阅读说明：本技术 一种匹配新能源纯电动汽车的自动换挡两挡减速器 (Automatic gear shifting two-gear speed reducer matched with new energy pure electric automobile ) 是由 赵宇 全玉辉 郝文源 张洪炎 张玉波 于 2021-08-04 设计创作，主要内容包括：本发明公开了一种匹配新能源纯电动汽车的自动换挡两挡减速器,包括输入轴总成、中间轴总成、同步器总成、换挡机构总成、差速器总成,输入轴总成包括输入轴,输入轴上分别设有1挡主动齿轮及2挡主动齿轮,中间轴总成包括中间轴,中间轴上转动连接有1挡从动齿轮及2挡从动齿轮,1挡从动齿轮与1挡主动齿轮啮合传动,2挡从动齿轮与2挡主动齿轮啮合传动；中间轴前段设有主减速器主动齿轮；所述同步器总成固定在中间轴上,换挡机构总成装配在同步器总成上,用于控制同步器总成与1挡从动齿轮或2挡从动齿轮接合实现挡位选择；差速器总成通过主减速器从动齿轮与中间轴总成的主减速器主动齿轮啮合传动,并将动力从差速器半轴输出。(The invention discloses an automatic gear shifting two-gear speed reducer matched with a new energy pure electric vehicle, which comprises an input shaft assembly, an intermediate shaft assembly, a synchronizer assembly, a gear shifting mechanism assembly and a differential mechanism assembly, wherein the input shaft assembly comprises an input shaft, a 1-gear driving gear and a 2-gear driving gear are respectively arranged on the input shaft, the intermediate shaft assembly comprises an intermediate shaft, the intermediate shaft is rotatably connected with a 1-gear driven gear and a 2-gear driven gear, the 1-gear driven gear is in meshing transmission with the 1-gear driving gear, and the 2-gear driven gear is in meshing transmission with the 2-gear driving gear; the front section of the intermediate shaft is provided with a driving gear of a main speed reducer; the synchronizer assembly is fixed on the intermediate shaft, and the gear shifting mechanism assembly is assembled on the synchronizer assembly and is used for controlling the synchronizer assembly to be connected with the 1-gear driven gear or the 2-gear driven gear to realize gear selection; the differential assembly is in meshed transmission with a driving gear of a main speed reducer of the intermediate shaft assembly through a driven gear of the main speed reducer, and power is output from a differential half shaft.)

1. An automatic gear shifting two-gear speed reducer matched with a new energy pure electric vehicle is characterized by comprising a front shell (1), a rear shell (2), an input shaft assembly (3), an intermediate shaft assembly (4), a synchronizer assembly (5), a gear shifting mechanism assembly (6) and a differential mechanism assembly (7); the input shaft assembly (3) comprises an input shaft (31), the input shaft (31) is connected with a driving motor of the whole vehicle, and a 1-gear driving gear (32) and a 2-gear driving gear (33) are respectively arranged on the input shaft (31); the intermediate shaft assembly (4) comprises an intermediate shaft (41), the intermediate shaft (41) is respectively and rotatably connected with a 1-gear driven gear (43) and a 2-gear driven gear (44), the 1-gear driven gear (43) is in meshing transmission with the 1-gear driving gear (32), and the 2-gear driven gear (44) is in meshing transmission with the 2-gear driving gear (33); a main reducer driving gear (42) is arranged at the front section of the intermediate shaft (41); the synchronizer assembly (5) is fixed on the intermediate shaft and is positioned between the 1-gear driven gear (43) and the 2-gear driven gear (44); a shifting fork of the gear shifting mechanism assembly (6) is assembled on a synchronizer gear sleeve of the synchronizer assembly (5) and is used for controlling the synchronizer assembly (5) to be engaged with the 1-gear driven gear (43) or the 2-gear driven gear (44) to realize gear selection; the differential assembly (7) is in meshed transmission with a main reducer driving gear (42) of the intermediate shaft assembly (4) through a main reducer driven gear (71), and power is output from a differential half shaft (75).

2. The automatic gear shifting two-gear speed reducer matched with the new-energy pure electric vehicle is characterized in that the gear shifting mechanism assembly (6) comprises a gear shifting driving motor (61), a ball screw (62), a gear shifting block (63), a gear shifting fork shaft (64) and a gear shifting fork (65); ball (62) and the output shaft of driving motor (61) of shifting, shift block (63) of shifting are connected with ball (62) and along ball (62) axial motion, shift fork axle (64) and shift fork (65) fixed connection of shifting, shift fork (65) of shifting are connected with shift block (63) of shifting and with shift block (63) synchronous motion, shift fork (65) joint of shifting is in the synchronizer gear sleeve of synchronous ware assembly (5).

