CN208535131U - A kind of electric drive list gear reducer structure with neutral gear - Google Patents

Abstract

The utility model provides a kind of electric drive list gear reducer structure with neutral gear, reducer shell is made of procapsid and back casing assembly, transmission mechanism is arranged in reducing gearbox body, input axle assembly connects and composes transmission mechanism by countershaft assembly and export axle assembly, input axle assembly, countershaft assembly and export axle assembly parallel arrangement, export axle assembly is fixedly connected with a differential mechanism, shift execution system includes the synchronizer system inside reducer shell, selector fork and leading screw and nut mechanism and the shift motor outside reducer shell, selector fork passes through the output axis connection of leading screw and nut mechanism and shift motor, synchronizer system is connect with countershaft assembly, selector fork stirs synchronizer system to realize the disconnection or engagement of power transmitting, input axle assembly connect to transmit with external motor output shaft Power；The utility model is compact-sized, integrated level is high, bearing capacity is strong, is highly convenient for vehicle space layouts at different levels.

Description

A kind of electric drive list gear reducer structure with neutral gear

Technical field

The utility model belongs to car deceleration device technical field, is related to a kind of electric drive list gear retarder with neutral gear, can For the 4 wheel drivens vehicle such as pure electric automobile, hybrid vehicle.

Background technique

With economic rapid growth, China Automobile Industry was swift and violent in recent years, production and marketing hits new peak continuously.Good market manifestation And requirement of the government policy regulation for energy-saving and environmental protection etc., constantly push the high speed development of automotive engineering.New energy Automobile becomes following development trend, and wherein pure electric automobile is the main development route of China's selection, therefore is developed advanced The core systems such as motor and retarder become groundwork, and wherein speed reducer for electric vehicle is in the side such as dynamic property, economy of vehicle Face plays key effect.

Currently, home and abroad in the market pure electric automobile with two drive based on, but more and more enterprises are gradually developing pure electricity Dynamic 4 wheel driven vehicle.Pure electric vehicle 4-wheel driven car is broadly divided into hub motor technology path and front axle, rear axle independent electric drive route, existing rank Section is influenced by factors such as cost and technological difficulties, based on front axle, rear axle independent electric drive 4 wheel driven technology path.For 4 wheel driven Vehicle, for the course continuation mileage for promoting vehicle, it is desirable that 4 wheel driven vehicle can be switched to two drive modes at any time when inessential, reduce vehicle Power consumption.

Currently, electric drive list gear retarder in the market is without neutral gear, yet no-clutch between motor and retarder can not Realize the power transmission path interruptions of motor and retarder, i.e. rotor part passes through retarder, transmission shaft and vehicle always Wheel connection, even if causing vehicle when two drive mode operation in this way, wheel must drag retarder and motor by the way that transmission shaft is counter Rotor portion rotation, because rotor inertia is very big, necessarily causes energy consumption of vehicles to increase, and course continuation mileage reduces.

Summary of the invention

The utility model aim is to provide a kind of electric drive list gear retarder with neutral gear, for pure electric automobile, mixing The 4 wheel drivens such as power vehicle vehicle is, it can be achieved that vehicle front axle or rear axle wheel and the real-time disconnection of power drive system and engage, guarantee While vehicle accelerating ability and special road conditions passability, it is continuous to promote vehicle for the energy loss of four-wheel drive system when reducing inessential Navigate mileage.

The utility model adopts the following technical scheme that realization:

A kind of electric drive list gear reducer structure with neutral gear, which is characterized in that reducer shell is by procapsid and rear shell Body assembly is constituted, and transmission mechanism is arranged in reducing gearbox body, and input axle assembly is connected by countershaft assembly and export axle assembly Composition transmission mechanism is connect, input axle assembly, countershaft assembly and export axle assembly are arranged in parallel, and are disposed with difference in export axle assembly Fast device, shift execution system include synchronizer system, selector fork and the leading screw and nut mechanism inside the reducer shell with And the shift motor outside reducer shell, selector fork are connected by the output shaft of leading screw and nut mechanism and shift motor It connects, synchronizer system is connect with countershaft assembly, and selector fork stirs synchronizer system to realize the disconnected of reducer power transmitting It opens or engages, input axle assembly connect to transmit power with external motor output shaft.

