JP2021148195A - Power transmission device - Google Patents

Abstract

To provide a power transmission device capable of preventing generation of foreign sound such as tooth hammering sound in a planetary gear mechanism by torque fluctuation.SOLUTION: In a power transmission device 100 in which a plurality of planetary gear mechanisms PG1, PG2 coaxially disposed, are housed in a housing 1, ring gears r1, r2 of two planetary gear mechanisms PG1, PG2 axially adjacent to each other, are fixed in the housing 1, a spring member 13 bent into a dog leg shape is disposed in a circumferential clearance δ between each of the ring gears r1, r2 of two planetary gear mechanisms PG1, PG2 axially adjacent to each other and the housing 1 in a manner of axially crossing both ring gears r1, r2. Here, the ring gears r1, r2 of two planetary gear mechanisms PG1, PG2 are respectively fixed to the housing 1 by spline-fitting, and the spring members 13 are respectively disposed in a circumferential clearance δ of the fitting portion of the ring gears r1, r2 and the housing 1. The plurality of spring members 13 are arranged at equal angular pitches in a circumferential direction.SELECTED DRAWING: Figure 3

Description

The present invention relates to a power transmission device including a plurality of planetary gear mechanisms arranged coaxially.

For example, a vehicle power transmission device is provided with a deceleration mechanism for decelerating the rotation input to an input shaft from a drive source such as an engine or an electric motor. In order to obtain a high reduction ratio in this deceleration mechanism. In addition, for example, a power transmission device in which a plurality of planetary gear mechanisms are arranged side by side in the axial direction is known.

By the way, each planetary gear mechanism includes a sun gear, a ring gear arranged around the sun gear, a plurality of pinion gears (planetary gears) that revolve around the sun gear while meshing with the sun gear and the ring gear, and these pinion gears. It is configured to include a carrier that rotatably supports the. According to a power transmission device in which two such planetary gear mechanisms are arranged side by side in the axial direction, for example, the rotation of the input shaft rotationally driven by the drive source is decelerated in two stages by the two planetary gear mechanisms. Therefore, a high reduction ratio can be obtained, and the whole can be made compact and compact.

However, in a power transmission device provided with a reduction mechanism in which a plurality of planetary gear mechanisms are arranged side by side in the axial direction, there is a problem that the ring gears cause axial runout at high load and the ring gears collide with the housing to generate an abnormal noise. there is a possibility.

Therefore, in Patent Document 1, a soft elastic body is fixed to the outer periphery of the ring gear, and the impact when the ring gear collides with the housing is absorbed by the elastic deformation of the soft elastic body, so that an abnormal noise caused by the shaft runout of the ring gear is obtained. A muffling device has been proposed that suppresses the occurrence of.

Jikkai Sho 62-080071

However, in the sound deadening device proposed in Patent Document 1, since the soft elastic body is struck and crushed at a high load, the impact absorption effect of the soft elastic body is reduced, and the effect of suppressing abnormal noise is also reduced. There is.

By the way, in a planetary gear mechanism in which a ring gear is fixed to a housing by spline fitting, there is a problem that a rattling noise is generated at a spline fitting portion between the ring gear and the housing due to collision between spline teeth due to torque fluctuation. The muffling device proposed in Patent Document 1 cannot prevent the occurrence of such a rattling noise.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power transmission device capable of preventing generation of abnormal noise such as rattling noise in a planetary gear mechanism due to torque fluctuation.

In order to achieve the above object, the present invention accommodates a plurality of planetary gear mechanisms (PG1, PG2) arranged coaxially in the housing (1), and two planetary gear mechanisms (PG1) adjacent to each other in the axial direction. , PG2) is a power transmission device (100) in which each ring gear (r1, r2) is fixed to the housing (1), and each ring gear (PG1, PG2) of the two planetary gear mechanisms (PG1, PG2) adjacent to each other in the axial direction. A feature is that a bending spring member (13) is arranged in a circumferential gap (δ) between r1, r2) and the housing (1) so as to straddle both ring gears (r1, r2) in the axial direction. do.

Here, the ring gears (r1, r2) of the two planetary gear mechanisms (PG1, PG2) are fixed to the housing (1) by spline fitting, respectively, and these ring gears (r1, r2) and the housing (r1, r2) are fixed. The spring member (13) is arranged in the circumferential gap (δ) of the fitting portion with 1).

According to the present invention, the torque fluctuations in the two planetary gear mechanisms adjacent to each other in the axial direction are absorbed by the elastic deformation of the spring member, so that the collision between the spline teeth of the ring gear and the spline teeth of the housing is prevented, and the collision between the two is prevented. The generation of rattling noise is prevented and the power transmission device is made quieter.

