JP2021055739A - Drive device for vehicle - Google Patents

Abstract

To provide a drive device for a vehicle capable of properly supplying a lubricant in high rotation of a motor in view point of energy loss in a system.SOLUTION: A drive unit 5 is provided with a lubricant storage portion including: a lubricant storage chamber 45 formed by an inner wall 21a of a case body 21 of a speed reduction mechanism 20 and a hollow inner wall 44 of an input shaft 22 at a bearing supporting portion 41 side, and a supply passage 46 for supplying the lubricant scraped up from a plurality of gears to the lubricant storage chamber 45 in the case body 21, in the input shaft 22 of the speed reduction mechanism 20, and the hollow passage 43 communicates the lubricant storage chamber 45 with a spline engagement input portion 42 so that the lubricant is supplied to the spline engagement input portion 42 in a case when a prescribed amount of lubricant is stored in the lubricant storage chamber 45.SELECTED DRAWING: Figure 3

Description

The present invention relates to a vehicle drive device.

In a vehicle such as an electric vehicle whose drive source is a motor, a vehicle drive device having a motor and a power transmission mechanism composed of a plurality of gears and capable of transmitting the driving force of the motor to a differential gear to which the drive wheels are connected is provided. It is known (see Patent Document 1).

In such a vehicle drive device, the output shaft of the motor and the input gear of the power transmission mechanism are coupled by spline engagement from the viewpoint of weight reduction and miniaturization.

Such a spline engaging portion has a problem that the spline engaging portion wears when the supply of lubricating oil is insufficient. To solve this problem, for example, Patent Document 2 proposes a structure in which a lubricating oil pool is formed at a spline engaging portion so that lubrication can be performed at all times.

International Publication No. 2014/148410 Japanese Unexamined Patent Publication No. 2004-360726

However, when the lubricating oil pool is provided in the spline engaging portion, the lubricating oil may be excessively supplied at the time of low speed rotation of the motor. In a system in which lubricating oil is supplied to the spline engaging portion even at low speed rotation of the motor, energy loss becomes large. Therefore, it is desirable to be able to appropriately supply lubricating oil at high rotation speed of the motor where the spline engaging portion is easily worn.

From the above, the problem to be solved in the present application is to provide a vehicle drive device capable of appropriately supplying lubricating oil at high rotation speed of the motor from the viewpoint of energy loss in the system.

The present invention has been made to solve such a problem, and can be realized as the following aspects or application examples.

The vehicle drive device of the vehicle according to the present application example is a vehicle drive device including a motor mounted on the vehicle and a power transmission unit including a plurality of gears for transmitting the drive torque of the motor to the wheels of the vehicle. A case body that accommodates the power transmission unit, a shaft that constitutes the power transmission unit, a bearing support portion that is bearing-supported by the case body on one side, and a rotational output shaft of the motor on the other side. An input shaft including a spline engaging portion that engages with the spline, a hollow path that communicates the bearing support portion and the spline engaging portion inside the shaft, and the bearing support portion side of the input shaft. A lubricating oil storage chamber formed by the inner wall of the case body and the hollow inner wall of the input shaft, and a supply path for supplying the lubricating oil scraped up from the plurality of gears in the case body to the lubricating oil storage chamber. The hollow path includes the lubricating oil storage portion provided with the lubricating oil so that the lubricating oil is supplied to the spline engaging portion when a predetermined amount of the lubricating oil is stored in the lubricating oil storage chamber. It is characterized in that the storage chamber and the spline engaging portion are communicated with each other.

That is, in the lubricating structure of the spline engaging portion using the hollow structure of the input shaft communicating with the spline engaging portion, the gear of the power transmission portion rotates by providing the lubricating oil storage chamber in the middle of the lubricating oil supply path. Then, the lubricating oil is scraped up, and the lubricating oil is supplied to the lubricating oil storage chamber from the supply path. Then, when the motor rotates at high speed, the amount of the lubricating oil scraped up increases, and when the storage level of the lubricating oil supplied to the lubricating oil storage chamber exceeds a certain value, the lubricating oil is supplied to the spline engaging portion. On the other hand, while the motor is rotating at a low speed, the lubricating oil is not supplied to the spline engaging portion, and the lubricating oil is supplied when the motor is rotating at a high speed, which makes it easy for the spline engaging portion to wear. As a result, from the viewpoint of energy loss in the system, lubricating oil can be appropriately supplied to the spline engaging portion at the time of high rotation of the motor.

