KR20230082121A - two-speed transmission for electric vehicles - Google Patents

Abstract

A two-speed transmission for an electric vehicle includes an input unit including an input shaft having a first-stage input gear and a second-stage input gear, a first-stage output gear meshed with the first-stage input gear, and a second-stage output gear meshed with the second-stage input gear. an output unit including an output shaft to do, and a first-speed shift in which rotational output by a combination of the first-stage input gear and the first-stage output gear is transmitted to the output shaft, and the second-stage input gear and the second-stage output gear and a shift actuator configured to selectively implement a two-speed shift in which a rotational output by a combination of is transmitted to the output shaft. The shift actuator includes a drive shaft configured to be rotatable, a first gear shift fork and a second gear shift fork fastened to the drive shaft to linearly move in response to rotation of the drive shaft, and a linear movement of the first gear shift fork. The rotation of the first-stage output gear is selectively transmitted to the output shaft by the linear movement of the first-stage clutch and the second-stage shift fork acting to selectively transmit the rotation of the first-stage output gear to the output shaft. It includes a two-stage clutch that

Description

Two-speed transmission for electric vehicles}

The present invention relates to a transmission for an electric vehicle, and more particularly, to a two-speed transmission for an electric vehicle capable of realizing two transmission ratios.

Conventional internal combustion engines for automobiles are rapidly being replaced by electric motors, and automobiles using electric motors as a power source are generally referred to as electric vehicles. An electric vehicle may include a pure electric vehicle using a battery charged by an external power source as a power source, a hydrogen electric vehicle using a reaction between hydrogen and oxygen as an energy source, and the like.

Batteries that store energy to drive an electric motor account for a large percentage of the production cost of an electric vehicle, and thus the performance and capacity of the battery are very important factors in optimizing the power unit of an electric vehicle. However, despite numerous technology developments for reducing production costs and improving performance of batteries, due to limitations in battery technology, measures to improve battery operation efficiency through optimized design and control of power units are being discussed. One of these measures is to replace the existing 1-speed reducer of an electric vehicle with a 2-speed gearbox. Through the application of the two-speed transmission, battery capacity and cost can be reduced, as well as fuel efficiency and drivability can be improved.

However, since the transmission for electric vehicles is recognized as an inexpensive power transmission system that does not have torque converters, valve bodies, clutches, satellite gears, etc., which are parts of conventional transmissions, there are many restrictions on the use of two-speed transmissions to improve motor driving efficiency. . In order to realize an inexpensive two-speed transmission, it is necessary to minimize the number of transmission parts in consideration of the characteristics of an electric vehicle, and it is required to minimize the number of parts of a two-speed transmission through structural optimization design or functional integration design.

Korean Patent Registration No. 10-2103565 (2020.04.16.)

The problem to be solved by the present invention is to provide a two-speed transmission for an electric vehicle with a small number of parts.

A two-speed transmission for an electric vehicle according to an embodiment of the present invention includes an input unit including an input shaft having a first-stage input gear and a second-stage input gear, a first-stage output gear meshed with the first-stage input gear, and a second-stage input gear. An output unit including an output shaft having an engaged second-stage output gear, and a first-stage shift in which a rotational output generated by a combination of the first-stage input gear and the first-stage output gear is transmitted to the output shaft, and the second-stage input and a shift actuator configured to selectively realize a two-speed shift in which a rotational output generated by a combination of a gear and the second-stage output gear is transmitted to the output shaft. The shift actuator includes a drive shaft configured to be rotatable, a first gear shift fork and a second gear shift fork fastened to the drive shaft to linearly move in response to rotation of the drive shaft, and a linear movement of the first gear shift fork. The rotation of the first-stage output gear is selectively transmitted to the output shaft by the linear movement of the first-stage clutch and the second-stage shift fork acting to selectively transmit the rotation of the first-stage output gear to the output shaft. It includes a two-stage clutch that

The first gear shift fork and the second gear shift fork may be coupled to the drive shaft by a cylindrical cam structure to linearly move in a direction parallel to an axial direction of the output shaft in response to rotation of the drive shaft.

