CN111734797A - Multi-speed transmission - Google Patents

Abstract

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

Description

Multi-speed transmission

Technical Field

The invention relates to the technical field of motor vehicle transmissions, in particular to a multi-stage transmission.

Background

An automotive transmission is a set of transmission devices for coordinating the rotational speed of an engine and the actual driving speed of wheels, and is used for exerting the best performance of the engine. The transmission can generate different gear ratios between an engine and wheels during the running process of the automobile, and the transmission of the rotating speeds of different gears is realized.

The manual transmission mainly comprises gears and a rotating shaft, and the speed change and torque change are generated by different gear combinations; the automatic transmission AT consists of a hydraulic torque converter, a planetary gear and a hydraulic control system, and achieves the purposes of speed and torque changing through a hydraulic transmission and gear combination mode.

Among them, the automatic transmission has advantages of comfortable driving, reducing fatigue of driver, etc., and has become a development direction of modern car configuration. The automatic transmission utilizes a planetary gear mechanism to change speed, can automatically change speed according to the degree of an accelerator pedal and the change of vehicle speed, and a driver only needs to operate the accelerator pedal to control the vehicle speed, so that the driver can watch road traffic with full attention without being confused by gear shifting.

In a common transmission, the transmission includes a plurality of forward gears and a reverse gear, and the transmission can have a high start speed ratio in the forward direction. However, in the existing transmission, the number of components for realizing the gear shifting function is large, so that the manufacturing cost is high, the cost is not favorably reduced, and the connection mode among the components increases the damage of the transmission element, reduces the safety factor of the transmission element and prolongs the service life of the transmission element.

Disclosure of Invention

In order to solve the above technical problem or at least partially solve the above technical problem, the present invention provides a multistage transmission.

The multi-stage transmission comprises a shell, an input rotating shaft, an output rotating shaft, a first planet row assembly, a second planet row assembly, a third planet row assembly, a fourth planet row assembly, a brake, a first clutch, a second clutch, a third clutch and a fourth clutch;

the first planet carrier assembly comprises a first sun gear, a first planet carrier and a first ring gear; the second planet row assembly comprises a second sun gear, a second planet carrier and a second gear ring; the third planet bar assembly includes a third sun gear, a third planet carrier, and a third ring gear; the fourth planet row assembly comprises a fourth sun gear, a fourth planet carrier and a fourth gear ring;

the input rotating shaft is respectively connected with the second clutch and the second planet carrier;

the brake is fixedly arranged on the inner wall of the shell and is connected with the first sun gear and the second sun gear through a first rotating shaft;

the first planet carrier is connected with the first clutch through a second rotating shaft, and the first gear ring is fixedly arranged on the inner wall of the shell;

the second gear ring is connected with the third sun gear through a third rotating shaft; one side of the third planet carrier is connected with the third clutch through a fourth rotating shaft, and the other side of the third planet carrier is connected with the fourth clutch through a fifth rotating shaft; the third gear ring is connected with the second clutch through a sixth rotating shaft; the fourth clutch is arranged on the sixth rotating shaft;

the fourth sun gear is connected with the sixth rotating shaft, the fourth planet carrier is connected with the third clutch through a seventh rotating shaft, and the output rotating shaft is in transmission connection with the fourth planet carrier; the fourth gear ring is connected with the first clutch through an eighth rotating shaft; the input rotating shaft and the output rotating shaft are coaxially arranged.

Optionally, the output rotating shaft is connected with a seventh rotating shaft arranged on the fourth planet carrier.

Optionally, the first planet row assembly, the second planet row assembly, the third planet row assembly and the fourth planet row assembly are sequentially arranged along a direction toward the output rotating shaft.

Optionally, the multi-speed transmission comprises 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.

Optionally, the multi-stage transmission further includes a torque converter disposed in the housing, one end of the torque converter is connected to the engine, and the other end of the torque converter is connected to the input rotating shaft.

Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:

the application provides a multi-speed transmission can be applied to the car, and in multi-speed transmission use, the driver can realize the switching of eight forward gears and one reverse gear through changing the cooperation relation between five parts of shifting and four planet rows. Through the cooperation of above-mentioned component, increased partial gear fatigue factor of safety, reduced partial bearing's damage rate, and then increased multi-stage transmission's factor of safety and life, and this kind of cooperation mode has effectively reduced multi-stage transmission's internal member quantity, reduces manufacturing cost.

Drawings

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 disclosure.

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present disclosure, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

FIG. 1 is a schematic illustration of a multi-speed transmission according to one embodiment of the present invention;

FIG. 2 is a cross-sectional view of a multi-speed transmission in an embodiment of the present invention;

FIG. 3 is a schematic diagram of the shift logic for a multi-speed transmission according to one embodiment of the present invention.

Reference numerals:

p1, first planet row assembly; 10. a first sun gear; 11. a first carrier; 12. a first ring gear; p2, second planet row assembly; 20. a second sun gear; 21. a second planet carrier; 22. a second ring gear; p3, third planet row assembly; 30. a third sun gear; 31. a third carrier; 32. a third ring gear; p4, fourth planet row assembly; 40. a fourth sun gear; 41. a fourth planet carrier; 42. a fourth ring gear; 50. a housing; 51. an input shaft; 52. an output shaft; 60. a brake; 61. a first clutch; 62. a second clutch; 63. a third clutch; 64. a fourth clutch; 71. a first rotating shaft; 72. a second rotating shaft; 73. a third rotating shaft; 74. a fourth rotating shaft; 75. a fifth rotating shaft; 76. a sixth rotating shaft; 77. a seventh rotating shaft; 78. and an eighth rotating shaft.

Detailed Description

In order that the above objects, features and advantages of the present disclosure may be more clearly understood, aspects of the present disclosure will be further described below. It should be noted that the embodiments and features of the embodiments of the present disclosure may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure, but the present disclosure may be practiced in other ways than those described herein; it is to be understood that the embodiments disclosed in the specification are only a few embodiments of the present disclosure, and not all embodiments.

As shown in fig. 1, the multi-speed transmission provided by the embodiment of the present application includes a housing 50, an input rotating shaft 51, an output rotating shaft 52, a first planetary row assembly P1, a second planetary row assembly P2, a third planetary row assembly P3, a fourth planetary row assembly P4, a brake 60, a first clutch 61, a second clutch 62, a third clutch 63, and a fourth clutch 64. The brake 60 is used for connecting a 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 is used for connecting two rotating shafts in the transmission, and when the clutch is closed, the two rotating shafts connected with the clutch can synchronously rotate; when the clutch is disengaged, both rotating shafts connected to the clutch can rotate relative to the clutch.

The first planetary row assembly P1 includes a first sun gear 10, a first planetary gear, a first carrier 11, and a first ring gear 12; the second planet row assembly P2 includes a second sun gear 20, second planet gears, a second planet carrier 21 and a second ring gear 22; the third planetary row assembly P3 includes a third sun gear 30, a third planet gear, a third planet 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 planet carrier 41, and a fourth ring gear 42. The transmission process and the transmission principle of the planet row assembly are well known to those skilled in the art, and therefore, are not described in detail.

As shown in fig. 1, the input rotary shaft 51 is connected to the second clutch 62 and the second carrier 21, respectively. Specifically, the second planet carrier 21 can be rotated by the rotation of the input rotating shaft 51. When the second clutch 62 is closed, the input rotating shaft 51 can drive the other rotating shaft connected with the second clutch 62 to rotate; when the second clutch 62 is opened, the input rotary shaft 51 rotates relative to the second clutch 62.

The brake 60 is fixedly installed on an 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 the opening or closing of the stopper 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 turned on, the first rotating shaft 71 can rotate relative to the brake 60, and both the first sun gear 10 and the second sun gear 20 connected thereto can rotate.

