Power transmission system of electric vehicle

Abstract

The present invention provides a power transmission system of an electric vehicle, the power transmission system having first, second, third, and fourth planetary gear sets mounted inside a case so as for power to be interconnected, and first gear being shifted by a sleeve moving in the first gear shift direction to restrain a first carrier of the first planetary gear set, or second gear being shifted by the sleeve moving in the second gear shift direction to restrain a first sun gear of the first planetary gear set, or third gear being shifted by the sleeve moving in the third gear shift direction to be engaged simultaneously with the first sun gear and a first ring gear of the first planetary gear set.

Description

Power transmission system of an electric vehicle

[0001] The present invention relates to a power transmission device for an electric vehicle.

[0002] The demand for electric vehicles (fuel cell vehicles) for commercial vehicles, such as freight trucks and buses, is increasing due to exhaust gas regulations and the reduction of fossil energy consumption.

[0003] In electric vehicles, the power from the drive motor can be transmitted to the drive wheels through the reduction gear and the axle.

[0004] Conventional power electric (PE) systems of electric vehicles can be classified into a central motor type, which receives power from a drive motor and transmits it to the axle through a reduction gear, and an electric axle (E-Axle) type, which includes a drive motor, a reduction gear, and a differential gear for the axle.

[0005] Compared to internal combustion engine vehicles, conventional electric vehicles require the Power Electric (PE) system—which combines the motor, inverter, and reduction gear—to be more compact due to factors such as the increased installation space for the battery pack.

[0006] However, conventional electric vehicles had difficulty meeting the required performance with 1st and 2nd stage reduction gears due to the power train layout characteristics of the electric axle (E-Axle). In addition, when high-performance drive motors were applied, there were problems such as occupying a large amount of mounting space and increasing costs.

[0007] [Prior Art Literature]

[0008] [Patent Literature]

[0009] (Patent Document 1) Korean Published Patent Application No. 10-2007-0076773 (Published July 25, 2007)

[0010] To solve the aforementioned problem, the present invention aims to provide a power transmission device for an electric vehicle that facilitates easy installation in a vehicle package due to a reduction structure composed of a plurality of planetary gear sets.

[0011] To achieve the aforementioned objective, the present invention provides a power transmission device for an electric vehicle characterized in that a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set are mounted inside a case so as to be connected to each other by power, and a sleeve moves in the first gear shift direction to restrain the first carrier of the first planetary gear set to achieve a first gear shift, or a sleeve moves in the second gear shift direction to restrain the first sun gear of the first planetary gear set to achieve a second gear shift, or a sleeve moves in the third gear shift direction to mesh simultaneously with the first sun gear and the first ring gear of the first planetary gear set to achieve a third gear shift.

[0012] Additionally, the first planetary gear set comprises a first sun gear having a hub, an external gear having an external gear on the outer diameter of the hub, a first planetary gear arranged along the circumference of the external gear, and a first ring gear surrounding the first planetary gear, wherein the first planetary gear is engaged externally to the first planetary gear between the first sun gear and the first ring gear, and simultaneously engaged internally to the first ring gear, and the second planetary gear set comprises a second sun gear provided on a motor shaft and a second planetary gear arranged along the circumference of the second sun gear, wherein the second planetary gear is engaged externally to the second sun gear between the second sun gear and the first planetary gear, and simultaneously engaged externally to the first planetary gear, and the third planetary gear set comprises a third sun gear connected to the first ring gear, and the of the third sun gear It includes a third planetary gear arranged along the circumference and a second ring gear surrounding the third planetary gear, wherein the third planetary gear is engaged externally with the third sun gear and simultaneously engaged internally with the second ring gear between the third sun gear and the second ring gear, and the fourth planetary gear set includes a fourth sun gear provided on the outer diameter of the second ring gear, a fourth planetary gear arranged along the circumference of the fourth sun gear, and a third ring gear surrounding the fourth planetary gear, wherein the fourth planetary gear can be engaged externally with the fourth sun gear and simultaneously engaged internally with the third ring gear between the fourth sun gear and the third ring gear.

[0013] Additionally, the third carrier is fixed to the case, and the first planetary gear is rotatably connected to the first carrier, and the first carrier is positioned between the first sun gear and the first ring gear, and the third planetary gear is rotatably connected to the second carrier, and the second carrier is connected to the intershaft, and the fourth planetary gear can be rotatably connected to the third carrier.

