Power transmission device

Abstract

The present invention provides a power transmission device that can improve the reliability of the drive hub without changing the layout. [Solution] The power transmission device is interposed between an engine and a transmission and is capable of transmitting power from the engine to the transmission, and comprises: an input shaft having a spline portion and connected to a flywheel mounted on the output shaft of the engine via a damper fitted to the spline portion; a wet friction clutch interposed between the input shaft and the transmission and capable of transmitting the rotation of the input shaft to the transmission; a working fluid supply unit that rotates on the same axis as the input shaft and supplies working fluid to the wet friction clutch; and a drive member provided separately from the damper and press-fitted along the axial direction of the input shaft, which transmits the rotation of the input shaft to the working fluid supply unit.

Description

Technical Field

[0001] The present disclosure relates to a power transmission device.

Background Art

[0002] A power transmission device for transmitting the power of an engine to a transmission is provided between the engine and the transmission. In this power transmission device, the input shaft is connected to a flywheel mounted on the output shaft of the engine via a damper for absorbing the rotational fluctuations of the engine, or a fluid coupling such as a torque converter. A spline is formed on the input shaft of the power transmission device, and the connection between the damper or the fluid coupling and the input shaft is made via this spline.

[0003] On the other hand, a clutch for blocking the transmission of power from the engine to the transmission may be provided between the input shaft of the power transmission device and the transmission. When a wet friction clutch is used as such a clutch, an operating fluid supply unit such as a hydraulic pump is required to supply the operating fluid to the wet friction clutch.

[0004] For example, in Patent Document 1, the operating fluid supply unit is constituted by a gear pump, and a drive hub that is spline-coupled to the input shaft is provided between the damper and the pump gear separately from the pump gear of the gear pump. The drive hub transmits the rotation of the input shaft to the pump gear by fitting a plurality of protrusions into the pump gear.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the power transmission device described in Patent Document 1, the drive hub is assembled to a predetermined position in the axial direction of the input shaft by bringing it into contact with a damper, thereby suppressing the axial movement of the drive hub.

[0007] In a power transmission system with this configuration, the drive hub is in contact with the damper, which can cause power from the engine to be transmitted directly to the drive hub. This results in increased surface pressure on the part of the drive hub that engages with the spline of the input shaft. Furthermore, because the engagement portion of the drive hub with the spline is short, it is prone to wear, potentially reducing the reliability of the drive hub.

[0008] Therefore, the purpose of this disclosure is to provide a power transmission device that can improve the reliability of the drive hub without changing the layout. [Means for solving the problem]

[0009] This disclosure is made to solve at least some of the aforementioned problems and can be implemented in the following forms or applications.

[0010] The power transmission device according to this application example is interposed between an engine and a transmission and is capable of transmitting power from the engine to the transmission, and is characterized by comprising: an input shaft having a spline portion and connected to a flywheel mounted on the output shaft of the engine via a damper fitted to the spline portion; a wet friction clutch interposed between the input shaft and the transmission and capable of transmitting the rotation of the input shaft to the transmission; a working fluid supply unit that rotates on the same axis as the input shaft and supplies working fluid to the wet friction clutch; and a drive member provided separately from the damper and press-fitted along the axial direction of the input shaft, which transmits the rotation of the input shaft to the working fluid supply unit.

[0011] In this way, the drive hub is press-fitted along the axial direction of the input shaft, generating frictional force between the input shaft and the drive hub, allowing it to be assembled in a predetermined position along the axial direction of the input shaft. Furthermore, since the drive hub does not come into contact with the damper, power from the engine is not directly transmitted to the drive hub. In addition, since the drive hub does not engage with the spline portion of the input shaft, wear on the inner surface of the drive hub can be suppressed. As a result, the reliability of the drive hub can be improved without changing the layout. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view showing the overall configuration of a power transmission device according to one embodiment of the present invention. [Figure 2] This is a magnified view of a part of the power transmission device shown in Figure 1. [Figure 3] Figure 1 is a side view of the drive hub used in the power transmission device. [Figure 4] Figure 3 shows the drive hub viewed from one end. [Figure 5] This is a view of the drive hub in Figure 3 from the other end. [Figure 6] This is a view of the pump gear of the gear pump used in the power transmission device shown in Figure 1, along the central axis. [Best Mode for Carrying Out the Invention]

[0013] An embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a schematic cross-sectional view showing the overall configuration of the power transmission device of this embodiment. Figure 2 is an enlarged view of a part of the power transmission device of this embodiment. The power transmission device 1 is interposed between the engine and the transmission (neither of which are shown).

[0014] A flywheel 4 is attached and fixed to the end of the engine's output shaft 2 by multiple bolts 6, and the flywheel 4 rotates together with the output shaft 2 when the engine is running.

