CN106801736B

CN106801736B - Differential mechanism

Info

Publication number: CN106801736B
Application number: CN201710215093.3A
Authority: CN
Inventors: 凌子龙
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-04-02
Filing date: 2017-04-02
Publication date: 2023-01-10
Anticipated expiration: 2037-04-02
Also published as: CN106801736A

Abstract

The invention relates to a differential mechanism, in particular to a differential mechanism capable of being used for automobiles, which consists of an internal gear pair consisting of a shell, a swing gear A and an output gear A, an internal gear pair consisting of a swing gear B and an output gear B, at least two A-type intermediate gears and at least two B-type intermediate gears, wherein the shell is provided with a first gear and a second gear; the radial direction of each A-type intermediate gear is fixed with the shell, the rotation axis of each A-type intermediate gear is parallel to the rotation axis of the shell, each A-type intermediate gear is meshed with at least one B-type intermediate gear, the gear pair gear ratio formed by the A-type intermediate gear and the B-type intermediate gear is the same, each A-type intermediate gear is provided with an eccentric shaft of which the axis is parallel to the rotation axis of each A-type intermediate gear, the distance of the eccentric shaft on each A-type intermediate gear relative to the rotation axis of the gear is the same, the phases of the eccentric shafts on all the A-type intermediate gears are the same, the eccentric shaft on each A-type intermediate gear is radially fixed with the swing gear A, and the output gear A is coaxial with the rotation axis of the shell.

Description

Differential mechanism

Technical Field

The invention relates to a differential mechanism, in particular to a differential mechanism capable of being used for an automobile, and belongs to the technical field of mechanical transmission parts.

Background

The differential is a mechanical transmission part, is mostly used for transmitting the power output by an automobile gearbox to two or four driving wheels, the pressing tracks of the driving wheels are different due to the uneven road surface, the turning of the vehicle and other reasons, if the driving wheels rotate at the same speed, the friction between the wheels and the road surface is increased, and the driving resistance of the vehicle is increased, so the differential needs to output the rotating speed to the wheels according to different operating conditions of each driving wheel, and most of the traditional differentials are helical gears or crown gear structures.

The Limited Slip Differential is called Limited Slip Differential, LSD for short. A limited slip differential, which is an improved differential for limiting wheel slip, means that the difference of the rotation speed of the driving wheel is allowed in a certain range to ensure the driving performance such as normal turning, but when some driving wheel slips or hangs, the differential can be limited not to output all power to the slipping or hanging wheel, which is helpful for the control of the vehicle when getting rid of difficulties and driving violently. For example, when a wheel of a vehicle falls into a pit, the wheel has no friction, but the grounded wheel has a relatively large resistance, and the normal differential functions to return all power to the low friction wheel. The wheels falling into the pot hole can rotate continuously, the land wheel can not act at all, and therefore the wheels cannot run, and the situation can not happen if the limited slip differential is assembled on the vehicle. The current limited slip differential uses an electric control multi-plate clutch to realize locking, and also realizes locking by a purely mechanical worm gear.

Disclosure of Invention

The invention provides a differential mechanism, which adopts the following specific technical scheme.

