Double-motor hydraulic mechanical stepless speed change transmission system and method

Abstract

The invention discloses a double-motor hydraulic mechanical stepless speed change transmission system and method, and relates to the technical field of stepless speed change transmission. The output end of an input shaft module is connected with the input end of a power output shaft module and the input end of a hydraulic pump shaft module, and a motor shaft driven gear is meshed with the output end of the input shaft module; the motor shaft driven gear is coaxially connected with the two hydraulic motors, the output end of the hydraulic pump shaft module is connected with the two hydraulic motors, the two hydraulic motors are connected with the input end of the motor shaft sun gear, and the motor shaft sun gear is meshed with the forward planet assembly and the backward planet assembly. The motor shaft driving gear is connected with the forward planet assembly and the backward planet assembly, the forward clutch is connected with the forward planet assembly, the backward clutch is connected with the backward planet assembly, the motor shaft driving gear is further meshed with the output shaft module, and the output end of the output shaft module is used for being connected with a front drive axle and a rear drive axle. The transmission efficiency, the control performance and the working efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of continuously variable transmission, and in particular to a dual-motor hydraulic mechanical continuously variable transmission system and method. Background Art

[0002] At present, domestic wheeled engineering vehicles generally use hydraulic transmission and power shift transmission, which have problems such as low transmission efficiency, low working efficiency, high energy consumption, and difficult to meet emission standards; some engineering vehicles have electric transmission solutions, but the cost is high and the use scenarios are limited, making it difficult to promote them in the market. Since engineering vehicles often need to switch forward and backward when working, the hydraulic mechanical continuously variable transmission system without a clutch requires the pump to reverse the variable and the motor to reverse to achieve forward and backward switching, which has power circulation loss and low reverse transmission efficiency. Summary of the invention

[0003] The purpose of the present invention is to provide a dual-motor hydraulic mechanical continuously variable transmission system and method to solve the problems existing in the above-mentioned prior art and improve transmission efficiency, control performance and work efficiency.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a dual-motor hydraulic mechanical continuously variable transmission system, comprising an input shaft module, a power output shaft module, a hydraulic pump shaft module, a hydraulic motor shaft module and an output shaft module, wherein the input end of the input shaft module is used to connect to an engine, the output end of the input shaft module is connected to the input end of the power output shaft module and the input end of the hydraulic pump shaft module, the output end of the power output shaft module is used for power output, the hydraulic motor shaft module comprises a motor shaft sun gear, a motor shaft driving gear, a motor shaft driven gear, a forward clutch, a reverse clutch, a forward planetary assembly, a reverse planetary assembly and two hydraulic motors, the motor shaft driven gear is connected to the input shaft The output end of the module is meshed, and the motor shaft driven gear is coaxially connected to the two hydraulic motors, the output end of the hydraulic pump shaft module is respectively connected to the two hydraulic motors, and the two hydraulic motors are connected to the input end of the motor shaft sun gear, the motor shaft sun gear is respectively meshed with the forward planetary assembly and the reverse planetary assembly, the motor shaft driving gear is respectively connected to the forward planetary assembly and the reverse planetary assembly, and the forward clutch is connected to the forward planetary assembly, the reverse clutch is connected to the reverse planetary assembly, the motor shaft driving gear is also meshed with the output shaft module, and the output end of the output shaft module is used to connect the front and rear drive axles.

[0006] Preferably, the input shaft module includes an input driving gear, an input internal gear ring, an input planetary carrier, an input planetary gear and an input sun gear, wherein the input driving gear is used to connect the output shaft of the engine, the input driving gear is meshed with the power output shaft module, the input driving gear is also coaxially connected with the input planetary carrier, the input planetary gear is mounted on the input planetary carrier, and the input planetary gear is meshed with the input sun gear and the input internal gear ring.

[0007] Preferably, the power output shaft module comprises a power output passive gear, the power output passive gear is meshed with the input active gear, and the power output passive gear is mounted on the shaft of the power output shaft module.

[0008] Preferably, the hydraulic pump shaft module includes a hydraulic pump driven gear and a hydraulic pump, the hydraulic pump driven gear is meshed with the input internal gear ring, the hydraulic pump driven gear is coaxially connected to the hydraulic pump, and the oil port of the hydraulic pump is connected to the two hydraulic motors through a pipeline.

