JP2019190521A - Torque converter for electrically-driven vehicle - Google Patents

Abstract

To provide a torque converter for an electrically-driven vehicle capable of reducing power loss caused by a sliding of an electrically-driven vehicle at the time of its starting and securing a requisite driving power at the time of high load.SOLUTION: In a torque converter 1 for an electrically-driven vehicle constituted such that a pump impeller 2 connected to an input shaft 32 and a turbine runner 3 connected to an output shaft 33 are oppositely arranged, a stator 4 is arranged among these pump impeller 2 and the turbine runner 3 and a lock-up clutch 9 directly connecting the input shaft 32 and the output shaft 33 under a predetermined condition by being turned ON/OFF by hydraulic fluid pressure and a damper mechanism 8 arranged between the turbine runner 3 and the output shaft 33 are provided, there are provided a spring (a pressure applying mechanism) 27 for turning ON the lock-up clutch 9 at a low torque state where an electric vehicle starts to move, and a releasing mechanism for turning OFF the lock-up clutch 9 kept in ON state in response to a transmittance torque.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electric vehicle torque converter provided in an electric drive unit mounted on an electric vehicle (EV vehicle).

  In recent years, for the purpose of a low-carbon society, hybrid vehicles (HEV vehicles) (for example, see Patent Document 1) and electric vehicles (EV vehicles) based on exhaust gas regulations have been widely used. There is still a great need for a large driving force during towing.

  However, in order to realize a high driving force only with the electric motor, it is necessary to increase the torque of the electric motor, and there is a problem that an increase in the size and weight of the electric motor cannot be avoided.

  As means for solving the above problems, proposals have been made to provide a plurality of electric motors or to add a transmission or a torque converter. However, by providing a plurality of electric motors, a higher driving force can be realized, but the cost increases. There is a problem that you cannot escape. In addition, by adding a transmission, a high driving force can be secured with a small motor, but a problem of an increase in cost occurs.

  If a torque converter is added, a necessary driving force can be secured while suppressing an increase in cost. The torque converter provided in the electric vehicle is arranged such that a pump impeller connected to the output shaft of the electric motor and a turbine runner connected to the input shaft of the reduction gear are opposed to each other, and between the pump impeller and the turbine runner. And a lockup clutch that directly connects the output shaft and the input shaft under a predetermined condition by being turned on and off by operating hydraulic pressure, and filled with oil that is a torque transmission medium. Has been.

JP 2017-019394 A

  However, in a general torque converter, if the lockup clutch is not ON (connected) when the electric vehicle starts, a power loss due to slip occurs. Here, the characteristics of the conventional torque converter provided in the electric vehicle are shown in FIG. 9. In the conventional torque converter, the motor rotation speed (pump impeller rotation speed) and the turbine rotation speed (turbine runner rotation speed) are between. While there is a difference, the lock-up clutch is turned off (indicated as “LC OFF” in FIG. 9), and the turbine torque (torque transmitted to the turbine runner) by torque amplification is greater than the motor torque (motor output torque). Also try to get bigger. In this case, power loss due to slippage between the motor rotation speed and the turbine rotation speed inevitably occurs.

  By the way, in an electric vehicle, since the torque fluctuation of the electric motor which is a drive source is small, a smooth start is possible. Therefore, at the time of start, the lockup clutch is turned on (connected) to reduce power loss due to slipping. desirable.

  However, as shown in FIG. 9, when the vehicle is started, the lockup clutch cannot be turned on because the hydraulic pressure for turning on the lockup clutch (lockup ON hydraulic pressure) is 0 or very low. In order to turn on the lock-up clutch at the time of starting, an expensive device such as an electric oil pump (EOP) is required, and an increase in cost is inevitable.

  In the conventional torque converter, as shown in FIG. 9, the lock-up clutch is turned on (indicated as “LC ON” in FIG. 9) when the motor rotation speed and the turbine rotation speed are substantially equal, and the motor The input shaft and the output shaft to the speed reducer are directly connected to increase power transmission efficiency.

