Double-planet-row power holding type four-gear automatic transmission

Abstract

The invention discloses a double-planet-row power holding type four-gear automatic transmission, which relates to the technical field of automobile automatic transmissions and is characterized in that a first planet row is in transmission connection with a motor of an electric vehicle through a first input shaft, and a first clutch is arranged between the first input shaft and a first planet gear; a first brake is arranged between the first gear ring and the transmission shell; one end of the second input shaft is connected with the first planet carrier, and the other end of the second input shaft is provided with a second planet row; a second clutch is arranged between the second input shaft and the second planet carrier, and a second brake is arranged between the second gear ring and the transmission shell; the second planet carrier is in transmission connection with the intermediate shaft through a gear; the intermediate shaft is in transmission connection with a differential through a main reducer, and the differential is in transmission connection with driving wheels of the electric vehicle through half shafts. The electric vehicle can run at four gears, the running efficiency of the motor is improved, and power uninterrupted gear shifting of the electric vehicle is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of automobile automatic transmissions, in particular to a double planetary gear power-holding type four-speed automatic transmission. Background Art

[0002] The rapid development of the automobile industry has brought convenience to people's lives, but it has also brought about environmental and energy crises. Especially in my country, the prevention and control of air pollution in large cities is imminent, and one of the main sources of pollution is automobile emissions. The electrification of automobiles is expected to alleviate or partially solve these problems.

[0003] Since the motor has a large speed regulation range and has the characteristics of constant torque at low speed and constant power at high speed, in theory, the motor can achieve stepless speed regulation without the need for a transmission. Therefore, in terms of power transmission, electric vehicles often cancel the transmission and use a fixed speed ratio. But in fact, there are many shortcomings in driving vehicles in this way: first, the motor speed regulation range is difficult to take into account both high torque and maximum speed; second, when the wheels are directly driven, the motor operating point is often in a low efficiency area, which not only wastes electric energy, but also increases the requirements for the motor, resulting in poor vehicle driving economy and limited cruising range. Therefore, in order to improve the efficiency of the motor during operation and reduce the requirements of electric vehicles for motors and batteries, it is necessary to add a multi-speed ratio transmission to the electric vehicle.

[0004] At present, some electric vehicles in China are equipped with transmissions, but the basic structure is still a traditional parallel shaft automatic transmission. This type of transmission is often large in size. At the same time, due to the presence of synchronizers, it is impossible to overcome power interruption when shifting gears, and the comfort of use is poor. In theory, two planetary gear trains can also be used to form a multi-speed transmission, but the structure is complex, the transmission efficiency is low, and the processing precision requirements are high. The current commercialized electric vehicle transmission usually only has two gears, which are used for low-speed starting and high-speed cruising of electric vehicles respectively. However, when driving on urban roads and in the wild, it is often necessary to drive at different medium speeds. Simply driving in high gear or low gear will reduce the efficiency of the motor. Summary of the invention

[0005] The purpose of the present invention is to provide a dual planetary gear power-holding four-speed automatic transmission in order to solve at least one of the above technical problems.

[0006] The embodiment of the present invention provides a dual planetary gear power retention type four-speed automatic transmission, comprising: a first input shaft, a second input shaft, a first planetary gear, a second planetary gear, an intermediate shaft, a final reducer and a differential; wherein the first planetary gear, the second planetary gear, the intermediate shaft, the final reducer and the differential are all arranged in a transmission case; the first planetary gear comprises a first planetary gear, a first ring gear and a first planet carrier, and the second planetary gear comprises a second planet carrier and a second ring gear; the first planetary gear is connected to the electric motor of the electric vehicle through the first input shaft, a first clutch is arranged between the first input shaft and the first planetary gear, and a first brake is arranged between the first ring gear and the transmission case; one end of the second input shaft is connected to the first planet carrier, and the other end of the second input shaft is installed with the second planetary gear; a second clutch is arranged between the second input shaft and the second planet carrier, and a second brake is arranged between the second ring gear and the transmission case; the second planet carrier is connected to the intermediate shaft through gear transmission; the intermediate shaft is connected to the differential through the final reducer, and the differential is connected to the driving wheel of the electric vehicle through a half shaft.