[0015] On one hand, the power transmission device 1 includes a hydraulic pump (working fluid supply unit) 8 and a wet friction clutch 10. The hydraulic pump 8 is a gear pump, and includes a pump casing 14 fixed to the housing 12 of the power transmission device 1, and a pump gear (rotary input member) 16 that rotates within the pump casing 14 to supply externally the hydraulic oil, which is the working fluid with increased pressure. Also, the wet friction clutch 10 includes an input shaft 18 arranged on the same axis as the output shaft 2 of the engine, and the output side is connected to the input shaft (not shown) of the transmission.

[0016] The wet friction clutch 10 is configured to be actuated by the hydraulic oil supplied from the hydraulic pump 8. When connected, it transmits the power from the engine to the transmission, and when disengaged, it blocks the transmission of power from the engine to the transmission. The wet friction clutch 10 itself is a conventionally known component, and detailed description of its structure is omitted here.

[0017] The input shaft 18 of the wet friction clutch 10 penetrates through the pump gear 16 of the hydraulic pump 8 and extends towards the engine side. On its peripheral surface, a spline portion 20 with splines parallel to the central axis is formed over a predetermined region starting from the engine-side end.

[0018] A damper device 22 for transmitting the power of the engine to the input shaft 18 while absorbing the rotational fluctuations and vibrations of the engine is interposed between the flywheel 4 and the input shaft 18. The damper device 22 includes an annular input plate 26 fixed to the flywheel 4 by a plurality of bolts 24 on the input side, and a damper hub 30 connected to the input plate 26 via a damper spring 28 on the output side.

[0019] A through hole 32 having a central axis that coincides with the central axis of the output shaft 2 of the engine is formed in the damper hub 30 of the damper device 22. Teeth corresponding to the splines formed on the spline portion 20 of the input shaft 18 are formed on the inner peripheral surface of the through hole 32. The input shaft 18 is inserted into the through hole 32 of the damper hub 30, and the damper hub 30 is fitted to the spline portion 20 of the input shaft 18.

[0020] A drive hub 34, which is provided separately from the damper hub 30 and has a cylindrical shape through which the input shaft 18 passes, is mounted between the damper hub 30 of the damper 22 and the pump gear 16 of the hydraulic pump 8. The inner peripheral surface of the drive hub 34 is slightly smaller in diameter than the input shaft 18, so that it is press-fitted along the axial direction from the end of the input shaft 18 and fixed at a predetermined position. By being fixed at the predetermined position, a gap is provided between the drive hub 34 and the damper hub 30 of the damper 22 (see FIG. 2). That is, the drive hub 34 is assembled so as not to contact the damper hub 30. Further, when the drive hub 34 is press-fitted, a frictional force is generated between the drive hub 34 and the input shaft 18, and the drive hub 34 rotates integrally with the input shaft 18. In the present embodiment, as shown in FIG. 2, a stepped portion 18a having a larger diameter than the press-fitting surface of the outer peripheral surface of the input shaft 18 that contacts the drive hub 34 is formed. The stepped portion 18a positions the drive hub 34, and the position where the drive hub 34 abuts against the stepped portion 18a of the input shaft 18 is the predetermined position.

[0021] Also, the outer peripheral surface of the drive hub 34 is rotatably supported by the pump casing 14 of the hydraulic pump 8 via a first seal ring (first seal member) 36, and the inner peripheral surface of the drive hub 34 is press-fitted to the outer peripheral surface of the input shaft 18 via a second seal ring (second seal member) 38. Therefore, the drive hub 34 is assembled by being press-fitted to the input shaft 18 and is supported by the pump casing 14 and the input shaft 18 via two seal rings, so that it is possible to favorably suppress the generation of vibration when the drive hub 34 rotates.

[0022] FIG. 3 is a side view of the drive hub 34, and FIGS. 4 and 5 are views seen in the axial direction of the drive hub 34 from one end side (the right side in FIG. 3) and the other end side (the left side in FIG. 3) of the drive hub 34, respectively. As shown in FIGS. 3 to 5, the drive hub 34 includes a hub body 34a having a cylindrical shape, a plurality of protruding portions 34b extending in the axial direction of the drive hub 34 from one end of the hub body 34a, and a tool engagement portion 34c formed on the other end side of the hub body 34a and having a hexagonal cross-sectional outer shape.

[0023] The protruding portions 34b are claw-shaped and are arranged at equal intervals along the outer circumference of the hub body 34a, as shown in Figure 4. The inner circumferential surface of the hub body 34a is smooth and is formed to be larger in diameter than the outer diameter of the spline portion 20 of the input shaft 18.

[0024] Figure 6 shows the pump gear 16 of the hydraulic pump 8 as viewed from the drive hub 34 side in the direction of the central axis. The pump gear 16 has a planar portion 16a perpendicular to the central axis of the input shaft 18, and as shown in Figure 6, a through hole 16b is formed in the central part of this planar portion 16a through which the input shaft 18 of the wet friction clutch 10 passes. Around the through hole 16b, a plurality of fitting holes 16c are formed at equal intervals so as to surround the input shaft 18 that passes through the through hole 16b. The number of these fitting holes 16c matches the number of protrusions 34b provided on the drive hub 34, and as shown in Figure 1, when the drive hub 34 is mounted on the input shaft 18, the protrusions 34b of the drive hub 34 fit into the fitting holes 16c of the pump gear 16.

