Multi-stage speed reducer with single center distance

Abstract

The utility model provides a single-center-distance multi-stage speed reducer, which belongs to the field of gear transmission, and comprises an input shaft, a middle shaft, an output shaft scheme, an input shaft, a first middle shaft, a second middle shaft, an output shaft scheme, an input shaft, a duplex gear, a differential mechanism, a middle shaft and an output shaft scheme, and the structures of all the schemes are located in the same shell. The axes of the input shaft and the output shaft coincide or are parallel. According to the speed reducer, a main body speed reducer transmission mechanism is formed through a center distance and a transmission combination of an input shaft, a middle shaft and an output shaft combination or an input shaft, a middle shaft, a middle shaft and an output shaft combination or an input shaft, a duplex gear, a middle shaft, an output shaft and a differential mechanism; each transmission shaft stretches across a complete supporting structure (without any cantilever support) of bearings at the two ends, the duplex gear, the output shaft and the differential mechanism are integrated into a coaxial concentric structure, a two-axle-distance multi-stage speed ratio structure is formed, the structure is compact, the space is saved, and the power density is large.

Description

Technical Field

[0001] The utility model belongs to the field of gear transmission, and in particular relates to a multi-stage reducer with a single center distance. Background Art

[0002] In the reducers of new energy vehicles and engineering machinery, the reducers generally have one-stage reduction on two axes and two-stage speed ratio reduction on three axes, which to a certain extent meets the requirements of the reduction transmission of existing new energy vehicles. The reducers with this structure still have room to save reducer space, improve power density and increase reduction ratio within roughly the same wheelbase space (center distance).

[0003] A double intermediate shaft reducer (patent application number: CN202022761118.X) is currently disclosed, including a power input shaft and a power input gear coaxially fixed on the power input shaft; a first intermediate shaft system, including a first intermediate shaft, on which a first gear and a second gear are spaced and coaxially fixed, and the power input gear can mesh with the first gear for transmission, thereby driving the first intermediate shaft to rotate; a second intermediate shaft system, including a second intermediate shaft, on which a third gear and a fourth gear are spaced and coaxially fixed, and the third gear can mesh with the power input gear for transmission, thereby driving the second intermediate shaft to rotate; a power output shaft system, including a power output shaft, on which a power output gear is coaxially fixed, the second gear and the fourth gear can mesh with the power output gear for transmission at the same time, and a differential device is also provided on the power output gear.

[0004] The disclosed scheme realizes multi-stage transmission through double intermediate shafts, but the scheme is a four-shaft transmission, and there is no coaxiality, with four center distances. The more center distances there are, the greater the probability of transmission error will be, the lower the transmission accuracy will be, and the space occupied by the device is also larger, and the power density is lower. Utility Model Content

[0005] The present application provides a single-center-distance multi-stage reducer, which aims to solve the problems of the above-mentioned reducer occupying a large space, and the traditional new energy reducer having large dimensions in specific directions, relatively more center distances (more axes), lower power density, high probability of transmission errors, and low transmission accuracy.

[0006] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0007] A single-center-distance multi-stage reducer comprises an input shaft, an output shaft, a first intermediate shaft and a second intermediate shaft, wherein the input shaft, the output shaft, the first intermediate shaft and the second intermediate shaft are located in the same housing, the input shaft is fixed with a first gear, the first intermediate shaft is fixed with a coaxial second gear and a third gear at intervals, the output shaft is fixed with a fourth gear, the second intermediate shaft is fixed with a coaxial fifth gear and a sixth gear at intervals, and the axis of the input shaft coincides with or is parallel to the axis of the output shaft;

[0008] When the axis of the input shaft coincides with the axis of the output shaft, the first gear meshes with the second gear to realize that the input shaft drives the first intermediate shaft to rotate, the third gear meshes with the fourth gear to realize that the first intermediate shaft drives the output shaft to rotate, and the center distance between the first gear and the second gear is the same as the center distance between the third gear and the fourth gear;

[0009] When the axis of the input shaft is parallel to the axis of the output shaft, the first gear is meshed with the fifth gear to enable the input shaft to drive the second intermediate shaft to rotate, the sixth gear is meshed with the second gear to enable the second intermediate shaft to drive the first intermediate shaft to rotate, the third gear is meshed with the fourth gear to enable the first intermediate shaft to drive the output shaft to rotate, and the center distance between the first gear and the fifth gear, the center distance between the sixth gear and the second gear, and the center distance between the third gear and the fourth gear are all the same.

