CN116710681A

CN116710681A - Speed change structure for electric drive device of vehicle and electric drive device comprising same

Info

Publication number: CN116710681A
Application number: CN202180088879.8A
Authority: CN
Inventors: 金兑根; 孙重洛; 郑铭澈
Original assignee: Yilai Automotive Electronic Chassis System Co ltd
Current assignee: Yilai Automotive Electronic Chassis System Co ltd
Priority date: 2020-12-30
Filing date: 2021-12-27
Publication date: 2023-09-05
Also published as: KR102284191B1

Abstract

An electric drive device includes: a housing; an electric motor including a motor shaft rotatably supported by the housing; a speed change unit that reduces a rotational speed generated by a rotational driving force of the motor shaft; and a double clutch unit configured to receive the rotational driving force transmitted from the speed change unit and to selectively rotationally drive the pair of output shafts. The speed change unit includes: an input gear that receives a rotational driving force of a motor shaft; a shift shaft rotatably supported by the housing; an output gear provided on the shift shaft to rotate together with the shift shaft; and a clutch unit operative to enable selective engagement between the input gear and the shift shaft due to rotational constraint.

Description

Speed change structure for electric drive device of vehicle and electric drive device comprising same

Technical Field

The present invention relates to an electric drive apparatus for transmitting power of an electric machine such as a motor.

Background

An electric motor such as a motor is used as a power source in place of or in addition to a conventional internal combustion engine, and a vehicle employing such an electric motor as a power source is called an electric vehicle or a hybrid vehicle.

When a motor is used as a power source, a reduction device for reducing the rotational speed of the rotational power of the motor is required. Since the motor can adjust the rotation speed, an electric drive device realized as a single-stage reduction device is sometimes used, but an electric drive device capable of performing two-stage reduction for improving efficiency has also been employed. Such an electric drive may be configured to perform a torque vectoring function capable of independent adjustment of the torque transmitted to the two drive wheels.

However, the conventional electric drive device has a problem in that the overall size of the device is large and the structure is complicated because it uses complicated and heavy parts such as planetary gears to achieve the speed reduction and torque vector distribution functions. Further, there is a need for improvements in the structural aspects of the device, increasing ease of manufacture, and reducing manufacturing costs by optimizing the arrangement of the rotating shaft and bearings therein.

< prior art document >

U.S. patent No. 10,493,978 (12 months 3 days 2019);

U.S. patent No. 10,753,405 (8 months 25 days 2020).

Disclosure of Invention

[ technical problem ]

The invention aims to provide an electric driving device with two-stage speed reduction and torque vector distribution functions, which is simple in structure and easy to manufacture.

Technical scheme

According to an embodiment of the present invention, a transmission structure for reducing a rotational speed of a rotational driving force of an electric drive apparatus having a motor shaft includes: an input gear that receives a rotational driving force of a motor shaft; a shift shaft rotatably mounted about a rotation axis; an output gear provided on the shift shaft to rotate together with the shift shaft; and a clutch unit operable to selectively effect rotation-constrained engagement between the input gear and the shift shaft.

The clutch unit may include: a piston configured to be moved along the rotation axis by hydraulic force; a clutch plate assembly configured to selectively transmit rotation of the input gear to the shift shaft; and a force transmitting member that moves by a movement of the piston and transmits a force acting on the piston to the clutch plate assembly. The force transfer member may be coupled to the input gear to rotate with the input gear while being movable along the rotational axis.

The piston and clutch plate assemblies may be disposed on either side of the input gear along the rotational axis. The force transmitting member may include: a main body portion disposed between the piston and the input gear; and a protrusion protruding from the main body portion in a direction parallel to the rotation axis and passing through a through hole formed in the input gear to be exposed into a space where the clutch plate assembly is located.

According to another embodiment of the present invention, the clutch unit may include: a piston configured to be moved along the rotation axis by hydraulic force; a clutch housing coupled to the shift shaft in a state of being rotationally constrained to rotate together with the shift shaft; a clutch hub coupled to the input gear in a state of being rotationally constrained to rotate together with the input gear; a clutch plate assembly operable to selectively effect rotational constraint engagement between the clutch housing and the clutch hub; and a force transmitting member configured to transmit a force for operating the clutch plate assembly to the clutch plate assembly in response to movement of the piston.

The clutch hub may be integrally formed with the input gear, and the clutch plate assembly may include outer and inner plates disposed alternately with each other. The outer plate may be coupled to the clutch housing so as to be movable along the rotational axis and rotationally constrained, and the inner plate may be coupled to the clutch hub so as to be movable along the rotational axis and rotationally constrained.

The clutch unit may further include a return spring that provides a force for returning the force transmitting member that is moved toward the clutch plate assembly by the movement of the piston.

The return spring may be configured to elastically support the force transmitting member with respect to the input gear.

The clutch unit may further include a snap ring coupled to the protrusion to limit a return movement of the force transmitting member by the return spring.

The speed change structure according to another embodiment of the present invention may further include a sleeve member coupled to the speed change shaft, and the input gear may be rotatably supported by the sleeve member via a needle bearing.

The clutch unit may include: a clutch plate assembly configured to effect rotational constrained engagement between the input gear and the shift shaft; a piston that moves along the rotational axis by hydraulic pressure to generate a force for operating the clutch plate assembly; a force transmitting member configured to transmit a force for operating the clutch plate assembly to the clutch plate assembly in response to movement of the piston; and a return spring providing a force for returning the force transmitting member that is moved toward the clutch plate assembly by the movement of the piston.