[0009] Preferably, the two hydraulic motors are respectively a first hydraulic motor and a second hydraulic motor, the two oil ports of the first hydraulic motor are respectively connected to the two oil ports of the hydraulic pump, the two oil ports of the second hydraulic motor are respectively connected to the two oil ports of the hydraulic pump, and the first hydraulic motor, the second hydraulic motor and the motor shaft sun gear are all coaxially connected.

[0010] Preferably, the hydraulic pump is a closed variable displacement piston pump.

[0011] Preferably, the forward planetary assembly includes a forward planetary carrier, a forward planetary wheel and a forward inner ring gear, the forward planetary wheel is mounted on the forward planetary carrier, the reverse planetary assembly includes a reverse planetary carrier, a reverse planetary wheel and a reverse inner ring gear, the reverse planetary wheel is mounted on the reverse planetary carrier, the motor shaft sun gear is meshed with the forward planetary wheel and the reverse planetary wheel, the motor shaft driving gear is connected to the forward planetary carrier and the reverse inner ring gear, the forward clutch is connected to the forward inner ring gear, and the reverse clutch is connected to the reverse planetary carrier.

[0012] Preferably, the output shaft module comprises an output shaft passive gear, and the output shaft passive gear is meshed with the motor shaft driving gear.

[0013] Preferably, the hydraulic motor is a bent-axis variable displacement piston motor.

[0014] The present invention also provides a dual-motor hydraulic mechanical continuously variable transmission method, using the dual-motor hydraulic mechanical continuously variable transmission system described in any one of the above technical solutions, including the following situations:

[0015] When both the forward clutch and the reverse clutch are disengaged, it is neutral gear;

[0016] When the forward clutch is engaged and the reverse clutch is disengaged, it is the forward gear, where:

[0017] When the hydraulic pump is displacing positively, the first hydraulic motor and the second hydraulic motor are rotating positively and both have reached the maximum displacement, it is suitable for heavy-load and low-speed driving, and the power output is realized as low-speed and heavy-load forward movement;

[0018] When the hydraulic pump is displacing positively and the displacement is gradually increasing, the displacement of the first hydraulic motor is gradually decreasing until it becomes zero, and the displacement of the second hydraulic motor is gradually decreasing, or, when the hydraulic pump is displacing positively and the displacement is gradually increasing, the displacement of the second hydraulic motor is gradually decreasing until it becomes zero, and the displacement of the first hydraulic motor is gradually decreasing, the vehicle speed is gradually increased, and the power output is realized as high-speed forward movement;

[0019] When the hydraulic pump is displacing positively and at its maximum displacement, and the first hydraulic motor and the second hydraulic motor are at zero displacement, the vehicle speed reaches its maximum. At this time, the hydraulic transmission power is zero, and the power output is realized as pure mechanical transmission forward;

[0020] When the reverse clutch is engaged and the forward clutch is disengaged, it is the reverse gear, where;

[0021] When the hydraulic pump is displacing positively, the first hydraulic motor and the second hydraulic motor are rotating positively and the displacement reaches the maximum displacement, it is suitable for heavy-load and low-speed driving, and the power output is low-speed and heavy-load backward movement;

[0022] When the hydraulic pump is displacing and the displacement is gradually increasing, the displacement of the second hydraulic motor is gradually decreasing until it becomes zero, and the displacement of the first hydraulic motor is gradually decreasing, or, the displacement of the first hydraulic motor is gradually decreasing until it becomes zero, and the displacement of the second hydraulic motor is gradually decreasing, the vehicle speed is gradually increased, and the power output is achieved as high-speed reverse.

[0023] Compared with the prior art, the present invention has achieved the following technical effects:

[0024] The dual-motor hydraulic mechanical continuously variable transmission system and method provided by the present invention, the output end of the input shaft module is connected to the input end of the power output shaft module and the input end of the hydraulic pump shaft module, the motor shaft driven gear is meshed with the output end of the input shaft module, and the motor shaft driven gear is coaxially connected to the two hydraulic motors, the output end of the hydraulic pump shaft module is respectively connected to the two hydraulic motors, and the two hydraulic motors are both connected to the input end of the motor shaft sun gear. When the forward and reverse vehicle speeds are large, a certain hydraulic motor can be used alternately to extend the life of the gearbox, the motor shaft sun gear is respectively meshed with the forward planetary assembly and the reverse planetary assembly, the motor shaft driving gear is respectively connected to the forward planetary assembly and the reverse planetary assembly, and the forward clutch is connected to the forward planetary assembly, and the reverse clutch is connected to the reverse planetary assembly. When the forward clutch and the reverse clutch are both separated, it is neutral, and when the forward clutch is engaged, the vehicle can be moved forward, and when the reverse clutch is engaged, the vehicle can be moved backward, and the motor shaft driving gear is also meshed with the output shaft module. Through the above design, stepless speed regulation and parking reversing can be achieved according to driving needs, without gear shifting shock, power cycle, good controllability and high operating efficiency; the engine can also be controlled to work at the best power point or the best fuel consumption point according to resistance changes in real time, thereby improving the power or fuel economy of the whole vehicle; at the same time, it has the advantages of both hydraulic transmission and mechanical transmission. On the one hand, it can still achieve a large torque output when the engine speed is low, and has good power. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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 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 these drawings without paying creative work.

