JP2019089367A - Power transmission device - Google Patents

Abstract

To prevent a noise from occurring due to the membrane vibration of a case.SOLUTION: A power transmission device includes: a power division mechanism dividing power output from an engine into a motor 2 side and a driven wheel side; a case 7 accommodating a motor 2 disposed on an engine side nearer than the power division mechanism; and a bearing 6 disposed on an end 21c of a rotor shaft 21a on the engine side. The power transmission device, in which the rotor shaft 21a has a flange part 21d extending outward in a radial direction toward a rotor core 21b, includes a damper mechanism 8 disposed in a manner of being sandwiched axially between the flange part 21d and an inner race 61 of the bearing 6. The damper mechanism 8 absorbs an axial load when the rotor shaft 21a is displaced axially so as to approach the inner race 61.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power transmission device.

  Patent Document 1 discloses a power transmission device provided with a power split mechanism capable of splitting power output from an engine into an electric motor side and a drive wheel side.

JP, 2008-113540, A

  In the configuration described in Patent Document 1, when the power (engine torque) output from the engine is transmitted to the motor side, the engine torque is transmitted to the rotor shaft of the motor via the meshing portion between the pinion gear and the sun gear of the power split mechanism. Be done. However, since the sun gear is formed by a helical gear, the rotational fluctuation (torque fluctuation) of the engine is transmitted to the rotor shaft to cause axial vibration in the rotor shaft. When this axial vibration is transmitted from the rotor shaft to the case via the bearing, the case vibrates in a film. Therefore, abnormal noise may occur due to membrane vibration of the case.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a power transmission device capable of suppressing the generation of abnormal noise due to film vibration of a case.

  According to the present invention, a power split mechanism that splits the power output from the engine into the motor side and the drive wheel side, a case that houses the motor disposed closer to the engine side than the power split mechanism, and the rotor shaft of the motor A power transmission device including a bearing disposed at an end portion on an engine side and rotatably supporting a rotor shaft with respect to a case, the rotor shaft having a flange portion radially outwardly extending toward the rotor core; And an inner ring of the bearing, the damper being disposed between the inner ring and the inner ring of the bearing to absorb an axial load when the rotor shaft is axially displaced so as to approach the inner ring.

  In the present invention, a damper that absorbs an axial load is disposed between the flange portion of the rotor shaft and the inner ring of the bearing. When the power output from the engine is transmitted to the rotor shaft via the power split mechanism, the axial load can be absorbed by the damper even if the rotor shaft vibrates in the axial direction due to the rotational fluctuation of the engine. As a result, it is possible to reduce axial vibration that is input from the rotor shaft to the case via the bearing, so it is possible to suppress the generation of abnormal noise due to film vibration of the case.

FIG. 1 is a skeleton diagram schematically showing an example of a vehicle equipped with the power transmission device of the embodiment. FIG. 2 is a cross-sectional view for explaining the support structure of the rotor shaft. FIG. 3 is a cross-sectional view for explaining the damper mechanism.

  The power transmission device according to an embodiment of the present invention will be specifically described below with reference to the drawings.

  FIG. 1 is a skeleton diagram schematically showing an example of a vehicle Ve equipped with the power transmission device 10 of the embodiment. Vehicle Ve on which power transmission device 10 is mounted is a hybrid vehicle in which engine (ENG) 1 and motor generator (MG) 2 function as a power source. The motor generator 2 has a motor function of supplying power and outputting power, and a power generation function of being forcibly rotated by a mechanical external force to generate electric power, and is constituted by, for example, a synchronous motor of permanent magnet type, etc. Ru. As shown in FIG. 1, the motor generator 2 includes a rotor 21 and a stator 22. The rotor 21 is configured such that the rotor shaft 21a and the rotor core 21b rotate integrally. In the following description, the motor generator is simply referred to as a motor.

  The power transmission device 10 includes a power split mechanism 3 in the power transmission path from the engine 1 to the drive wheels (not shown), and the power (engine torque) output from the engine 1 is transmitted to the motor 2 side and the drive wheel side. It is configured to be divisible. The motor 2 is made to function as a generator by the power divided to the motor 2 side.

