A high-torque continuously variable transmission drive system transmission efficiency calculation method

Abstract

The application provides a high-torque continuously variable transmission drive system transmission efficiency calculation method, and belongs to the technical field of drive systems. The application constructs an equivalent model of the drive system, analyzes the transmission chain of the equivalent model under low-speed gear and high-speed gear two working sections, calculates the overall transmission efficiency of the drive system through the transmission ratio from the output shaft to the input shaft, so that the transmission efficiency of the high-torque continuously variable transmission drive system can be directly quantitatively calculated, and a theoretical guidance basis is provided for the actual application of the drive system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of transmission system, and particularly relates to a high-torque continuously variable transmission (HCVT) transmission system transmission efficiency calculation method. BACKGROUND

[0002] The HCVT (high-torque continuously variable transmission) transmission system adopts a composite transmission form of mechanical transmission and hydraulic transmission. In the transmission process, the transmission shaft is rigidly connected, and the transmission efficiency loss does not need to be considered. The components that need to be considered for efficiency loss include: gear shifting gears, variable pump-quantitative motor and planetary gear train. The gear shifting gears are generally reduction or variable speed devices composed of gear fitting pairs. The efficiency of the hydraulic closed loop composed of the variable pump-quantitative motor mainly changes with the changes of the rotational speed, oil pressure and displacement. The transmission efficiency of the planetary gear transmission greatly varies according to the different structure types, changes of the transmission ratio and changes of the driving and driven parts, and the transmission efficiency change range can be from 0.98 to 0, or even a self-locking phenomenon occurs. Therefore, in the HCVT transmission system, the transmission efficiency generally has great fluctuations, and the empirical value cannot be directly used for guidance and determination.

[0003] Therefore, it is necessary to provide a high-torque continuously variable transmission transmission system transmission efficiency calculation method to solve the problems mentioned in the background. SUMMARY

[0004] The application provides a high-torque continuously variable transmission transmission system transmission efficiency calculation method. The equivalent model of the transmission system is constructed, the transmission chain of the equivalent model is analyzed under the low-speed gear and high-speed gear two working sections, the transmission ratio is calculated to determine the overall transmission efficiency of the transmission system, so that the transmission efficiency of the HCVT can be directly quantitatively calculated, and the theoretical guidance basis is provided for the actual application of the transmission system.

[0005] To solve the above technical problems, the technical scheme of the application is as follows:

[0006] A high-torque continuously variable transmission transmission system transmission efficiency calculation method, comprising the following steps:

[0007] Step S1, constructing an equivalent model of a transmission system, the equivalent model comprising an input shaft, an output shaft, a first planetary row and a second planetary row, an input transmission shaft and an output transmission shaft; the input transmission shaft comprising a first input transmission and a second input transmission shaft, both of which are connected to the input shaft; the output transmission shaft comprising a first output transmission shaft and a second output transmission shaft, both of which are connected to the output shaft;

[0008] The first planetary gear train includes a first sun gear, a first planet gear, a first planet carrier and a first ring gear; the second planetary gear train includes a second sun gear, a second planet gear, a second planet carrier and a second ring gear; the first sun gear and the second sun gear are both mounted on the first input shaft; the first planet carrier is mounted on the second input shaft, and the second ring gear is fixed with the first planet carrier through a connecting piece;

[0009] The first input shaft is provided with a hydraulic transmission system for converting the input power of the input shaft into hydraulic power for transmission;

[0010] Step S2, based on the equivalent model, a transmission chain is constructed, wherein:

[0011] In the low-speed gear working section, the input power of the input shaft is divided into two branches, one branch is input to the first sun gear through the first input shaft; the other branch is input to the first planet carrier through the second input shaft; after power confluence, the power is output to the first output shaft through the first ring gear, and finally output through the output shaft;

[0012] In the high-speed gear working section, the input power of the input shaft is divided into two branches, one branch is input to the second sun gear through the first input shaft; the other branch is input to the first planet carrier through the second input shaft, and then transmitted to the second ring gear; after power confluence, the power is output to the second output shaft through the second planet carrier, and finally output through the output shaft;

[0013] Step S3, the second input shaft is fixed, the first input shaft is operated, the first transmission ratio of the output shaft to the input shaft is calculated; the first input shaft is fixed, the second input shaft is operated, the second transmission ratio of the output shaft to the input shaft is calculated; the first transmission ratio and the second transmission ratio are summed up, respectively, to obtain the transmission ratio of the output shaft to the input shaft in two working sections;

[0014] Step S4: according to the meshing power method, the transmission efficiency of the transmission system is calculated according to the transmission ratio.