[0026] Figure 1 It is a schematic diagram of the dual-motor hydraulic mechanical continuously variable transmission system in Example 1;

[0027] In the figure: 1-input shaft module, 101-input driving gear, 102-input inner ring gear, 103-input planet carrier, 104-input planetary gear, 105-input sun gear, 2-power output shaft module, 201-power output passive gear, 3-hydraulic pump shaft module, 301-hydraulic pump passive gear, 302-hydraulic pump, 4-hydraulic motor shaft module, 401-first hydraulic motor, 402-motor shaft passive gear, 403-motor shaft driving gear, 404-second hydraulic motor, 405-motor shaft sun gear, 406-reverse planet carrier, 407-reverse planetary gear, 408-reverse inner ring gear, 409-forward planet carrier, 410-forward planetary gear, 411-forward inner ring gear, 412-forward clutch, 413-reverse clutch, 5-output shaft module, 501-output shaft passive gear. DETAILED DESCRIPTION

[0028] 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.

[0029] The purpose of the present invention is to provide a dual-motor hydraulic mechanical continuously variable transmission system and method to solve the problems existing in the prior art and improve transmission efficiency, control performance and work efficiency.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Embodiment 1

[0032] like Figure 1As shown, this embodiment provides a dual-motor hydraulic mechanical continuously variable transmission system, which can be used for non-road engineering vehicles, especially for hydraulic mechanical power split continuously variable transmission of engineering vehicles that need to switch forward and backward frequently. The dual-motor hydraulic mechanical continuously variable transmission system includes an input shaft module 1, a power output shaft module 2, a hydraulic pump shaft module 3, a hydraulic motor shaft module 4 and an output shaft module 5. The input end of the input shaft module 1 is used to connect the engine to realize power input, the output end of the input shaft module 1 is connected to the input end of the power output shaft module 2 and the input end of the hydraulic pump shaft module 3, the output end of the power output shaft module 2 is used for power output, the hydraulic motor shaft module 4 includes a motor shaft sun gear 405, a motor shaft driving gear 403, a motor shaft driven gear 402, a forward clutch 412, a reverse clutch 413, a forward planetary assembly, a reverse planetary assembly and two hydraulic motors, the motor shaft driven gear 402 is meshed with the output end of the input shaft module 1, and the motor shaft driven gear 402 is coaxially connected to the two hydraulic motors, and the hydraulic pump The output ends of the shaft module 3 are respectively connected to two hydraulic motors, and the two hydraulic motors are connected to the input end of the motor shaft sun gear 405. When the forward and reverse vehicle speeds are large, a hydraulic motor can be used alternately to extend the life of the gearbox. The motor shaft sun gear 405 is respectively engaged with the forward planetary assembly and the reverse planetary assembly, and the motor shaft driving gear 403 is respectively connected to the forward planetary assembly and the reverse planetary assembly, and the forward clutch 412 is connected to the forward planetary assembly, and the reverse clutch 413 is connected to the reverse planetary assembly. When the forward clutch 412 and the reverse clutch 413 are both separated, it is neutral. When the forward clutch 412 is engaged, the vehicle can be moved forward, and when the reverse clutch 413 is engaged, the vehicle can be moved backward. The motor shaft driving gear 403 is also engaged with the output shaft module 5, and the output end of the output shaft module 5 is used to connect the front and rear drive axles, replacing the existing hydraulic power shift transmission system, realizing stepless speed change through the hydraulic pump 302 and the hydraulic motor, realizing power diversion through the planetary mechanism, and performing hydraulic and mechanical power coupling on the hydraulic motor shaft module 4. Through the above design, this embodiment can realize stepless speed regulation and parking reversing according to driving needs, without gear shifting shock, power cycle, good controllability and high operating efficiency; this embodiment can also control the engine to work at the optimal power point or the optimal fuel consumption point in real time according to the change of resistance, so as to improve the power or fuel economy of the whole vehicle; at the same time, this embodiment has the advantages of both hydraulic transmission and mechanical transmission. On the one hand, it can still achieve a large torque output when the engine speed is low, and the power is good; on the other hand, the transmission efficiency is high, and it is even pure mechanical transmission under certain working conditions, which is energy-saving. The motor does not need to be reversed during reversing, there is no power cycle, and the overall efficiency is high.

