Power train device of electric vehicle

Abstract

The present invention has been made in an effort to provide a power train system of an electric vehicle having advantages of being easily mounted on a vehicle package by a speed reduction structure including a plurality of planetary gear sets.SOLUTION: According to an aspect of the present invention, there is provided a power transmission device of an electric vehicle including a first planetary gear set including a first sun gear, a first ring gear, a first planetary gear, and a first carrier, a second planetary gear set including a second sun gear, a second ring gear, a second planetary gear, and a second carrier, a third planetary gear set including a third ring gear, a third planetary gear, and a third carrier, and a sleeve having a first engagement part provided on an inner diameter portion thereof and always engaged with a third engagement part provided on the first ring gear.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Due to exhaust gas regulations and the reduction of fossil fuel energy consumption, there is an increasing demand for electric vehicles (fuel cell vehicles) for everyday use such as freight transport trucks and buses.

[0003] In an electric vehicle, the power of a drive motor can be transmitted to drive wheels through a reducer and an axle.

[0004] Conventionally, the power electronics (PE) system of an electric vehicle can be divided into two types: a central motor type that receives power from a drive motor and transmits it to the axle through a reduction gear, and an electric axle (E-Axle) type that includes a drive motor, reduction gear, and axle differential.

[0005] In conventional electric vehicles, the installation space for the battery pack is larger than that of internal combustion engine vehicles, so the power electronics (PE) system, which combines the motor, inverter, and reducer, needs to be more compact.

[0006] However, in the powertrain layout characteristics of conventional electric vehicles (E-Axles), it was difficult for a single-stage reducer to meet the performance requirements of electric vehicles. Furthermore, applying a high-performance drive motor not only took up a lot of installation space, but also increased costs. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Republic of Korea Patent Publication No. 10-2007-0076773 (Published on July 25, 2007) Summary of the Invention [Problem to be solved by the invention]

[0008] In order to solve the above-mentioned problems, the present invention aims to provide a power transmission device for an electric vehicle that can be easily mounted on a vehicle package by using a reduction structure composed of multiple planetary gear sets. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the present invention provides a first planetary gear set including a first sun gear coupled to an input shaft coupled to a drive motor, a first ring gear configured to surround the first sun gear, first planetary gears meshed with the first sun gear and the first ring gear between the first sun gear and the first ring gear, and a first carrier rotatably supporting the first planetary gears; a second sun gear power-connected to the first carrier, a second ring gear configured to surround the second sun gear, and a first carrier rotatably supporting the first planetary gears; a second planetary gear set including a second planetary gear meshed with a second ring gear and a second carrier rotatably supporting the second planetary gear; a third ring gear configured to surround the second ring gear, a third planetary gear meshed with the second ring gear and the third ring gear between the second ring gear and the third ring gear, and a third carrier rotatably supporting the third planetary gear; and a sleeve having a first meshing portion on an inner diameter portion thereof, the first meshing portion being constantly meshed with a third meshing portion provided on the first ring gear.

[0010] Also, the first planetary gear set, the second planetary gear set, and the third planetary gear set may be mounted inside a case.

[0011] Also, a second meshing portion may be provided on the outer diameter portion of the sleeve, and a fifth meshing portion may be provided on the outer diameter portion of the first carrier (first embodiment).

[0012] Furthermore, during one-speed shifting, as the sleeve moves in the one-speed shifting direction, the first meshing portion can remain meshed with the third meshing portion, while the second meshing portion can mesh with the fourth meshing portion inside the case (first embodiment).

[0013] Furthermore, during two-speed shifting, as the sleeve moves in the two-speed shifting direction, the first meshing portion simultaneously meshes with the fifth meshing portion while maintaining a meshed state with the third meshing portion, and the second meshing portion can disengage at the fourth meshing portion (first embodiment).

[0014] In addition, the first meshing portion, the third meshing portion, and the fifth meshing portion may be configured with spline teeth of an inscribed gear, and the second meshing portion and the fourth meshing portion may be configured with spline teeth of an inscribed gear (first embodiment).

[0015] In addition, a second meshing portion may be provided on one surface of the sleeve, a fifth meshing portion may be provided on one surface of the first carrier, and a sixth meshing portion may be provided on the other surface of the sleeve opposite the fifth meshing portion (second embodiment).