A differential mechanism comprises a shell, an internal gear pair consisting of a swing gear A and an output gear A, an internal gear pair consisting of a swing gear B and an output gear B, at least two A-type intermediate gears and at least two B-type intermediate gears; the radial direction of each A-type intermediate gear is fixed with the shell, the rotation axis of each A-type intermediate gear is parallel to the rotation axis of the shell, each A-type intermediate gear is meshed with at least one B-type intermediate gear, the gear pair gear ratio formed by the A-type intermediate gear and the B-type intermediate gear is the same, each A-type intermediate gear is provided with an eccentric shaft of which the axis is parallel to the rotation axis of each A-type intermediate gear, the distance of the eccentric shaft on each A-type intermediate gear relative to the rotation axis of the gears is the same, the phases of the eccentric shafts on all the A-type intermediate gears are the same, the eccentric shaft on each A-type intermediate gear is radially fixed with the swing gear A, and the output gear A is coaxial with the rotation axis of the shell; the radial direction of each B-type intermediate gear is fixed with the shell, the rotation axis of each B-type intermediate gear is parallel to the rotation axis of the shell, each B-type intermediate gear is meshed with at least one A-type intermediate gear, each B-type intermediate gear is provided with an eccentric shaft, the axis of each B-type intermediate gear is parallel to the rotation axis of each B-type intermediate gear, the distance between the eccentric shaft on each B-type intermediate gear and the rotation axis of each B-type intermediate gear is the same, the phases of the eccentric shafts on all B-type intermediate gears are the same, the eccentric shaft on each B-type intermediate gear is radially fixed with the swing gear B, and the output gear B is coaxial with the rotation axis of the shell. The above description of spatial position relationship definition is a more rigorous description method for defining direct or indirect connection and contact between parts, and a person skilled in the art can understand the connection relationship between the parts and the overall structure of the technical scheme of the invention according to the above description of spatial position relationship; the shell can be a part or a component consisting of a plurality of parts, and the shell component does not necessarily wrap all the parts completely, and only needs to enable the parts to meet the spatial position relationship and the mechanical connection relationship; the more exact spatial relationship between the radial fixing of the type a and type B intermediate gears relative to the housing is explained by the fact that the axis of rotation of each intermediate gear is fixed at a point on a radial section through the housing, or is limited to a small fixed area on a radial section through the housing because of bearings between the intermediate gears and the housing or the need for oil lubrication to leave clearance for the rotation, the relationship of the housing to all intermediate gears can be understood as the relationship of the planet carrier to the planet gears, the radial fixed relationship between the eccentric shafts of the oscillating gear a and all type a intermediate gears also corresponds to the above description, and the radial fixed relationship between the eccentric shafts of the oscillating gear B and all type B intermediate gears also corresponds to the above description; the spatial position relationship that the eccentric shafts on all the A-type intermediate gears have the same phase can be understood as that the axial line of the eccentric shaft of each A-type intermediate gear of any two A-type intermediate gears and the plane determined by the gear rotation axis always keep parallel, the oscillating gear A revolves synchronously with the rotation of each A-type intermediate gear by taking the shell rotation axis as the axis, the oscillating gear B revolves synchronously with the rotation of each B-type intermediate gear by taking the shell rotation axis as the axis, the torque is input from the shell and is respectively output from the output gear A and the output gear B when the differential operates, the external force is input by any structure and is output by any structure and is not required to be contained in the technical scheme of the differential, but the common gears or the rotation shafts are output usually, and gears or splines with connecting shafts can be processed on the parts or components of the differential.

In the differential mechanism, the shell rotates by external force to drive each A-type intermediate gear and each B-type intermediate gear to revolve around the shell rotation shaft along with the shell, the eccentric shaft on each A-type intermediate gear drives the oscillating gear A to rotate along with the shell, the oscillating gear A drives the output gear A to rotate, the eccentric shaft on each B-type intermediate gear drives the oscillating gear B to rotate along with the shell, the oscillating gear B drives the output gear B to rotate, and the output gear A and the output gear B respectively output and rotate; when the rotating speeds of the output gear A and the output gear B are the same, all parts in the differential are still relative to the shell; when the output loads of the output gear A and the output gear B are different, the output gear A and the output gear B rotate relatively, namely the output gear A and the output gear B respectively rotate relatively in opposite directions with respect to the shell, so that the swinging gear A and the swinging gear B both revolve in opposite directions with respect to the rotation axis of the shell, the revolution of the swinging gear A and the swinging gear B relative to the rotation axis of the shell drives each A-type intermediate gear and each B-type intermediate gear to rotate in opposite directions through eccentric shafts, and is limited by the meshing of the A-type intermediate gear and the B-type intermediate gear, and the output gear A and the output gear B can only rotate relatively in opposite directions with respect to the shell in a fixed rotation speed ratio relation. The above is the principle of the transmission of the rotational motion of the differential or the torque and the differential output; further explaining the realization principle of the limited slip mechanism of the differential mechanism of the invention is as follows: the number of teeth of the output gear A and the swing gear A determines the rotation speed ratio of the swing gear A driven by the rotation of the output gear A relative to the shell to the revolution of the shell by taking the rotation axis of the shell as the axis and the rotation of the output gear A relative to the shell, the revolution speed of the swing gear A is the same as the rotation speed of each A-type intermediate gear, the number of teeth of the output gear B and the swing gear B determines the rotation speed ratio of the swing gear B driven by the rotation of the output gear B relative to the shell to the revolution of the shell by taking the rotation axis of the shell as the axis and the rotation of the output gear B relative to the shell, the revolution speed of the swing gear B is the same as the rotation speed of each B-type intermediate gear, when the two rotation speeds are higher, because of friction and the existence of lubricating oil fluid resistance, the differential internal load when the output gear A and the output gear B rotate relatively can be proportionally amplified according to the relative rotation speed, and meanwhile, the differential internal load also causes the increase of the pressure of meshing surfaces between the output gear A and the oscillating gear A and between the output gear B and the oscillating gear B, the increase of gear pair transmission resistance between the output gear A and the oscillating gear A and between the output gear B and the oscillating gear B is caused, the relative rotation loads of the output gear A and the output gear B are further increased, the increase of the loads balances the external output load difference which causes the rotation speed difference of the output gear A and the output gear B, and the output gear A and the output gear B tend to output at the same speed, namely, the limited slip effect is achieved; whether locking can be achieved specifically at the time of slipping depends on the maximum value of increase in the differential internal load, and it is theoretically possible to achieve relative locking between the output gear a and the output gear B when the differential internal load caused by the relative torque or the relative rotational speed of the output gear a and the output gear B is equal to or greater than the torque input to the case.