  However, there are cases where it is desired to use the torque amplification function of the torque converter to obtain the required driving force even when the lockup clutch is in the high load range. Can not respond to.

  The present invention has been made in view of the above problems, and an object of the present invention is to realize both reduction of power loss due to slippage at the start of an electric vehicle and securing of necessary driving force at high load. An object of the present invention is to provide a torque converter for an electric vehicle.

  In order to achieve the above object, the present invention is arranged between an electric motor (31) and a speed reducer (40) of an electric motor drive unit (30) mounted on an electric vehicle, and an input shaft of the electric motor (31) ( The pump impeller (2) connected to 32) and the turbine runner (3) connected to the output shaft (33) to the speed reducer (40) are arranged to face each other, and these pump impeller (2) and turbine A lockup clutch that disposes the stator (4) between the runner (3) and that is turned ON / OFF by operating hydraulic pressure to directly connect the input shaft (32) and the output shaft (33) under a predetermined condition. (9) and an electric vehicle configured by providing a damper mechanism (8) provided between the turbine runner (3) and the output shaft (33) and filling oil as a torque transmission medium therein. Torque for In the inverter (1), the pressurizing mechanism (27) for turning on the lock-up clutch (9) at low torque when the electric vehicle starts, and the lock-up clutch (9) in the ON state according to the transmission torque And a release mechanism for turning it off.

  According to the torque converter according to the present invention, the power loss caused by the slip at the time of starting can be kept low because the lockup clutch is turned on by the pressurizing mechanism at the time of low torque when the electric vehicle starts. In addition, a release mechanism that turns off the lock-up clutch in the ON state according to the transmission torque is provided, so if a large driving force is required in a high load range, the lock-up clutch is turned off by the release mechanism and the torque converter A large driving force can be obtained by amplifying the torque by the torque amplifying action. As a result, it is possible to realize both reduction of power loss due to slippage at the start of the electric vehicle and securing of necessary driving force at high load.

  In the present invention, the lock-up clutch (9) includes a piston (18) that slides by operating hydraulic pressure to turn the lock-up clutch (9) on and off, and the pressurizing mechanism (27) includes: It is good also as what is comprised by the spring which urges | biases the said piston (18) in the direction which the said lockup clutch (9) turns on.

  In the present invention, the damper mechanism (8) includes an output member (10) coupled to the output shaft (33), and an input that can rotate relative to the output member (10) within a predetermined angle range. A member (11, 12), and an elastic member (13) for power transmission that absorbs torque fluctuation by elastic deformation by the relative rotation of the input member (11, 12) and the output member (10). The release mechanism may include a cam mechanism that converts relative rotation of the input member (11, 12) and the output member (10) of the damper mechanism (8) into sliding of the piston (18). .

  In the present invention, the cam mechanism is a cam formed on a piston member (28) that engages with the input member (11), rotates integrally with the input member (11), and is movable in the axial direction. (28C) and the cam (10B) formed on the output member (10) may be engaged with each other.

  In the present invention, the release mechanism may turn off the lock-up clutch (9) in the ON state when it is necessary to amplify the transmission torque in a high load range.

  ADVANTAGE OF THE INVENTION According to this invention, coexistence with reduction of the power loss by the slip at the time of start of an electric vehicle and ensuring of the required driving force at the time of a heavy load is realizable.