[0016] Furthermore, during one-speed shifting, as the sleeve moves in the one-speed shifting direction, the first meshing portion can remain meshed with the third meshing portion, while the second meshing portion can mesh with the fourth meshing portion inside the case (second embodiment).

[0017] Furthermore, during two-speed shifting, as the sleeve moves in the two-speed shifting direction, the first meshing portion maintains a meshed state with the third meshing portion, the second meshing portion disengages from the fourth meshing portion, and at the same time, the sixth meshing portion can mesh with the fifth meshing portion (second embodiment).

[0018] In addition, the first meshing portion and the third meshing portion may be configured with spline teeth of an internal gear, the second meshing portion and the fourth meshing portion may be configured with radial dog-type teeth facing each other, and the fifth meshing portion and the sixth meshing portion may be configured with radial dog-type teeth facing each other (second embodiment).

[0019] Also, a fifth meshing portion may be provided on the outer diameter portion of the first carrier, and a fourth meshing portion may be provided inside the case (third embodiment).

[0020] Furthermore, during one-stage shifting, as the sleeve moves in the one-stage shifting direction, the first meshing portion can be simultaneously meshed with the fourth meshing portion while maintaining a meshed state with the third meshing portion (third embodiment).

[0021] Furthermore, during two-speed shifting, as the sleeve moves in the two-speed shifting direction, the first meshing portion can simultaneously mesh with the fifth meshing portion while maintaining a meshed state with the third meshing portion (third embodiment).

[0022] The first meshing portion, the fourth meshing portion, and the fifth meshing portion may be configured with spline teeth of an internal gear (third embodiment).

[0023] The number of the second planetary gears may be greater than the number of the third planetary gears.

[0024] Six of the second planetary gears may be arranged along the outer diameter portion of the second sun gear, and five of the third planetary gears may be arranged along the outer diameter portion of the second ring gear.

[0025] Also, the third carrier may be fixed to the case.

[0026] In addition, the power transmitted to the second carrier may be transmitted to one axle shaft via an intermediate shaft, and the power transmitted to the third ring gear may be transmitted to the other axle shaft.

[0027] In addition, the sleeve can be moved in a one-stage speed change direction or a two-stage speed change direction by a control unit.

[0028] The present invention can facilitate vehicle package installation by using a reduction gear structure composed of multiple planetary gear sets.

[0029] Furthermore, the present invention allows for one-stage and two-stage speed change, making it possible to control low-speed vehicle speeds and high-speed vehicle speeds.

[0030] Furthermore, the present invention does not take up much space when installed in a vehicle because it is configured with multiple planetary gear sets.

[0031] Furthermore, the present invention allows for speed change control by operating the sleeve.

[0032] Furthermore, the present invention can reduce the number of parts compared to conventional electric vehicle power transmission devices, thereby reducing costs, weight, and simplifying the assembly process. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a diagram illustrating operation at one stage according to a preferred embodiment of the present invention. [Figure 2] 1 is a diagram illustrating a two-stage operation according to a preferred embodiment of the present invention. [Figure 3] 4A to 4C are diagrams showing the operation of a sleeve at 1st stage, Nth stage, and 2nd stage according to the first embodiment of the present invention. [Figure 4] 1 is a diagram showing a first planetary gear set according to a preferred embodiment of the present invention. [Figure 5] 1 is a diagram showing a second planetary gear set and a third planetary gear set according to a preferred embodiment of the present invention. [Figure 6] 10 is a diagram showing the operation of a sleeve at 1st stage, Nth stage, and 2nd stage according to a second embodiment of the present invention. [Figure 7]10 is a diagram showing the operation of a sleeve at 1st stage, Nth stage, and 2nd stage according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, when assigning reference numerals to components in each drawing, it should be noted that the same reference numerals are assigned to identical components when they appear in other drawings as much as possible. Furthermore, when describing the present invention, if a detailed description of related well-known structures or functions is deemed to obscure the gist of the present invention, such a detailed description will be omitted. Furthermore, although a preferred embodiment of the present invention will be described below, the technical concept of the present invention is not limited thereto, and it goes without saying that it can be modified and implemented in various ways by those skilled in the art.