3. The automatic gear shifting two-gear speed reducer matched with the new-energy pure electric vehicle as claimed in claim 2, wherein the gear shifting fork shaft (64) is fixedly connected with the gear shifting fork (65) through an elastic pin (66), and two ends of the gear shifting fork shaft (64) are in clearance fit with the front shell (1) and the rear shell (2) respectively, so that the gear shifting fork shaft (64) can move relative to the shells.

4. The automatic gear shifting two-gear speed reducer matched with the new-energy pure electric vehicle as claimed in claim 1, wherein the 1-gear driven gear (43) and the 2-gear driven gear (44) are respectively connected with the intermediate shaft (41) through needle bearings (46); the 1-gear driven gear (43) is fixedly connected with a 1-gear engaging tooth (431); the 2-gear driven gear (44) is fixedly connected with the 2-gear engaging teeth (441).

5. The automatic gear shifting two-gear speed reducer matched with the new-energy pure electric vehicle according to claim 4, wherein gear parameters of the 1-gear driving gear are as follows: normal modulus m_n1.9mm, reference circle normal pressure angle alpha_n20 DEG, pitch angle beta_n30 DEG, number of teeth of 1-gear driving gear on input shaft z₁₁Number of teeth z of 1-speed driven gear on intermediate shaft₁₂The gear ratio of gear 1 is 43/21-2.048.

6. The automatic gear shifting two-gear speed reducer matched with the new-energy pure electric vehicle according to claim 4, wherein gear parameters of the 2-gear driving gear are as follows: normal modulus m_n1.9mm, reference circle normal pressure angle alpha_n20 DEG, pitch angle beta_n30 DEG, number of teeth of 2-gear driving gear on input shaft z₂₁Number of teeth z of 2-speed driven gear on intermediate shaft 32₂₂The gear ratio of gear 2 is 33/32-1.031-33.

7. The automatic gear shifting two-gear speed reducer matched with the new energy pure electric vehicle is characterized in that the synchronizer assembly (5) comprises a synchronizer gear hub (51), a synchronizer gear sleeve (52), a 1-gear synchronizer cone ring (53), a synchronizer slider (54) and a 2-gear synchronizer cone ring (55), the synchronizer gear hub (51) is connected with the intermediate shaft (41) through an internal spline, the synchronizer slider (54) is slidably connected in a sliding groove in the periphery of the synchronizer gear hub (51), the synchronizer gear sleeve (52) is in key connection with an outer ring of the synchronizer gear hub (51), and the 1-gear synchronizer cone ring (53) and the 2-gear synchronizer cone ring (55) are respectively clamped on two end faces of the synchronizer gear hub (51).

8. The automatic gear shifting two-gear speed reducer matched with the new-energy pure electric vehicle as claimed in claim 1, wherein the differential assembly (7) comprises a main speed reducer driven gear (71), a planetary gear shaft (72), a planetary gear (73), a side gear (74), a differential half shaft (75) and a differential shell (77); a main reducer driven gear (71) is fixedly connected with a differential shell (77) through a cylindrical pin 78; the planet gear shaft (72) is connected to the differential case (77), a pair of planet gears (73) are fixed at two ends of the planet gear shaft (72), a pair of side gears (74) are respectively meshed with the planet gears (73) for transmission, and the side gears (74) are respectively fixedly connected with differential half shafts (75).

9. The automatic two-gear speed reducer matched with the new-energy pure electric vehicle according to claim 1, wherein the speed ratio of the automatic two-gear speed reducer is as follows:

under 1 gear, the gear ratio is 2.048; the main reduction ratio is 4.15; a total speed ratio of 8.498;

in the gear 2, the gear ratio is 1.031; the main reduction ratio is 4.15; a total speed ratio of 4.280;

under reverse gear, the gear ratio is 2.048; the main reduction ratio is 4.15; the overall speed ratio is 8.498.

Technical Field

The invention relates to a two-gear speed reducer, in particular to an automatic gear shifting two-gear speed reducer matched with a new energy pure electric vehicle, and belongs to the technical field of new energy vehicle speed reducers.