[0014] Additionally, a sleeve is mounted inside the case, and one of a 1st gear, 2nd gear, and 3rd gear shift is achieved by the operation of the sleeve, and the sleeve may include a first meshing part provided on the outer diameter portion; a second meshing part provided on one side of the inner diameter portion; and a third meshing part provided on the other side of the inner diameter portion.

[0015] Additionally, when shifting to the first gear, as the sleeve moves in the direction of shifting to the first gear, the first meshing part may be engaged with the fourth meshing part provided in the case, and the second meshing part may be engaged with the fifth meshing part provided in the outer diameter of the first carrier.

[0016] Additionally, when shifting to the second gear, as the sleeve moves in the direction of shifting to the second gear, the first meshing part may mesh with the fourth meshing part, and the second meshing part may mesh with the sixth meshing part provided on the outer diameter of the first sun gear.

[0017] Additionally, when shifting to the third gear, as the sleeve moves in the direction of the third gear shift, the first meshing part is disengaged from the fourth meshing part and released from meshing, and the second meshing part is engaged with the sixth meshing part, while the third meshing part is engaged with the seventh meshing part provided on the outer diameter of the first ring gear.

[0018] In addition, the first meshing part and the fourth meshing part may be composed of spline teeth, the second meshing part and the fifth and sixth meshing parts may be composed of spline teeth, and the third meshing part and the seventh meshing part may be composed of spline teeth.

[0019] In addition, the power transmitted to the second carrier can be transmitted to one axle shaft via the intershaft, and the power transmitted to the third ring gear can be transmitted to the other axle shaft.

[0020] In addition, the sleeve can be moved by a transfer device in any one of the 1st gear shift direction, 2nd gear shift direction, and 3rd gear shift direction.

[0021] The present invention can be easily mounted on a vehicle package due to a reduction structure consisting of a plurality of planetary gear sets.

[0022] In addition, since the present invention enables 1st, 2nd, and 3rd gear shifting, low-speed vehicle speed control and high-speed vehicle speed control are possible.

[0023] In addition, since the present invention is composed of a plurality of planetary gear sets, it does not occupy a large amount of space when mounted on a vehicle.

[0024] In addition, the present invention can control the shifting by the operation of the sleeve.

[0025] In addition, the present invention can reduce the number of parts compared to the power transmission system of existing electric vehicles, thereby enabling cost reduction, weight reduction, and simplification of the assembly process.

[0026] FIG. 1 is a drawing showing the overall configuration according to a preferred embodiment of the present invention.

[0027] FIG. 2 is a diagram showing the power flow during a first-stage shift according to a preferred embodiment of the present invention.

[0028] FIG. 3 is a diagram showing the power flow during two-stage shifting according to a preferred embodiment of the present invention.

[0029] FIG. 4 is a diagram showing the power flow during a three-stage transmission according to a preferred embodiment of the present invention.

[0030] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the present invention, such detailed description is omitted. Additionally, while preferred embodiments of the present invention will be described below, the technical concept of the present invention is not limited or restricted thereto and can be modified and implemented in various ways by those skilled in the art.

[0031] FIG. 1 is a drawing showing the overall configuration according to a preferred embodiment of the present invention, FIG. 2 is a drawing showing the power flow during a first gear shift according to a preferred embodiment of the present invention, FIG. 3 is a drawing showing the power flow during a second gear shift according to a preferred embodiment of the present invention, and FIG. 4 is a drawing showing the power flow during a third gear shift according to a preferred embodiment of the present invention.

[0032] As illustrated in FIGS. 1 to 4, the present invention may include a first planetary gear set (10), a second planetary gear set (20), a third planetary gear set (30), and a fourth planetary gear set (40) mounted inside a case (CS).

[0033] The first planetary gear set (10) and the second planetary gear set (20) may be Ravigneaux-type planetary gear sets in which two different sun gears mesh with one planetary gear.

[0034] The third planetary gear set (30) and the fourth planetary gear set (40) may be stacked planetary gear sets.

