Powertrains for electric vehicles

Abstract

The present invention relates to a power transmission system for an electric vehicle, which may include: an input shaft, to which a motor is fixedly connected; a driving gear, which is rotatably mounted on the input shaft; an output shaft, which is arranged parallel to the input shaft; a driven gear, which is fixed to the output shaft and meshes with the driving gear; a planetary gear set, which includes a first rotating element, a second rotating element and a third rotating element, wherein the first rotating element is fixedly connected to the input shaft, the second rotating element is fixedly connected to the driving gear, and the rotation of the third rotating element is constrained; a friction clutch, which is configured to selectively connect the input shaft to the driving gear; and a constraint device, which is arranged on the third rotating element to achieve two states, so that the unidirectional rotation of the third rotating element of the planetary gear set is constrained or the bidirectional rotation of the third rotating element of the planetary gear set is constrained.

Description

Technical Field

[0001] The present invention relates to a powertrain for an electric vehicle, and more particularly, to a powertrain structure in which power of a motor can be transmitted to driving wheels after gear shifting. Background Art

[0002] In an electric vehicle, rotational force generated from an electric motor (hereinafter, referred to as a "motor") is transmitted to drive wheels to drive the vehicle.

[0003] Related technologies primarily utilize a power transmission structure in which the power generated by a motor is transferred to the drive wheels after being decelerated by a simple speed reducer. In recent years, efforts have been made to more efficiently transfer power from the motor to the drive wheels, thereby extending the vehicle's mileage and improving drivability.

[0004] What is referred to as related art is provided only to help understanding the background of the present invention and may not be considered to be equivalent to the prior art known to one of ordinary skill in the art.

[0005] The information included in this Background section of the present invention is only intended to enhance understanding of the general background of the invention and should not be taken as an acknowledgment or any form of suggestion that this information constitutes the prior art already known to a person of ordinary skill in the art. Summary of the Invention

[0006] Various aspects of the present invention are directed to a powertrain for an electric vehicle configured to provide two gear ratios while having a relatively simple configuration, thereby reducing the size of the motor utilized and the weight of the vehicle, changing the operating point of the motor, and entering a neutral state in which the motor is disconnected from the drive wheels, thereby improving the energy efficiency of the vehicle.

[0007] According to various exemplary embodiments of the present invention, a power transmission system for an electric vehicle includes: an input shaft, a driving gear, an output shaft, a driven gear, a planetary gear set, a friction clutch and a constraint device, the motor is fixedly connected to the input shaft; the driving gear is rotatably mounted on the input shaft; the output shaft is arranged parallel to the input shaft; the driven gear is fixed to the output shaft and meshes with the driving gear; the planetary gear set includes a first rotating element, a second rotating element and a third rotating element, wherein the first rotating element is fixedly connected to the input shaft, the second rotating element is fixedly connected to the driving gear, and the rotation of the third rotating element is constrained; the friction clutch is configured to selectively connect the input shaft to the driving gear; the constraint device is arranged on the third rotating element to achieve two states, so that the unidirectional rotation of the third rotating element of the planetary gear set is constrained or the bidirectional rotation of the third rotating element of the planetary gear set is constrained.

[0008] The restraining device may include: a one-way clutch and a dog clutch, wherein the one-way clutch is installed to selectively restrain the unidirectional rotation of the third rotating element of the planetary gear set; the dog clutch is installed to selectively connect the third rotating element to the transmission housing to restrain the bidirectional rotation of the third rotating element of the planetary gear set.

[0009] The tooth clutch may include: a fixed shaft, a hub, a clutch gear and a sleeve, wherein the fixed shaft has an end portion fixed to the transmission housing so as to be coaxial with the input shaft; the hub is connected to the third rotating element of the planetary gear set in a state rotatable around the fixed shaft; the clutch gear is fixed to the transmission housing; the sleeve is configured to slide linearly on the hub along the axial direction of the fixed shaft to selectively connect the hub to the clutch gear.

[0010] In a one-way clutch, the inner race may be mounted on a stationary shaft and the outer race may be mounted on a hub.

[0011] In the planetary gear set, the first rotation element may be a sun gear, the second rotation element may be a planet carrier, and the third rotation element may be a ring gear.

[0012] The output shaft may include an output gear; the ring gear of the differential may mesh with the output gear.

[0013] The friction clutch may be configured as a normally closed clutch that transmits power in a closed state, with a separate operating force applied to the clutch.

[0014] The methods and apparatus of the present invention have other features and advantages that will be apparent from or will be described in detail in the accompanying drawings and subsequent detailed descriptions incorporated herein, which together serve to explain the specific principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram illustrating an exemplary embodiment of a power train for an electric vehicle according to various exemplary embodiments of the present invention.

