Planetary speed change mechanism

Abstract

The invention relates to the technical field of transmission devices, in particular to a planetary speed change mechanism which comprises a front supporting body, a rear supporting body, an input shaft and an output shaft. A main shaft is arranged between the output shaft and the input shaft; a first planet row, a second planet row and a third planet row are installed on the main shaft in series, a pipe body at the left end of a third planet carrier of the third planet row is arranged on the output shaft in a sleeving mode, and an inner hole of the pipe body at the left end of the third planet carrier is connected with the outer cylindrical face of the output shaft through a spline pair. A third brake is fixedly mounted on the rear support body; a second brake is mounted on the right side of the third brake; a first brake is mounted on the right side of the second brake; a first rotary clutch and a second rotary clutch are arranged between the first brake and the front support body; the input shaft is in transmission connection with the first rotating clutch and the second rotating clutch. The first rotating clutch is in transmission connection with the main shaft. The second rotating clutch is in transmission connection with a first sun gear of the first planet row.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission devices, and in particular to a planetary speed change mechanism. Background Art

[0002] The planetary gear transmission is composed of a planetary ring gear, a sun gear, a planetary gear (also known as a satellite gear) and a gear axle. According to the motion relationship between the ring gear, sun gear and planetary gear, the input shaft and the output shaft can be separated from the rigid transmission relationship, the input shaft and the output shaft can be driven in the same or reverse direction, and the transmission ratio of the input and output shafts can be changed. It is widely used in land, sea, aviation and other transportation vehicles.

[0003] In the prior art, a patent application with publication number CN117588530A discloses a planetary transmission, an electric drive axle including a planetary transmission, and an electric vehicle. The transmission unit of the planetary transmission includes an input shaft, a sun gear, a planetary gear set, a planetary carrier one, a planetary carrier two, a ring gear, and an output gear; the clutch unit includes a first clutch and a second clutch.

[0004] However, in the prior art CN117588530A, only two gears, low speed gear and high speed gear, are realized, resulting in a small speed ratio range, which is not conducive to use in various working conditions. Therefore, it is necessary to find a transmission solution with more gears and a simple planetary gear structure. Summary of the invention

[0005] The main purpose of the present invention is to provide a planetary speed change mechanism to solve the above technical problems.

[0006] To achieve the above-mentioned purpose, the present invention proposes a planetary speed change mechanism, comprising a front support body and a rear support body; an input shaft is installed on the front support body; an output shaft is installed at the center hole position of the rear support body; a main shaft is arranged between the output shaft and the input shaft; a first planetary row, a second planetary row and a third planetary row are sequentially installed in series from right to left on the main shaft, a tube body at the left end of the third planetary carrier of the third planetary row is sleeved on the output shaft, and the inner hole of the tube body at the left end of the third planetary carrier is connected to the outer cylindrical surface of the output shaft through a spline pair; a third brake is fixedly installed on the rear support body, and the third brake is used to brake the third planetary row. The third inner gear ring of the planetary row is braked; a second brake is installed on the right side of the third brake, and the second brake is used to brake the second inner gear ring of the second planetary row; a first brake is installed on the right side of the second brake, and the first brake is used to brake the first inner gear ring of the first planetary row; a first rotating clutch and a second rotating clutch are arranged at a position between the first brake and the front support body; the input shaft is respectively connected to the first rotating clutch and the second rotating clutch, and the first rotating clutch is connected to the main shaft; the second rotating clutch is connected to the first sun gear of the first planetary row.

[0007] Preferably, the third planetary gear comprises a third planetary carrier, a third sun gear, a third planetary gear and a third inner gear ring; the third sun gear is mounted on the main shaft; the third planetary gear is mounted on the third planetary carrier; the third planetary gear is meshed with the outer teeth of the third sun gear and with the inner teeth of the third inner gear ring; the second planetary gear comprises a second planetary carrier, a second sun gear, a second planetary gear and a second inner gear ring; the second sun gear is mounted on the main shaft; the second planetary gear is mounted on the second planetary carrier, and the outer teeth at the left end of the second planetary carrier are meshed with the outer teeth of the third planetary gear. The inner teeth of the third inner gear ring are meshed with each other; the second planetary gear is meshed with the outer teeth of the second sun gear, and is meshed with the inner teeth of the second inner gear ring; the first planetary row includes a first planetary carrier, a first sun gear, a first planetary gear and a first inner gear ring; the first sun gear is rotatably mounted on the tube body at the right end of the second planetary carrier, the first planetary gear is mounted on the first planetary carrier, and the outer teeth at the left end of the first planetary carrier are meshed with the inner teeth of the second inner gear ring of the second planetary row; the first planetary gear is meshed with the outer teeth of the first sun gear, and is meshed with the inner teeth of the first inner gear ring.

