JP2023172375A - Power transmission device of vehicle - Google Patents

Abstract

To prevent damage of an oil seal provided at an opening of a housing and improve sealability in an oil seal slide portion without impairing maintainability during assembly of a drive shaft.SOLUTION: A drive shaft 5 of a power transmission device is engaged at one end with a side gear 34 of a differential gear and is rotatably supported by a differential case 32 through a ball bearing 40 for an inner shaft which is fitted in the drive shaft 5, forming a space between itself and an end surface 52a of a seal journal part 52. Further, the drive shaft 5 has a cylindrical sleeve 60 which is fitted in an outer peripheral surface of the seal journal part 52. The sleeve 60 is formed so as to cover an area from the seal journal part 52 to the space and includes a cutout part 63.SELECTED DRAWING: Figure 3

Description

The present invention relates to a power transmission device for a vehicle.

Conventionally, a differential case is rotatably supported by a housing via a bearing, a drive shaft is inserted into the differential case, an oil supply path is provided in the housing, and an oil supply path is provided between the housing and the drive shaft. A power transmission device for a vehicle is known that includes an oil seal (see Patent Document 1).

JP 2019-100447 Publication

In the assembly process of such a power transmission device for a vehicle, when assembling a drive shaft to a differential case, the drive shaft is inserted into an oil seal provided in an opening of the housing. At this time, it is necessary to insert the drive shaft so that the dust lip and main lip of the oil seal will not be damaged by turning over.

By the way, some vehicle power transmission devices have a drive shaft supported by a ball bearing on a differential case. In such a power transmission device for a vehicle, when a drive shaft is inserted into a differential case, a ball bearing is press-fitted into the drive shaft in advance and then inserted into the differential case. The drive shaft passes through an oil seal provided in an opening of the housing, and a spline portion on the tip side of the drive shaft is fitted into a spline portion of the differential side gear.

As mentioned above, the ball bearing is press-fitted into the drive shaft, but there is a gap (a gap for disassembling the ball bearing) between the ball bearing and the end face of the journal part of the drive shaft (which becomes the sliding part of the oil seal). A tool (for example, a bearing puller) for removing the ball bearing from the inner shaft when replacing the ball bearing can be engaged in this gap for disassembling the ball bearing.

However, when inserting the drive shaft into the differential case, when the lip of the oil seal passes through the gap for disassembling the ball bearing, the end face of the journal part of the drive shaft gets caught on the dust lip or main lip of the oil seal. There was a risk that the lip of the oil seal would be damaged and oil would leak from the oil seal.

The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent damage to the oil seal provided in the opening of the housing when assembling the drive shaft without impairing maintainability, and to An object of the present invention is to provide a power transmission device for a vehicle that can improve sealing performance in an oil seal sliding portion.

The present invention has been made to solve at least part of the above-mentioned problems, and can be realized as the following aspects or application examples.

The power transmission device for a vehicle according to this application example is a differential that differentially transmits a driving force transmitted from a power source mounted on a vehicle, and transmits the driving force to a drive shaft connected to each drive wheel of the vehicle. a gear, a differential case that accommodates the differential gear, a housing that rotatably supports the differential case via a first bearing, and an oil seal that is provided in an opening of the housing and seals a journal portion of the drive shaft. , wherein the drive shaft has one end engaged with a side gear of the differential gear, and has a gap with respect to an end surface of the journal portion. It has a cylindrical sleeve that is rotatably supported by the differential case via a second bearing that is fitted to the drive shaft and that is fitted to the outer peripheral surface of the journal part, and the sleeve is , characterized in that it is formed so as to cover from the journal part to the gap, and includes at least two or more notches.

In this way, a cylindrical sleeve is fitted onto the outer circumferential surface of the journal part that is the sliding surface with the oil seal in the drive shaft, and the sleeve covers the gap for disassembling the ball bearing. By doing this, when inserting the drive shaft into the differential gear through the opening in the housing, the end face of the journal part of the drive shaft can be inserted without getting caught in the dust lip or main lip of the oil seal, thereby preventing damage to the oil seal. It can be prevented.

