Compound power system of a hybrid tractor and its control method

Abstract

The present invention provides a compound power system and a control method thereof for a hybrid tractor, comprising an engine, an electric motor, a transmission system, a hydraulic transmission device, a clutch assembly, a transmission device and a lifting device; the engine and the electric motor are respectively connected to the transmission system, and the output end of the transmission system is a main power output end and a PTO output end; the PTO output end is connected to the input end of the hydraulic transmission device, the output end of the hydraulic transmission device is connected to the lifting device, the main power output end is connected to the lifting device, and by controlling the displacement ratio of the hydraulic transmission device and selectively controlling the engagement of the clutch assembly, a continuously variable transmission ratio between the PTO output end and the lifting device, between the main power output end or / and the electric motor and the lifting device, and between the PTO output end and the main power output end or / and the electric motor and the lifting device is provided. The present invention can be applicable to various working conditions where a tractor drives a lifting device.

Description

Technical Field

[0001] The present invention relates to the field of agricultural machinery or tractors, and particularly to a compound power system of a hybrid tractor and its control method. Background Art

[0002] China is a large agricultural country. As agricultural machinery, tractors play a crucial role in the agricultural development of China. The power of traditional tractors all comes from engines, which have problems such as numerous gears, complex operations, high pollutant emissions, complex transmission systems and low efficiency. With the rise of hybrid power technology, using engines and motors as the power of tractors can effectively reduce the emissions and fuel consumption of tractors, and has become a current research hotspot.

[0003] The application of hybrid power technology in passenger cars is earlier and the technology is relatively mature. The existing research on hybrid tractors draws on many experiences of passenger cars. The emergence of hybrid tractors has reduced the emissions and energy consumption of tractors. However, compared with passenger cars, tractors need to take into account the complex field operation conditions. In addition, power interruption will occur when shifting gears in the engine drive mode of hybrid tractors.

[0004] Compared with traditional tractors, electric tractors have the advantages of comfort, cleanliness, low noise, no pollution, no emissions, simplicity, reliability and low use cost, reducing the degree of dependence of agricultural production on fossil energy and improving the farmland environment and crop quality. For existing hybrid tractors, more power coupling of motors and engines occurs. When the power output by the PTO lifts heavy objects, power shortage often occurs or the lifting state cannot be stably maintained. In addition, when the tractor drives the lifting equipment, due to uneven power distribution, the lifting equipment cannot rise stably, or heavy objects cannot be stably lifted in the low-speed walking state. Summary of the Invention

[0005] Aiming at the deficiencies in the prior art, the present invention provides a compound power system of a hybrid tractor and its control method, which can be applicable to various working conditions of tractors driving lifting equipment and has the functions of energy reuse and emergency guarantee.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] A compound power system for a hybrid tractor, comprising an engine, an electric motor and a transmission system. The engine and the electric motor are respectively connected to the transmission system. The output end of the transmission system is a main power output end and a PTO output end. The main power output end is used to connect to a differential, and the PTO output end is used for external work. It further includes a hydraulic transmission device, a clutch assembly, a transmission device and a lifting device. The PTO output end is connected to the input end of the hydraulic transmission device. The output end of the hydraulic transmission device is connected to the lifting device through an intermediate shaft. The main power output end is connected to the lifting device. The electric motor is connected to the lifting device through the transmission device. The output end of the transmission system further includes a secondary power output end, which is connected to the transmission device. By controlling the displacement ratio of the hydraulic transmission device and selectively controlling the engagement of the clutch assembly, a continuously variable transmission ratio between the PTO output end and the lifting device, between the main power output end or / and the electric motor and the lifting device, and between the PTO output end and the main power output end or / and the electric motor and the lifting device is provided.

[0008] Further, the hydraulic transmission device includes a variable pump, a pump / motor mechanism, solenoid directional valve V 1 , an accumulator, solenoid directional valve V 2 and a check valve. The input end of the variable pump is connected to the PTO output end. The variable pump is communicated with the pump / motor mechanism. A solenoid directional valve V 1 and a solenoid directional valve V 2 are arranged in parallel between the variable pump and the pump / motor mechanism. The outlet of the solenoid directional valve V 1 is respectively communicated with the accumulator and the fuel tank. The working pressure of the accumulator is greater than the rated output pressure of the variable pump. The solenoid valve Sb1 of the solenoid directional valve V 1 works to connect the accumulator with the outlet of the variable pump and connect the fuel tank with the inlet of the variable pump. The solenoid valve Sb2 of the solenoid directional valve V 1 works to connect the accumulator with the outlet of the pump / motor mechanism and connect the fuel tank with the inlet of the pump / motor mechanism. A check valve is installed at the outlet of the variable pump.

[0009] Further, the clutch assembly includes a first clutch C 1 , a second clutch C 2 , a third clutch C 3 , a fourth clutch C 4 and a fifth clutch C 5 . The first clutch C 1 is used to selectively connect the PTO output end to the input end of the variable pump. The second clutch C 2 is used to selectively connect the output end of the electric motor to the transmission device. The third clutch C 3For selectively connecting the main power output end to the intermediate shaft; the fourth clutch C 4 For selectively connecting the auxiliary power output end to the transmission device; the fifth clutch C 5 For selectively connecting the output end of the pump / motor mechanism to the intermediate shaft.

[0010] Furthermore, by adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the clutch assembly, solenoid directional valve V 1 and solenoid directional valve V 2 engagement, provide multiple transmission modes between the PTO output end and the lifting device, between the main power output end and the lifting device, between the motor and the lifting device, between the PTO output end and the main power output end and the lifting device, between the motor and the main power output end and the lifting device, between the PTO output end, the main power output end and the motor and the lifting device.