[0010] Preferably, when the axis of the input shaft coincides with the axis of the output shaft, the second gear is an intermediate shaft gear, the intermediate shaft gear is sleeved with one end of the first intermediate shaft, the fourth gear is the output shaft gear, the output shaft gear is sleeved with one end of the output shaft, the first and second bearings are respectively sleeved on both ends of the first intermediate shaft, the input shaft sleeve is provided with a third bearing, the output shaft sleeve is provided with a fourth bearing, the third bearing corresponds to the fourth bearing, and the first bearing, the second bearing, the third bearing and the fourth bearing are all installed on the housing.

[0011] Preferably, the input shaft or the output shaft is provided with a first cavity, in which a first support is installed, and the first support is sleeved with the other end of the input shaft sleeved with the third bearing or the other end of the output shaft sleeved with the fourth bearing.

[0012] Preferably, a second support is also installed in the first cavity, the second support is located on the inner side of the first support, and the second support is located at the bearing hole of the shell, and the second support is sleeved with the other end of one end of the input shaft sleeved with the third bearing or the other end of one end of the output shaft sleeved with the fourth bearing to further improve the transmission accuracy and rigidity.

[0013] Preferably, when the axis of the input shaft is parallel to the axis of the output shaft, the first intermediate sleeve is provided with a fifth bearing, the input sleeve is provided with a sixth bearing, the fifth bearing and the sixth bearing correspond to each other, the second intermediate sleeve is provided with a seventh bearing, the output sleeve is provided with an eighth bearing, the seventh bearing and the eighth bearing correspond to each other, and the fifth bearing, the sixth bearing, the seventh bearing and the eighth bearing are all installed on the housing.

[0014] Preferably, the input shaft and the output shaft are respectively provided with a second cavity, a third support is installed in the second cavity of the input shaft, the third support is sleeved with the other end of one end of the fifth bearing sleeved on the first intermediate shaft, and a fourth support is installed in the second cavity of the output shaft, the fourth support is sleeved with the other end of one end of the seventh bearing sleeved on the second intermediate shaft.

[0015] Preferably, the axis of the input shaft, the axis of the sixth bearing, the axis of the first intermediate shaft and the axis of the fifth bearing all coincide;

[0016] The axis of the seventh bearing, the axis of the second intermediate shaft, the axis of the output shaft and the axis of the eighth bearing all coincide.

[0017] Preferably, the fifth gear and the sixth gear are transformed into double teeth, a differential is installed in the second cavity of the output shaft, a shaft sleeve is arranged on the outer sleeve of the output shaft housing, the output shaft, the differential and the shaft sleeve are assembled into an integrated shaft, the shaft sleeve corresponds to the double teeth, and a double tooth bearing for radially supporting the double teeth is installed between the shaft sleeve and the double teeth, the eighth bearing is sleeved on one end of the output shaft, and the other end of the output shaft passes through the shaft sleeve, the double tooth bearing and the seventh bearing sleeve, so that the differential transmission and the reduction transmission are coaxial and concentric.

[0018] The utility model has the following beneficial effects:

[0019] (1) The reducer is composed of a center distance and a combination of an input shaft, an intermediate shaft, an output shaft, or a combination of an input shaft, an intermediate shaft, an output shaft, or a transmission combination of an input shaft, a double gear, an intermediate shaft, an output shaft, and a differential to form a main reducer transmission mechanism. Through a single / double input and output hollow shaft structure, each transmission shaft is fully supported by the bearings at both ends (without any cantilever support), and the double gear, output shaft, and differential are integrated into a coaxial concentric structure to form a two-wheelbase multi-speed ratio structure. The bearings are installed in the reducer housing, which has a compact structure, saves space, and has a high power density.