Furthermore, since the sleeve has a notch, in the event that the ball bearing is removed from the drive shaft, the claw of the puller, which is a tool, can be inserted through the notch through the gap for disassembling the ball bearing, and then It becomes possible to hook the second bearing onto the bearing and remove the second bearing. In other words, the maintainability of the power transmission device has been maintained.

Thereby, it is possible to prevent damage to the oil seal provided at the end of the housing during assembly of the drive shaft, and to improve sealing performance at the oil seal sliding portion, without impairing maintainability.

1 is a schematic configuration diagram of a vehicle equipped with a power transmission device for a vehicle according to an embodiment of the present invention. 1 is an overall sectional view of a power transmission device for a vehicle according to an embodiment of the present invention. 1 is a sectional view of a main part of a power transmission device for a vehicle according to an embodiment of the present invention. FIG. 3 is a detailed view of the sleeve. FIG. 3 is a detailed diagram of an oil seal. It is an explanatory view showing a process of assembling a drive shaft to a differential mechanism.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a vehicle power transmission device according to an embodiment of the present invention.

As shown in FIG. 1, a vehicle 1 according to the present embodiment is an electric truck including a ladder frame 2, a cab 3, and a drive unit 4.

The ladder frame 2 has a pair of left and right side frames 2a and a plurality of cross members 2b. The side frames 2a extend along the vehicle longitudinal direction of the vehicle 1, and are mutually arranged parallel to the vehicle width direction. The plurality of cross members 2b extend in the vehicle width direction and connect the pair of side frames 2a. The ladder frame 2 supports the cab 3, the drive unit 4, and other heavy objects mounted on the vehicle 1.

The cab 3 is a structure including a driver's seat (not shown), and is provided above the front part of the ladder frame 2.

The drive unit 4 is located at the rear of the vehicle, and is connected to the rear wheels 6 via a pair of left and right drive shafts 5. Two rear wheels 6 are arranged on each side. In the vehicle 1 according to the present embodiment, driving force is transmitted from the drive unit 4 so that the rear wheels 6 function as drive wheels, and the vehicle 1 can travel. Although not shown, front wheels are provided at the front of the vehicle.

The drive unit 4 includes a motor 10 as a drive source, a speed change mechanism 20, and a differential mechanism 30. The motor 10 generates the driving force necessary for driving the vehicle 1 by being supplied with AC power from a battery (not shown) via an inverter. The speed change mechanism 20 of this embodiment is a speed reducer, includes a plurality of gears, and outputs the reduced speed to the differential mechanism 30 by decelerating the rotation input from the motor 10 . The differential mechanism 30 distributes the rotational driving force input from the transmission mechanism 20 to the left and right rear wheels 6. That is, the drive unit 4 reduces the rotational driving force of the motor 10 to a rotational speed suitable for traveling of the vehicle 1 and transmits it to the drive shaft 5 via the transmission mechanism 20 and the differential mechanism 30. Thereby, the drive unit 4 rotates the rear wheels 6 via the drive shaft 5 to cause the vehicle 1 to travel.

Next, FIG. 2 is an overall sectional view of a power transmission device for a vehicle according to an embodiment of the invention. Hereinafter, the internal structure of the power transmission device will be explained based on the same figure.

In the transmission mechanism 20 and the differential mechanism 30, a plurality of gears are housed in a housing 21 (so-called gear box). The transmission mechanism 20 has three shafts, an input shaft 22, an intermediate shaft 23, and an output shaft 24, which are rotatably supported within a housing 21. Each of the shafts 22, 23, and 24 extends parallel to the vehicle width direction.

The input shaft 22 has one end connected to the motor output shaft 11 of the motor 10, and is provided with a first gear 25a. The intermediate shaft 23 is provided with a second gear 25b that meshes with the first gear 25a, and a third gear 25c. The output shaft 24 is provided with a fourth gear 25d that meshes with the third gear 25c, and a fifth gear 25e that meshes with the ring gear 31 of the differential mechanism 30. The diameter of each gear is set so that the reduction ratio required of the transmission mechanism 20 can be achieved. The transmission mechanism 20 is configured to be able to convert high rotation, low torque rotational driving force input from the motor 10 side into low rotation, high torque and output the same.