[0007] Furthermore, the first planetary gear also includes a first sun gear, and the number of the first planetary gears is multiple; the first sun gear is fixedly connected to one end of the first input shaft extending into the transmission case, and the multiple first planetary gears are evenly distributed around the first sun gear, the first planet carrier is fixedly connected to the first planetary gears, the first ring gear is installed on the rotating part of the first brake, the housing of the first brake is fixed on the inner wall of the transmission case, the first planetary gear is meshed with the outside of the first sun gear, and the first planetary gear is meshed with the inside of the first ring gear.

[0008] Furthermore, the second planetary gear also includes a second sun gear and a plurality of second planetary gears; the second sun gear is fixedly connected to the second input shaft, the plurality of second planetary gears are evenly distributed around the second sun gear, the second planet carrier is fixedly connected to the second planetary gears, the second ring gear is installed on the rotating part of the second brake, the housing of the second brake is fixed on the inner wall of the transmission case, the second planetary gears are externally meshed with the second sun gear, and the second planetary gears are internally meshed with the second ring gear, and the second planet carrier is mounted on the second input shaft.

[0009] Further, one end of the first clutch is relatively fixed to the first input shaft, and the other end of the first clutch is relatively fixed to the first planet carrier; one end of the second clutch is relatively fixed to the second input shaft, and the other end of the second clutch is relatively fixed to the second planet carrier.

[0010] Furthermore, a guide driving gear is fixedly connected to the second planet carrier, and the guide driving gear is sleeved on the second input shaft; a guide driven gear is installed on the intermediate shaft, and the guide driving gear is constantly meshed with the guide driven gear.

[0011] Furthermore, the main reducer includes a main reducer driving gear and a main reducer driven gear; wherein the main reducer driving gear is fixedly connected to the intermediate shaft, the main reducer driven gear is fixedly connected to the differential, and the main reducer driving gear is constantly meshed with the main reducer driven gear.

[0012] Furthermore, the half shaft comprises a left half shaft and a right half shaft; and both ends of the differential are respectively mounted on the left half shaft and the right half shaft.

[0013] Further, the first clutch and the second clutch include electromagnetic clutches or mechanical clutches.

[0014] Further, the first brake and the second brake include electromagnetic brakes or mechanical brakes.

[0015] Furthermore, the intermediate shaft and the half shafts are respectively mounted on the transmission housing through bearings.

[0016] The present invention provides a double planetary gear power-holding four-speed automatic transmission, which adopts a double-row planetary gear system as a speed change mechanism, switches gears through the sliding friction of two clutches and two brakes, has no power interruption, and can significantly improve the smoothness of gear shifting; realizes four-speed shifting, can effectively improve the efficiency of the motor, and alleviates the technical problems of low motor efficiency and poor comfort caused by the inability to overcome power interruption during gear shifting due to the presence of a synchronizer in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic diagram of the structure of a dual planetary gear power-holding four-speed automatic transmission provided by an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of a power transmission route of a dual planetary gear power-holding four-speed automatic transmission in first gear provided by an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the power transmission route of a dual planetary gear power-holding four-speed automatic transmission in second gear provided by an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of a power transmission route of a dual planetary gear power-holding type four-speed automatic transmission in third gear provided by an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of the power transmission route of a dual planetary gear power-holding four-speed automatic transmission in fourth gear provided by an embodiment of the present invention.

[0023] In the figure: 1, first input shaft, 2, first clutch, 3, first brake, 4, first planetary gear, 5, first ring gear, 6, first planetary carrier, 7, first sun gear, 8, second brake, 9, second ring gear, 10, second planetary gear, 11, second clutch, 12, second planetary carrier, 13, guide driving gear, 14, second input shaft, 15, transmission case, 16, second sun gear, 17, guide driven gear, 18, right half shaft, 19, bearing, 20, main reducer driving gear, 21, main reducer driven gear, 22, differential, 23, left half shaft, 24, intermediate shaft, 25, motor. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Figure 1 1 is a schematic diagram of a dual planetary gear power-holding four-speed automatic transmission according to an embodiment of the present invention. Figure 1 As shown, the transmission includes: a first input shaft 1, a second input shaft 14, a first planetary gear, a second planetary gear, an intermediate shaft 24, a final reducer and a differential 22. The first planetary gear, the second planetary gear, the intermediate shaft 24, the final reducer and the differential 22 are all arranged in a transmission case 15; the first planetary gear includes a first planetary gear 4, a first ring gear 5 and a first planet carrier 6, and the second planetary gear includes a second planet carrier 12 and a second ring gear 9.