The first carrier 11 is connected to the first clutch 61 via a second rotating shaft 72, and the first ring gear 12 is fixedly disposed on the inner wall of the housing 50. Since the first ring gear 12 is fixed to the inner wall of the housing 50, the first ring gear 12 does 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 turned on, the second sun gear 20 and the first rotating shaft 71 are rotated by the rotation of the second planet carrier 21, and then the first sun gear 10 is rotated by the first rotating shaft 71, and then the first planet carrier 11 and the second rotating shaft 72 are rotated by the first sun gear 10.

The second gear ring 22 is connected to the third sun gear 30 through a third rotating shaft 73, and the third sun gear 30 can be driven to rotate by the rotation of the second gear ring 22. One side of the third planet carrier 31 is connected to the third clutch 63 through a fourth rotating shaft 74, and the other side of the third planet carrier 31 is connected to the fourth clutch 64 through a fifth rotating shaft 75. The third ring gear 32 is connected to the second clutch 62 via the sixth rotating shaft 76, and the input rotating shaft 51 is controlled to be connected to or disconnected from the sixth rotating shaft 76 by closing or opening the second clutch 62. That is, when the second clutch 62 is closed, the input rotating shaft 51 and the sixth rotating shaft 76 rotate synchronously, and when the second clutch 62 is opened, the input rotating shaft 51 and the sixth rotating shaft 76 can rotate relatively. The fourth clutch 64 is provided on the sixth rotating shaft 76. By this design, when the fourth clutch 64 is closed, the third carrier 31 and the third ring gear 32 are connected together, so that the fourth rotating shaft 74 and the sixth rotating shaft 76 rotate at the same speed. When the fourth clutch 64 is open, the third carrier 31 and the third ring gear 32 are disengaged and the rotational speeds of the third carrier 31 and the third ring gear 32 will not be the same.

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 planet carrier 41 is connected to the third clutch 63 via a seventh rotating shaft 77, and the connection relationship between the fourth rotating shaft 74 and the seventh rotating shaft 77 can be controlled via 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 in transmission connection with the fourth planet carrier 41, and the rotation of the fourth planet carrier 41 drives the output rotating shaft 52 to rotate. Preferably, the output rotating shaft 52 is connected with the seventh rotating shaft 77 arranged on the fourth planet carrier 41, so that the equipment cost is saved, and the occupied space is reduced. Specifically, the seventh rotating shaft 77 is disposed through the fourth planet 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. Or the two ends of the fourth planet carrier 41 are both provided with seventh rotating shafts 77, the output end of one seventh rotating shaft 77 is connected with the third clutch 63, and the output end of the other seventh rotating shaft 77 is connected with the output rotating shaft 52. The fourth ring gear 42 is connected to the first clutch 61 via 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 open, the second rotating shaft 72 and the eighth rotating shaft 78 both rotate relative to the first clutch 61. The input rotating shaft 51 and the output rotating shaft 52 are coaxially arranged, so that the occupied space of the multi-stage transmission can be effectively reduced.

As shown in fig. 1 and 2, the first planetary row assembly P1, the second planetary row assembly P2, the third planetary row assembly P3 and the fourth planetary row assembly P4 are sequentially arranged in a direction toward the output rotary shaft 52, which facilitates the installation of the multi-speed transmission. Meanwhile, the arrangement of the planet row assemblies of the present application is not limited to this, and the worker can reasonably adjust the positions of the first planet row assembly P1, the second planet row assembly P2, the third planet row assembly P3 and the fourth planet row assembly P4 according to the size of the internal space of the housing 50 and the distance relationship between the mechanical components.

The multi-stage transmission provided by the application can realize three driving modes of pure electric driving, engine driving and hybrid driving. During the use of the multi-stage transmission, a driver can realize the switching of eight forward gears and one reverse gear by changing the matching relation between the five gear shifting components and the four planetary rows. Through the cooperation of above-mentioned component, increased partial gear fatigue factor of safety, reduced partial bearing's damage rate, and then increased multi-stage transmission's factor of safety and life, and this kind of cooperation mode has effectively reduced multi-stage transmission's internal member quantity, reduces manufacturing cost.