It is a skeleton figure which shows the structure of the electric drive unit provided with the torque converter for electric vehicles concerning this invention. 1 is a half sectional view of a torque converter for an electric vehicle according to the present invention. It is a perspective view of an input member, an output member, and a piston member which constitute a damper mechanism of a torque converter for electric vehicles concerning the present invention. It is a perspective view of the piston member and output member principal part of the torque converter for electric vehicles concerning the present invention. FIG. 3 is an enlarged detail view of a part A in FIG. 2. (A)-(c) is the BB sectional drawing of FIG. 5 which shows the effect | action of a cancellation | release mechanism. It is a figure which shows the relationship between the relative angle of an input / output member and the input torque in the cancellation | release mechanism of the torque converter for electric vehicles concerning this invention. It is a characteristic view of the torque converter for electric vehicles concerning this invention. It is a characteristic view of the conventional torque converter for electric vehicles.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Configuration of electric drive unit]
First, the configuration of an electric drive unit including an electric vehicle torque converter (hereinafter simply referred to as “torque converter”) according to the present invention will be described with reference to FIG.

  FIG. 1 is a skeleton diagram showing the configuration of an electric drive unit. The illustrated electric motor drive unit 30 is mounted on an electric vehicle (EV vehicle) and includes an electric motor 31 as a drive source. Here, the electric motor 31 is constituted by a three-phase brushless motor in the present embodiment, and has a hollow rotor 31a rotatably accommodated in a housing (not shown), and a solid around the rotor 31a. A ring-shaped stator 31b is provided. Although not shown, a permanent magnet is built in the rotor 31a, and coils for three phases are wound around the stator 31b.

  A cylindrical input shaft 32 arranged along the vehicle width direction (left-right direction in FIG. 1) is inserted and fixed at the shaft center of the rotor 31a of the electric motor 31, and the input shaft 32 is attached to the present invention. The torque converter 1 is connected to the pump impeller 2. Here, although details of the configuration of the torque converter 1 according to the present invention will be described later, the torque converter 1 includes a turbine runner 3 disposed opposite to the pump impeller 2 and a damper attached to the turbine runner 3. A mechanism 8 and a lock-up clutch 9 are provided.

  From the center of the turbine runner 3 of the torque converter 1, an output shaft 33 passes through the shaft center of the input shaft 32 and extends horizontally along the vehicle width direction. A small-diameter gear 41 of the speed reducer 40 is fixed to the right end portion. The gear 41 meshes with a large-diameter gear 43 that is fixed to a counter shaft 42 that is arranged in parallel to the output shaft 33. A small-diameter gear 44 is fixed to the counter shaft 42, and the gear 44 meshes with a large-diameter ring gear 45 fixed to a differential device (differential device) 50. Here, the gear 41 and the gear 43 and the gear 44 and the ring gear 45 having different diameters that mesh with each other constitute a reduction gear train in the reduction gear 40.

  The differential device 50 bisects the torque input thereto and transmits it to the left and right axles 51, and left and right drive wheels 60 are attached to the ends of the left and right axles 51, respectively.

  In the electric motor drive unit 30 configured as described above, when the electric motor 31 as a drive source is started and the input shaft 32 rotates together with the rotor 31a of the electric motor 31, the rotation is transferred to the output shaft 33 via the torque converter 1. The output shaft 33 is rotated by being transmitted. Details of the torque converter 1 and the damper mechanism 8 and the lockup clutch 9 provided on the torque converter 1 will be described later.

  The rotation of the output shaft 33 is decelerated through the gears 41 and 43 constituting the reduction gear train and transmitted to the counter shaft 42. The rotation of the counter shaft 42 is coupled with the gear 44 constituting the reduction gear train. It is transmitted to the differential device 50 through the ring gear 45. In the differential device 50, the torque transmitted to the differential device 50 is divided into two and transmitted to the left and right axles 51. Therefore, the left and right drive wheels 60 attached to the left and right axles 51 are driven to rotate, and the electric vehicle travels. To do.

[Configuration of torque converter]
Next, the detail of the structure of the torque converter 1 concerning this invention is demonstrated below based on FIGS.