[0035] The first planetary gear set (10) may include a first sun gear (11), a first planetary gear (12) that meshes with the first sun gear (11), a first ring gear (13) that meshes with the first planetary gear (12), and a first carrier (14) connected to the first planetary gear (12).

[0036] A first sun gear (11) may have a hub (110) formed protruding from its center. An external gear (111) may be formed on the outer diameter of the hub (110). A plurality of first planetary gears (12) may be arranged along the circumference of the external gear (111).

[0037] The first ring gear (13) may be configured to surround the first planetary gear (12). The first planetary gear (12) may be located between the first sun gear (11) and the first ring gear (13).

[0038] The first planetary gear (12) can be engaged externally with the first planetary gear (12) and internally with the first ring gear (13) between the first sun gear (11) and the first ring gear (13).

[0039] The first planetary gear (12) can be connected to the first carrier (14) by a pin (P). The pin (P) can be connected to the first carrier (14) by passing through the center of the first planetary gear (12). The first planetary gear (12) can rotate around the pin (P).

[0040] The second planetary gear set (20) may include a second sun gear (21) and a second planetary gear (22) that meshes with the second sun gear (21).

[0041] The second sun gear (21) is directly connected to the motor (M) so that the power of the motor (M) can be directly transmitted. The second sun gear (21) may be provided on the motor shaft (MS). The second sun gear (21) may be configured to be integral with or detachable from the motor shaft (MS). The motor shaft (MS) may rotate when the motor (M) is driven. The second sun gear (21) may rotate together with the motor shaft (MS).

[0042] The second planetary gear (22) may be arranged in multiple numbers along the circumference of the second sun gear (21). The second planetary gear (22) may be engaged externally with the second sun gear (21) and simultaneously engaged externally with the first planetary gear (12) between the second sun gear (21) and the first planetary gear (12).

[0043] The third planetary gear set (30) may include a third sun gear (31), a plurality of third planetary gears (32) arranged along the circumference of the third sun gear (31), a second ring gear (33) configured to surround the third planetary gears (32), and a second carrier (34) connected to the third planetary gears (32).

[0044] The third sun gear (31) can be connected to the power of the first ring gear (13). The power transmitted to the first ring gear (13) can be transmitted to the third sun gear (31).

[0045] The third planetary gear (32) can be engaged externally with the third sun gear (31) and internally with the second ring gear (33) between the third sun gear (31) and the second ring gear (33).

[0046] The third planetary gear (32) can be connected to the second carrier (34) by a pin (P). The pin (P) can be connected to the second carrier (34) by passing through the center of the third planetary gear (32). The third planetary gear (32) can rotate around the pin (P).

[0047] The fourth planetary gear set (40) may include a fourth sun gear (41), a plurality of fourth planetary gears (42) arranged along the circumference of the fourth sun gear (41), a third ring gear (43) surrounding the fourth planetary gears (42), and a third carrier (44) connected to the fourth planetary gears (42).

[0048] The fourth sun gear (41) may be formed integrally with the second ring gear (33). The fourth sun gear (41) may be provided on the outer diameter portion of the second ring gear (33).

[0049] The fourth planetary gear (42) can be engaged externally with the fourth sun gear (41) and internally with the third ring gear (43) between the fourth sun gear (41) and the third ring gear (43).

[0050] The fourth planetary gear (42) can be connected to the third carrier (44) by a pin (P). The pin (P) can be connected to the third carrier (44) by passing through the center of the fourth planetary gear (42). The fourth planetary gear (42) can rotate around the pin (P). The third carrier (44) is fixed to the case (CS) and cannot rotate.

[0051] A sleeve (50) may be mounted inside the case (CS). The sleeve (50) may perform a shift of 1st gear, 2nd gear, and 3rd gear by shift operation.

[0052] The sleeve (50) may include a first engagement portion (51), a second engagement portion (52), and a third engagement portion (53). The first engagement portion (51) may be provided on the outer diameter portion of the sleeve (50). The second engagement portion (52) may be provided on one side of the inner diameter portion of the sleeve (50). The third engagement portion (53) may be provided on the other side of the inner diameter portion of the sleeve (50).

[0053] A fourth meshing portion (CS4) may be provided in the case (CS). A fifth meshing portion (145) may be provided on the outer diameter of the first carrier (14). A sixth meshing portion (116) may be provided on the outer diameter of the first sun gear (11). A seventh meshing portion (137) may be provided on the outer diameter of the first ring gear (13).