Further, in the power transmission device (100), it is desirable that a plurality of the spring members (13) are arranged at equal angle pitches in the circumferential direction.

By arranging the plurality of spring members at equal angles in the circumferential direction in this way, the torque fluctuations in each planetary gear mechanism can be effectively and evenly absorbed in the circumferential direction by the plurality of spring members.

Further, in the power transmission device (100), the spring member (13) is formed by bending a metal plate or bar in a dogleg shape, and both end portions in the longitudinal direction thereof are adjacent to each ring gear (r1). , R2), respectively, and it is preferable that the bent portion in the middle in the longitudinal direction is arranged so as to abut on the housing (1).

In this case, the contact points (P) of the bent portion of the spring member (13) with the housing (1) are located at both ends of the spring member (13) in the longitudinal direction. It is desirable that the moments (M1, M2) in opposite directions centering on the contact point (P) due to the forces acting from (F1, F2) are arranged at a balanced position.

According to the above configuration, the moments due to the forces acting from the ring gears of the two planetary gear mechanisms are balanced and cancel each other at both ends in the longitudinal direction of the spring member, so that the spline teeth of the ring gears come into contact with the spline teeth of the housing. However, it is possible to prevent abnormal noise such as rattling noise.

According to the present invention, in the planetary gear mechanism of the power transmission device, it is possible to obtain an effect that it is possible to prevent the generation of abnormal noise such as rattling noise due to torque fluctuation.

It is a vertical cross-sectional view which shows typically the basic structure of the power transmission device which concerns on this invention. It is a speed diagram of the planetary gear mechanism of the power transmission device which concerns on this invention. It is a half-cut sectional view of the planetary gear mechanism part of the power transmission device which concerns on this invention. FIG. 3 is a cross-sectional view taken along the line AA of FIG. It is an enlarged cross-sectional view of part B of FIG. FIG. 5 is a cross-sectional view taken along the line CC of FIG. It is a perspective view of a spring member.

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

FIG. 1 is a vertical sectional view schematically showing a basic configuration of a power transmission device according to the present invention, FIG. 2 is a speed diagram of a planetary gear mechanism of the power transmission device, and the power transmission device 100 shown in FIG. 1 is a speed diagram. It is mounted on an electric vehicle (EV vehicle) (not shown) and has the following configuration.

That is, the power transmission device 100 shown in FIG. 1 includes an electric motor M as a drive source, a multi-stage speed reducer T, a differential mechanism (differential mechanism) D, and the like in the housing 1. More specifically, the inside of the housing 1 is divided into a motor chamber SM and a gear chamber SG by a partition wall 1A, an electric motor M as a drive source is housed in the motor chamber SM, and a multi-stage deceleration is performed in the gear chamber SG. The machine T and the differential mechanism D are housed. The electric motor M also functions as a generator during regeneration, and a battery is electrically connected to the electric motor M via an inverter (not shown), and the electric power supplied from the battery is connected to the electric motor M. The electric motor M is driven to rotate.

A rotatable hollow input shaft (motor shaft) 2 rotationally driven by the electric motor M is inserted in the center of the electric motor M, and both ends of the input shaft 2 in the axial direction are bearings (balls). It is rotatably supported by the housing 1 by a bearing) 3. An axial end portion (left end portion in FIG. 1) of the input shaft 2 penetrates the partition wall 1A of the housing 1 and faces the gear chamber SG.

The multi-stage speed reducer T housed in the gear chamber SG includes a first planetary gear mechanism PG1 and a second planetary gear mechanism PG2 arranged side by side adjacent to the axial direction of the input shaft 2 (left-right direction in FIG. 1). There is. Here, the first planetary gear mechanism PG1 includes a small-diameter sun gear s1 formed on the outer periphery of one end in the axial direction (left end in FIG. 1) extending to the gear chamber SG of the input shaft 2, and the inside of the housing 1. A large-diameter ring gear r1 fixed to the circumference and a plurality of pinion gears (planetary gears) p1 that revolve around the sun gear s1 while engaging with the sun gear s1 and the ring gear r1 and revolving around the sun gear s1. , The carrier c1 that supports these pinion gears p1 so as to be rotatable (rotating) is provided.