Background

For a new energy pure electric vehicle, the rotating speed range of a driving motor is wider, generally about 0-18000 r/min and even up to 20000r/min, the single-stage speed reducer can meet the requirements of low rotating speed and large torque driving, and high rotating speed and high-speed driving of the vehicle are realized, so that the global mainstream pure electric vehicle mostly adopts an integrated scheme of the driving motor and the single-stage speed reducer, but the single-stage speed reducer still has defects.

The single transmission ratio generally cannot simultaneously compromise the dynamic property and the economical efficiency of the pure electric vehicle. Under the working condition of the NEDC, the electric drive efficiency is about 84 percent, under the conditions of the highest vehicle speed and the lowest vehicle speed, the electric drive efficiency is generally reduced to be below 60 to 70 percent, and the electric energy is seriously wasted to reduce the endurance mileage; on the other hand, when the vehicle is traveling at high speed, the motor needs to maintain an extremely high rotational speed, which in turn causes mechanical problems such as noise and NVH. However, with the requirement of energy consumption and the like, the pure electric automobile is expected to gradually adopt a two-gear speed reducer in the future.

In order to improve the efficiency of electric drive and balance the cost of a motor, a speed reducer matched with a new energy pure electric vehicle needs to be designed, so that the efficiency in the process of low rotating speed and large torque can be ensured, and the efficiency in the process of high rotating speed and low torque can be considered.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides an automatic gear shifting two-gear speed reducer matched with a new energy pure electric vehicle.

The purpose of the invention is realized by the following technical scheme, which is combined with the attached drawings:

an automatic gear shifting two-gear speed reducer matched with a new energy pure electric vehicle comprises a front shell 1, a rear shell 2, an input shaft assembly 3, an intermediate shaft assembly 4, a synchronizer assembly 5, a gear shifting mechanism assembly 6 and a differential mechanism assembly 7; the input shaft assembly 3 comprises an input shaft 31, the input shaft 31 is connected with a driving motor of the whole vehicle, and the input shaft 31 is respectively provided with a 1-gear driving gear 32 and a 2-gear driving gear 33; the intermediate shaft assembly 4 comprises an intermediate shaft 41, a 1-gear driven gear 43 and a 2-gear driven gear 44 are respectively connected to the intermediate shaft 41 in a rotating mode, the 1-gear driven gear 43 is in meshing transmission with the 1-gear driving gear 32, and the 2-gear driven gear 44 is in meshing transmission with the 2-gear driving gear 33; the front section of the intermediate shaft 41 is provided with a main reducer driving gear 42; the synchronizer assembly 5 is fixed on the intermediate shaft and is positioned between the 1-gear driven gear 43 and the 2-gear driven gear 44; the gear shifting fork 65 of the gear shifting mechanism assembly 6 is clamped on the synchronizer gear sleeve 52 of the synchronizer assembly 5 and is used for controlling the synchronizer assembly 5 to be connected with the 1-gear driven gear 43 or the 2-gear driven gear 44 to realize gear selection; the differential assembly 7 is in meshing transmission with a final drive gear 42 of the intermediate shaft assembly 4 through a final drive driven gear 71, and outputs power from differential half shafts 75.

Further, the gear shift mechanism assembly 6 comprises a gear shift driving motor 61, a ball screw 62, a gear shift block 63, a gear shift fork shaft 64 and a gear shift fork 65; the ball screw 62 is connected with an output shaft of the gear shifting driving motor 61, the gear shifting block 63 is connected with the ball screw 62 and moves along the axial direction of the ball screw 62, the gear shifting fork shaft 64 is fixedly connected with the gear shifting fork 65, the gear shifting fork 65 is connected with the gear shifting block 63 and moves synchronously with the gear shifting block 63, and the gear shifting fork 65 is clamped on the synchronizer gear sleeve 52 of the synchronizer assembly 5.

Further, the shift rail 64 and the shift fork 65 are fixedly connected by a resilient pin 66, and both ends of the shift rail 64 are in clearance fit with the front housing 1 and the rear housing 2, respectively, so that the shift rail 64 can move relative to the housings.

Further, the 1-gear driven gear 43 and the 2-gear driven gear 44 are respectively connected with the intermediate shaft 41 through needle bearings 46; the 1-gear driven gear 43 is fixedly connected with a 1-gear engaging gear 431; a 2 nd gear engaging tooth 441 is fixedly connected to the 2 nd gear driven gear 44.