Further technical solution includes:

Input axle assembly includes input shaft and level-one driving gear, and input shaft and level-one driving wheel are integral type, input shaft Axial position be located at close to one end of external motor, before the front end of input shaft is supported on by a high speed deep groove ball bearing In shell, the rear end of input shaft is supported in back casing by a high speed deep groove ball bearing；

The countershaft assembly includes a jackshaft, and jackshaft is equipped with level-one driven gear and second level driving tooth Wheel, second level driving gear and jackshaft are integral type, and the bushing of shoulder block is provided on jackshaft, is equipped with needle roller axis on bushing It holds, level-one driven wheel then passes through needle bearing and is supported on jackshaft, and level-one driven wheel is engaged with level-one driving gear, in level-one There is synchronizer system suit to be fixed on jackshaft between driven gear and second level driving gear, is welded on level-one driven gear Gear ring is engaged, powerdriven engagement or disconnection, jackshaft are realized in the cooperation that engagement gear ring passes through and the tooth of synchronizer system covers In the front housing by a ball bearing support, intermediate shaft rear end is supported in back casing by another ball bearing for front end, in Between the ball bearing of axis, bushing and jackshaft front end axial restraint is carried out by locking nut；

Export axle assembly includes second level driven gear, differential mechanism and two tapered roller bearings, wherein second level driven tooth It takes turns and is integrated with the differential casing of differential mechanism by multiple rivet interlacements, differential casing passes through former and later two taper rollers For bearing support on retarder procapsid and back casing, differential casing is equivalent to the output shaft of export axle assembly, and second level is driven Gear is engaged with second level driving gear；

The differential mechanism is by two axle shaft gears in differential carrier body, a planetary gear shaft, two planet teeth Wheel, two axle shaft gear gaskets, two planet gear pads, a spring catch are constituted, and two of them axle shaft gear supports respectively The left and right both ends of differential casing are mounted on, two are respectively arranged with an axle shaft gear pad between axle shaft gear and differential casing Piece, two planetary gears are located in differential casing by planetary gear shaft, and planetary gear is engaged with axle shaft gear, planet tooth Wheel shaft upper end the axially position on differential casing, contact of two planetary gears with differential casing are realized by spring catch Place has a planet gear pad to be sleeved in planetary gear shaft respectively；

The shift execution system is made of synchronizer system, selector fork, leading screw and nut mechanism, shift motor, synchronous Device system is made of tooth hub, tooth set, sliding block with synchronous ring, and tooth hub is connect by spline with jackshaft interference, and tooth set passes through spline With tooth hub transmitting torque and can sliding axially along jackshaft, synchronization ring internal conical surface formed with the outer conical surface for engaging gear ring Friction is secondary；Three sliding blocks are located on tooth hub 3 along the uniformly distributed groove of tooth hub circumferencial direction, promotion when tooth set slides axially Slide block movement, so push synchronous ring internal conical surface with engage gear ring outer conical surface friction, to realize that tooth covers and engages gear ring Revolving speed it is synchronous.

Input shaft uses hollow shaft structure, the outer flower that input shaft passes through the internal spline of front end and the output shaft of external motor It is keyed to transmit power, input shaft rear end inner hole is equipped with bowl-type patch, realizes seal oil.

The selector fork welds together with a shift fork axle, and shift fork axle is supported on procapsid by two slide bushings On back casing, bore ends have internal screw thread in shift fork axle, and shift fork axle and wire rod thread connect and compose leading screw and nut mechanism, screw rod Rear end is fixedly connected with the output shaft of shift motor, is rotated by motor driven screw rod, the fixed shift fork axle in one end of selector fork The middle part of external cylindrical surface, the other end of selector fork are mounted in the fork slot of tooth set, and when screw rod rotation, shift fork axle is by screw rod Rotary motion be converted into along axial linear motion, covered and the engagement or disconnection that engage gear ring, realization by shift fork with movable tooth Reducer power transmitting disconnects or engagement.