The drive shaft may include a first-stage drive groove and a second-stage drive groove. The first-stage shift fork may include a driving protrusion movably inserted into the first-stage driving groove, and the second-stage shift fork may include a driving protrusion movably inserted into the second-stage driving groove.

The first-stage clutch and the second-stage clutch may be respectively fastened to the output shaft so as to be relatively movable with respect to the output shaft along an axial direction of the output shaft while rotating together with the output shaft. The 2-stage clutch moves linearly together with the 1-stage shift fork and the 2-stage shift fork to provide rotational power by a combination of the 1-stage input gear and the 1-stage output gear or the rotational power of the 2-stage input gear and the 2-stage output gear. The rotational power of the combination can be selectively actuated to be transmitted to the output shaft.

The output shaft may include fastening teeth for engaging the first-stage clutch and the second-stage clutch, and the first-stage clutch and the second-stage clutch may each include a fastening groove engaged with the fastening teeth.

The first-stage output gear may include a first-stage connection gear that rotates together, and the second-stage output gear may include a second-stage connection gear that rotates together. The first-stage clutch may include a first-stage fastening tooth configured to selectively engage with the first-stage connection gear in response to movement of the output shaft in an axial direction, and the second-stage clutch may include an axis of the output shaft It may include a two-stage fastening tooth configured to be selectively engaged with the two-stage connection gear in response to movement in the direction.

The first-stage clutch and the second-stage clutch may each have fastening grooves provided on outer circumferential surfaces, and the first-stage shift fork and the second-stage shift fork are respectively inserted into the fastening grooves of the first-stage clutch and the second-stage clutch. Each fastening protrusion may be provided.

The first-stage clutch and the second-stage clutch may be dog clutches.

According to the present invention, a two-speed transmission for an electric vehicle having a reduced number of parts and an optimized structure can be provided.

1 is a perspective view showing the configuration of a two-speed transmission for an electric vehicle according to an embodiment of the present invention.
2 is a view showing engagement of a shift fork and a dog clutch of a two-speed transmission for an electric vehicle according to an embodiment of the present invention.
3 is a view showing engagement of a dog clutch and an input shaft of a two-speed transmission for an electric vehicle according to an embodiment of the present invention.
4 is a cross-sectional view of a dog clutch of a two-speed transmission for an electric vehicle according to an embodiment of the present invention.
5 is an exploded perspective view of an input shaft and a shift actuator of a two-speed transmission for an electric vehicle according to an embodiment of the present invention.
6 is a view showing a drive shaft of a shift actuator according to an embodiment of the present invention.
7 is a diagram showing a power transmission route in a first gear shift state of a two-speed transmission for an electric vehicle according to an embodiment of the present invention.
8 is a diagram showing a power transmission route in a 2-speed shift state of a 2-speed transmission for an electric vehicle according to an embodiment of the present invention.

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

Referring to FIG. 1, a two-speed transmission according to an embodiment of the present invention includes an input unit 10 that receives the output of a motor 1, an output unit 20 that receives power from the input unit 10, and a first or It includes a shift actuator 30 that operates to implement a two-speed transmission ratio.

The input unit 10 may include an input shaft 11 that rotates in the axial direction X1 by the output of the motor 1, and the input shaft 11 includes a first-stage input gear 12 that rotates together. and a two-stage input gear 13. The first-stage input gear 12 and the second-stage input gear 13 may be spur gears, and the second-stage input gear 13 may be formed to have larger or more teeth than the first-stage input gear 12 . Meanwhile, the input shaft 11 may be rotatably supported by a transmission case (not shown) through bearings 14 and 15 .