Further, the gear parameters of the 1 st gear driving gear are as follows: normal modulus m_n1.9mm, reference circle normal pressure angle alpha_n20 DEG, pitch angle beta_n30 DEG, number of teeth of 1-gear driving gear on input shaft z₁₁Number of teeth z of 1-speed driven gear on intermediate shaft₁₂The gear ratio of gear 1 is 43/21-2.048.

Further, the gear parameters of the 2-gear driving gear are as follows: normal modulus m_n1.9mm, reference circle normal pressure angle alpha_n20 DEG, pitch angle beta_n30 DEG, number of teeth of 2-gear driving gear on input shaft z₂₁Number of teeth z of 2-speed driven gear on intermediate shaft 32₂₂The gear ratio of gear 2 is 33/32-1.031-33.

Further, the synchronizer assembly 5 includes a synchronizer gear hub 51, a synchronizer gear sleeve 52, a 1-gear synchronizer cone ring 53, a synchronizer slider 54, and a 2-gear synchronizer cone ring 55, the synchronizer gear hub 51 is connected with the intermediate shaft 41 through an internal spline, the synchronizer slider 54 is slidably connected in a sliding groove on the periphery of the synchronizer gear hub 51, the synchronizer gear sleeve 52 is connected with an outer ring key of the synchronizer gear hub 51, and the 1-gear synchronizer cone ring 53 and the 2-gear synchronizer cone ring 55 are respectively clamped on two end faces of the synchronizer gear hub 51.

Further, the differential assembly 7 includes a final drive driven gear 71, planetary gear shafts 72, planetary gears 73, side gears 74, differential half shafts 75, a differential case 77; the final drive driven gear 71 is fixedly connected with a differential case 77 through a cylindrical pin 78; the planet shafts 72 are connected to a differential case 77, a pair of planet gears 73 are fixed to both ends of the planet shafts 72, a pair of side gears 74 are respectively meshed with the planet gears 73 for transmission, and differential half shafts 75 are respectively fixedly connected to the side gears 74.

Further, the speed ratio of the automatic gear shifting two-gear speed reducer is as follows:

under 1 gear, the gear ratio is 2.048; the main reduction ratio is 4.15; a total speed ratio of 8.498;

in the gear 2, the gear ratio is 1.031; the main reduction ratio is 4.15; a total speed ratio of 4.280;

under reverse gear, the gear ratio is 2.048; the main reduction ratio is 4.15; the overall speed ratio is 8.498.

The invention has the following beneficial effects:

the automatic gear shifting two-gear speed reducer matched with the new energy pure electric automobile is an automatic gear shifting cylindrical gear transmission electromechanical integrated speed reducer. The automatic gear shifting device has the advantages of being capable of automatically shifting gears, retaining the advantages of high gear transmission efficiency, low cost and outstanding reliability, effectively reducing the labor intensity of drivers and effectively reducing the operation cost of vehicles. The gear shifting mechanism adopts a roller screw gear shifter driven by a motor, and compared with other automatic gearboxes, the gear shifting mechanism has the advantages of low acquisition cost and obvious cost performance.

Drawings

FIG. 1 is a schematic axial-section structure view of an automatic gear shifting two-gear speed reducer matched with a new energy pure electric vehicle;

FIG. 2 is a schematic view of the input shaft assembly of the present invention;

FIG. 3 is a schematic view of an assembly structure of the countershaft assembly and the synchronizer assembly according to the present invention;

FIG. 4 is a schematic view of an assembly structure of the countershaft assembly with the synchronizer assembly and the shifting mechanism assembly according to the present invention;

FIG. 5 is a schematic view of a ball screw structure of the shifting mechanism assembly according to the present invention;

FIG. 6 is a schematic structural view of a 1-speed driven gear and a 2-speed driven gear according to the present invention;

FIG. 7 is a schematic view of a synchronizer assembly according to the present invention;

FIG. 8 is a schematic view of a differential assembly according to the present invention;

FIG. 9 is a schematic diagram of the working principle of the present invention;

in the figure:

1-front housing; 2-a rear housing; 3-an input shaft assembly; 4-a mid-shaft assembly; 5-a synchronizer assembly; 6-a gear shift mechanism assembly; 7-a differential assembly;

31-an input shaft; a 32-1 gear drive gear; a 33-2 gear driving gear; 34-deep groove ball bearing;

41-intermediate shaft; 42-main reducer drive gear; a 43-1 gear driven gear; 44-2 driven gear; 45-tapered roller bearings; 46-needle bearings; 47-a thrust washer; 431-1 gear engagement teeth; 441-2 gear engagement teeth;