The clutch unit may further include: a clutch housing coupled to the shift shaft in a state of being rotationally constrained to rotate together with the shift shaft; and a clutch hub coupled to the input gear in a rotation-constrained state to rotate with the input gear. The clutch plate assembly is operable to selectively form a rotation-restricting engagement between the clutch housing and the clutch hub.

An electric drive device according to an embodiment of the present invention includes: a housing; an electric motor including a motor shaft rotatably supported by the housing; a speed change unit for reducing the rotational speed of the rotational driving force of the motor shaft; and a double clutch unit configured to selectively rotationally drive the pair of output shafts by receiving a rotational driving force of the speed change unit. The speed change unit includes: an input gear that receives a rotational driving force of a motor shaft; a shift shaft rotatably supported by the housing; an output gear provided on the shift shaft to rotate together with the shift shaft; and a clutch unit operable to selectively effect rotation-constrained engagement between the input gear and the shift shaft.

[ Effect of the invention ]

According to the present invention, the rotational driving force of the motor shaft is selectively transmitted through the clutch unit mounted in the input gear of the speed change unit engaged with the motor shaft, thereby simplifying the structure of the speed change unit and reducing the number of parts.

Drawings

Fig. 1 shows a cross-sectional view of an electric drive according to an embodiment of the invention.

Fig. 2 shows a perspective view of a first reduction unit of an electric drive according to an embodiment of the invention.

Fig. 3 is a cross-sectional view taken along line III-III of fig. 2.

Fig. 4 shows an exploded perspective view of a first reduction unit of an electric drive according to an embodiment of the invention.

Fig. 5 shows a perspective view of the first reduction unit, the second reduction unit and the double clutch unit of the electric drive according to an embodiment of the invention.

Fig. 6 shows a perspective view of a dual clutch unit of an electric drive according to an embodiment of the invention.

Fig. 7 is a sectional view taken along line VI-VI of fig. 5.

Fig. 8 shows a partial cross-sectional view of the dual clutch unit and housing of the electric drive according to an embodiment of the invention.

Fig. 9 shows an exploded perspective view of a dual clutch unit of an electric drive device according to an embodiment of the invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the present invention. The invention may, however, be embodied in many different forms and is not limited to the embodiments described.

The electric drive device 1 may be configured to drive a drive shaft of a vehicle. The electric drive apparatus 1 may be used as an apparatus for driving a vehicle independently, or may be applied to a vehicle using an existing internal combustion engine as a power source and used as an apparatus for driving a vehicle together with the internal combustion engine.

Fig. 1 shows a cross-sectional view of an electric drive according to an embodiment of the invention. Fig. 1 is a sectional view of an electric driving apparatus according to an embodiment of the present invention cut along V-shaped cutting lines connecting three rotation axes X1, X2, and X3. Referring to fig. 1, an electric drive apparatus 1 according to an embodiment of the present invention includes a speed change unit 2 rotatably driven by an electric motor such as a motor 200, and a double clutch unit 3 rotatably driven by the speed change unit. The double clutch unit can be driven by means of actuators 4 and 5, respectively. The electric drive 1 may further comprise a housing 6 accommodating the gear unit 2 and the double clutch unit 3.

The motor may include a stator and a rotatable rotor. The rotor is configured to be rotated by applying an electric current supplied from a battery of the vehicle, and is connected to the motor shaft 7 in a power transmission manner to rotationally drive the motor shaft 7. Although not specified in the drawings, the motor shaft 7 may be arranged coaxially with the motor and may be coupled to an output element of the motor to be rotationally driven about the rotation axis X1 by the output element of the motor. For example, the motor shaft 7 may be connected to an output element of the motor by gear coupling, spline coupling, or the like.

Although not shown in fig. 1, the housing 6 may further include a housing for accommodating a motor on the right side of the housing 6 shown in fig. 1, and the motor shaft 7 may be rotatably supported on the housing 6 through a bearing. The housing 6 may include a first housing 11 and a second housing 12 fastened to each other, and the first housing 11 and the second housing 12 may be fastened to each other by separate fastening members or they may be fastened to each other by means such as welding.

The rotational movement of the motor shaft 7 is transmitted to the double clutch unit 3 via the transmission unit 2. That is, the rotational driving force of the motor is transmitted to the double clutch unit 3 through the motor shaft 7 and the speed change unit 2, and the double clutch unit 3 is configured to distribute the transmitted torque and to transmit the distributed torque to the two output shafts 8 and 9. Further, the output shafts 8 and 9 may be connected to side shafts (not shown) connected to driving wheels of the vehicle via constant velocity joints (not shown), respectively.

The motor shaft 7 may be configured as a hollow shaft having a through hole 13 extending in the longitudinal direction, and may be supported on the housing 6 by a bearing so as to be rotatable about the rotation axis X1. One output shaft 8 of the two output shafts 8 and 9 may be coaxially arranged in a through hole 13 of the motor shaft 7, and in this respect, the electric drive 1 according to an embodiment of the present invention may be referred to as coaxial.

A drive gear 14 is provided on the motor shaft 7 to rotate together with the motor shaft 7. The drive gear 14 extends in an annular shape in the circumferential direction of the motor shaft 7, whereby the drive gear 14 can rotate around the rotation axis X1 together with the motor shaft 7.

According to an embodiment of the present invention, the speed change unit 2 includes a first speed reduction portion 15 and a second speed reduction portion 16. The first and second speed reducers 15 and 16 are configured to reduce the rotational speed of the motor shaft 7 at different rotational speeds and transmit it to the double clutch unit 3. The first reduction portion 15 and the second reduction portion 16 can realize shifting by a gear device that reduces the rotation speed through gear tooth engagement.