The output unit 20 may include an output shaft 21 disposed parallel to the input shaft 11 . The output shaft 21 is configured to be rotatable around an axial direction X2 parallel to the axial direction X1 of the input shaft 11, and the output shaft 21 has a first stage output gear 22 and a second stage. An output gear 23 may be provided. The first-stage output gear 22 meshes with the first-stage input gear 12, and the second-stage output gear 23 meshes with the second-stage input gear 13. The first stage output gear 22 and the second stage output gear 23 may be spur gears, and the first stage output gear 22 may be formed to have larger or more teeth than the second stage output gear 23 . Meanwhile, the output shaft 21 may be rotatably supported on the transmission case by bearings 24 and 25 . Furthermore, the output unit 20 may have a final output gear 26 provided on the output shaft 21 to rotate together with the output shaft 21, and the final output gear 26 is attached to the differential gear 41. interlock to transmit the output.

2 to 5, the first-stage output gear 22 and the second-stage output gear 23 are configured to relatively rotate without transmitting rotational force to the output shaft 21, and the shift actuator 30 ) is configured so that the rotational force of the first-stage output gear 22 or the second-stage output gear 23 can be selectively transmitted to the output shaft 21. When the input shaft 11 rotates by the operation of the motor 1, the first stage input gear 12 and the second stage input gear 13 rotate together with the input shaft 11, and the first stage output gear 22 And the second-stage output gear 23 also meshes with the first-stage input gear 12 and the second-stage input gear 13 to rotate. The shift actuator 30 operates so that the first-stage output gear 22 and the output shaft 21 rotate together to achieve a first-stage shift, or the second-stage output gear 23 and the output shaft 21 rotate together to It can be operated so that a two-speed shift is achieved.

The shift actuator 30 transmits the rotational output by the combination of the first-stage input gear 12 and the second-stage output gear 22 to the output shaft 21, and the second-stage input gear 13 and 2 It is configured to selectively implement a two-speed shift in which rotational output by the combination of the single output gears 23 is transmitted to the output shaft 21 . As described above, the shift actuator 30 engages the first stage output gear 22 and the output shaft 21 in a state of being rotationally restrained with respect to each other, or the second stage output gear 23 and the output shaft 21 are fastened in a rotationally constrained state with respect to each other. The variable speed actuator 30 includes a drive shaft 31 configured to be rotatable about an axial direction X3 parallel to an axial direction X2 of the output shaft 21, and the drive shaft 31 is driven by a motor It is rotatably arranged around the axial direction (X3) by a separate actuator such as (not shown). The drive shaft 31 may be rotatably supported by bearings 32 and 33 .

On the other hand, the shift actuator 30 is a first gear shift fork 34 coupled to the drive shaft 31 and a second gear shift fork 34 coupled to the drive shaft 31 to linearly move along the axial direction of the output shaft 21 in response to rotation of the drive shaft 31. It includes a shifting fork 35. The 1st gear shift fork 34 and the 2nd gear shift fork 35 are fastened to the drive shaft 31 to independently linearly move in the axial direction of the output shaft 21 in response to the rotation of the drive shaft 31. .

For example, the first gear shift fork 34 and the second gear shift fork 35 may be coupled to the drive shaft 31 through a cylindrical cam structure. The drive shaft 31 is installed to pass through through-holes 321 and 331 respectively provided in the first gear shift fork 34 and the second gear shift fork 35 . The drive shaft 31 has a first drive groove 311 and a second drive groove 312, and the first gear shift fork 34 and the second gear shift fork 35 have first and second drive grooves 311 , 312 are provided with insertion protrusions 341 and 351, respectively. In the first drive groove 311 and the second drive groove 312, the insertion protrusions 341 and 351 move in the first and second drive grooves 311 and 312 in response to the rotation of the drive shaft 31, and The position along the axial direction of the drive shaft 31 is formed to have a variable profile so as to cause linear movement of the first and second gear shift forks 34 and 35 .

