JP7421369B2 - transaxle - Google Patents

Description

The present invention relates to a transaxle that can reduce rotational resistance experienced by gears.

Conventionally, in a transaxle, oil filled in a housing is scooped up and splashed in order to lubricate gears, shafts, etc. in the housing (for example, Patent Document 1). In the transaxle of Patent Document 1, oil on the differential gear side and oil on the transmission side are shared.

Japanese Patent Application Publication No. 2016-11734

However, in the transaxle as disclosed in Patent Document 1, high viscosity differential oil is used to lubricate the differential gear. Therefore, there is a problem in that the rotational resistance experienced by the gears on the transmission side increases, resulting in poor fuel efficiency and electricity consumption in electric vehicles and the like. On the other hand, when the viscosity of the oil used in the transaxle is reduced, there is a problem in that the differential gear seizes.

Another possibility is to separate the differential chamber where the differential gear is housed from the reduction mechanism chamber where the gears on the transmission side are housed, but this would increase the size of each housing chamber and increase the amount of oil to be injected. be. When the speed reduction mechanism chamber becomes larger, there is a problem in that a large amount of relatively expensive oil such as automatic transmission fluid (also referred to as ATF) must be used, resulting in an increase in cost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a transaxle that can improve fuel efficiency and electricity consumption by reducing rotational resistance due to oil.

(1) A transaxle of the present invention provided to solve the above-mentioned problems includes a transaxle housing, a reduction mechanism that reduces rotational power input from a power source, a differential mechanism, the differential mechanism, and the reduction mechanism. a drive shaft that connects the transaxle housing so as to be capable of transmitting power, and the transaxle housing has a differential chamber in which the differential mechanism is housed, and a deceleration mechanism chamber in which the deceleration mechanism is housed. The differential chamber and the reduction mechanism chamber are separated from each other by an oil seal provided at an axially intermediate portion of the drive shaft.

In the transaxle of the present invention, the differential chamber and the reduction mechanism chamber are separated by an oil seal provided in the axially intermediate portion of the drive shaft, so different oils are injected into the differential chamber and the reduction mechanism chamber. becomes possible. Therefore, the transaxle of the present invention can use different oils suitable for each of the speed reduction mechanism and differential mechanism, such as using high viscosity oil for the differential chamber and low viscosity oil for the speed reduction mechanism chamber. Therefore, according to the transaxle of the present invention, rotational resistance in the reduction mechanism chamber can be reduced. Thereby, fuel efficiency and electricity consumption in the vehicle can be improved.

(2) In the transaxle of the present invention provided to solve the above problems, the drive shaft includes a differential shaft connected to the differential ring gear, and a drive gear shaft connected to the drive gear. The differential shaft and the drive gear shaft are connected in series in the axial direction via a spline fitting part formed by spline fitting, and are rotatably supported by a bearing in the spline fitting part. , the oil seal is arranged at a position adjacent to the spline fitting portion in the axial direction of the drive shaft.

The transaxle of the present invention has a drive shaft in which a spline fitting portion is formed by connecting a differential shaft and a drive gear shaft in series through spline fitting. With such a configuration, twisting between the differential shaft and the drive gear shaft may easily occur in the spline fitting portion. However, in the transaxle of the present invention, since the drive shaft is rotatably supported by a bearing in the spline fitting portion, the influence of torsion between the shafts as described above can be suppressed to a minimum.

Further, the transaxle of the present invention is such that the influence of torsion in the spline fitting portion is eliminated by the bearing, and the oil seal is arranged at a position adjacent to the spline fitting portion in the axial direction of the drive shaft. There is. According to this configuration, it is possible to suppress the influence of torsion between the differential shaft and the drive gear shaft from reaching the oil seal. Therefore, the transaxle of the present invention can suppress deterioration in sealing performance due to twisting of the oil seal, etc., and can suppress the occurrence of oil leaks.

(3) The transaxle of the present invention provided to solve the above problems is characterized in that the differential shaft and the drive gear shaft are each rotatably supported by a plurality of bearings. be.

According to this configuration, the load applied to the bearing can be distributed to a plurality of bearings, so each bearing can be downsized. Thereby, no-load loss torque of the bearing can be reduced. Therefore, fuel efficiency and electricity consumption of the vehicle can be improved. Note that a tapered roller bearing (also referred to as a tapered roller bearing) can be preferably used as the bearing.

(4) In the transaxle of the present invention provided to solve the above-mentioned problems, the differential chamber is injected with oil having a higher viscosity than the reduction mechanism chamber, and the reduction mechanism chamber is filled with oil having a higher viscosity than the reduction mechanism chamber. It is characterized by injecting oil with low viscosity.