[0026] Specifically, Figure 1As shown, the first planetary gear is connected to the electric motor 25 of the electric vehicle through the first input shaft 1 , a first clutch 2 is arranged between the first input shaft 1 and the first planetary gear 4 , and a first brake 3 is arranged between the first ring gear 5 and the transmission housing 15 .

[0027] One end of the second input shaft 14 is connected to the first planetary carrier 6 , and the other end of the second input shaft 14 is installed with the second planetary gear; a second clutch 11 is arranged between the second input shaft 14 and the second planetary carrier 12 , and a second brake 8 is arranged between the second ring gear 9 and the transmission case 15 .

[0028] The second planet carrier 12 is connected to the intermediate shaft 24 through gear transmission; the intermediate shaft 24 is connected to the differential 22 through the main reducer, and the differential 22 is connected to the driving wheels of the electric vehicle through the half shafts.

[0029] Specifically, Figure 1 As shown, the first planetary row also includes a first sun gear 7, and the number of first planetary gears 4 is multiple; the first sun gear 7 is fixedly connected to one end of the first input shaft 1 extending into the transmission case 15, and multiple first planetary gears 4 are evenly distributed around the first sun gear 7, the first planetary carrier 6 is fixedly connected to the first planetary gears 4, the first ring gear 5 is installed on the rotating part of the first brake 3, the housing of the first brake 3 is fixed on the inner wall of the transmission case 15, the first planetary gear 4 is externally meshed with the first sun gear 7, and the first planetary gear 4 is internally meshed with the first ring gear 5.

[0030] Specifically, Figure 1 As shown, the second planetary gear row also includes a second sun gear 16 and a plurality of second planetary gears 10; the second sun gear 16 is fixedly connected to the second input shaft 14, a plurality of second planetary gears 10 are evenly distributed around the second sun gear 16, the second planetary carrier 12 is fixedly connected to the second planetary gears 10, the second ring gear 9 is installed on the rotating part of the second brake 8, the housing of the second brake 8 is fixed on the inner wall of the transmission case 15, the second planetary gears 10 are externally meshed with the second sun gear 16, and the second planetary gears 10 are internally meshed with the second ring gear 9, and the second planetary carrier 12 is mounted on the second input shaft 14.

[0031] Specifically, Figure 1 As shown, one end of the first clutch 2 is relatively fixed to the first input shaft 1, and the other end of the first clutch 2 is relatively fixed to the first planet carrier 6;

[0032] One end of the second clutch 11 is relatively fixed to the second input shaft 14 , and the other end of the second clutch 11 is relatively fixed to the second planet carrier 12 .

[0033] Specifically, Figure 1As shown, the second planet carrier 12 is fixedly connected to the guide driving gear 13, and the guide driving gear 13 is sleeved on the second input shaft 14; the intermediate shaft 24 is mounted with the guide driven gear 17, and the guide driving gear 13 is constantly meshed with the guide driven gear 17.

[0034] The main reducer includes a main reducer driving gear 20 and a main reducer driven gear 21; wherein the main reducer driving gear 20 is fixedly connected to the intermediate shaft 24, the main reducer driven gear 21 is fixedly connected to the differential 22, and the main reducer driving gear 20 and the main reducer driven gear 21 are constantly meshed. In the embodiment of the present invention, the rotation of the intermediate shaft 24 is transmitted to the differential 22 through the meshing of the main reducer driving gear 20 and the main reducer driven gear 21.

[0035] Specifically, Figure 1 As shown, the half shafts include a left half shaft 23 and a right half shaft 18; both ends of the differential 22 are mounted on the left half shaft 23 and the right half shaft 18 respectively.

[0036] Preferably, if Figure 1 As shown, the intermediate shaft 24 and the half shafts are respectively mounted on the transmission case 15 via bearings 19 .

[0037] The double planetary gear power-holding four-speed automatic transmission provided in the embodiment of the present invention has the following characteristics: when the first clutch 2 is engaged, the first sun gear 7 and the first planet carrier 6 are interconnected; when the second clutch 11 is engaged, the second sun gear 16 and the second planet carrier 12 are interconnected; when the first brake 3 is engaged, the first ring gear 5 and the transmission case 15 are interconnected; when the second brake 8 is engaged, the second ring gear 9 and the transmission case 15 are interconnected.