[0008] Preferably, the third brake includes a third shell and a third brake pad group arranged inside the third shell; the third shell and the rear support body are fastened together by screws; the second brake includes a second shell and a second brake pad group arranged inside the second shell; the first brake includes a first shell and a first brake pad group arranged inside the first shell; the third shell, the second shell and the first shell are fastened together by bolts.

[0009] Preferably, the third brake pad group, the second brake pad group and the first brake pad group respectively include staggered movable plates and static plates, the inner hole of the movable plate is provided with an internal spline, and the outer circumferential surface of the static plate is provided with an external spline; the inner hole surfaces of the third shell, the second shell and the first shell are provided with internal splines; the outer circumferential surfaces of the third inner gear ring, the second inner gear ring and the first inner gear ring are provided with external splines; the movable plate of the third brake pad group is sleeved on the third inner gear ring and matched through splines; the external splines on the static plate of the third brake pad group match with the internal splines of the third shell; the movable plate of the second brake pad group is sleeved on the second inner gear ring and matched through splines; the external splines on the static plate of the second brake pad group match with the internal splines of the second shell; the movable plate of the first brake pad group is sleeved on the first inner gear ring and matched through splines; the external splines on the static plate of the first brake pad group match with the internal splines of the first shell;

[0010] Preferably, the tube at the left end of the third planetary carrier extends into the central hole of the rear support body, and two tapered roller bearings are arranged between the tube at the left end of the third planetary carrier and the central hole of the rear support body.

[0011] Preferably, an output gear is mounted on the output shaft; a countersunk hole is arranged on the right end face of the output gear; a bearing mounting tube is integrally formed on the left end of the rear support body, and a deep groove ball bearing is sleeved on the bearing mounting tube; the outer ring of the deep groove ball bearing is clamped in the countersunk hole on the right end face of the output gear.

[0012] Preferably, plug-in bosses are respectively provided on the two end faces of the main shaft; plug-in countersunk holes are respectively provided on the right end face of the output shaft and the left end face of the input shaft; the plug-in bosses at both ends of the main shaft are respectively inserted into the plug-in countersunk holes of the output shaft and the input shaft, and the outer cylindrical surface of the plug-in boss is slidably matched with the inner hole surface of the plug-in countersunk hole.

[0013] Preferably, a clutch mounting sleeve is mounted on the input shaft, and the left end of the input shaft is connected to the inner hole of the clutch mounting sleeve by a spline pair; the outer cylindrical surface of the left half of the clutch mounting sleeve is provided with an external spline; the first rotary clutch comprises a first clutch housing, and a first friction plate group arranged in the first clutch housing; the first friction plate group comprises an outer friction plate and an inner friction plate arranged alternately, the inner hole of the inner friction plate is provided with an inner spline, and the outer peripheral surface of the outer friction plate is provided with an external spline; the inner hole surfaces of the left and right end tube bodies of the first clutch housing are respectively provided with internal splines; the outer cylindrical surface of the right end of the main shaft is provided with an external spline, and the right end of the main shaft is inserted into the left end tube body of the first clutch housing and connected by a spline pair; the first friction plate group is sleeved on the left half of the clutch mounting sleeve, and the inner spline of the inner friction plate of the first friction plate group matches with the outer spline of the left half of the clutch mounting sleeve, and the outer spline of the outer friction plate of the first friction plate group matches with the inner spline of the right end tube body of the first clutch housing.

[0014] Preferably, the second rotating clutch includes a second clutch inner housing, a second clutch outer housing and a second friction plate group; the second friction plate group also includes outer friction plates and inner friction plates that are arranged alternately; the second friction plate group is sleeved on the outer cylindrical surface of the right section of the second clutch inner housing, and the inner splines of the inner friction plates of the second friction plate group cooperate with the splines on the outer cylindrical surface of the right section of the second clutch inner housing, the outer splines of the outer friction plates of the second friction plate group cooperate with the inner splines of the right end tube body of the second clutch outer housing, the left end of the second clutch outer housing is connected to the first sun gear of the first planetary gear, and the second clutch inner housing is connected to the clutch mounting sleeve by a connecting ring.