The gear pair formed by the swing gear A and the output gear A or the gear pair formed by the swing gear B and the output gear B is a cycloid gear pair. The cycloid gear pair comprises a cycloid pinwheel gear pair, when the cycloid gear pair has less tooth difference, one revolution of two gears relatively rotates corresponds to a gear to revolve around the rotation axis of the other gear for multiple revolutions, so that the resistance in rotation can be amplified, the cycloid gear can select the gear with less teeth, the bearing capacity of the gear is increased in a limited space, in addition, the relationship between the rotation resistance and the torque load of the gear meshing can be adjusted by adjusting the tooth form of the cycloid gear, and the differential with different limited slip capacities can be implemented more favorably.

The differential mechanism is characterized by comprising at least 3A-type intermediate gears and at least 3B-type intermediate gears. More than 3A type intermediate gears and more than 3B type intermediate gears have 3 eccentric shafts to be connected with the swing gear A and the swing gear B, so that the stability of the swing gear revolving around the axis of the rotation shaft of the shell is better facilitated, and the torque load capacity of the shell for driving the swing gear to rotate synchronously with the shell through the rotation of the shell is also better facilitated by the 3 eccentric shafts.

The output gear a and the output gear B are external gears. At the moment, the rotation of the output gear drives the oscillating gear in the gear pair to revolve in the direction opposite to the rotation direction of the output gear, so that the gear transmission resistance between the output gear and the oscillating gear is larger, and the differential lock is more favorably applied to a limited slip differential, or the gear locking realizes the effect of the differential lock due to the fact that the rotation resistance is larger than the input torque after the transmission torque is increased to a certain fixed value.

The output gear a and the output gear B are internal gears. At the moment, the rotation of the output gear drives the oscillating gear in the gear pair to revolve in the same direction as the rotation direction of the output gear, and the gear transmission resistance between the output gear and the oscillating gear is smaller, so that the differential mechanism is more favorable for reducing the resistance and torque loss during differential output.

The A-type intermediate gear and the B-type intermediate gear are both helical gears or worms. The gear pair composed of the bevel gears can generate axial stress when rotating relatively, and the axial stress is beneficial to increasing the friction pressure between the gear and other axial parts, namely increasing the autorotation resistance of the gear wheel; the worm belongs to a gear, a gear pair consisting of the worm and the worm generates axial stress when the worm and the worm rotate relatively, the axial stress increases the friction force between the worm and the worm in the worm gear pair, the rotation resistance of the worm is increased, and meanwhile, the axial stress is favorable for increasing the friction pressure between the worm and other axial parts and also increasing the rotation resistance of the worm; after the resistance of the rotation of the intermediate gear is increased to a certain fixed value, the meshing rotation resistance of the intermediate gear A and the intermediate gear B exceeds the torque causing the relative rotation of the intermediate gear A and the intermediate gear B, and the locking of the differential is realized.