A differential mechanism 30 is also accommodated within the housing 21, and the ring gear 31 of the differential mechanism 30 meshes with the fifth gear 25e, which is the final gear of the transmission mechanism 20. The ring gear 31 is integrally connected to a differential case 32, and the differential case 32 is rotatably supported with respect to the housing 21 via a pair of left and right differential case ball bearings 32a (first bearings). The differential case 32 accommodates a differential gear consisting of a pinion gear 33 and a side gear 34, and the drive shaft 5 is engaged with the side gear 34.

Specifically, each of the left and right drive shafts 5 has an inner shaft 5a on the inside in the vehicle width direction, and an outer shaft 5b on the outside in the vehicle width direction (in FIG. 2, only the inner end of the outer shaft 5b in the vehicle width direction is shown). They are connected and coaxially form a single unit. An inner end portion of the inner shaft 5 a in the vehicle width direction, that is, one end portion of the drive shaft 5 is spline-coupled to a side gear 34 of the differential mechanism 30 . The inner shaft 5a passes through the opening of the housing 21 and is inserted into the side gear 34, and is rotatably supported by the differential case 32 via an inner shaft ball bearing 40 (second bearing).

A certain amount of oil for gear lubrication is stored in the housing 21, and an oil seal 70 provides a liquid-tight seal between the opening of the housing 21 and the inner shaft 5a. This seal structure will be explained in detail below.

FIG. 3 is a cross-sectional view of the main parts of the vehicle power transmission device of this embodiment, FIG. 4 is a detailed view of the sleeve, and FIG. 5 is a detailed view of the oil seal. Explain the structure. Note that these FIGS. 3 are enlarged views of the connecting portion between the drive shaft 5 and the differential mechanism 30 on the left side of the vehicle, and the sleeve in FIG. 4 and the oil seal in FIG. 5 are also on the left side of the vehicle. A detailed explanation of the right side of the vehicle, which has the same basic configuration, will be omitted.

As shown in FIG. 3, the inner shaft 5a has a spline portion 50, a bearing press-fit portion 51, a seal journal portion 52, and a flange portion 53 from the tip side (inner side in the vehicle width direction) to the outer shaft side (outer side in the vehicle width direction). is formed so that its diameter gradually increases.

The spline portion 50 has external spline teeth formed on its outer peripheral surface, and the external spline teeth mesh with the internal spline teeth of the side gear 34 . The bearing press-fitting portion 51 has an outer circumferential surface that gradually expands in diameter from the spline outer teeth and into which the annular inner shaft ball bearing 40 is press-fitted.

The seal journal portion 52 has an end surface 52a that is enlarged in diameter perpendicularly to the radial direction with a certain gap from the bearing press-fit portion 51. A sleeve 60, which will be described later, is fitted onto the outer peripheral surface of the seal journal portion 52, and is in contact with an oil seal 70 via the sleeve 60.

The flange portion 53 has a hollow disk shape whose diameter expands perpendicularly from the seal journal portion, and a plurality of bolt insertion holes 53a penetrating in the vehicle width direction are formed in the circumferential direction at the outer edge portion. . The outer shaft 5b is also formed with a flange portion 54 having holes 54a for bolt insertion, and when bolts 55 are inserted into the respective holes 53a and 54a and fastened with nuts 56, the inner shaft 5a and the outer shaft 5b are connected. is flange connected.

As shown in FIG. 4, the sleeve 60 is a metal cylindrical member whose outer peripheral surface is heat-treated and polished to a specified roughness to facilitate sliding on the oil seal 70. Specifically, the sleeve 60 includes a cylindrical sleeve base 61, a sleeve tip 62 whose outer diameter is tapered on the inside of the sleeve base 61 in the vehicle width direction, and a sleeve base 61 at the sleeve tip 62. It has a pair of rectangular notches 63 on the sides.