Compared with prior art the beneficial effects of the utility model are:

Single gear retarder transmission mechanism of the utility model uses two-stage The gear deceleration, and triple axle parallel arrangement passes through The relative position of three shaftings of calculation optimization, under the premise of meeting maximum input torque 350Nm intensity requirement, guarantee input shaft with , away from only 150mm, pacify than existing market with the retarder of torque away from minimum, input with output installation center at the center of output shaft Dress is very beneficial for the lesser vehicle arrangement matching of front overhang, rear overhang length away from 50mm or more is reduced.The utility model passes through optimization The axial position and shift execution system arrangement relation of shafting gear, guarantee that speed reducer assembly axial dimension minimizes, controllably System is convenient for lesser A grades of beam width or less arrangement within 245mm.The retarder shift of the utility model executes system System dexterously integrates a set of leading screw and nut mechanism with selector fork, has characteristics of compact layout, components few, at low cost, It is easily achieved the advantages such as shift control.In conclusion the compact of the utility model, large torque, band neutral gear list gear retarder have Beneficial to vehicle space layouts at different levels, especially for the following forward and backward lesser pure electric vehicle vehicle platform of outstanding size, application Prospect is extensive.Carrying the 4 wheel drivens vehicles such as pure electric vehicle, the hybrid power of the retarder can be in the premise for meeting dynamic property and passability Under, the energy loss of vehicle is reduced, battery durable mileage is promoted.

Detailed description of the invention

The utility model will be further described below with reference to the accompanying drawings:

Fig. 1 is the external structure schematic diagram that a kind of electric drive list with neutral gear described in the utility model keeps off retarder；

Fig. 2 is the assembly relation schematic diagram that a kind of electric drive list with neutral gear described in the utility model keeps off retarder；

Fig. 3 is the axial sectional view that a kind of electric drive list with neutral gear described in the utility model keeps off retarder；

Fig. 4 is the assembly for the shift execution system that a kind of electric drive list with neutral gear described in the utility model keeps off retarder Relation schematic diagram；

Fig. 5 is the axial direction for the shift execution system that a kind of electric drive list with neutral gear described in the utility model keeps off retarder Cross-sectional view；

Fig. 6 is the synchronizer system assembly relation that a kind of electric drive list with neutral gear described in the utility model keeps off retarder Schematic diagram；

In figure: 1. transmission mechanisms, 2. differential mechanisms, 3. shift execution systems, 4. procapsids, 5. back casings, 11. input shafts are total At, 12. countershaft assemblies, 13. export axle assemblies, 20. differential casings, 21. axle shaft gears, 22. planetary gear shafts, 23. rows Star gear, 24. axle shaft gear gaskets, 25. planet gear pads, 26. spring catch, 31. synchronizer systems, 32. selector forks, 33. leading screw and nut mechanism, 34. shift motors, 111. input shafts, 112. level-one driving gears, 113. high speed deep groove ball bearings, 114. internal spline, 115. bowl-type patches, 121. jackshafts, 122. level-one driven gears, 123. second level driving gears, 124. linings Set, 125. needle bearings, 127. engagement gear rings, 128. ball bearings, 129. locking nuts, 131. second level driven gears, 132. rivetings Nail, 133. tapered roller bearings, 311. tooth hubs, 312. tooth sets, 313. sliding blocks, 314. synchronous rings, 321. shift fork axles, 331. is sliding Dynamic bushing, 332. screw rods.

Specific embodiment

The utility model is explained in detail with reference to the accompanying drawing:

It is with reference to the accompanying drawing to be specifically described to the technical solution of the utility model: a kind of electric drive list with neutral gear Reducer structure is kept off, is made of transmission mechanism 1, differential mechanism 2, shift execution system 3, procapsid 4 and back casing 5.The biography Motivation structure uses double reduction gear, uses triple axle and is arranged in parallel, including input axle assembly 11, countershaft assembly 12 And export axle assembly 13.

As shown in Figure 2 and Figure 4, procapsid 4 and the assembly of back casing 5 constitute the reducer shell of the utility model, driver Structure 1 is arranged in reducing gearbox body, and input axle assembly 11 connects and composes transmission by countershaft assembly 12 and export axle assembly 13 Mechanism 1, input axle assembly 11, countershaft assembly 12 and export axle assembly 13 are arranged in parallel, and are disposed with difference in export axle assembly 13 Fast device 2, shift execution system 3 include synchronizer system 31, selector fork 32 and the feed screw nut inside reducer shell Mechanism 33 and the shift motor 34 outside reducer shell, selector fork 32 pass through leading screw and nut mechanism 33 and shift electricity The output axis connection of machine 34, synchronizer system 31 are connect with countershaft assembly 12, selector fork 32 stir synchronizer system 31 with Realize the disconnection or engagement of reducer power transmitting, input axle assembly 11 connect to transmit power with external motor output shaft.