The output gear a, the output gear B, the swing gear a, and the swing gear B are axially fixed with respect to the housing, respectively. The axial fixed spatial relationship with respect to the housing is further explained in that the axial component of the spatial relationship with the housing is kept constant, or a clearance is required to be left between the radial or circumferential movement with respect to the housing and the housing due to the need of a bearing or oil lubrication, and the axial component of the spatial relationship between the rotating part and the housing is limited within a relatively small fixed range, which is also considered to be a fixed form, for example, as shown in the drawings, the housing limits the axial movement of the output gear a and the output gear B away from the housing from both ends, the spatial occupation of other parts in the housing limits the movement of the output gear a and the output gear B toward the center of the housing, and the oscillating gear a and the oscillating gear B have the same principle, and no matter which axial fixed mode is to keep a certain clearance in other directions, which is influenced by the process, but the term of "fixed" in the spatial position description is used to supplement the technical scheme for explaining the technical solution of the present invention for understanding of a person skilled in the art, as long as the technical solution implied by the first paragraph of the content of the present invention and the technical solution, the limitation of the axial movement of the axial limited range, the relative movement of the present invention is still further described, and the condition that the axial limited range can be satisfied.

The type a idler gear and the type B idler gear are axially fixed relative to the housing. The further explanation of the axially fixed spatial relationship with respect to the housing is that the axial component of the spatial relationship with the housing is kept constant, or the axial component of the spatial relationship with the housing is limited to a relatively small fixed range and is also considered to be a fixed form, because the axial fixed form has a certain movable range under the influence of the process, and the term "fixed" is used in the spatial description, which is a term that will supplement the technical solution of the present invention to be understood by those skilled in the art, because the technical solution described in the first paragraph of the present invention is implicitly limited as long as the technical solution described in the first paragraph is satisfied and all the components cannot be infinitely long in the axial direction, the gear must be limited to a certain amount of relative axial movement range to satisfy the connection relationship, and the technical solution described in the first paragraph can be implemented to leave a relatively large axial space for the intermediate gear to satisfy the axial movement of the intermediate gear and to satisfy the axial displacement restriction of the helical gear, and the axial displacement restriction of the worm gear is further increased by the technical solution of the axial displacement restriction.

The shell of the differential also comprises a gear or a spline or a screw hole which is used for being in mechanical connection with the torque input part; the output gear A and the output gear B respectively comprise a gear or a spline which is used for being connected with torque output load mechanics. In the above technical solution of the present invention, the description is directed to describing the structure and mechanical transmission relationship of the differential, and the mechanical connection structure between the differential and the external part is not a part of the structure of the differential to achieve the differential effect, so it is not mentioned in the above technical solutions, but obviously the differential needs to be mechanically connected with the external part as well as all the components without power source when the differential works, and the input of the torque of the differential applied to the equipment provided by the present invention may be that a gear fixed with the housing in the circumferential direction is arranged outside the housing, the gear is engaged with the torque input gear, or the housing is connected with the input shaft through a spline and coaxially and synchronously rotates; the output of the torque can be realized by selecting an output gear A and an output gear B which are respectively connected with the two output shafts through splines and coaxially and synchronously rotate, or by selecting gears which are arranged on the output gear A and the output gear B and are meshed with an external torque load.

The differential mechanism can realize the distribution arrangement of torque output by setting the gear proportion of the A-type intermediate gear and the B-type intermediate gear; the gear ratio of the oscillating gear A and the output gear A and the gear ratio of the oscillating gear B and the output gear B can be used for realizing the distribution setting of the torque output, which is an important improvement advantage of the difference counter of the invention.

The differential mechanism is mainly used for outputting engine power of a vehicle to wheels after passing through the differential mechanism, when the differential mechanism is used as a central differential mechanism, the torque is output to a differential mechanism shell by the differential mechanism, the torque is output to front and rear differential mechanisms by an output gear A and an output gear B respectively, when the differential mechanism is used as a front differential mechanism or a rear differential mechanism, the torque output by the central differential mechanism is output to the differential mechanism shell through a rotating shaft or a gear, and the torque is output to left and right wheels by the output gear A and the output gear B of the differential mechanism respectively.