[0015] Preferably, the calculation process of the transmission ratio in the low-speed gear working section is:

[0016]

[0017]

[0018]

[0019] In the formula, This indicates the transmission ratio from the output shaft to the input shaft in the low-speed operating range; This indicates the transmission ratio from the output shaft to the input shaft when the second input transmission shaft is fixed. This indicates the transmission ratio from the output shaft to the input shaft when the first input transmission shaft is fixed. This indicates the transmission ratio from the output shaft to the first input shaft when the second input drive shaft is fixed; i bI This indicates the transmission ratio from the first input drive shaft to the input shaft; This indicates the transmission ratio from the output shaft to the second input shaft when the first input drive shaft is fixed; i aI This indicates the transmission ratio from the second input drive shaft to the input shaft.

[0020] Preferably, the transmission efficiency η in the low-speed gear operating range HM1 Represented as:

[0021]

[0022] In the formula, This indicates the transmission ratio from the input shaft to the output shaft in the low-speed operating range; ψ x ψ represents the loss coefficient of power transmission in the drive train when the first planetary carrier is fixed; aI ψ represents the loss coefficient of the second input drive shaft; bI η represents the loss coefficient of the first input drive shaft; aI Indicates the transmission efficiency of the second input drive shaft; η bI η1 represents the transmission efficiency of the first input drive shaft; η1 represents the transmission efficiency of the lower gear shift gear in the low-speed working section.

[0023] Preferably, the calculation process for the transmission ratio in the high-speed gear operating section is as follows:

[0024]

[0025]

[0026]

[0027] In the formula, This indicates the transmission ratio from the output shaft to the input shaft in the high-speed gear operating range; This indicates the transmission ratio from the output shaft to the input shaft when the first output drive shaft is fixed. This indicates the transmission ratio from the output shaft to the input shaft when the second output drive shaft is fixed. represents the transmission ratio of the output shaft to the first output transmission shaft when the first output transmission shaft is fixed;i eI represents the transmission ratio of the second output transmission shaft to the input shaft; represents the transmission ratio of the output shaft to the first output transmission shaft when the second output transmission shaft is fixed;i dI represents the transmission ratio of the first output transmission shaft to the input shaft.

[0028] Preferably, the transmission efficiency η of the low-speed gear working section HM2 represents:

[0029]

[0030] wherein, represents the transmission ratio of the input shaft to the output shaft in the high-speed gear working section; ψ y represents the loss coefficient of the power transmission of the transmission chain when the second planetary carrier is fixed; ψ dI represents the loss coefficient of the first output transmission shaft; ψ eI represents the loss coefficient of the second output transmission shaft; η dI represents the transmission efficiency of the first output transmission shaft; η eI represents the transmission efficiency of the second output transmission shaft; η2 represents the transmission efficiency of the gear in the low-speed gear working section.

[0031] Preferably, the input shaft and the first input transmission shaft are connected through gear pair I1; the input shaft and the second input transmission shaft are connected through gear pair I2; the first inner ring gear and the first output transmission shaft are connected through gear pair I3; the second planetary carrier and the second output transmission shaft are connected through gear pair I4.

[0032] Preferably, the output transmission shaft further comprises a third output transmission shaft, and the first input transmission shaft and the third output transmission shaft are connected through gear pair I5.

[0033] Preferably, a wet clutch C1 is arranged on the first output shaft; a wet clutch C2 is arranged on the second output shaft; and a wet clutch C3 is arranged on the third output shaft.

[0034] Preferably, the hydraulic transmission system comprises a variable pump and a constant motor, the constant motor is used to drive the variable pump to operate, and the on-off and flow rate of the variable pump are controlled.

[0035] The application has the following beneficial effects:

[0036] (1) An equivalent model of a high-torque continuously variable transmission is provided, which can well simulate the transmission chain of the composite transmission form of mechanical transmission and hydraulic transmission under different working sections, and facilitates intuitive analysis of the power transmission process.