The first reduction section 15 includes an input gear 17, a speed change shaft 18, and an output gear 19, and similarly, the second reduction section 16 also includes an input gear 21, a speed change shaft 22, and an output gear 23.

The input gears 17 and 21 are engaged with the drive gear 14, respectively, and are rotationally driven by the drive gear 14. The shift shafts 18 and 22 are provided in the housing 6 to be rotatable about rotation axes X2 and X3 extending parallel to the rotation axis X1 of the motor shaft 7, respectively. As shown in fig. 1, the speed change shafts 18 and 22 are inserted into the through hole 23 of the input gear 17 and the through hole 24 of the input gear 21 to be arranged coaxially with the input gears 17 and 21. The shift shafts 18 and 22 are rotatably supported on the housing 6 through bearings such as tapered roller bearings 81, 82, 83 and 84. Referring to fig. 1 and 4, the tapered roller bearing 82 may be supported on the housing 6 by a support ring 87. Needle bearings 25 and 26 are interposed between the input gears 17 and 21 and the speed change shafts 18 and 22 to allow the input gears 17 and 21 and the speed change shafts 18 and 22 to perform relative rotation. Referring to fig. 1 and 4, the sleeve member 88 may be fastened to the shift shaft 18, and the needle bearing 25 is disposed between the sleeve member 88 and the input gear 17 such that the input gear 17 may be rotatably supported on the shift shaft 18.

The input gears 17 and 21 are configured to be selectively rotationally fixed to the shift shafts 18 and 22 via clutch units 27 and 28. That is, when the clutch units 27 and 28 are in the operating state, that is, in a state in which the rotational force is transmitted, the rotation of the input gears 17 and 21 is transmitted to the speed change shafts 18 and 22 through the clutch units 27 and 28, and when the clutch units 27 and 28 are in a state in which the rotational force is not transmitted, the input gears 17 and 21 rotate together with the drive gear 14 without rotating the speed change shafts 18 and 22.

The two clutch units 27 and 28 provided in the first and second speed reducing portions 15 and 16, respectively, have the same structure and function in the same manner. The clutch units 27 and 28 may be configured to be operable by hydraulic pressure. Referring to fig. 1 to 3, the clutch units 27 and 28 include clutch housings 29 and 33, clutch hubs 30 and 34, force transmitting members 31 and 35, pistons 32 and 36, and clutch plate assemblies 42 and 43, respectively. Further, the clutch units 27 and 28 may further include axial bearings 37 and 39 provided between the force transmitting members 31 and 35 and the pistons 32 and 36 for rotatably supporting the force transmitting members 31 and 35, and return springs 38 and 89 for returning the force transmitting members 31 and 35.

The pistons 32 and 36 may have annular shapes, and may be movably disposed in the axial directions X2 and X3 in annular hydraulic chambers 40 and 41 formed in the housing 6, which may be supplied with hydraulic pressure.

The force transmitting member 31 transmits an axial force generated by the movement of the piston 32 to the clutch plate assembly 42 provided in the clutch housing 29. As shown in fig. 4, the force transmitting member 31 may include a main body portion 49 having a shape of an annular disk facing the piston 32, and a plurality of protrusions 50 axially protruding from an inner end portion of the main body portion 49.

Referring to fig. 3 and 4, the clutch plate assembly 42 includes a plurality of outer plates 44 and a plurality of inner plates 45 alternately arranged in the axial direction (i.e., in the direction of the rotational axis X2). The outer plate 44 is axially movable and circumferentially constrained to the clutch housing 29, and the inner plate 45 is axially movable and circumferentially constrained to the clutch hub 30. Similarly, the clutch plate assembly 43 of the second reduction gear portion 16 also includes a plurality of outer plates secured to the clutch housing 33 and a plurality of inner plates secured to the clutch hub.

The clutch hubs 30 and 34 may be fixedly secured to the input gear 17 or integrally formed with the input gear 17 to rotate with the input gear 17 about the rotational axis X2, and the clutch housings 29 and 30 may be fixedly secured to the shift shaft 18 to rotate with the shift shaft 18 about the rotational axis X2.

A plurality of protrusions 50 may be arranged at equal intervals in the circumferential direction on the surface of the main body portion 49, and each protrusion 50 penetrates an axial through hole 52 formed in the input gear 17 to extend to a space where the clutch plate assembly 42 within the clutch housing 29 is located. The force transmitting member 31 is fastened to the input gear 17 by a protrusion 50 fastened to an axial through hole 52 of the input gear 17 to rotate together with the input gear 17. Meanwhile, the force transmitting member 31 is configured to be movable in the axial direction X2 with respect to the input gear 17 to transmit the axial force of the piston 32 to the clutch plate assembly 42 provided in the clutch housing 29. At this time, the protrusion 50 of the force transmitting member 31 may be configured to act on the pressing piece 48 axially movably provided in the clutch housing 29 adjacent to the clutch plate assembly 42. Meanwhile, the other side of the clutch plate assembly 42 may be supported on a support plate 47 supported in the axial direction by an axial bearing 46 supported on the clutch housing 29.

When hydraulic pressure is supplied to the hydraulic chamber 40, axial movement of the piston 32 (leftward movement in fig. 3) occurs, and the axial movement of the piston 32 causes axial movement of the force transmitting member 31, thereby causing the protrusion 50 of the force transmitting member 31 to press the clutch plate assembly 42. When the clutch plate assembly 42 is pressed, the outer plate 44 and the inner plate 45 are in contact such that the clutch hub 30 and the clutch housing 29 rotate together about the rotational axis X2. Thus, the shift shaft 18 can rotate together with the input gear 17.