[0038] Optionally, in the embodiment of the present invention, the first clutch 2 and the second clutch 11 include electromagnetic clutches or mechanical clutches.

[0039] For example, the first clutch 2 may be an electromagnetic clutch or a mechanical clutch.

[0040] For example, the second clutch 11 may be an electromagnetic clutch or a mechanical clutch.

[0041] Optionally, in the embodiment of the present invention, the first brake 3 and the second brake 8 include electromagnetic brakes or mechanical brakes.

[0042] For example, the first brake 3 may be an electromagnetic brake or a mechanical brake.

[0043] For example, the second brake 8 may be an electromagnetic brake or a mechanical brake.

[0044] The working principle and working process of the dual planetary gear power-holding four-speed automatic transmission proposed by the present invention are described in detail below in conjunction with the accompanying drawings. Assume that the characteristic parameter of the gear system of the first planetary gear is k1 (i.e., the gear ratio of the first ring gear 5 to the first sun gear 7), the characteristic parameter of the gear system of the second planetary gear is k2 (i.e., the gear ratio of the second ring gear 9 to the second sun gear 16), and k2>k1.

[0045] Figure 2 The figure is a schematic diagram of the power transmission route of a dual planetary gear power-holding four-speed automatic transmission in the first gear according to an embodiment of the present invention. The first gear of the automatic transmission is used for starting, climbing, low-speed driving and reversing of the car. Figure 2 As shown, when the automatic transmission is in the first gear, the first clutch 2 and the second clutch 11 are both disconnected, the first brake 3 and the second brake 8 are both engaged, and the power of the motor 25 is transmitted to the first sun gear 7 of the first planetary row through the first input shaft 1. At this time, since the first ring gear 5 is fixed on the transmission case 15, a speed ratio k1+1 greater than 1 is generated between the first sun gear 7 of the first planetary row and the first planetary carrier 6 through the first planetary gear 4, and the power is transmitted to the second sun gear 16 through the first planetary gear 4 and the first planetary carrier 6; since the second ring gear 9 is fixed on the transmission case 15, a speed ratio k2+1 greater than 1 is generated between the second sun gear 16 of the second planetary row and the second planetary carrier 12 through the second planetary gear 10, and the power is transmitted to the guide driving gear 13 through the second planetary gear 10 and the second planetary carrier 12, and then transmitted to the left half shaft 23 and the right half shaft 18 through the guide driven gear 17, the intermediate shaft 24, the main reducer driving gear 20, the main reducer driven gear 21, and the differential 22, thereby driving the wheels. First gear transmission ratio = (k1+1)×(k2+1).

[0046] Figure 3 The figure is a schematic diagram of the power transmission route of a dual planetary gear power retention type four-speed automatic transmission in the second gear according to an embodiment of the present invention. The second gear of the automatic transmission is used for medium-speed driving when the vehicle is off-road. Figure 3As shown, when the automatic transmission is in the second gear, the first brake 3 and the second clutch 11 are both disconnected, the first clutch 2 and the second brake 8 are both engaged, and the power of the motor 25 is transmitted to the first sun gear 7 of the first planetary row through the first input shaft 1. At this time, since the first sun gear 7 is interconnected with the first planetary carrier 6, the first planetary row rotates as a whole, and the speed ratio between the first sun gear 7 and the first planetary carrier 6 is 1. The power is transmitted to the second sun gear 16 of the second planetary row through the first planetary gear 4 and the first planetary carrier 6; since the second ring gear 9 is fixed on the transmission case 15, a speed ratio k2+1 greater than 1 is generated between the second sun gear 16 of the second planetary row and the second planetary carrier 12 through the second planetary gear 10, and the power is transmitted to the guide driving gear 13 through the second planetary gear 10 and the second planetary carrier 12, and then transmitted to the left half shaft 23 and the right half shaft 18 through the guide driven gear 17, the intermediate shaft 24, the main reducer driving gear 20, the main reducer driven gear 21, and the differential 22, thereby driving the wheels. Second gear transmission ratio = 1×(k2+1) = k2+1.