[0054] The first engagement portion (51) of the sleeve (50) can be engaged to the fourth engagement portion (CS4) of the case (CS) during 1st gear shift. The first engagement portion (51) of the sleeve (50) can be engaged to the fourth engagement portion (CS4) of the case (CS) during 2nd gear shift. The first engagement portion (51) of the sleeve (50) can be disengaged from the fourth engagement portion (CS4) of the case (CS) during 3rd gear shift.

[0055] The second meshing portion (52) of the sleeve (50) can be engaged with the fifth meshing portion (145) of the first carrier (14) during first gear shifting. The second meshing portion (52) of the sleeve (50) can be engaged with the sixth meshing portion (116) of the first sun gear (11) during second gear shifting. The second meshing portion (52) of the sleeve (50) can be engaged with the sixth meshing portion (116) of the first sun gear (11) during third gear shifting.

[0056] The third meshing portion (53) of the sleeve (50) can be engaged with the seventh meshing portion (137) of the first ring gear (13) during 3rd gear shifting.

[0057] The first meshing portion (51) of the sleeve (50) and the fourth meshing portion (CS4) of the case (CS) can be formed with a spline tooth form of an internal gear.

[0058] The second meshing portion (52) of the sleeve (50) and the fifth meshing portion (145) of the first carrier (14) can be formed with spline teeth of an internal gear.

[0059] The second meshing portion (52) of the sleeve (50) and the sixth meshing portion (116) of the first sun gear (11) can be formed with spline teeth of an internal gear.

[0060] The third meshing portion (53) of the sleeve (50) and the seventh meshing portion (137) of the first ring gear (13) can be formed with spline teeth of an internal gear.

[0061] The power transmitted to the second carrier (34) can be transmitted to one side axle shaft (not shown) via the intershaft (60). The power transmitted to the one side axle shaft (not shown) can be transmitted to the final one side drive wheel (not shown).

[0062] The power transmitted to the third ring gear (43) can be transmitted to the other axle shaft (70). The power transmitted to the other axle shaft (70) can be transmitted to the final other drive wheel (not shown).

[0063] The sleeve (50) can be moved in any one of the 1st gear, 2nd gear, and 3rd gear shift directions by a transfer device (AC) such as an actuator.

[0064] The intershaft (60) can be configured to penetrate the interior of the motor shaft (MS), which is a hollow shaft.

[0065] A support member (80), such as a bearing, can be coupled to the motor shaft (MS). The inner diameter portion of the first sun gear (11) can be rotatably coupled to the outer diameter portion of the support member (80).

[0066] The following describes the power flow during the first gear shift of the present invention.

[0067] When shifting to 1st gear, the power flow can be configured as shown by the arrow in Fig. 2.

[0068] As shown in FIG. 2, as the sleeve (50) moves in the first gear shift direction, the first engagement portion (51) of the sleeve (50) engages with the fourth engagement portion (CS4) of the case (CS), and at the same time, the second engagement portion (52) of the sleeve (50) engages with the fifth engagement portion (145) of the first carrier (14).

[0069] In this state, the power of the motor (M) can be transmitted to the second sun gear (21) via the motor shaft (MS). Since the second sun gear (21) and the second planetary gear (22) are engaged, the power transmitted to the second sun gear (21) can be transmitted to the second planetary gear (22).

[0070] At this time, the first sun gear (11) can idle because it is not affected by the sleeve (50).

[0071] Since the second planetary gear (22) and the first planetary gear (12) are engaged, the power transmitted to the second planetary gear (22) can be transmitted to the first planetary gear (12).

[0072] At this time, the first carrier (14) cannot rotate because it is in a restrained state in which the first engagement portion (51) of the sleeve (50) is engaged with the fourth engagement portion (CS4) of the case (CS) and the second engagement portion (52) of the sleeve (50) is engaged with the fifth engagement portion (145) of the first carrier (14).

[0073] Since the first planetary gear (12) and the first ring gear (13) are engaged, the power transmitted to the first planetary gear (12) can be transmitted to the first ring gear (13).