The return spring 38 returns the force transmitting member 31 relative to the input gear 17 in a direction away from the clutch plate assembly 42. The return spring 38 may be a leaf spring that elastically supports the force transmitting member 31 with respect to the input gear 17. At this time, a snap ring 51 for restricting the return movement of the force transmitting member 31 may be fastened to the protrusion 50 of the force transmitting member 31. As shown in fig. 1 and 3, the snap ring 51 fastened to the protrusion 50 of the force transmission member 31 is in contact with the input gear 17, so that an additional returning operation of the force transmission member 31 can be prevented.

The output gears 19 and 23 are fastened to the speed change shafts 18 and 22 in a rotationally fixed state to rotate together with the speed change shafts 18 and 22. The output gears 19 and 23 may be integrally formed as part of the shift shafts 18 and 22, or may be separately formed and fastened to the shift shafts 18 and 22. The output gears 19 and 23 may be ring gears formed on the outer peripheral surfaces of the shift shafts 18 and 22 in the circumferential direction, and may be integrally formed with the shift shafts 18 and 22. Referring to fig. 1 and 5, the output gears 19 and 23 are engaged with two ring gears 54 and 55 provided in a clutch housing 56 of the double clutch unit 3, respectively, to drive the double clutch unit 3. Accordingly, the clutch housing 56 serving as an input element of the double clutch unit 3 can be rotated by the rotation of the shift shafts 18 and 22. At this time, the output gears 19 and 23 of the speed change shafts 18 and 22 and the ring gears 54 and 55 of the clutch unit 3 engaged therewith may include helical teeth and may be configured to have a gear ratio for achieving desired deceleration.

According to the embodiment of the present invention, it can be seen that two reduction ratios can be achieved by the speed change unit 2. The first reduction portion 15 and the second reduction portion 16 each have one shift shaft 18 and 23 and two gear pairs. The first reduction portion 15 is a first gear pair having a first gear ratio by engagement of the drive gear 14 of the motor shaft 7 with the input gear 17, and is a second gear pair having a second gear ratio by engagement of the output gear 19 of the shift shaft 18 with the ring gear 54 of the double clutch unit 3. At this time, the input gear 17 of the first reduction portion 15 has more gear teeth than the drive gear 14 of the motor shaft 7 to achieve the first gear ratio of the predetermined reduction ratio, and the ring gear 54 of the double clutch unit 3 also has more gear teeth than the output gear 19 of the speed change shaft 18 to achieve the second gear ratio of the predetermined reduction ratio. Therefore, the first reduction portion 15 achieves a final speed ratio by a combination of the first speed ratio and the second speed ratio. Similarly, the second reduction portion 16 achieves a final speed ratio having two speed ratios, that is, a first speed ratio achieved by engagement of the drive gear 14 of the motor shaft 7 with the input gear 21 and a second speed ratio achieved by engagement of the output gear 23 of the speed change shaft 22 with the ring gear 55 of the double clutch unit 3. At this time, the input gear 17 of the first reduction portion 15 and the input gear 21 of the second reduction portion 16 may have the same number of gear teeth, and the output gear 19 of the first reduction portion 15 may have fewer gear teeth than the output gear 23 of the second reduction portion 16, and the ring gear 54 of the double clutch unit 3 engaged with the output gear 19 of the first reduction portion 15 may have more gear teeth than the ring gear 55 of the double clutch unit 3 engaged with the output gear 23 of the second reduction portion 16. Due to this number of gear teeth, the first reduction portion 15 has a larger reduction ratio than the second reduction portion 16. The reduction ratio of the first reduction gear portion 15 and the second reduction gear portion 16 may be appropriately set as needed.

The double clutch unit 3 may comprise two clutches, each of which may be operated independently. Referring to fig. 1 and 5 to 7, the double clutch unit 3 includes a clutch housing 56 as an input element and two clutch hubs, i.e., a first clutch hub 57 and a second clutch hub 58, as an output element. The first clutch hub 57 is coupled to the first output shaft 8 in a rotationally fixed manner, and the first output shaft 8 transmits the applied torque to a side shaft (not shown) through a constant velocity joint (not shown). Similarly, the second clutch hub 58 may be coupled to the second output shaft 9 in a rotationally fixed manner. The two clutch hubs 57 and 58 can be rotatably supported to each other about the rotation axis X1 by means of an axial bearing 129. The axial bearing 129 has an annular shape and may be interposed between the clutch hubs 57 and 58 to rotatably support the clutch hubs 57 and 58 relative to each other.

The above-described two ring gears 54 and 55 are formed on the outer peripheral surface of the clutch housing 56, and the clutch housing 56 receives rotational driving force from the speed change shafts 18 and 22 via the two ring gears 54 and 55. The clutch housing 56 is supported by clutch bearings 59 and 60 for rotational drive by the shift shafts 18 and 22. The clutch bearings 59 and 60 may be implemented as tapered roller bearings configured to support axial forces while allowing them to be introduced into the housing 6.

Torque may be transferred from the clutch housing 56 to the first clutch hub 57 and the second clutch hub 58 via two clutch plate assemblies (first clutch plate assembly 64 and second clutch plate assembly 65, respectively). The clutch plate assemblies 64 and 65 each include a plurality of outer plates 66 and a plurality of inner plates 67 alternately arranged in the axial direction (i.e., in the direction of the rotational axis X1). The outer and inner sheets 66, 67 may each have an annular disc shape. The outer plate 66 is connected to the clutch housing 56 so as to be axially movable and constrained in the circumferential direction (e.g., in a spline-coupled manner), and the inner plate 67 is connected to the clutch hubs 57 and 58 so as to be axially movable and constrained in the circumferential direction (e.g., in a spline-coupled manner). The double clutch unit 3 may be coaxially arranged with respect to the motor, and the clutch housing 56 is rotatably supported within the housing 6 by means of clutch bearings 59 and 60 in a state coaxial with the rotation axis X1 of the motor shaft 7. The first clutch hub 57 and the second clutch hub 58, which rotate with the first output shaft 8 and the second output shaft 9, respectively, are rotatably supported by the clutch housing 56 by means of radial bearings 85 and 86 rotatable relative to the clutch housing 56.

