation speed sensor 92, an output rotation speed sensor 94, and an accelerator opening sensor 96. The various signals include, for example, an engine rotation speed Ne, an input rotation speed Ni, an output rotation speed No, and an accelerator opening θacc. The output rotation speed No is a rotation speed corresponding to the vehicle speed V.

[0029] The electronic control device 80 outputs various command signals to each device provided in the vehicle 10. These devices include, for example, the engine 12, the hydraulic control circuit 22, and the shift actuator 66. The various command signals include, for example, an engine control command signal Se, a K1 hydraulic control command signal Sk1, and a barrel control command signal Sbrl. The barrel control command signal Sbrl is a control command signal for driving the shift barrel 70 to rotate.

[0030] The electronic control unit 80 calculates the required drive torque Trdem by, for example, applying the accelerator opening θacc and the vehicle speed V to a predetermined drive demand amount map, and outputs an engine control command signal Se for obtaining the engine torque Te that realizes the required drive torque Trdem, taking into consideration the gear ratio γ of the transmission 26, etc. The electronic control unit 80 also determines whether to shift the transmission 26 using, for example, a predetermined shift map, and outputs a barrel control command signal Sbrl for rotating the shift barrel 70 to execute shift control of the transmission 26 as necessary.

[0031] Incidentally, the spline fit (spline fit portion 54) between the C shaft 52 and the FD shaft 56 is a clearance fit, taking assembly and disassembly into consideration. In the conventional example, because the gap between the outer diameter side spline teeth 54a and the inner diameter side spline teeth 54b is large, there is a possibility that the C shaft 52 and the FD shaft 56 will bend at the spline fit portion 54, causing poor tooth contact between the outer diameter side spline teeth 54a and the inner diameter side spline teeth 54b.

[0032] Therefore, in this embodiment, the structure shown in Fig. 2 is used to suppress deflection at the spline fitting portion 54. Fig. 2(a) is a perspective view illustrating the structure of the spline fitting portion 54. Fig. 2(b) is a vertical cross-sectional view of the outer diameter side spline teeth 54a, and Fig. 2(c) is a vertical cross-sectional view of the inner diameter side spline teeth 54b, centered on the rotation axis CL2.

[0033] As shown in FIGS. 2(a) and 2(b), a platform-shaped convex portion 54a2 (shown by diagonal lines) that reduces the gap during engagement is provided at the rear end of the top surface 54a1 of the outer-diameter spline teeth 54a in the insertion direction. The convex portion 54a2 is formed to have a specified convex shape, for example, during the finishing stage of the manufacturing process of the top surface 54a1. As shown in FIGS. 2(a) and 2(c), a platform-shaped convex portion 54b2 (shown by diagonal lines) that reduces the gap during engagement is provided at the rear end of the top surface 54b1 of the inner-diameter spline teeth 54b in the insertion direction. The convex portion 54b2 is formed to have a specified convex shape, for example, during the finishing stage of the manufacturing process of the top surface 54b1. The provision of the convex portion 54a2 and the convex portion 54b2 reduces the gap at both ends of the spline engagement portion 54, thereby suppressing deflection at the spline engagement portion 54 between the C shaft 52 and the FD shaft 56.

[0034] The dimensions of the convex portion 54a2 (e.g., width Xa, length Ya, height Za, not shown tapering or rounding, etc.) and the dimensions and position of the convex portion 54b2 (e.g., width Xb, length Yb, height Zb, distance Wb from the end face, not shown tapering or rounding, etc.) are set in advance to suitable values ​​based on design or experiment. [Example]