[0011] Furthermore, by adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 and the fifth clutch C 5 engagement, provide a hydraulic transmission of the PTO output between the PTO output end and the lifting device;

[0012] By adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 and the fifth clutch C 5 engagement, selectively control the solenoid valve Sb1 of the solenoid directional valve V 1 work, provide a compound hydraulic transmission of the PTO output between the PTO output end and the lifting device;

[0013] By selectively controlling the engagement of the third clutch C 3 provide a mechanical transmission of the main power output between the main power output end and the lifting device;

[0014] By selectively controlling the engagement of the second clutch C 2 provide a mechanical transmission of the motor output between the motor and the lifting device.

[0015] Furthermore, by selectively controlling the engagement of the second clutch C 2 and the fourth clutch C 4 provide an auxiliary motor output mechanical transmission of the auxiliary power between the engine and the motor and the lifting device;

[0016] By adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 the third clutch C 3 and the fifth clutch C 5Engagement, providing a combined mechanical-hydraulic transmission I of PTO and main power between the PTO output end and the main power output end and the lifting device;

[0017] By adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 , the third clutch C 3 and the fifth clutch C 5 to engage, controlling the solenoid valve Sb 1 of the electromagnetic directional control valve V 1 to be energized, providing a combined mechanical-hydraulic transmission II of PTO and main power between the PTO output end and the main power output end and the lifting device.

[0018] Furthermore, by adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 , the second clutch C 2 and the fifth clutch C 5 to engage, providing a combined mechanical-hydraulic transmission I of PTO and motor between the PTO output end and the motor and the lifting device;

[0019] By adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 , the second clutch C 2 and the fifth clutch C 5 to engage and controlling the solenoid valve Sb 1 of the electromagnetic directional control valve V 1 to be energized, providing a combined mechanical-hydraulic transmission II of PTO and motor between the PTO output end and the motor and the lifting device

[0020] By adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 , the second clutch C 2 , the fourth clutch C 4 and the fifth clutch C 5 to engage and controlling the solenoid valve Sb 1 of the electromagnetic directional control valve V 1 to be energized, providing a combined mechanical-hydraulic transmission III of PTO and motor between the PTO output end and the motor and the lifting device.

[0021] Furthermore, by adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 , the second clutch C 2 , the third clutch C 3 and the fifth clutch C 5 to engage, providing a combined mechanical-hydraulic transmission I of PTO, main power and motor between the PTO output end, the engine and the motor and the lifting device

[0022] By adjusting the displacement ratio of the hydraulic transmission device and selectively controlling the first clutch C 1 , the second clutch C 2 , the third clutch C 3 and the fifth clutch C 5 are engaged and the solenoid valve Sb 1 of the electromagnetic directional control valve V 1 is energized to provide a mechanical-hydraulic transmission II that combines PTO, main power, and motor between the PTO output end, the engine, the motor, and the lifting device.

[0023] Further, by engaging the fifth clutch C 5 and controlling the solenoid valve Sb 1 of the electromagnetic directional control valve V 2 to be energized, potential energy recovery transmission between the lifting device and the accumulator is provided.

[0024] A control method for a composite power system of a hybrid tractor includes the following steps:

[0025] Obtain the pressure value P1 at the outlet of the accumulator through the first pressure sensor; obtain the pressure value P0 at the outlet of the variable pump through the second pressure sensor; obtain the traveling state of the tractor through the first speed sensor; obtain the height h of the lifted heavy object through the height sensor; determine the speed V of the lifted heavy object through the second speed sensor h ; determine the vibration amplitude A of the lifted heavy object through the vibration sensor;

[0026] The control system collects the SOC of the motor battery, the traveling speed v of the tractor, the pressure value P0 at the outlet of the variable pump, the pressure value P1 at the outlet of the accumulator, the height h of the lifted heavy object, the speed V of the lifted heavy object h and the vibration amplitude A of the lifted heavy object;

[0027] When the traveling speed v of the tractor = 0, if the height h of the lifted heavy object ≤ the first set height h 0 , and the speed V of the lifted heavy object h is uniform, the control system controls a hydraulic transmission for PTO output to be formed between the PTO output end and the lifting device; if the height h of the lifted heavy object ≤ the first set height h 0 , and the speed V of the lifted heavy object h is uniform, the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls a composite hydraulic transmission for PTO output to be formed between the PTO output end and the lifting device; if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object h ​When it is at a constant speed, the control system controls the formation of a main power output mechanical transmission between the main power output end and the lifting device; if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object h changes with uniform acceleration, the control system controls the formation of a mechanical-hydraulic transmission one that combines PTO and main power between the PTO output end, the main power output end and the lifting device; if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object h changes with uniform acceleration, and the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls the formation of a mechanical-hydraulic transmission two that combines PTO and main power between the PTO output end, the main power output end and the lifting device;

[0028] When the traveling speed v of the tractor ≠ 0, if the height h of the lifted heavy object ≤ the first set height h 0 , and the speed V of the lifted heavy object h is at a constant speed, and SOC > the health state limit value SOC min of the battery, the control system controls the formation of a motor output mechanical transmission between the motor and the lifting device;

[0029] If the height h of the lifted heavy object ≤ the first set height h 0 , and the speed V of the lifted heavy object h is at a constant speed, and SOC < 1.5 * SOC min , the control system controls the formation of an auxiliary power-assisted motor output mechanical transmission between the engine, the motor and the lifting device;

[0030] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is at a constant speed, and SOC > the health state limit value SOC min of the battery, the control system controls the formation of a mechanical-hydraulic transmission one that combines PTO and motor between the PTO output end, the motor and the lifting device;

[0031] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is at a constant speed, and SOC > the health state limit value SOC min of the battery, the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls the formation of a mechanical-hydraulic transmission two that combines PTO and motor between the PTO output end, the motor and the lifting device;

[0032] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniform, and SOC < 1.5 * SOC min , when the vibration amplitude A of the lifted heavy object is greater than the set value, the control system controls the PTO output end and the motor to form a combined mechanical - hydraulic transmission of PTO and motor with the lifting equipment.

[0033] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniformly accelerated, and SOC > SOC min , when the control system controls the engine and the motor to form a combined mechanical - hydraulic transmission of PTO, main power and motor with the lifting equipment.

