Multi-speed transmission

Abstract

The present invention relates to the technical field of motor vehicle transmissions, and provides a multi-stage transmission. The multi-stage transmission comprises a housing, an input shaft, an output shaft, a brake, four planetary row assemblies and four clutches; the input shaft is connected to the second clutch and the second planet carrier; the brake is fixed to the inner wall of the housing and is connected to the first sun gear and the second sun gear through the first shaft; the first planet carrier is connected to the first clutch through the second shaft, and the first ring gear is arranged on the inner wall of the housing; the second ring gear is connected to the third sun gear through the third shaft; the third planet carrier is connected to the third clutch and the fourth clutch through the fourth shaft and the fifth shaft respectively; the third ring gear is connected to the second clutch through the sixth shaft; the fourth sun gear is connected to the sixth shaft, the fourth planet carrier is connected to the third clutch through the seventh shaft, and the output shaft is connected to the fourth planet carrier in a transmission connection; the fourth ring gear is connected to the first clutch through the eighth shaft.

Description

Technical Field

[0001] The present invention relates to the technical field of motor vehicle transmissions, and in particular to a multi-stage transmission. Background Art

[0002] The automobile transmission is a set of speed-changing devices used to coordinate the engine speed and the actual driving speed of the wheels, so as to bring out the best performance of the engine. The transmission can produce different speed ratios between the engine and the wheels during the driving process of the car, and realize the transmission of speeds in different gears.

[0003] There are two types of transmissions: manual and automatic. Manual transmissions are mainly composed of gears and shafts, and produce speed and torque changes through different gear combinations; while automatic transmissions AT are composed of a torque converter, planetary gears and a hydraulic control system, and achieve the purpose of speed and torque changes through hydraulic transmission and gear combinations.

[0004] Among them, the automatic transmission has the advantages of driving comfort and reducing driver fatigue, and has become a development direction of modern car configuration. The automatic transmission uses a planetary gear mechanism to change speed. It can automatically change speed according to the degree of the accelerator pedal and the speed of the vehicle. The driver only needs to operate the accelerator pedal to control the speed of the vehicle. The driver can concentrate on the road traffic without being confused by the gear shift.

[0005] In the commonly used transmission, the transmission includes multiple forward gears and one reverse gear, and in the forward direction, the transmission can have a very high starting speed ratio. However, since there are many components to realize the shifting function in the current transmission, the manufacturing cost is relatively high, which is not conducive to cost compression, and the connection method between the components increases the damage of the transmission element, reducing the safety factor and service life of the transmission element. Summary of the invention

[0006] In order to solve the above technical problem or at least partially solve the above technical problem, the present invention provides a multi-speed transmission.

[0007] The multi-speed transmission comprises a housing, an input shaft, an output shaft, a first planetary gear assembly, a second planetary gear assembly, a third planetary gear assembly, a fourth planetary gear assembly, a brake, a first clutch, a second clutch, a third clutch and a fourth clutch;

[0008] The first planetary row assembly includes a first sun gear, a first planetary gear, a first planet carrier and a first ring gear; the second planetary row assembly includes a second sun gear, a second planetary gear, a second planet carrier and a second ring gear; the third planetary row assembly includes a third sun gear, a third planetary gear, a third planet carrier and a third ring gear; the fourth planetary row assembly includes a fourth sun gear, a fourth planetary gear, a fourth planet carrier and a fourth ring gear;

[0009] The input rotating shaft is connected to the second clutch and the second planet carrier respectively;

[0010] The brake is fixedly mounted on the inner wall of the housing, and the brake is connected to the first sun gear and the second sun gear via a first rotating shaft;

[0011] The first planet carrier is connected to the first clutch via a second rotating shaft, and the first ring gear is fixedly arranged on the inner wall of the housing;

[0012] The second ring gear is connected to the third sun gear via a third rotating shaft; one side of the third planet carrier is connected to the third clutch via a fourth rotating shaft, and the other side of the third planet carrier is connected to the fourth clutch via a fifth rotating shaft; the third ring gear is connected to the second clutch via a sixth rotating shaft; and the fourth clutch is disposed on the sixth rotating shaft;

[0013] The fourth sun gear is connected to the sixth shaft, the fourth planetary carrier is connected to the third clutch through the seventh shaft, the output shaft is transmission-connected to the fourth planetary carrier; the fourth ring gear is connected to the first clutch through the eighth shaft; the input shaft and the output shaft are coaxially arranged.