[0074] Since the power of the first ring gear (13) and the third sun gear (31) is connected, the power transmitted to the first ring gear (13) can be transmitted to the third sun gear (31).

[0075] Since the third sun gear (31) and the third planetary gear (32) are engaged, the power transmitted to the third sun gear (31) can be transmitted to the third planetary gear (32).

[0076] Since the third planetary gear (32) and the second ring gear (33) are engaged, the power transmitted to the third planetary gear (32) can be transmitted to the second ring gear (33). At the same time, since the third planetary gear (32) and the second carrier (34) are connected, the power transmitted to the third planetary gear (32) can be transmitted to one axle shaft (not shown) via the second carrier (34) and the intershaft (60).

[0077] Since the fourth sun gear (41) and the fourth planetary gear (42) are meshed together with the second ring gear (33), the power transmitted to the second ring gear (33) can be transmitted to the fourth planetary gear (42) via the fourth sun gear (41).

[0078] Since the fourth planetary gear (42) and the third ring gear (43) are engaged, the power transmitted to the fourth planetary gear (42) can be transmitted to the third ring gear (43).

[0079] At this time, the third carrier (44) cannot rotate because it is fixed to the case (CS).

[0080] The power transmitted to the third ring gear (43) can be transmitted to the other axle shaft (70).

[0081] In this way, the power transmitted to the second carrier (34) is transmitted to the final one-sided drive wheel (not shown) via the intershaft (60) and one-sided axle shaft (not shown), and at the same time, the power transmitted to the third ring gear (43) is transmitted to the final other-sided drive wheel (not shown) via the other-sided axle shaft (70), thereby enabling 1st gear driving.

[0082] The following describes the power flow during the two-stage shifting of the present invention.

[0083] When shifting to 2nd gear, the power flow can be configured as shown by the arrow in Fig. 3.

[0084] As shown in FIG. 3, as the sleeve (50) moves in the 2nd gear shift direction, the first meshing portion (51) of the sleeve (50) is engaged with the fourth meshing portion (CS4) of the case (CS), and at the same time, the second meshing portion (52) of the sleeve (50) can be engaged with the sixth meshing portion (116) of the first sun gear (11).

[0085] In this state, the power of the motor (M) can be transmitted to the second sun gear (21) via the motor shaft (MS). Since the second sun gear (21) and the second planetary gear (22) are engaged, the power transmitted to the second sun gear (21) can be transmitted to the second planetary gear (22).

[0086] Since the second planetary gear (22) and the first planetary gear (12) are engaged, the power transmitted to the second planetary gear (22) can be transmitted to the first planetary gear (12).

[0087] At this time, the first meshing portion (51) of the sleeve (50) is engaged with the fourth meshing portion (CS4) of the case (CS), and the second meshing portion (52) of the sleeve (50) is engaged with the third meshing portion (53) of the first sun gear (11), so the first sun gear (11) cannot rotate.

[0088] Since the first planetary gear (12) and the first ring gear (13) are engaged, the power transmitted to the first planetary gear (12) can be transmitted to the first ring gear (13).

[0089] Since the power of the first ring gear (13) and the third sun gear (31) is connected, the power transmitted to the first ring gear (13) can be transmitted to the third sun gear (31).

[0090] Since the third sun gear (31) and the third planetary gear (32) are engaged, the power transmitted to the third sun gear (31) can be transmitted to the third planetary gear (32).

[0091] Since the third planetary gear (32) and the second ring gear (33) are engaged, the power transmitted to the third planetary gear (32) can be transmitted to the second ring gear (33). At the same time, since the third planetary gear (32) and the second carrier (34) are connected, the power transmitted to the third planetary gear (32) can be transmitted to one axle shaft (not shown) via the second carrier (34) and the intershaft (60).

[0092] Since the fourth sun gear (41) and the fourth planetary gear (42) are meshed together with the second ring gear (33), the power transmitted to the second ring gear (33) can be transmitted to the fourth planetary gear (42) via the fourth sun gear (41).

[0093] Since the fourth planetary gear (42) and the third ring gear (43) are engaged, the power transmitted to the fourth planetary gear (42) can be transmitted to the third ring gear (43).

[0094] At this time, the third carrier (44) cannot rotate because it is fixed to the case (CS).