[0033] Specifically, the input shaft module 1 includes an input driving gear 101, an input internal gear ring 102, an input planetary carrier 103, an input planetary gear 104 and an input sun gear 105. The input driving gear 101 is used to connect the output shaft of the engine to realize the backward output of the power provided by the engine. The input driving gear 101 is meshed with the power output shaft module 2, so as to facilitate the input of power to the power shaft module to realize power output. The input driving gear 101 is also coaxially connected with the input planetary carrier 103 to realize power input. The input planetary gear 104 is installed on the input planetary carrier 103. The input planetary gear 104 is meshed with the input sun gear 105 and the input internal gear ring 102. When the engine drives the input driving gear 101 to rotate, it also drives the coaxially connected input planetary carrier 103 to rotate. The input planetary carrier 103 drives the input internal gear ring 102 and the input sun gear 105 to rotate. At the same time, the input planetary gear 104 also rotates accordingly to realize power transmission.

[0034] The power output shaft module 2 includes a power output passive gear 201 , which is meshed with the input active gear 101 , and is mounted on the shaft of the power output shaft module 2 to realize power output.

[0035] The hydraulic pump shaft module 3 includes a hydraulic pump passive gear 301 and a hydraulic pump 302. The hydraulic pump passive gear 301 is meshed with the input internal gear ring 102, so that the hydraulic pump passive gear 301 rotates under the drive of the input internal gear ring 102 to achieve power output. The hydraulic pump passive gear 301 is coaxially connected to the hydraulic pump 302, and the oil port of the hydraulic pump 302 is connected to two hydraulic motors through a pipeline.

[0036] The two hydraulic motors are respectively the first hydraulic motor 401 and the second hydraulic motor 404. The two oil ports of the first hydraulic motor 401 are respectively connected to the two oil ports of the hydraulic pump 302, and the two oil ports of the second hydraulic motor 404 are respectively connected to the two oil ports of the hydraulic pump 302. The first hydraulic motor 401, the second hydraulic motor 404 and the motor shaft sun gear 405 are all coaxially connected, thereby realizing power output and power confluence.

[0037] The hydraulic pump 302 is a closed-circuit variable displacement piston pump.

[0038] The forward planetary assembly includes a forward planetary carrier 409, a forward planetary gear 410 and a forward inner gear ring 411, the forward planetary gear 410 is mounted on the forward planetary carrier 409, the backward planetary assembly includes a backward planetary carrier 406, a backward planetary gear 407 and a backward inner gear ring 408, the backward planetary gear 407 is mounted on the backward planetary carrier 406, the motor shaft sun gear 405 is meshed with the forward planetary gear 410 and the backward planetary gear 407, the motor shaft driving gear 403 is connected to the forward planetary carrier 409 and the backward inner gear ring 408, and the forward clutch 412 is connected to the forward inner gear ring 411 is connected, and the reverse clutch 413 is connected to the reverse planetary carrier 406, so that when the vehicle is traveling at a low speed, a large torque can be provided. When the vehicle is traveling at a high speed, a single hydraulic motor can be used to work to meet the vehicle speed and traction requirements. When all clutches are separated, it is in neutral gear. When the forward clutch 412 is engaged, the vehicle can be moved forward. When the reverse clutch 413 is engaged, the vehicle can be moved backward. When the vehicle is traveling at the highest speed, the displacement of the hydraulic pump 302 and the hydraulic motor can be adjusted to achieve pure mechanical transmission, which greatly improves the transmission efficiency of the gearbox and has good energy saving performance.

[0039] The output shaft module 5 includes an output shaft driven gear 501 , and the output shaft driven gear 501 is meshed with the motor shaft driving gear 403 .

[0040] The hydraulic motor is a bent-axis variable displacement piston motor.

