WO2011114768A1

WO2011114768A1 - Speed change transmission unit

Info

Publication number: WO2011114768A1
Application number: PCT/JP2011/050973
Authority: WO
Inventors: 克憲麻生川; 弘之平野
Original assignee: 日産自動車株式会社
Priority date: 2010-03-15
Filing date: 2011-01-20
Publication date: 2011-09-22
Also published as: JP2011190855A; JP5544949B2

Abstract

Rotation of an input axle (8) coaxially fitted to an output axle (9) by way of a bearing (16) is transmitted from a sun gear (11) to a gear part (13a) of a planetary pinion (13), which causes a gear part (13b) of the pinion (13) to roll along the inner circumference of a fixed ring gear (12). Thus, the rotation of the input axle (8) is transmitted to the output axle (9) through a carrier (14). As shown in (b) and (c), the gear part (13a) of the pinion (13) is positioned closer to the output axle (9) than the gear part (13b) of the pinion (13), which is the opposite arrangement to the conventional structure shown in (a). Therefore, the offset between the bearing (16) and the gear part (13a) can be reduced from L3 (conventional structure) to L6 in the case of (b) or 0 in the case of (c). Thus, the amount of radial displacement of the gear part (13a) relative to the sun gear (11) can be reduced and partial engagement between teeth of the sun gear (11) and the gear part (13a) can be reduced when the angle of intersection around the bearing (16) occurs between the input and output axles (8, 9) due to inclination of the output axle (9).

Description

Variable speed transmission unit

The present invention relates to a speed change transmission unit useful for a drive unit for each wheel (commonly referred to as an in-wheel motor unit) used in an electric vehicle capable of traveling by driving wheels by individual electric motors. The present invention relates to a technique for improving the durability of a transmission unit.

As such a transmission gear transmission unit, for example, the one described in Patent Document 1 configured as an in-wheel motor unit has been proposed.
This in-wheel motor unit comprises a planetary gear set type reduction gear having an input shaft and an output shaft that are coaxially opposed and opposed to each other, and an electric motor is coupled to the input shaft on one side in the axial direction of the reduction gear, A wheel is coupled to the output shaft on the other side in the axial direction.

In an electric vehicle having such an in-wheel motor unit for each driving wheel, when the electric motor is driven, the rotation is transmitted to the wheel under deceleration by the speed reducer, and the vehicle can run.

By the way, when the input shaft and output shaft of the reducer that face each other in a coaxial manner are supported rotatably,
The input and output shaft bearing fittings are set by inserting the coaxial butted ends of the input shaft and output shaft so that they can rotate relative to each other, and the input is spaced apart from the input and output shaft bearing fittings in the axial direction. The shaft and the output shaft are respectively supported by the case of the in-wheel motor unit to support the input / output shaft.

JP 2008-037355 A (FIGS. 1 and 7)

However, in such a reduction gear input / output shaft support structure, the coaxial butted ends of the input shaft and output shaft are fitted so as to be relatively rotatable with each other, and the input / output shaft bearing fitting portion is axially extended. Since the portions of the input shaft and the output shaft that are separated from each other are bearing on the unit case, the following problems occur.

That is, when a lateral force (load in the vehicle width direction) is input from the wheel contact surface to the wheel during turning, the output shaft tends to fall with the unit case side bearing portion as a fulcrum.
The tilt of the output shaft due to the wheel lateral force extends to the input shaft through the input / output shaft bearing fitting portion, and the input shaft is tilted in the corresponding direction around the bearing portion on the unit case side. An axis crossing angle is generated between the input shaft and the output shaft at the output shaft bearing fitting portion.

By the way, the input shaft and the output shaft are drive-coupled by the following planetary gear set type speed reducer.
This planetary gear set type reduction gear includes a stepped pinion in which an input shaft meshing gear portion meshing with a sun gear on the input shaft is formed as specified in Patent Document 1, and the stepped pinion is connected to the other gear. A planetary gear whose part meshes with a fixed ring gear and rolls along the inner periphery of the ring gear, and an output shaft is bound to a carrier that rotatably supports a stepped pinion.