[0037] (2) By using the equivalent model of the transmission system, the transmission chain of the equivalent model is analyzed in two working sections: low speed and high speed. The overall transmission efficiency of the transmission system is determined by calculating the transmission ratio, so that the transmission efficiency of HCVT can be directly quantified and calculated, providing theoretical guidance for the practical application of the transmission system. Attached Figure Description

[0038] Figure 1 A schematic diagram showing the equivalent model of the transmission system;

[0039] Figure 2 A schematic diagram showing the transmission chain in the low-speed gear operating segment;

[0040] Figure 3 A schematic diagram showing the transmission chain in the high-speed gear operating section. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] Please see Figures 1-3 This application provides a method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system, comprising the following steps:

[0043] Step S1: Construct an equivalent model of the transmission system. The equivalent model includes an input shaft I, an output shaft C, a first planetary gear set K1 and a second planetary gear set K2, an input drive shaft, and an output drive shaft. The input drive shaft includes a first input drive shaft A1 and a second input drive shaft A2, both connected to the input shaft I. The output drive shaft includes a first output drive shaft B1, a second output drive shaft B2, and a third output drive shaft B3, all connected to the output shaft C.

[0044] The first planetary gear set K1 includes a first sun gear, a first planet gear, a first planet carrier, and a first internal gear ring. The second planetary gear set includes a second sun gear, a second planet gear, a second planet carrier, and a second internal gear ring.

[0045] Both the first sun gear and the second sun gear are mounted on the first input drive shaft A1; the first planetary carrier is mounted on the second input drive shaft A2, and the second internal gear ring is fixed to the first planetary carrier by a connecting member.

[0046] The second internal gear ring is connected and fixed to the first planetary carrier by a connector, so that the first planetary gear set K1 and the second planetary gear set K2 can form a variety of different power transmission paths. Since the transmission ratios on different transmission paths are different, different power outputs can be obtained to meet the needs of various working conditions.

[0047] Specifically, the input shaft I is connected to the first input transmission shaft A1 via gear pair I1; the input shaft I is connected to the second input transmission shaft A2 via gear pair I2; the first internal gear ring is connected to the first output transmission shaft B1 via gear pair I3; the second planetary carrier is connected to the second output transmission shaft B2 via gear pair I4; and the first input transmission shaft A1 is connected to the third output transmission shaft B3 via gear pair I5.

[0048] A wet clutch C1 is mounted on the first output drive shaft B1; a wet clutch C2 is mounted on the second output drive shaft B2; and a wet clutch C3 is mounted on the third output drive shaft B3. The first output drive shaft B1, the second output drive shaft B2, and the third output drive shaft B3 serve as output ports for different gear positions. The wet clutches C1, C2, and C3 are used for gear switching, and their specific structures and operating principles employ conventional technology in this field. The clutch oil circuit mainly consists of a hydraulic oil tank, a filter, a fixed displacement pump, a relief valve, a speed control valve, and a solenoid directional valve. The clutch controls the main oil circuit pressure through the relief valve, controls the engagement and disengagement of the clutch through the on / off state of the solenoid directional valve, and controls the flow rate entering the clutch piston cylinder through the speed control valve. Ultimately, clutch shifting is achieved through the combined action of the relief valve, the solenoid directional valve, and the speed control valve.

[0049] The total power of the transmission system is input from the input shaft I and then divided into two branches. One branch is transmitted through the first input transmission shaft A1, which is equipped with a hydraulic transmission system to convert the input power of the input shaft I into hydraulic power for transmission. The other branch is transmitted through the second input transmission shaft A2, which still maintains the traditional mechanical power.

[0050] The hydraulic transmission system includes a variable displacement pump and a fixed displacement motor. The operating principle of the hydraulic transmission system is as follows: the fixed displacement motor drives the variable displacement pump. When the proportional electromagnet is energized, oil is discharged from the high-pressure port. When the pressure acting on the primary plunger exceeds its spring force, the primary plunger moves, the pilot valve deflects, and this causes the variable displacement plunger to move, rotating the swashplate of the variable displacement pump, thus outputting flow. If there is no current input to the proportional electromagnet or the input current is less than the starting current, the swashplate of the variable displacement pump does not rotate, and the variable displacement pump outputs no flow. The hydraulic transmission system controls the rotation of the swashplate angle of the variable displacement pump by controlling the on / off state or magnitude of the current to the proportional electromagnet, thereby changing the output flow of the variable displacement pump and adjusting the on / off state or magnitude of the hydraulic power.

[0051] The equivalent system can simulate the four working sections of the transmission system, as shown below:

[0052] Pure hydraulic gear (H segment): Engine power is transmitted from the input shaft to the first input drive shaft A1 via gear pair I1, and the input power is converted into hydraulic power through the hydraulic transmission system; then the hydraulic power is transmitted to the third output drive shaft B3 via gear pair I5, and output through the output shaft C, realizing pure hydraulic starting of the vehicle.

