Power transmission device

Abstract

The present invention relates to a power transmission device comprising: a differential having a side gear and a pinion gear that engage with each other; a constant-velocity joint connected to a drive shaft; and a ball spline, which couples the side gear and the constant-velocity joint so that the constant-velocity joint can move relative to the side gear in the rotational axis direction, and thus the present invention damps noise and vibration transmitted between the constant-velocity joint and the side gear so as to improve ride quality, and can increase the range of the tilt angle of the constant-velocity joint.

Description

power transmission device

[0001] The present invention relates to a power transmission device, and more particularly, to a power transmission device that can transmit power received from a powertrain of a vehicle to a wheel.

[0002] In general, a vehicle is driven by transmitting power generated from a driving source, such as an engine or a motor, to the wheels through a power transmission device. The power transmission device is configured to distribute the power received from the driving source of the vehicle to the left and right wheels. When the vehicle turns, if the outer wheel and the inner wheel rotate at the same speed, a problem occurs in which one of the outer wheel and the inner wheel slips. Therefore, a differential device is included, which is a device that compensates for the outer wheel and the inner wheel to rotate at different speeds.

[0003] In addition, the power transmission device further includes a constant velocity joint that ensures that power is transmitted equally without change in rotational angular velocity between the side gear of the differential device and the non-linear driven shaft (drive shaft).

[0004] Here, as shown in Fig. 1, the side gear (10) and the constant velocity joint (20) are fastened to each other by serration (S) so that they do not rotate.

[0005] However, in such a conventional power transmission device, since the constant velocity joint (20) is fastened so as not to move relative to the side gear (10), noise and vibration are transmitted as is between the constant velocity joint (20) and the side gear (10), which reduces the ride quality, and there is a problem that the angle range of the constant velocity joint (20) is limited.

[0006] Accordingly, the present invention aims to provide a power transmission device capable of improving ride comfort and increasing the reduction range of a constant velocity joint.

[0007] The present invention provides a power transmission device including a differential device having a side gear and a pinion gear that mesh with each other to achieve the above-mentioned object; a constant velocity joint connected to a drive shaft; and a ball spline that connects the side gear and the constant velocity joint so that the constant velocity joint can move relative to the side gear in the direction of the rotation axis.

[0008] The side gear may include a side gear hole penetrating the rotational axis of the side gear, the constant velocity joint may include a stem inserted into the side gear hole, and the ball spline may include a first groove engraved on an inner surface of the side gear hole, a second groove engraved on an outer surface of the stem, and a ball inserted into the first groove and the second groove.

[0009] The first groove is formed in plurality, and the plurality of first grooves are arranged along the circumferential direction of the side gear hole, the second groove is formed in plurality, and the plurality of second grooves are arranged along the circumferential direction of the stem, and the balls are formed in plurality, and the plurality of balls can be inserted into one of the plurality of first grooves and one of the plurality of second grooves, respectively.

[0010] The plurality of first grooves may each extend in a direction perpendicular to the circumferential direction of the side gear hole, and the plurality of second grooves may each extend in a direction perpendicular to the circumferential direction of the stem.

[0011] The plurality of first grooves may each extend in a direction inclined to the circumference of the side gear hole, and the plurality of second grooves may each extend in a direction inclined to the circumference of the stem.

[0012] The plurality of first grooves include a plurality of 1-1 grooves extending at the same angle with respect to the circumferential direction of the side gear hole and a plurality of 1-2 grooves interposed between each of the plurality of 1-1 grooves, and any 1-1 groove among the plurality of 1-1 grooves and any 1-2 groove adjacent to any 1-1 groove among the plurality of 1-2 grooves may be formed symmetrically with respect to an imaginary plane passing between them and including a central axis of the side gear hole.

[0013] The plurality of second grooves include a plurality of second-1 grooves extending at the same angle with respect to the circumferential direction of the stem and a plurality of second-2 grooves interposed between the plurality of second-1 grooves, and any 2-1 groove among the plurality of second-1 grooves and any 2-2 groove adjacent to any 2-1 groove among the plurality of second-2 grooves may be formed symmetrically with respect to an imaginary plane passing between them and including the central axis of the stem.

[0014] The above ball spline may further include a ball cage supporting the ball.

[0015] The above stem may include a hollow portion.

[0016] The power transmission device according to the present invention includes a differential device having a side gear and a pinion gear that mesh with each other; a constant velocity joint connected to a drive shaft; and a ball spline that connects the side gear and the constant velocity joint so that the constant velocity joint can move relative to the side gear in the direction of the rotation axis based on the side gear; thereby improving riding comfort by attenuating noise and vibration transmitted between the constant velocity joint and the side gear, and increasing the angle range of the constant velocity joint.