The multi-stage transmission comprises not only the planetary transmission mechanism, but also a hydraulic torque converter, a dual-mass flywheel, a hybrid module, a hydraulic system, a gear shifting unit, a hydraulic pump, an electric pump and the like. The torque converter is provided in the housing 50, and one end of the torque converter is connected to the engine and the other end is connected to the input rotating shaft 51. The mixing module is connected to the dual mass flywheel and the input end of the input shaft 51, respectively. The hydraulic system provides hydraulic pressure to the brake 60, the first clutch 61, the second clutch 62, the third clutch 63 and the fourth clutch 64 to control the opening and closing of the clutches, and additionally, provides a lubrication function. Since the above components are all relatively conventional components within a multi-speed transmission, they are not described much.

As shown in fig. 3, the multi-speed transmission includes eight forward gears and one reverse gear. The gear shifting can be realized by different matching relations of five shifting parts, four planetary rows and a plurality of rotating shafts. The specific shift operation is as follows:

a first forward gear: closing the brake 60, the first clutch 61, and the second clutch 62; the third clutch 63 and the fourth clutch 64 are released.

Since the brake 60 is closed, the first rotating shaft 71 will not rotate, so that the first planet 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, and therefore, the eighth rotating shaft 78 does not rotate. Meanwhile, since the third clutch 63 and the fourth clutch 64 are opened, power cannot be transmitted to the output rotating shaft 52 through the third carrier 31. Because the second clutch 62 is closed, power can be transmitted from the input rotating shaft 51 to the sixth rotating shaft 76, and the fourth sun gear 40 is rotated by the sixth rotating shaft 76, and the output rotating shaft 52 is rotated.

A second forward gear: closing the brake 60, the first clutch 61, and the fourth clutch 64; the second clutch 62 and the third clutch 63 are released.

Since the second clutch 62 is open, the input rotary shaft 51 cannot directly rotate the sixth rotary shaft 76. The third clutch 63 is disengaged, and therefore, the seventh rotating shaft 77 cannot be rotated by the fourth rotating shaft 74. Because the brake 60 and the first clutch 61 are engaged, the first shaft 71 and the eighth shaft 78 will not rotate, as is known from the first forward gear principle. The power of the input rotating shaft 51 is transmitted to the third rotating shaft 73 through the second planet row assembly P2, and the fourth rotating shaft 74 and the fifth rotating shaft 75 are synchronously rotated by the rotation of the third sun gear 30 because the fourth clutch 64 is closed, and the power is transmitted to the third rotating shaft 73 through the third planet row assembly P3 because the third clutch 63 is released, and then the power is transmitted to the output rotating shaft 52 through the fourth planet row assembly P4, thereby completing the power transmission.

A third forward gear: closing the first clutch 61, the second clutch 62, and the fourth clutch 64; the brake 60 and the third clutch 63 are released.

The power is input by the input rotating shaft 51, and because the brake 60 is turned off, the first rotating shaft 71 can rotate along with the second sun gear 20, and then the first rotating shaft 71 drives the first sun gear 10 to rotate, and the first sun gear 10 drives the first planet carrier 11 and the second rotating shaft 72 to rotate. Since the first clutch 61 is closed, the second rotating shaft 72 can rotate the eighth rotating shaft 78, and thus, 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 set P3 through the sixth rotating shaft 76, and the output rotating shaft 52 is rotated, thereby completing the power transmission.

A fourth forward gear: closing the first clutch 61, the third clutch 63, and the fourth clutch 64; the brake 60 and the second clutch 62 are released.

Power is input from the input rotating shaft 51, and since the brake 60 is off and the first clutch 61 is on, the power of the input rotating shaft 51 can be transmitted to the third ring gear 32, as is known from the third forward gear principle. Because the fourth clutch 64 is closed, power is transmitted to the sixth shaft 76 and thus to the third sun gear 30, which in turn rotates the output shaft 52.

A fifth forward gear: closing the first clutch 61, the second clutch 62, and the third clutch 63; the brake 60 and the fourth clutch 64 are released.