[0053] Low gear (HM1): The first planetary gear set K1 is working. One branch of the engine power is transmitted from the input shaft to the gear pair I2 to form mechanical power; the other branch is transmitted from the input shaft to the hydraulic transmission system via the gear pair I1 to form hydraulic power. The mechanical power is input from the first planetary carrier via the second input drive shaft A2, and the hydraulic power is input from the first sun gear via the first input drive shaft A1. After the two power paths converge, they are output from the first internal gear ring, transmitted to the third output drive shaft B3 via the gear pair I3, and finally output from the output shaft C.

[0054] High-speed gear (HM2): The second planetary gear set K2 is in operation. One branch of the engine power is transmitted from the input shaft to the gear pair I2 to form mechanical power; the other branch is transmitted from the input shaft to the hydraulic transmission system via the gear pair I1 to form hydraulic power. The mechanical power is input from the second internal gear ring via the second input drive shaft A2 and the first planetary carrier, and the hydraulic power is input from the second sun gear via the first input drive shaft A1. After the two power paths converge, they are output from the second planetary carrier, transmitted to the second output drive shaft B2 via the gear pair I4, and finally output from the output shaft C.

[0055] Reverse gear (R gear): The working principle of reverse gear is the same as that of pure hydraulic gear. It achieves the reversal of power output by controlling the engine steering in the opposite direction to forward gear.

[0056] Pure hydraulic gears (H segment) and reverse gears (R segment) are generally in non-working periods, and the duration of their range is relatively short, so transmission efficiency is generally not considered; while low-speed gears (HM1 segment) and high-speed gears (HM2 segment) are generally in working periods, and the duration of their range is relatively long, so transmission efficiency needs to be calculated in order to better optimize the structure of the transmission system.

[0057] Step S2, based on the equivalent model, construct the transmission chain, wherein:

[0058] Please see Figure 2 In the low-speed operating range, the input power of the input shaft I is divided into two branches. One branch is input to the first sun gear via the first input transmission shaft A1, such as... Figure 2 The bI branch path; another branch is input to the first planetary carrier via the second input drive shaft A2, as shown in the example. Figure 2 The aI branch route in the middle; after the power converges, it is output to the first output drive shaft B1 through the first internal gear ring, and then output through the output shaft C.

[0059] Please see Figure 3 In the high-speed gear operating range, the input power of the input shaft I is divided into two branches. One branch is input to the second sun gear via the first input transmission shaft A1, such as... Figure 3 The eI branch route; another branch is input to the first planetary carrier via the second input drive shaft A2, and then transported to the second internal gear ring, as shown. Figure 3 The dI route in the middle; after the power converges, it is output to the second output drive shaft B2 through the second planetary carrier, and then output through the output shaft C.

[0060] In both low and high speed ranges, it maintains a combined mechanical and hydraulic power system, employing power splitting technology to combine the advantages of hydraulic and mechanical transmission, thereby improving transmission efficiency, enhancing engine fuel economy, and enabling ultra-low stable vehicle speeds to meet the special needs of work vehicles.

[0061] Step S3: Fix the second input drive shaft and run the first input drive shaft, calculate the first transmission ratio from the output shaft C to the input shaft I; fix the first input drive shaft and run the second input drive shaft, calculate the second transmission ratio from the output shaft C to the input shaft I; sum the first transmission ratio and the second transmission ratio to obtain the transmission ratio from the output shaft to the input shaft under the two working sections.

[0062] The calculation process for the transmission ratio in the low-speed gear operating range is as follows:

[0063]

[0064]

[0065]

[0066] In the formula, This indicates the transmission ratio from the output shaft C to the input shaft I in the low-speed working range; This indicates the transmission ratio from output shaft C to input shaft I when the second input transmission shaft is fixed. This indicates the transmission ratio from output shaft C to input shaft I when the first input transmission shaft is fixed. This indicates the transmission ratio from the output shaft C to the first input shaft when the second input drive shaft is fixed; i bI This indicates the transmission ratio from the first input drive shaft to input shaft I; This indicates the transmission ratio from output shaft C to the second input shaft when the first input drive shaft is fixed; i aI This indicates the transmission ratio from the second input drive shaft to input shaft I.