[0025] As described above, the drive hub 34 is press-fitted onto the input shaft 18, so that it rotates integrally with the input shaft 18. Therefore, when the protrusion 34b of the drive hub 34 fits into the fitting hole 16c of the pump gear 16, the rotation of the input shaft 18 is transmitted to the pump gear 16, causing the pump gear 16 to rotate and the hydraulic pump 8 to operate.

[0026] With the power transmission device 1 configured in this way, engine power is transmitted from the flywheel 4 fixed to the output shaft 2 to the input shaft 18 of the wet friction clutch 10 via the damper 22. When the wet friction clutch 10 is engaged, engine power is transmitted to the transmission via the wet friction clutch 10, while when the wet friction clutch 10 is disengaged, the transmission of engine power to the transmission is interrupted.

[0027] Furthermore, a portion of the engine power transmitted to the input shaft 18 is transmitted to the pump gear 16 of the hydraulic pump 8 via the drive hub 34 pressed into the input shaft 18, causing the pump gear 16 to rotate and operate the hydraulic pump 8. The hydraulic fluid, whose pressure is increased by the operation of the hydraulic pump 8, is supplied to the wet friction clutch 10 and used to operate the wet friction clutch 10.

[0028] Since the flywheel 4 is fixed to the engine's output shaft 2, the flywheel 4 fluctuates due to vibrations associated with engine operation, and this fluctuation is transmitted to the damper 22 via the flywheel 4. At this time, the drive hub 34 is provided separately from the damper hub 30 of the damper 22, and a gap is provided between them, so the fluctuations of the damper 22 due to the fluctuations of the flywheel 4 are not directly transmitted to the drive hub 34. Therefore, wear and deformation of the drive hub 34, the first seal ring 36, and the second seal ring 38 due to the transmission of fluctuations can be effectively suppressed, and vibration noise and failure of the hydraulic pump 8 caused by fluctuations and vibrations transmitted from the engine can be effectively suppressed.

[0029] As described above, in this embodiment, the power transmission device 1 has a drive hub 34 that is press-fitted along the axial direction of the input shaft 18, generating frictional force between the input shaft 18 and the drive hub 34, allowing it to be assembled to a predetermined position in the axial direction of the input shaft 18. Furthermore, since the drive hub 34 does not come into contact with the damper hub 30 of the damper 22, power from the engine is not directly transmitted to the drive hub 34. Moreover, since the drive hub 34 does not engage with the spline portion 20 of the input shaft 18, wear on the inner surface of the drive hub 34 can be suppressed. This improves the reliability of the drive hub without changing the layout.

[0030] This concludes the description of the power transmission device according to the embodiment of the present invention, but the present invention is not limited to the above embodiment.

[0031] In the above embodiment, the drive hub 34 is provided with four claw-shaped protrusions 34b at equal intervals along the outer circumference of the hub body 34a. However, the number, shape, and arrangement of the protrusions 34b are not limited to this and can be modified in various ways. Needless to say, however, fitting holes 16c, whose number, shape, and arrangement correspond to the protrusions 34b provided on the drive hub 34, must be provided on the flat surface 16a of the pump gear 16.

[0032] Furthermore, although the hydraulic pump in the above embodiment is a gear pump, the type of hydraulic pump is not limited to this, and any hydraulic pump having a rotating input member that rotates on the same axis as the input shaft, such as the gear section of a drive gear, is acceptable.

[0033] Furthermore, in the above embodiment, hydraulic oil was used as the working fluid for the wet friction clutch, but the type of working fluid is not limited to this. [Explanation of Symbols]

[0034] 1. Power transmission device 2 Output shafts 4 Flywheel 6 volts 8. Hydraulic pump (working fluid supply unit) 10 Wet friction clutch 12 Housing 14 Pump Casing 16 Pump gear (rotation input component) 16a Flat part 16b Through hole 16c mating hole 18 input axes 18a Stepped section 20 Spline section 22 Damper 24 volts 26 Input Plate 28 Damper Springs 30 Damper Hub 32 Through holes 34. Drive hub (drive component) 34a Hub body 34b Protrusion 34c Tool engaging part 36. First seal ring (first seal member) 38. Second seal ring (second seal member)

Claims

[Claim 1] A power transmission device interposed between an engine and a transmission, capable of transmitting power from the engine to the transmission, An input shaft having a spline portion and connected to a flywheel mounted on the output shaft of the engine via a damper fitted to the spline portion, A wet friction clutch is interposed between the input shaft and the transmission, and is capable of transmitting the rotation of the input shaft to the transmission. A working fluid supply unit that rotates on the same axis as the input shaft and supplies working fluid to the wet friction clutch, A power transmission device comprising a drive member provided separately from the damper and press-fitted along the axial direction of the input shaft, which transmits the rotation of the input shaft to the working fluid supply unit.

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