[0014] Optionally, the output shaft is connected to a seventh shaft arranged on the fourth planetary carrier.

[0015] Optionally, the first planetary gear assembly, the second planetary gear assembly, the third planetary gear assembly and the fourth planetary gear assembly are arranged in sequence along a direction toward the output shaft.

[0016] Optionally, the multi-speed transmission includes eight forward gears and one reverse gear:

[0017] A first forward gear is achieved by closing the brake, the first clutch and the second clutch;

[0018] A second forward gear is achieved by closing the brake, the first clutch and the fourth clutch;

[0019] A third forward gear is achieved by closing the first clutch, the second clutch and the fourth clutch;

[0020] A fourth forward gear is achieved by closing the first clutch, the third clutch and the fourth clutch;

[0021] A fifth forward gear is achieved by closing the first clutch, the second clutch and the third clutch;

[0022] A sixth forward gear is achieved by closing the second clutch, the third clutch and the fourth clutch;

[0023] A seventh forward gear is achieved by closing the brake, the second clutch and the third clutch;

[0024] An eighth forward gear is achieved by closing the brake, the third clutch and the fourth clutch;

[0025] Reverse gear is achieved by closing the brake, the first clutch and the third clutch.

[0026] Optionally, the multi-stage transmission further comprises a hydraulic torque converter disposed in the housing, one end of the hydraulic torque converter being connected to the engine, and the other end of the hydraulic torque converter being connected to the input shaft.

[0027] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0028] The multi-stage transmission provided by the present application can be applied to automobiles. During the use of the multi-stage transmission, the driver can achieve the switching of eight forward gears and one reverse gear by changing the matching relationship between the five shift components and the four planetary gears. Through the matching of the above components, the fatigue safety factor of some gears is increased, the damage rate of some bearings is reduced, and the safety factor and service life of the multi-stage transmission are increased. In addition, this matching method effectively reduces the number of internal components of the multi-stage transmission and reduces the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] Figure 1 is a schematic structural diagram of a multi-stage transmission in one embodiment of the present invention;

[0032] Figure 2 is a cross-sectional view of a multi-stage transmission according to one embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the shifting logic of a multi-speed transmission in one embodiment of the present invention.

[0034] Reference numerals:

[0035] P1, first planetary row assembly; 10, first sun gear; 11, first planet carrier; 12, first ring gear; P2, second planetary row assembly; 20, second sun gear; 21, second planet carrier; 22, second ring gear; P3, third planetary row assembly; 30, third sun gear; 31, third planet carrier; 32, third ring gear; P4, fourth planetary row assembly; 40, fourth sun gear; 41, fourth planet carrier; 42, fourth ring gear; 50, housing; 51, input shaft; 52, output shaft; 60, brake; 61, first clutch; 62, second clutch; 63, third clutch; 64, fourth clutch; 71, first shaft; 72, second shaft; 73, third shaft; 74, fourth shaft; 75, fifth shaft; 76, sixth shaft; 77, seventh shaft; 78, eighth shaft. DETAILED DESCRIPTION

[0036] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0038] like Figure 1As shown, the multi-stage transmission provided in the embodiment of the present application includes a housing 50, an input shaft 51, an output shaft 52, a first planetary gear assembly P1, a second planetary gear assembly P2, a third planetary gear assembly P3, a fourth planetary gear assembly P4, a brake 60, a first clutch 61, a second clutch 62, a third clutch 63 and a fourth clutch 64. Among them, the brake 60 is used to connect the rotating shaft, and the axial degree of freedom of the rotating shaft can be controlled by the brake 60. Specifically, when the brake 60 is closed, the rotating shaft connected to the brake 60 is locked, and the rotating shaft will not rotate along its own circumferential direction; when the brake 60 is opened, the rotation of the rotating shaft connected thereto is not restricted. The clutch in the transmission is used to connect two rotating shafts. When the clutch is closed, the two rotating shafts connected to the clutch can rotate synchronously; when the clutch is separated, the two rotating shafts connected to the clutch can rotate relative to the clutch.