  2 is a half sectional view of a vehicle torque converter according to the present invention, FIG. 3 is a perspective view of an input member, an output member and a piston member of the damper mechanism, and FIG. 4 is a perspective view of a piston member and an output member main part of the damper mechanism. FIG. 5 is an enlarged detail view of part A of FIG. 2, FIGS. 6A to 6C are cross-sectional views taken along the line BB of FIG. 5, and the torque converter shown in FIG. Is transmitted to the output shaft through oil as a torque transmission medium, and has a smooth clutch function and a torque amplification function.

  A torque converter 1 shown in FIG. 2 includes a pump impeller 2 that is rotationally driven by an input shaft 32 shown in FIG. 1 and a turbine runner 3 that is disposed to face the pump impeller 2. A stator 4 is disposed between the turbine runner 3 and the turbine runner 3.

  The pump impeller 2 is configured by arranging a plurality of impeller blades 2a on the inner surface close to the outer periphery of a bowl-shaped pump shell 2A at an equiangular pitch in the circumferential direction. The pump shell 2A is also a bowl-shaped converter. It is bound to the cover 5. A sealed space S is formed by the pump shell 2A and the converter cover 5, and the sealed space S is filled with oil having a low viscosity as a torque transmission medium.

  Similarly to the pump impeller 2, the turbine runner 3 is configured by arranging a plurality of turbine blades 3a on the inner surface facing the pump impeller 2 near the outer peripheral portion of the bowl-shaped turbine shell 3A at an equiangular pitch in the circumferential direction. Yes. The stator 4 that is an impeller is disposed between the pump impeller 2 and the turbine runner 3, and a plurality of components for rectifying the oil flow and amplifying the torque are provided on the outer periphery of the stator 4. Stator blades 4a are arranged at an equiangular pitch in the circumferential direction. The stator 4 is provided with a one-way clutch 6, and the stator 4 can be stationary or idling by the action of the one-way clutch 6. Here, the pump impeller 2 and the stator 4 are supported by a bearing (thrust bearing) 7 interposed therebetween so as to be relatively rotatable.

  Incidentally, in the torque converter 1 according to the present embodiment, a damper mechanism 8 and a lockup clutch (LC) 9 are accommodated between the turbine runner 3 and the converter cover 5 in the sealed space S.

  The damper mechanism 8 is for absorbing torque fluctuations of the electric motor 31 shown in FIG. 1, and is a disc-shaped output member 10 bonded to the output shaft 33 shown in FIG. 1 by spline fitting, Between the output member 10 and both input members 11, 12, ring-shaped input members 11, 12 are arranged so as to be relatively rotatable on both sides of a flange portion 10 A extending radially outward from the outer periphery of the output member 10. 4 and includes four compression coil springs 13 (see FIG. 3). The damper mechanism 8 and the stator 4 are supported so as to be relatively rotatable by a bearing (thrust bearing) 14 interposed therebetween. Further, the four compression coil springs 13 are arranged at an equiangular pitch in the circumferential direction (see FIG. 3).

  Here, both the input members 11 and 12 are connected by a plurality (six) of connecting pins 15, and each connecting pin 15 has six long holes formed in the flange portion 10 </ b> A of the output member 10 in the circumferential direction. 10a (see FIG. 3). As shown in FIG. 3, the six long holes 10a are formed at an equal angular pitch (60 ° pitch) in the circumferential direction.

  Therefore, the input members 11 and 12 can rotate relative to the output member 10 in an angular range in which the connecting pins 15 can move in the circumferential direction in the long holes 10 a formed in the flange portion 10 </ b> A of the output member 10. is there. Similarly, the input members 11, 12 and the turbine runner 3 (turbine shell 3 </ b> A) are connected by a connecting pin 16, and the connecting pin 16 has a long hole 10 b formed in the flange portion 10 </ b> A of the output member 10. By penetrating, the input members 11 and 12 and the turbine runner 3 can rotate relative to the output member 10 within a predetermined angular range (an angular range in which the connecting pin 16 can move in the circumferential direction within the long hole 10b). As described later, the torque fluctuation of the electric motor 31 transmitted through the turbine runner 3 is caused by the four compression coil springs 13 accompanying the relative rotation between the input members 11 and 12 of the damper mechanism 8 and the output member 10. Absorbed by elastic deformation.