The load mentioned in the technical scheme of the invention is mechanical load, which refers to a part needing to be driven when rotating or resistance generated by driving other parts to rotate because of the need, and when the load is applied to an automobile, the load refers to resistance born by a differential mechanism needing to drive a rotating axle and wheels and drive the wheels to rotate; torque is sometimes referred to as torque when a rotating part is transmitting rotation, and is used in the description of the invention or described in terms of logic or relationships.

Drawings

Fig. 1 is a schematic structural view (sectional view) of the differential of embodiment 1.

FIG. 2 is an exploded view of the differential components of embodiment 1.

Fig. 3 is a perspective view of the differential of embodiment 1.

Fig. 4 is a schematic structural view (sectional view, hidden screws in the figure) of the differential of embodiment 2.

FIG. 5 is a close-up view of the idler gear of embodiment 2 of the differential (with other parts hidden).

Fig. 6 is a schematic structural view (sectional view) of the differential of embodiment 3.

Fig. 7 is a schematic structural view (sectional view) of the differential according to embodiment 4.

FIG. 8 is a close-up view of the idler gear of embodiment 4 of the differential (with the remaining portion of the housing hidden).

In the figure: 1, a shell; 2, a type intermediate gear; 3, a B-type intermediate gear; 4, a swing gear A;5, a swing gear B;6, an output gear A; and 7, outputting the gear B.

Detailed Description

Embodiment 1, as shown in fig. 1 to 3, an a-type intermediate gear used in this embodiment is 3 identical involute spur gears, a B-type intermediate gear is also 3 identical involute spur gears, the numbers of teeth of the a-type intermediate gear and the B-type intermediate gear are equal, 3 a-type intermediate gears and 3B-type intermediate gears are engaged with each other to form 3 gear pairs, a pair of cycloid inner gear pairs with a tooth difference of 2 is selected for the wobble gear a and the output gear a, wherein the output gear a is an external gear, shafts are machined at both ends of the a-type intermediate gear and have axially extending eccentric shafts machined at one end, shaft holes are respectively inserted into the shaft holes on the end face of the wobble gear a on the 3 a-type intermediate gear, a pair of cycloid inner gear pairs with the same tooth form and number as the wobble gear a and the output gear a on the output gear a, the output gear B is an external gear, shafts are machined at both ends of a spline of the B-type intermediate gear and have axially extending eccentric shafts machined at one end, shaft holes are respectively inserted into shaft holes on the output gear B-type intermediate gear B, and a housing with a central screw is further installed on the housing.

Embodiment 2, as shown in fig. 4 and 5, the a-type intermediate gears selected in this embodiment are 3 identical involute spur gears, the B-type intermediate gears are also 3 identical involute spur gears, the numbers of teeth of the a-type intermediate gears and the B-type intermediate gears are all equal, each a-type intermediate gear is engaged with two adjacent B-type intermediate gears, each B-type intermediate gear is engaged with two adjacent a-type intermediate gears, and 6 intermediate gears form a group, so that the torque bearing capacity of the gears can be better improved, the engagement friction area of the intermediate gears is increased to increase the rotational resistance, the swing gear a and the output gear a use a pair of cycloid internal gear pairs with a tooth difference of 2, wherein the output gear a is an internal gear, the two ends of the a-type intermediate gear are provided with shafts, and one end of the a-type intermediate gear is provided with axially extending eccentric shafts, the eccentric shafts on the 3 a-type intermediate gears are respectively inserted into shaft holes on the end face of the swing gear a, the swing gear B and the output gear B use a pair of gears with shafts, and the output gears with a pair of an external shaft holes, and the shaft holes for mounting the swing gears, and the two shafts, and the output gears are provided with a plurality of output shafts, and the output shafts.