As shown in Fig. 2, input axle assembly 11 includes input shaft 111 and level-one driving gear 112, input shaft 111 and level-one Driving wheel 112 is integral type, and the axial position of input shaft 111 is located at close to motor side, and 111 front end of input shaft passes through a height Fast deep groove ball bearing 113 is supported in procapsid 4, and the rear end of input shaft 111 is supported on by a high speed deep groove ball bearing 113 In back casing 5, input shaft 111 uses hollow structure, passes through 111 front end internal spline 114 of input shaft and external motor output shaft External splines connection transmit power, 111 rear end inner hole of input shaft is equipped with bowl-type patch 115, realize seal oil.

The countershaft assembly 12 includes a jackshaft 121, and countershaft assembly 12 is equipped with level-one driven gear 122 And second level driving gear 123, second level driving gear 123 and jackshaft 121 are integral type, are provided with shoulder block on jackshaft 121 Bushing 124, needle bearing 125 is installed, level-one driven wheel 122 is then supported on centre by needle bearing 125 on bushing 124 On axis 121, level-one driven wheel 122 is engaged with level-one driving gear 112, in level-one driven gear 122 and second level driving gear 123 Centre is equipped with the suit of synchronizer system 31 and is fixed on jackshaft 121, and engagement gear ring 127 is welded on level-one driven gear 125, Gear ring 127 is engaged by the cooperation with the tooth set 312 in synchronizer system 31, realizes powerdriven engagement or disconnection, it is intermediate 121 both ends of axis pass through a ball bearing 128 respectively and are supported in procapsid 4 and back casing 5, jackshaft 121, bushing 124 and in Between the ball bearing 128 of 121 front end of axis axial restraint is carried out using locking nut 129.

As shown in Fig. 2, export axle assembly 13 is by second level driven gear 131, differential mechanism 2 and two tapered roller bearings 133 Composition, wherein second level driven gear 131 and the differential casing 20 of differential mechanism 2 are connected as one by multiple rivets 132, differential Device shell 20 is supported on retarder procapsid 4 and back casing 5 by former and later two tapered roller bearings 133, differential casing 20 are equivalent to the output shaft of export axle assembly 13, and second level driven gear 131 is engaged with second level driving gear 123.

As shown in Fig. 2, the differential mechanism 2 is then by two axle shaft gears, 21, planets in differential casing 20 24, two, axle shaft gear gasket, 26 structure of spring catch of planet gear pad 25, one of planetary gear 23, two of gear shaft 22, two At., two of them axle shaft gear 21 supports the left and right both ends for being mounted on differential casing 20 respectively, two axle shaft gears 21 with An axle shaft gear gasket 24 is respectively arranged between differential casing 20, two planetary gears 23 are located in by planetary gear shaft 22 In differential casing 20, planetary gear 23 is engaged with axle shaft gear 24, and 22 upper end of planetary gear shaft is realized by spring catch 26 There is a planet tooth in the contact position of axially position on differential casing 20, two planetary gears 23 and differential casing 20 respectively Wheel gasket 25 is sleeved in planetary gear shaft 22；

As shown in Figure 4, Figure 5 and Figure 6, the shift execution system 3 is by synchronizer system 31, selector fork 32, screw rod spiral shell Parent agency 33, shift motor 34 form.The synchronizer system 31 is by tooth hub 311, tooth set 312, sliding block 313, synchronous ring 314 Composition, synchronizer system 31 are made of tooth hub 311, tooth set 312, sliding block 313 with synchronous ring 314, and tooth hub 311 is by spline in Between 121 interference of axis connect, tooth set 312 transmits torque by spline and tooth hub 311, and can sliding axially along jackshaft 121, It is secondary that the internal conical surface of synchronous ring 314 can form friction with the outer conical surface for engage gear ring 127, realize tooth cover 312 with engage gear ring Revolving speed when 127 engagement is synchronous.Three sliding blocks 313 are located on tooth hub 311 3 along uniformly distributed recessed of 311 circumferencial direction of tooth hub In slot, tooth set 312 pushes sliding block 313 to move when sliding axially, so push synchronous 314 internal conical surface of ring with engage gear ring 127 Outer conical surface friction, to realize that tooth set 312 is synchronous with the engagement revolving speed of gear ring 127.