[0035] FIG. 1 is a diagram showing operation in one stage according to a preferred embodiment of the present invention, FIG. 2 is a diagram showing operation in two stages according to a preferred embodiment of the present invention, FIG. 3 is a diagram showing operation of the sleeve in one stage, Nth stage, and second stage according to a first embodiment of the present invention, FIG. 4 is a diagram showing a first planetary gear set according to a preferred embodiment of the present invention, and FIG. 5 is a diagram showing a second planetary gear set and a third planetary gear set according to a preferred embodiment of the present invention.

[0036] As shown in Figures 1 to 5, the present invention includes a first planetary gear set PS1 power-connected to a drive motor MG, a second planetary gear set PS2 power-connected to the first planetary gear set PS1, a third planetary gear set PS3 power-connected to the second planetary gear set PS2, and a sleeve SL that moves axially to perform one-stage or two-stage shifting.

[0037] The drive motor MG may be composed of a stator ST and a rotor RT, and may be coupled to an inverter INV.

[0038] The first planetary gear set PS1, the second planetary gear set PS2, the third planetary gear set PS3, and the sleeve SL may be mounted inside the case CS.

[0039] The first planetary gear set PS1 may include a first sun gear S1, a first planetary gear P1, a first carrier C1, and a first ring gear R1.

[0040] The first sun gear S1 may be mounted on an outer diameter portion of the input shaft IP connected to the drive motor MG, and may be located inside the first ring gear R1.

[0041] The first ring gear R1 can be configured to surround the first sun gear S1.

[0042] The first planetary gear P1 may be simultaneously meshed with the first sun gear S1 and the first ring gear R1 between the first sun gear S1 and the first ring gear R1. A plurality of first planetary gears P1 may be arranged along the outer diameter portion of the first sun gear S1. For example, five first planetary gears P1 may be arranged along the outer diameter portion of the first sun gear S1.

[0043] The first carrier C1 can be configured integrally with the first planetary gear P1. The first planetary gear P1 can rotate while being supported by the first carrier C1.

[0044] The second planetary gear set PS2 may include a second sun gear S2, a second planetary gear P2, a second carrier C2, and a second ring gear R2.

[0045] The second sun gear S2 may be power-connected to the first carrier C1 and may be located inside the second ring gear R2.

[0046] The second ring gear R2 may be configured to surround the second sun gear S2 and may perform the ring gear function of the second planetary gear set PS2 and the sun gear function of the third planetary gear set PS3.

[0047] The second planetary gear P2 may be simultaneously meshed with the second sun gear S2 and the second ring gear R2 between the second sun gear S2 and the second ring gear R2. A plurality of second planetary gears P2 may be arranged along the outer diameter portion of the second sun gear S2. For example, six second planetary gears P2 may be arranged along the outer diameter portion of the second sun gear S2.

[0048] The second carrier C2 may be integrally formed with the second planetary gear P2. The second planetary gear P2 may rotate while being supported by the second carrier C2. One side of the second carrier C2 may be connected to an intermediate shaft IS. The intermediate shaft IS may be connected to one side of an axle shaft (not shown).

[0049] The third planetary gear set PS3 may include a third planetary gear P3, a third carrier C3, and a third ring gear R3.

[0050] The third ring gear R3 may be configured to surround the second ring gear R2. The third planetary gear P3 may be simultaneously meshed with the second ring gear R2 and the third ring gear R3 between the second ring gear R2 and the third ring gear R3. A plurality of third planetary gears P3 may be arranged along the outer diameter of the second ring gear R2. For example, five third planetary gears P3 may be arranged along the outer diameter of the second ring gear R2.

[0051] The third carrier C3 may be integral with the third planetary gear P3. The third planetary gear P3 may rotate while being supported by the third carrier C3. The third carrier C3 may be fixed to the case CS.

[0052] One side of the third ring gear R3 may be connected to the other axle shaft AS. The intermediate shaft IS and the other axle shaft AS may be configured to face each other on both sides. For example, the intermediate shaft IS may be configured to pass through the input shaft IP.

[0053] The sleeve SL, which performs the speed change operation, may include a first meshing portion IR1 and a second meshing portion IR2. The first meshing portion IR1 may be provided on an inner diameter portion of the sleeve SL. The second meshing portion IR2 may be provided on an outer diameter portion of the sleeve SL. The first meshing portion IR1 and the second meshing portion IR2 may be formed by splines. The first meshing portion IR1 may be constantly meshed with a third meshing portion IR3 provided on the outer diameter portion of the first ring gear R1.