[0020] (2) This transmission structure breaks the convention that conventional reducers require a center distance for one-stage deceleration, and achieves the effect of multi-stage deceleration with a single center distance, reducing the probability of transmission errors and improving transmission accuracy;

[0021] (3) In the case of two-stage reduction, the input shaft and the output shaft can be set to be solid, or one of the shafts can be set to be hollow, and the other shaft can be extended into the hollow through a support to enhance the torque of the gear transmission and the rigidity of the transmission system; in the case of three-stage reduction, the input shaft and the output shaft can be set to be solid, or a structure in which both the input shaft and the output shaft are hollow can be adopted. Compared with conventional reducers, this saves installation space and solves the problem that the transmission part has a cantilever support even if the multi-stage reduction structure has the same wheelbase, thereby improving the rigidity of the transmission system;

[0022] (4) The two-stage or three-stage reducer has a compact structure, a small span in a specific direction, a high power density, and a small installation space and low cost considering the various components of the reducer;

[0023] (5) The three-stage reducer without a differential in this scheme increases the transmission level of the reducer under the single center distance state. Compared with the new energy reducer DHT (without differential), the three-stage reducer can achieve three-stage reduction in single center distance, which increases the reduction ratio range;

[0024] (6) Compared with the reducer of common new energy passenger vehicles, the reducer makes full use of the output shaft space where the differential is located, overcomes the space occupied by the differential, realizes three-speed ratio in a single center distance, overlaps the rotating shaft, and is integrated with the differential assembly to realize a highly integrated hybrid transmission of single-center distance multi-stage reduction transmission and differential transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a cross-sectional view of a two-stage reducer with a single center distance in the utility model;

[0026] Figure 2 It is a cross-sectional view of another two-stage reducer with a single center distance in the utility model;

[0027] Figure 3 It is a cross-sectional view of a three-stage reducer with a single center distance in the utility model;

[0028] Figure 4 It is a structural schematic diagram of the three-stage reducer in the utility model;

[0029] Figure 5 It is a cross-sectional view of a three-stage speed reducer with a differential in the utility model;

[0030] Figure 6 It is a cross-sectional view of a two-stage reducer with a housing in the utility model;

[0031] Figure 7 It is a cross-sectional view of a three-stage reducer with a housing in the utility model.

[0032] Among them, 1-input shaft, 2-output shaft, 3-first intermediate shaft, 4-second intermediate shaft, 5-first bearing, 6-second bearing, 7-third bearing, 8-fourth bearing, 9-intermediate shaft gear, 10-output shaft gear, 11-first support, 12-second support, 13-seventh bearing, 14-eighth bearing, 15-fourth support, 16-fifth bearing, 17-third support, 18-sixth bearing, 19-differential, 20-first gear, 21-second gear, 22-third gear, 23-fourth gear, 24-sixth gear, 25-fifth gear, 26-sleeve, 27-double-tooth bearing. DETAILED DESCRIPTION

[0033] Example 1

[0034] like Figure 3 As shown, a single-center-distance multi-stage reducer comprises an input shaft 1, an output shaft 2, a first intermediate shaft 3 and a second intermediate shaft 4. The input shaft 1, the output shaft 2, the first intermediate shaft 3 and the second intermediate shaft 4 are located in the same housing. The input shaft 1 is fixed with a first gear 20, the first intermediate shaft 3 is fixed with a coaxial second gear 21 and a third gear 22 at intervals, the output shaft 2 is fixed with a fourth gear 23, the second intermediate shaft 4 is fixed with a coaxial fifth gear 25 and a sixth gear 24 at intervals, and the axis of the input shaft 1 coincides with the axis of the output shaft 2.

[0035] like Figure 6 As shown, the input shaft 1, output shaft 2, and first intermediate shaft 3 of the two-stage reducer are all arranged in the same housing; Figure 7 As shown, the input shaft 1, output shaft 2, first intermediate shaft 3 and second intermediate shaft 4 of the three-stage reducer are also arranged in the same housing. The reducer has a compact structure, a small span in a specific direction, a high power density, and a small installation space and low cost due to the comprehensive factors of the various components of the reducer.