[0047] Figure 4 The figure is a schematic diagram of the power transmission route of a dual planetary gear power retention type four-speed automatic transmission in the third gear according to an embodiment of the present invention. The third gear of the automatic transmission is used for medium-speed driving of a car in urban road conditions. Figure 4 As shown, when the automatic transmission is in the third gear, the first clutch 2 and the second brake 8 are both disconnected, the first brake 3 and the second clutch 11 are both engaged, and the power of the motor 25 is transmitted to the first sun gear 7 of the first planetary row through the first input shaft 1. At this time, since the first ring gear 5 is fixed on the transmission case 15, a speed ratio k1+1 greater than 1 is generated between the first sun gear 7 of the first planetary row and the first planetary carrier 6 through the first planetary gear 4, and the power is transmitted to the second sun gear 16 through the first planetary gear 4 and the first planetary carrier 6; since the second sun gear 16 is interconnected with the second planetary carrier 12, the second planetary row rotates as a whole, and the speed ratio between the second sun gear 16 and the second planetary carrier 12 is 1, and the power is transmitted to the guide driving gear 13 through the second planetary gear 10 and the second planetary carrier 12, and then transmitted to the left half shaft 23 and the right half shaft 18 through the guide driven gear 17, the intermediate shaft 24, the main reducer driving gear 20, the main reducer driven gear 21, and the differential 22, thereby driving the wheels. The third gear transmission ratio = (k1+1)×1 = k1+1.

[0048] Figure 5The present invention is a schematic diagram of a power transmission route of a dual planetary gear power-holding four-speed automatic transmission in the fourth gear according to an embodiment of the present invention. The fourth gear of the automatic transmission is used for high-speed driving of a car. When the transmission is in the fourth gear, the first brake 3 and the second brake 8 are both disconnected, the first clutch 2 and the second clutch 11 are both engaged, and the power of the motor 25 is transmitted to the first sun gear 7 of the first planetary row through the first input shaft 1. At this time, since the first sun gear 7 is interconnected with the first planetary carrier 6, the first planetary row rotates as a whole, and the speed ratio between the first sun gear 7 and the first planetary carrier 6 is 1. The power is transmitted to the second sun gear 16 of the second planetary row through the first planetary gear 4 and the first planetary carrier 6; since the second sun gear 16 is interconnected with the second planetary carrier 12, the second planetary row rotates as a whole, and the speed ratio between the second sun gear 16 and the second planetary carrier 12 is 1. The power is transmitted to the guide driving gear 13 through the second planetary gear 10 and the second planetary carrier 12, and then transmitted to the left half shaft 23 and the right half shaft 18 through the guide driven gear 17, the intermediate shaft 24, the main reducer driving gear 20, the main reducer driven gear 21, and the differential 22, thereby driving the wheels. The fourth gear transmission ratio = 1×1 = 1.

[0049] When the first brake 3, the second brake 8, the first clutch 2, and the second clutch 11 are all disconnected, the transmission is in neutral, which can meet the needs of towing or repairing the electric vehicle.

[0050] When the transmission switches from the first gear to the second gear, the first brake 3 is gradually disengaged, and at the same time the first clutch 2 is gradually engaged, the second brake 8 remains engaged, and the second clutch 11 remains disengaged, so that the first ring gear 5 is gradually disconnected from the transmission case 15, and the first sun gear 7 is gradually engaged with the first planetary carrier 6. When the first sun gear 7 is fully engaged with the first planetary carrier 6, the switch from the first gear to the second gear is completed.

[0051] When the transmission switches from the second gear to the first gear, the first clutch 2 is gradually disconnected, and at the same time the first brake 3 is gradually engaged, the second brake 8 remains engaged, and the second clutch 11 remains disconnected, so that the first sun gear 7 and the first planetary carrier 6 are gradually disconnected, and the first ring gear 5 and the transmission case 15 are gradually engaged. When the first ring gear 5 and the transmission case 15 are fully engaged, the switch from the second gear to the first gear is completed.

[0052] When the transmission switches from the second gear to the third gear, the first clutch 2 and the second brake 8 are gradually disconnected, and at the same time, the first brake 3 and the second clutch 11 are gradually engaged, so that the first sun gear 7 and the first planetary carrier 6, the second ring gear 9 and the transmission case 15 are gradually disconnected, and the first ring gear 5 and the transmission case 15, and the second sun gear 16 and the second planetary carrier 12 are gradually engaged. When the first ring gear 5 and the transmission case 15, and the second sun gear 16 and the second planetary carrier 12 are fully engaged, the switch from the second gear to the third gear is completed.