[0016] Figure 2 For example, Figure 1 Schematic diagram of the process of the power train shifting from first gear to second gear.

[0017] Figure 3 For example, Figure 1 Schematic diagram of the process of the powertrain shifting from second gear to first gear.

[0018] Figure 4 For example, Figure 1Schematic diagram of a powertrain achieving first gear through a dog clutch.

[0019] Figure 5 To illustrate the Figure 1 Schematic diagram of the powertrain realizing the parking function.

[0020] It should be understood that the accompanying drawings are not necessarily drawn to scale, but rather show a somewhat simplified representation of various features illustrating the basic principles of the invention. The specific design features of the present invention as incorporated herein (including, for example, specific dimensions, orientations, locations, and shapes) will be determined in part by the specific intended application and use environment.

[0021] In the figures, like reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION

[0022] Reference will now be made in detail to various embodiments of the present invention, examples of which are presented in the accompanying drawings and described below. Although the present invention will be described in conjunction with exemplary embodiments of the present invention, it should be understood that this description is not intended to limit the present invention to those exemplary embodiments. On the other hand, the present invention is intended to cover not only the exemplary embodiments of the present invention, but also various alternative forms, modifications, equivalent forms and other embodiments that may be included within the spirit and scope of the present invention as defined by the appended claims.

[0023] refer to Figure 1 According to various exemplary embodiments of the present invention, a powertrain for an electric vehicle includes: an input shaft IN, a driving gear, an output shaft OUT, a driven gear G2, a planetary gear set PG, a friction clutch CL and a constraint device; the input shaft IN is connected to the motor M; the driving gear is rotatably mounted on the input shaft IN; the output shaft OUT is mounted in parallel with the input shaft IN; the driven gear G2 is constrained to the output shaft OUT and meshes with the driving gear G1; the planetary gear set PG includes three rotating elements, a first rotating element and a second rotating element of which are respectively connected to the input shaft IN and the driving gear G1, and the rotation of the third rotating element is constrained; the friction clutch CL is installed for adjustment between the input shaft IN and the driving gear G1; the constraint device is provided on the third rotating element to realize two states, so that the third rotating element of the planetary gear set PG can be constrained in either one direction or in both directions.

[0024] That is, in various exemplary embodiments of the present invention, the power of the motor M provided to the input shaft IN is output to the output shaft OUT via the drive gear G1 and the driven gear G2 after shifting through the planetary gear set PG, and the planetary gear set PG can achieve a state in which the power of the input shaft IN is transmitted to the drive gear G1 after deceleration and a state in which the power of the input shaft IN is completely transmitted to the drive gear G1, thereby achieving a total of two gear ratios.

[0025] The restraining device is used to restrain the third rotational element of the planetary gear set PG to achieve the first gear state. In various exemplary embodiments of the present invention, the restraining device includes a one-way clutch OWC and a dog clutch DC. The one-way clutch OWC is installed to restrain only unidirectional rotation of the third rotational element of the planetary gear set PG. The dog clutch DC is installed to connect the third rotational element to the transmission case CS to restrain bidirectional rotation of the third rotational element of the planetary gear set PG.

[0026] The tooth clutch DC includes: a fixed shaft FS, a hub HB, a clutch gear CG and a sleeve SB; the fixed shaft FS has one end fixed to the transmission case CS so as to be coaxial with the input shaft IN; the hub HB is connected to the third rotation element of the planetary gear set PG in a rotatable state around the fixed shaft FS; the clutch gear CG is fixed to the transmission case CS; the sleeve SB is configured to slide linearly on the hub HB in the axial direction of the fixed shaft FS to connect the hub HB to the clutch gear CG.

[0027] Thus, when the sleeve SB is connected to the clutch gear CG, the hub HB is connected and fixed to the clutch gear CG, and as a result, the bidirectional rotation of the third rotation element of the planetary gear set PG is restricted.

[0028] Meanwhile, in the one-way clutch OWC, the inner ring is arranged on the fixed shaft FS, and the outer ring is arranged on the hub HB.

[0029] Therefore, even in a state where the dog clutch DC is not engaged, the one-way clutch OWC allows the hub HB to rotate freely in one direction, but is restricted from rotating in the opposite direction.

[0030] Here, when the power train according to various exemplary embodiments of the present invention achieves the first forward gear, the one-way clutch OWC is installed in such a direction that rotations of the hub HB and the third rotation element of the planetary gear set PG are restricted.

[0031] In various exemplary embodiments of the present invention, in the planetary gear set PG, the first rotation element is the sun gear S, the second rotation element is the planet carrier C, and the third rotation element is the ring gear R.