[0054] During one-speed shifting, as the sleeve SL moves in the one-speed shifting direction, the second meshing portion IR2 can mesh with the fourth meshing portion IR4 provided inside the case CS. Even when the sleeve SL moves in the one-speed shifting direction, the meshed state between the first meshing portion IR1 and the third meshing portion IR3 can be maintained as is (see FIG. 3(a)).

[0055] During N (Natural) gear shifting, as the sleeve SL moves in the N gear shifting direction, the second meshing portion IR2 can disengage from the third meshing portion IR3. Even when the sleeve SL moves in the N gear shifting direction, the meshed state between the first meshing portion IR1 and the third meshing portion IR3 can be maintained as is (see FIG. 3(b)).

[0056] During two-speed shifting, as the sleeve SL moves in the two-speed shifting direction, the first meshing portion IR1 can simultaneously mesh with the third meshing portion IR3 and the fifth meshing portion IR5 provided on the outer diameter portion of the first carrier C1. When the sleeve SL moves in the two-speed shifting direction, the second meshing portion IR2 can be disengaged from the fourth meshing portion IR4 (see FIG. 3(c)).

[0057] The first ring gear R1 is fixed so that it cannot rotate during first-speed shifting, and is released during second-speed shifting so that it can rotate integrally with the first carrier C1. The first carrier C1 is power-coupled to the second sun gear S2, so that the first carrier C1 and the second sun gear S2 can always rotate integrally.

[0058] As shown in Fig. 3, the first meshing portion IR, the third meshing portion IR3, and the fifth meshing portion IR5 may be configured with a spline tooth shape of an internal gear, and the second meshing portion IR2 and the fourth meshing portion IR4 may be configured with a spline tooth shape of an internal gear.

[0059] 1 to 3, the operation of the sleeve SL can be controlled by a control unit. The sleeve SL can move in a one-speed shift direction or a two-speed shift direction by the operation of the control unit. For example, the control unit may be an actuator.

[0060] FIG. 6 is a diagram showing the operation of the sleeve at the first stage, Nth stage, and second stage according to the second embodiment of the present invention.

[0061] As shown in FIG. 6, the second embodiment of the present invention may be configured in the same manner as the first embodiment, except for the meshing portion.

[0062] A second meshing portion IR2 may be provided on one surface of the sleeve SL. A fifth meshing portion IR5 may be provided on one surface of the first carrier C1. A sixth meshing portion IR6 may be provided on the other surface of the sleeve SL opposite the fifth meshing portion IR5.

[0063] The first and third meshing portions IR and IR3 may be configured with spline teeth of an internal gear. The teeth of the first and third meshing portions IR and IR3 may be formed at a predetermined interval and may be configured as a square or trapezoid.

[0064] The second and fourth meshing parts IR2 and IR4 may have radial dog-type teeth facing each other. The teeth of the second and fourth meshing parts IR2 and IR4 may be formed at a predetermined interval and may be rectangular or trapezoidal.

[0065] The fifth and sixth meshing parts IR5 and IR6 may have radial dog-type teeth facing each other. The teeth of the fifth and sixth meshing parts IR5 and IR6 may be formed at a predetermined interval and may be rectangular or trapezoidal.

[0066] FIG. 7 is a diagram showing the operation of the sleeve at the first stage, Nth stage, and second stage according to the third embodiment of the present invention.

[0067] As shown in FIG. 7, the third embodiment of the present invention may have the same configuration as the first embodiment, except for the meshing portion.

[0068] A fifth engagement portion IR5 may be provided on the outer periphery of the first carrier C1, and a fourth engagement portion IR4 may be provided inside the case CS.

[0069] The first, fourth, and fifth meshing portions IR4, IR5 may be configured with spline teeth of an internal gear. The teeth of the first, fourth, and fifth meshing portions IR4, IR5 may be formed at predetermined intervals and may be configured as a square or trapezoid.

[0070] The fourth engagement portion IR4 may be configured integrally with the case CS or separably therefrom.