[0034] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniformly accelerated, and SOC > SOC min , when the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls the engine and the motor to form a combined mechanical - hydraulic transmission of PTO, main power and motor with the lifting equipment.

[0035] The beneficial effects of the present invention are as follows:

[0036] 1. The composite power system and its control method of the hybrid tractor described in the present invention can be applied to various working conditions of the tractor driving the lifting equipment, and have the functions of energy reuse and emergency guarantee.

[0037] 2. The composite power system and its control method of the hybrid tractor described in the present invention control the displacement ratio of the hydraulic transmission mechanism, control the engagement of the clutch assembly, and provide various transmission modes between the PTO output end and the lifting equipment, between the main power output end and the lifting equipment, between the motor and the lifting equipment, between the PTO output end and the main power output end and the lifting equipment, between the motor and the main power output end and the lifting equipment, between the PTO output end, the main power output end and the motor and the lifting equipment.

[0038] 3. The control method of the composite power system of the hybrid tractor described in the present invention gives the transmission modes of the tractor under different working conditions or conditions. When it is found that the lifted heavy object shakes or lacks power, other power is added in time to prevent danger. The present invention can also meet the requirement of lifting heavy objects when the tractor is running at a low speed. Brief Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. The drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, it is obvious that other drawings can also be obtained based on these drawings.

[0040] Figure 1 It is a schematic diagram of the composite power system of the hybrid tractor described in the present invention.

[0041] Figure 2 It is a hydraulic transmission path diagram of the PTO output described in the present invention.

[0042] Figure 3 It is a composite hydraulic transmission path diagram of the PTO output described in the present invention.

[0043] Figure 4 It is a transmission path diagram of the potential energy recovery of the lifting device described in the present invention.

[0044] Figure 5 It is a mechanical transmission path diagram of the main power output described in the present invention.

[0045] Figure 6 It is a mechanical transmission path diagram of the motor output described in the present invention.

[0046] Figure 7 It is a mechanical transmission path diagram of the auxiliary power auxiliary motor output described in the present invention.

[0047] Figure 8 It is a mechanical-hydraulic transmission path diagram of the composite of the PTO and the main power in the present invention.

[0048] Figure 9 It is a mechanical-hydraulic transmission path diagram of the composite of the PTO and the main power in the present invention (Path 2).

[0049] Figure 10 It is a mechanical-hydraulic transmission path diagram of the composite of the PTO and the motor in the present invention (Path 1).

[0050] Figure 11 It is a mechanical-hydraulic transmission path diagram of the composite of the PTO and the motor in the present invention (Path 2).

[0051] Figure 12 It is a mechanical-hydraulic transmission path diagram of the composite of the PTO and the motor in the present invention (Path 3).

[0052] Figure 13It is a path diagram of the mechanical hydraulic transmission that combines PTO, prime power, and motor of the present invention.

[0053] Figure 14 It is a second path diagram of the mechanical hydraulic transmission that combines PTO, prime power, and motor of the present invention.

[0054] In the figure:

[0055] 1 - Engine; 2 - Motor; 3 - Transmission system; 3 - 1 - Prime power output end; 3 - 2 - PTO output end; 3 - 3 - Auxiliary power output end; 4 - Third clutch C 3 ; 5 - First gear pair; 6 - Second gear pair; 7 - Second clutch C 2 ; 8 - Transmission device; 9 - Differential assembly; 10 - Hydraulic transmission input gear pair; 11 - First clutch C 1 ; 12 - Hydraulic transmission device; 12 - 1 - Variable pump; 12 - 2 - Pump / motor mechanism; 12 - 3 - Electromagnetic reversing valve V 1 ; 12 - 4 - Accumulator; 12 - 5 - Fuel tank; 12 - 6 - Electromagnetic reversing valve V 2 ; 12 - 7 - Check valve; 13 - Third gear pair; 14 - Lifting equipment; 15 - Fourth clutch C 4 ; 16 - Fifth clutch C 5 ; 17 - Intermediate shaft. Detailed implementation manners

[0056] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0057] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as a limitation of the present invention.

[0058] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are 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, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0059] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0060] As Figure 1 shown, the compound power system of the hybrid tractor described in the present invention includes an engine 1, an electric motor 2, a transmission system 3, a hydraulic transmission device 12, a clutch assembly, and a transmission device 8. The engine 1 and the electric motor 2 are respectively used as input ends to input into the transmission system 3. The output end of the transmission system 3 includes a main power output end 3-1, a PTO output end 3-2, and a secondary power output end 3-3. The main power output end 3-1 is used to transmit power to the differential assembly 9. The PTO output end 3-2 is used to do work externally. The secondary power output end 3-3 is used to transmit power to the transmission device 8. The transmission system 3 is an existing traditional system in the tractor. It may be a transmission system including two gears or a transmission system including at least one planetary gear train and several gear pairs. Therefore, the specific structure of the transmission system 3 will not be described further.

[0061] The electric motor 2 is connected to the input end of the transmission device 8 through a second gear pair 6. The output end of the transmission device 8 is connected to the output end of the hydraulic transmission device 12. The transmission device 8 may be a planetary gear train or at least a one-stage reducer.

[0062] The hydraulic transmission device 12 includes a variable pump 12-1, a pump / motor mechanism 12-2, and an electromagnetic reversing valve V 112-3, accumulator 12-4, electromagnetic directional valve V 2 12-6 and check valve 12-7. The pump / motor mechanism 12-2 is a device that can switch functions between a hydraulic pump and a hydraulic motor. That is, when mechanical energy is input to the pump / motor mechanism 12-2, the pump / motor mechanism 12-2 outputs hydraulic energy; when hydraulic energy is input to the pump / motor mechanism 12-2, the pump / motor mechanism 12-2 outputs mechanical energy. The input shaft of the variable pump 12-1 is connected to the PTO output end 3-2 through the hydraulic transmission input gear pair 10; generally, the speed ratio of the hydraulic transmission input gear pair 10 is less than 1, which is used to increase the rotational speed of the input shaft of the variable pump 12-1 to better match the rated rotational speed of the variable pump 12-1. The variable pump 12-1 drives the pump / motor mechanism 12-2; a check valve 12-7 is provided between the variable pump 12-1 and the pump / motor mechanism 12-2 for the one-way flow of oil; a three-position four-way electromagnetic directional valve V 1 12-3 and a two-position two-way electromagnetic directional valve V 2 12-6, the three-position four-way electromagnetic directional valve V 1 12-3 includes a P port, a T port, an A port, and a B port; where the P port is connected to the outlet of the variable pump 12-1, the T port is connected to the inlet of the variable pump 12-1, the A port is connected to the accumulator 12-4, and the B port is connected to the fuel tank 12-5; the output end of the pump / motor mechanism 12-2 is connected to the lifting device 14 through the intermediate shaft 17. The output end of the transmission device 8 is connected to the intermediate shaft 17 through the third gear pair 13.