[0067] The calculation process for the transmission ratio in the high-speed gear operating section is as follows:

[0068]

[0069]

[0070]

[0071] In the formula, Indicates the transmission ratio in the high-speed gear operating range; This indicates the transmission ratio from output shaft C to input shaft I when the first output drive shaft is fixed. This indicates the transmission ratio from output shaft C to input shaft I when the second output drive shaft is fixed. This indicates the transmission ratio from output shaft C to the second output shaft when the first output drive shaft is fixed; i eI This indicates the transmission ratio from the second output drive shaft to the input shaft I; This indicates the transmission ratio from output shaft C to the first output shaft when the second output drive shaft is fixed; i dI This indicates the transmission ratio from the first output drive shaft to the input shaft I.

[0072] Step S4: Calculate the transmission efficiency for the two working sections based on the transmission ratio under the two working sections using the meshing power method.

[0073] Transmission efficiency η in low-speed gear operating range HM1 Represented as:

[0074]

[0075] In the formula, This indicates the transmission ratio from input shaft I to output shaft C in the low-speed operating range; ψ x ψ represents the loss coefficient of power transmission in the drive train when the first planetary carrier is fixed; aI ψ represents the loss coefficient of the second input drive shaft. bI η represents the loss coefficient of the first input drive shaft. aI Indicates the transmission efficiency of the second input drive shaft; η bI η1 represents the transmission efficiency of the first input drive shaft; η1 represents the transmission efficiency of the lower gear in the low-speed working section.

[0076] Transmission efficiency η in high-speed gear operating section HM2 Represented as:

[0077]

[0078] In the formula, This indicates the transmission ratio from input shaft I to output shaft C in the high-speed gear operating range; ψ y ψ represents the loss coefficient of power transmission in the drive train when the second planetary carrier is fixed; dI ψ represents the loss coefficient of the first output drive shaft; eI η represents the loss coefficient of the second output drive shaft. dI Indicates the transmission efficiency of the first output drive shaft; η eI η1 represents the transmission efficiency of the second output drive shaft; η2 represents the transmission efficiency of the lower gear shift gear in the low-speed working section.

[0079] Specifically, in the low-speed gear operating range:

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086] In the formula, i1 represents the transmission ratio of gear pair I1; i2 represents the transmission ratio of gear pair I2; i3 represents the transmission ratio of gear pair I3; k1 represents the characteristic parameter of the first planetary gear set; k2 represents the characteristic parameter of the second planetary gear set; and e represents the displacement ratio of the hydraulic transmission system.

[0087] Specifically, in the high-speed gear operating section:

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095] In the formula, i4 represents the transmission ratio of gear pair I4.

[0096] In this embodiment, the values ​​of each parameter in the above formula are shown in Table 1:

[0097] Table 1. Values ​​of each parameter

[0098] Parameter Value Parameter Value ​ 2.83 i3 2 [k2] 2.83 i4 0.9 ​ 1 i5 1.1 i2 1.5

[0099] In Table 1, i5 represents the transmission ratio of gear pair I5.

[0100] Substituting the parameters from Table 1, we get:

[0101]

[0102]

[0103] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system, characterized in that, Includes the following steps: Step S1: Construct an equivalent model of the transmission system. The equivalent model includes an input shaft, an output shaft, a first planetary gear set and a second planetary gear set, an input drive shaft, and an output drive shaft. The input drive shaft includes a first input drive shaft and a second input drive shaft, both connected to the input shaft. The output drive shaft includes a first output drive shaft and a second output drive shaft, both connected to the output shaft. The first planetary gear set includes a first sun gear, a first planet gear, a first planet carrier, and a first internal gear ring; the second planetary gear set includes a second sun gear, a second planet gear, a second planet carrier, and a second internal gear ring; both the first sun gear and the second sun gear are mounted on the first input drive shaft; the first planet carrier is mounted on the second input drive shaft, and the second internal gear ring is fixed to the first planet carrier by a connecting member; The first input drive shaft is equipped with a hydraulic transmission system for converting the input power of the input shaft into hydraulic power for transmission. Step S2, based on the equivalent model, construct the transmission chain, wherein: In the low-speed range, the input power of the input shaft is divided into two branches. One branch is input to the first sun gear via the first input drive shaft; the other branch is input to the first planet carrier via the second input drive shaft. After the power is combined, it is output to the first output drive shaft via the first internal gear ring, and finally output through the output shaft. In the high-speed gear operating range, the input power of the input shaft is divided into two branches. One branch is input to the second sun gear via the first input drive shaft; the other branch is input to the first planetary carrier via the second input drive shaft, and then transmitted to the second internal gear ring. After the power is merged, it is output to the second output drive shaft via the second planetary carrier, and finally output through the output shaft. Step S3: Fix the second input drive shaft and run the first input drive shaft, calculate the first transmission ratio from the output shaft to the input shaft; fix the first input drive shaft and run the second input drive shaft, calculate the second transmission ratio from the output shaft to the input shaft; sum the first transmission ratio and the second transmission ratio to obtain the transmission ratio from the output shaft to the input shaft under the two working sections respectively; Step S4: Calculate the transmission efficiency of the transmission system based on the transmission ratio using the meshing power method.