[0036] The axis of the input shaft 1 coincides with the axis of the output shaft 2, the first gear 20 meshes with the second gear 21 to enable the input shaft 1 to drive the first intermediate shaft 3 to rotate, the third gear 22 meshes with the fourth gear 23 to enable the first intermediate shaft 3 to drive the output shaft 2 to rotate, and the center distance between the first gear 20 and the second gear 21 is the same as the center distance between the third gear 22 and the fourth gear 23;

[0037] like Figure 1 and 2 As shown, one end of the output shaft 2 is hollow, that is, a first cavity is provided, and one end of the input shaft 1 extends into the first cavity and is fixed for rotation by a first support 11, so that the output shaft 2 and the input shaft 1 form a coaxial structure, and no cantilever support is required, thereby improving the rigidity of the transmission system; this is a two-stage reducer;

[0038] like Figure 1As shown, when the axis of the input shaft 1 coincides with the axis of the output shaft 2, the second gear 21 is the intermediate shaft gear 9, and the intermediate shaft gear 9 is sleeved with one end of the first intermediate shaft 3. The fourth gear 23 is the output shaft gear 10, and the output shaft gear 10 is sleeved with one end of the output shaft 2. The first intermediate shaft 3 is respectively sleeved with a first bearing 5 and a second bearing 6 at both ends. The input shaft 1 is sleeved with a third bearing 7, and the output shaft 2 is sleeved with a fourth bearing 8. The third bearing 7 corresponds to the fourth bearing 8. The first bearing 5, the second bearing 6, the third bearing 7 and the fourth bearing 8 are all installed on the housing.

[0039] The input shaft 1 or the output shaft 2 is provided with a first cavity, in which a first support 11 is installed. The first support 11 is sleeved with the other end of the input shaft 1 sleeved with the third bearing 7 or the other end of the output shaft 2 sleeved with the fourth bearing 8.

[0040] Not only Figure 1 and Figure 2 As shown, the cavity is set on the output shaft 2, and the first cavity can also be set on the input shaft 1. The shaft that is set with the first cavity has the first support 11 set in the first cavity of the shaft to support one end of the other shaft. Thus, the accuracy and rigidity of the transmission system are improved without increasing the cantilever.

[0041] like Figure 1 As shown, this reducer is a two-stage reducer, the second gear 21 of the first intermediate shaft 3 is a sleeve-fixed intermediate shaft gear 9, the fourth gear 23 of the output shaft 2 is a sleeve-fixed output shaft gear 10, and the remaining gears are connected with their corresponding structures to form an integrated gear structure; the center distances between different transmission gears are the same and single, thereby reducing the probability of transmission errors and improving transmission accuracy.

[0042] The power is input through the input shaft 1 , and is transmitted sequentially through the first gear 20 , the intermediate shaft gear 9 , the first intermediate shaft 3 , the third gear 22 , and the output shaft gear 10 , and is then output through the output shaft 2 .

[0043] Example 2

[0044] The difference between this embodiment and embodiment 1 is that: Figure 2 As shown, a second support 12 is also installed in the first cavity. The second support 12 is located on the inner side of the first support 11, and the second support 12 is located at the bearing hole of the shell. The second support 12 is sleeved with the other end of the input shaft 1 on which the third bearing 7 is sleeved or the other end of the output shaft 2 on which the fourth bearing 8 is sleeved, so as to further improve the transmission accuracy and rigidity.

[0045] The position of the second support 12 is close to the bearing hole of the housing (reducer housing) for installing the bearing, which involves the bearing supported by the shaft assembly, and its main supports at both ends are located at the position of the housing bearing, that is, the first bearing 5, the second bearing 6, the third bearing 7 and the fourth bearing 8 are respectively located at the position of the housing for supporting the shaft assembly.

[0046] This reducer is a two-stage reducer. Figure 1 Compared with the two-stage reducer in the conventional system, the stiffness and precision are different. One end of the input shaft 1 extends deeper into the output shaft 2, and the conventional system has higher stiffness.