[0063] As Figure 1 shown, the clutch assembly includes a first clutch C 1 11, a second clutch C 2 7, a third clutch C 3 4, a fourth clutch C 4 15 and a fifth clutch C 5 16; the first clutch C 1 11 is used to selectively connect the PTO output end 3-2 to the variable pump 12-1 through the hydraulic transmission input gear pair 10; the second clutch C 2 7 is used to selectively connect the output end of the motor 2 to the transmission device 8 through the second gear pair 6; the third clutch C 3 4 is used to selectively connect the main power output end 3-1 to the intermediate shaft 17 through the first gear pair 5; the fourth clutch C 4 15 is used to selectively connect the auxiliary power output end 3-3 to the transmission device. The fifth clutch C 516 is used to selectively connect the output end of the pump / motor mechanism 12-2 to the intermediate shaft 17.

[0064] As shown in Table 1, by adjusting the displacement ratio of the hydraulic transmission device 12 and selectively controlling the engagement of the clutch assembly, various transmission modes are provided between the PTO output end and the lifting device, between the main power output end and the lifting device, between the motor and the lifting device, between the PTO output end and the main power output end and the lifting device, between the motor and the main power output end and the lifting device, between the PTO output end, the main power output end and the motor and the lifting device.

[0065] Hydraulic transmission of PTO output: As Figure 2 shown, engage the first clutch C 1 11 and the fifth clutch C 5 16. The PTO output end 3-2 is connected to the variable pump 12-1 through the hydraulic transmission input gear pair 10. At this time, the pump / motor mechanism 12-2 is in the hydraulic motor working condition, and the variable pump 12-1 drives the pump / motor mechanism 12-2 to drive the lifting device 14 to work, that is, a hydraulic transmission of PTO output is formed between the PTO output end 3-2 and the lifting device 14.

[0066] Compound hydraulic transmission of PTO output: As Figure 3 shown, engage the first clutch C 1 11 and the fifth clutch C 5 16, control the solenoid valve Sb 1 of the solenoid directional valve V 1 12-3 to be energized. The PTO output end 3-2 is connected to the variable pump 12-1 through the hydraulic transmission input gear pair 10. At this time, the pump / motor mechanism 12-2 is in the hydraulic motor working condition, and the outlet of the variable pump 12-1 is connected to the pump / motor mechanism 12-2. Since the solenoid valve Sb 1 is energized, the accumulator 12-4 releases the internal pressure. The hydraulic energy at the outlet of the variable pump 12-1 and the pressure released in the accumulator 12-4 jointly drive the pump / motor mechanism 12-2 to drive the lifting device 14 to work, that is, a compound hydraulic transmission of PTO output is formed between the PTO output end 3-2 and the lifting device 14.

[0067] Potential energy recovery of the lifting device 14: As Figure 4 shown, engage the fifth clutch C 5 16, control the solenoid valve Sb 1 of the solenoid directional valve V 2It is energized. At this time, the pump / motor mechanism 12-2 is in the hydraulic pump working condition. The potential energy released by the lifting device 14 drives the pump / motor mechanism 12-2 to work. When the outlet pressure of the pump / motor mechanism 12-2 is greater than the set pressure of the accumulator 12-4, the outlet of the pump / motor mechanism 12-2 stores energy in the accumulator 12-4, and the fuel tank 12-5 can supply oil to the inlet of the pump / motor mechanism 12-2.

[0068] Main power output mechanical transmission: As Figure 5 shown, engage the third clutch C 3 5. The main power output end 3-1 is connected to the intermediate shaft 17 through the first gear pair 5, thereby driving the lifting device 14 to work. That is, a main power output mechanical transmission is formed between the main power output end 3-1 and the lifting device 14. Generally, the main power output mechanical transmission occurs when the tractor is in a standby state or a non-traveling state.

[0069] Motor output mechanical transmission: As Figure 6 shown, engage the second clutch C 2 7. The motor 2 is connected to the transmission device 8 through the second gear pair 6. The output end of the transmission device 8 is connected to the intermediate shaft 17 through the third gear pair 13, thereby driving the lifting device 14 to work. That is, a motor output mechanical transmission is formed between the motor 2 and the lifting device 14.

[0070] Auxiliary power-assisted motor output mechanical transmission: As Figure 7 shown, engage the second clutch C 2 7 and the fourth clutch C 4 14. The motor 2 is connected to the transmission device 8 through the second gear pair 6. The engine 1 inputs power to the transmission device 8 through the auxiliary power output end 3-3. The power of the motor 2 and the power of the engine 1 converge in the transmission device 8. The output end of the transmission device 8 is connected to the intermediate shaft 17 through the third gear pair 13, thereby driving the lifting device 14 to work. That is, an auxiliary power-assisted motor output mechanical transmission is formed between the engine 1 and the motor 2 and the lifting device 14. Generally, the auxiliary power-assisted motor output mechanical transmission occurs when the tractor is in a standby state or a non-traveling state, or when the electric energy of the battery driving the motor 2 is insufficient.