For this reason, the stepped pinion protrudes from the output shaft to the input shaft side through the carrier and is bound thereto.
Therefore, the input shaft meshing gear portion of the stepped pinion that meshes with the input shaft (sun gear) is offset from the input / output shaft bearing fitting portion at the coaxial butted end portion of the input shaft and the output shaft toward the input shaft in the axial direction. Inevitable.

As described above, the offset between the input shaft meshing gear portion of the stepped pinion and the input / output shaft bearing fitting portion is caused by the input of the wheel lateral force. Between the amount of radial displacement of the sun gear on the input shaft, which is inevitable when a crossing angle occurs between the shafts, and the amount of radial displacement of the input shaft meshing gear portion formed on the stepped pinion to mesh with the sun gear. Make a difference.

This difference in the amount of radial displacement causes the sun gear on the input shaft and the input shaft meshing gear portion of the stepped pinion to be relatively displaced in the radial direction, causing the gears to come into contact with each other in the meshing portion of the two, and the reduction gear function. There are concerns that it will hinder or reduce its durability, and the concern that the relative rotating parts come into contact with each other cannot be eliminated.

In Patent Document 1, the input / output shaft bearing fitting portion at the coaxial abutting end portion of the input shaft and the output shaft is located at the meshing portion between the sun gear on the input shaft and the input shaft meshing gear portion on the stepped pinion. The offset of the sun gear on the input shaft and the radial displacement of the input shaft meshing gear portion on the stepped pinion meshing with the sun gear A technical idea for reducing the above difference and alleviating the above problem has also been proposed.

However, in the configuration described in Patent Document 1, the input shaft meshing gear portion of the stepped pinion is positioned closer to the input shaft than the other gear portion of the stepped pinion that meshes with the ring gear.
The input / output shaft bearing fitting portion at the coaxial abutting end portion of the input shaft and the output shaft as in the above-described proposed technology, the axis where the meshing portion between the sun gear on the input shaft and the input shaft meshing gear portion in the stepped pinion is located Even if an attempt is made to approach the directional position, the actual offset is that the above-mentioned offset cannot be made as small as desired, and the solution to the above problem cannot be realized fundamentally. .

By reversing the axial position of the input shaft meshing gear portion of the stepped pinion and the other gear portion of the stepped pinion, the present invention makes the input shaft meshing gear portion of the stepped pinion the input shaft and the output shaft. Based on the fact that it can even be positioned at the same axial position as the input / output shaft bearing fitting at the coaxial abutting end, that is, the offset can even be zero, this idea is embodied. It is an object of the present invention to propose a speed change transmission unit that can solve all the above problems.

For this purpose, the speed change transmission unit of the present invention is constituted as follows.
First, to explain the speed change transmission unit that is the premise of the present invention,
The input and output shaft bearing fittings are set by inserting the coaxial butted ends of the input and output shafts so that they can rotate relative to each other. Bearing the shaft and output shaft in the unit case,
The input shaft and the output shaft are drive-coupled by a speed change mechanism including a stepped pinion in which an input shaft meshing gear portion meshing with the input shaft is formed.

The present invention provides such a transmission unit,
The stepped pinion is characterized in that the input shaft meshing gear portion is positioned closer to the output shaft than the other gear portion of the stepped pinion.

According to the speed change transmission unit of the present invention, the input shaft meshing gear portion of the stepped pinion is positioned closer to the output shaft than the other gear portion of the stepped pinion.
Rather than the case where the input shaft meshing gear portion of the stepped pinion is positioned closer to the input shaft than the other gear portion of the stepped pinion as in the past,
The input shaft meshing gear portion of the stepped pinion can be made larger without any structural restrictions, and can be brought closer to the input / output shaft bearing fitting portion at the coaxial butt end portion of the input shaft and the output shaft. Can be small,
It is even possible to set the offset to zero by positioning the input shaft meshing gear portion of the stepped pinion and the input / output shaft bearing fitting portion at the same axial position.

For this reason, the amount of radial displacement of the input shaft meshing gear portion in the stepped pinion, which is inevitable when an axis crossing angle is generated between the input shaft and the output shaft around the input / output shaft bearing fitting portion due to external force, and this input The difference between the amount of displacement in the radial direction of the position on the input shaft with which the shaft meshing gear portion meshes can be made extremely small or zero according to the offset.