The first-stage dog clutch 36 moves in a direction parallel to the axial direction X2 together with the first-stage shift fork 34 when the first-stage shift fork 34 moves in a direction parallel to the axial direction X2 of the output shaft 21. It is fastened to the first gear shift fork 34 to move to . Accordingly, rotation of the drive shaft 31 about the axial direction X3 causes a linear movement of the first gearshift fork 34 and the output shaft X2 of the first gear dock clutch 36 in the axial direction. . Similarly, the second-speed dock clutch 37 moves in the axial direction (X2) together with the second-speed shift fork 35 when the second-speed shift fork 35 moves in a direction parallel to the axial direction (X2) of the output shaft 21. It is fastened to the 2-speed shift fork 35 so as to move in a direction parallel to the . Thereby, rotation of the drive shaft 31 about the axial direction X3 causes a linear movement of the output shaft X2 of the second gearshift fork 35 and the second gear dock clutch 37 in the axial direction. . The movement of the output shafts 21 of the first-stage dog clutch 36 and the second-stage dog clutch 37 in a direction parallel to the axial direction X2 is implemented as a first-stage shift or a second-stage shift. The first-stage dog clutch 36 and the second-stage dog clutch 37 are disposed between the first-stage output gear 22 and the second-stage output gear 23 . The first-stage dog clutch 36 is disposed near the first-stage output gear 22, and the second-stage dog clutch 37 is disposed near the second-stage output gear 23.

2 and 5, the 1st and 2nd gear shift forks 34 and 35 have first fastening parts 341 and 351 fastened to the drive shaft 31, and the 1st gear dog clutch 36 and 2 However, second fastening parts 344 and 354 respectively fastened to the dog clutch 37 are included. The first fastening parts 341 and 351 form through holes 342 and 352 into which the drive shaft 31 is inserted, and the second fastening parts 344 and 354 extend from the first fastening parts 341 and 351. and are fastened to the first and second stage dog clutches 36 and 37, respectively. The first fastening parts 341 and 351 may have a ring shape forming the through holes 342 and 352, and drive protrusions 343 and 353 inserted into the drive grooves 311 and 312 of the drive shaft 31, respectively. ) are provided, respectively. The second fastening parts 344 and 354 may have a substantially C-shape, and fastening protrusions 345 inserted into fastening grooves 361 and 371 formed on outer circumferential surfaces of the first and second-stage dog clutches 36 and 37, respectively. , 355), respectively.

The output unit 20 includes first and second stage connection gears 27 and 28 for selective engagement with the first and second stage dog clutches 34 and 35 . The first-stage connection gear 27 may be integrally formed with the first-stage output gear 22 so as to rotate together with the first-stage output gear 22, and the second-stage connection gear 28 is formed with the second-stage output gear 23 It may be integrally formed with the second stage output gear 23 to rotate together.

4 and 5, the first and second-stage dog clutches 36 and 37 may have a ring shape to allow the output shaft 21 to pass through, and the first and second-stage dog clutches 36 and 37 ) is fastened to the output shaft 21 so as to be movable in the axial direction X2 of the output shaft 21 and rotated together with the output shaft 21 around the axial direction X2. For example, the output shaft 21 has fastening teeth 211 extending parallel to the axial direction X2 on the outer circumferential surface, and the first and second stage dog clutches 36 and 37 are of the output shaft 21. Fastening grooves 362 and 372 into which the fastening teeth 211 are inserted are respectively provided. Through engagement of the tooth 211 of the output shaft 21 and the fastening grooves 362 and 372 of the first and second stage dog clutches 36 and 37, the first and second stage dog clutches 36 and 37 are As such, it can move relative to the output shaft 21 in the axial direction X2 and at the same time rotate with the output shaft 21 on the other hand. At this time, even when the first and second-stage dog clutches 36 and 37 move relative to the output shaft 21 in the axial direction (X2), the fastening grooves 362 and 372 maintain engagement with the fastening teeth 211. is configured to