The clutch housing 56 includes a first clutch housing 61 and a second clutch housing 62 disposed to face each other, and the first clutch housing 61 and the second clutch housing 62 are fastened to each other by a fastening bolt 63 to rotate together about the rotation axis X1. The fastening bolts 63 extend in a direction parallel to the rotation axis X1 and may be provided in plurality. Since the two clutch housings 61 and 62 are in close contact with each other in the axial direction and are fastened by the fastening bolts 63, concentricity of the two clutch housings 61 and 62 can be improved.

The first clutch housing 61 and the second clutch housing 62 are arranged coaxially with the first output shaft 8 and the second output shaft 9. The first and second clutch housings 61 and 62 are fastened to each other to form a substantially cylindrical space, and the clutch hubs 57 and 58 and the clutch plate assemblies 64 and 65 are disposed in the space formed by the first and second clutch housings 61 and 62.

As shown in fig. 5 to 7, the first clutch housing 61 and the second clutch housing 62 include ring gears 54 and 55 respectively engaged with the output gear 19 of the first reduction portion 15 and the output gear 22 of the second reduction portion 16, respectively. The two ring gears 54 and 55 are each arranged coaxially with the rotation axis X1 and may have different sizes and/or numbers of teeth. When the clutch unit 27 of the first reduction portion 15 or the clutch unit 28 of the second reduction portion 16 is in the power transmission state, rotational power is transmitted to one of the ring gears 54 and 55 of the two clutch housings 61 and 62, and the first clutch housing 61 and the second clutch housing 62 fastened to each other to rotate together are rotated together by the transmitted rotational power. When at least one of the two clutch plate assemblies 64 and 65 of the double clutch unit 3 is in a power transmission state in a state in which the clutch housings 61 and 62 are rotated, rotational power is output through at least one of the first output shaft 8 and the second output shaft 9.

Referring to fig. 1 and 7, the first clutch housing 61 includes a clutch coupling portion 68 coupled with the outer clutch plate 66 and a cover portion 69 extending radially inward from an end portion (right end portion in fig. 7) of the clutch fastening portion 68, and may further include a sleeve portion 70 axially protruding from an inner end portion of the cover portion 69. The clutch coupling portion 68 and the cover portion 69 form a space in which the clutch plate assembly 64 is disposed, and the sleeve portion 70 forms a through hole through which the first output shaft 8 passes. The ring gear 54 engaged with the output gear 19 of the first reduction gear portion 15 may be formed on the outer peripheral surface of the clutch coupling portion 68. In addition, the second clutch housing 62 includes a clutch coupling portion 71 coupled with the outer clutch plate 66 and a cover portion 72 extending radially inward from an end portion (left end portion in fig. 7) of the clutch coupling portion 71, and may further include a sleeve 73 axially protruding from an inner end portion of the cover portion 72. The clutch coupling portion 71 and the cover portion 72 form a space in which the clutch plate assembly 65 is disposed, and the sleeve portion 73 forms a through hole through which the second output shaft 9 passes. The sleeve portion 70 of the first clutch housing 61 and the sleeve portion 73 of the second clutch housing 62 are rotatably supported by the clutch bearings 59 and 60, respectively.

The two clutches of the double clutch unit 3 can be operated independently by two actuators 4 and 5, respectively. For this purpose, the two actuators 4 and 5 can be controlled independently by a hydraulic circuit controlled by a control unit (not shown), whereby the torque transmitted to the first clutch hub 57 via the second clutch plate assembly 65 can be variably set independently of each other. Thus, so-called torque vectoring is achieved, which can vary the torque of each driving wheel. The two actuators 4 and 5 are disposed outside the first clutch housing 61 and the second clutch housing 62, respectively, in the axial direction, and are supported in opposite directions along the rotation axis X1 with respect to the structure constituting the housing 6. Since the two actuators 4 and 5 are identical in structure and operation, only one actuator will be described below.

The force transmitting members 101 and 102 transmit the axial force generated by the actuators 4 and 5 to the clutch plate assemblies 64 and 65 provided in the clutch housings 61 and 62. The force transmitting members 101 and 102 are configured to be movable in the axial direction X1 by the axial force generated by the actuators 4 and 5. Referring to fig. 7, 8 and 9, the force transmitting members 101 and 102 include disc-shaped body portions 103 and 104 facing the cover portions 69 and 72 of the clutch housings 61 and 62, and a plurality of protrusions 105 and 106 protruding from the body portions 103 and 104 in the axial direction. The plurality of protrusions 105 and 106 may be arranged at equal intervals in the circumferential direction on the surfaces of the body portions 103 and 104, and the protrusions 105 and 106 each extend into the space where the clutch plate assemblies 64 and 65 in the clutch housings 61 and 62 are located through axial through holes 107 and 108 formed in the cover portions 69 and 72 of the clutch housings 61 and 62. The force transmitting members 101 and 102 are coupled to the clutch housings 61 and 62 by protrusions 105 and 106 inserted into axial through holes 107 and 108 of the clutch housings 61 and 62 to rotate together with the clutch housings 61 and 62. Further, the force transmitting members 101 and 102 are configured to be axially movable with respect to the clutch housings 61 and 62 to transmit the axial force of the actuators 4 and 5 provided outside the clutch housings 61 and 62 to the clutch plate assemblies 64 and 65 provided inside the clutch housings 61 and 62.