[0071] Combined mechanical-hydraulic transmission of PTO and main power one: As Figure 8 shown, engage the first clutch C 1 11, the third clutch C 3 5 and the fifth clutch C 516, one power is input into the variable pump 12-1 through the PTO output terminal 3-2, at this time, the pump / motor mechanism 12-2 is in the hydraulic motor working state, the variable pump 12-1 drives the pump / motor mechanism 12-2 to rotate the intermediate shaft 17, and the other power is input into the intermediate shaft 17 through the main power output terminal 3-1 and the first gear pair 5. After the two powers converge at the intermediate shaft 17, they drive the lifting device 14 to work. That is, the PTO output terminal 3-2 and the main power output terminal 3-1 and the lifting device 14 form a mechanical hydraulic transmission of PTO and main power compound.

[0072] PTO and active power combined mechanical hydraulic transmission 2: Figure 9 As shown, the first clutch C is engaged. 1 11. Third clutch C 3 5 and fifth clutch C 5 16. Control solenoid reversing valve V 1 12-3 solenoid valve Sb 1 Power is supplied, and a power path is input into the variable pump 12-1 through the PTO output terminal 3-2. 1 When the power is supplied, the accumulator 12-4 releases the internal pressure, and the hydraulic energy at the outlet of the variable pump 12-1 and the pressure released in the accumulator 12-4 jointly drive the pump / motor mechanism 12-2 to drive the intermediate shaft 17 to rotate; another power is input into the intermediate shaft 17 through the main power output terminal 3-1 and the first gear pair 5, and the two powers converge at the intermediate shaft 17 to drive the lifting device 14 to work. That is, the PTO output terminal 3-2 and the main power output terminal 3-1 and the lifting device 14 form a mechanical hydraulic transmission 2 of PTO and main power compound.

[0073] PTO and electric motor composite mechanical hydraulic transmission 1: Figure 10 As shown, the first clutch C is engaged. 1 11. Second clutch C 2 7 and fifth clutch C 5 16, one power is input into the variable pump 12-1 through the PTO output terminal 3-2, at this time, the pump / motor mechanism 12-2 is in the hydraulic motor working state, the variable pump 12-1 drives the pump / motor mechanism 12-2 to rotate the intermediate shaft 17, and the other power is input into the transmission device 8 through the motor 2, and the transmission device 8 then inputs the power into the intermediate shaft 17. After the two powers converge at the intermediate shaft 17, they drive the lifting device 14 to work. That is, the PTO output terminal 3-2 and the motor 2 and the lifting device 14 form a mechanical hydraulic transmission of the PTO and the motor.

[0074] PTO and electric motor composite mechanical hydraulic transmission 2: Figure 11 As shown, the first clutch C is engaged. 1 11. Second clutch C 27 and the fifth clutch C 5 16, control the electromagnetic reversing valve V 1 The solenoid valve Sb of 12 - 3 1 Gets powered on. One path of power is input into the variable pump 12 - 1 through the PTO output end 3 - 2. Since the solenoid valve Sb 1 Gets powered on, the accumulator 12 - 4 releases the internal pressure. The hydraulic energy at the outlet of the variable pump 12 - 1 and the pressure released in the accumulator 12 - 4 jointly drive the pump / motor mechanism 12 - 2 to drive the intermediate shaft 17 to rotate; Another path of power is input into the transmission device 8 through the motor 2, and the transmission device 8 then inputs the power into the intermediate shaft 17. After the two paths of power converge on the intermediate shaft 17, they drive the lifting device 14 to work. That is, a PTO and motor composite mechanical - hydraulic transmission II is formed between the PTO output end 3 - 2 and the motor 2 and the lifting device 14.

[0075] PTO and motor composite mechanical - hydraulic transmission III: As Figure 12 shown, engage the first clutch C 1 11, the second clutch C 2 7, the fourth clutch C 4 14 and the fifth clutch C 5 16, control the electromagnetic reversing valve V 1 The solenoid valve Sb of 12 - 3 1 Gets powered on. The first path of power is input into the variable pump 12 - 1 through the PTO output end 3 - 2. Since the solenoid valve Sb 1 Gets powered on, the accumulator 12 - 4 releases the internal pressure. The hydraulic energy at the outlet of the variable pump 12 - 1 and the pressure released in the accumulator 12 - 4 jointly drive the pump / motor mechanism 12 - 2 to drive the intermediate shaft 17 to rotate; The second path of power is input into the transmission device 8 through the motor 2, and the third path of power is input into the transmission device 8 through the engine 1. After the second path of power and the third path of power converge in the transmission device 8, they are input into the intermediate shaft 17. After converging with the first path of power on the intermediate shaft 17, they drive the lifting device 14 to work. That is, a PTO and motor composite mechanical - hydraulic transmission III is formed between the PTO output end 3 - 2, the engine 1 and the motor 2 and the lifting device 14. In this transmission mode, generally, the power provided by the auxiliary power output end 3 - 3 is not large and can be regarded as making up for the energy generated by the accumulator 12 - 4, because the energy generated by the accumulator 12 - 4 is limited and the accumulator 12 - 4 will fail during long - term operation.

[0076] PTO, main power and motor composite mechanical - hydraulic transmission I: As Figure 13 shown, engage the first clutch C 1 11, the second clutch C 2 7, the third clutch C 3 5 and the fifth clutch C 516. The first power is input into the variable pump 12-1 through the PTO output end 3-2. At this time, the pump / motor mechanism 12-2 is in the hydraulic motor working condition, and the variable pump 12-1 drives the pump / motor mechanism 12-2 to rotate the intermediate shaft 17; the second power is input into the intermediate shaft 17 through the main power output end 3-1 and the first gear pair 5; the third power is input into the transmission 8 through the motor 2, and the transmission 8 then inputs the power into the intermediate shaft 17. After the three-way power converges on the intermediate shaft 17, it drives the lifting device 14 to work. That is, a combined mechanical-hydraulic transmission one of PTO, main power, and motor is formed between the PTO output end 3-2, the engine 1, and the motor 2 and the lifting device 14.