Power is input from the input rotary shaft 51, and since the brake 60 is off and the first clutch 61 is on, the power can be transmitted to the third ring gear 32. Since the second clutch 62 is closed, power can be directly transmitted to the sixth rotating shaft 76 through the input rotating shaft 51, and then to the third ring gear 32. Since the fourth clutch 64 is disengaged and the third clutch 63 is engaged, the third carrier 31 can output power to the output rotary shaft 52.

A sixth forward gear: closing the second clutch 62, the third clutch 63, and the fourth clutch 64; the brake 60 and the first clutch 61 are released.

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

A seventh forward gear: closing the brake 60, the second clutch 62, and the third clutch 63; the first clutch 61 and the fourth clutch 64 are released.

Power is input from the input rotating shaft 51, and since the brake 60 is closed and the first clutch 61 is opened, the first rotating shaft 71 does not rotate, and meanwhile, the power of the input rotating shaft 51 is transmitted to the second ring gear 22 through the second planet carrier 21, and then the power is transmitted to the third sun gear 30; since the second clutch 62 and the third clutch 63 are closed, the power of the input rotary shaft 51 can be transmitted to the third ring gear 32 via the sixth rotary shaft 76, and further, the power can be transmitted to the output rotary shaft 52 via the second carrier 21.

Eighth forward gear: closing the brake 60, the third clutch 63, and the fourth clutch 64; the first clutch 61 and the second clutch 62 are released.

Power is input from the input rotating shaft 51, and the first rotating shaft 71 does not rotate because the brake 60 is closed; power is transmitted from the second ring gear 22 of the second planetary row assembly P2 to the third planetary row assembly P3, and is transmitted to the output rotating shaft 52 through the planet carrier of the second planetary row assembly P2.

Reverse gear (R gear): closing the brake 60, the first clutch 61, and the third clutch 63; the second clutch 62 and the fourth clutch 64 are released.

Power is input from the input rotating shaft 51, and the eighth rotating shaft 78 and the first rotating shaft 71 do not rotate because the brake 60 and the first clutch 61 are closed; power is transmitted from the second ring gear 22 of the second planetary row assembly P2 to the third planetary row assembly P3, and from the third carrier 31 of the third planetary row assembly P3 to the output shaft 52.

The first sun gear 10 and the second sun gear 20 of the present application are of a left-handed design, and the third sun gear 30 and the fourth sun gear 40 are of a right-handed design. Taking the second forward gear as an example, the structure of the corresponding component is subjected to stress analysis, and the stress analysis is specifically as follows:

when the automobile 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. Referring to fig. 1 and 2, during operation of the transmission, the input rotating shaft 51 rotates and drives the second planet carrier 21 to rotate, and the second sun gear 20 is stationary, so the second planet carrier 21 drives the second ring gear 22 to rotate. The second ring gear 22 is connected with the third sun gear 30, and since the fourth clutch 64 is closed, the third planetary gearset P3 is integrated, i.e., the third sun gear 30, the third carrier 31, and the third ring gear 32 all rotate at the same speed. The third ring gear 32 rotates the fourth sun gear 40, and the brake 60 and the first clutch 61 are closed, so that the fourth ring gear 42 does not rotate, and the fourth carrier 41 is rotated by the fourth sun gear 40.

Since the second gear is the forward gear, the input rotating shaft 51 and the output rotating shaft 52 both rotate in the normal direction, which is the direction of rotation of the input rotating shaft 51 and the output rotating shaft 52 when viewed from the output end of the transmission toward the input end. Because the fourth clutch 64 is closed, the fourth planetary gearset P4 provides power transfer, and because the fourth sun gear 40 is of a right-hand design, the fourth sun gear 40 transfers axial forces to the left. As shown in fig. 2, the force direction of the fourth sun gear 40 is leftward, and thus, neither the bearing on the right side of the fourth sun gear 40 nor the bearing on the right side of the fourth carrier 41 is forced. The axial force is transmitted to the left through the fourth sun gear 40 and further through the splines and the inner hub of the corresponding clutch to the third sun gear 30, so that the third sun gear 30 receives a leftward force, wherein bearings are provided between adjacent splines and the inner hub. On the other hand, the input rotating shaft 51 drives the second planet carrier 21 to rotate, and since the second sun gear 20 adopts a left-handed design, the axial force applied to the second sun gear 20 is rightward, and as is well known, in the planet row, the directions of the axial forces applied to the sun gear and the ring gear are opposite, the axial force applied to the planet carrier is offset, and therefore, the force applied to the second ring gear 22 is leftward. The third sun gear 30 is connected to the second ring gear 22, so that the axial force applied to the third sun gear 30 is directed to the left, and the axial force applied to the third ring gear 32 is directed to the right. The third ring gear 32 is connected to the fourth sun gear 40, so that the axial force applied by the third ring gear 32 to the fourth sun gear 40 is applied to the right, and then the left axial force of the fourth sun gear 40 is offset, so that the stress of each bearing between the third sun gear 30 and the fourth sun gear 40 is reduced.