[0015] Preferably, a sleeve is installed in the central inner hole of the front support body, and the input shaft can be rotatably installed in the through hole of the sleeve; a first annular groove, a second annular groove and an empty slot are arranged in sequence from left to right on the outer cylindrical surface of the input shaft; a first lubricating oil hole is opened in the center of the right half of the input shaft, and the first lubricating oil hole is connected to the second annular groove; a second lubricating oil hole is opened in the center of the left half of the input shaft, and the second lubricating oil hole is connected to the first annular groove; a third lubricating oil hole is opened in the center of the main shaft, and the third lubricating oil hole is connected to the second lubricating oil hole, a plurality of radial oil outlet holes are arranged on the main shaft, and the radial oil outlet holes are connected to the third lubricating oil hole; an annular oil groove is arranged on the hole wall of the central inner hole of the front support body, an oil filling port is arranged on the front support body, and the oil filling port is connected to the annular oil groove; a radial through hole is opened on the tube wall of the sleeve, and the annular oil groove is connected to the first annular groove through the radial through hole.

[0016] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0017] (1) The planetary speed change mechanism provided in the present invention has three planetary gears, two rotary clutches, and three brakes. Different power transmission paths are formed mainly through the cooperation of different clutches and brakes to achieve different transmission ratios, thereby realizing the multi-gear adjustment function of the speed change structure, which is convenient for use under different working conditions.

[0018] (2) The planetary speed change mechanism provided by the present invention has a reasonable and compact structure, a simple structure, and a small volume, which is conducive to the miniaturization of the planetary speed change mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0020] Figure 1 This is a schematic diagram of the planetary speed change mechanism provided by the present invention.

[0021] Explanation of the accompanying drawings: 1, front support body; 1a, annular oil groove; 1b, oil filling port; 2, rear support body; 2a, bearing mounting tube; 3, input shaft; 3a, first annular groove; 3b, second annular groove; 3c, empty slot; 3d, first lubricating oil hole; 3e, second lubricating oil hole; 4, output shaft; 5, main shaft; 5a, third lubricating oil hole; 5b, radial oil outlet hole; C1, first rotating clutch; C1a, first clutch housing; C2, second rotating clutch; C2a, second clutch inner housing; C2b, second clutch outer housing; C3, first brake; C3a, first housing; C4, second brake; C4a, second housing ; C5, third brake; C5a, third housing; P1, first planetary row; P1a, first planetary carrier; P1b, first sun gear; P1c, first planetary gear; P1d, first inner ring gear; P2, second planetary row; P2a, second planetary carrier; P2b, second sun gear; P2c, second planetary gear; P2d, second inner ring gear; P3, third planetary row; P3a, third planetary carrier; P3b, third sun gear; P3c, third planetary gear; P3d, third inner ring gear; 6, tapered roller bearing; 7, output gear; 8, deep groove ball bearing; 9, clutch mounting sleeve; 10, connecting ring; 11, sleeve; 11a, radial through hole. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0025] Combination Figure 1 As shown, a planetary speed change mechanism includes a front support body 1 and a rear support body 2; an input shaft 3 is installed on the front support body 1; an output shaft 4 is installed at the center hole position of the rear support body 2; a main shaft 5 is arranged between the output shaft 4 and the input shaft 3; a first planetary row P1, a second planetary row P2 and a third planetary row P3 are installed in series from right to left on the main shaft 5, the tube body at the left end of the third planetary carrier P3a of the third planetary row P3 is sleeved on the output shaft 4, and the inner hole of the tube body at the left end of the third planetary carrier P3a is connected to the outer cylindrical surface of the output shaft 4 through a spline pair; a third brake C5 is fixedly installed on the rear support body 2, and the third brake C5 is used to brake the third inner gear ring P3d of the third planetary row P3 Braking; a second brake C4 is installed on the right side of the third brake C5, and the second brake C4 is used to brake the second inner ring P2d of the second planetary row P2; a first brake C3 is installed on the right side of the second brake C4, and the first brake C3 is used to brake the first inner ring P1d of the first planetary row P2; a first rotating clutch C1 and a second rotating clutch C2 are arranged at a position between the first brake C3 and the front support body 1; the input shaft 3 is respectively connected to the first rotating clutch C1 and the second rotating clutch C2, and the first rotating clutch C1 is connected to the main shaft 5; the second rotating clutch C2 is connected to the first sun gear P1b of the first planetary row P1.

[0026] In this embodiment, the third planetary gear P3 includes a third planetary carrier P3a, a third sun gear P3b, a third planetary gear P3c and a third inner ring gear P3d; the third sun gear P3b is mounted on the main shaft 5; the third planetary gear P3c is mounted on the third planetary carrier P3a; the third planetary gear P3c is meshed with the outer teeth of the third sun gear P3b, and is meshed with the inner teeth of the third inner ring gear P3d.

[0027] The second planetary row P2 includes a second planetary carrier P2a, a second sun gear P2b, a second planetary gear P2c and a second inner ring gear P2d; the second sun gear P2b is mounted on the main shaft 5; the second planetary gear P2c is mounted on the second planetary carrier P2a, and the outer teeth at the left end of the second planetary carrier P2a are meshed with the inner teeth of the third inner ring gear P3d of the third planetary row P3; the second planetary gear P2c is meshed with the outer teeth of the second sun gear P2b, and with the inner teeth of the second inner ring gear P2d.

[0028] The first planetary row P1 includes a first planetary carrier P1a, a first sun gear P1b, a first planetary gear P1c and a first inner ring gear P1d; the first sun gear P1b is rotatably mounted on a tube at the right end of the second planetary carrier P2a, the first planetary gear P1c is mounted on the first planetary carrier P1a, and the outer teeth at the left end of the first planetary carrier P1a are meshed with the inner teeth of the second inner ring gear P2d of the second planetary row P2; the first planetary gear P1c is meshed with the outer teeth of the first sun gear P1b, and with the inner teeth of the first inner ring gear P1d.

[0029] The third brake C5 includes a third housing C5a and a third brake pad assembly disposed inside the third housing C5a; the third housing C5a is fastened to the rear support body 2 by screws.

[0030] The second brake C4 includes a second housing C4a and a second brake pad set disposed inside the second housing C4a. The first brake C3 includes a first housing C3a and a first brake pad set disposed inside the first housing C3a. The third housing C5a, the second housing C4a and the first housing C3a are fastened and connected by bolts.

[0031] The third brake pad group, the second brake pad group, and the first brake pad group respectively include staggered movable pads and static pads, the inner hole of the movable pad is provided with an internal spline, and the outer peripheral surface of the static pad is provided with an external spline; the inner hole surface of the third housing C5a, the second housing C4a, and the first housing C3a is provided with an internal spline; the outer peripheral surfaces of the third inner gear ring P3d, the second inner gear ring P2d, and the first inner gear ring P1d are provided with external splines; the movable pad of the third brake pad group is sleeved on the third inner gear ring P3d and Through spline matching; the external spline on the static plate of the third brake pad group matches with the internal spline of the third shell C5a; the dynamic plate of the second brake pad group is sleeved on the second inner gear ring P2d and matched through spline matching; the external spline on the static plate of the second brake pad group matches with the internal spline of the second shell C4a; the dynamic plate of the first brake pad group is sleeved on the first inner gear ring P1d and matched through spline matching; the external spline on the static plate of the first brake pad group matches with the internal spline of the first shell C3a.

[0032] In this embodiment, the tube body at the left end of the third planetary carrier P3a extends into the center hole of the rear support body 2, and two tapered roller bearings 6 are arranged between the tube body at the left end of the third planetary carrier P3a and the center hole of the rear support body 2.

[0033] An output gear 7 is installed on the output shaft 4; a countersunk hole is arranged on the right end face of the output gear 7; a bearing mounting tube 2a is integrally formed at the left end of the rear support body 2, and a deep groove ball bearing 8 is sleeved on the bearing mounting tube 2a; the outer ring of the deep groove ball bearing 8 is clamped in the countersunk hole on the right end face of the output gear 7.

[0034] In order to ensure that the main shaft 5, the output shaft 4 and the input shaft 3 are coaxially arranged, plug-in bosses are respectively arranged on the two end faces of the main shaft 5; plug-in countersunk holes are respectively arranged on the right end face of the output shaft 4 and the left end face of the input shaft 3; the plug-in bosses at both ends of the main shaft 5 are respectively inserted into the plug-in countersunk holes of the output shaft 4 and the input shaft 3, and the outer cylindrical surface of the plug-in boss is slidably matched with the inner hole surface of the plug-in countersunk hole.

[0035] A clutch mounting sleeve 9 is mounted on the input shaft 3, and the left end of the input shaft 3 is connected to the inner hole of the clutch mounting sleeve 9 via a spline pair; the outer cylindrical surface of the left half of the clutch mounting sleeve 9 is provided with an external spline; the first rotary clutch C1 comprises a first clutch housing C1a, and a first friction plate group arranged in the first clutch housing C1a; the first friction plate group comprises an outer friction plate and an inner friction plate arranged alternately, the inner hole of the inner friction plate is provided with an inner spline, and the outer peripheral surface of the outer friction plate is provided with an external spline; the Internal splines are respectively arranged on the inner hole surfaces of the left and right end tube bodies of the first clutch housing C1a; external splines are arranged on the outer cylindrical surface of the right end of the main shaft 5, and the right end of the main shaft 5 is inserted into the left end tube body of the first clutch housing C1a and connected through a spline pair; the first friction plate group is sleeved on the left half of the clutch mounting sleeve 9, and the internal splines of the inner friction plates of the first friction plate group match with the external splines of the left half of the clutch mounting sleeve 9, and the external splines of the outer friction plates of the first friction plate group match with the internal splines of the right end tube body of the first clutch housing C1a.

[0036] In this embodiment, the second rotating clutch C2 includes a second clutch inner housing C2a, a second clutch outer housing C2b and a second friction plate group; the second friction plate group also includes outer friction plates and inner friction plates that are arranged alternately; the second friction plate group is sleeved on the outer cylindrical surface of the right section of the second clutch inner housing C2a, and the inner splines of the inner friction plates of the second friction plate group match the splines on the outer cylindrical surface of the right section of the second clutch inner housing C2a, the outer splines of the outer friction plates of the second friction plate group match the inner splines of the right end tube body of the second clutch outer housing C2b, the left end of the second clutch outer housing C2b is connected to the first sun gear P1b of the first planetary row P1, and the second clutch inner housing C2a is connected to the clutch mounting sleeve 9 through a connecting ring 10.

[0037] A sleeve 11 is installed in the central inner hole of the front support body 1, and the input shaft 3 can be rotatably installed in the through hole of the sleeve 11; a first annular groove 3a, a second annular groove 3b and an empty slot 3c are arranged in sequence from left to right on the outer cylindrical surface of the input shaft 3; a first lubricating oil hole 3d is opened in the center of the right half of the input shaft 3, and the first lubricating oil hole 3d is connected to the second annular groove 3b; a second lubricating oil hole 3e is opened in the center of the left half of the input shaft 3, and the second lubricating oil hole 3e is connected to the first annular groove 3a; at the center of the main shaft 5 A third lubricating oil hole 5a is provided, and the third lubricating oil hole 5a is connected to the second lubricating oil hole 3e. A plurality of radial oil outlet holes 5b are provided on the main shaft 5, and the radial oil outlet holes 5b are connected to the third lubricating oil hole 5a. An annular oil groove 1a is provided on the hole wall of the central inner hole of the front support body 1, and an oil filling port 1b is provided on the front support body 1, and the oil filling port 1b is connected to the annular oil groove 1a. A radial through hole 11a is provided on the tube wall of the sleeve 11, and the annular oil groove 1a is connected to the first annular groove 3a through the radial through hole 11a. By adopting the above structure, the planetary speed change mechanism can be easily lubricated.

[0038] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A planetary speed change mechanism, characterized in that: It comprises a front support body (1) and a rear support body (2); An input shaft (3) is installed on the front support body (1); an output shaft (4) is installed at the center hole of the rear support body (2); and a main shaft (5) is arranged between the output shaft (4) and the input shaft (3); A first planetary row (P1), a second planetary row (P2) and a third planetary row (P3) are sequentially mounted in series from right to left on the main shaft (5); a tube body at the left end of a third planetary carrier (P3a) of the third planetary row (P3) is sleeved on the output shaft (4), and an inner hole of the tube body at the left end of the third planetary carrier (P3a) is connected to an outer cylindrical surface of the output shaft (4) via a spline pair; A third brake (C5) is fixedly mounted on the rear support body (2), and the third brake (C5) is used to brake the third inner gear ring (P3d) of the third planetary gear (P3); A second brake (C4) is installed on the right side of the third brake (C5), and the second brake (C4) is used to brake the second inner gear ring (P2d) of the second planetary gear (P2); A first brake (C3) is installed on the right side of the second brake (C4), and the first brake (C3) is used to brake the first inner gear ring (P1d) of the first planetary gear (P2); A first rotating clutch (C1) and a second rotating clutch (C2) are provided at a position between the first brake (C3) and the front support body (1); The input shaft (3) is respectively connected to the first rotating clutch (C1) and the second rotating clutch (C2); the first rotating clutch (C1) is connected to the main shaft (5); and the second rotating clutch (C2) is connected to the first sun gear (P1b) of the first planetary gear (P1).

2. A planetary speed change mechanism according to claim 1, characterized in that: The third planetary gear (P3) comprises a third planet carrier (P3a), a third sun gear (P3b), a third planetary gear (P3c) and a third inner gear ring (P3d); the third sun gear (P3b) is mounted on the main shaft (5); the third planetary gear (P3c) is mounted on the third planet carrier (P3a); the third planetary gear (P3c) is meshed with the outer teeth of the third sun gear (P3b) and with the inner teeth of the third inner gear ring (P3d); The second planetary gear (P2) comprises a second planetary carrier (P2a), a second sun gear (P2b), a second planetary gear (P2c) and a second inner gear ring (P2d); the second sun gear (P2b) is mounted on the main shaft (5); the second planetary gear (P2c) is mounted on the second planetary carrier (P2a), and the outer teeth at the left end of the second planetary carrier (P2a) are meshed with the inner teeth of the third inner gear ring (P3d) of the third planetary gear (P3); the second planetary gear (P2c) is meshed with the outer teeth of the second sun gear (P2b) and the inner teeth of the second inner gear ring (P2d); The first planetary gear (P1) comprises a first planetary carrier (P1a), a first sun gear (P1b), a first planetary gear (P1c) and a first inner gear ring (P1d); the first sun gear (P1b) is rotatably sleeved on a tube at the right end of the second planetary carrier (P2a); the first planetary gear (P1c) is mounted on the first planetary carrier (P1a), and the outer teeth at the left end of the first planetary carrier (P1a) are meshed with the inner teeth of the second inner gear ring (P2d) of the second planetary gear (P2); the first planetary gear (P1c) is meshed with the outer teeth of the first sun gear (P1b) and with the inner teeth of the first inner gear ring (P1d).

3. A planetary speed change mechanism according to claim 1, characterized in that: The third brake (C5) comprises a third housing (C5a) and a third brake pad group arranged inside the third housing (C5a); the third housing (C5a) is fastened to the rear support body (2) by screws; The second brake (C4) comprises a second housing (C4a) and a second brake pad assembly arranged inside the second housing (C4a); The first brake (C3) comprises a first housing (C3a) and a first brake pad assembly arranged inside the first housing (C3a); The third shell (C5a), the second shell (C4a) and the first shell (C3a) are fastened and connected by bolts.

4. A planetary speed change mechanism as claimed in claim 3, characterized in that: The third brake pad group, the second brake pad group, and the first brake pad group respectively include staggered movable pads and static pads, the inner holes of the movable pads are provided with internal splines, and the outer peripheral surfaces of the static pads are provided with external splines; The inner hole surfaces of the third housing (C5a), the second housing (C4a) and the first housing (C3a) are provided with internal splines; the outer circumferential surfaces of the third inner gear ring (P3d), the second inner gear ring (P2d) and the first inner gear ring (P1d) are provided with external splines; The movable plate of the third brake plate group is sleeved on the third inner gear ring (P3d) and matched through splines; the external splines on the static plate of the third brake plate group are matched with the internal splines of the third housing (C5a); The movable plate of the second brake plate group is sleeved on the second inner gear ring (P2d) and matched through splines; the external splines on the static plate of the second brake plate group are matched with the internal splines of the second housing (C4a); The moving plate of the first brake plate group is sleeved on the first inner gear ring (P1d) and matched through splines; the external splines on the stationary plate of the first brake plate group match with the internal splines of the first housing (C3a).

5. A planetary speed change mechanism according to claim 1, characterized in that: The tube at the left end of the third planetary carrier (P3a) extends into the center hole of the rear support body (2), and two tapered roller bearings (6) are arranged between the tube at the left end of the third planetary carrier (P3a) and the center hole of the rear support body (2).