[0077] Combined mechanical-hydraulic transmission two of PTO, main power, and motor: As Figure 14 shown, engage the first clutch C 1 11, the second clutch C 2 7, the third clutch C 3 5 and the fifth clutch C 5 16, control the solenoid valve Sb 1 of the solenoid valve of the electromagnetic directional valve V 1 12-3 to be energized. The first power is input into the variable pump 12-1 through the PTO output end 3-2. Since the solenoid valve Sb 1 is energized, the accumulator 12-4 releases the internal pressure. The hydraulic energy at the outlet of the variable pump 12-1 and the pressure released in the accumulator 12-4 jointly drive the pump / motor mechanism 12-2 to drive the intermediate shaft 17 to rotate; the second power is input into the intermediate shaft 17 through the main power output end 3-1 and the first gear pair 5; the third power is input into the transmission 8 through the motor 2, and the transmission 8 then inputs the power into the intermediate shaft 17. After the three-way power converges on the intermediate shaft 17, it drives the lifting device 14 to work. That is, a combined mechanical-hydraulic transmission one of PTO, main power, and motor is formed between the PTO output end 3-2, the engine 1, and the motor 2 and the lifting device 14.

[0078] Table 1 Component Engagement Table

[0079]

[0080] Wherein: "▲" represents that the component is in the engaged state;

[0081] When the lifting device 14 lifts heavy objects, it is necessary to ensure that the heavy objects maintain a stable posture at a certain height and cannot fall due to insufficient power. Or when the heavy objects need to be moved during lifting, in this case, the main power output end cannot provide the lifting device 14 according to the rated output torque, so other power is needed for supplementation. The control method of the combined power system of the hybrid tractor described in the present invention includes the following steps:

[0082] Install a first pressure sensor at the outlet of the accumulator 12-4 to detect the pressure value P1 at the outlet of the accumulator 12-4, and install a second pressure sensor at the outlet of the variable pump 12-1 to detect the pressure value P0 at the outlet of the variable pump 12-1; determine the traveling state of the tractor through a speed sensor; obtain the height h of the lifted heavy object through a height sensor; determine the speed V of the lifted heavy object through a speed sensor h ; determine the vibration amplitude A of the lifted heavy object through a vibration sensor. Detecting the vibration amplitude A of the lifted heavy object can determine whether there is severe jitter during the lifting of the heavy object, so as to determine whether additional power is required.

[0083] The control system collects the SOC of the motor battery, the traveling speed v of the tractor, the pressure value P0 at the outlet of the variable pump 12-1, the pressure value P1 at the outlet of the accumulator 12-4, the height h of the lifted heavy object, the speed V of the lifted heavy object h and the vibration amplitude A of the lifted heavy object;

[0084] When the traveling speed v of the tractor = 0, that is, the tractor is in stationary operation. If the height h of the lifted heavy object ≤ the first set height h 0 , and the speed V of the lifted heavy object h is uniform, the control system controls a hydraulic transmission of the PTO output to be formed between the PTO output end 3-2 and the lifting device 14; if the height h of the lifted heavy object ≤ the first set height h 0 , and the speed V of the lifted heavy object h is uniform, the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls a compound hydraulic transmission of the PTO output to be formed between the PTO output end 3-2 and the lifting device 14; if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object h is uniform, the control system controls a mechanical transmission of the main power output to be formed between the main power output end 3-1 and the lifting device 14; if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object h changes with uniform acceleration, the control system controls a mechanical-hydraulic transmission I that combines the PTO output end 3-2 and the main power output end 3-1 with the lifting device 14; if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object hThe change is a uniform acceleration, and when the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls the PTO output end 3-2 and the main power output end 3-1 to form a combined mechanical-hydraulic transmission of PTO and main power with the lifting device 14. It should be noted that when the vibration amplitude A of the lifted heavy object is greater than the set value, the gravitational potential energy of the heavy object also increases as the rising height increases. The vibration of the heavy object during the rising process indicates that the torque output by the lift is approaching the critical value.

[0085] When the traveling speed v of the tractor is not equal to 0 and it is traveling at a low speed, that is, when the tractor is performing a lifting operation in a low-speed traveling state, since the action output by the main power output end 3-1 in the traveling state is less than 30% of the rated output, therefore, through the design of the number of teeth of the gears of the transmission system and the differential, the action output by the main power output end 3-1 in the traveling state is controlled to be 15% - 25% of the rated output, and the power is distributed through the design of the number of teeth of the gears of the transmission system and the differential. This is a conventional mechanical design, and the specific structure is not shown in the figure. The specific control is as follows:

[0086] If the height h of the lifted heavy object is less than or equal to the first set height h 0 , and the speed V of the lifted heavy object h is uniform, and SOC > the health state limit value SOC of the battery min at this time, the control system controls the motor 2 and the lifting device 14 to form a mechanical transmission output by the motor.

[0087] If the height h of the lifted heavy object is less than or equal to the first set height h 0 , and the speed V of the lifted heavy object h is uniform, and SOC < 1.5 * SOC min at this time, the control system controls the engine 1 and the motor 2 and the lifting device 14 to form a mechanical transmission output with auxiliary power of the motor.

[0088] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniform, and SOC > the health state limit value SOC of the battery min at this time, the control system controls the PTO output end 3-2 and the motor 2 and the lifting device 14 to form a combined mechanical-hydraulic transmission of PTO and motor.

[0089] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniform, and SOC > the health state limit value SOC of the battery min, when the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls the PTO output end 3-2, the motor 2 and the lifting device 14 to form a combined mechanical and hydraulic transmission two of the PTO and the motor.

[0090] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniform, and SOC < 1.5 * SOC min , when the vibration amplitude A of the lifted heavy object is greater than the set value, the control system controls the PTO output end 3-2, the motor 2 and the lifting device 14 to form a combined mechanical and hydraulic transmission three of the PTO and the motor.

[0091] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniformly accelerating, and SOC > SOC min When, the control system controls the engine 1, the motor 2 and the lifting device 14 to form a combined mechanical and hydraulic transmission one of the PTO, the main power and the motor.