That is, during operation of the transmission, power flows through the third planetary gearset P3 and causes the third planetary gearset P3 to generate a force that balances the output of the fourth sun gear 40, thereby causing a reduction in bearing forces between the third planetary gearset P3 and the fourth planetary gearset P4. Moreover, the bearing near the output rotating shaft 52 of the transmission is stressed greatly in the whole transmission, so that the stress of the part of the bearing can be effectively reduced by the design mode, and further the damage rate of the bearing is reduced.

Where both the left and right directions are directions relative to fig. 3, specifically, the left direction is toward the input end of the transmission, and the right direction is toward the output end of the transmission. In the existing transmission, the axial directions of the rotating parts are connected through bearings, so that two adjacent rotating parts can rotate relatively, and axial support and axial force transmission can be provided. This type of connection is common knowledge to those skilled in the art and therefore the location of the bearings of the present disclosure will be readily apparent to those skilled in the art and therefore not overly described.

It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The foregoing are merely exemplary embodiments of the present disclosure, which enable those skilled in the art to understand or practice the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (5)

1. A multi-stage transmission is characterized by comprising a shell, an input rotating shaft, an output rotating shaft, a first planet row assembly, a second planet row assembly, a third planet row assembly, a fourth planet row assembly, a brake, a first clutch, a second clutch, a third clutch and a fourth clutch;

the first planet carrier assembly comprises a first sun gear, a first planet carrier and a first ring gear; the second planet row assembly comprises a second sun gear, a second planet carrier and a second gear ring; the third planet bar assembly includes a third sun gear, a third planet carrier, and a third ring gear; the fourth planet row assembly comprises a fourth sun gear, a fourth planet carrier and a fourth gear ring;

the input rotating shaft is respectively connected with the second clutch and the second planet carrier;

the brake is fixedly arranged on the inner wall of the shell and is connected with the first sun gear and the second sun gear through a first rotating shaft;

the first planet carrier is connected with the first clutch through a second rotating shaft, and the first gear ring is fixedly arranged on the inner wall of the shell;

the second gear ring is connected with the third sun gear through a third rotating shaft; one side of the third planet carrier is connected with the third clutch through a fourth rotating shaft, and the other side of the third planet carrier is connected with the fourth clutch through a fifth rotating shaft; the third gear ring is connected with the second clutch through a sixth rotating shaft; the fourth clutch is arranged on the sixth rotating shaft;

the fourth sun gear is connected with the sixth rotating shaft, the fourth planet carrier is connected with the third clutch through a seventh rotating shaft, and the output rotating shaft is in transmission connection with the fourth planet carrier; the fourth gear ring is connected with the first clutch through an eighth rotating shaft; the input rotating shaft and the output rotating shaft are coaxially arranged.

2. The variable transmission of claim 1, wherein the output shaft is drivingly connected to a seventh shaft disposed on the fourth carrier.

3. The multi-speed transmission of claim 1, wherein the first, second, third and fourth planet bar assemblies are arranged in sequence in a direction toward the output shaft.

4. The multi-speed transmission of claim 1, comprising 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 of claim 1, further comprising a torque converter disposed within said housing, said torque converter connected at one end to an engine and at another end to said input shaft.

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