51-synchronizer hub; 52-synchronizer sleeve gear; a 53-1 gear synchronizer cone ring; 54-synchronizer slide; a 55-2 gear synchronizer cone ring;

61-a shift drive motor; 62-ball screw; 63-a gear shifting block; 64-shift rail; 65-a shift fork; 66-a resilient pin; 621-a screw shaft; 622-ball nut; 623-a ball;

71-final drive driven gear; 72-planetary gear shafts; 73-planetary gear; 74-side gear; 75-differential half-shafts; 76-tapered roller bearings; 77-differential case; 78-cylindrical pin.

Detailed Description

The technical scheme of the invention is further explained by combining the accompanying drawings as follows:

the invention relates to an automatic gear shifting two-gear speed reducer matched with a new energy pure electric vehicle, which has the shape of length multiplied by width multiplied by height multiplied by 213 multiplied by 404 multiplied by 309, as shown in figure 1, and consists of parts such as a front shell 1, a rear shell 2, an input shaft assembly 3, an intermediate shaft assembly 4, a synchronizer assembly 5, a gear shifting mechanism assembly 6, a differential mechanism assembly 7 and the like, wherein the power of a driving motor of the whole vehicle is input by the speed reducer input shaft assembly, and is output from a differential half shaft of the differential mechanism assembly after passing through the intermediate shaft assembly.

As shown in fig. 1 to 8, the input shaft assembly 3 includes an input shaft 31, the input shaft 31 is connected to a driving motor of the entire vehicle, and the input shaft 31 is provided with a 1-gear driving gear 32 and a 2-gear driving gear 33 respectively; the intermediate shaft assembly 4 comprises an intermediate shaft 41, a 1-gear driven gear pair 43 and a 2-gear driven gear pair 44 are respectively connected to the intermediate shaft 41 in a rotating mode, the 1-gear driven gear pair 43 is in meshing transmission with the 1-gear driving gear 32, and the 2-gear driven gear pair 44 is in meshing transmission with the 2-gear driving gear 33; the front section of the intermediate shaft 41 is provided with a main reducer driving gear 42; the synchronizer assembly 5 is fixed on the intermediate shaft and is positioned between the driven gear pair 43 of the 1-gear and the driven gear pair 44 of the 2-gear; the gear shifting mechanism assembly 6 is assembled on the synchronizer assembly 5 and is used for controlling the synchronizer assembly 5 to be connected with the 1-gear driven gear pair 43 or the 2-gear driven gear pair 44 to realize gear selection; the differential assembly 7 is in meshing transmission with a final drive gear 42 of the intermediate shaft assembly 4 through a final drive driven gear 71, and outputs power from differential half shafts 75.

Further, as shown in fig. 4 and 5, the shift mechanism assembly 6 includes a shift driving motor 61, a ball screw 62, a shift block 63, a shift fork shaft 64, and a shift fork 65; the ball screw 62 is connected with an output shaft of the gear shifting driving motor 61, the gear shifting block 63 is connected with the ball screw 62 and moves along the axial direction of the ball screw 62, the gear shifting fork shaft 64 is fixedly connected with the gear shifting fork 65, the gear shifting fork 65 is connected with the gear shifting block 63 and moves synchronously with the gear shifting block 63, and the gear shifting fork 65 is clamped on a synchronizer gear sleeve of the synchronizer assembly 5. The gear shifting lead screw is a ball lead screw, sliding friction is converted into rolling friction, gear shifting is flexible, and noise is low.

Further, the shift rail 64 and the shift fork 65 are fixedly connected by a resilient pin 66, and both ends of the shift rail 64 are in clearance fit with the front housing 1 and the rear housing 2, respectively, so that the shift rail 64 can move relative to the housings.

Further, two ends of the input shaft assembly 3 are respectively connected with the front housing 1 and the rear housing 2 through deep groove ball bearings 34.

Further, the front and rear ends of the intermediate shaft 41 are connected to the front housing 1 and the rear housing 2 through needle bearings 45, respectively.

Further, a thrust washer 47 is provided between the 2 nd speed driven gear 44 and the needle bearing 45.

Further, the 1-gear driven gear 43 and the 2-gear driven gear 44 are respectively connected with the intermediate shaft 41 through needle bearings 46; as shown in fig. 6, a 1 st gear engaging tooth 431 is fixedly connected to the 1 st gear driven gear 43; the 2 nd gear driven gear 4 is fixedly connected with a 2 nd gear engaging tooth 441.