Therefore, according to the present invention, the radial displacement of the input shaft meshing gear portion in the stepped pinion, which is inevitable when an axis crossing angle is generated between the input shaft and the output shaft, and the input shaft meshing gear portion on the input shaft meshing with the input shaft. It is possible to cause the radial displacement of the portion in the manner in which both hardly undergo relative displacement in the radial direction.

For this reason, even when the above-mentioned crossing angle is generated between the input shaft and the output shaft, at the meshing portion between the input shaft meshing gear portion of the stepped pinion and the location on the input shaft where the input shaft meshing gear portion meshes The gears do not come into contact with each other, and it is possible to eliminate the concern that the operation of the speed change mechanism will be hindered or that the durability thereof will be reduced. it can.

It is a vertical side view which shows the transmission transmission unit which becomes a 1st Example of this invention comprised as an in-wheel motor unit. It is a principal part expanded detailed sectional view of the in-wheel motor unit in FIG. It is a vertical side view which shows the speed change transmission unit which becomes a 2nd Example of this invention comprised as an in-wheel motor unit. FIG. 4 is an enlarged detailed cross-sectional view of a main part of the in-wheel motor unit in FIG. FIG. 1 is a skeleton diagram showing an outline of the in-wheel motor unit shown in FIGS. 1 and 2 and the in-wheel motor unit shown in FIGS. 3 and 4 in comparison with a conventional in-wheel motor unit. FIG. The skeleton diagram of the unit, (b) is the skeleton diagram of the in-wheel motor unit shown in FIGS. 1 and 2, and (c) is the skeleton diagram of the in-wheel motor unit shown in FIGS. 1 and 2 and the operation of the in-wheel motor unit shown in FIGS. 3 and 4 when the output shaft is tilted compared to the operation of the conventional in-wheel motor unit when the output shaft is tilted. In the figure, (a) is an operation explanatory diagram of a conventional in-wheel motor unit, (b) is an operation explanatory diagram of the in-wheel motor unit shown in FIGS. 1 and 2, and (c) is shown in FIGS. It is operation | movement explanatory drawing of an in-wheel motor unit.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
<Configuration of the first embodiment>
1 and 2 show a transmission transmission unit according to a first embodiment of the present invention configured as an in-wheel motor unit, FIG. 1 is a longitudinal side view thereof, and FIG. 2 is an enlarged detail sectional view of an essential part thereof. .
In these drawings, 1 is a case main body of the in-wheel motor unit, 2 is a rear cover of the case main body 1, and the case main body 1 and the rear cover 2 constitute a unit case 3 of the in-wheel motor unit.

The in-wheel motor unit shown in FIGS. 1 and 2 is configured by housing an electric motor 4 and a planetary gear set type reduction gear 5 (hereinafter simply referred to as “reduction gear”) in a unit case 3.
The electric motor 4 includes an annular stator 6 fitted and fixed to the inner periphery of the case body 1, and a rotor 7 (output rotation) concentrically provided with a radial gap on the inner periphery of the annular stator 6. Element).

The speed reducer 5 corresponds to the speed change mechanism in the present invention, and is input shaft 8 and output shaft 9 which are coaxially opposed to each other, a sun gear 11, and the sun gear 11 shifted in the axial direction away from the output shaft 9. A fixed ring gear 12 arranged concentrically, a stepped planetary pinion (stepped pinion) 13 that meshes with the sun gear 11 and the ring gear 12, and a carrier 14 that rotatably supports the stepped planetary pinion 13.

The input shaft 8 includes the sun gear 11 integrally formed at the inner end close to the output shaft 9, and extends the input shaft 8 backward from the sun gear 11 toward the rear cover 2.
The output shaft 9 extends in the opposite direction (forward) from the speed reducer 5 and protrudes from the front end (right side in the figure) opening of the case body 1, and a wheel 15 is coupled to the output shaft 9 at the protruding portion as described later. To do.