Such as Fig. 4, Fig. 5 and Fig. 6, so, the selector fork 32 welds together with shift fork axle 321, and shift fork axle 321 passes through Two slide bushings 331 are supported on procapsid 4 and back casing 5, and bore ends have internal screw thread in shift fork axle 321, are equivalent to one A nut, shift fork axle 321 is threadedly coupled with screw rod 332 constitutes leading screw and nut mechanism 33,332 rear end of screw rod and shift motor 34 Output shaft be fixedly connected, pass through shift motor 34 and screw rod 332 driven to rotate, the fixed shift fork axle 321 in one end of selector fork 32 The middle part of external cylindrical surface, the other end of selector fork 32 are mounted in the fork slot of tooth set 312, and shift fork axle 321 is due to shift fork 32 Being mounted on tooth and covering can not rotate in 312 fork slots, therefore when screw rod 332 rotates, shift fork axle 321 transports the rotation of screw rod 332 Turn changes into along axial linear motion, with movable tooth set 312 and the engagement or disconnection that engage gear ring 127, realization by shift fork 32 Reducer power transmitting disconnects or engagement.

Vehicle by two drive pattern switchings be 4 wheel driven mode when driving, shift motor 34 is sent commands to by controller, shift gears Motor 34, which rotates in the forward direction, drives screw rod 332 to rotate, and converts rotational motion into linear motion by feed screw nut pair principle, i.e., The rotation of screw rod 332 drives shift fork axle 321 to move axially, and then by selector fork 32 with 312 axial movement of movable tooth set, tooth set Synchronous ring 314 is pressed on the circular conical surface of engagement gear ring 127 by 312 promotion sliding block 313 movements, realizes synchronous ring by tribology principle 314 is synchronous with engagement gear ring revolving speed, and completion synchronizes rear tooth set 312 and continues to be moved axially until and engage the engagement of gear ring 127, i.e., complete At movement of putting into gear, to realize that vehicle power is transmitted to wheel by two-stage The gear deceleration, transmission shaft by power motor.Transmitting. On the contrary, equally sending commands to shift motor 34 by controller when vehicle drives mode by 4 wheel driven pattern switching for two, passing through shift Motor 34, which reversely rotates, drives screw rod 332 to rotate, and then is axially transported with movable tooth set 312 along gear direction is plucked by selector fork 32 It is dynamic, until tooth set 312 is disconnected with gear ring 127 is engaged, realizes that retarder drive path disconnects, save energy consumption of vehicles, increase Course continuation mileage.

Claims (6)

1. a kind of electric drive list with neutral gear keeps off reducer structure, which is characterized in that reducer shell is by procapsid (4) and rear shell Body (5) assembly is constituted, and transmission mechanism (1) is arranged in reducing gearbox body, and input axle assembly (11) passes through countershaft assembly (12) It is connected and composed transmission mechanism (1) with export axle assembly (13), input axle assembly (11), countershaft assembly (12) and export axle assembly (13) it is arranged in parallel, is disposed with differential mechanism (2) in export axle assembly (13), shift execution system (3) includes being located at reducing gearbox Synchronizer system (31), selector fork (32) and the leading screw and nut mechanism (33) in internal portion and outside reducer shell Shift motor (34), selector fork (32) passes through the output axis connection of leading screw and nut mechanism (33) and shift motor (34), synchronous Device system (31) is connect with countershaft assembly (12), and selector fork (32) stirs synchronizer system (31) to realize reducer power The disconnection or engagement of transmitting, input axle assembly (11) connect to transmit power with external motor output shaft.

2. a kind of electric drive list with neutral gear according to claim 1 keeps off reducer structure, which is characterized in that input shaft is total It include input shaft (111) and level-one driving gear (112) at (11), input shaft (111) is integrated with level-one driving wheel (112) Formula, the axial position of input shaft (111) are located at close to one end of external motor, and the front end of input shaft (111) passes through a height Fast deep groove ball bearing (113) is supported in procapsid (4), and the rear end of input shaft (111) passes through a high speed deep groove ball bearing (113) it is supported in back casing (5)；