[0047] Example 3

[0048] Compared with Example 1, the functional components of this embodiment have significant structural and functional changes: Figure 3 and Figure 4 As shown, the input shaft and the input shaft structure are both hollow, which provides space for the bearings and intermediate shafts to improve the accuracy and rigidity of the reducer assembly; both ends of the two intermediate shafts extend into the main support located at the position of the housing bearing; under the premise of the same two shafts [single center distance], one stage of reduction is added to expand the reduction ratio range.

[0049] The axis of the input shaft 1 is parallel to the axis of the output shaft 2, the first gear 20 is meshed with the fifth gear 25 so that the input shaft 1 drives the second intermediate shaft 4 to rotate, the sixth gear 24 is meshed with the second gear 21 so that the second intermediate shaft 4 drives the first intermediate shaft 3 to rotate, the third gear 22 is meshed with the fourth gear 23 so that the first intermediate shaft 3 drives the output shaft 2 to rotate, and the center distance between the first gear 20 and the fifth gear 25, the center distance between the sixth gear 24 and the second gear 21, and the center distance between the third gear 22 and the fourth gear 23 are all the same.

[0050] like Figure 3 As shown, the input shaft 1 and the output shaft 2 are both hollow structures, that is, both are provided with a second cavity, so that one end of the first intermediate shaft 3 extends into the second cavity of the input shaft 1 and is fixed by the third support 17; one end of the second intermediate shaft 4 extends into the second cavity of the output shaft 2 and is fixed by the fourth support 15, forming a two-shaft structure with a compact structure, a small span in a specific direction, a large power density, and good transmission performance. In this case, it is a three-stage reducer.

[0051] The axis of the input shaft 1 is parallel to the axis of the output shaft 2. The first intermediate shaft 3 is provided with a fifth bearing 16. The input shaft 1 is provided with a sixth bearing 18. The fifth bearing 16 corresponds to the sixth bearing 18. The second intermediate shaft 4 is provided with a seventh bearing 13. The output shaft 2 is provided with an eighth bearing 14. The seventh bearing 13 corresponds to the eighth bearing 14. The fifth bearing 16, the sixth bearing 18, the seventh bearing 13 and the eighth bearing 14 are all installed on the housing.

[0052] During the three-stage reduction, the input shaft 1 and the output shaft 2 can also be set to be solid, and are respectively supported by bearings on the housings they are sleeved on, and rotate during transmission.

[0053] The input shaft 1 and the output shaft 2 are respectively provided with a second cavity. A third support 17 is installed in the second cavity of the input shaft 1. The third support 17 is sleeved with the other end of one end of the fifth bearing 16 of the first intermediate shaft 3. A fourth support 15 is installed in the second cavity of the output shaft 2. The fourth support 15 is sleeved with the other end of one end of the seventh bearing 13 of the second intermediate shaft 4.

[0054] The input shaft 1 and the output shaft 2 are both configured as hollow structures so that the bearing end of the intermediate shaft can be extended into the cavity of the reducer housing bearing installation position on the radial outside of the shaft, thereby increasing the stiffness and accuracy of the corresponding shaft assembly and the corresponding gear after installation, and improving the transmission accuracy and stiffness.

[0055] The axis of the input shaft 1 , the axis of the sixth bearing 18 , the axis of the first intermediate shaft 3 , and the axis of the fifth bearing 16 all coincide with each other.

[0056] The axis of the seventh bearing 13 , the axis of the second intermediate shaft 4 , the axis of the output shaft 2 , and the axis of the eighth bearing 14 all coincide.

[0057] The reducer is a three-stage reducer, and the input shaft 1 and the output shaft 2 are both provided with a second cavity, so as to form a coaxial structure with two intermediate shafts respectively. In this embodiment, all gears are connected with their corresponding structures to form an integrated gear structure.

[0058] The power is input from the input shaft 1 , and is output from the output shaft 2 after being transmitted through the first gear 20 , the fifth gear 25 , the second intermediate shaft 4 , the sixth gear 24 , the second gear 21 , the first intermediate shaft 3 , the third gear 22 , and the fourth gear 23 in sequence.