Further, the gear parameters of the 1 st gear driving gear are as follows: normal modulus m_n1.9mm, reference circle normal pressure angle alpha_n20 DEG, pitch angle beta_n30 DEG, number of teeth of 1-gear driving gear on input shaft z₁₁Number of teeth z of 1-speed driven gear on intermediate shaft₁₂The gear ratio of gear 1 is 43/21-2.048.

The 2-gear driving gear has the following gear parameters: normal modulus m_n1.9mm, reference circle normal pressure angle alpha_n20 DEG, pitch angle beta_n30 DEG, number of teeth of 2-gear driving gear on input shaft z₂₁Number of teeth z of 2-speed driven gear on intermediate shaft 32₂₂The gear ratio of gear 2 is 33/32-1.031-33.

Further, as shown in fig. 7, the synchronizer assembly 5 includes a synchronizer hub 51, a synchronizer sleeve 52, a 1-gear synchronizer cone ring 53, a synchronizer slider 54, and a 2-gear synchronizer cone ring 55, the synchronizer hub 51 is connected with the intermediate shaft 41 through an internal spline, the synchronizer slider 54 is slidably connected in a sliding groove at the periphery of the synchronizer hub 51, the synchronizer sleeve 52 is in key connection with an outer ring of the synchronizer hub 51, and the 1-gear synchronizer cone ring 53 and the 2-gear synchronizer cone ring 55 are respectively clamped on two end faces of the synchronizer hub 51.

Further, as shown in fig. 8, the differential assembly 7 includes final drive driven gears 71, planetary gear shafts 72, planetary gears 73, side gears 74, differential half shafts 75, a differential case 77; the final drive driven gear 71 is fixedly connected with a differential case 77 through a cylindrical pin 78; the planet shafts 72 are connected to a differential case 77, a pair of planet gears 73 are fixed to both ends of the planet shafts 72, a pair of side gears 74 are respectively meshed with the planet gears 73 for transmission, and differential half shafts 75 are respectively fixedly connected to the side gears 74.

Further, the speed ratio of the present invention is shown in table 1:

TABLE 1

The working principle of the invention is briefly explained as follows:

the main parameters of the present invention are shown in table 2.

TABLE 2

Product type	2T-220
		Number of gear positions	2
Control mode	Motor drive
		Rated input torque	220N.m
Weight (D)	28kg
		Type/charge of lubricating oil	SAE 75W-90GL-4/1.2L
Transmission efficiency	≥98％

As shown in fig. 3 and 4, the speed reducer has two gears, and when the synchronizer is engaged into the 1-gear side by the shifting fork, the 1-gear pair works to transmit the 1-gear torque and the rotating speed; when the synchronizer is hung on the 2-gear side by the shifting fork, the 2-gear pair works to transmit 2-gear torque and rotating speed; when the shifting fork and the synchronizer are in the middle position, the shifting fork and the synchronizer are in a neutral gear, and the speed reducer does not transmit torque and rotating speed.

As shown in fig. 9, when gear shifting is required, the VCU of the whole vehicle sends an instruction, the gear shifting driving motor works to drive the ball screw to rotate, the gear shifting block is made to move axially, the gear shifting fork is shifted to move, the synchronizer gear sleeve is pushed to move, the synchronizer cone ring is in friction with the joint teeth of the driven gear, and the synchronizers are shifted when the rotating speeds of the two ends are the same. The shifting motor rotates forwards and reversely to enable the shifting block to move back and forth, so that gear engaging and gear disengaging are achieved.

When the 1-gear is engaged, power is input from the input shaft, sequentially passes through a 1-gear driving gear of the input shaft, a 1-gear driven gear on the intermediate shaft, the synchronizer, the intermediate shaft, a driving gear of the main speed reducer, a driven gear of the main speed reducer on the differential assembly, the half axle gear and the differential half axle, and is output to a driving shaft of the whole vehicle.

When the 2-gear is engaged, power is input from an input shaft, sequentially passes through a 2-gear driving gear on the input shaft, a 2-gear driven gear on an intermediate shaft, a synchronizer, the intermediate shaft, a main speed reducer driving gear, a main speed reducer driven gear on a differential assembly, a half shaft gear and a differential half shaft, and is output to a driving shaft of the whole vehicle.