The input shaft 8 and the output shaft 9 are fitted with input / output shaft bearings by inserting both ends of the coaxial butted ends so as to be relatively rotatable with each other, and interposing a bearing 16 enabling a roller bearing between the two. Set the joint.
A bearing 17 enabling a ball bearing and a bearing 18 allowing a double-row angular bearing are respectively provided at positions of the input shaft 8 and the output shaft 9 that are axially separated from the bearing 16 constituting the input / output shaft bearing fitting portion. The unit case 3 is bearing.

The bearing 18 is interposed between the inner periphery of the end lid 19 that closes the front end opening of the case body 1 and the outer periphery of the wheel hub 21 that is fitted to the protruding portion of the output shaft 9 protruding from the front end opening of the case body 1. Let

In the electric motor 4, the rotor 7 is coupled to the input shaft 8, and this coupling position is set as an axial position between the speed reducer 5 and the bearing 17.

The ring gear 12 is fixed in rotation in the front end opening of the case body 1 and prevented from coming off, and a stepped planetary pinion 13 is engaged with the sun gear 11 on the input shaft 8 (input shaft meshing). Stepped pinion (planetary gear) integrally having a small-diameter gear portion (the other gear portion) 13b that meshes with the gear portion) 13a and the ring gear 12 to roll the stepped planetary pinion 13 along the inner periphery of the ring gear 12. And
The stepped planetary pinion 13 has a large-diameter gear portion (input shaft meshing gear portion) 13 a located on the side close to the output shaft 9 and a small-diameter gear portion (the other gear portion) 13 b located on the side far from the output shaft 9. Place it in the direction that you want.

The stepped planetary pinions 13 are arranged as a set of three at equal intervals in the circumferential direction, and the stepped planetary pinions 13 are rotatably supported by a common carrier 14 while maintaining this circumferentially equal interval arrangement.
The carrier 14 is an output rotation member of the speed reducer 5 and is provided at the inner end of the output shaft 9 close to the input shaft 8 so as to be integrated therewith.
For this reason, the carrier 14 and the stepped planetary pinion 13 project from the output shaft 9 toward the input shaft 8 and are bonded to the output shaft 9.

Next, how to connect the wheels 15 to the output shaft 9 will be described in detail.
A brake disc 22 is provided concentrically with the wheel hub 21, and a plurality of wheel bolts 23 are implanted so as to penetrate the wheel hub 21 and the brake disc 22 and protrude in the axial direction.
When the wheel 15 is attached, the wheel disk is brought into close contact with the side surface of the brake disk 22 so that the wheel bolt 23 penetrates into the bolt hole formed in the wheel disk, and in this state, the wheel nut 24 is tightened and screwed. By doing so, the wheel 15 is attached to the output shaft 9.

<Operation of the first embodiment>
When the stator 6 of the electric motor 4 is energized, the rotor 7 of the electric motor 4 is rotationally driven by the electromagnetic force from now on, and this rotational driving force is transmitted to the sun gear 11 of the speed reducer 5 via the input shaft 8.
As a result, the sun gear 11 rotates the stepped planetary pinion 13 via the large-diameter gear portion 13a. At this time, since the fixed ring gear 12 functions as a reaction force receiver, the stepped planetary pinion 13 includes the small-diameter gear portion 13b. Performs a planetary motion that rolls along the ring gear 12.
The planetary motion of the stepped planetary pinion 13 is transmitted to the output shaft 9 through the carrier 14 and rotates the output shaft 9 in the same direction as the input shaft 8.

Due to the above transmission operation, the reduction gear 5 decelerates the rotation from the electric motor 4 to the input shaft 8 at a ratio determined by the number of teeth of the sun gear 11 and the number of teeth of the ring gear 12 and transmits it to the output shaft 9.
The rotation to the output shaft 9 is transmitted to the wheel 15 via the wheel hub 21 and the wheel bolt 23 coupled to the output shaft 9, so that the vehicle can run.
In braking the vehicle, the intended purpose can be achieved by friction-braking the wheel 15 by clamping the brake disc 22 with the brake pad 25 from both sides in the axial direction.

<Effect of the first embodiment>
In the first embodiment shown in FIGS. 1 and 2, the stepped planetary pinion 13, which is the main part of the speed reducer 5 that drives and connects the input shaft 8 and the output shaft 9, meshes with the sun gear 11 on the input shaft 8. Since the large-diameter gear portion (input shaft meshing gear portion) 13a is positioned closer to the output shaft 9 than the other small-diameter gear portion 13b of the stepped planetary pinion 13, the following effects can be obtained.