[0041] Embodiment 2

[0042] The present invention further provides a dual-motor hydraulic mechanical continuously variable transmission method, using the dual-motor hydraulic mechanical continuously variable transmission system of any one of the first embodiments, including the following situations:

[0043] When the forward clutch 412 and the reverse clutch 413 are both disengaged, the gear is in neutral;

[0044] When the forward clutch 412 is engaged and the reverse clutch 413 is disengaged, it is the forward gear, wherein:

[0045] When the hydraulic pump 302 is displacing positively, the first hydraulic motor 401 and the second hydraulic motor 404 are rotating positively and both have reached the maximum displacement, it is suitable for heavy-load low-speed driving, and the power output is realized as low-speed heavy-load forward movement;

[0046] When the hydraulic pump 302 is displacing positively and the displacement is gradually increasing, the displacement of the first hydraulic motor 401 is gradually decreasing until it becomes zero, and the displacement of the second hydraulic motor 404 is gradually decreasing, or, when the hydraulic pump 302 is displacing positively and the displacement is gradually increasing, the displacement of the second hydraulic motor 404 is gradually decreasing until it becomes zero, and the displacement of the first hydraulic motor 401 is gradually decreasing, the vehicle speed is gradually increased, and the power output is realized as high-speed forward movement;

[0047] When the hydraulic pump 302 is displacing positively and at the maximum, and the first hydraulic motor 401 and the second hydraulic motor 404 are at zero displacement, the vehicle speed reaches the maximum, at which time the hydraulic transmission power is zero, and the power output is realized as pure mechanical transmission forward;

[0048] When the reverse clutch 413 is engaged and the forward clutch 412 is disengaged, it is the reverse gear, wherein;

[0049] When the hydraulic pump 302 is displacing positively, the first hydraulic motor 401 and the second hydraulic motor 404 are rotating positively and the displacement reaches the maximum displacement, it is suitable for heavy-load low-speed driving, and the power output is low-speed heavy-load backward movement;

[0050] When the hydraulic pump 302 is displacing and the displacement is gradually increasing, the displacement of the second hydraulic motor 404 is gradually decreasing until it becomes zero, and the displacement of the first hydraulic motor 401 is gradually decreasing, or, the displacement of the first hydraulic motor 401 is gradually decreasing until it becomes zero, and the displacement of the second hydraulic motor 404 is gradually decreasing, the vehicle speed is gradually increased, and the power output is achieved as high-speed reverse.

[0051] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A dual-motor hydraulic mechanical continuously variable transmission system, characterized in that: It includes an input shaft module, a power output shaft module, a hydraulic pump shaft module, a hydraulic motor shaft module and an output shaft module, wherein the input end of the input shaft module is used to connect to the engine, the output end of the input shaft module is connected to the input end of the power output shaft module and the input end of the hydraulic pump shaft module, the output end of the power output shaft module is used for power output, the hydraulic motor shaft module includes a motor shaft sun gear, a motor shaft driving gear, a motor shaft driven gear, a forward clutch, a reverse clutch, a forward planetary assembly, a reverse planetary assembly and two hydraulic motors, the motor shaft driven gear is meshed with the output end of the input shaft module, and the The motor shaft driven gear is coaxially connected to the two hydraulic motors, the output end of the hydraulic pump shaft module is respectively connected to the two hydraulic motors, the two hydraulic motors are connected to the input end of the motor shaft sun gear, the motor shaft sun gear is respectively engaged with the forward planetary assembly and the reverse planetary assembly, the motor shaft driving gear is respectively connected to the forward planetary assembly and the reverse planetary assembly, and the forward clutch is connected to the forward planetary assembly, the reverse clutch is connected to the reverse planetary assembly, the motor shaft driving gear is also engaged with the output shaft module, and the output end of the output shaft module is used to connect the front and rear drive axles.

2. The dual-motor hydraulic mechanical continuously variable transmission system according to claim 1 is characterized in that: The input shaft module includes an input driving gear, an input internal gear ring, an input planetary carrier, an input planetary gear and an input sun gear. The input driving gear is used to connect the output shaft of the engine. The input driving gear is meshed with the power output shaft module. The input driving gear is also coaxially connected with the input planetary carrier. The input planetary gear is installed on the input planetary carrier. The input planetary gear is meshed with the input sun gear and the input internal gear ring.