Further, the second planetary gear mechanism PG2 includes a small diameter sun gear s2 formed on the carrier c1 of the first planetary gear mechanism PG1, a large diameter ring gear r2 fixed to the inner circumference of the housing 1, a sun gear s2 and a ring gear r2. A plurality of pinion gears (planetary gears) p2 that revolve around the sun gear s2 while meshing with each other (only two are shown in FIG. 1) and a carrier c2 that supports these pinion gears p2 so that they can rotate (rotate). I have.

A case (diff case) 4 of the differential mechanism D is attached to the carrier c2 of the second planetary gear mechanism PG2. Since the configuration of the differential mechanism D is known, the description thereof will be omitted, but from this differential mechanism D, the left and right output shafts (axles) 5L and 5R are on the same axis in the vehicle width direction (FIG. 1). It extends along the left-right direction), and wheels (driving wheels) (not shown) are attached to the outer ends of the axles 5L and 5R, respectively. Here, the case (diff case) 4 of the differential mechanism D is rotatably supported by the housing 1 by the bearing (ball bearing) 6.

By the way, one output shaft (axle) 5R (on the right side of FIG. 1) penetrates the hollow portion of the carrier c2 of the second planetary gear mechanism PG2 and the hollow input shaft (motor shaft) 2 to the outside of the housing 1. The output shaft (axle) 5R and the input shaft (motor shaft) 2 are rotatably arranged along the same axis along the vehicle width direction (left-right direction in FIG. 1). An axial end portion (right end portion in FIG. 1) of the output shaft (axle) 5R is rotatably supported by the housing 1 by a bearing 7.

Thus, in the power transmission device 100 configured as described above, when the electric motor M is started and the input shaft (motor shaft) 2 is rotationally driven at a predetermined speed, the rotation of the input shaft 2 is rotated. It is decelerated by two stages by the first planetary gear mechanism PG1 and the second planetary gear mechanism PG2 and transmitted to the left and right output shafts (axles) 5L and 5R, respectively.

That is, as shown in FIG. 2, in the first planetary gear mechanism PG1, when the sun gear s1 formed on the input shaft (motor shaft) 2 is rotationally driven together with the input shaft 2 at a speed V1, the sun gear s1 rotates while rotating. The carrier c1 that supports the pinion gear p1 that revolves around the pinion gear p1 rotates at a speed (revolution speed of the pinion gear p1) V2 (<V1). As a result, the rotation of the input shaft (motor shaft) 2 is decelerated from the speed V1 to the speed V2 (<V1) by the first planetary gear mechanism PG1.

Then, in the second planetary gear mechanism PG2, as shown in FIG. 2, the sun gear s2 formed on the carrier c1 of the first planetary gear mechanism PG1 rotates at the same speed V2 as the carrier c1 and rotates while rotating on the sun gear s2. The carrier c2 that supports the pinion gear p2 that revolves around it rotates at a speed (revolution speed of the pinion gear p2) V3 (<V2).

As a result of the above, the rotation of the input shaft (motor shaft) 2 is decelerated by the first planetary gear mechanism PG1 and the second planetary gear mechanism PG2 in two steps from the speed V1 to the speed V3 (<V2 <V1). Then, the case (diff case) 4 of the differential mechanism D rotates at a speed V3 together with the carrier c2 of the second planet gear mechanism PG2, and this rotation is distributed by the differential mechanism D to the left and right output shafts (axles) 5L and 5R. And the left and right output shafts (axles) 5L and 5R are rotationally driven, respectively. As a result, the left and right wheels (driving wheels) attached to the outer ends of the left and right output shafts (axles) 5L and 5R are rotationally driven, so that the electric vehicle (EV vehicle) is predetermined. Drive at speed.

Next, the details of the configuration of the multi-stage speed reducer T will be described below with reference to FIGS. 3 to 6.

FIG. 3 is a half-cut sectional view of a planetary gear mechanism portion of the power transmission device according to the present invention, FIG. 4 is a sectional view taken along line AA of FIG. 3, FIG. 5 is an enlarged sectional view of portion B of FIG. 4, and FIG. 6 is FIG. CC line sectional view, FIG. 7 is a perspective view of a spring member.

As shown in FIG. 3, in the first planetary gear mechanism PG1, a plurality of pinion gears p1 (only one is shown in FIG. 3) are bearings (only one is shown in FIG. 3) with respect to the horizontal first pinion shaft 8 attached to the carrier c1. Needle bearings) 9 support each of them so that they can rotate (rotate).

Further, in the second planetary gear mechanism PG2, a plurality of pinion gears p2 (only one is shown in FIG. 3) are provided by bearings (needle bearings) 11 with respect to the horizontal second pinion shaft 10 attached to the carrier c2. Each is supported so that it can rotate (rotate). The carrier c2 of the second planetary gear mechanism PG2 is rotatably supported by the housing 1 by a bearing (ball bearing) 12.