[0017] Figure 1 is an exploded perspective view showing the connection structure between a constant velocity joint and a differential device in a conventional power transmission device.

[0018] FIG. 2 is an exploded perspective view showing the connection structure between a constant velocity joint and a differential device in a power transmission device according to one embodiment of the present invention.

[0019] FIG. 3 is an exploded perspective view illustrating a connection structure between a constant velocity joint and a differential device in a power transmission device according to another embodiment of the present invention.

[0020] Hereinafter, the power transmission device according to the present invention will be described in detail with reference to the attached drawings.

[0021] FIG. 2 is an exploded perspective view illustrating a connection structure between a constant velocity joint and a differential device in a power transmission device according to one embodiment of the present invention.

[0022] Referring to the attached FIG. 2, a power transmission device according to one embodiment of the present invention may include a differential device having a side gear (110) and a pinion gear that mesh with each other to compensate for the outer wheel and the inner wheel of a vehicle to rotate at different speeds, a constant velocity joint (200) connected to a drive shaft (not shown) connected to a wheel, and a ball spline (BS) that connects the side gear (110) and the constant velocity joint (200) so that the constant velocity joint (200) can move relative to the side gear (110) in the direction of the rotation axis.

[0023] Here, the side gear (110) includes a side gear hole (112) penetrating the rotation axis of the side gear (110), the constant velocity joint (200) includes a stem (212) inserted into the side gear hole (112), and the ball spline (BS) may include a first groove (112a) engraved on the inner surface of the side gear hole (112), a second groove (212a) engraved on the outer surface of the stem (212), and a ball (300) inserted into the first groove (112a) and the second groove (212a).

[0024] The above first groove (112a) is formed in plurality, and the plurality of first grooves (112a) can be arranged along the circumferential direction of the side gear hole (112).

[0025] And, each of the plurality of first grooves (112a) can extend in a direction perpendicular to the circumferential direction of the side gear hole (112).

[0026] The above second groove (212a) can be formed to correspond to the plurality of first grooves (112a).

[0027] Specifically, the second grooves (212a) are formed in the same number as the plurality of first grooves (112a), and the plurality of second grooves (212a) can be arranged along the circumferential direction of the stem (212).

[0028] And, each of the plurality of second grooves (212a) extends in a direction perpendicular to the circumference of the stem (212) and may face one of the plurality of first grooves (112a).

[0029] The above balls (300) are formed in plurality, and the plurality of balls (300) can be inserted into one of the plurality of first grooves (112a) and one of the plurality of second grooves (212a), respectively.

[0030] Here, the plurality of balls (300) may be provided in a number greater than the number of the plurality of first grooves (112a) and the number of the plurality of second grooves (212a), so as to be configured in a double row. That is, at least two balls (300) may be inserted into the first grooves (112a) and the second grooves (212a) that form a pair with each other.

[0031] In addition, the ball spline (BS) may further include a ball cage (400) that supports the plurality of balls (300) so that the plurality of balls (300) do not come off.

[0032] Meanwhile, the stem (212) may include a hollow space inside the stem (212) to reduce weight and cost and improve natural frequency.

[0033] Hereinafter, the operational effects of the power transmission device according to the present embodiment will be described.

[0034] That is, when the side gear (110) rotates, the tripod housing (210) of the constant velocity joint (200) rotates together with the side gear (110), and the spider assembly (not shown) that reciprocates inside the tripod housing (210) and articulately connects the tripod housing (210) and the drive shaft (not shown) rotates together with the tripod housing (210), so that power transmitted from the vehicle's driving source to the side gear (110) can be transmitted to the wheels.

[0035] Here, since the side gear (110) is fastened to the constant velocity joint (200) (more precisely, the tripod housing (210)) by the ball spline (BS), the constant velocity joint (200) can move relative to the side gear (110) in the direction of the rotation axis without the side gear (110) rotating with respect to the constant velocity joint (200). That is, the constant velocity joint (200) can slide in a direction approaching and away from the side gear (110). As a result, noise and vibration transmitted between the constant velocity joint (200) and the side gear (110) can be reduced, thereby improving ride comfort. In addition, the angle range of the constant velocity joint (200) can be increased.

[0036] Meanwhile, in the present embodiment, the plurality of first grooves (112a) each extend in a direction perpendicular to the circumferential direction of the side gear hole (112), and the plurality of second grooves (212a) each extend in a direction perpendicular to the circumferential direction of the stem (212). However, in this case, backlash may occur between the side gear (110) and the constant velocity joint (200).

[0037] In consideration of this, as illustrated in FIG. 3, in order to suppress backlash between the side gear (110) and the constant velocity joint (200) by the ball spline (BS), a plurality of first grooves (112a) may each extend in an inclined direction with respect to the circumference of the side gear hole (112), and a plurality of second grooves (212a) may each extend in an inclined direction with respect to the circumference of the stem (212).