  The lock-up clutch (LC) 9 is provided on a ring plate-like piston 18 that is spline-fitted to the outer periphery of the hub 17 so as to be slidable in the axial direction (left-right direction in FIG. 2). The friction clutch 19 is used. Here, a retainer 20 is bound to the inner surface of the converter cover 5, and a retainer 21 is attached to the outer peripheral portions of both the input members 11 and 12 by pins 22. The friction clutch 19 has two friction plates 23 whose outer periphery engages with the inner periphery of the retainer 20 so as to be axially movable, and the inner periphery of the friction clutch 19 can move axially with the outer periphery of the retainer 21. Two disk plates 24 to be engaged are provided, and the friction plates 23 and the disk plates 24 are alternately arranged in the axial direction.

  As described above, each of the two friction plates 23 and the disk plates 24 arranged alternately in the axial direction is sandwiched between the stopper 25 fixed to the inner periphery of the retainer 20 and the outer peripheral portion of the piston 18. The disc spring 26 is biased toward the stopper 25 side.

  Here, a fastening chamber S1 and an open chamber S2 defined by the piston 18 are formed in the sealed space S. When hydraulic oil (pressure oil) is supplied from an oil pump (not shown) to the fastening chamber S1. The piston 18 that receives the pressure of the hydraulic oil moves to the right in FIG. 2 and presses the friction plate 23 and the disk plate 24 of the friction clutch 19 against the stopper 25, so that the friction plate 23 and the disk plate 24 are Power can be transmitted by the frictional resistance generated between the two in the engaged state, and the lockup clutch 9 is turned on (connected). In contrast, when hydraulic oil is supplied from an oil pump (not shown) to the open chamber S2, the piston 18 that receives the pressure of the hydraulic oil moves to the left in FIG. In order to release the engaged state between the disc plate 24 and the disc plate 24, the lock-up clutch 9 is turned off (disconnected).

  By the way, in the present embodiment, the lockup is performed at the time of low torque when the electric vehicle starts (when hydraulic oil having a pressure required to turn on the lockup clutch 9 cannot be supplied to the fastening chamber S1). A pressurizing mechanism for turning on the clutch 9 is provided, and this pressurizing mechanism is configured by a spring (coil spring) 27 that is compressed between the piston 18 of the lockup clutch 9 and the converter cover 5. .

  In the present embodiment, a release mechanism is provided for turning off the lock-up clutch 9 in the ON state according to the transmission torque. When the input members 11 and 12 and the output member 10 of the damper mechanism 8 are rotated relative to each other by the torque (input torque) of the electric motor 31 transmitted to the damper mechanism 8 via the lock-up clutch 9 in the ON state, the release mechanism. A cam mechanism for converting the relative rotation into an axial displacement of the piston member 28 is provided.

  Here, as shown in detail in FIG. 4, the piston member 28 has six pressing protrusions 28 </ b> B in the circumferential direction, etc. on one surface (the surface on the side facing the piston 18) of the ring plate-shaped main body 28 </ b> A. Projected integrally at an angular pitch (60 ° pitch), and four cams 28C projected integrally on the other surface (the surface facing the output member 10) at an equiangular pitch (90 ° pitch) in the circumferential direction. Configured. And this piston member 28 is formed in the inner peripheral part of one input member 11 in the notch-like engagement groove 28a formed between the adjacent thing of the press protrusion 28B protrudingly provided by this. The six claw-like engaging pieces 11a are engaged so as to rotate together with the input member 11. The six engaging pieces 11a formed on the input member 11 are arranged at an equiangular pitch (60 ° pitch) in the circumferential direction.