[0039] The first planetary row assembly P1 includes a first sun gear 10, a first planetary gear, a first planetary carrier 11 and a first ring gear 12; the second planetary row assembly P2 includes a second sun gear 20, a second planetary gear, a second planetary carrier 21 and a second ring gear 22; the third planetary row assembly P3 includes a third sun gear 30, a third planetary gear, a third planetary carrier 31 and a third ring gear 32; the fourth planetary row assembly P4 includes a fourth sun gear 40, a fourth planetary gear, a fourth planetary carrier 41 and a fourth ring gear 42. Among them, the transmission process and transmission principle of the planetary row assembly are well known to those skilled in the art, so no detailed description is given.

[0040] like Figure 1 As shown, the input shaft 51 is respectively connected to the second clutch 62 and the second planet carrier 21. Specifically, the second planet carrier 21 can be driven to rotate by the rotation of the input shaft 51. When the second clutch 62 is closed, the input shaft 51 can drive another rotating shaft connected to the second clutch 62 to rotate; when the second clutch 62 is opened, the input shaft 51 rotates relative to the second clutch 62.

[0041] The brake 60 is fixedly mounted on the inner wall of the housing 50, and the brake 60 is connected to the first sun gear 10 and the second sun gear 20 through the first rotating shaft 71. The rotation or locking of the first rotating shaft 71 can be controlled by opening or closing the brake 60. Specifically, when the brake 60 is closed, the first rotating shaft 71 will not rotate, and therefore, the first sun gear 10 and the second sun gear 20 will not rotate. When the brake 60 is opened, the first rotating shaft 71 can rotate relative to the brake 60, and then the first sun gear 10 and the second sun gear 20 connected thereto can both rotate.

[0042] The first planet carrier 11 is connected to the first clutch 61 through the second rotating shaft 72, and the first ring gear 12 is fixedly arranged on the inner wall of the housing 50. Since the first ring gear 12 is fixed on the inner wall of the housing 50, the first ring gear 12 will not rotate. When the input rotating shaft 51 drives the second planet carrier 21 to rotate, if the brake 60 is closed, the first rotating shaft 71 will not rotate, and accordingly, the first sun gear 10, the first planet carrier 11 and the second rotating shaft 72 will not rotate; if the brake 60 is opened, the second sun gear 20 and the first rotating shaft 71 are driven to rotate by the rotation of the second planet carrier 21, and then the first sun gear 10 is driven to rotate by the first rotating shaft 71, and then the first planet carrier 11 and the second rotating shaft 72 are driven to rotate by the first sun gear 10.

[0043] The second ring gear 22 is connected to the third sun gear 30 through the third rotating shaft 73, and the third sun gear 30 can be driven to rotate by the rotation of the second ring gear 22. One side of the third planetary carrier 31 is connected to the third clutch 63 through the fourth rotating shaft 74, and the other side of the third planetary carrier 31 is connected to the fourth clutch 64 through the fifth rotating shaft 75. The third ring gear 32 is connected to the second clutch 62 through the sixth rotating shaft 76, and the connection or disconnection of the input rotating shaft 51 and the sixth rotating shaft 76 is controlled by the closing and separation of the second clutch 62. That is, when the second clutch 62 is closed, the input rotating shaft 51 rotates synchronously with the sixth rotating shaft 76, and when the second clutch 62 is opened, the input rotating shaft 51 and the sixth rotating shaft 76 can rotate relative to each other. The fourth clutch 64 is arranged on the sixth rotating shaft 76. Through this design, when the fourth clutch 64 is closed, the third planetary carrier 31 and the third ring gear 32 are connected as a whole, so that the fourth rotating shaft 74 and the sixth rotating shaft 76 have the same rotation speed. When the fourth clutch 64 is opened, the third planetary carrier 31 and the third ring gear 32 are separated, and the rotation speeds of the third planetary carrier 31 and the third ring gear 32 are different.