[0032] Thus, the input shaft IN is directly connected to the sun gear S, the drive gear G1 is directly connected to the carrier C, the hub HB of the dog clutch DC is directly connected to the ring gear R, and the friction clutch CL is installed to connect the sun gear S and the carrier C to each other.

[0033] The output shaft OUT includes an output gear OG, and the ring gear RG of the differential device DF is meshed with the output gear OG to output power to the driving wheels.

[0034] Meanwhile, the friction clutch CL is configured as a normally closed type clutch that transmits power in a closed state unless a separate operating force is applied to the clutch.

[0035] refer to Figure 2 , a process of shifting the power transmission system from the first gear to the second gear in the above embodiment will be described.

[0036] exist Figure 2 The left side of the diagram shows the first gear state of the powertrain. This state disengages both the dog clutch DC and the friction clutch CL. In this state, the power of the motor M is transmitted to the sun gear S via the input shaft IN. This power is then reduced in speed and transferred to the drive gear G1 via the planetary carrier C. The power of the drive gear G1 is then transferred to the output shaft OUT via the driven gear G2. The output gear OG then drives the ring gear RG of the differential DF, transmitting the power to the drive wheels.

[0037] In this case, the ring gear R needs to be kept stationary so that the power transmitted to the input shaft IN of the sun gear S can be transmitted to the carrier C and the drive gear G1 after being reduced in speed. At this time, the one-way clutch OWC can keep the ring gear R stationary.

[0038] That is, the ring gear R is restricted from rotating in the direction opposite to the rotation direction of the sun gear S or the planetary carrier C by the one-way clutch OWC, and the ring gear R rotates freely in the same direction as the rotation direction of the sun gear S or the planetary carrier C.

[0039] In order to shift to the second gear in the above state, Figure 2 As shown in the middle part of , when the friction force of the friction clutch CL begins to increase, as shown in Figure 2 As shown in the lower schematic diagram of , the speed of the sun gear S decreases, while the speed of the ring gear R begins to increase.

[0040] When the friction clutch CL is fully engaged, as Figure 2As shown on the right side of the figure, the sun gear S and the planetary carrier C are connected, and the planetary gear set PG is integrated. This is the same as the state in which the drive gear G1 is fixed integrally to the input shaft IN. Therefore, the power of the input shaft IN is completely transmitted to the drive gear G1, thus entering the second gear state.

[0041] That is, when shifting from the first gear to the second gear, the friction force of the friction clutch CL continues to increase, thereby performing smooth shifting without torque interruption.

[0042] Figure 3 The process of shifting from the second gear state to the first gear state is shown. Figure 3 When the second gear position shown on the left side is released, Figure 3 As shown in the middle part of , the speed of the sun gear S gradually increases, and the speed of the ring gear R gradually decreases accordingly, as shown in Figure 3 As shown on the right side of , the ring gear R is fixed, and the power of the sun gear S is decelerated by the planetary carrier C and transmitted to the drive gear G1, thereby completing the shift to the first gear state.

[0043] Of course, in the first gear state, the ring gear R is restrained from rotating in the opposite direction by the one-way clutch OWC. Similarly, when shifting from the second gear to the first gear, by gradually releasing the friction clutch CL, the shift can be smoothly performed without torque interruption, and there is no need to perform active control to restrain the ring gear R, thereby facilitating control and facilitating smooth shifting.

[0044] Here, even in Figure 4 In the case where the dog clutch DC is engaged, the first gear state of the powertrain is also achieved. In this state, regenerative braking can be achieved, and a reverse gear can be easily achieved by rotating the motor M in the opposite direction.

[0045] That is, in order to easily and smoothly perform the shift from the first gear to the second gear, the dog clutch DC needs to be released and the first gear state of the ring gear R needs to be constrained by the one-way clutch OWC. For reverse driving or regenerative braking, the dog clutch DC needs to be engaged and the one-way clutch OWC needs to be in the first gear state with free rotation constrained.

[0046] at the same time, Figure 5 The parking function is shown to be implemented via the powertrain.

[0047] That is, since the friction clutch CL is configured as a normally closed clutch, when the powertrain achieves the first gear with the dog clutch DC engaged, and then the operating force applied to the clutch CL is released so that the vehicle enters the parking state, the friction clutch CL is engaged, and accordingly, Figure 5As shown on the left side of , the output shaft OUT is fixed to the transmission case CS via the driven gear G2, the drive gear G1, the planetary gear set PG and the dog clutch DC in sequence, thereby achieving a parking state in which the output shaft OUT is prevented from rotating.