  On the other hand, as shown in FIG. 4, four cams 10 </ b> B are integrally formed at an equal angular pitch (90 ° pitch) around the center of the surface of the output member 10 of the damper mechanism 8 that faces the piston member 28. These cams 10B and the cams 28C projecting from the piston member 28 can be engaged with each other, and the cam mechanisms are constituted by these cams 10B and 28C. Each cam 28 </ b> C protruding from the piston member 28 and each cam 10 </ b> B protruding from the output member 10 are respectively formed with tapered cam surfaces 10 c. As shown in FIG. 2, the piston member 28 and the piston 18 are supported by a bearing (thrust bearing) 29 interposed therebetween so as to be relatively rotatable.

[Operation of torque converter]
Next, the operation of the torque converter 1 configured as described above will be described.

  In an electric vehicle, since the torque fluctuation of the electric motor 31 (see FIG. 1), which is a drive source, is small, a smooth start is possible. Therefore, at the time of start, the lockup clutch 9 is turned on (connected) and power loss due to slipping As described above, it is desirable to keep the value low.

  However, since the operating hydraulic pressure (lock-up ON hydraulic pressure) for turning on the lock-up clutch 9 is 0 or very low when the electric vehicle starts, the lock-up clutch 9 cannot be turned on conventionally.

  However, in the present embodiment, the spring 27 as a preload mechanism is mounted between the piston 18 of the lock-up clutch 9 and the converter cover 5 so that the spring 27 can be used even at the time of starting when sufficient operating oil pressure cannot be obtained. Since the piston 18 is pressed to the right in FIG. 1 and the friction clutch 19 is connected, the lockup clutch 9 is turned on, and the input shaft 32 of the electric motor 31 and the output shaft 33 connected to the speed reducer 40 shown in FIG. Is directly connected. That is, in the torque converter 1, the converter cover 5 that rotates together with the input shaft 32 of the electric motor 31 is transmitted directly to the output shaft 33 (without oil) through the lockup clutch 9 and the damper mechanism 8 in the ON state. Therefore, the power loss accompanying the slip (rotational speed difference) between the pump impeller 2 and the turbine runner 3 is kept low, and high power transmission efficiency is ensured. Here, the characteristics of the torque converter 1 according to the present embodiment are shown in FIG. 8. When the lockup clutch 9 is turned on (displayed as “LC ON” in FIG. 8) when the electric vehicle starts, Since the motor rotational speed (the rotational speed of the pump impeller 2) and the turbine rotational speed (the rotational speed of the turbine runner 3) are substantially the same, the power loss caused by the slippage between the pump impeller 2 and the turbine runner 3 is kept low. High power transmission efficiency is ensured. In the state where the lock-up clutch 9 is ON, the torque fluctuation of the electric motor 31 transmitted to the damper mechanism 8 is a compression coil spring due to the relative rotation between the input members 11 and 12 and the output member 10 in the damper mechanism 8. 13 is absorbed by elastic deformation.

  Then, when the electric vehicle is running with the lock-up clutch 9 turned on as described above, when the torque of the electric motor 31 (motor torque) exceeds a certain value as shown in FIG. The lock-up clutch 9 is turned off by the mechanism, and the turbine torque (torque transmitted to the output shaft 33) is increased by the torque amplification action by the torque converter 1.

  Here, the OFF operation of the lock-up clutch 9 due to the action of the cam mechanism provided in the release mechanism will be described with reference to FIGS.

  FIG. 7 is a diagram showing the relationship between the relative angle (damper twist angle) θ between the input members 11 and 12 and the output member 10 with respect to the input torque T to the damper mechanism 8, and when the input torque T is 0, FIG. As shown in FIG. 6 (a), no relative rotation (twist) occurs between the input member 11 (piston member 28) and the output member 10, and the relative angle θ between the input member 11 and the output member 10 at this time is 0. Then, when the input torque T rises to Tb shown in FIG. 7, relative rotation occurs between the input member 11 (piston member 28) and the output member 10, as shown in FIG. 6B. The relative angle θ between the input member 11 and the output member 10 is θb as shown in FIGS. 6B and 8.