2. The method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system according to claim 1, characterized in that, The calculation process for the transmission ratio in the low-speed gear operating range is as follows: In the formula, This indicates the transmission ratio from the output shaft to the input shaft in the low-speed operating range; This indicates the transmission ratio from the output shaft to the input shaft when the second input transmission shaft is fixed. This indicates the transmission ratio from the output shaft to the input shaft when the first input transmission shaft is fixed. This indicates the transmission ratio from the output shaft to the first input shaft when the second input drive shaft is fixed; i bI This indicates the transmission ratio from the first input drive shaft to the input shaft; This indicates the transmission ratio from the output shaft to the second input shaft when the first input drive shaft is fixed; i aI This indicates the transmission ratio from the second input drive shaft to the input shaft.

3. The method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system according to claim 2, characterized in that, Transmission efficiency η in low-speed gear operating range HM1 Represented as: In the formula, This indicates the transmission ratio from the input shaft to the output shaft in the low-speed operating range; ψ x ψ represents the loss coefficient of power transmission in the drive train when the first planetary carrier is fixed; aI ψ represents the loss coefficient of the second input drive shaft; bI This represents the loss coefficient of the first input drive shaft; η aI This indicates the transmission efficiency of the second input drive shaft; η bI This indicates the transmission efficiency of the first input drive shaft; η1 represents the transmission efficiency of the lower gear in the low-speed working section.

4. The method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system according to claim 3, characterized in that, The calculation process for the transmission ratio in the high-speed gear operating section is as follows: In the formula, This indicates the transmission ratio from the output shaft to the input shaft in the high-speed gear operating range; This indicates the transmission ratio from the output shaft to the input shaft when the first output drive shaft is fixed. This indicates the transmission ratio from the output shaft to the input shaft when the second output drive shaft is fixed. This indicates the transmission ratio from the first output drive shaft to the second output drive shaft when the first output drive shaft is fixed; i eI This indicates the transmission ratio from the second output drive shaft to the input shaft; This indicates the transmission ratio from the output shaft to the first output shaft when the second output drive shaft is fixed; i dI This indicates the transmission ratio from the first output drive shaft to the input shaft.

5. The method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system according to claim 4, characterized in that, Transmission efficiency η in low-speed gear operating range HM2 Represented as: In the formula, This indicates the transmission ratio from the input shaft to the output shaft in the high-speed gear operating range; ψ y ψ represents the loss coefficient of power transmission in the drive train when the second planetary carrier is fixed; dI ψ represents the loss coefficient of the first output drive shaft; eI This represents the loss coefficient of the second output drive shaft; η dI Indicates the transmission efficiency of the first output drive shaft; η eI η1 represents the transmission efficiency of the second output drive shaft; η2 represents the transmission efficiency of the lower gear shift gear in the low-speed working section.

6. The method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system according to claim 1, characterized in that, The input shaft is connected to the first input drive shaft via gear pair I1; the input shaft is connected to the second input drive shaft via gear pair I2; the first internal gear ring is connected to the first output drive shaft via gear pair I3; and the second planetary carrier is connected to the second output drive shaft via gear pair I4.

7. The method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system according to claim 1, characterized in that, The output drive shaft also includes a third output drive shaft, and the first input drive shaft and the third output drive shaft are connected by a gear pair I5.

8. The method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system according to claim 7, characterized in that, A wet clutch C1 is provided on the first output shaft; a wet clutch C2 is provided on the second output shaft; and a wet clutch C3 is provided on the third output shaft.

9. The method for calculating the transmission efficiency of a high-torque continuously variable transmission (CVT) system according to claim 1, characterized in that, The hydraulic transmission system includes a variable pump and a fixed displacement motor. The fixed displacement motor is used to drive the variable pump and control the on / off state and flow rate of the variable pump.

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