  The power split mechanism 3 is configured by a single pinion type planetary gear mechanism, and is connected to the engine 1 via an input shaft 4. As shown in FIG. 1, the power split mechanism 3 is capable of rotating and revolving the sun gear 3S, the ring gear 3R concentrically arranged with respect to the sun gear 3S, and the pinion gear meshing with the sun gear 3S and the ring gear 3R. And the carrier 3C held by the The motor 2 is connected to the sun gear 3S. The engine 1 is connected to the carrier 3C. Connected to the ring gear 3R is an output gear 5 for outputting power from the power split mechanism 3 toward the drive wheels. For example, the ring gear 3R and the output gear 5 are integrally formed.

  The input shaft 4 is a rotating shaft disposed on the same axis as the crankshaft of the engine 1 and is connected to rotate integrally with the crankshaft. For example, the crankshaft is connected to the input shaft 4 via a flywheel or a damper 11 (shown in FIG. 2). When the engine 1 is driven, the engine torque is input from the crankshaft to the damper 11 via the flywheel and transmitted from the damper 11 to the power split mechanism 3 via the input shaft 4.

  The motor 2 and the power split mechanism 3 are disposed on the outer peripheral side of the input shaft 4. That is, the rotor shaft 21a and the sun gear 3S rotate around the rotation center axis of the input shaft 4 as a rotation center. Specifically, the sun gear 3S has a hollow sun gear shaft. The rotor shaft 21a is a hollow shaft. The inner peripheral portion of the sun gear shaft and the outer peripheral portion of the rotor shaft 21a are spline-fitted. The input shaft 4 is disposed so as to penetrate the inside of the rotor shaft 21a and the inside of the sun gear 3S (sun gear shaft). The rotor shaft 21a is mounted to the case 7 (shown in FIG. 2) by a bearing (not shown) provided at the end on the sun gear 3S side and a bearing 6 provided at the end on the engine 1 side. It is rotatably supported.

  FIG. 2 is a cross-sectional view for explaining the support structure of the rotor shaft 21a. The rotor shaft 21a is supported by the case 7 via a bearing 6 provided at an end 21c on the engine 1 side. The bearing 6 is a rolling bearing having an inner ring 61 attached to the rotor shaft 21 a and an outer ring 62 attached to the case 7. The front side (Fr) shown in FIG. 2 represents the engine 1 side and the rear side (Rr) represents the opposite side to the engine 1 on one side and the other side in the axial direction.

  The case 7 accommodates the motor 2 therein, and includes a front cover 71 disposed on the front side with respect to the motor 2 and constituting a case wall. In addition to the motor 2, the power split mechanism 3 is also housed inside the case 7. On the other hand, the damper 11 is disposed outside the case 7 (the engine 1 side of the front cover 71). The damper 11 is a torsional damper provided on the input shaft 4, and a torsion spring disposed between an input element integrally rotating with the flywheel and an output element integrally rotating with the input shaft 4 is directed in the rotational direction. By expanding and contracting, torque fluctuations can be absorbed.

  The front cover 71 is provided with a fixing portion 71 a to which the bearing 6 is attached. The fixing portion 71a has a cylindrical structure in which a portion of the front cover 71 protrudes toward the rear in the axial direction and is disposed radially inward of the rotor core 21b. The outer peripheral portion of the outer ring 62 is fitted to the inner peripheral portion of the fixed portion 71a. The arrangement of the bearings 6 is on the inner side in the radial direction of the rotor core 21b.

  Further, the rotor shaft 21a is provided with a flange portion 21d which is expanded radially outward toward the rotor core 21b side. The end portion 21c extends to the front side in the axial direction more than the flange portion 21d. Furthermore, an axial displacement absorbing damper (hereinafter referred to as "damper mechanism") 8 is disposed between the flange portion 21d and the inner ring 61 in the axial direction, which absorbs an axial load when the rotor shaft 21a is displaced in the axial direction. It is done. The damper mechanism 8 has a damper function to absorb axial vibration generated in the rotor shaft 21a. An example of a specific structure of the damper mechanism 8 is shown in FIG.