[0044] The fourth sun gear 40 is connected to the sixth rotating shaft 76, and the fourth sun gear 40 is driven to rotate by the rotation of the sixth rotating shaft 76. The fourth planetary carrier 41 is connected to the third clutch 63 through the seventh rotating shaft 77, and the connection relationship between the fourth rotating shaft 74 and the seventh rotating shaft 77 can be controlled by the third clutch 63. Specifically, when the third clutch 63 is closed, the fourth rotating shaft 74 and the seventh rotating shaft 77 rotate synchronously; when the third clutch 63 is opened, the fourth rotating shaft 74 and the seventh rotating shaft 77 can rotate relatively. The output rotating shaft 52 is transmission-connected to the fourth planetary carrier 41, and the output rotating shaft 52 is driven to rotate by the rotation of the fourth planetary carrier 41. Preferably, the output rotating shaft 52 is connected to the seventh rotating shaft 77 provided on the fourth planetary carrier 41, which saves equipment cost and reduces occupied space. Specifically, the seventh rotating shaft 77 is arranged on the fourth planetary carrier 41, one end of the seventh rotating shaft 77 is connected to the output rotating shaft 52, and the other end is connected to the third clutch 63. Alternatively, a seventh rotating shaft 77 is provided at both ends of the fourth planetary carrier 41, wherein the output end of one of the seventh rotating shafts 77 is connected to the third clutch 63, and the output end of the other seventh rotating shaft 77 is connected to the output rotating shaft 52. The fourth ring gear 42 is connected to the first clutch 61 through the eighth rotating shaft 78, and the connection between the second rotating shaft 72 and the eighth rotating shaft 78 is controlled by the first clutch 61. Specifically, when the first clutch 61 is closed, the second rotating shaft 72 and the eighth rotating shaft 78 rotate synchronously; when the first clutch 61 is opened, the second rotating shaft 72 and the eighth rotating shaft 78 both rotate relative to the first clutch 61. The coaxial arrangement of the input rotating shaft 51 and the output rotating shaft 52 can effectively reduce the occupied space of the multi-stage transmission.

[0045] Combination Figure 1 and Figure 2 As shown, the first planetary gear assembly P1, the second planetary gear assembly P2, the third planetary gear assembly P3 and the fourth planetary gear assembly P4 are arranged in sequence along the direction toward the output shaft 52, which is convenient for the installation of the multi-stage transmission. At the same time, the arrangement of the planetary gear assembly of the present application is not limited to this type. The staff can reasonably adjust the positions of the first planetary gear assembly P1, the second planetary gear assembly P2, the third planetary gear assembly P3 and the fourth planetary gear assembly P4 according to the size of the internal space of the housing 50 and the distance relationship between the mechanism components.

[0046] The multi-stage transmission provided by the present application can realize three driving modes: pure electric, engine driven, and hybrid. During the use of the multi-stage transmission, the driver can switch between eight forward gears and one reverse gear by changing the matching relationship between the five shift components and the four planetary gears. Through the matching of the above components, the fatigue safety factor of some gears is increased, the damage rate of some bearings is reduced, and the safety factor and service life of the multi-stage transmission are increased. In addition, this matching method effectively reduces the number of internal components of the multi-stage transmission and reduces manufacturing costs.

[0047] The multi-stage transmission not only includes the above-mentioned planetary transmission mechanism, but also includes a torque converter, a dual-mass flywheel, a hybrid module, a hydraulic system, a shift unit, a hydraulic pump, and an electric pump. The torque converter is arranged in the housing 50, one end of the torque converter is connected to the engine, and the other end is connected to the input shaft 51. The hybrid module is connected to the dual-mass flywheel and the input end of the input shaft 51 respectively. The hydraulic system provides hydraulic pressure for the brake 60, the first clutch 61, the second clutch 62, the third clutch 63 and the fourth clutch 64, thereby controlling their opening or closing, and in addition, it can also provide lubrication function. Since the above-mentioned components are relatively conventional components in the multi-stage transmission, no further description is given.

[0048] like Figure 3 As shown, the multi-speed transmission includes eight forward gears and one reverse gear. The shifting of different gears can be achieved through the different matching relationships of five shifting components, four planetary gears and multiple shafts. The specific shifting operation is as follows:

[0049] First forward gear: close the brake 60, the first clutch 61 and the second clutch 62; release the third clutch 63 and the fourth clutch 64.