[0092] If 1.5h 0 > the height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniformly accelerating, and SOC > SOC min , when the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls the engine 1, the motor 2 and the lifting device 14 to form a combined mechanical and hydraulic transmission two of the PTO, the main power and the motor. In this transmission system, if SOC < 1.5 * SOC min , the fourth clutch C can be controlled 4 14 to engage, and the auxiliary power output end 3-3 is used to assist in outputting power to make up for the motor 2 that is about to run out of power.

[0093] It should be understood that although this specification is described according to each embodiment, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0094] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the present invention, and they are not used to limit the protection scope of the present invention. Any equivalent embodiments or changes made without departing from the technical spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A compound power system for a hybrid tractor, comprising an engine (1), an electric motor (2) and a transmission system (3). The engine (1) and the electric motor (2) are respectively connected to the transmission system (3). The output end of the transmission system (3) is a main power output end (3-1) and a PTO output end (3-2). The main power output end (3-1) is used to connect to a differential (9), and the PTO output end (3-2) is used for external work. Characterized in that, it further comprises a hydraulic transmission device (12), a clutch assembly, a transmission device (8) and a lifting device (14). The PTO output end (3-2) is connected to the input end of the hydraulic transmission device (12). The output end of the hydraulic transmission device (12) is connected to the lifting device (14) through an intermediate shaft (17). The main power output end (3-1) is connected to the lifting device (14). The electric motor (2) is connected to the lifting device (14) through the transmission device (8). The output end of the transmission system (3) further comprises a secondary power output end (3-3), and the secondary power output end (3-3) is connected to the transmission device (8). By controlling the displacement ratio of the hydraulic transmission device (12) and selectively controlling the engagement of the clutch assembly, a continuously variable transmission ratio is provided between the PTO output end (3-2) and the lifting device (14), between the main power output end (3-1) or / and the electric motor (2) and the lifting device (14), between the PTO output end (3-2) and the main power output end (3-1) and the lifting device (14), between the PTO output end (3-2) and the electric motor (2) and the lifting device (14), and between the PTO output end (3-2), the main power output end (3-1) and the electric motor (2) and the lifting device (14). The hydraulic transmission device (12) includes a variable pump (12-1), a pump / motor mechanism (12-2), a solenoid directional valve V 1 (12-3), an accumulator (12-4), a solenoid directional valve V 2 (12-6) and a check valve (12-7); the input end of the variable pump (12-1) is connected to the PTO output end (3-2), the variable pump (12-1) is communicated with the pump / motor mechanism (12-2), and a solenoid directional valve V 1 (12-3) and a solenoid directional valve V 2 (12-6) are arranged in parallel between the variable pump (12-1) and the pump / motor mechanism (12-2); the outlet of the solenoid directional valve V 1 (12-3) is respectively communicated with the accumulator (12-4) and the fuel tank (12-5); the working pressure of the accumulator (12-4) is greater than the rated output pressure of the variable pump (12-1); the solenoid valve Sb1 of the solenoid directional valve V 1 (12-3) works to connect the accumulator (12-4) with the outlet of the variable pump (12-1), and connect the fuel tank (12-5) with the inlet of the variable pump (12-1); the solenoid valve Sb2 of the solenoid directional valve V 1 (12-3) works to connect the accumulator (12-4) with the outlet of the pump / motor mechanism (12-2), and connect the fuel tank (12-5) with the inlet of the pump / motor mechanism (12-2); a check valve (12-7) is installed at the outlet of the variable pump (12-1); The clutch assembly includes a first clutch C 1 (11), a second clutch C 2 (7), a third clutch C 3 (4), a fourth clutch C 4 (15) and a fifth clutch C 5 (16); the first clutch C 1 (11) is used to selectively connect the PTO output end (3-2) to the input end of the variable pump (12-1); the second clutch C 2 (7) is used to selectively connect the output end of the motor (2) to the transmission (8); the third clutch C 3 (4) is used to selectively connect the main power output end (3-1) to the intermediate shaft (17); the fourth clutch C 4 (15) is used to selectively connect the auxiliary power output end (3-3) to the transmission (8); the fifth clutch C 5 (16) is used to selectively connect the output end of the pump / motor mechanism (12-2) to the intermediate shaft (17).

2. The compound power system for a hybrid tractor according to claim 1, Characterized in that, By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the engagement of the clutch assembly, solenoid directional valve V 1 (12-3) and solenoid directional valve V 2 (12-6), multiple transmission modes are provided between the PTO output end (3-2) and the lifting device (14), between the main power output end (3-1) and the lifting device (14), between the motor (2) and the lifting device (14), between the PTO output end (3-2) and the main power output end (3-1) and the lifting device (14), between the motor (2) and the main power output end (3-1) and the lifting device (14), and between the PTO output end (3-2), the main power output end (3-1) and the motor (2) and the lifting device (14).

3. The compound power system for a hybrid tractor according to claim 2, Characterized in that, By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the engagement of the first clutch C 1 (11) and the fifth clutch C 5 (16), a hydraulic transmission of the PTO output between the PTO output end (3-2) and the lifting device (14) is provided; By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the engagement of the first clutch C 1 (11) and the fifth clutch C 5 (16), selectively controlling the solenoid valve Sb1 of the electromagnetic directional control valve V 1 (12-3) to operate, providing a compound hydraulic transmission of the PTO output between the PTO output end (3-2) and the lifting device (14); By selectively controlling the third clutch C 3 (4) to engage, providing a mechanical drive for the active power output between the active power output end (3-1) and the lifting device (14); By selectively controlling the engagement of the second clutch C 2 (7), a mechanical transmission of the motor output between the motor (2) and the lifting device (14) is provided.