[0071] Next, the operation of the first embodiment of the present invention during one-speed shifting will be described.

[0072] As shown in Figs. 1, 3(a), 4 and 5, when shifting by one speed, the sleeve SL can be moved in the direction of shifting by one speed by operation of the control unit.

[0073] As the sleeve SL moves in the direction of one gear shift, the first meshing portion IR1 can be meshed with the third meshing portion IR3 of the first ring gear R1, while the second meshing portion IR2 can be meshed with the fourth meshing portion IR4 of the case CS.

[0074] The first meshing portion IR1 of the sleeve SL meshes with the third meshing portion IR3 of the first ring gear R1, and the second meshing portion IR2 of the sleeve SL meshes with the fourth meshing portion IR4 of the case CS, thereby fixing the first ring gear R1.

[0075] With the first ring gear R1 in a fixed state, the power of the drive motor MG can be transmitted to the first sun gear S1 via the input shaft IP.

[0076] The power transmitted to the first sun gear S1 can be transmitted to the first carrier C1 via the first sun gear S1 and the first planetary gear P1.

[0077] Since the first carrier C1 and the second sun gear S2 are connected, the power transmitted to the first carrier C1 can be transmitted to the second carrier C2 and the second ring gear R2 via the second sun gear S2 and the second planetary gear P2.

[0078] The power transmitted to the second carrier C2 may be transmitted to the intermediate shaft IS. The power transmitted to the intermediate shaft IS may be transmitted to one driving wheel (not shown) via one axle shaft (not shown).

[0079] The second ring gear R2 functions as the ring gear of the second planetary gear set PS2 and the sun gear of the third planetary gear set PS3. Power transmitted to the second ring gear R2 can be transmitted to the third ring gear R3 via the third planetary gear P3. The third carrier C3 is fixed to the case CS and cannot rotate.

[0080] The power transmitted to the third ring gear R3 can be transmitted to the other driving wheel (not shown) via the other axle shaft AS.

[0081] Next, the operation of the first embodiment of the present invention during two-speed shifting will be described.

[0082] As shown in FIGS. 2, 3(c), 4, and 5, during two-speed shifting, the sleeve SL can be moved in the two-speed shifting direction by the operation of the control unit.

[0083] As the sleeve SL moves in the two-speed shift direction, the first meshing portion IR1 can be meshed with the third meshing portion IR3 of the first ring gear R1 and simultaneously meshed with the fifth meshing portion IR5 of the first carrier C1. At the same time, the second meshing portion IR2 can be disengaged from the fourth meshing portion IR4.

[0084] When the second meshing portion IR2 disengages from the fourth meshing portion IR4, the first ring gear R1 can rotate integrally with the first carrier C1.

[0085] With the first ring gear R1 in the unlocked state, the power of the drive motor MG can be transmitted to the first sun gear S1 via the input shaft IP.

[0086] The power transmitted to the first sun gear S1 can be transmitted to the first carrier C1 via the first sun gear S1 and the first planetary gear P1.

[0087] Since the first carrier C1 and the second sun gear S2 are connected, the power transmitted to the first carrier C1 can be transmitted to the second carrier C2 and the second ring gear R2 via the second sun gear S2 and the second planetary gear P2.

[0088] The power transmitted to the second carrier C2 may be transmitted to the intermediate shaft IS. The power transmitted to the intermediate shaft IS may be transmitted to one driving wheel (not shown) via one axle shaft (not shown).

[0089] The second ring gear R2 functions as the ring gear of the second planetary gear set PS2 and the sun gear of the third planetary gear set PS3. Power transmitted to the second ring gear R2 can be transmitted to the third ring gear R3 via the third planetary gear P3. The third carrier C3 is fixed to the case CS and cannot rotate.

[0090] The power transmitted to the third ring gear R3 can be transmitted to the other drive wheel (not shown) via the other axle shaft AS.

[0091] Next, the operation of the second embodiment of the present invention during one-speed shifting will be described.

[0092] As shown in (a) of Figure 6, during one-speed shifting, as the sleeve SL moves in the one-speed shifting direction, the first meshing portion IR1 remains meshed with the third meshing portion IR3, while the second meshing portion IR2 can mesh with the fourth meshing portion IR4 provided inside the case CS.