[0095] The power transmitted to the third ring gear (43) can be transmitted to the other axle shaft (70).

[0096] In this way, power transmitted to the second carrier (34) is transmitted to the final one-sided drive wheel (not shown) via the intershaft (60) and one-sided axle shaft (not shown), and at the same time, power transmitted to the third ring gear (43) is transmitted to the final other-sided drive wheel (not shown) via the other-sided axle shaft (70), thereby enabling two-stage driving.

[0097] The following describes the power flow during the 3-stage shifting of the present invention.

[0098] When shifting to 3rd gear, the power flow can be configured as shown by the arrow in Fig. 4.

[0099] As shown in FIG. 4, as the sleeve (50) moves in the 3rd gear shift direction, the first meshing portion (51) of the sleeve (50) is disengaged from the fourth meshing portion (CS4) of the case (CS) and simultaneously the second meshing portion (52) of the sleeve (50) is engaged with the sixth meshing portion (116) of the first sun gear (11), and the third meshing portion (53) of the sleeve (50) can be engaged with the seventh meshing portion (137) of the first ring gear (13).

[0100] In this state, the power of the motor (M) can be transmitted to the second sun gear (21) via the motor shaft (MS). Since the second sun gear (21) and the second planetary gear (22) are engaged, the power transmitted to the second sun gear (21) can be transmitted to the second planetary gear (22).

[0101] Since the second planetary gear (22) and the first planetary gear (12) are engaged, the power transmitted to the second planetary gear (22) can be transmitted to the first planetary gear (12).

[0102] Since the first planetary gear (12) and the first ring gear (13) are engaged, the power transmitted to the first planetary gear (12) can be transmitted to the first ring gear (13).

[0103] Since the first ring gear (13) and the third sun gear (31) are connected by power, the power transmitted to the first ring gear (13) can be transmitted to the third sun gear (31).

[0104] Since the third sun gear (31) and the third planetary gear (32) are engaged, the power transmitted to the third sun gear (31) can be transmitted to the third planetary gear (32).

[0105] Since the third planetary gear (32) and the second ring gear (33) are engaged, the power transmitted to the third planetary gear (32) can be transmitted to the second ring gear (33). At the same time, since the third planetary gear (32) and the second carrier (34) are connected, the power transmitted to the third planetary gear (32) can be transmitted to one axle shaft (not shown) via the second carrier (34) and the intershaft (60).

[0106] Since the fourth sun gear (41) and the fourth planetary gear (42) are meshed together with the second ring gear (33), the power transmitted to the second ring gear (33) can be transmitted to the fourth planetary gear (42) via the fourth sun gear (41).

[0107] Since the fourth planetary gear (42) and the third ring gear (43) are engaged, the power transmitted to the fourth planetary gear (42) can be transmitted to the third ring gear (43).

[0108] At this time, the third carrier (44) cannot rotate because it is fixed to the case (CS).

[0109] The power transmitted to the third ring gear (43) can be transmitted to the other axle shaft (70).

[0110] In this way, power transmitted to the second carrier (34) is transmitted to the final one-sided drive wheel (not shown) via the intershaft (60) and one-sided axle shaft (not shown), and at the same time, power transmitted to the third ring gear (43) is transmitted to the final other-sided drive wheel (not shown) via the other-sided axle shaft (70), thereby enabling three-stage driving.

[0111] As described above, the present invention facilitates easy installation in a vehicle package due to its reduction structure composed of multiple planetary gear sets. Furthermore, since the present invention enables 1st, 2nd, and 3rd gear shifting, it allows for low-speed and high-speed vehicle speed control. Additionally, as the present invention is composed of multiple planetary gear sets, it does not occupy a large amount of space when installed in a vehicle. Moreover, the present invention can control gear shifting by the operation of a sleeve. Furthermore, the present invention can reduce the number of parts compared to the power transmission system of existing electric vehicles, thereby enabling cost reduction, weight reduction, and simplification of the assembly process.