On the other hand, the first-stage dog clutch 36 may be engaged or separated from the first-stage connecting gear 27 rotating together with the first-stage output gear 22 according to the position in the axial direction X2 with respect to the output shaft 21. The second-stage dog clutch 37 meshes with the second-stage connection gear 28 rotating together with the second-stage output gear 23 according to the position in the axial direction (X2) with respect to the output shaft 21. It is configured so that it can be removed or separated. Referring to FIG. 4, the first-stage dog clutch 36 has a first-stage fastening tooth 363 configured to engage with the first-stage connection gear 27, and the second-stage dog clutch 37 has a second-stage connection. A two-stage fastening tooth 373 configured to engage with the gear 28 may be provided.

6 is a view showing the shapes of the drive grooves 311 and 312 of the drive shaft 31 for realizing the linear movement of the first and second stage shift forks 34 and 35 as described above. Figures 6 (a) to (h) sequentially show the state rotated by 45 degrees. Referring to FIG. 6 , as the drive shaft 31 rotates, the positions of the insertion protrusions 341 and 351 of the first and second gear shift forks 34 and 35 in the axial direction X3 are changed. The positions of the output shafts 21 of the first and second gear shift forks 34 and 35 in the axial direction X2 can be changed. For example, in the state (a) of FIG. 6, the first gear shift fork 34 and the second gear shift fork 35 are located farthest from the first gear output gear 22 and the second gear output gear 23, Both the single-stage dog clutch 36 and the second-stage dog clutch 37 may be separated from the first-stage connection gear 27 and the second-stage connection gear 28 . For example, in the state of FIG. 6 (c), the first-stage shift fork 34 and the first-stage dog clutch 36 fastened thereto are located close to the first-stage output gear 22, so that the first-stage dog clutch 36 ) can be engaged with the first-stage connection gear 27, and the second-stage shift fork 35 and the second-stage dog clutch 37 fastened thereto are located far from the second-stage output gear 23, so that the second-stage dog clutch ( 36) can be separated from the second stage connecting gear (28). For example, in the state of FIG. 6 (d), the first-stage shift fork 34 and the first-stage dog clutch 36 fastened thereto are located far from the first-stage output gear 22, so that the first-stage dog clutch 36 ) can be separated from the first-stage connection gear 27, and the second-stage shift fork 35 and the second-stage dog clutch 37 fastened thereto are located close to the second-stage output gear 23, so that the second-stage dog clutch ( 36) may be meshed with the second stage connecting gear 28. Meanwhile, in the state of FIG. 6 (f), the first-stage dog clutch 36 may be engaged with the first-stage connection gear 27 and the second-stage dog clutch 37 may be engaged with the second-stage connection gear 28.

FIG. 7 shows a state in which the first-stage shift fork 34 approaches the first-stage output gear 22 and the first-stage shift is realized. In the state of FIG. 7 , the first-stage dog clutch 36 is engaged with the first-stage connecting gear 27 to form the first-stage input gear 12, the first-stage output gear 22, the first-stage dog clutch 36, and the output shaft 31 Through ), the output shifted to one gear is transmitted to the final output gear 26 and the differential gear 41. As a result, a single-speed shift having a power transmission route indicated by an arrow in FIG. 7 can be implemented. Further, FIG. 8 shows a state in which the second-stage shifting fork 35 approaches the second-stage output gear 23 and realizes a second-stage shift. In the state of FIG. 8 , the second-stage dog clutch 37 is engaged with the second-stage connection gear 28 to form the second-stage input gear 13, the second-stage output gear 23, the second-stage dog clutch 37, and the output shaft 31. ), the two-speed shifted output is transmitted to the final output gear 26 and the differential gear 41. As a result, a two-speed shift having a power transmission route indicated by an arrow in FIG. 8 can be implemented. Meanwhile, in order to implement the parking state, the first-stage dog clutch 36 may be engaged with the first-stage connection gear 27 and the second-stage dog clutch 37 may be engaged with the second-stage connection gear 28. As a result, the transmission is in a locking state, and a parking state may be created.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also within the scope of the present invention. belong