[0059] Example 4

[0060] Compared with Example 3, the functional components of this embodiment have significant structural and functional changes: Figure 5 and Figure 7 As shown, compared with the structure and function of the shaft assembly, the gears for torque transmission and deceleration between the two shafts have been transformed into double teeth, and the primary transmission passive teeth and the secondary transmission active teeth are integrated into double teeth, that is, the fifth gear 25 and the sixth gear 24 have been transformed into double teeth; the radial support of the gear transmission has been transformed into a double-tooth bearing 27 (needle bearing); the output shaft 2 has been transformed into an assembly of the output shaft 2 (differential 19 housing) and the sleeve 26, that is, an integrated shaft, to achieve torque transmission and deceleration between the two shafts.

[0061] The fifth gear 25 and the sixth gear 24 are transformed into double teeth, the differential 19 is installed in the second cavity of the output shaft 2, the output shaft 2 housing is covered with a sleeve 26, the output shaft 2, the differential 19 and the sleeve 26 are assembled into an integrated shaft, the sleeve 26 corresponds to the double teeth, and a double tooth bearing 27 for radially supporting the double teeth is installed between the sleeve 26 and the double teeth. The eighth bearing 14 is sleeved on one end of the output shaft 2, and the other end of the output shaft 2 passes through the sleeve 26, the double tooth bearing 27 and the seventh bearing 13, so that the differential transmission and the reduction transmission are coaxial and concentric.

[0062] The three-stage reducer in this embodiment replaces the structure of the second intermediate shaft 4 and the output shaft 2 with a combination of double teeth, double-tooth bearings 27 and an integrated shaft, and is sleeved on the outside of the housing of the output shaft 2 through a sleeve 26, and is no longer supported in the second cavity of the output shaft 2. The differential 19 is installed in the second cavity of the output shaft 2, and the seventh bearing 13 and the eighth bearing 14 are also respectively sleeved on both ends of the output shaft 2. The differential 19, the output shaft 2, and the sleeve 26 are coaxial and assembled together to form an integrated shaft to integrate the reduction transmission and the differential transmission. Without increasing the center distance, the integration of the reduction and differential transmission is significantly improved.

[0063] The above description is only a specific embodiment of the present invention, but the technical features of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A multi-stage reducer with a single center distance, characterized in that: The invention comprises an input shaft (1), an output shaft (2), a first intermediate shaft (3) and a second intermediate shaft (4); the input shaft (1), the output shaft (2), the first intermediate shaft (3) and the second intermediate shaft (4) are located in the same housing; the input shaft (1) is fixed with a first gear (20); the first intermediate shaft (3) is fixed with a coaxial second gear (21) and a third gear (22) at intervals; the output shaft (2) is fixed with a fourth gear (23); the second intermediate shaft (4) is fixed with a coaxial fifth gear (25) and a sixth gear (24) at intervals; and the axis of the input shaft (1) coincides with or is parallel to the axis of the output shaft (2); When the axis of the input shaft (1) coincides with the axis of the output shaft (2), the first gear (20) meshes with the second gear (21) to enable the input shaft (1) to drive the first intermediate shaft (3) to rotate, the third gear (22) meshes with the fourth gear (23) to enable the first intermediate shaft (3) to drive the output shaft (2) to rotate, and the center distance between the first gear (20) and the second gear (21) is the same as the center distance between the third gear (22) and the fourth gear (23); When the axis of the input shaft (1) is parallel to the axis of the output shaft (2), the first gear (20) meshes with the fifth gear (25) so that the input shaft (1) drives the second intermediate shaft (4) to rotate, the sixth gear (24) meshes with the second gear (21) so that the second intermediate shaft (4) drives the first intermediate shaft (3) to rotate, and the third gear (22) meshes with the fourth gear (23) so that the first intermediate shaft (3) drives the output shaft (2) to rotate. The center distance between the first gear (20) and the fifth gear (25), the center distance between the sixth gear (24) and the second gear (21), and the center distance between the third gear (22) and the fourth gear (23) are all the same.