  FIG. 3 is a cross-sectional view for explaining an example of the damper mechanism 8. The damper mechanism 8 includes a damper inner guide 8a, a spring 8b, a stroke stopper 8c, a damper outer guide 8d, and a stroke stopper 8e. Further, a damper guide 21 e is provided on the radially outer side of the damper mechanism 8 such that a wall surface (holding surface) for holding the damper mechanism 8 is directed radially inward. The damper guide 21e protrudes from the flange portion 21d of the rotor shaft 21a in the axial direction to the front side. Even when the rotor shaft 21a rotates at high speed, the damper guide 21e can prevent the damper mechanism 8 from being shaken by centrifugal force.

  The damper inner guide 8a is a holding member in contact with the outer peripheral surface of the rotor shaft 21a and the front side surface of the flange portion 21d. The spring 8 b is an elastic member that is axially contracted when the rotor shaft 21 a is axially displaced so as to approach the inner ring 61, and absorbs an axial load. The damper outer guide 8d is a holding member in contact with the rear side surface of the inner ring 61 and the inner peripheral surface of the damper guide 21e. Both axial ends of the spring 8b are sandwiched by the damper inner guide 8a and the damper outer guide 8d. For example, when the spring 8b expands and contracts in the axial direction, the outer peripheral surface of the damper outer guide 8d slides on the inner peripheral surface (holding surface) of the damper guide 21e in the axial direction.

  The stroke stoppers 8c and 8e are portions for restricting the movement of the rotor shaft 21a to the front side in the axial direction, and when the rotor shaft 21a is displaced in the axial direction, the front end portion of the damper guide 21e is a bearing 6 It is a stopper member for preventing contact. As shown in FIG. 3, the stroke stopper 8c is a stopper on the side of the flange portion 21d, and is in contact with the side surface on the front side of the damper inner guide 8a. The stroke stopper 8e is a stopper on the inner ring 61 side (the bearing 6 side), and is in contact with the rear side surface of the damper outer guide 8d. When the rear side stroke stopper 8c abuts on the front side stroke stopper 8e, the further movement of the rotor shaft 21a to the front side in the axial direction (the spring 8b is further contracted in the axial direction) is restricted. As shown in FIG. 3, a stopper clearance CL, which is a gap in the axial direction, is provided between the stroke stopper 8c and the stroke stopper 8e. The stopper clearance CL is a stroke amount of the rotor shaft 21a, that is, an axial distance which allows the spring 8b to be maximally contracted. For example, the axial distance (gap) between the front end of the damper guide 21e and the bearing 6 is set to be equal to or less than the stopper clearance CL. Thereby, the damper guide 21 e is prevented from coming into contact with the bearing 6. Further, the wall surface height (the position in the radial direction of the holding surface) of the damper guide 21 e is set to the height (the position in the radial direction) between the inner ring 61 and the outer ring 62 of the bearing 6.

  Furthermore, regarding the mounting structure of the bearing 6, the inner ring 61 is loosely fitted (non-press-fit) to the outer peripheral portion of the rotor shaft 21a, and the outer ring 62 is tightly fitted (press-fit) to the fixed portion 71a of the case 7. There is. Since the outer ring 62 is tightly fitted to the case 7, the axial displacement of the rotor shaft 21 a can not be absorbed by the fitting portion between the outer ring 62 and the case 7. On the other hand, since the inner ring 61 is loosely fitted to the rotor shaft 21a and the inner ring 61 and the rotor shaft 21a can be relatively displaced in the axial direction, the axial displacement of the rotor shaft 21a on the inner ring 61 side Need to absorb. Therefore, the damper mechanism 8 is disposed between the inner ring 61 and the flange portion 21d. The axial vibration (axial load) is absorbed by the damper mechanism 8 to suppress the axial vibration from being input from the rotor shaft 21a to the front cover 71 (case 7).