The transmission transmission unit of the first embodiment is as shown in FIG. 5 (b) when its configuration is shown by a skeleton diagram. FIG. 5 (a) is a comparative diagram for explaining the effect of the first embodiment. Therefore, it is the skeleton which showed roughly the speed change transmission unit of patent documents 1. FIG.
In FIG. 5 (a), for the sake of convenience, parts that function in the same manner as in the first embodiment are indicated by the same reference numerals, and the transmission transmission unit described in Patent Document 1 will be schematically described below using this figure.

As shown in FIG. 5A, the speed change transmission unit described in Patent Document 1 includes an input shaft 8 and an output shaft 9 that are coaxially butted, and the coaxial butted ends of the input and

output shafts

8 and 9 are bearing to each other. 16 is fitted so as to be relatively rotatable.
Further, the input shaft 8 and the output shaft 9 are supported on the unit case 3 by

bearings

17 and 18 at locations separated from the bearing 16 in the axial direction.

Between the input shaft 8 and the output shaft 9, a stepped planetary pinion 13 in which a large diameter gear portion 13a meshing with the sun gear 11 on the input shaft 8 and a small diameter gear portion 13b meshing with the fixed ring gear 12 is formed, Driven and coupled by a speed reduction mechanism 5 comprising a carrier 14 coupled to an output shaft 9.
In the stepped planetary pinion 13, the large-diameter gear portion 13 a that meshes with the sun gear 11 on the input shaft 8 is farther from the output shaft 9 than the small-diameter gear portion 13 b that meshes with the fixed ring gear 12 (closer to the input shaft 8. Side).

As shown by L1, L2, L3, L4, and L5 in FIG. 5, when the axial span between the parts is the same, the conventional transmission gear transmission unit shown in FIG. 5 (a) and FIG. The transmission transmission unit of the first embodiment shown is compared.
In the conventional speed change transmission unit shown in FIG. 5A, the output shaft 9 has the unit case side bearing portion 18 as a fulcrum by the lateral force (load in the vehicle width direction) from the wheel contact surface to the wheel. As shown in a), the input shaft 8 is tilted in the corresponding direction around the unit case side bearing portion 17 through the bearing 16 as shown in FIG. When the axis crossing angle θ1 is generated between the axes 9,
A radial relative displacement amount X1 between the large-diameter gear portion 13a of the stepped planetary pinion 13 coupled to the output shaft 9 via the carrier 14 and the sun gear 11 on the input shaft 8 with which the large-diameter gear portion 13a meshes is determined by the large-diameter gear. It becomes considerably large according to the offset L3 (see FIG. 5) between the portion 13a and the bearing 16.

For this reason, in the meshing portion between the large-diameter gear portion 13a of the stepped planetary pinion 13 and the sun gear 11 on the input shaft 8, a single contact of the gear is caused, and the operation of the speed reducer 5 is hindered. There is a concern that the durability will be lowered, and the concern that the relative rotating parts come into contact with each other cannot be eliminated.

Since the above problem is caused by the size of the offset L3 (see FIG. 5) between the large-diameter gear portion 13a and the bearing 16,
The bearing 16 that forms the input / output shaft bearing fitting portion is moved closer to the axial position where the sun gear 11 on the input shaft 8 and the large-diameter gear portion 13a of the stepped planetary pinion 13 mesh with each other to reduce the offset L3. It is also possible.

However, in the conventional transmission unit, the large-diameter gear portion 13a of the stepped planetary pinion 13 is positioned closer to the input shaft than the small-diameter gear portion 13b of the stepped planetary pinion 13 that meshes with the ring gear 12.
Even if it is attempted to bring the bearing 16 closer to the axial position where the sun gear 11 on the input shaft 8 and the large-diameter gear portion 13a of the stepped planetary pinion 13 mesh with each other as described above, there is a structural limitation and the offset described above. In reality, it cannot be made as small as desired, and the problem cannot be fundamentally solved.