[0093] Next, the operation of the second embodiment of the present invention during two-speed shifting will be described.

[0094] As shown in (b) and (c) of Figure 6, during two-speed shifting, as the sleeve SL moves in the two-speed shifting direction, the first meshing portion IR1 remains meshed with the third meshing portion IR3, the second meshing portion IR2 disengages from the fourth meshing portion IR4, and at the same time, the sixth meshing portion IR6 can mesh with the fifth meshing portion IR5.

[0095] Meanwhile, the operation and power flow of the second embodiment of the present invention may be the same as that of the first embodiment.

[0096] Next, the operation of the third embodiment of the present invention during one-speed shifting will be described.

[0097] As shown in (a) of Figure 7, during one-stage shifting, as the sleeve SL moves in the one-stage shifting direction, the first meshing portion IR1 can simultaneously mesh with the fourth meshing portion IR4 while maintaining a meshed state with the third meshing portion IR3.

[0098] Next, the operation of the third embodiment of the present invention during two-speed shifting will be described.

[0099] As shown in (b) and (c) of Figure 7, as the sleeve SL moves in the two-speed shift direction, the first meshing portion IR1 can simultaneously mesh with the fifth meshing portion IR5 while maintaining a meshed state with the third meshing portion IR3.

[0100] Meanwhile, the operation and power flow of the third embodiment of the present invention may be the same as that of the first embodiment.

[0101] As described above, the present invention facilitates installation in a vehicle package thanks to its reduction gear structure comprised of multiple planetary gear sets. Furthermore, the present invention allows for one- and two-speed shifting, enabling both low-speed and high-speed vehicle speed control. Furthermore, the present invention, being comprised of multiple planetary gear sets, does not occupy much space when installed in a vehicle. Furthermore, the present invention allows for speed control through the operation of a sleeve. Furthermore, the present invention reduces the number of parts compared to conventional electric vehicle power transmission devices, thereby reducing costs, weight, and simplifying the assembly process. Furthermore, the present invention is modularly comprised of a first planetary gear set, a second planetary gear set, and a third planetary gear set, and is applicable to both central motor and electric axle types.

[0102] The above description merely exemplifies the technical concept of the present invention, and those skilled in the art can make various modifications, changes, and substitutions without departing from the essential characteristics of the present invention. Therefore, the embodiments and accompanying drawings disclosed in the present invention are for illustrative purposes only, and are not intended to limit the technical concept of the present invention. The scope of the technical concept of the present invention should be interpreted by the claims, and all technical concepts within the scope equivalent thereto should be interpreted as being within the scope of the present invention. [Explanation of symbols]

[0103] PS1: First planetary gear set C1: First carrier P1: First planetary gear R1: First ring gear S1: First sun gear PS2: Second planetary gear set C2: Second Carrier P2: Second planetary gear R2: Second ring gear S2: Second sun gear PS3 3rd Planetary Gear Set C3: Third Carrier P3: Third planetary gear R3: Third ring gear SL Sleeve IR1...1st meshing part IR2...Second meshing part IR3: Third meshing part IR4: Fourth meshing part IR5...5th meshing part IR6...6th meshing part CS ···Case IS Intermediate shaft AS: Other axle shaft MG Drive motor ST: Stator RT Rotor IP ··· Input shaft INV ···Inverter Control

Claims

1. a first planetary gear set including a first sun gear coupled to an input shaft coupled to a drive motor, a first ring gear configured to surround the first sun gear, a first planetary gear meshed with the first sun gear and the first ring gear between the first sun gear and the first ring gear, and a first carrier rotatably supporting the first planetary gear; a second planetary gear set including a second sun gear power-connected to the first carrier, a second ring gear configured to surround the second sun gear, a second planetary gear meshed with the second sun gear and the second ring gear between the second sun gear and the second ring gear, and a second carrier rotatably supporting the second planetary gear; a third planetary gear set including a third ring gear configured to surround the second ring gear, a third planetary gear meshed with the second ring gear and the third ring gear between the second ring gear and the third ring gear, and a third carrier rotatably supporting the third planetary gear; and a sleeve having an inner diameter portion provided with a first meshing portion, the first meshing portion being constantly meshed with a third meshing portion provided on the first ring gear; 1. A power transmission device for an electric vehicle, comprising:

2. 2. The power transmission device for an electric vehicle according to claim 1, wherein the first planetary gear set, the second planetary gear set, and the third planetary gear set are mounted inside a case.