  Even in the state shown in FIG. 6B, the cam 28C protruding from the piston member 28 and the cam 10B protruding from the output member 10 do not engage with each other, so the piston member 28 does not move in the axial direction. The lock-up clutch 9 is maintained in the ON state.

  When the input torque is further increased to Tc shown in FIG. 8, the relative rotation (twist) between the input member 11 (piston member 28) and the output member 10 in the damper mechanism 8 is further increased. The relative angle θ represents the value of θc shown in FIG. 6C and FIG. At this time, as shown in FIG. 6C, the cam 28C protruding from the piston member 28 and the cam 10B protruding from the output member 10 are engaged with each other. 6C, and the pressing protrusion 28B of the piston member 28 presses the piston 18 in the same direction via a bearing (thrust bearing) 29. As a result, since the piston 18 moves in the direction to turn off the lockup clutch 9, the lockup clutch 9 that was in the ON state is turned off, and the action of the torque converter 1 described below, as shown in FIG. The turbine torque is amplified with respect to the motor torque, and a large driving force is transmitted to the output shaft 33 shown in FIG. As shown in FIG. 8, when the lockup clutch 9 is in the OFF state (indicated as “LC OFF” in FIG. 8), there is a difference between the motor speed and the turbine speed. The power loss accompanying the slip of 2 and the turbine runner 3 generate | occur | produces. Here, in FIGS. 6B and 6C, the position before the relative rotation of the piston member 28 (the position shown in FIG. 6A) is indicated by a broken line.

  Here, the operation of the torque converter 1 when the lockup clutch 9 is in the OFF state will be described below.

  That is, when the lockup clutch 9 is in the OFF state, the pump impeller 2 connected to the input shaft 32 of the electric motor 31 shown in FIG. Then, the oil that rotates together with the pump impeller 2 due to viscosity is sent from the outer periphery of the pump impeller 2 toward the turbine runner 3 by centrifugal force, and this oil flows into the turbine runner 3 along the inner surface of the pump shell 2A. Since the oil flowing into the turbine runner 3 hits the plurality of turbine blades 3a, the turbine runner 3 is rotated by the inertial force, and the oil that has turned the turbine runner 3 is directed from the outer periphery toward the center. Even when it flows out, the turbine runner 3 is rotated by reaction force.

  Thereafter, the oil flowing out of the turbine runner 3 is changed in direction by the stator 4, flows from the center toward the pump impeller 2, rotates the pump impeller 2, and then wraps around the back surface of the pump impeller 2. Join the flow. By repeating such a series of oil flows, the torque transmitted from the pump impeller 2 to the turbine runner 3 is amplified, and the amplified torque is transmitted from the turbine runner 3 to the damper mechanism 8. The torque fluctuation of the electric motor 31 is absorbed by the mechanism 8. Note that while the rotational difference between the pump impeller 2 and the turbine impeller 3 is present, the stator 4 is stationary and performs a torque amplifying function. However, when the rotational speed of the pump impeller 2 and the turbine impeller 3 approaches, the torque amplification by the stator 4 The effect is reduced and the stator 4 rotates (idling) together with the turbine runner 3 by the action of the one-way clutch 6 in order to prevent the flow of oil.

  As described above, when torque is transmitted to the damper mechanism 8, the torque is transmitted from the output member 10 of the damper mechanism 8 to the output shaft 33 shown in FIG. The rotation of the output shaft 33 is transmitted to the left and right axles 51 through the speed reducer 40 and the differential device 50 of the electric motor unit 30 shown in FIG. 1, and the left and right drive wheels 60 attached to the left and right axles 51 are rotationally driven. Is done.