According to this configuration, the differential gear and the drive gear can be lubricated with oil having a viscosity suitable for each. That is, the differential gear can be lubricated using a differential oil with a high viscosity, and the drive gear can be lubricated with a low viscosity oil. This allows the drive gear to be lubricated with low viscosity oil such as ATF while preventing the differential gear from seizing. Therefore, fuel efficiency and electricity consumption of the vehicle can be improved.

(5) In the transaxle of the present invention provided to solve the above-mentioned problems, the drive shaft has a constricted portion formed between the differential chamber and the reduction mechanism chamber, and the oil seal , is characterized in that it is arranged so as to be located on the constricted portion.

According to this configuration, it becomes easy to install the oil seal between the reduction mechanism chamber and the differential chamber. Furthermore, since the oil seal can be installed at any position on the constriction, the versatility of the position for partitioning the reduction mechanism chamber and the differential chamber increases, and the degree of freedom in designing the transaxle increases.

(6) The transaxle of the present invention provided to solve the above-mentioned problems makes the differential chamber and the reduction mechanism chamber communicate with each other by removing the oil seal, so that the oil to be injected is shared. It is characterized by making it possible to

According to this configuration, the cost of oil is reduced by removing the oil seal and sharing the oil between the differential chamber and the reduction mechanism chamber with, for example, low-cost differential gear oil (also simply referred to as differential oil). can. As a result, the oil seal can be easily removed, so you can choose whether or not to have an oil seal depending on the application, such as whether the vehicle is cost-oriented or the vehicle is designed to improve fuel efficiency and electricity consumption. It becomes possible. Therefore, since the structure of the transaxle other than the oil seal can be shared, the transaxle can be made more versatile. Therefore, design cost and manufacturing cost can be reduced.

According to the present invention, it is possible to provide a transaxle that can improve fuel efficiency and electricity consumption by reducing rotational resistance due to oil.

1 is a schematic diagram of a transaxle according to a first embodiment of the present invention viewed from a planar direction. FIG. 1 is a conceptual diagram of a transaxle of the present invention viewed from the side. FIG. 2 is a cross-sectional view taken along the line AA in FIG. 1; FIG. 2 is a schematic diagram of the transaxle of the present invention, viewed from a plane direction, with an oil seal removed. FIG. 2 is a conceptual side view of the transaxle of the present invention with an oil seal removed.

Below, one embodiment of the transaxle 10 of the present invention will be described in detail with reference to FIGS. 1 to 3. Note that the shapes are drawn in a simplified manner for ease of explanation.

As shown in FIG. 1, the transaxle 10 is mounted on a vehicle 1. A motor 2 (also referred to as a power source) and the like are connected to the transaxle 10 on the rear side. The transaxle 10 and the motor 2 constitute a drive device 3 of the vehicle 1.

The drive device 3 is disposed, for example, on the front side of the vehicle 1, and can transmit the rotational power output from the motor 2 to the pair of drive shafts 82 via the speed reduction mechanism 50. Each drive shaft 82 is connected to a pair of drive wheels 80, and the vehicle 1 travels by driving the drive wheels 80 via the drive shaft 82. The motor 2 is a motor generator that has a function of generating power in addition to a motor function of outputting power for driving the vehicle toward the drive wheels 80 .

As shown in FIG. 1, the transaxle 10 includes a transaxle housing 20, a speed reduction mechanism 50, a drive shaft 60, a differential mechanism 70, and the like. The speed reduction mechanism 50, the drive shaft 60, and the differential mechanism 70 are housed within the transaxle housing 20. The transaxle housing 20 also includes a reduction mechanism chamber 51 that accommodates the reduction mechanism 50 and a differential chamber 71 that accommodates the differential mechanism 70. In this embodiment, a vertical type motor in which the motor 2 and the transaxle 10 are arranged in series will be described as an example.

The speed reduction mechanism 50 is housed inside a speed reduction mechanism chamber 51 formed on the rear side within the transaxle housing 20. Further, the speed reduction mechanism 50 includes an input gear 52, a drive gear 53 as an output side gear, a differential ring gear 73, and the like.

As shown in FIG. 1, the input gear 52 is formed around the axis L1 at an intermediate portion of the input gear shaft 52a. The input gear shaft 52a is provided along the front-rear direction (left-right direction in the figure) within the reduction mechanism chamber 51. Both ends of the input gear shaft 52a are rotatably supported by support walls within the reduction mechanism chamber 51. Further, a motor shaft (not shown) of the motor 2 is connected to the rear end side of the input gear shaft 52a. Therefore, the power of the motor 2 is input to the input gear shaft 52a.

The drive gear 53 is formed around the axis L2 at an intermediate portion of the drive gear shaft 53a. The drive gear shaft 53a is arranged parallel to the input gear shaft 52a. The rear end side of the drive gear shaft 53a is rotatably supported by the support wall of the reduction mechanism chamber 51. Further, a spline fitting portion 56, which will be described later, is formed on the front end side of the drive gear shaft 53a, and the spline fitting portion 56 is rotatably supported by a support wall on the front end side of the reduction mechanism chamber 51. The drive shaft 60 is formed by connecting a drive gear shaft 53a and a differential shaft 74a, which will be described later. Further, the input gear 52 and the drive gear 53 are engaged with each other, and the rotational power of the motor 2 is transmitted from the input gear 52 to the drive gear 53.

FIG. 2 is a conceptual side view of the transaxle 10 of the present invention. As shown in FIG. 2, a first oil 62a such as low-viscosity ATF is injected into the reduction mechanism chamber 51 so as to lubricate the drive gear 53 and the like housed therein. Although details will be described later, in this embodiment, the reduction mechanism chamber 51 and the differential chamber 71 are partitioned off by the oil seal 61, and the first oil 62a is prevented from flowing into the differential chamber 71 side. ing.

As shown in FIG. 1, the differential mechanism 70 is housed inside a differential chamber 71 formed on the front side of the speed reduction mechanism chamber 51. Further, the differential mechanism 70 includes a differential shaft 74a, a differential gear mechanism 72, a differential ring gear 73, and the like.

An intermediate gear 74 is provided on the front end side of the differential shaft 74a. The differential shaft 74a is provided coaxially with the axis L2 of the drive gear shaft 53a, and is connected to the front end of the drive gear shaft 53a by spline fitting. As a result, a spline fitting portion 56 is formed on the rear end side of the differential shaft 74a. Further, the differential shaft 74a has a constricted portion 74b formed with a small diameter between the intermediate gear 74 and the spline fitting portion 56. Further, the front end side and the intermediate portion of the differential shaft 74a are rotatably supported by tapered roller bearings 55 (also referred to as tapered roller bearings 55). In this way, by rotatably supporting one or both of the differential shaft 74a and the drive gear shaft 53a connected by spline fitting with the tapered roller bearing 55, the twisting force generated in the spline fitting portion 56 can be reduced. can be resolved. Thereby, the strength of the spline fitting portion 56 can be maintained, and damage to the differential shaft 74a and the drive gear shaft 53a can also be suppressed.

As described above, by supporting the drive shaft 60 with the plurality of tapered roller bearings 55 and the plurality of bearings 57, the load supporting the drive shaft 60 can be dispersed. Therefore, the tapered roller bearing 55 and the bearing 57 can be downsized, and the loss torque of these bearings when no load is applied can be reduced. Thereby, the fuel efficiency and electricity consumption of the vehicle 1 can be improved.

The intermediate gear 74 meshes with a differential ring gear 73 of the differential gear mechanism 72. Thereby, the deceleration mechanism 50 can decelerate the output of the motor 2 and transmit it to the differential gear mechanism 72.

The differential gear mechanism 72 includes a differential ring gear 73. Further, a pair of drive shafts 82 are supported in the differential gear mechanism 72 so as to be rotatable around an axis orthogonal to the drive shaft 60. A drive wheel 80 is connected to the drive shaft 82 . The differential gear mechanism 72 distributes and transmits the power of the motor 2 transmitted to the differential ring gear 73 to each of the pair of drive wheels 80 . Further, when a rotation difference occurs between the pair of drive wheels 80, the differential gear mechanism 72 transmits power while absorbing the rotation difference.

The spline fitting portion 56 is rotatably supported between the reduction mechanism chamber 51 and the differential chamber 71. Further, an oil seal 61 is fitted into the outer peripheral portion of the spline fitting portion 56. The oil seal 61 is located at an axially intermediate portion of the drive shaft 60. Note that the oil seal 61 may be provided so as to be located on the constricted portion 74b formed in the drive shaft 60. Thereby, the position partitioned by the oil seal 61 can be easily changed, so the versatility of the transaxle 10 can be increased, and the degree of freedom in design can be increased.

Further, the spline fitting portion 56 integrates the differential shaft 74a and the drive gear shaft 53a to form a drive shaft 60. The drive shaft 60 can transmit the rotation of the input gear shaft 52a to the drive wheels 80 via the reduction gear mechanism 50, the differential gear mechanism 72, and the drive shaft 82.

FIG. 3 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 3, the oil seal 61 is formed in a circular donut shape and partitions between the spline fitting portion 56 and the inner wall of the transaxle housing 20. Thereby, the differential chamber 71 and the reduction mechanism chamber 51 are separated via the oil seal 61. Here, the oil seal 61 can be made of, for example, nitrile rubber, fluororubber, silicone rubber, or the like. Note that it is desirable that the oil seal 61 be oil resistant to the oil 62 used.

As shown in FIG. 2, the differential gear chamber 71 is filled with a second oil 62b, such as a relatively high-viscosity differential oil, for lubricating the differential gear mechanism 72, the differential shaft 74a, and the like. The second oil 62b is prevented from flowing into the reduction mechanism chamber 51 by the oil seal 61. Note that the oil seal 61 is allowed to rotate while contacting the inner wall of the transaxle housing 20.

Further, a breather 63 is provided in the upper part of each of the reduction mechanism chamber 51 and the differential chamber 71. The breather 63 can communicate with the outside and release the internal pressure when the internal pressure of the speed reduction mechanism chamber 51 and the differential chamber 71 increases. Note that the number and installation positions of the breathers 63 can be changed as appropriate.

As described above, in this embodiment, the reduction mechanism chamber 51 and the differential chamber 71 are separated by the oil seal 61, and different oils can be stored in the reduction mechanism chamber 51 and the differential chamber 71. . Therefore, the first oil 62a with low viscosity is used in areas where rotational resistance is desired to be reduced, such as the reduction mechanism chamber 51, and the second oil 62b with high viscosity is used in areas where a large load is applied to the gears, such as the differential chamber 71. can be used. Thereby, the rotational resistance of the transaxle 10 can be reduced, so that the fuel efficiency and electricity consumption of the vehicle 1 can be improved. Further, since the high viscosity second oil 62b can be used on the differential chamber 71 side, seizure of the differential mechanism 70 can be prevented.

The above is one embodiment of the transaxle 10 of the present invention. Next, in the transaxle of the present invention, the state when the oil seal is removed will be described in detail below based on FIGS. 4 and 5.

4 and 5 illustrate the transaxle 10 of the present invention with the oil seal 61 removed. As illustrated, the transaxle 10 of the present invention can be operated without changing other structures even when the oil seal 61 is removed. That is, this usage example differs from the above-described embodiment in that the oil seal 61 is removed so that the reduction mechanism chamber 51 and the differential chamber 71 communicate with each other. Further, this embodiment differs from the above embodiment in that the same oil 62 is injected into the reduction mechanism chamber 51 and the differential chamber 71 by removing the oil seal 61. The other configurations are the same as those in the first embodiment, so detailed explanations will be omitted. Furthermore, it should be noted that the same reference numerals are used for the same members in the drawings.

When the oil seal 61 is removed and used, it is desirable to use a low-cost oil 62 such as differential oil in the reduction mechanism chamber 51 and the differential chamber 71, for example. By injecting the low-cost oil 62 in this manner, the cost of the vehicle 1 can be reduced.

Further, by adopting a structure in which the reduction mechanism chamber 51 and the differential chamber 71 are separated by the oil seal 61, the structure of the transaxle 10 can be easily changed by removing the oil seal 61 depending on the intended use of the vehicle 1. Can be done. As a result, the transaxle 10 can be made more versatile, so the design of the vehicle 1 can be shared. Therefore, design cost and manufacturing cost can be reduced.

Although the embodiments of the transaxle 10 of the present invention have been described above, the present invention is not limited to the embodiments described above, and appropriate changes can be made within the scope of the invention.

In this embodiment, the deceleration mechanism chamber 51 and the differential chamber 71 are partitioned and separated via the oil seal 61, but the shape and material of the oil seal 61 are not limited to the above embodiments. . The shape of the oil seal 61 can be changed as appropriate depending on the shape of the inner wall of the transaxle housing 20 and the shape of the drive shaft 60.

Various shapes can be adopted depending on the shapes and structures of the input gear 52, the drive gear 53, and the differential gear mechanism 72 that accommodate the transaxle housing 20, the speed reduction mechanism chamber 51, and the differential gear chamber 71. Further, the arrangement of the speed reduction mechanism chamber 51 and the differential gear chamber 71, and the arrangement of the input gear 52, drive gear 53, and differential gear mechanism 72 can also be changed as appropriate within the scope of the invention.