On the other hand, in the speed change transmission unit of the first embodiment whose outline is shown in FIG. 5B, the large-diameter gear portion 13a that is the input shaft meshing gear portion of the stepped planetary pinion 13 is replaced with the stepped planetary. Because it is positioned closer to the output shaft 9 than the small-diameter gear portion 13b that is the other gear portion of the pinion 13,
As is clear from the comparison with FIG. 5A, the large-diameter gear portion 13a of the stepped planetary pinion 13 is made larger without any structural restrictions (for example, the position of the bearing 16 remains unchanged). And the axial offset of the large-diameter gear portion 13a with respect to the bearing 16 is indicated by L6 {= L3- (L5-L2)} in FIG. Can be made smaller.

As shown in FIG. 6B, when the offset between the bearing 16 and the large-diameter gear portion 13a is reduced, the same axis crossing angle θ1 as that in FIG. As you can see,
The radial relative displacement amount X2 between the large-diameter gear portion 13a of the stepped planetary pinion 13 coupled to the output shaft 9 via the carrier 14 and the sun gear 11 on the input shaft 8 with which the large-diameter gear portion 13a meshes is determined by the large-diameter gear. It becomes extremely small according to the offset L6 (see FIG. 5) between the portion 13a and the bearing 16.

For this reason, in the first embodiment, the gears 13a of the stepped planetary pinion 13 and the sun gear 11 on the input shaft 8 are hardly brought into contact with each other, and the reduction gear 5 is not caused. It is possible to eliminate the concern that the operation will be hindered or that the durability thereof will be reduced, and it is possible to surely eliminate the concern that the relative rotating parts come into contact with each other.
Therefore, there is no need to worry about these concerns, and an additional effect that the degree of design freedom is increased accordingly.

<Configuration of Second Embodiment>
3 and 4 show the speed change transmission unit according to the second embodiment of the present invention configured as an in-wheel motor unit as in the first embodiment, FIG. 3 is a longitudinal side view thereof, and FIG. It is an enlarged detailed sectional view.
In these drawings, parts that function in the same manner as in FIGS. 1 and 2 are denoted by the same reference numerals, and here, only the parts different from the first embodiment shown in FIGS. Avoided duplicating explanations of various components.

In the present embodiment, the large diameter gear portion 13a that is the input shaft meshing gear portion of the stepped planetary pinion 13 and the bearing 16 that is the input / output shaft bearing fitting portion are positioned at the same axial direction position, and the large diameter The offset between the gear portion 13a and the bearing 16 is zero.

Therefore, in this embodiment, a bearing hole 8a is formed concentrically at the end face of the inner end portion of the input shaft 8 on which the sun gear 11 is formed, and the bearing hole 8a is formed on the inner end face of the input shaft 8. To a hole having a depth from at least to the inner periphery of the sun gear 11.
A bearing projection 9 a is provided concentrically on the inner end surface of the output shaft 9, and the bearing projection 9 a has a length that penetrates at least into the bearing hole 8 a of the input shaft 8.

Thus, an annular gap is formed between the bearing hole 8a of the input shaft 8 and the bearing projection 9a of the output shaft 9, and the bearing 16 is fitted into the annular gap, so that the input / output shaft bearing fitting portion is provided. Constitute.
In addition, when the sun gear 11 and the large-diameter gear portion 13a mesh with each other, the bearing 16 is fitted at substantially the same axial position.

<Operational effects of the second embodiment>
Also in the second embodiment shown in FIGS. 3 and 4 described above, the rotational driving force of the electric motor 4 (rotor 7) passes through the input shaft 8, the sun gear 11 of the speed reducer 5, the stepped planetary pinion 13, and the output shaft 9 in this order. Can be transmitted to the wheels 15 to drive the vehicle.

Further, the large-diameter gear portion 13 a of the stepped planetary pinion 13 that meshes with the sun gear 11 on the input shaft 8 is closer to the output shaft 9 than the small-diameter gear portion 13 b of the stepped planetary pinion 13 that meshes with the fixed ring gear 12. Therefore, the same effect as in the first embodiment can be achieved as it is.