[0053] When the transmission switches from the third gear to the second gear, the first brake 3 and the second clutch 11 are gradually disconnected, and at the same time, the first clutch 2 and the second brake 8 are gradually engaged, so that the first ring gear 5 and the transmission case 15, the second sun gear 16 and the second planetary carrier 12 are gradually disconnected, and the first sun gear 7 and the first planetary carrier 6, and the second ring gear 9 and the transmission case 15 are gradually engaged. When the first sun gear 7 and the first planetary carrier 6, and the second ring gear 9 and the transmission case 15 are fully engaged, the switch from the third gear to the second gear is completed.

[0054] When the transmission switches from the third gear to the fourth gear, the first brake 3 is gradually disconnected, and at the same time the first clutch 2 is gradually engaged, the second clutch 11 remains engaged, and the second brake 8 remains disconnected, so that the first ring gear 5 is gradually disconnected from the transmission case 15, and the first sun gear 7 is gradually engaged with the first planetary carrier 6. When the first sun gear 7 is fully engaged with the first planetary carrier 6, the switch from the third gear to the fourth gear is completed.

[0055] When the transmission switches from the fourth gear to the third gear, the first clutch 2 is gradually disconnected and the first brake 3 is gradually engaged. The second clutch 11 remains engaged and the second brake 8 remains disconnected, so that the first sun gear 7 is gradually disconnected from the first planetary carrier 6 and the first ring gear 5 is gradually engaged with the transmission case 15. When the first ring gear 5 is fully engaged with the transmission case 15, the switch from the fourth gear to the third gear is completed.

[0056] When the transmission switches from the first gear to the third gear, the second brake 8 is gradually disengaged, and at the same time the second clutch 11 is gradually engaged, the first brake 3 remains engaged, and the first clutch 2 remains disengaged, so that the second ring gear 9 is gradually disconnected from the transmission case 15, and the second sun gear 16 is gradually engaged with the second planetary carrier 12. When the second sun gear 16 is fully engaged with the second planetary carrier 12, the switch from the first gear to the third gear is completed.

[0057] When the transmission switches from the third gear to the first gear, the second clutch 11 is gradually disconnected, and at the same time the second brake 8 is gradually engaged, the first brake 3 remains engaged, and the first clutch 2 remains disconnected, so that the second sun gear 16 and the second planetary carrier 12 are gradually disconnected, and the second ring gear 9 and the transmission case 15 are gradually engaged. When the second ring gear 9 and the transmission case 15 are fully engaged, the switch from the third gear to the first gear is completed.

[0058] When the transmission switches from the first gear to the fourth gear, the first brake 3 and the second brake 8 are gradually disconnected, and at the same time, the first clutch 2 and the second clutch 11 are gradually engaged, so that the first ring gear 5 and the transmission case 15, the second ring gear 9 and the transmission case 15 are gradually disconnected, and the first sun gear 7 and the first planetary carrier 6, and the second sun gear 16 and the second planetary carrier 12 are gradually engaged. When the first sun gear 7 and the first planetary carrier 6, and the second sun gear 16 and the second planetary carrier 12 are fully engaged, the switch from the first gear to the fourth gear is completed.

[0059] When the transmission switches from the fourth gear to the first gear, the first clutch 2 and the second clutch 11 are gradually disconnected, and at the same time, the first brake 3 and the second brake 8 are gradually engaged, so that the first sun gear 7 and the first planetary carrier 6, the second sun gear 16 and the second planetary carrier 12 are gradually disconnected, and the first ring gear 5 and the transmission case 15, and the second ring gear 9 and the transmission case 15 are gradually engaged. When the first ring gear 5 and the transmission case 15, and the second ring gear 9 and the transmission case 15 are fully engaged, the switch from the fourth gear to the first gear is completed.

[0060] When the transmission switches from the second gear to the fourth gear, the second brake 8 is gradually disengaged, and at the same time the second clutch 11 is gradually engaged, the first clutch 2 remains engaged, and the first brake 3 remains disengaged, so that the second ring gear 9 is gradually disconnected from the transmission case 15, and the second sun gear 16 is gradually engaged with the second planetary carrier 12. When the second sun gear 16 is fully engaged with the second planetary carrier 12, the switch from the second gear to the fourth gear is completed.