[0048] Conventionally, a parking state is achieved by engaging a parking wedge as a parking mechanism, resulting in problems such as noise or shock. In contrast, according to various exemplary embodiments of the present invention, when a parking state is achieved by releasing the operating force of the friction clutch CL of the normally closed clutch in the first gear state based on the dog clutch DC, a smooth shift to the parking state can be achieved without any noise or shock.

[0049] Of course, in order to release the parking state and drive the vehicle, as Figure 5 As shown on the right side of , the friction clutch CL can be released to switch to the first gear state, and then the motor M can be driven to drive the vehicle in the first gear.

[0050] According to various exemplary embodiments of the present invention, two gear ratios can be set in a relatively simple configuration, thereby reducing the volume of the motor used and the weight of the vehicle, changing the operating point of the motor, and entering a neutral state in which the motor is not connected to the drive wheels, thereby improving the energy efficiency of the vehicle.

[0051] Furthermore, the parking function can be achieved by interlocking without having a separate parking mechanism, thereby reducing the number of components and contributing to reducing the weight of the vehicle.

[0052] For convenience of explanation and precise definition in the appended claims, the terms "upper," "lower," "inner," "outer," "above," "below," "upward," "downward," "front," "back," "inner," "external," "inner," "external," "inner," "external," "inside," "outside," "forward," and "rearward" are used to describe features of the exemplary embodiments with reference to the positions of such features as shown in the drawings. It should be further understood that the term "connect" or its derivatives refers to both direct and indirect connections.

[0053] Furthermore, the term "fixedly connected" means that fixedly connected members always rotate at the same speed. Furthermore, the term "selectively connectable" means that "when the selectively connectable members are not engaged with each other, the selectively connectable members rotate separately, when the selectively connectable members are engaged with each other, the selectively connectable members rotate at the same speed, and when at least one selectively connectable member is a fixed member and the remaining selectively connectable members are engaged to the fixed member, the selectively connectable members are fixed."

[0054] The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. The foregoing descriptions are not intended to be exhaustive, nor are they intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described in order to explain the specific principles of the invention and its practical application, thereby enabling others skilled in the art to realize and utilize the various exemplary embodiments of the invention and its various alternative forms and modifications. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A powertrain device for a vehicle, the powertrain device comprising: an input shaft to which the electric motor is fixedly connected; a drive gear rotatably mounted on the input shaft; an output shaft arranged parallel to the input shaft; a driven gear fixed to the output shaft and meshing with the drive gear; a planetary gear set including a first rotation element, a second rotation element, and a third rotation element, wherein the first rotation element is fixedly connected to the input shaft; The second rotating element is engaged with the first rotating element, and the second rotating element is fixedly connected to the driving gear; the third rotating element is engaged with the second rotating element, and the rotation of the third rotating element is restricted; a clutch mounted between the input shaft and the drive gear and configured to selectively connect the input shaft to the drive gear; as well as a constraint device provided on the third rotating element to realize a first state in which the unidirectional rotation of the third rotating element of the planetary gear set is constrained, or a second state in which the bidirectional rotation of the third rotating element of the planetary gear set is constrained, Wherein, the restraint device includes: a one-way clutch installed to selectively restrict one-way rotation of the third rotation element of the planetary gear set; and a dog clutch installed to selectively connect the third rotating element to the transmission case to restrict bidirectional rotation of the third rotating element of the planetary gear set, The dog clutch comprises: a fixed shaft having an end fixed to the transmission housing; a hub portion connected to the third rotation element of the planetary gear set in a state rotatable about the fixed axis; a clutch gear fixed to the transmission case; and The sleeve is arranged to slide linearly on the hub in the axial direction of the fixed shaft to selectively connect the hub to the clutch gear.

2. The powertrain device for a vehicle according to claim 1, wherein The fixed shaft is coaxial with the input shaft.

3. The powertrain device for a vehicle according to claim 1, wherein The one-way clutch is mounted on the fixed shaft of the tooth clutch.

4. The powertrain device for a vehicle according to claim 1, wherein The hub and the third rotation element of the planetary gear set are constrained from rotating in one direction by the one-way clutch.

5. The powertrain device for a vehicle according to claim 1, wherein In a one-way clutch, the inner ring is arranged on a fixed shaft and the outer ring is arranged on a hub.

6. The powertrain device for a vehicle according to claim 1, wherein In the planetary gear set, the first rotating element is the sun gear, the second rotating element is the planet carrier, and the third rotating element is the ring gear.

7. The powertrain apparatus for a vehicle according to claim 1, further comprising an output gear fixed to the output shaft; in, The differential's ring gear meshes with the output gear.

8. The powertrain device for a vehicle according to claim 1, wherein The clutch is a normally closed type clutch to transmit power in a closed state unless a separate operating force is applied to the clutch.

Images