2. A single-center-distance multi-stage reducer according to claim 1, characterized in that: When the axis of the input shaft (1) coincides with the axis of the output shaft (2), the second gear (21) is an intermediate shaft gear (9), the intermediate shaft gear (9) is sleeved with one end of the first intermediate shaft (3), the fourth gear (23) is an output shaft gear (10), the output shaft gear (10) is sleeved with one end of the output shaft (2), the first and second bearings (5) and (6) are sleeved on both ends of the first intermediate shaft (3), the input shaft (1) is sleeved with a third bearing (7), the output shaft (2) is sleeved with a fourth bearing (8), the third bearing (7) corresponds to the fourth bearing (8), and the first bearing (5), the second bearing (6), the third bearing (7) and the fourth bearing (8) are all mounted on the housing.

3. A single-center-distance multi-stage reducer according to claim 2, characterized in that: The input shaft (1) or the output shaft (2) is provided with a first cavity, in which a first support (11) is installed, and the first support (11) is sleeved with the other end of one end of the input shaft (1) sleeved with the third bearing (7) or the other end of one end of the output shaft (2) sleeved with the fourth bearing (8).

4. A single-center-distance multi-stage reducer according to claim 3, characterized in that: A second support (12) is also installed in the first cavity. The second support (12) is located inside the first support (11). The second support (12) is located at the bearing hole of the housing. The second support (12) is sleeved with the other end of the input shaft (1) sleeved with the third bearing (7) or the other end of the output shaft (2) sleeved with the fourth bearing (8), so as to further improve the transmission accuracy and rigidity.

5. The single-center-distance multi-stage reducer according to claim 1, characterized in that: When the axis of the input shaft (1) is parallel to the axis of the output shaft (2), the first intermediate shaft (3) is sleeved with a fifth bearing (16), the input shaft (1) is sleeved with a sixth bearing (18), the fifth bearing (16) and the sixth bearing (18) correspond to each other, the second intermediate shaft (4) is sleeved with a seventh bearing (13), the output shaft (2) is sleeved with an eighth bearing (14), the seventh bearing (13) and the eighth bearing (14) correspond to each other, and the fifth bearing (16), the sixth bearing (18), the seventh bearing (13) and the eighth bearing (14) are all mounted on the housing.

6. A single-center-distance multi-stage reducer according to claim 5, characterized in that: The input shaft (1) and the output shaft (2) are respectively provided with a second cavity. A third support (17) is installed in the second cavity of the input shaft (1). The third support (17) is sleeved with the other end of one end of the first intermediate shaft (3) sleeved with the fifth bearing (16). A fourth support (15) is installed in the second cavity of the output shaft (2). The fourth support (15) is sleeved with the other end of one end of the second intermediate shaft (4) sleeved with the seventh bearing (13).

7. A single-center-distance multi-stage reducer according to claim 6, characterized in that: The axis of the input shaft (1), the axis of the sixth bearing (18), the axis of the first intermediate shaft (3) and the axis of the fifth bearing (16) all coincide with each other; The axis of the seventh bearing (13), the axis of the second intermediate shaft (4), the axis of the output shaft (2) and the axis of the eighth bearing (14) all coincide with each other.

8. The single-center-distance multi-stage reducer according to claim 7, characterized in that: The fifth gear (25) and the sixth gear (24) are transformed into double-linked gears. A differential (19) is installed in the second cavity of the output shaft (2). A shaft sleeve (26) is disposed on the housing of the output shaft (2). The output shaft (2), the differential (19) and the shaft sleeve (26) are assembled into an integrated shaft. The shaft sleeve (26) corresponds to the double-linked gears. A double-linked gear bearing (27) for radially supporting the double-linked gears is installed between the shaft sleeve (26) and the double-linked gears. The eighth bearing (14) is sleeved on one end of the output shaft (2). The other end of the output shaft (2) passes through the shaft sleeve (26), the double-linked gear bearing (27) and is sleeved with the seventh bearing (13), thereby realizing that the differential transmission and the reduction transmission are coaxial and concentric.

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