Embodiment 3, as shown in fig. 6, the a-type intermediate gear selected in this embodiment is 3 identical involute straight gears, the B-type intermediate gear is also 3 identical involute straight gears, the numbers of teeth of the a-type intermediate gear and the B-type intermediate gear are all equal, 3 a-type intermediate gears and 3B-type intermediate gears are engaged with each other to form 3 gear pairs, the oscillating gear a and the output gear a select a pair of cycloid inner gear pairs with a tooth difference of 2, wherein the output gear a is an outer gear, both ends of the a-type intermediate gear are processed with shafts and are processed with axially extending eccentric shafts at one end, the eccentric shafts on the 3 a-type intermediate gears are respectively inserted into shaft holes on the end faces of the oscillating gear a, the oscillating gear B and the output gear B select a pair of cycloid inner gear pairs with the same tooth profile and number of teeth as the oscillating gear a and the output gear a, wherein the output gear B is an outer gear, both ends of the B-type intermediate gear are processed with shafts and are processed with axially extending eccentric shafts, the eccentric shafts on both ends of the B-type intermediate gear are respectively inserted into shaft holes on the end faces of the oscillating gear B, the output gear a housing is provided with a coaxial spline shaft, and a housing is connected with a central shaft, and a housing is further connected with a spline shaft, and a housing, and a central shaft is connected with a central shaft, and a housing, and a central shaft is further connected with a spline shaft, and a central shaft is connected with a central shaft, and a housing, as shown in a central shaft, and a housing.

Embodiment 4, as shown in fig. 7 and 8, the a-type intermediate gear used in this embodiment is 3 identical involute spur gears, the B-type intermediate gear is also 3 identical involute spur gears, the numbers of teeth of the a-type intermediate gear and the B-type intermediate gear are equal, 3 a-type intermediate gears and 3B-type intermediate gears are engaged with each other to form 3 gear pairs, three gear pairs are embedded in three notches of the housing corresponding to the outer profiles of the gear pairs, the wobble gear a and the output gear a use a pair of cycloid internal gear pairs with a tooth difference of 2, wherein the output gear a is an external gear, an axially extending eccentric shaft is machined at one end of the a-type intermediate gear, eccentric shafts on the 3 a-type intermediate gears are respectively inserted into shaft holes on the end face of the wobble gear a, the wobble gear B and the output gear B use a pair of cycloid internal gears having the same tooth difference as 2, wherein the output spline gear B is an external gear, an axially extending eccentric shaft is machined at one end of the B-type intermediate gear, eccentric shafts on the 3B-type intermediate gear are respectively inserted into shaft holes on the end face of the wobble gear B, and a central gear is provided with a mounting hole for mounting a central screw for mounting a housing.

Example 5, this implementation considers that when the differential is used as a central differential to output torque to the front and rear shafts in unequal proportion, unequal distribution of torque is achieved by selecting different tooth differences of pairs of cycloid gears, in the example, the selected a-type intermediate gear is 3 identical involute spur gears, the B-type intermediate gear is also 3 identical involute spur gears, the number of teeth of the a-type intermediate gear is equal to that of the B-type intermediate gear, 3 a-type intermediate gears are engaged with 3B-type intermediate gears to form 3 gear pairs, the oscillating gear a and the output gear a are selected from a pair of cycloid internal gear pairs with the tooth difference of 2, wherein the output gear a is an external gear, shafts are processed at two ends of the a-type intermediate gear and an axially extending eccentric shaft is processed at one end of the a-type intermediate gear, the eccentric shafts on the 3 a-type intermediate gears are respectively inserted into shaft holes on the end faces of the oscillating gear a, the oscillating gear B and the output gear B adopt a pair of cycloid internal gear pairs with the tooth difference of 3, wherein the output gear B is an external gear, shafts are processed at two ends of a B-type intermediate gear, an axially extending eccentric shaft is processed at one end of the B-type intermediate gear, the eccentric shafts on the 3B-type intermediate gears are respectively inserted into shaft holes on the end face of the oscillating gear B, shaft holes with splines are arranged at the centers of the output gear A and the output gear B, a shell adopts a component consisting of 4 parts and is assembled and fixed by screws, the shaft holes for connecting the shafts at two ends of the intermediate gear are processed on the shell, and a coaxial spline hole is further processed at the center of the shell for connecting input torque through a shaft (the differential mechanism structure of the embodiment is basically consistent with the embodiment 3, and the only tooth difference between the oscillating gear B and the output gear B is set to be 3).