By the way, as shown in FIG. 3, the ring gear r1 of the first planetary gear mechanism PG1 and the ring gear r2 of the second planetary gear mechanism PG2 are arranged side by side in the axial direction with a bearing (ball bearing) 12 sandwiched between them. The outer peripheral portions of these ring gears r1 and r2 are fixed to the inner peripheral portion of the housing 1 by spline fitting. Here, the details of the spline fitting portion of the housing 1 of the ring gear r1 of the first planetary gear mechanism PG1 are shown in FIG. 4. As shown in the figure, in this spline fitting portion, on the inner circumference of the housing 1. The plurality of spline teeth 1a formed and the plurality of spline teeth r1a formed on the outer periphery of the ring gear r1 are in mesh with each other. A plurality of circumferential gaps δ are formed between the spline teeth 1a of the housing 1 and the spline teeth r1a of the ring gear r1.

Further, as shown in FIG. 3, also in the spline fitting portion of the ring gear r2 of the second planetary gear mechanism PG2 to the housing 1, a plurality of spline teeth 1a formed on the inner circumference of the housing 1 and the outer periphery of the ring gear r2 Although the plurality of formed spline teeth r2a are in mesh with each other, a plurality of radial gaps δ are also formed between the two spline teeth 1a and r2a.

Thus, in the present embodiment, some of the plurality of circumferential gaps δ formed between the spline teeth 1a of the housing 1 and the spline teeth r1a and r2a of the ring gears r1 and r2 (in the present embodiment). In the four forms, as shown in FIGS. 3 to 6, spring members 13 that bend in a dogleg shape (or U shape or V shape, the same applies hereinafter) form both ring gears r1 and r2. They are arranged so as to straddle each other in the axial direction (see FIGS. 3 and 6). Here, as shown in FIG. 7, the spring member 13 is formed by bending a metal plate material such as spring steel into a dogleg shape, and in the present embodiment, the four spring members 13 are arranged in the circumferential direction. They are arranged at an equal angle pitch (90 ° pitch). The number of spring members 13 to be arranged is arbitrary. For example, when there are two spring members 13, the pitch is 180 ° in the circumferential direction, and when there are three, the pitch is 120 ° in the circumferential direction. In the case of one, the spring members are arranged at a pitch of 60 ° in the circumferential direction, and when the number of the spring members 13 is n, the arrangement angle in the circumferential direction is 360 ° / n. Further, the spring member 13 may be formed by bending a metal rod member (round rod or square rod) into a dogleg shape.

By the way, as shown in FIG. 6, each spring member 13 is in contact with two ring gears r1 and r2 adjacent to each other in the longitudinal direction at both ends in the longitudinal direction, and the bent portion in the middle in the longitudinal direction is in contact with the housing 1. Have been placed. Here, the contact point P of the bent portion of each spring member 13 with respect to the housing 1 is centered on the contact point P due to the forces F1 and F2 acting on both ends of the spring member 13 in the longitudinal direction from the ring gears r1 and r2. The moments M1 and M2 in opposite directions are arranged at a balanced position.

More specifically, the ring gears r1 and r2 receive torques T1 and T2 from a plurality of pinion gears p1 and p2, and the pinion gears p1 and p2 have the same speed V2 and V3 as the carriers c1 and c2 supporting them (FIG. 2). Revolve around the sun gears s1 and s2 (see speed diagram). Here, as is clear from FIG. 2, the revolution speed of the pinion gear p1 (rotational speed of the carrier c1) V2 is larger than the revolution speed of the pinion gear p2 (rotational speed of the carrier c3) V3 (V2> V3). The torque T1 received by the ring gear r1 from the pinion gear p1 is smaller than the torque T2 received by the ring gear r2 from the pinion gear p2 (T1 <T2).

Here, assuming that the radius of the meshing point of each ring gear r1 and r2 is r, the forces F1 and F2 acting on the spring member 13 from each ring gear r1 and r2 are expressed by the following equations, respectively.

F1 = T1 / r ... (1)
F2 = T2 / r ... (2)
As described above, since T1 <T2, the following magnitude relations are established for F1 and F2 from the above equations (1) and (2).

F1 <F2 ... (3)
Here, as shown in FIG. 6, assuming that the distances of the contact points P1 and P2 of the spring member 13 to the ring gears r1 and r2 from the contact points P to the housing 1 are L1 and L2, respectively, the forces F1 and F2 are applied. The moments M1 and M2 in opposite directions with respect to the contact point P are expressed by the following equations, respectively.