The protrusions 105 and 106 of the force transmitting members 101 and 102 are configured to act on the tabs 109 and 110 axially movably disposed within the clutch housing 61 and 62 adjacent the clutch plate assemblies 64 and 65. Meanwhile, the reaction plate 111 is installed to be positioned between the two clutch plate assemblies 64 and 65 in the clutch housing 56 in a state of preventing axial movement. The reaction plate 111 may have the shape of an annular disk, and the radially outer end is inserted into an annular groove 112 formed between the first clutch housing 61 and the second clutch housing 62 to prevent axial movement thereof. The clutch plate assemblies 64 and 65, which are respectively disposed on both sides of the reaction plate 111, are supported by the reaction plate 111 in the axial direction.

The actuators 4 and 5 may be implemented as hydraulic actuators, and the actuators 4 and 5 each include pistons 113 and 114 movable in the axial direction X1 by hydraulic pressure. The piston denoted by reference numeral 113 is urged by hydraulic force to move to the left in fig. 7 in the axial direction X1, and the piston denoted by reference numeral 114 is urged by hydraulic force to move to the right in fig. 7 in the axial direction X1. The pistons 113 and 114 may have an annular shape as a whole, and may be disposed in annular cylinder chambers 115 and 116 formed in the housing 6, as shown in fig. 1. Pistons 113 and 114 may be axially supported via support plates 119 and 120 on retaining rings 117 and 118 secured to clutch housing 6. Hydraulic passages 121 and 122 for supplying hydraulic pressure to the spaces between the pistons 113 and 114 and the support plates 119 and 120 may be formed in the clutch housing 6. The pistons 113 and 114 can be moved toward the clutch housings 61 and 62 in the axial direction X1 by hydraulic pressure supplied into the spaces between the support plates 119 and 120 and the pistons 113 and 114.

The axial bearings 123 and 124 are interposed between the pistons 113 and 114 and the force transmitting members 101 and 102 in an axially movable state, and the axial force of the pistons 113 and 114 is transmitted to the force transmitting members 101 and 102 through the axial bearings 123 and 124. As the pistons 113 and 114 move toward the clutch housings 61 and 62, the axial bearings 123 and 124 and the force transmitting members 101 and 102 are pushed by the pistons 113 and 114 to move together in the axial direction.

When the actuators 4 and 5 are not operated, i.e., when hydraulic pressure is not supplied to the space between the pistons 113 and 114 and the support plates 119 and 120, the return springs 127 and 128 may be provided for returning the pistons 113 and 114 away from the clutch housings 61 and 62. Referring to fig. 1 and 8, return springs 127 and 128 resiliently support pistons 113 and 114 relative to the clutch housing, and in particular relative to piston housings 131 and 132, to apply a force to pistons 113 and 114 to urge pistons 113 and 114 away from clutch housings 61 and 62. When the actuators 4 and 5 are not operated, the pistons 113 and 114 are separated from the force transmission members 101 and 102 by the elastic restoring forces of the return springs 127 and 128, so that no axial force is applied to the force transmission members 101 and 102. As shown in fig. 1 and 8, the return springs 127 and 128 may be leaf springs that elastically support the pistons 113 and 114 with respect to the piston housings 131 and 132 in a direction away from the clutch housings 61 and 62. Fig. 7 and 8 show a state in which the pistons 113 and 114 are urged by the elastic restoring forces of the return springs 127 and 128 and are in close contact with the support plates 119 and 120, in which the pistons 113 and 114 do not transmit axial force to the force transmitting members 101 and 102. Meanwhile, when hydraulic pressure is supplied to the space between the support plates 119 and 120 and the pistons 113 and 114, the pistons 113 and 114 move toward the clutch housings 61 and 62 while compressing the return springs 127 and 128 toward the clutch housings 61 and 62 to move the force transmitting members 101 and 102. Accordingly, the force transmitting members 101 and 102 press the clutch plate assemblies 64 and 65 so that the clutch operates.

Referring to fig. 8, clutch hubs 57 and 58 may include outer sleeves 141 and 142, inner sleeves 143 and 144, and connection portions 145 and 146 connecting outer sleeves 141 and 142 with inner sleeves 143 and 144. Outer sleeves 141 and 142 may extend parallel to axial direction X1 to have a hollow cylindrical shape, and clutch plate assemblies 64 and 65 may be coupled to outer circumferential surfaces of outer sleeves 141 and 142. Inner sleeves 143 and 144 may extend parallel to axial direction X1 at the radially inner sides of outer sleeves 141 and 142 to have a hollow cylindrical shape. Referring to fig. 1 and 7, the inner sleeves 143 and 144 form axial through holes into which the output shafts 8 and 9 are inserted, and spline structures 171 and 172 for spline-coupling with the output shafts 8 and 9 may be formed on the inner circumferences of the inner sleeves 143 and 144. The clutch hubs 57 and 58 and the output shafts 8 and 9 are rotated together about the rotation axis X1 by spline coupling. The radial bearings 85 and 86 rotatably support the outer peripheral surfaces of the inner sleeves 143 and 144 and the clutch housings 61 and 62 relative to each other, thereby allowing the clutch housings 61 and 62 to relatively rotate with the clutch hubs 57 and 58. The connecting portions 145 and 146 extend in the radial direction to connect one end portions of the outer sleeves 141 and 142 and one end portions of the inner sleeves 143 and 144. The connection portions 145 and 146 of the two clutch hubs 57 and 58 are disposed to face each other, and the axial bearing 129 is disposed to be supported by the two connection portions 145 and 146, respectively. This allows the two clutch hubs 57 and 58 to rotate relative to each other and to rotate independently.