Claims

1. A differential mechanism is characterized in that: the internal gear pair consists of a shell, a swing gear A and an output gear A, the internal gear pair consists of a swing gear B and an output gear B, at least two A-type intermediate gears and at least two B-type intermediate gears; the radial direction of each A-type intermediate gear is fixed with the shell, the rotation axis of each A-type intermediate gear is parallel to the rotation axis of the shell, each A-type intermediate gear is meshed with at least one B-type intermediate gear, the gear pair gear ratio formed by the A-type intermediate gear and the B-type intermediate gear is the same, each A-type intermediate gear is provided with an eccentric shaft of which the axis is parallel to the rotation axis of each A-type intermediate gear, the distance of the eccentric shaft on each A-type intermediate gear relative to the rotation axis of the gears is the same, the phases of the eccentric shafts on all the A-type intermediate gears are the same, the eccentric shaft on each A-type intermediate gear is radially fixed with the swing gear A, and the output gear A is coaxial with the rotation axis of the shell; the radial direction of each B-type intermediate gear is fixed with the shell, the rotation axis of each B-type intermediate gear is parallel to the rotation axis of the shell, each B-type intermediate gear is meshed with at least one A-type intermediate gear, each B-type intermediate gear is provided with an eccentric shaft, the axis of each B-type intermediate gear is parallel to the rotation axis of each B-type intermediate gear, the distance between the eccentric shaft on each B-type intermediate gear and the rotation axis of each B-type intermediate gear is the same, the phases of the eccentric shafts on all B-type intermediate gears are the same, the eccentric shaft on each B-type intermediate gear is radially fixed with the swing gear B, and the output gear B is coaxial with the rotation axis of the shell; the shell is self-rotated by external force to drive each A-type intermediate gear and each B-type intermediate gear to revolve around a shell rotation shaft along with the shell, an eccentric shaft on each A-type intermediate gear drives a swing gear A to rotate along with the shell, the swing gear A drives an output gear A to rotate, an eccentric shaft on each B-type intermediate gear drives a swing gear B to rotate along with the shell, the swing gear B drives the output gear B to rotate, and the output gear A and the output gear B respectively output and rotate; when the rotating speeds of the output gear A and the output gear B are the same, all parts in the differential are still relative to the shell; when the output loads of the output gear A and the output gear B are different, the output gear A and the output gear B rotate relatively, namely the output gear A and the output gear B respectively rotate relatively in opposite directions with respect to the shell, so that the swinging gear A and the swinging gear B both revolve in opposite directions with respect to the rotation axis of the shell, the revolution of the swinging gear A and the swinging gear B relative to the rotation axis of the shell drives each A-type intermediate gear and each B-type intermediate gear to rotate in opposite directions through eccentric shafts, and is limited by the meshing of the A-type intermediate gear and the B-type intermediate gear, and the output gear A and the output gear B can only rotate relatively in opposite directions with respect to the shell in a fixed rotation speed ratio relation.

2. A differential according to claim 1, wherein: and the gear pair formed by the swing gear A and the output gear A or the gear pair formed by the swing gear B and the output gear B is a cycloid gear pair.

3. A differential according to claim 1, wherein: the differential includes at least 3 type a idler gears and at least 3 type B idler gears.

4. A differential according to claim 1 wherein: the output gear A and the output gear B are external gears.

5. A differential according to claim 1 wherein: the output gear A and the output gear B are internal-tooth gears.

6. A differential according to claim 1 wherein: the A-type intermediate gear and the B-type intermediate gear are both helical gears or worms.

7. A differential according to claim 1 wherein: the output gear A, the output gear B, the swing gear A and the swing gear B are axially fixed relative to the shell respectively.

8. A differential according to claim 1 wherein: the A-type intermediate gear and the B-type intermediate gear are axially fixed relative to the shell.

9. A differential according to claim 1 wherein: the shell of the differential also comprises a gear or a spline or a screw hole which is used for being mechanically connected with the torque input part; the output gear A and the output gear B respectively comprise a gear or a spline which is used for being in mechanical connection with torque output load.