  As described above, according to the torque converter 1 according to the present embodiment, the lockup clutch 9 is turned on by the pressurizing mechanism configured by the spring 27 at the time of low torque when the electric vehicle starts, The power loss accompanying the slip at the start can be kept low. In addition, since a release mechanism that turns off the lock-up clutch 9 in the ON state according to the transmission torque is provided, the lock-up clutch 9 is turned off by the release mechanism when a large driving force is required in a high load range. A large driving force can be obtained by amplifying the torque by the torque amplifying action of the torque converter 1. As a result, it is possible to achieve both the reduction of power loss due to slippage at the start of the electric vehicle and the securing of the necessary driving force at the time of high load.

  In the above embodiment, the pressurizing mechanism is configured by the spring (coil spring) 27, but any means other than the spring 27 can be used for the pressurizing mechanism.

  Further, in the above embodiment, as the release mechanism for turning off the lockup clutch 9 in the high load range, the relative rotation due to the input torque between the input member 11 and the output member 10 in the damper mechanism 8 is changed in the axial direction of the piston member 28. Although a mechanism using a cam mechanism that converts to the above is employed, any other mechanism can be used as long as the lock-up clutch 9 is turned off in a high load range.

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

DESCRIPTION OF SYMBOLS 1 Torque converter 2 Pump impeller 3 Turbine runner 4 Stator 5 Converter cover 6 One-way clutch 8 Damper mechanism 9 Lock-up clutch 10 Output member 10A Output member flange part 10B Output member cam 11, 12 Input member 13 Compression coil spring (power transmission) Elastic member)
15, 16 Connecting pin 18 Piston 19 Friction clutch 27 Spring (Pressurizing mechanism)
28 Piston member 28A Piston member main body 28B Piston member pressing projection 28C Piston member cam 30 Electric motor drive unit 31 Electric motor 32 Input shaft 33 Output shaft 40 Reduction gear 50 Differential device 60 Drive wheel

Claims (5)

It is arranged between the electric motor and the speed reducer of the electric motor drive unit mounted on the electric vehicle,
The pump impeller connected to the input shaft of the electric motor and the turbine runner connected to the output shaft to the speed reducer are arranged to face each other, and a stator is arranged between the pump impeller and the turbine runner and operated. A lock-up clutch that directly connects the input shaft and the output shaft under a predetermined condition by being turned ON / OFF by hydraulic pressure, and a damper mechanism provided between the turbine runner and the output shaft are provided, and torque is internally provided. In an electric vehicle torque converter configured by filling oil as a transmission medium,
A pressurizing mechanism for turning on the lockup clutch at a low torque when the electric vehicle starts,
A release mechanism that turns off the lock-up clutch in an ON state according to a transmission torque;
The torque converter for electric vehicles characterized by providing. The lock-up clutch includes a piston that is slid by operating hydraulic pressure to turn the lock-up clutch on / off,
The torque converter for an electric vehicle according to claim 1, wherein the pressurizing mechanism is configured by a spring that biases the piston in a direction in which the lockup clutch is turned on. The damper mechanism is elastically deformed by an output member coupled to the output shaft, an input member relatively rotatable with respect to the output member within a predetermined angle range, and relative rotation of the input member and the output member. Comprising an elastic member for power transmission that absorbs torque fluctuations,
The torque converter for an electric vehicle according to claim 2, wherein the release mechanism includes a cam mechanism that converts relative rotation of the input member and the output member of the damper mechanism into sliding of the piston.   The cam mechanism engages with the input member, rotates together with the input member, and engages a cam formed on a piston member movable in the axial direction and a cam formed on the output member. The torque converter for an electric vehicle according to claim 3, wherein the torque converter is configured as described above.   5. The electric vehicle according to claim 1, wherein the release mechanism turns off the lock-up clutch in an ON state when it is necessary to amplify a transmission torque in a high load range. Torque converter.