It is a schematic top view of the electric truck provided with the drive device for a vehicle in one embodiment of the present invention. It is a plan sectional view of the drive device for a vehicle of FIG. (A) A vertical cross-sectional view showing a portion around the input shaft along the line AA of FIG. 2 when the motor is rotating at a low speed, and (b) showing a portion around the input shaft along the line AA of FIG. 2 when the motor is rotating at a high speed. It is a vertical sectional view.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic top view of an electric truck including a vehicle drive device according to an embodiment of the present invention.

As shown in FIG. 1, the vehicle 1 according to the present embodiment is an electric truck including a rudder frame 2, a cab 3, a wheel mechanism 4, and a drive unit 5.

The rudder 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 front-rear direction of the vehicle 1 and are arranged parallel to each other in the vehicle width direction. The plurality of cross members 2b extend in the vehicle width direction and connect a pair of side frames 2a. The rudder frame 2 supports the cab 3, the drive unit 5 (vehicle drive device), 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 portion of the rudder frame 2.

The wheel mechanism 4 has two rear wheels 4a located at the rear of the vehicle and two on each side, and a pair of left and right rear axles 4b as axles of the rear wheels 4a. In the vehicle 1 according to the present embodiment, the driving force is transmitted so that the rear wheels 4a function as the driving wheels, and the vehicle 1 can travel. Although not shown, the wheel mechanism 4 also has front wheels provided at the front portion of the vehicle.

The drive unit 5 includes a motor 10, a reduction mechanism 20 (power transmission unit), and a differential mechanism 30 (power transmission unit). The motor 10 generates the driving force required for traveling of the vehicle 1 by supplying AC power from a battery (not shown) via an inverter. The reduction mechanism 20 includes a plurality of gears, decelerates the rotational driving force input from the motor 10, and outputs the rotational driving force to the differential mechanism 30. The differential mechanism 30 distributes the rotational driving force input from the reduction mechanism 20 to the left and right rear wheels 4a. That is, the drive unit 5 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 rear axle 4b via the reduction mechanism 20 and the differential mechanism 30. As a result, the drive unit 5 rotates the rear wheels 4a via the rear axle 4b to drive the vehicle 1.

Next, FIG. 2 is a plan sectional view of the vehicle drive device of FIG. Hereinafter, the internal structure of the drive unit will be described with reference to the figure.

In the speed reduction mechanism 20, a plurality of gears are housed in the case body 21. Three shafts, an input shaft 22, an intermediate shaft 23, and an output shaft 24, are rotatably supported in the case body 21. The shafts 22, 23, and 24 extend parallel to each other in the vehicle width direction.

One end of the input shaft 22 is connected to the motor output shaft 11 of the motor 10, and a first gear 25a is provided. 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 for the reduction mechanism 20 can be realized. The speed reduction mechanism 20 is configured to be able to convert the rotational driving force of high rotation and low torque input from the motor 10 side into low rotation and high torque and output it.

The differential mechanism 30 transfers the rotational driving force input from the fifth gear 25e, which is the final gear of the reduction gear 20, from the ring gear 31 to the pair of left and right differential output shafts 34 via the pinion gear 32 and the side gear 33. Distribute. Each differential output shaft 34 is connected to the rear axle 4b.