[0038] Specifically, the plurality of first grooves (112a) may include a plurality of first-first grooves (112aa) extending at the same angle with respect to the circumferential direction of the side gear hole (112) and a plurality of first-second grooves (112ab) interposed between the plurality of first-first grooves (112aa).

[0039] And, any 1-1 groove (112aa) among the plurality of 1-1 grooves (112aa) and any 1-2 groove (112ab) adjacent to any 1-1 groove (112aa) among the plurality of 1-2 grooves (112ab) can be formed symmetrically with respect to an imaginary plane that passes between them and includes the central axis of the side gear hole (112).

[0040] The plurality of second grooves (212a) may be formed to correspond to the plurality of first grooves (112a).

[0041] That is, the plurality of second grooves (212a) may include a plurality of second-first grooves (212aa) extending at the same angle with respect to the circumferential direction of the stem (212) and a plurality of second-second grooves (212ab) interposed between the plurality of second-first grooves (212aa).

[0042] And, any 2-1 groove (212aa) among the plurality of 2-1 grooves (212aa) and any 2-2 groove (212ab) adjacent to any 2-1 groove (212aa) among the plurality of 2-2 grooves (212ab) can be formed symmetrically with respect to an imaginary plane that passes between them and includes the central axis of the stem (212).

[0043] In this case, the ball (300) inserted into the first groove (112a) and the second groove (212a) can move in a direction parallel to the rotation axis, but since the movement in the direction of the rotation axis is suppressed to a certain degree by the inclined first groove (112a) and the second groove (212a), backlash between the side gear (110) and the constant velocity joint (200) can be suppressed.

Claims

1. A differential device having a side gear (110) and a pinion gear that mesh with each other; Constant velocity joint (200) connected to the drive shaft; and A power transmission device including a ball spline (BS) that connects the side gear (110) and the constant velocity joint (200) so that the constant velocity joint (200) can move relative to the side gear (110) in the direction of the rotation axis.

2. In paragraph 1, The above side gear (110) includes a side gear hole (112) penetrating the rotation axis of the side gear (110), The above constant velocity joint (200) includes a stem (212) inserted into the side gear hole (112), The above ball spline (BS) is a power transmission device including a first groove (112a) engraved on the inner surface of the side gear hole (112), a second groove (212a) engraved on the outer surface of the stem (212), and a ball (300) inserted into the first groove (112a) and the second groove (212a).

3. In paragraph 2, The above first groove (112a) is formed in plurality, and the plurality of first grooves (112a) are arranged along the circumferential direction of the side gear hole (112). The second groove (212a) is formed in plurality, and the plurality of second grooves (212a) are arranged along the circumferential direction of the stem (212). A power transmission device in which the above balls (300) are formed in plurality, and the plurality of balls (300) are each inserted into one of the plurality of first grooves (112a) and one of the plurality of second grooves (212a).

4. In paragraph 3, The plurality of first grooves (112a) above each extend in a direction perpendicular to the circumference of the side gear hole (112), A power transmission device in which the plurality of second grooves (212a) each extend in a direction perpendicular to the circumference of the stem (212).

5. In paragraph 3, The plurality of first grooves (112a) above each extend in an inclined direction in the circumferential direction of the side gear hole (112), A power transmission device in which the plurality of second grooves (212a) each extend in an inclined direction relative to the circumference of the stem (212).

6. In paragraph 5, The plurality of first grooves (112a) include a plurality of first-first grooves (112aa) extending at the same angle with respect to the circumferential direction of the side gear hole (112) and a plurality of first-second grooves (112ab) interposed between the plurality of first-first grooves (112aa). A power transmission device in which any 1-1 groove (112aa) among the plurality of 1-1 grooves (112aa) and any 1-2 groove (112ab) adjacent to any 1-1 groove (112aa) among the plurality of 1-2 grooves (112ab) are formed symmetrically with respect to an imaginary plane that passes between them and includes the central axis of the side gear hole (112).

7. In paragraph 6, The plurality of second grooves (212a) include a plurality of second-first grooves (212aa) extending at the same angle with respect to the circumferential direction of the stem (212) and a plurality of second-second grooves (212ab) interposed between the plurality of second-first grooves (212aa). A power transmission device in which any 2-1 groove (212aa) among the plurality of 2-1 grooves (212aa) and any 2-2 groove (212ab) adjacent to any 2-1 groove (212aa) among the plurality of 2-2 grooves (212ab) are formed symmetrically with respect to an imaginary plane that passes between them and includes the central axis of the stem (212).

8. In paragraph 2, The above ball spline (BS) is a power transmission device further including a ball cage (400) that supports the ball (300).

9. In paragraph 2, The above stem (212) is a power transmission device including a hollow body.

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