  For example, the state shown in FIG. 3 is a steady state in which the damper mechanism 8 does not absorb the axial load, and the stopper clearance CL is present. When the rotor shaft 21a is displaced so as to approach the front side, ie, the inner ring 61 in the axial direction, the damper mechanism 8 absorbs an axial load. Then, when the rotor shaft 21a is displaced to the front side in the axial direction, the spring 8b is contracted in the axial direction, the stroke stopper 8c is stroked so as to approach the stroke stopper 8e, and the stroke stoppers 8c and 8e contact with each other. In the state where the stroke stoppers 8 c and 8 e are in contact with each other, the stopper clearance CL disappears, and the damper guide 21 e remains at the axial position away from the bearing 6. Furthermore, since the spring 8b pushes the damper inner guide 8a to the rear in the axial direction and pushes the damper outer guide 8d to the front in the axial direction, a load that acts on the rear in the axial direction so that the stroke stopper 8c separates from the stroke stopper 8e. Is applied to the rotor shaft 21a. Thus, the rotor shaft 21 a can be moved to the rear side in the axial direction by the damper mechanism 8.

  As described above, by disposing the damper mechanism 8 between the flange portion 21 d of the rotor shaft 21 a and the inner ring 61 of the bearing 6, the damper mechanism 8 exerts an axial load when the rotor shaft 21 a vibrates in the axial direction. It can be absorbed. Thereby, even when the rotor shaft 21a vibrates in the axial direction due to the rotational fluctuation (torque fluctuation) of the engine 1, transmission of the vibration in the axial direction to the case 7 via the bearing 6 can be suppressed. As a result, the film vibration of the case 7 (front cover 71) can be suppressed, and the generation of abnormal noise due to the film vibration can be suppressed. Furthermore, by providing the stroke stoppers 8c and 8e, even if the damper mechanism 8 is deformed so as to be compressed in the axial direction, the damper guide 21e can be prevented from contacting the bearing 6.

  There is an operating range where the vibration reduction effect by the damper mechanism 8 is increased according to the driving state of the engine 1. When the engine 1 is in idle operation, that is, in the low rotation speed region where the engine rotation speed is the idle rotation speed, the frequency region is close to the natural frequency of the front cover 71 (case 7). As the axial vibration of the rotor shaft 21a in this region is absorbed by the damper mechanism 8, the effect of reducing the film vibration of the front cover 71 is enhanced, and the generation of noise can be effectively suppressed. Become.

  In addition, this invention is not limited to embodiment mentioned above, It can change suitably in the range which does not deviate from the objective of this invention. For example, power transmission device 10 may be mounted on a two-motor hybrid vehicle equipped with a second motor generator (MG2) in addition to motor 2 described above. In this case, the above-described motor 2 is the first motor generator (MG1), and the power transmission device 10 includes the second planetary gear mechanism functioning as a transmission unit in addition to the power split mechanism 3. The transmission unit includes a sun gear connected to the second motor generator, a carrier as a fixed element fixed to the case, and a ring gear as an output element integrally rotating with the ring gear 3R of the power split mechanism 3. The second motor generator and the transmission unit are disposed coaxially with the crankshaft of the engine 1. In the axial arrangement, the motor 2, the power split mechanism 3, the transmission unit, and the second motor generator are arranged in this order from the engine 1 side. The power transmission device 10 is also housed inside the case 7.

1 Engine 2 Motor 3 Power Splitting Mechanism 4 Input Shaft 5 Output Gear 6 Bearing 7 Case 8 Damper Mechanism (Axial Displacement Absorber Damper)
8a Damper inner guide 8b Spring 8c Stroke stopper 8d Damper outer guide 8e Stroke stopper 10 Power transmission device 21 Rotor 21a Rotor shaft 21b Rotor core 21c End 21d Flange 21e Damper guide 22 Stator 61 Inner ring 62 Outer ring 71 Front cover 71a Fixing portion CL stopper clearance

Claims (1)

A power split mechanism that splits the power output from the engine into the motor side and the drive wheel side;
A case that accommodates the motor disposed closer to the engine than the power split mechanism;
A bearing disposed at an end portion of the rotor shaft of the motor on the engine side and rotatably supporting the rotor shaft with respect to the case;
Equipped with
In the power transmission apparatus, in the power transmission device, the rotor shaft may have a flange portion radially outwardly extending toward the rotor core.
A damper is disposed axially interposed between the flange portion and the inner ring of the bearing, and which absorbs an axial load when the rotor shaft is axially displaced so as to approach the inner ring. Power transmission device.

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