[0061] When the transmission switches from the fourth gear to the second gear, the second clutch 11 is gradually disconnected and the second brake 8 is gradually engaged. The first clutch 2 remains engaged and the first brake 3 remains disconnected, so that the second sun gear 16 is gradually disconnected from the second planetary carrier 12 and the second ring gear 9 is gradually engaged with the transmission case 15. When the second ring gear 9 is fully engaged with the transmission case 15, the switch from the fourth gear to the second gear is completed.

[0062] From the above description, it can be seen that an embodiment of the present invention provides a double planetary gear power-holding four-speed automatic transmission, which adopts a double-row planetary gear system as a speed change mechanism to achieve four-speed shifting. The transmission has a small outer size, has the advantage of being lightweight, and is convenient for vehicle layout. The gear shifting is performed through the sliding friction of two clutches and two brakes without power interruption, which can significantly improve the smoothness of gear shifting. The four-speed shifting can meet the requirements of different vehicle speeds in urban and off-road conditions, and effectively improve the efficiency of the motor.

[0063] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0064] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A dual planetary gear power-holding four-speed automatic transmission, characterized in that: include: A first input shaft, a second input shaft, a first planetary gear, a second planetary gear, an intermediate shaft, a final reducer and a differential; wherein the first planetary gear, the second planetary gear, the intermediate shaft, the final reducer and the differential are all arranged in a transmission case; the first planetary gear comprises a first planetary gear, a first ring gear and a first planet carrier, and the second planetary gear comprises a second planet carrier and a second ring gear; The first planetary gear is connected to the electric motor of the electric vehicle through the first input shaft, a first clutch is arranged between the first input shaft and the first planetary gear, and a first brake is arranged between the first ring gear and the transmission housing; One end of the second input shaft is connected to the first planet carrier, and the other end of the second input shaft is mounted with the second planetary gear; a second clutch is arranged between the second input shaft and the second planet carrier, and a second brake is arranged between the second ring gear and the transmission housing; The second planet carrier is connected to the intermediate shaft via gear transmission; the intermediate shaft is connected to the differential via the main reducer, and the differential is connected to the driving wheels of the electric vehicle via a half shaft.

2. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: The first planetary gear also includes a first sun gear, and the number of the first planetary gears is multiple; the first sun gear is fixedly connected to one end of the first input shaft extending into the transmission case, and the multiple first planetary gears are evenly distributed around the first sun gear, the first planet carrier is fixedly connected to the first planetary gears, the first ring gear is installed on the rotating part of the first brake, the housing of the first brake is fixed on the inner wall of the transmission case, the first planetary gear is meshed with the outside of the first sun gear, and the first planetary gear is meshed with the inside of the first ring gear.

3. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: The second planetary gear also includes a second sun gear and a plurality of second planetary gears; the second sun gear is fixedly connected to the second input shaft, and the plurality of second planetary gears are evenly distributed around the second sun gear; the second planet carrier is fixedly connected to the second planetary gears, and the second ring gear is installed on the rotating part of the second brake; the housing of the second brake is fixed to the inner wall of the transmission case; the second planetary gears are externally meshed with the second sun gear, and the second planetary gears are internally meshed with the second ring gear; and the second planet carrier is mounted on the second input shaft.

4. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: One end of the first clutch is relatively fixed to the first input shaft, and the other end of the first clutch is relatively fixed to the first planet carrier; One end of the second clutch is fixed relatively to the second input shaft, and the other end of the second clutch is fixed relatively to the second planet carrier.

5. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: The second planet carrier is fixedly connected with a guide driving gear, and the guide driving gear is sleeved on the second input shaft; the intermediate shaft is equipped with a guide driven gear, and the guide driving gear is constantly meshed with the guide driven gear.

6. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: The main reducer comprises a main reducer driving gear and a main reducer driven gear; wherein the main reducer driving gear is fixedly connected to the intermediate shaft, the main reducer driven gear is fixedly connected to the differential, and the main reducer driving gear is constantly meshed with the main reducer driven gear.

7. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: The half shafts include a left half shaft and a right half shaft; and the two ends of the differential are respectively mounted on the left half shaft and the right half shaft.

8. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: The first clutch and the second clutch include electromagnetic clutches or mechanical clutches.

9. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: The first brake and the second brake include electromagnetic brakes or mechanical brakes.

10. The dual planetary gear power holding type four-speed automatic transmission according to claim 1, characterized in that: The intermediate shaft and the half shafts are respectively mounted on the transmission case through bearings.

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