The outer diameter of the sleeve base 61 is slightly larger than the outer diameter of the ball bearing 40 for the inner shaft, and the outer diameter of the end surface of the sleeve tip 62 (sleeve tip surface) is approximately the same diameter as the outer diameter of the ball bearing 40 for the inner shaft. It is.

The pair of notches 63 are formed at symmetrical positions with respect to the axis of the sleeve 60, and have a notch width in the circumferential direction that allows the claws of the bearing puller to pass through. Note that the bearing puller is a tool for pulling out the inner shaft ball bearing 40 from the inner shaft 5a. Although not shown, the bearing puller has claws arranged on both sides of a male-threaded mandrel, and the mandrel is rotated by hooking the claws onto the ball bearing, applying the tip of the mandrel to the end surface of the inner shaft 5a, and rotating the mandrel. It is possible to pull out the ball bearing using the axial force of the male screw.

The sleeve 60 has a length such that the sleeve tip 62 protrudes inward in the vehicle width direction from the end surface 52a of the seal journal portion 52. The notch portion 63 has an axial length (notch depth) that is outside the end surface 52a of the seal journal portion 52 in the vehicle width direction.

That is, as shown in FIG. 3, the sleeve 60 covers most of the gap between the end surface 52a of the seal journal portion 52 and the inner shaft ball bearing 40 (the gap for disassembling the bearing). On the other hand, the notch part 63 is formed so that the claw part of the bearing puller enters the gap for disassembling the bearing through the notch part 63 and is caught on the outer surface in the vehicle width direction of the ball bearing for the inner shaft.

The oil seal 70 is an annular elastic body (for example, rubber) provided on the inner periphery of a circular opening formed in the housing 21 . Specifically, as shown in FIG. 5, the oil seal 70 includes a seal base 71 on the outer peripheral side that is attached to the housing 21, a seal portion 72 that directly contacts the sleeve 60, and a seal portion 72 that is biased toward the axis. It has an annular spring 73.

The seal base 71 includes an outer circumferential surface 71a that is in contact with the inner circumferential surface of the opening of the housing 21, and an end surface 71b that extends in the axial direction of the oil seal 70 from the inside of the outer circumferential surface 71a in the vehicle width direction.

The seal portion 72 includes a tongue-shaped dust lip 72a extending further in the axial direction from the tip of the end surface 71b of the seal base 71, and a mountain-shaped convex convex toward the axial center inside the dust lip 72a in the vehicle width direction. and a main lip 72b formed in the main lip 72b. A groove having a semicircular cross section is formed in the circumferential direction on the outer peripheral side of the main lip 72b, and an annular spring 73 is engaged with the groove.

As shown in FIG. 3, in the oil seal 70, the tips of a dust lip 72a and a main lip 72b are in contact with the sleeve 60. The dust lip 72a located on the outside in the vehicle width direction is mainly used to prevent foreign matter such as dust from entering from the outside of the housing 21. The main lip 72b is for preventing oil inside the housing 21 from leaking to the outside.

Further, a dust cover 80 is provided on the inner shaft 5a on the flange portion 53 on the outer peripheral side of the oil seal 70. The dust cover 80 is provided in front of the dust lip 72a to prevent large foreign matter from entering.

The power transmission device consisting of the transmission mechanism 20, the differential mechanism 30, and the drive shaft 5 has the above-described seal structure and transmits the driving force from the motor 10 to the rear wheels 6. Here, FIG. 6 shows an explanatory diagram showing the process of assembling the drive shaft 5 to the differential mechanism 30, and the assembling of the drive shaft 5 to the differential mechanism 30 will be described based on the diagram. In addition, in FIG. 6, illustration of the housing 21 is omitted to make important parts easier to see.

As shown in FIG. 6(a), an inner shaft ball bearing 40 is press-fitted into a bearing press-fitting part 51 in advance in the inner shaft 5a of the drive shaft 5, and a sleeve 60 is fitted into the seal journal part 52. ing. An oil seal 70 is attached to the opening of the housing 21. In this state, the spline portion 50 of the inner shaft 5a is inserted into the side gear 34 of the differential mechanism 30.