Lubricating oil is sealed inside the speed reduction mechanism 20 and the differential mechanism 30. Here, the amount of lubricating oil sealed in the speed reduction mechanism 20 is adjusted so that the lower end of each gear is below the liquid level from the viewpoint of reducing the rotational resistance of each gear. Therefore, in the normal state, the lubricating oil is not supplied to the input shaft 22 of the speed reduction mechanism 20. However, in the drive unit 5 of the present embodiment, the lubricating oil is scraped up by the rotation of each gear, and each component is lubricated. As a result, in the drive unit 5 of the present embodiment, lubricating oil can be supplied from the inside of the input shaft 22 to the connecting portion between the motor output shaft 11 of the motor 10 and the input shaft 22 of the reduction mechanism 20.

Specifically, FIG. 3A shows a vertical cross-sectional view showing a portion around the input shaft along the line AA of FIG. 2 when the motor is rotating at a low speed, and FIG. 3B shows FIG. 2 when the motor is rotating at a high speed. A vertical cross-sectional view showing a portion around the input shaft along the line AA is shown, and the configuration and operation effect of the input shaft 22 of the speed reduction mechanism 20 will be described below based on the same figure.

The motor 10 has a stator and a rotor (not shown) in the motor case 12, and a motor output shaft 11 connected to the rotor projects from the motor case 12.

On one side (left side in the vehicle width direction) of the input shaft 22 of the speed reduction mechanism 20, a bearing support portion 41 supported by the bearing 40a is formed on the case body 21. Further, on the other side (right side in the vehicle width direction) of the input shaft 22, a spline engagement input portion 42 that spline engages with the spline engagement output portion 11a of the motor output shaft 11 of the motor 10 is formed. In the connecting portion between the input shaft 22 and the motor output shaft 11 which are connected by the spline engagement, the spline engagement input portion 42 of the outer teeth is inserted into the spline engagement output portion 11a of the internal teeth, and the spline The engagement output portion 11a is rotatably supported by the case body 21 via the bearing 40b.

Further, the input shaft 22 is formed with a hollow path 43 that communicates the bearing support portion 41 side and the spline engagement input portion 42 side inside the shaft. The hollow path 43 has a circular tubular shape extending along the axis of the input shaft 22.

Further, in the input shaft 22, a lubricating oil storage chamber 45 is formed on the bearing support portion 41 side mainly by the inner wall 21a of the case body 21 and the hollow inner wall 44 of the input shaft 22. On the upper surface of the lubricating oil storage chamber 45, a supply path 46 for supplying lubricating oil scraped up from a plurality of gears in the case body 21 is formed. A lubricating oil storage portion is formed by the lubricating oil storage chamber 45 and the supply path 46.

Further, the bearing 40a supporting the bearing support portion 41 is provided with a seal member 47 on the surface of the case body 21 facing the inner wall 21a. As a result, it is possible to prevent the lubricating oil stored in the lubricating oil storage chamber 45 from passing through the bearing 40a through the gap between the end surface of the input shaft 22 on the bearing support portion 41 side and the inner wall 21a of the case body 21. ing.

The lubricating oil storage chamber 45 has a diameter larger than that of the hollow path 43, forms a circular tubular shape extending by a predetermined length from the end face on the bearing support portion 41 side along the axis of the input shaft 22, and communicates with the hollow path 43. ing. That is, the hollow path 43 is engaged with the lubricating oil storage chamber 45 so that the lubricating oil is supplied to the spline engagement input unit 42 only when a predetermined amount or more of the lubricating oil is stored in the lubricating oil storage chamber 45. It communicates with the joint input unit 42.

The drive unit 5 having the input shaft 22 configured in this way lubricates the input shaft 22 through the supply path 46 when each gear of the reduction gear 20 rotates and the lubricating oil inside the case body 21 is scraped up. Lubricating oil is stored in the oil storage chamber 45. The lubricating oil storage chamber 45 is sealed with a sealing member 47 or the like, but the stored lubricating oil gradually escapes through a slight gap between the parts.

As shown in FIG. 3A, when the vehicle 1 is traveling at a low speed, that is, when the motor output shaft 11 and the input shaft 22 are rotating at a low speed, the rotation of each gear of the reduction mechanism 20 is also low. The amount of lubricating oil scraped up is also small. Therefore, the amount of lubricating oil supplied to the lubricating oil storage chamber 45 of the input shaft 22 is small, and the lubricating oil is stored to the extent that it does not reach the hollow path 43.