3. The dual-motor hydraulic mechanical continuously variable transmission system according to claim 2 is characterized in that: The power output shaft module comprises a power output driven gear, the power output driven gear is meshed with the input driving gear, and the power output driven gear is installed on the shaft of the power output shaft module.

4. The dual-motor hydraulic mechanical continuously variable transmission system according to claim 2, characterized in that: The hydraulic pump shaft module includes a hydraulic pump driven gear and a hydraulic pump. The hydraulic pump driven gear is meshed with the input internal gear ring. The hydraulic pump driven gear is coaxially connected to the hydraulic pump. The oil port of the hydraulic pump is connected to the two hydraulic motors through a pipeline.

5. The dual-motor hydraulic mechanical continuously variable transmission system according to claim 4, characterized in that: The two hydraulic motors are respectively a first hydraulic motor and a second hydraulic motor, the two oil ports of the first hydraulic motor are respectively connected to the two oil ports of the hydraulic pump, the two oil ports of the second hydraulic motor are respectively connected to the two oil ports of the hydraulic pump, and the first hydraulic motor, the second hydraulic motor and the motor shaft sun gear are all coaxially connected.

6. The dual-motor hydraulic mechanical continuously variable transmission system according to claim 4, characterized in that: The hydraulic pump is a closed variable displacement piston pump.

7. The dual-motor hydraulic mechanical continuously variable transmission system according to claim 1, characterized in that: The forward planetary assembly includes a forward planetary carrier, a forward planetary wheel and a forward inner ring gear, and the forward planetary wheel is mounted on the forward planetary carrier. The reverse planetary assembly includes a reverse planetary carrier, a reverse planetary wheel and a reverse inner ring gear, and the reverse planetary wheel is mounted on the reverse planetary carrier. The motor shaft sun gear is meshed with the forward planetary wheel and the reverse planetary wheel. The motor shaft driving gear is connected to the forward planetary carrier and the reverse inner ring gear. The forward clutch is connected to the forward inner ring gear, and the reverse clutch is connected to the reverse planetary carrier.

8. The dual-motor hydraulic mechanical continuously variable transmission system according to claim 1, characterized in that: The output shaft module includes an output shaft driven gear, and the output shaft driven gear is meshed with the motor shaft driving gear.

9. The dual-motor hydraulic mechanical continuously variable transmission system according to claim 1, characterized in that: The hydraulic motor is a bent-axis variable displacement piston motor.

10. A dual-motor hydraulic mechanical continuously variable transmission method, characterized in that: The dual-motor hydraulic mechanical continuously variable transmission system according to any one of claims 1 to 9 includes the following situations: When both the forward clutch and the reverse clutch are disengaged, it is neutral gear; When the forward clutch is engaged and the reverse clutch is disengaged, it is the forward gear, where: When the hydraulic pump is displacing positively, the first hydraulic motor and the second hydraulic motor are rotating positively and both have reached the maximum displacement, it is suitable for heavy-load and low-speed driving, and the power output is realized as low-speed and heavy-load forward movement; When the hydraulic pump is displacing positively and the displacement is gradually increasing, the displacement of the first hydraulic motor is gradually decreasing until it becomes zero, and the displacement of the second hydraulic motor is gradually decreasing, or, when the hydraulic pump is displacing positively and the displacement is gradually increasing, the displacement of the second hydraulic motor is gradually decreasing until it becomes zero, and the displacement of the first hydraulic motor is gradually decreasing, the vehicle speed is gradually increased, and the power output is realized as high-speed forward movement; When the hydraulic pump is displacing positively and at its maximum displacement, and the first hydraulic motor and the second hydraulic motor are at zero displacement, the vehicle speed reaches its maximum. At this time, the hydraulic transmission power is zero, and the power output is realized as pure mechanical transmission forward; When the reverse clutch is engaged and the forward clutch is disengaged, it is the reverse gear, where; When the hydraulic pump is displacing positively, the first hydraulic motor and the second hydraulic motor are rotating positively and the displacement reaches the maximum displacement, it is suitable for heavy-load and low-speed driving, and the power output is low-speed and heavy-load backward movement; When the hydraulic pump is displacing and the displacement is gradually increasing, the displacement of the second hydraulic motor is gradually decreasing until it becomes zero. When the displacement of the first hydraulic motor gradually decreases, or the displacement of the first hydraulic motor gradually decreases until it becomes zero, When the displacement of the second hydraulic motor gradually decreases, the vehicle speed gradually increases, and the power output is achieved as high-speed reverse.

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