3. 3. The power transmission device for an electric vehicle according to claim 2, wherein a second meshing portion is provided on an outer diameter portion of the sleeve, and a fifth meshing portion is provided on an outer diameter portion of the first carrier.

4. When shifting to one gear, 4. The power transmission device for an electric vehicle according to claim 3, wherein as the sleeve moves in the direction of one gear shift, the first meshing portion maintains a meshed state with the third meshing portion, while the second meshing portion meshes with a fourth meshing portion inside the case.

5. When shifting to two speeds, 5. The power transmission device for an electric vehicle according to claim 4, wherein as the sleeve moves in the two-speed shift direction, the first meshing portion simultaneously meshes with the fifth meshing portion while maintaining a meshed state with the third meshing portion, and the second meshing portion disengages from the fourth meshing portion.

6. the first meshing portion, the third meshing portion, and the fifth meshing portion are configured with spline teeth of an internal gear, 5. The power transmission device for an electric vehicle according to claim 4, wherein the second meshing portion and the fourth meshing portion are configured with spline teeth of an internal gear.

7. 3. The power transmission device for an electric vehicle according to claim 2, wherein a second meshing portion is provided on one surface of the sleeve, a fifth meshing portion is provided on one surface of the first carrier, and a sixth meshing portion is provided on another surface of the sleeve opposite to the fifth meshing portion.

8. When shifting to one gear, 8. The power transmission device for an electric vehicle according to claim 7, wherein as the sleeve moves in the direction of one gear shift, the first meshing portion maintains a meshed state with the third meshing portion, while the second meshing portion meshes with a fourth meshing portion inside the case.

9. When shifting to two speeds, 9. The power transmission device for an electric vehicle according to claim 8, wherein, as the sleeve moves in the two-speed shift direction, the first meshing portion maintains a meshed state with the third meshing portion, the second meshing portion disengages from the fourth meshing portion, and the sixth meshing portion meshes with the fifth meshing portion.

10. the first meshing portion and the third meshing portion are configured with spline teeth of an internal gear, 9. The power transmission device for an electric vehicle according to claim 8, wherein the second meshing portion and the fourth meshing portion are configured with radial dog-type teeth facing each other, and the fifth meshing portion and the sixth meshing portion are configured with radial dog-type teeth facing each other.

11. 3. The power transmission device for an electric vehicle according to claim 2, wherein a fifth meshing portion is provided on an outer diameter portion of the first carrier, and a fourth meshing portion is provided inside the case.

12. When shifting to one gear, 12. The power transmission device for an electric vehicle according to claim 11, wherein as the sleeve moves in the direction of one gear shift, the first meshing portion simultaneously meshes with the fourth meshing portion while maintaining a meshed state with the third meshing portion.

13. When shifting to two speeds, 13. The power transmission device for an electric vehicle according to claim 12, wherein as the sleeve moves in the two-speed shift direction, the first meshing portion simultaneously meshes with the fifth meshing portion while maintaining a meshed state with the third meshing portion.

14. 13. The power transmission device for an electric vehicle according to claim 12, wherein the first meshing portion, the fourth meshing portion, and the fifth meshing portion are configured with spline teeth of an internal gear.

15. The number of the second planetary gears is 2. The power transmission device for an electric vehicle according to claim 1, wherein the number of third planetary gears exceeds the number of third planetary gears.

16. 2. The power transmission device for an electric vehicle according to claim 1, wherein six second planetary gears are arranged along an outer diameter portion of the second sun gear, and five third planetary gears are arranged along an outer diameter portion of the second ring gear.

17. The third carrier is 3. The power transmission device for an electric vehicle according to claim 2, wherein the power transmission device is fixed to the case.

18. 2. The power transmission device for an electric vehicle according to claim 1, wherein the power transmitted to the second carrier is transmitted to one axle shaft via an intermediate shaft, and the power transmitted to the third ring gear is transmitted to the other axle shaft.

19. The sleeve is 2. The power transmission device for an electric vehicle according to claim 1, wherein the power transmission device can be moved in a one-stage shift direction or a two-stage shift direction by the control unit.

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