[0050] Since the brake 60 is closed, the first rotating shaft 71 will not rotate, so that the first planetary carrier 11 and the second rotating shaft 72 will not rotate. Since the first clutch 61 is closed, the second rotating shaft 72 is connected to the eighth rotating shaft 78, so the eighth rotating shaft 78 will not rotate. At the same time, since the third clutch 63 and the fourth clutch 64 are open, the power cannot be transmitted to the output rotating shaft 52 through the third planetary carrier 31. Because the second clutch 62 is closed, the power can be transmitted from the input rotating shaft 51 to the sixth rotating shaft 76, and the fourth sun gear 40 is driven to rotate through the sixth rotating shaft 76, thereby driving the output rotating shaft 52 to rotate.

[0051] Second forward gear: close the brake 60, the first clutch 61 and the fourth clutch 64; release the second clutch 62 and the third clutch 63.

[0052] Since the second clutch 62 is open, the input shaft 51 cannot directly drive the sixth shaft 76 to rotate. The third clutch 63 is disconnected, so the seventh shaft 77 cannot be driven to rotate through the fourth shaft 74. Because the brake 60 and the first clutch 61 are closed, it can be known from the principle of the first forward gear that the first shaft 71 and the eighth shaft 78 will not rotate. The power of the input shaft 51 is transmitted to the third shaft 73 through the second planetary gear assembly P2. Because the fourth clutch 64 is closed, the fourth shaft 74 and the fifth shaft 75 are driven to rotate synchronously through the rotation of the third sun gear 30. Because the third clutch 63 is released, the third planetary gear assembly P3 transmits power to the third shaft 73, and then transmits it to the output shaft 52 through the fourth planetary gear assembly P4 to complete the power transmission.

[0053] Third forward gear: close the first clutch 61 , the second clutch 62 and the fourth clutch 64 ; release the brake 60 and the third clutch 63 .

[0054] The power is inputted from the input shaft 51. Because the brake 60 is disconnected, the first shaft 71 can rotate along with the second sun gear 20, and then the first sun gear 10 is driven to rotate through the first shaft 71. The first sun gear 10 then drives the first planet carrier 11 and the second shaft 72 to rotate. Because the first clutch 61 is closed, the second shaft 72 can drive the eighth shaft 78 to rotate, so the power can be transmitted to the fourth ring gear 42. Because the second clutch 62 and the fourth clutch 64 are closed, the power can be transmitted to the sun gear of the third planetary gear assembly P3 through the sixth shaft 76, and then the output shaft 52 is driven to rotate, completing the power transmission.

[0055] Fourth forward gear: close the first clutch 61, the third clutch 63 and the fourth clutch 64; release the brake 60 and the second clutch 62.

[0056] The power is input from the input shaft 51. Because the brake 60 is disconnected and the first clutch 61 is closed, it can be known from the principle of the third forward gear that the power of the input shaft 51 can be transmitted to the third ring gear 32. Because the fourth clutch 64 is closed, the power can be transmitted to the sixth shaft 76, and then to the third sun gear 30, so that the output shaft 52 rotates.

[0057] Fifth forward gear: close the first clutch 61 , the second clutch 62 and the third clutch 63 ; release the brake 60 and the fourth clutch 64 .

[0058] Power is input from the input shaft 51. Because the brake 60 is disconnected and the first clutch 61 is closed, the power can be transmitted to the third ring gear 32. Because the second clutch 62 is closed, the power can be directly transmitted to the sixth shaft 76 through the input shaft 51, and then transmitted to the third ring gear 32. Because the fourth clutch 64 is disconnected and the third clutch 63 is closed, the third planet carrier 31 can output power to the output shaft 52.

[0059] Sixth forward gear: close the second clutch 62 , the third clutch 63 and the fourth clutch 64 ; release the brake 60 and the first clutch 61 .

[0060] Since the second clutch 62 is closed, the power of the input shaft 51 can be directly transmitted to the sixth shaft 76, and then to the third ring gear 32. Since the brake 60 and the first clutch 61 are both open, the power cannot be transmitted to the fourth ring gear 42 through the first planetary carrier 11. Since the third clutch 63 is closed, the third planetary carrier 31 can transmit the power to the output shaft 52, and since the fourth clutch 64 is closed, the rotation speeds of the third ring gear 32 and the third planetary carrier 31 are the same.

[0061] Seventh forward gear: close the brake 60, the second clutch 62 and the third clutch 63; release the first clutch 61 and the fourth clutch 64.