[0035] 3 shows an example in which the convex portion 54a2 provided at the rear end of the top surface 54a1 in the insertion direction and the convex portion 54b2 provided at the rear end of the top surface 54b1 in the insertion direction shown in FIG. 2 are changed to a convex portion 54a3 (shown with diagonal lines) provided at the front end of the top surface 54a1 in the insertion direction and a convex portion 54b3 (shown with diagonal lines) provided at the front end of the top surface 54b1 in the insertion direction. In this example as well, the gap at both ends of the spline fitting portion 54 is made small, thereby suppressing deflection at the spline fitting portion 54 between the C shaft 52 and the FD shaft 56. Furthermore, the dimensions and position of the convex portion 54a3 (e.g., width Sa, length Ta, height Ua, distance from the end face Ra, tapering and rounding (not shown), etc.) and the dimensions and position of the convex portion 54b3 (e.g., width Sb, length Tb, height Ub, distance Rb from the end face Rb, tapering and rounding (not shown), etc.) are set in advance to suitable values ​​based on design or experiment, as in Example 1. [Example]

[0036] 4 shows an example in which a cylindrical surface Pa (see FIG. 4(a)) having a diameter Qa and a length Va is provided at the tip of the outer diameter side spline teeth 54a, and a cylindrical surface Pb (see FIG. 4(b)) having a diameter Qb and a length Vb is provided at the tip of the inner diameter side spline teeth 54b, in the spline fitting portion 54 of FIG. 2 (Example 1). The diameter Qa, the length Va, the diameter Qb, and the length Vb are set in advance to suitable values ​​based on design or experimentation, similar to the other dimensions and positions shown in Example 1. In this example, too, the gap at both ends of the spline fitting portion 54 is made small, thereby suppressing deflection at the spline fitting portion 54 between the C shaft 52 and the FD shaft 56.

[0037] As described above, according to the spline fitting portion 54 of Examples 1, 2, and 3, the trapezoidal convex portions 54a2, 54b2 that reduce the gap during fitting are provided at the rear end in the insertion direction of the top faces 54a1 of the outer-diameter side spline teeth 54a and the rear end in the insertion direction of the top faces 54b1 of the inner-diameter side spline teeth 54b, or the trapezoidal convex portions 54a3, 54b3 that reduce the gap during fitting are provided at the front end in the insertion direction of the top faces 54a1 of the outer-diameter side spline teeth 54a and the front end in the insertion direction of the top faces 54b1 of the inner-diameter side spline teeth 54b. This reduces the gap at both ends of the spline fitting portion 54, and suppresses deflection at the spline fitting portion 54 between the C shaft 52 and the FD shaft 56. Furthermore, the protrusions (54a2, 54b2 or 54a3, 54b3) can be formed in the finishing stage of the manufacturing process by reusing the top surfaces 54a1 and 54b1, making production easier, allowing for smaller gaps to be set, and ensuring meshing strength with a space-saving shape. Therefore, without requiring an increase in parts or part precision, deflection at the spline mating portion 54 between the C shaft 52 and the FD shaft 56 is suppressed, and ease of assembly and disassembly is also ensured.

[0038] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0039] For example, in the above-described embodiment, the present invention is applied to the spline fitting portion 54 between the C shaft 52 and the FD shaft 56, which are power transmission shafts provided in the power transmission unit 16 of the vehicle 10, but the present invention is not limited to this. For example, the present invention can be applied to any location where spline fitting is performed with a clearance fit.

[0040] It should be noted that the above is merely one embodiment, 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. [Explanation of symbols]

[0041] 54: Spline fitting portion (connection structure between power transmission shafts for a vehicle) 54a: outer diameter side spline teeth 54a1: top surface 54a2, 54a3, 54b2, 54b3: convex portions 54b: inner diameter side spline teeth 54b1: top surface

Claims

[Claim 1] A connection structure between vehicle power transmission shafts in which outer diameter side spline teeth and inner diameter side spline teeth are fitted together, a rear end of the top surface of the outer diameter side spline teeth in the insertion direction and a rear end of the top surface of the inner diameter side spline teeth in the insertion direction, Alternatively, the tip of the crest surface of the outer diameter side spline tooth in the insertion direction and the tip of the crest surface of the inner diameter side spline tooth in the insertion direction are A connecting structure between power transmission shafts for a vehicle, characterized in that a platform-shaped protrusion is provided to reduce the gap when the shafts are fitted together.

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