M1 = F1 x L1 ... (4)
M2 = F2 x L2 ... (5)
In order for these moments to be balanced (M1 = M2), the following relationship must be established.

F1 x L1 = F2 x L2 ... (6)
Therefore, the following relationship is established for the distances L1 and L2 from the bending points (contact points P to the housing 1) of both ends of the spring member 13 in the longitudinal direction (contact points P1 and P2 to the ring gears r1 and r2). ..

L1 / L2 = F2 / F1 ... (7)
Here, since F1 <F2 from the equation (3), the following magnitude relationship is established between L1 and L2.

L1> L2 ... (8)
In the above, in the present embodiment, there is a circumferential gap (specifically, a circumferential gap) between the first planetary gear mechanism PG1 and the second planetary gear mechanism PG2 ring rear r1 and r2 housings 1 adjacent to each other in the axial direction. , Circumferential gap between the spline teeth r1a and r2a of the ring gears r1 and r2 and the spline teeth 1a of the housing 1) Therefore, the torque fluctuations in the first planetary gear mechanism PG1 and the second planetary gear mechanism PG2 are absorbed by the elastic deformation of the spring member 13. Therefore, the collision between the spline teeth r1a and r2a of the ring gears r1 and r2 and the spline teeth 1a of the housing 1 is prevented, the generation of rattling noise due to the collision between the two is prevented, and the power transmission device 100 is made quieter. It is planned.

Further, in the present embodiment, since the plurality of spring members 13 are arranged at equal angles in the circumferential direction, the torque fluctuations in the planetary gear mechanisms PG1 and PG2 are effectively and evenly absorbed in the circumferential direction by the plurality of spring members 13. can do.

Further, in the present embodiment, the contact points P of the bent portions of the spring member 13 with respect to the housing 1 are the moments M1 due to the forces F1 and F2 acting on both ends of the spring member 13 in the longitudinal direction from the ring gears r1 and r2. , M2 are arranged at balanced positions, so that the spline teeth r1a and r2a of the ring gears r1 and r2 do not come into contact with the spline teeth 1a of the housing 1, and abnormal noise such as rattling noise can be prevented.

Although the embodiment in which the present invention is applied to a power transmission device mounted on an electric vehicle (EV vehicle) has been described above, the present invention describes a vehicle having only an engine as a drive source and an engine and an electric motor as a drive source. It can also be applied to a power transmission device mounted on a hybrid vehicle (HEV vehicle) in which the above is used in combination, or a power transmission device provided in an arbitrary device in which a plurality of planetary gear mechanisms other than the vehicle are arranged side by side in the axial direction. Is.

In addition, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of claims and the technical ideas described in the specification and drawings.

1 Housing 13 Spring member 100 Power transmission device F1, F2 Force acting on the spring member from the ring gear M1, M2 Moment acting on the spring member P Contact point of the spring member with the housing P1, P2 Contact point of the spring member with the ring gear PG1 1st planetary gear mechanism PG2 2nd planetary gear mechanism c1, c2 carrier p1, p2 pinion gear r1, r2 ring gear s1, s2 sun gear δ circumferential gap

Claims (5)

A power transmission device in which a plurality of planetary gear mechanisms arranged coaxially are housed in a housing, and each ring gear of the two planetary gear mechanisms adjacent in the axial direction is fixed to the housing.
A power transmission device characterized in that a bending spring member is arranged in a circumferential gap between each ring gear of the two planetary gear mechanisms adjacent in the axial direction and the housing so as to straddle both ring gears in the axial direction. .. Each ring gear of the two planetary gear mechanisms is fixed to the housing by spline fitting, and the spring member is arranged in a circumferential gap between the ring gear and the fitting portion of the housing. Item 1. The power transmission device according to item 1. The power transmission device according to claim 1 or 2, wherein a plurality of the spring members are arranged at equal angles in the circumferential direction. The spring member is formed by bending a metal plate or bar in a dogleg shape, both ends of the spring member abut on adjacent ring gears, and the bent portion in the middle of the longitudinal direction hits the housing. The power transmission device according to any one of claims 1 to 3, wherein the power transmission device is arranged so as to be in contact with each other. The contact points of the bent portion of the spring member with the housing are arranged at positions where moments in opposite directions centering on the contact points due to the forces acting from the ring gears are balanced at both ends of the spring member in the longitudinal direction. The power transmission device according to claim 4, wherein the power transmission device is provided.

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