According to an embodiment of the present invention, pistons 113 and 114 are configured to increase the effective area of hydraulic force action without increasing the axial and radial length of the electric drive. Referring to fig. 8 and 9, the pistons 113 and 114 have annular main body portions 151 and 153 and a plurality of protrusions 152 and 154 extending from radially outer edge regions in parallel with the axial direction X1. The outer surfaces in the axial direction of the body portions 151 and 153 facing the support plates 119 and 120 are surfaces on which hydraulic force acts, and the protrusions 152 and 154 are portions that perform the function of transmitting axial force to the force transmitting members 101 and 102 through the bearings 123 and 124. Since the protruding portions 152 and 154 protrude from the edge regions of the main body portions 151 and 153, the effective area of the hydraulic force action of the main body portions 151 and 153 can be sufficiently obtained.

Referring to fig. 8, the piston housings 131 and 132 include first axial extensions 161 and 162, radial extensions 163 and 164, and second axial extensions 165 and 166. The first axial extensions 161 and 162 and the second axial extensions 165 and 166 extend along the axial direction X1 at different radial positions, respectively. As shown in fig. 8, the second axial extension portions 165 and 166 extend along the axial direction X1 at radial positions farther from the axial direction X1 than the first axial extension portions 161 and 162 (i.e., at positions farther from the axial direction X1), and the radial extension portions 163 and 164 extend in the radial direction to connect one end portions of the first axial extension portions 161 and 162 and one end portions of the second axial extension portions 165 and 166. Referring to fig. 8, the first axial extension portions 161 and 162 face radially inner end portions of the body portions 151 and 152 of the pistons 113 and 114, and the radial extension portions 163 and 164 face axially side portions of the body portions 151 and 152 of the pistons 113 and 114. Further, the second axial extensions 165 and 166 face the radially inner ends of the protrusions 152 and 154 of the pistons 113 and 114. Due to the shape and arrangement of the pistons 113 and 114 and the piston housings 131 and 132, an inner space in the radial direction of the second axial extensions 165 and 166 of the piston housings 131 and 132 can be utilized, and in the embodiment of the present invention, as shown in fig. 8, the clutch bearings 59 and 60 supporting the clutch housings 161 and 162 are provided in the space.

More specifically, the second axial extension portions 165 and 166 of the piston housings 131 and 132 are disposed radially outward of the sleeve portions 70 and 73 of the clutch housings 57 and 58, while the second axial extension portions 165 and 166 of the housings 131 and 132 are disposed at least partially overlapping the sleeve portions 70 and 73 of the clutch housings 57 and 58 in the axial direction. As a result, annular bearing accommodation spaces 181 and 182 are formed between the second axial extension portions 165 and 166 of the piston housings 131 and 132 and the sleeve portions 70 and 73 of the clutch housings 57 and 58, and the clutch bearings 59 and 60 are disposed in the bearing accommodation spaces 181 and 182, respectively. Accordingly, as shown in fig. 7 and the like, the clutch bearings 59 and 60 are provided in the radially inner spaces of the projections 153 and 154 of the pistons 113 and 114 and the force transmitting members 101 and 102, and the radial dimensions of the entire system can be reduced accordingly. At this time, the clutch bearings 59 and 60 may be tapered roller bearings, and the tapered roller bearings 59 and 60 are radially supported by the sleeve portions 70 and 73 of the clutch housings 57 and 58 and the second axial extension portions 165 and 166 of the piston housings 131 and 132 and simultaneously axially supported by the cover portions 69 and 70 of the clutch housings 57 and 58 and the radial extension portions 163 and 164 of the piston housings 131 and 132, respectively. With this structure, a sufficiently effective area of the pistons 113 and 114 for applying hydraulic pressure can be obtained, and a space for the clutch bearings 59 and 60 to support the clutch housings 57 and 58 can be obtained without significantly increasing the radial and axial dimensions of the entire device.

In addition, as shown in fig. 8, the radially inner peripheral surfaces of the body portions 103 and 104 of the force transmitting members 101 and 102 and the radially inner peripheral surfaces of the axial bearings 123 and 124 interposed between the pistons 113 and 114 and the force transmitting members 101 and 102 are provided to face the outer peripheral surfaces of the second axial extensions 165 and 166 of the piston housings 131 and 132. A compact structure is obtained due to the structure and arrangement of the piston housings 131 and 132, the pistons 113 and 114, the bearings 123 and 124, and the force transmission members 101 and 102.

While the invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[ Industrial applicability ]

The present invention can be applied to an electric drive device of a vehicle, and thus has industrial applicability.

Claims

1. A transmission structure for reducing a rotational speed of a rotational driving force of an electric drive apparatus having a motor shaft, comprising:

an input gear that receives a rotational driving force of the motor shaft;

a shift shaft rotatably mounted about a rotation axis;

an output gear provided on the shift shaft to rotate together with the shift shaft; and

A clutch unit operable to selectively effect rotation-constrained engagement between the input gear and the shift shaft.

2. The transmission structure according to claim 1, wherein the clutch unit includes: a piston configured to be moved along the rotational axis by hydraulic force; a clutch plate assembly configured to selectively transmit rotation of the input gear to the shift shaft; and a force transmission member that moves by the movement of the piston and transmits a force acting on the piston to the clutch plate assembly, and

wherein the force transfer member is coupled to the input gear to rotate with the input gear while being movable along the rotational axis.