[0062] The power is input by the input shaft 51. Because the brake 60 is closed and the first clutch 61 is open, the first shaft 71 does not rotate. At the same time, the power of the input shaft 51 is transmitted to the second ring gear 22 through the second planetary carrier 21, and then the power is transmitted to the third sun gear 30. Because the second clutch 62 and the third clutch 63 are closed, the power of the input shaft 51 can be transmitted to the third ring gear 32 through the sixth shaft 76, and then the power is transmitted to the output shaft 52 through the second planetary carrier 21.

[0063] Eighth forward gear: close the brake 60, the third clutch 63 and the fourth clutch 64; release the first clutch 61 and the second clutch 62.

[0064] The power is inputted from the input shaft 51. Because the brake 60 is closed, the first shaft 71 does not rotate. The power is transmitted from the second ring gear 22 of the second planetary gear assembly P2 to the third planetary gear assembly P3, and then to the output shaft 52 through the planet carrier of the second planetary gear assembly P2.

[0065] Reverse gear (R gear): close the brake 60, the first clutch 61 and the third clutch 63; release the second clutch 62 and the fourth clutch 64.

[0066] The power is inputted from the input shaft 51. Because the brake 60 and the first clutch 61 are closed, the eighth shaft 78 and the first shaft 71 do not rotate. The power is transmitted from the second ring gear 22 of the second planetary gear assembly P2 to the third planetary gear assembly P3, and then transmitted from the third planetary carrier 31 of the third planetary gear assembly P3 to the output shaft 52.

[0067] The first sun gear 10 and the second sun gear 20 of the present application adopt a left-hand design, and the third sun gear 30 and the fourth sun gear 40 adopt a right-hand design. Taking the second forward gear as an example, the force analysis of the structure of the corresponding components is carried out, which is as follows:

[0068] When the vehicle is in the second forward gear, the brake 60, the first clutch 61 and the fourth clutch 64 are closed; the second clutch 62 and the third clutch 63 are released. Figure 1 and Figure 2 As shown, during the operation of the transmission, the input shaft 51 rotates and drives the second planetary carrier 21 to rotate. Since the second sun gear 20 is stationary, the second planetary carrier 21 drives the second ring gear 22 to rotate. The second ring gear 22 is connected to the third sun gear 30, and since the fourth clutch 64 is closed, the third planetary row assembly P3 is integrated, that is, the rotation speeds of the third sun gear 30, the third planetary carrier 31 and the third ring gear 32 are all the same. The third ring gear 32 drives the fourth sun gear 40 to rotate. Since the brake 60 and the first clutch 61 are closed, the fourth ring gear 42 does not rotate, and then drives the fourth planetary carrier 41 to rotate through the fourth sun gear 40.

[0069] The second gear is a forward gear, so the input shaft 51 and the output shaft 52 both rotate forward, where forward rotation refers to the direction of the input shaft 51 and the output shaft 52 when viewed from the output end of the transmission toward the input end. Since the fourth clutch 64 is closed, the fourth planetary gear assembly P4 forms power transmission, and since the fourth sun gear 40 adopts a right-hand design, the fourth sun gear 40 transmits axial force to the left. Figure 2As shown, the force direction of the fourth sun gear 40 is to the left, so the bearing on the right side of the fourth sun gear 40 and the bearing on the right side of the fourth planetary carrier 41 are not subjected to force. The axial force is transmitted to the left through the fourth sun gear 40, and then transmitted to the third sun gear 30 through the spline and the inner hub of the corresponding clutch, so that the third sun gear 30 is subjected to a left force, wherein a bearing is provided between the adjacent spline and the inner hub. On the other hand, the input shaft 51 drives the second planetary carrier 21 to rotate. Since the second sun gear 20 adopts a left-handed design, the axial force on the second sun gear 20 is to the right, and it is well known that in the planetary row, the axial forces on the sun gear and the ring gear are in opposite directions, and the axial forces on the planetary carrier are offset, so the force on the second ring gear 22 is to the left. The third sun gear 30 is connected to the second ring gear 22, so the axial force on the third sun gear 30 is to the left, and then the axial force on the third ring gear 32 is to the right. The third ring gear 32 is connected to the fourth sun gear 40. Therefore, the axial force applied by the third ring gear 32 to the fourth sun gear 40 is directed to the right, thereby offsetting part of the axial force of the fourth sun gear 40 to the left, thereby reducing the force on each bearing between the third sun gear 30 and the fourth sun gear 40.