Further, in the present embodiment, the drive shaft 60 connects the drive gear shaft 53a and the differential shaft 74a by spline fitting, but the transaxle 10 of the present invention is not limited to this, and the drive shaft 60 is integrally connected to the drive gear shaft 53a and the differential shaft 74a by spline fitting. It may be formed as follows. Further, the drive shaft 60 may be formed by connecting two or more shafts. Further, the drive gear shaft 53a and the differential shaft 74a are connected not only by spline fitting, but also by various connection methods.

In this embodiment, the oil seal 61 is arranged at a position adjacent to the spline fitting portion 56 in the axial direction of the drive gear shaft 53a, but the oil seal 61 is located between the reduction mechanism chamber 51 and the differential chamber 71. It can be placed in various positions as long as it can separate the two. The oil seal 61 may be arranged, for example, on the constricted portion 74b of the differential shaft 74a.

In this embodiment, the differential shaft 74a and the drive gear shaft 53a are each rotatably supported by a plurality of bearings, but the number of bearings may be one. Note that it is desirable to use two or more bearings in order to distribute the load applied to the bearings, make the bearings smaller, and thereby reduce torque loss during no-load conditions. Further, when providing the spline fitting portion 56, it is desirable to use a tapered roller bearing 55. By using the tapered roller bearing 55, twisting force at the connection portion of the spline fitting portion 56 can be eliminated. Further, an oil seal 61 may be placed at the position of the bearing 57.

In this embodiment, it is assumed that oil having a higher viscosity than that of the reduction mechanism chamber 51 is injected into the differential chamber 71, and oil having a lower viscosity than that of the differential chamber 71 is injected into the reduction mechanism chamber 51. The oil injected into the reduction mechanism chamber 71 and the reduction mechanism chamber 51 may have an appropriate viscosity depending on the intended use of the vehicle 1. The purpose of use of the vehicle 1 may be, for example, focusing on cost, or focusing on fuel efficiency and electricity consumption. Further, the amount of oil to be injected can also be changed as appropriate.

Furthermore, in this embodiment, by removing the oil seal 61, the differential chamber 71 and the speed reduction mechanism chamber 51 are communicated with each other, so that the oil 62 to be injected is shared. On the other hand, the differential chamber 71 and the speed reduction mechanism chamber 51 may be communicated with each other by not only removing the oil seal 61 but also by shifting its position.

It should be noted that the present invention is not limited to the embodiments and modifications described above, and those skilled in the art will recognize that other embodiments may be made based on the teaching and spirit of the invention without departing from the scope of the claims. It's easy to understand.

INDUSTRIAL APPLICATION This invention can be suitably utilized in various vehicles, such as a gasoline car, a diesel car, a hybrid car, and an electric car, which are equipped with a transaxle. INDUSTRIAL APPLICATION This invention can be suitably utilized in the vehicle which employs a vertical transaxle.

1: Vehicle 2: Motor (power source)
3: Drive device 10: Transaxle 20: Transaxle housing 50: Reduction mechanism 51: Reduction mechanism chamber 53: Drive gear 53a: Drive gear shaft 55: Tapered roller bearing (tapered roller bearing)
56: Spline fitting part 57: Bearing 60: Drive shaft 61: Oil seal 62: Oil 62a: First oil 62b: Second oil 70: Differential mechanism 71: Differential chamber 72: Differential gear mechanism 73: Differential ring gear 74a: Differential shaft 74b: Neck part

Claims (2)

transaxle housing,
a deceleration mechanism that decelerates the rotational power input from the power source;
differential mechanism,
a drive shaft that connects the differential mechanism and the speed reduction mechanism to enable power transmission;
has
The transaxle housing includes:
a differential chamber in which the differential mechanism is housed;
a deceleration mechanism chamber in which the deceleration mechanism is housed;
has inside,
The differential chamber and the speed reduction mechanism chamber are separated via an oil seal provided at an axially intermediate portion of the drive shaft,
The drive shaft is
a differential shaft connected to the differential ring gear and rotatably supported via a tapered roller bearing;
a drive gear shaft connected to the drive gear;
The differential shaft and the drive gear shaft are connected in series in the axial direction via a spline fitting portion formed by spline fitting, and are rotatably supported by a bearing in the spline fitting portion. ,
The transaxle is characterized in that the oil seal is provided on an outer periphery of the spline fitting portion, and is provided between the tapered roller bearing and the bearing, and in the vicinity of the bearing . The drive shaft has a constriction formed between the differential chamber and the reduction mechanism chamber,
The transaxle according to claim 1, wherein the oil seal is arranged so as to be located on the constricted portion.

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