3. The transmission structure according to claim 2, wherein the piston and the clutch plate assembly are disposed on both sides of the input gear along the rotational axis, respectively, and wherein the force transmitting member includes: a main body portion provided between the piston and the input gear; and a protrusion protruding from the main body portion in a direction parallel to the rotation axis and passing through a through hole formed in the input gear to be exposed into a space where the clutch plate assembly is located.

4. The transmission structure according to claim 1, wherein the clutch unit includes:

a piston configured to be moved along the rotational axis by hydraulic force;

a clutch housing coupled to the shift shaft in a state of being rotationally constrained to rotate together with the shift shaft;

a clutch hub coupled to the input gear in a state of being rotationally constrained to rotate together with the input gear;

a clutch plate assembly operable to selectively effect rotational constraint engagement between the clutch housing and the clutch hub; and

a force transmitting member configured to transmit a force for operating the clutch plate assembly to the clutch plate assembly in response to movement of the piston.

5. The transmission structure of claim 4, wherein the clutch hub is integrally formed with the input gear, wherein the clutch plate assembly includes outer and inner plates disposed alternating with one another, wherein the outer plates are coupled to the clutch housing so as to be movable along the rotational axis and rotationally constrained, and wherein the inner plates are coupled to the clutch hub so as to be movable along the rotational axis and rotationally constrained.

6. The transmission structure of claim 5, wherein the clutch unit further includes a return spring that provides a force for returning the force transmitting member that is moved toward the clutch plate assembly by movement of the piston.

7. The shifting structure of claim 6, wherein the return spring is configured to resiliently support the force transmitting member relative to the input gear.

8. The transmission structure according to claim 4, wherein the piston and the clutch plate assembly are disposed on both sides of the input gear, respectively, along the rotation axis, and

wherein the force transmitting member comprises: a main body portion provided between the piston and the input gear; and a protrusion protruding from the main body portion in a direction parallel to the rotation axis and passing through a through hole formed in the input gear to be exposed into a space where the clutch plate assembly is located.

9. The transmission structure of claim 8, wherein the clutch unit further includes a return spring that provides a force for returning the force transmitting member that is moved toward the clutch plate assembly by movement of the piston.

10. The transmission structure of claim 9, wherein the clutch unit further includes a snap ring coupled to the protrusion to limit return movement of the force transmitting member by the return spring.

11. The transmission structure of claim 4, further comprising a sleeve member coupled to the shift shaft, wherein the input gear is rotatably supported by the sleeve member via a needle bearing.

12. The transmission structure according to claim 1, wherein the clutch unit includes:

a clutch plate assembly configured to effect rotational constrained engagement between the input gear and the shift shaft;

a piston that moves along the rotational axis by hydraulic force to generate a force for operating the clutch plate assembly;

a force transmitting member configured to transmit a force for operating the clutch plate assembly to the clutch plate assembly in response to movement of the piston; and

a return spring providing a force for returning the force transmitting member moved toward the clutch plate assembly by the movement of the piston.

13. The transmission structure according to claim 12, wherein the clutch unit further includes:

A clutch housing coupled to the shift shaft in a state of being rotationally constrained to rotate together with the shift shaft; and

a clutch hub coupled to the input gear in a state of being rotationally constrained to rotate together with the input gear, an

Wherein the clutch plate assembly is operative to selectively form a rotation-restricting engagement between the clutch housing and the clutch hub.

14. An electric drive apparatus, comprising:

a housing;

an electric motor including a motor shaft rotatably supported by the housing;

a speed change unit for reducing a rotational speed of a rotational driving force of the motor shaft; and

a double clutch unit configured to selectively rotationally drive a pair of output shafts by receiving a rotational driving force of the speed change unit,

wherein the speed change unit includes:

an input gear that receives a rotational driving force of the motor shaft;

a shift shaft rotatably supported by the housing;

15. The electric drive of claim 14, wherein the clutch unit comprises: a piston configured to be moved along the rotational axis by hydraulic force; a clutch plate assembly configured to selectively transmit rotation of the input gear to the shift shaft; and a force transmission member that moves by the movement of the piston and transmits a force acting on the piston to the clutch plate assembly, and

16. The electric drive of claim 15, wherein the piston and the clutch plate assembly are disposed on both sides of the input gear along the rotational axis, respectively, and wherein the force transfer member comprises: a main body portion provided between the piston and the input gear; and a protrusion protruding from the main body portion in a direction parallel to the rotation axis and passing through a through hole formed in the input gear to be exposed into a space where the clutch plate assembly is located.

17. The electric drive of claim 14, wherein the clutch unit comprises:

A piston configured to be moved along the rotational axis by hydraulic force;

18. The electric drive of claim 17, wherein the clutch hub is integrally formed with the input gear, wherein the clutch plate assembly includes outer and inner plates disposed alternating with one another, wherein the outer plates are coupled to the clutch housing so as to be movable along the rotational axis and rotationally constrained, and wherein the inner plates are coupled to the clutch hub so as to be movable along the rotational axis and rotationally constrained.

19. The electric drive of claim 18 wherein the clutch unit further comprises a return spring providing a force for returning the force transmitting member that is moved toward the clutch plate assembly by movement of the piston.

20. The electric drive of claim 17, wherein the piston and clutch plate assembly are disposed on both sides of the input gear along the rotational axis, respectively, and

21. The electric drive of claim 14, wherein the clutch unit comprises:

22. The electric drive of claim 21, wherein the clutch unit further comprises: