Four-motor electromechanical compound transmission for tracked vehicles

Abstract

The present invention relates to a four-motor electromechanical composite transmission device for a tracked vehicle, comprising an engine and two dual-motor drive systems symmetrically arranged on both sides of the engine, the two dual-motor drive systems respectively corresponding to driving the track mechanisms on both sides; two variable-speed planetary gear mechanisms are connected to both ends of the engine, and the two dual-motor drive systems are respectively coupled to the engine through the variable-speed planetary gear mechanisms; a differential planetary gear coupling mechanism is arranged between the two dual-motor drive systems, and the two dual-motor drive systems are coupled to each other through the differential planetary gear coupling mechanism. The present invention adopts a symmetrical structural arrangement as a whole, and the motor, variable-speed planetary gear mechanism, reduction planetary gear, fixed-axis gear reduction mechanism, and two-speed variable-speed planetary gear mechanism are all symmetrically arranged, with simple structure and process, which is conducive to the spatial arrangement of the whole vehicle. At the same time, steering power reflux can be achieved, which can not only reduce energy consumption but also reduce the power level of the motor.

Description

Technical Field

[0001] The invention belongs to the technical field of crawler electric drive, and relates to a four-motor electromechanical composite transmission device for a crawler vehicle. Background Art

[0002] The steering of traditional tracked vehicles is achieved through the speed difference of the tracks on both sides. The transmission system generates the speed difference of the tracks on both sides through the relevant clutch / brake, or hydraulic, electrical and other speed control elements. Unlike wheeled vehicles, the steering of tracked vehicles is power steering, which requires the power of the power system to overcome the steering resistance of the road. When turning on difficult roads or in small radius conditions, a large steering drive torque is required. In order to achieve the steering of tracked vehicles, the inner track needs to provide braking force and the outer track needs to provide driving force. When the vehicle speed is high, the inner track will generate a large steering return power (braking power); if this part of the braking power can be efficiently transmitted to the outer track, it can greatly save the input power of the power source.

[0003] Electrification is the development trend of vehicle power transmission system. Tracked vehicles use motors for driving and steering, which can greatly improve maneuverability. The planetary gear mechanism is used as the coupling mechanism of the transmission system. The design can realize the dual-output hybrid tracked vehicle transmission system, which can not only save the complex steering device and realize independent and precise control of the tracks on both sides, but also realize high-efficiency steering and center steering by controlling the torque of the tracks on both sides.

[0004] The multi-motor drive system can realize flexible power distribution, which has become the development trend of electric drive systems. It can also easily realize the coupling and decoupling of drive and steering, and is the development direction of tracked vehicle electric drive systems. Summary of the invention

[0005] In view of this, the present invention proposes a four-motor electromechanical composite transmission device for tracked vehicles, which includes four drive motors and an engine, and uses a multi-planetary gear transmission mechanism as a power coupling mechanism. By adding a mode switching mechanism to change the power flow in the transmission system, and regulating the motor at the same time, it can achieve precise control of the output power of the track wheels on both sides, and achieve the effect of small radius steering and center steering during high-efficiency travel. Using a planetary gear mechanism as the transmission body can achieve flexible power distribution between four motors and one engine.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A four-motor electromechanical composite transmission device for a tracked vehicle comprises an engine and two dual-motor drive systems symmetrically arranged on both sides of the engine, wherein the two dual-motor drive systems respectively drive the track mechanisms on both sides;

[0008] Two speed-changing planetary gear mechanisms are connected to the two ends of the engine, and the two dual-motor drive systems are respectively power-coupled with the engine through the speed-changing planetary gear mechanisms; a differential planetary gear coupling mechanism is provided between the two dual-motor drive systems, and the two dual-motor drive systems are power-coupled through the differential planetary gear coupling mechanism.

[0009] Furthermore, the dual-motor drive system includes a first motor, a second motor, a reduction planetary gear, a fixed-axis gear reduction mechanism, and a two-speed planetary gear mechanism;

[0010] The first motor, the speed-changing planetary gear mechanism, the fixed-axis gear reduction mechanism, and the speed-reducing planetary gear are sequentially connected in transmission; the second motor, the speed-reducing planetary gear, the differential planetary gear coupling mechanism, and the two-speed speed-changing planetary gear mechanism are sequentially connected in transmission; the two-speed speed-changing planetary gear mechanism is connected in transmission with the crawler mechanism; the first motor is coupled to the engine through the speed-changing planetary gear mechanism, and the second motor is coupled to the first motor and / or the engine through the speed-reducing planetary gear.

[0011] The reduction planetary gears in the two dual-motor drive systems are dynamically coupled via a differential planetary gear coupling mechanism.

[0012] Furthermore, it also includes a motor control module and a power battery module; the first motor and the second motor in the two dual-motor drive systems are both connected to the motor control module and the power battery module;

[0013] The first motor and the second motor are arranged in parallel, and the fixed-axis gear reduction mechanism is arranged between the reduction planetary gear and the speed-changing planetary gear mechanism; the second motors in the two dual-motor drive systems are arranged coaxially.

[0014] Further, the differential planetary gear coupling mechanism includes two differential planetary gear mechanisms, and the planet carriers and the ring gears in the two differential planetary gear mechanisms are cross-connected to each other, that is, the planet carrier of any one differential planetary gear mechanism is fixedly connected to the ring gear of the other differential planetary gear mechanism;

[0015] The reduction planetary gear is connected to the sun gear in the differential planetary gear mechanism; the planet carrier in the differential planetary gear mechanism is connected to a coupling output shaft, and is connected to the two-speed change planetary gear mechanism through the coupling output shaft.

[0016] Further, the two-speed planetary gear mechanism comprises a two-speed sun gear, a two-speed planetary carrier, a two-speed ring gear, a brake, and a synchronizer; the coupling output shaft is connected to the two-speed sun gear, and the two-speed planetary carrier is arranged in the two-speed ring gear through the rotation of the planetary gear; the two-speed planetary carrier is provided with an output member, which is transmission-connected to the crawler mechanism through the output member;

[0017] The synchronizer is provided between the two-speed planetary carrier and the two-speed sun gear, and the synchronizer is switched to realize direct power transmission between the two-speed planetary carrier and the two-speed sun gear; the brake is provided on the two-speed gear ring, and the fixation and free rotation of the two-speed gear ring are realized by the brake switching.

[0018] Furthermore, the reduction planetary gear comprises a reduction sun gear, a reduction planetary carrier, and a reduction ring gear; and is used to reduce speed and increase torque of the first motor and the second motor;

[0019] The fixed-axis gear reduction mechanism is meshed with the reduction planetary carrier for transmission. The reduction planetary carrier is arranged in the reduction gear ring through the rotation of the planetary gear. Brakes are arranged on both sides of the reduction gear ring. The second motor is connected to the reduction sun gear. The reduction planetary carrier is connected to the sun gear in the differential planetary gear coupling mechanism.

[0020] Furthermore, the speed-changing planetary gear mechanism includes a speed-changing sun gear, a speed-changing planetary carrier, and a speed-changing ring gear; the engine is connected to the speed-changing planetary carrier, and the speed-changing planetary carrier is arranged in the speed-changing ring gear through the rotation of the planetary gear, the first motor is connected to the speed-changing sun gear, and the speed-changing ring gear is meshed with the fixed-axis gear reduction mechanism for transmission.

[0021] Furthermore, the fixed-axis gear reduction mechanism includes a fixed-axis reduction gear and an outer gear ring. The outer gear ring is fixed on the speed change gear ring and meshes with the fixed-axis reduction gear for transmission. The fixed-axis reduction gear is also meshed with the reduction planetary gear for transmission.

[0022] Furthermore, the working mode of the four-motor electromechanical composite transmission device for tracked vehicles is controlled accordingly according to the working conditions, and the control method is as follows:

[0023] Parking condition: The first motor and the second motor in the two dual-motor drive systems are both stopped, all brakes and clutches are disengaged, the two-speed planetary gear mechanism is in neutral, the engine is not working, there is no power transmission, and the vehicle is in parking or idling condition;

[0024] Forward straight driving condition: The first motors in the two dual-motor drive systems are both in the power generation state, the engine charges the power battery module through the two first motors, and the two second motors are both in the driving state. When the brake in the two-speed planetary gear mechanism is engaged and the synchronizer is disengaged, the two-speed planetary gear mechanism is in low gear and travels at low speed; when the brake in the two-speed planetary gear mechanism is disengaged and the synchronizer is engaged, the two-speed planetary gear mechanism is in high gear and travels at high speed;

[0025] Reverse driving condition: The first motors in the two dual-motor drive systems are both in the driving state, the two second motors are both in the power generation state, and the engine charges the power battery module through the two second motors. When the brake in the two-speed planetary gear mechanism is engaged and the synchronizer is disengaged, the two-speed planetary gear mechanism is in low gear and drives at low speed; when the brake in the two-speed planetary gear mechanism is disengaged and the synchronizer is engaged, the two-speed planetary gear mechanism is in high gear and drives at high speed;

[0026] Small radius steering condition: the first motor and the second motor in one of the dual-motor drive systems are both in the power generation state, and the first motor and the second motor in the other dual-motor drive system are both in the driving state; the engine charges the battery power module through the first motor and the second motor in the power generation state; when the brake in the two-speed planetary gear mechanism is engaged and the synchronizer is disengaged, the two-speed planetary gear mechanism is in low gear and low-speed steering; when the brake in the two-speed planetary gear mechanism is disengaged and the synchronizer is engaged, the two-speed planetary gear mechanism is in high gear and high-speed steering;

[0027] Center steering condition: the first motor in one dual-motor drive system and the second motor in the other dual-motor drive system are both in the generating state, and the other first motor and the second motor are both in the driving state; the engine charges the battery power module through the first motor and the second motor in the generating state; when the brake in the two-speed planetary gear mechanism is engaged and the synchronizer is disengaged, the two-speed planetary gear mechanism is in low gear and low-speed steering; when the brake in the two-speed planetary gear mechanism is disengaged and the synchronizer is engaged, the two-speed planetary gear mechanism is in high gear and high-speed steering.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention adopts a symmetrical structural arrangement as a whole. The motor, the speed-changing planetary gear mechanism, the reduction planetary gear, the fixed-axis gear reduction mechanism, and the two-speed speed-changing planetary gear mechanism are all arranged symmetrically. The structure and process are simple, which is beneficial to the space arrangement of the whole vehicle.

[0030] 2. The differential planetary gear coupling mechanism in the present invention can realize the steering power reflux, which can not only reduce energy consumption but also reduce the power level of the motor.

[0031] 3. The four motors can be designed with high speed, which is beneficial to improve the power density of the motors; it can realize the power distribution between the four motors and the engine, meet the efficient driving requirements of different loads, and ensure the maneuverability of the vehicle.

[0032] 4. Both output ends have high and low gears, which can realize multi-stage differential output on both sides.

[0033] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 This is a schematic diagram of the principle of the four-motor electromechanical composite transmission device for tracked vehicles of the present invention.

[0036] Figure 2 It is a schematic diagram of the power flow of the four-motor electromechanical composite transmission device for a tracked vehicle of the present invention under straight-line operation conditions.

[0037] Figure 3 It is a schematic diagram of the power flow in the center steering condition of the four-motor electromechanical composite transmission device for tracked vehicles of the present invention.

[0038] Figure 4 It is a schematic diagram of the power flow of the four-motor electromechanical composite transmission device for tracked vehicles of the present invention under small radius turning conditions.

[0039] Figure 5 The figure is a schematic diagram of the power flow of the four-motor electromechanical composite transmission device for tracked vehicles according to the present invention under the reversing condition.

[0040] Figure numerals: 1-motor control module; 2-power battery module; 3-engine; 4a, b-speed gear ring; 5a, b-speed planetary carrier; 6a, b-speed sun gear; 7a, b-motor stator; 8a, b-first motor; 9a, b-outer gear ring; 10a, b-fixed axis reduction gear; 11a, b-reduction planetary carrier; 12a, b-brake; 13a, b-reduction gear ring; 14a, b-reduction sun gear; 15a, b-sun gear; 1 6a, b-planet carrier; 17a, b-ring gear; 18a, b-brake; 19a, b-coupled output shaft; 20a, b-sun gear shaft; 21a, b-second motor; 22a, b-two-speed sun gear; 23a, b-planet gear; 24a, b-two-speed ring gear; 25a, b-synchronizer; 26a, b-brake; 27a, b-output member; 28a, b-planet gear; 29a, b-planet gear; 30a, b-planet gear. DETAILED DESCRIPTION

[0041] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0042] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0043] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0044] See also Figure 1 , which is a four-motor electromechanical composite transmission device for a tracked vehicle, includes an engine 3 and two dual-motor drive systems symmetrically arranged on both sides of the engine 3, the two dual-motor drive systems respectively drive the track mechanisms on both sides; two variable-speed planetary gear mechanisms are connected to both ends of the engine 3, and the two dual-motor drive systems are power-coupled with the engine 3 through the variable-speed planetary gear mechanisms; a differential planetary gear coupling mechanism is arranged between the two dual-motor drive systems, and the two dual-motor drive systems are power-coupled through the differential planetary gear coupling mechanism.

[0045] It also includes a motor control module 1 and a power battery module 2; the first motor and the second motor 21 in the two dual-motor drive systems are connected to the motor control module 1 and the power battery module 2; the first motor and the second motor 21 are arranged in parallel, and the fixed-axis gear reduction mechanism is arranged between the reduction planetary gear and the speed-changing planetary gear mechanism; the second motors 21 in the two dual-motor drive systems are arranged coaxially.

[0046] Since the two dual-motor drive systems are symmetrical in structure, they are distinguished by a and b in the figure. Taking one of them as an example, the detailed structure is introduced:

[0047] The dual-motor drive system includes a first motor 8a, a second motor 21a, a reduction planetary gear, a fixed-axis gear reduction mechanism, and a two-speed variable-speed planetary gear mechanism; the first motor 8a, the variable-speed planetary gear mechanism, the fixed-axis gear reduction mechanism, and the reduction planetary gear are sequentially connected in transmission; the second motor 21a, the reduction planetary gear connection, the differential planetary gear coupling mechanism, and the two-speed variable-speed planetary gear mechanism are sequentially connected in transmission; the two-speed variable-speed planetary gear mechanism is transmission-connected to the track mechanism; the first motor 8a is power-coupled with the engine 3 through the variable-speed planetary gear mechanism, and the second motor 21a is power-coupled with the first motor and / or the engine 3 through the reduction planetary gear; the reduction planetary gears in the two dual-motor drive systems are power-coupled through the differential planetary gear coupling mechanism.

[0048] The four motors have the same structure. Taking the first motor 8a as an example, it includes a motor stator 7a and a motor rotor.

[0049] The two-speed planetary gear mechanism includes a two-speed sun gear 22a, a two-speed planetary carrier, a two-speed ring gear 24a, a brake 26a, and a synchronizer 25a; the coupling output shaft 19a is connected to the two-speed sun gear 22a, and the two-speed planetary carrier is rotatably arranged in the two-speed ring gear 24a through the planetary gear 23a; the two-speed planetary carrier is provided with an output member 27a, and is transmission-connected to the crawler mechanism through the output member 27a;

[0050] A synchronizer 25a is provided between the two-speed planetary carrier 5a and the two-speed sun gear 22a, and the direct power transmission between the two-speed planetary carrier and the two-speed sun gear 22a is achieved by switching the synchronizer 25a; a brake 26a is provided on the two-speed ring gear 24a, and the fixation and free rotation of the two-speed ring gear 24a are achieved by switching the brake 26a.

[0051] The deceleration planetary gear comprises a deceleration sun gear 14a, a deceleration planetary carrier 11a, and a deceleration ring gear 13a; and is used to decelerate and increase torque of the first motor 8a and the second motor 21a;

[0052] The fixed-axis gear reduction mechanism is meshed with the reduction planetary carrier 11a for transmission. The reduction planetary carrier 11a is rotated in the reduction gear ring 13a through the planetary gear 29a. Brakes 12a and 18a are provided on both sides of the reduction gear ring 13a. The second motor 21a is connected to the reduction sun gear 14a through the sun gear shaft 20a. The reduction planetary carrier 11a is connected to the sun gear 15a in the differential planetary gear coupling mechanism.

[0053] The speed-changing planetary gear mechanism includes a speed-changing sun gear 6a, a speed-changing planetary carrier 5a, and a speed-changing ring gear 4a; the engine 3 is connected to the speed-changing planetary carrier 5a, and the speed-changing planetary carrier 5a is rotatably arranged in the speed-changing ring gear 4a through the planetary gear 28a, the first motor is connected to the speed-changing sun gear 6a, and the speed-changing ring gear 4a is meshed with the fixed-axis gear reduction mechanism for transmission.

[0054] The fixed axis gear reduction mechanism comprises a fixed axis reduction gear 10a and an outer gear ring 9a. The outer gear ring 9a is fixedly mounted on the speed change gear ring 4a and meshes with the fixed axis reduction gear 10a for transmission. The fixed axis reduction gear 10a also meshes with the reduction planetary gear for transmission.

[0055] Among them, the differential planetary gear coupling mechanism includes two differential planetary gear mechanisms, in which the planet carrier 16a is rotatably installed in the ring gear 17a through the planetary gear 30a, and the planet carrier 16b is rotatably installed in the ring gear 17b through the planetary gear 30b, wherein the planet carrier 16a is fixedly connected to the ring gear 17b, and the planet carrier 16b is fixedly connected to the ring gear 17a.

[0056] The planet carrier 16a in the reduction planetary gear is connected to the sun gear 15a in the differential planetary gear mechanism; the planet carrier 16a in the differential planetary gear mechanism is also connected to a coupling output shaft 19a, and is connected to the two-speed change sun gear 22a of the two-speed change planetary gear mechanism through the coupling output shaft 19a.

[0057] The engine 3 is placed at the center of the transmission system and can output power to the speed-changing planetary gear mechanisms on both sides. The first motor 8a and the first motor 21a are on the right side of the transmission system, and the second motor 8b and the second motor 21b are on the left side of the transmission system. The five power components are connected to the output components on both sides through a multi-row planetary gear mechanism.

[0058] In the front power chain, the power output from both sides of the engine 3 is coupled with the first motors 8a and b on both sides, and then coupled with the decelerated second motors 21a and b after a fixed reduction ratio, and then transmitted to the power output components 27a and b on both sides through the differential planetary gear coupling mechanism and the two-speed planetary gear mechanism.

[0059] The working mode of the four-motor electromechanical composite transmission device for tracked vehicles is controlled accordingly according to the working conditions. The control method is shown in Table 1:

[0060] Table 1 Working mode of the present invention

[0061]

[0062] Parking condition: The first motor and the second motor in the two dual-motor drive systems stop working, all brakes and clutches are disengaged, the two-speed planetary gear mechanism is in neutral, the engine does not work, there is no power transmission, and the entire vehicle is in a parking or idling condition.

[0063] like Figure 2 As shown, the forward straight driving condition: the engine 3 provides power for the entire system, the first motors 8a and b in the two dual-motor drive systems are both in the power generation state, the engine 3 charges the power battery module 2 through the first motors 8a and b, and the second motors 21a and b are both in the driving state. When driving at low speed, the synchronizers 25a and b are separated, the brakes 26a and b are engaged, and the power is output through the output components 27a and b on both sides. When driving at high speed, the synchronizers 25a and b are engaged, the brakes 26a and b are separated, and the output shafts 19a and b are connected to the output components 27a and b on both sides through the synchronizers 25a and b to directly output power.

[0064] like Figure 3 As shown, the central steering condition: the first motor 8a and the second motor 21b are both in the power generation state, and the first motor 8b and the second motor 21a are both in the driving state; the engine 3 charges the battery power module 2 through the first motor 8a and the second motor 21b. When driving at low speed, the synchronizer 25a is separated, the brake 26a is engaged, the two-speed sun gear 22a is connected to the planetary gear 23a, and the power is output through the output member 27a. When driving at high speed, the synchronizer 25a is engaged, the brake 26a is separated, the coupling output shaft 19a is connected to the output member 27a through the synchronizer 25a, and the power is directly output. The motor control module 1 drives the first motor 8b and the second motor 21a, and the engine 3 reverses the first motor 8a and the second motor 21b.

[0065] like Figure 4 As shown, in the small radius steering condition: the first motor 8a and the second motor 21a are both in the driving state, and the first motor 8b and the second motor 21b are both in the power generation state; the engine 3 charges the battery power module 2 through the first motor 8b and the second motor 21b in the power generation state. When driving at low speed, the synchronizer 25a is disengaged, the brake 26a is engaged, the two-speed sun gear 22a is connected to the planetary gear 23a, and the power is output through the output member 27a. When driving at high speed, the synchronizer 25a is engaged, the brake 26a is disengaged, the coupled output shaft 19a is connected to the output member 27a through the synchronizer 25a, and the power is directly output.

[0066] like Figure 5As shown, in the reverse working condition: the first motor 8a, b are both in the driving state, the second motor 21a, b are both in the power generation state, and the engine 3 charges the power battery module 2 through the second motor 21a, b. When driving at low speed, the synchronizer 25a, b is separated, the brake 26a, b is engaged, the two-speed sun gear 22a, b is connected to the planetary gear 23a, b, and the power is output through the output member 27a, b. When driving at high speed, the synchronizer 25a, b is engaged, the brake 26a, b is separated, the output shaft 19a, b is connected to the output member 27a, b through the synchronizer 25a, b, and the power is directly output.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A four-motor electromechanical composite transmission device for a tracked vehicle, characterized in that: It includes an engine and two dual-motor drive systems symmetrically arranged on both sides of the engine, and the two dual-motor drive systems respectively drive the crawler mechanisms on both sides; Two speed-changing planetary gear mechanisms are connected to the two ends of the engine, and the two dual-motor drive systems are respectively coupled to the engine through the speed-changing planetary gear mechanisms; a differential planetary gear coupling mechanism is provided between the two dual-motor drive systems, and the two dual-motor drive systems are coupled to each other through the differential planetary gear coupling mechanism; The dual-motor drive system includes a first motor, a second motor, a reduction planetary gear, a fixed-axis gear reduction mechanism, and a two-speed planetary gear mechanism; The first motor, the speed-changing planetary gear mechanism, the fixed-axis gear reduction mechanism, and the speed-reducing planetary gear are sequentially connected in transmission; the second motor, the speed-reducing planetary gear, the differential planetary gear coupling mechanism, and the two-speed speed-changing planetary gear mechanism are sequentially connected in transmission; the two-speed speed-changing planetary gear mechanism is connected in transmission with the crawler mechanism; the first motor is coupled to the engine through the speed-changing planetary gear mechanism, and the second motor is coupled to the first motor and / or the engine through the speed-reducing planetary gear. The reduction planetary gears in the two dual-motor drive systems are dynamically coupled via a differential planetary gear coupling mechanism.

2. The four-motor electromechanical compound transmission device for a tracked vehicle according to claim 1, characterized in that: It also includes a motor control module and a power battery module; the first motor and the second motor in the two dual-motor drive systems are both connected to the motor control module and the power battery module; The first motor and the second motor are arranged in parallel, and the fixed-axis gear reduction mechanism is arranged between the reduction planetary gear and the speed-changing planetary gear mechanism; the second motors in the two dual-motor drive systems are arranged coaxially.

3. The four-motor electromechanical composite transmission device for a tracked vehicle according to claim 1, characterized in that: The differential planetary gear coupling mechanism comprises two differential planetary gear mechanisms, wherein the planet carriers and the ring gears in the two differential planetary gear mechanisms are cross-connected to each other, that is, the planet carrier of any one differential planetary gear mechanism is fixedly connected to the ring gear of the other differential planetary gear mechanism; The reduction planetary gear is connected to the sun gear in the differential planetary gear mechanism; the planet carrier in the differential planetary gear mechanism is connected to a coupling output shaft, and is connected to the two-speed change planetary gear mechanism through the coupling output shaft.

4. The four-motor electromechanical compound transmission device for a tracked vehicle according to claim 3, characterized in that: The two-speed planetary gear mechanism comprises a two-speed sun gear, a two-speed planetary carrier, a two-speed ring gear, a brake, and a synchronizer; the coupling output shaft is connected to the two-speed sun gear, and the two-speed planetary carrier is arranged in the two-speed ring gear through the rotation of the planetary gear; the two-speed planetary carrier is provided with an output member, which is transmission-connected to the crawler mechanism through the output member; The synchronizer is provided between the two-speed planetary carrier and the two-speed sun gear, and the synchronizer is switched to realize direct power transmission between the two-speed planetary carrier and the two-speed sun gear; the brake is provided on the two-speed gear ring, and the fixation and free rotation of the two-speed gear ring are realized by the brake switching.

5. The four-motor electromechanical compound transmission device for a tracked vehicle according to claim 1, characterized in that: The deceleration planetary gear comprises a deceleration sun gear, a deceleration planetary carrier, and a deceleration ring gear; and is used to decelerate and increase torque of the first motor and the second motor; The fixed-axis gear reduction mechanism is meshed with the reduction planetary carrier for transmission. The reduction planetary carrier is arranged in the reduction gear ring through the rotation of the planetary gear. Brakes are arranged on both sides of the reduction gear ring. The second motor is connected to the reduction sun gear. The reduction planetary carrier is connected to the sun gear in the differential planetary gear coupling mechanism.

6. The four-motor electromechanical compound transmission device for a tracked vehicle according to claim 1, characterized in that: The speed-changing planetary gear mechanism includes a speed-changing sun gear, a speed-changing planetary carrier, and a speed-changing ring gear; the engine is connected to the speed-changing planetary carrier, and the speed-changing planetary carrier is arranged in the speed-changing ring gear through the rotation of the planetary gear; the first motor is connected to the speed-changing sun gear, and the speed-changing ring gear is meshed with the fixed-axis gear reduction mechanism for transmission.

7. The four-motor electromechanical compound transmission device for a tracked vehicle according to claim 6, characterized in that: The fixed-axis gear reduction mechanism includes a fixed-axis reduction gear and an outer gear ring. The outer gear ring is fixed on the speed change gear ring and meshes with the fixed-axis reduction gear for transmission. The fixed-axis reduction gear is also meshed with the reduction planetary gear for transmission.

8. The four-motor electromechanical compound transmission device for a tracked vehicle according to claim 4, characterized in that: The working mode of the four-motor electromechanical compound transmission device for tracked vehicles is controlled accordingly according to the working conditions, and the control method is as follows: Parking condition: The first motor and the second motor in the two dual-motor drive systems are both stopped, all brakes and clutches are disengaged, the two-speed planetary gear mechanism is in neutral, the engine is not working, there is no power transmission, and the vehicle is in parking or idling condition; Forward straight driving condition: The first motors in the two dual-motor drive systems are both in the power generation state, the engine charges the power battery module through the two first motors, and the two second motors are both in the driving state. When the brake in the two-speed planetary gear mechanism is engaged and the synchronizer is disengaged, the two-speed planetary gear mechanism is in low gear and travels at low speed; when the brake in the two-speed planetary gear mechanism is disengaged and the synchronizer is engaged, the two-speed planetary gear mechanism is in high gear and travels at high speed; Reverse driving condition: The first motors in the two dual-motor drive systems are both in the driving state, the two second motors are both in the power generation state, and the engine charges the power battery module through the two second motors. When the brake in the two-speed planetary gear mechanism is engaged and the synchronizer is disengaged, the two-speed planetary gear mechanism is in low gear and drives at low speed; when the brake in the two-speed planetary gear mechanism is disengaged and the synchronizer is engaged, the two-speed planetary gear mechanism is in high gear and drives at high speed; Small radius steering condition: the first motor and the second motor in one of the dual-motor drive systems are both in the power generation state, and the first motor and the second motor in the other dual-motor drive system are both in the driving state; the engine charges the battery power module through the first motor and the second motor in the power generation state; when the brake in the two-speed planetary gear mechanism is engaged and the synchronizer is disengaged, the two-speed planetary gear mechanism is in low gear and low-speed steering; when the brake in the two-speed planetary gear mechanism is disengaged and the synchronizer is engaged, the two-speed planetary gear mechanism is in high gear and high-speed steering; Center steering condition: the first motor in one dual-motor drive system and the second motor in the other dual-motor drive system are both in the generating state, and the other first motor and the second motor are both in the driving state; the engine charges the battery power module through the first motor and the second motor in the generating state; when the brake in the two-speed planetary gear mechanism is engaged and the synchronizer is disengaged, the two-speed planetary gear mechanism is in low gear and low-speed steering; when the brake in the two-speed planetary gear mechanism is disengaged and the synchronizer is engaged, the two-speed planetary gear mechanism is in high gear and high-speed steering.

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