1: motor
10: input unit
20: output unit
30: shift actuator
11: input shaft
12: 1st stage input gear
13: 2nd gear input gear
14, 15: bearing
21: output shaft
22: 1st stage output gear
23: second stage output gear
24, 25: bearing
31: drive shaft
34: 1st shift fork
35: 2-speed fork
36: 1st stage dog clutch
37: 2-speed dog clutch
41: differential gear

Claims (8)

An input unit including an input shaft having a first-stage input gear and a second-stage input gear;
An output unit including an output shaft having a first-stage output gear meshed with the first-stage input gear and a second-stage output gear meshed with the second-stage input gear, and
A first-speed shift in which a rotational output generated by a combination of the first-stage input gear and the first-stage output gear is transmitted to the output shaft, and a rotational output generated by a combination of the second-stage input gear and the second-stage output gear is transmitted to the output shaft. A shift actuator configured to selectively implement a two-speed shift transmitted to
including,
The variable speed actuator
a drive shaft configured to be rotatable;
A first gear shift fork and a second gear shift fork fastened to the drive shaft to linearly move in response to rotation of the drive shaft;
A first-stage clutch acting to selectively transmit the rotation of the first-stage output gear to the output shaft by the linear movement of the first-stage shift fork; and
A 2-stage clutch acting to selectively transmit the rotation of the 2-stage output gear to the output shaft by the linear movement of the 2-stage shift fork.
Two-speed transmission for electric vehicles including a. In paragraph 1,
The first gear shift fork and the second gear shift fork are respectively fastened to the drive shaft by a cylindrical cam structure to linearly move in a direction parallel to the axial direction of the output shaft in response to rotation of the drive shaft. single gearbox. In paragraph 2,
The drive shaft has a first-stage drive groove and a second-stage drive groove,
The first-stage shift fork has a driving protrusion movably inserted into the first-stage driving groove,
The second-stage shift fork has a driving protrusion movably inserted into the second-stage driving groove
Two-speed gearbox for electric vehicles. In paragraph 1,
The first-stage clutch and the second-stage clutch are respectively fastened to the output shaft so as to move relative to the output shaft along the axial direction of the output shaft while rotating together with the output shaft;
The first-stage clutch and the second-stage clutch linearly move together with the first-stage shifting fork and the second-stage shifting fork, thereby providing rotational power by a combination of the first-stage input gear and the first-stage output gear or the second-stage input gear and the second-stage clutch. Operating so that the rotational power by the combination of the two-stage output gear is selectively transmitted to the output shaft
Two-speed gearbox for trains. In paragraph 4,
The output shaft has fastening teeth for fastening with the first-stage clutch and the second-stage clutch,
The first-stage clutch and the second-stage clutch each have a fastening groove engaged with the fastening tooth.
Two-speed gearbox for electric vehicles. In paragraph 5,
The first-stage output gear includes a first-stage connection gear that rotates together,
The two-stage output gear includes a two-stage connection gear that rotates together,
The first-stage clutch includes a first-stage fastening tooth configured to selectively engage with the first-stage connection gear in response to movement of the output shaft in an axial direction,
The second-stage clutch includes a second-stage fastening tooth configured to selectively engage with the second-stage connection gear in response to movement of the output shaft in the axial direction.
Two-speed gearbox for trains. In paragraph 1,
The first-stage clutch and the second-stage clutch each have a fastening groove provided on an outer circumferential surface,
The first gear shift fork and the second gear shift fork each have fastening protrusions respectively inserted into the fastening grooves of the first gear clutch and the second gear clutch.
Two-speed gearbox for electric vehicles. In paragraph 1,
The first-stage clutch and the second-stage clutch are dog clutches.

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