At this time, since the outer diameter of the inner shaft ball bearing 40 is smaller than the tips of the dust lip 72a and the main lip 72b of the oil seal 70, interference is difficult to occur. On the other hand, the diameter of the sleeve base 61 of the sleeve 60 is almost the same as the tip of the lip so that it comes into contact with the dust lip 72a and the main lip 72b, but the sleeve tip 62 has a tapered shape so that it can contact the dust lip 72a and the main lip 72b. The main lip 72b is smoothly slid onto the sleeve base 61, resulting in the state shown in FIG. 6(b). Thereafter, the outer shaft 5b is flange-connected to the inner shaft 5a.

In this way, in the vehicle power transmission device of this embodiment, the cylindrical sleeve 60 is fitted to the outer peripheral surface of the seal journal portion 52 of the drive shaft 5, and the sleeve 60 covers the gap for disassembling the ball bearing. There is. By doing this, when inserting the drive shaft 5 into the side gear 34 through the opening of the housing 21, the end surface 52a of the seal journal portion 52 of the drive shaft 5 is prevented from being caught by the dust lip 72a or the main lip 72b of the oil seal 70. Therefore, damage to the oil seal 70 can be prevented.

Further, since the sleeve 60 has a notch 63, when the inner shaft ball bearing 40 is removed from the inner shaft 5a, the claw of the puller tool is removed from the notch 63. It becomes possible to hook the inner shaft ball bearing 40 through the disassembly gap and remove the inner shaft ball bearing 40. In other words, the maintainability of the power transmission device has been maintained.

For example, if the flange portion 53 of the inner shaft 5a has a shape that covers a part of the seal journal portion 52 as shown in FIG. is difficult to do. Through this, as in this embodiment, by using the sleeve 60 as the sliding surface with the oil seal 70, heat treatment and polishing suitable for the sliding surface can be easily performed.

In this way, the power transmission device of this embodiment prevents damage to the oil seal 70 provided at the opening of the housing 21 when assembling the drive shaft 5 without impairing maintainability, and also prevents the oil seal sliding portion from being damaged. The sealing performance can be improved.

This concludes the description of the embodiment of the vehicle power transmission device according to the present invention, but aspects of the present invention are not limited to this embodiment.

Although a pair of rectangular notches 63 are formed in the sleeve 60 of the above embodiment, the number and shape of the notches are not limited to this, and three or more notches may be formed according to the tool used. Alternatively, the shape of the cutout may be changed.

1: Vehicle 4: Drive unit 5: Drive shaft 5a: Inner shaft 5b: Outer shaft 6: Rear wheel 10: Motor 20: Transmission mechanism 21: Housing 30: Differential mechanism 31: Ring gear 32: Differential case 32a: Ball bearing for differential case 33: Pinion gear (differential gear)
34: Side gear (differential gear)
40 : Ball bearing for inner shaft 50 : Spline part 51 : Bearing press-fit part 52 : Seal journal part 52a : End face 53 : Flange part 54 : Flange part 60 : Sleeve 61 : Sleeve base part 62 : Sleeve tip part 63 : Notch part 70 : Oil seal 71: Seal base 71a: Outer surface 71b: End surface 72: Seal portion 72a: Dust lip 72b: Main lip 73: Annular spring 80: Dust cover

Claims (1)

a differential gear that differentially transmits a driving force transmitted from a power source mounted on a vehicle and transmits the driving force to a drive shaft connected to each drive wheel of the vehicle; a differential case that houses the differential gear; A power transmission device for a vehicle, comprising: a housing rotatably supporting the differential case via a first bearing; and an oil seal provided in an opening of the housing and sealing a journal portion of the drive shaft,
The drive shaft is
One end of the drive shaft is engaged with a side gear of the differential gear, and is connected to the differential case via a second bearing that is fitted to the drive shaft with a gap from the end surface of the journal part. Rotatably supported and
It has a cylindrical sleeve fitted to the outer peripheral surface of the journal part,
The power transmission device for a vehicle, wherein the sleeve is formed to cover from the journal portion to the gap, and includes at least two notches.

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