In the second embodiment, since the bearing 16 constituting the input / output shaft bearing fitting portion is disposed at substantially the same axial position when the sun gear 11 and the large-diameter gear portion 13a are engaged, the following effects are achieved. be able to.
The structure of the speed change transmission unit of the second embodiment is as shown in FIG. 5 (c) when its structure is shown by a skeleton diagram. The speed change transmission unit shown in this figure is also for convenience of comparison with the first embodiment. The specifications are the same as in FIG.

5 (c), the speed change transmission unit of the second embodiment is configured so that the bearing 16 constituting the input / output shaft bearing fitting portion has an axis substantially the same as the meshing position of the sun gear 11 and the large diameter gear portion 13a. To position it in the direction position,
In FIG. 6B, the input shaft 8 is moved as shown by a two-dot chain line 8≡ as shown in FIG. 6C.

For this reason, the axial offset of the large-diameter gear portion 13a with respect to the bearing 16 is as shown by L6 in FIGS. 5B and 6B in the first embodiment, whereas FIG. ) And FIG. 6C, it can be close to 0 without limitation.
FIG. 6C shows a phenomenon when the output shaft 9 is inclined by the same angle as that in FIGS. 6A and 6B and an axis crossing angle θ2 is generated between the input shaft 8 and the input shaft 8 for convenience of comparison. Show.

In the second embodiment, since the offset of the large-diameter gear portion 13a with respect to the bearing 16 can be made substantially zero as described above,
The radial relative displacement amount between the large-diameter gear portion 13a of the stepped planetary pinion 13 coupled to the output shaft 9 via the carrier 14 and the sun gear 11 on the input shaft 8 with which it meshes is shown in the first embodiment. In FIG. 6 (b), it is as indicated by X2, but it can be hardly caused by the offset 0 between the large-diameter gear portion 13a and the bearing 16.

Therefore, it is possible to surely avoid the occurrence of gear hitting at the meshing portion between the large-diameter gear portion 13 a of the stepped planetary pinion 13 and the sun gear 11 on the input shaft 8. It is possible to almost completely eliminate the concern that the trouble will be caused or the durability thereof will be reduced, and it is also possible to almost completely eliminate the concern that the relative rotating parts come into contact with each other.
Therefore, there is no need to worry about these concerns, and the degree of design freedom is further increased as compared with the first embodiment.

<Other examples>
In each of the above-described embodiments, the speed change transmission unit is configured as an in-wheel motor unit of an electric vehicle.
Needless to say, the speed change transmission unit of the present invention is not limited to the in-wheel motor unit, and can be applied to any industrial transmission unit.

In each of the above-described embodiments, the case where the planetary gear set type reduction gear 5 is used as the speed change mechanism in the speed change transmission unit has been described.
The speed change mechanism in the speed change transmission unit is not limited to this, and any type of speed change mechanism (including a speed increasing mechanism) including the stepped planetary pinion 13 can be used. In this case as well, the idea of the present invention is used. Of course, the same effect can be obtained by applying.

Claims

The input and output shaft bearing fittings are set by inserting the coaxial butted ends of the input and output shafts so that they can rotate relative to each other. Bearing the shaft and output shaft in the unit case,
In the transmission transmission unit that is driven and coupled between the input shaft and the output shaft by a transmission mechanism including a stepped pinion in which an input shaft meshing gear portion that meshes with the input shaft is formed.
A transmission transmission unit, wherein the input shaft meshing gear portion of the stepped pinion is positioned closer to the output shaft than the other gear portion of the stepped pinion.
The transmission unit according to claim 1,
The input and output shaft coaxial fitting ends of the input shaft and the output shaft are mutually connected so that the input / output shaft bearing fitting portion is positioned on the inner periphery of the meshing portion between the input shaft meshing gear portion and the input shaft of the stepped pinion. A variable speed transmission unit characterized by being inserted so as to be relatively rotatable.
The transmission unit according to claim 1 or 2,
An output rotating element of an electric motor is coupled to the input shaft;
A wheel is coupled to the output shaft;
The stepped pinion is a planetary gear that the other gear portion meshes with a fixed ring gear and rolls along the inner periphery of the ring gear,
By binding the output shaft to a carrier that rotatably supports the stepped pinion,
A transmission transmission unit characterized by being configured as an in-wheel motor unit.