[0112] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications, changes, and substitutions within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by such embodiments and accompanying drawings. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

1. A power transmission device for an electric vehicle characterized in that a first planetary gear set, a second planetary gear set, a third planetary gear set, and a fourth planetary gear set are mounted inside a case so as to be connected to each other, and a sleeve moves in the first gear shift direction to restrain the first carrier of the first planetary gear set to achieve a first gear shift, or a sleeve moves in the second gear shift direction to restrain the first sun gear of the first planetary gear set to achieve a second gear shift, or a sleeve moves in the third gear shift direction to mesh simultaneously with the first sun gear and the first ring gear of the first planetary gear set to achieve a third gear shift.

2. In Paragraph 1, The above-mentioned first planetary gear set is, The first sun gear is provided with a hub, and an external gear is provided on the outer diameter of the hub, and a first planetary gear is arranged along the circumference of the external gear, and a first ring gear is provided to surround the first planetary gear, and the first planetary gear is engaged externally with the first planetary gear between the first sun gear and the first ring gear, and at the same time engaged internally with the first ring gear. The above second planetary gear set is, It includes a second sun gear provided on a motor shaft and a second planetary gear arranged along the circumference of the second sun gear, wherein the second planetary gear is engaged externally with the second sun gear between the second sun gear and the first planetary gear, and simultaneously engaged externally with the first planetary gear. The above third planetary gear set is, It includes a third sun gear connected to the first ring gear, a third planetary gear arranged along the circumference of the third sun gear, and a second ring gear surrounding the third planetary gear, wherein the third planetary gear is engaged externally with the third sun gear and internally with the second ring gear between the third sun gear and the second ring gear. The above-mentioned fourth planetary gear set is, A power transmission device for an electric vehicle comprising a fourth sun gear provided on the outer diameter portion of the second ring gear, a fourth planetary gear arranged along the circumference of the fourth sun gear, and a third ring gear surrounding the fourth planetary gear, wherein the fourth planetary gear is engaged externally with the fourth sun gear and simultaneously engaged internally with the third ring gear between the fourth sun gear and the third ring gear.

3. In Paragraph 2, A power transmission device for an electric vehicle characterized in that the third carrier is fixed to the case, the first planetary gear is rotatably connected to the first carrier, the first carrier is positioned between the first sun gear and the first ring gear, the third planetary gear is rotatably connected to the second carrier, the second carrier is connected to the intershaft, and the fourth planetary gear is rotatably connected to the third carrier.

4. In Paragraph 3, A sleeve is mounted inside the above case, and one of the 1st, 2nd, and 3rd gear shifts is achieved by the operation of the sleeve, and The above sleeve is, A first meshing portion provided on the outer diameter; A second meshing portion provided on one side of the inner diameter portion; and A third meshing part provided on the other side of the inner diameter part; A power transmission system for an electric vehicle including 5. In Paragraph 4, When shifting to 1st gear, A power transmission device for an electric vehicle characterized in that, as the sleeve moves in the first gear shift direction, the first meshing portion engages with the fourth meshing portion provided in the case, and the second meshing portion engages with the fifth meshing portion provided in the outer diameter portion of the first carrier.

6. In Paragraph 5, When shifting to 2nd gear, A power transmission device for an electric vehicle characterized in that, as the sleeve moves in the second gear shift direction, the first meshing part engages with the fourth meshing part, and the second meshing part engages with the sixth meshing part provided on the outer diameter of the first sun gear.

7. In Paragraph 6, When shifting to 3rd gear, A power transmission device for an electric vehicle characterized in that as the sleeve moves in the 3rd gear shift direction, the first meshing part separates from the fourth meshing part and is released from meshing, and the second meshing part engages with the sixth meshing part while the third meshing part engages with the seventh meshing part provided on the outer diameter of the first ring gear.

8. In Paragraph 7, A power transmission device for an electric vehicle characterized in that the first meshing part and the fourth meshing part are composed of spline teeth, the second meshing part and the fifth and sixth meshing parts are composed of spline teeth, and the third meshing part and the seventh meshing part are composed of spline teeth.

9. In Paragraph 3, A power transmission device for an electric vehicle characterized in that the power transmitted to the second carrier is transmitted to one axle shaft via an intershaft, and the power transmitted to the third ring gear is transmitted to the other axle shaft.

10. In Paragraph 1, The above sleeve is, A power transmission device for an electric vehicle characterized by being movable in any one of the 1st gear shift direction, 2nd gear shift direction, and 3rd gear shift direction by means of a transfer device.

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