On the other hand, when the speed of the vehicle 1 increases, that is, the rotation of the motor output shaft 11 and the input shaft 22 becomes high speed, the rotation of each gear of the reduction mechanism 20 also becomes high speed, and the amount of the lubricating oil scraped up increases. Therefore, the amount of lubricating oil supplied to the lubricating oil storage chamber 45 of the input shaft 22 also increases, and the amount of storage increases.

Then, as shown in FIG. 3B, the storage level of the lubricating oil in the lubricating oil storage chamber 45 exceeds a certain value, and the stored lubricating oil passes through the hollow path 43 to the spline engagement input portion 42 side. Inflow. As a result, the spline engagement input portion 42 of the input shaft 22 and the spline engagement output portion 11a of the motor output shaft 11 are lubricated.

In this way, the drive unit 5 forms a lubricating oil storage chamber 45 on one side of the input shaft 22, and does not supply the lubricating oil to the spline engaging input portion 42 side when the motor 10 rotates at a low speed, so that the lubricating oil is excessively supplied. Can be suppressed and energy loss can be reduced. In addition, if it is desired to variably control the amount of lubricating oil supplied to the spline engagement input unit 42 regardless of the drive unit 5 according to the present embodiment, a new pump structure or the like is required. Therefore, according to the drive unit 5 according to the present embodiment, it is possible to suppress an increase in unit size and cost. On the other hand, when the motor 10 is rotating at high speed, the spline engaging portion is easily worn, by supplying lubricating oil from the lubricating oil storage chamber 45 to the spline engaging input portion 42 side via the hollow path 43, the spline engaging input portion Wear of 42 and the spline engagement output portion 11a can be suppressed.

As a result, the drive unit 5 according to the present embodiment can appropriately supply lubricating oil when the motor 10 rotates at high speed from the viewpoint of energy loss in the system.

Although the description of the embodiment of the present invention is completed above, the aspect of the present invention is not limited to this embodiment.

For example, in the above embodiment, the hollow path 43 and the lubricating oil storage chamber 45 are formed on the input shaft 22 of the drive unit 5, but the configuration may be applied to the intermediate shaft 23 and the output shaft 24.

1 Vehicle 4 Wheel mechanism 4a Rear wheel 4b Rear axle 5 Drive unit 10 Motor 11 Motor output shaft 11a Spline engagement output part 12 Motor case 20 Deceleration mechanism 21 Case body 21a Inner wall 22 Input shaft 23 Intermediate shaft 24 Output shaft 30 Differential mechanism 40a, 40b Bearing 41 Bearing support 42 Spline engagement input 43 Hollow path 44 Hollow inner wall 45 Lubricating oil storage chamber 46 Supply path 47 Sealing member

Claims (1)

A vehicle drive device including a motor mounted on a vehicle and a power transmission unit including a plurality of gears for transmitting the drive torque of the motor to the wheels of the vehicle.
A case body accommodating the power transmission unit and
A shaft that constitutes the power transmission unit, one is a bearing support portion that is bearing-supported by the case body, and the other is a spline engagement portion that splines engages with the rotational output shaft of the motor, and the bearing support portion. An input shaft comprising a hollow path that communicates the spline engaging portion with the spline engaging portion inside the shaft.
On the bearing support side of the input shaft, the lubricating oil storage chamber formed by the inner wall of the case body and the hollow inner wall of the input shaft, and the lubricating oil scraped up from the plurality of gears in the case body are said to be the same. A lubricating oil storage unit including a supply path for supplying to the lubricating oil storage chamber,
Including
The hollow path connects the lubricating oil storage chamber and the spline engaging portion so that the lubricating oil is supplied to the spline engaging portion when a predetermined amount of lubricating oil is stored in the lubricating oil storage chamber. A vehicle drive device characterized by communication.

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