The countershaft assembly (12) includes a jackshaft (121), and jackshaft (121) is equipped with level-one driven gear (122) and second level driving gear (123), second level driving gear (123) and jackshaft (121) are integral type, on jackshaft (121) It is provided with the bushing (124) of shoulder block, is equipped with needle bearing (125) on bushing (124), level-one driven wheel (122) then passes through Needle bearing (125) is supported on jackshaft (121), and level-one driven wheel (122) is engaged with level-one driving gear (112), one There is synchronizer system (31) suit to be fixed on jackshaft (121) between grade driven gear (122) and second level driving gear (123) On, engagement gear ring (127) is welded on level-one driven gear (125), engagement gear ring (127) passes through and synchronizer system (31) The cooperation of tooth set (312), realizes powerdriven engagement or disconnection, and jackshaft (121) front end passes through ball bearing (128) branch Support is in procapsid (4), and jackshaft (121) rear end is supported in back casing (5) by another ball bearing (128), jackshaft (121), bushing (124) and the ball bearing (128) of jackshaft (121) front end are carried out axial solid by a locking nut (129) It is fixed；

Export axle assembly (13) includes second level driven gear (131), differential mechanism (2) and two tapered roller bearings (133), Middle second level driven gear (131) and the differential casing (20) of differential mechanism (2) are connected as one by multiple rivets (132), poor Fast device shell (20) is supported on retarder procapsid (4) and back casing (5) by former and later two tapered roller bearings (133), Differential casing (20) is equivalent to the output shaft of export axle assembly (13), second level driven gear (131) and second level driving gear (123) it engages.

3. a kind of electric drive list with neutral gear according to claim 2 keeps off reducer structure, which is characterized in that the differential Device (2) is by two axle shaft gears (21), the planetary gear shaft (22), two planetary gears in differential casing (20) (23), two axle shaft gear gaskets (24), two planet gear pads (25), a spring catch (26) are constituted, two of them half Shaft gear (21) supports the left and right both ends for being mounted on differential casing (20), two axle shaft gears (21) and differential carrier respectively An axle shaft gear gasket (24) is respectively arranged between body (20), two planetary gears (23) are located in by planetary gear shaft (22) In differential casing (20), planetary gear (23) is engaged with axle shaft gear (24), and planetary gear shaft (22) upper end passes through spring catch (26) axially position on differential casing (20), the contact position of two planetary gears (23) and differential casing (20) are realized There is a planet gear pad (25) to be sleeved on planetary gear shaft (22) respectively.

4. a kind of electric drive list with neutral gear according to claim 2 keeps off reducer structure, which is characterized in that the shift Execution system (3) is made of synchronizer system (31), selector fork (32), leading screw and nut mechanism (33), shift motor (34), together Step device system (31) is made of tooth hub (311), tooth set (312), sliding block (313) with synchronous ring (314), and tooth hub (311) passes through flower Key is connect with jackshaft (121) interference, and tooth set (312) transmits torque by spline and tooth hub (311) and can be along jackshaft (121) Slide axially, the internal conical surface of synchronous ring (314) forms the pair that rubs with the outer conical surface for engage gear ring (127)；Three sliding blocks (313) tooth hub (311) upper 3 are located at along the uniformly distributed groove of tooth hub (311) circumferencial direction, tooth set (312) slides axially When push sliding block (313) movement, and then push synchronous ring (314) internal conical surface with engage gear ring (127) outer conical surface friction, from And realize that tooth set (312) is synchronous with the engagement revolving speed of gear ring (127).

5. a kind of electric drive list with neutral gear according to claim 2 keeps off reducer structure, which is characterized in that input shaft (111) hollow shaft structure, the outer flower that input shaft (11) passes through the internal spline (114) of front end and the output shaft of external motor are used It is keyed to transmit power, input shaft (11) rear end inner hole is equipped with bowl-type patch (115), realizes seal oil.

6. a kind of electric drive list with neutral gear according to claim 4 keeps off reducer structure, which is characterized in that the shift Shift fork (32) welds together with a shift fork axle (321), before shift fork axle (321) is supported on by two slide bushings (331) On shell (4) and back casing (5), shift fork axle (321) interior bore ends have internal screw thread, shift fork axle (321) and screw rod (332) screw thread It connects and composes leading screw and nut mechanism (33), screw rod (332) rear end is fixedly connected with the output shaft of shift motor (34), passes through motor (34) driving screw rod (332) rotation, the middle part of fixed shift fork axle (321) external cylindrical surface in one end of selector fork (32), shift are dialled The other end of fork (32) is mounted in the fork slot of tooth set (312), and when screw rod (332) rotation, shift fork axle (321) is by screw rod (332) rotary motion is converted into along axial linear motion, by shift fork (32) band movable tooth set (312) with engage gear ring (127) engagement or disconnection realize that reducer power transmitting is disconnected or engaged.