[0070] That is, during the operation of the transmission, the power flows through the third planetary gear assembly P3, and the third planetary gear assembly P3 generates a force that balances the output of the fourth sun gear 40, thereby reducing the force on the bearing between the third planetary gear assembly P3 and the fourth planetary gear assembly P4. In addition, the bearing near the output shaft 52 of the transmission is subjected to greater force in the entire transmission. It can be seen that this design method can effectively reduce the force on this part of the bearing, thereby reducing the damage rate of the bearing.

[0071] The above-mentioned leftward and rightward directions are relative to the attached Figure 3 In the conventional transmission, the axial directions of the rotating parts are connected by bearings, so that two adjacent rotating parts can rotate relative to each other and provide axial support and axial force transmission. This connection method is common knowledge to those skilled in the art. Therefore, the bearing position disclosed in the present invention is obvious to those skilled in the art, and therefore, no further introduction is given.

[0072] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0073] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-speed transmission, characterized in that: It includes a housing, an input shaft, an output shaft, a first planetary gear assembly, a second planetary gear assembly, a third planetary gear assembly, a fourth planetary gear assembly, a brake, a first clutch, a second clutch, a third clutch and a fourth clutch; The first planetary row assembly includes a first sun gear, a first planetary gear, a first planet carrier and a first ring gear; the second planetary row assembly includes a second sun gear, a second planetary gear, a second planet carrier and a second ring gear; the third planetary row assembly includes a third sun gear, a third planetary gear, a third planet carrier and a third ring gear; the fourth planetary row assembly includes a fourth sun gear, a fourth planetary gear, a fourth planet carrier and a fourth ring gear; The input rotating shaft is connected to the second clutch and the second planet carrier respectively; The brake is fixedly mounted on the inner wall of the housing, and the brake is connected to the first sun gear and the second sun gear via a first rotating shaft; The first planet carrier is connected to the first clutch via a second rotating shaft, and the first ring gear is fixedly arranged on the inner wall of the housing; The second ring gear is connected to the third sun gear via a third rotating shaft; one side of the third planet carrier is connected to the third clutch via a fourth rotating shaft, and the other side of the third planet carrier is connected to the fourth clutch via a fifth rotating shaft; the third ring gear is connected to the second clutch via a sixth rotating shaft; and the fourth clutch is disposed on the sixth rotating shaft; The fourth sun gear is connected to the sixth shaft, the fourth planetary carrier is connected to the third clutch through the seventh shaft, the output shaft is transmission-connected to the fourth planetary carrier; the fourth ring gear is connected to the first clutch through the eighth shaft; the input shaft and the output shaft are coaxially arranged.

2. The multi-speed transmission according to claim 1, characterized in that: The output shaft is drivingly connected to a seventh shaft disposed on the fourth planetary carrier.

3. The multi-speed transmission according to claim 1, characterized in that: The first planetary gear assembly, the second planetary gear assembly, the third planetary gear assembly and the fourth planetary gear assembly are arranged in sequence along a direction toward the output shaft.

4. The multi-speed transmission according to claim 1, characterized in that: The multi-speed transmission includes eight forward gears and one reverse gear: A first forward gear is achieved by closing the brake, the first clutch and the second clutch; A second forward gear is achieved by closing the brake, the first clutch and the fourth clutch; A third forward gear is achieved by closing the first clutch, the second clutch and the fourth clutch; A fourth forward gear is achieved by closing the first clutch, the third clutch and the fourth clutch; A fifth forward gear is achieved by closing the first clutch, the second clutch and the third clutch; A sixth forward gear is achieved by closing the second clutch, the third clutch and the fourth clutch; A seventh forward gear is achieved by closing the brake, the second clutch and the third clutch; An eighth forward gear is achieved by closing the brake, the third clutch and the fourth clutch; Reverse gear is achieved by closing the brake, the first clutch and the third clutch.

5. The multi-speed transmission according to claim 1, characterized in that: The multi-stage transmission further comprises a hydraulic torque converter arranged in the housing, one end of the hydraulic torque converter is connected to the engine, and the other end of the hydraulic torque converter is connected to the input shaft.

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