6. A planetary speed change mechanism according to claim 1, characterized in that: An output gear (7) is mounted on the output shaft (4); a countersunk hole is arranged on the right end face of the output gear (7); a bearing mounting tube (2a) is integrally formed at the left end of the rear support body (2), and a deep groove ball bearing (8) is sleeved on the bearing mounting tube (2a); the outer ring of the deep groove ball bearing (8) is clamped in the countersunk hole on the right end face of the output gear (7).

7. A planetary speed change mechanism according to claim 1, characterized in that: The two end surfaces of the main shaft (5) are respectively provided with plug-in bosses; the right end surface of the output shaft (4) and the left end surface of the input shaft (3) are respectively provided with plug-in countersunk holes; the plug-in bosses at the two ends of the main shaft (5) are respectively inserted into the plug-in countersunk holes of the output shaft (4) and the input shaft (3), and the outer cylindrical surface of the plug-in boss is slidably matched with the inner hole surface of the plug-in countersunk hole.

8. A planetary speed change mechanism according to claim 1, characterized in that: A clutch mounting sleeve (9) is mounted on the input shaft (3), and the left end of the input shaft (3) is connected to the inner hole of the clutch mounting sleeve (9) via a spline pair; an outer cylindrical surface of the left half of the clutch mounting sleeve (9) is provided with an external spline; The first rotary clutch (C1) comprises a first clutch housing (C1a) and a first friction plate group arranged in the first clutch housing (C1a); the first friction plate group comprises outer friction plates and inner friction plates arranged alternately, the inner hole of the inner friction plate is provided with an inner spline, and the outer peripheral surface of the outer friction plate is provided with an outer spline; Internal splines are respectively arranged on the inner hole surfaces of the left and right end tube bodies of the first clutch housing (C1a); an external spline is arranged on the outer cylindrical surface of the right end of the main shaft (5); the right end of the main shaft (5) is inserted into the left end tube body of the first clutch housing (C1a) and connected through a spline pair; The first friction plate group is sleeved on the left half of the clutch mounting sleeve (9), and the inner splines of the inner friction plates of the first friction plate group match the outer splines of the left half of the clutch mounting sleeve (9), and the outer splines of the outer friction plates of the first friction plate group match the inner splines of the right end tube of the first clutch housing (C1a).

9. A planetary speed change mechanism according to claim 8, characterized in that: The second rotary clutch (C2) comprises a second clutch inner housing (C2a), a second clutch outer housing (C2b) and a second friction plate group; the second friction plate group also comprises outer friction plates and inner friction plates arranged alternately; The second friction plate group is sleeved on the outer cylindrical surface of the right section of the second clutch inner housing (C2a), and the inner splines of the inner friction plates of the second friction plate group match the splines on the outer cylindrical surface of the right section of the second clutch inner housing (C2a), and the outer splines of the outer friction plates of the second friction plate group match the inner splines of the right end tube body of the second clutch outer housing (C2b), the left end of the second clutch outer housing (C2b) is connected to the first sun gear (P1b) of the first planetary gear (P1), and the second clutch inner housing (C2a) is connected to the clutch mounting sleeve (9) via a connecting ring (10).

10. A planetary speed change mechanism according to claim 1, characterized in that: A sleeve (11) is installed in the central inner hole of the front support body (1), and the input shaft (3) is rotatably installed in the through hole of the sleeve (11); A first annular groove (3a), a second annular groove (3b) and an empty groove (3c) are sequentially arranged on the outer cylindrical surface of the input shaft (3) from left to right; A first lubricating oil hole (3d) is provided at the center of the right half of the input shaft (3), and the first lubricating oil hole (3d) is connected to the second annular groove (3b); A second lubricating oil hole (3e) is provided at the center of the left half of the input shaft (3), and the second lubricating oil hole (3e) is connected to the first annular groove (3a); A third lubricating oil hole (5a) is provided at the center of the main shaft (5), the third lubricating oil hole (5a) is connected to the second lubricating oil hole (3e), a plurality of radial oil outlet holes (5b) are provided on the main shaft (5), and the radial oil outlet holes (5b) are connected to the third lubricating oil hole (5a); An annular oil groove (1a) is provided on the hole wall of the central inner hole of the front support body (1), and an oil filling port (1b) is provided on the front support body (1), and the oil filling port (1b) is connected to the annular oil groove (1a); a radial through hole (11a) is opened on the tube wall of the sleeve (11), and the annular oil groove (1a) is connected to the first annular groove (3a) through the radial through hole (11a).

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