4. The compound power system for a hybrid tractor according to claim 2, Characterized in that, By selectively controlling the second clutch C 2 (7) and the fourth clutch C 4 (15) to engage, a sub-power assist motor output mechanical transmission between the engine (1), the motor (2) and the lifting device (14) is provided; By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the engagement of the first clutch C 1 (11), the third clutch C 3 (4) and the fifth clutch C 5 (16), a mechanical-hydraulic transmission one with combined PTO and main power is provided between the PTO output end (3-2) and the main power output end (3-1) and the lifting device (14); By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the engagement of the first clutch C 1 (11), the third clutch C 3 (4) and the fifth clutch C 5 (16), controlling the solenoid valve Sb 1 (12-3) of the electromagnetic directional control valve V 1 to be energized, providing a mechanical-hydraulic transmission II that combines PTO and main power between the PTO output end (3-2) and the main power output end (3-1) and the lifting device (14).

5. The compound power system for a hybrid tractor according to claim 2, Characterized in that, By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the engagement of the first clutch C 1 (11), the second clutch C 2 (7) and the fifth clutch C 5 (16), a combined mechanical and hydraulic transmission of the PTO and the motor between the PTO output end (3-2) and the motor (2) and the lifting device (14) is provided; By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the engagement of the first clutch C 1 (11), the second clutch C 2 (7) and the fifth clutch C 5 (16), and controlling the solenoid valve Sb 1 of the solenoid directional control valve V 1 (12-3) to be energized, providing a combined mechanical-hydraulic transmission II of PTO and motor between the PTO output end (3-2) and the motor (2) and the lifting device (14) By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the first clutch C 1 (11) Second clutch C 2 (7) Fourth clutch C 4 (15) and the fifth clutch C 5 (16) Engage and control the solenoid valve V 1 (12-3) Solenoid valve Sb 1 Power is obtained to provide a mechanical hydraulic transmission three of the PTO and motor compound between the PTO output terminal (3-2) and the motor (2) and the lifting device (14).

6. The compound power system for a hybrid tractor according to claim 2, Characterized in that, By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the first clutch C 1 (11), the second clutch C 2 (7), the third clutch C 3 (4) and the fifth clutch C 5 (16) are engaged to provide a mechanical hydraulic transmission I that combines PTO, main power, and motor between the PTO output (3-2), the engine (1), the motor (2), and the lifting device (14). By adjusting the displacement ratio of the hydraulic transmission device (12) and selectively controlling the first clutch C 1 (11) Second clutch C 2 (7) Third clutch C 3 (4) and the fifth clutch C 5 (16) Engage and control the solenoid valve V 1 (12-3) Solenoid valve Sb 1 Power is obtained to provide a mechanical hydraulic transmission 2 of the PTO, main power and motor compound between the PTO output terminal (3-2), the engine (1) and the motor (2) and the lifting device (14).

7. The compound power system for a hybrid tractor according to claim 1, Characterized in that, By engaging the fifth clutch C 5 (16) and controlling the solenoid-operated directional valve V 1 the solenoid valve Sb of (12-3) 2 is energized to provide potential energy recovery drive between the lifting device (14) and the accumulator (12-4).

8. A control method for the compound power system of a hybrid tractor according to claim 2, Characterized in that, comprises the following steps: Obtain the pressure value P1 at the outlet of the accumulator (12-4) through the first pressure sensor; obtain the pressure value P0 at the outlet of the variable pump (12-1) through the second pressure sensor; obtain the traveling state of the tractor through the first speed sensor; obtain the height h of the lifted heavy object through the height sensor; determine the speed V of the lifted heavy object through the second speed sensor h ; determine the vibration amplitude A of the lifted heavy object through the vibration sensor; The control system collects the SOC of the motor battery, the traveling speed v of the tractor, the pressure value P0 at the outlet of the variable pump (12-1), the pressure value P1 at the outlet of the accumulator (12-4), the height h of the lifted heavy object, the speed V of the lifted heavy object h and the vibration amplitude A of the lifted heavy object; When the traveling speed v of the tractor is 0, if the height h of the lifted heavy object ≤ the first set height h 0 , and the speed V of the lifted heavy object h is uniform, the control system controls a hydraulic drive of the PTO output between the PTO output end (3-2) and the lifting device (14); if the height h of the lifted heavy object ≤ the first set height h 0 , and the speed V of the lifted heavy object h is uniform, the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls a compound hydraulic drive of the PTO output between the PTO output end (3-2) and the lifting device (14); if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object h is uniform, the control system controls a mechanical drive of the main power output between the main power output end (3-1) and the lifting device (14); if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object h changes with a uniform acceleration, the control system controls a mechanical-hydraulic drive one that combines the PTO and the main power between the PTO output end (3-2) and the main power output end (3-1) and the lifting device (14); if the maximum lifting height h max > the height h of the lifted heavy object > 1.5h 0 , and the speed V of the lifted heavy object h changes with a uniform acceleration, and the vibration amplitude A of the lifted heavy object is greater than the set value and P1 > P0, the control system controls a mechanical-hydraulic drive two that combines the PTO and the main power between the PTO output end (3-2) and the main power output end (3-1) and the lifting device (14); When the traveling speed v of the tractor is not equal to 0, if the height h of the lifted heavy object is less than or equal to the first set height h 0 , and the speed V of the lifted heavy object h is uniform, and SOC > the health state limit value SOC of the battery min , the control system controls the formation of a motor output mechanical drive between the motor (2) and the lifting device (14); If the height h for lifting the heavy object satisfies h ≤ the first set height h 0 , and the speed V of lifting the heavy object h is uniform, and SOC < 1.5 * SOC min , the control system controls the engine (1) and the motor (2) to form a sub-power auxiliary motor output mechanical transmission with the lifting device (14); If 1.5h 0 > the height h of lifting the heavy object > h 0 , and the speed V of lifting the heavy object h is uniform, and SOC > the limit value SOC of the battery health state min When, the control system controls that a mechanical hydraulic transmission one combined by the PTO output end (3-2) and the motor (2) and the lifting device (14) is formed; If 1.5 h 0 > The height h of lifting the heavy object > h 0 , and the speed V of lifting the heavy object h is uniform, and SOC > the limit value of the battery health state SOC min , when the vibration amplitude A of lifting the heavy object is greater than the set value and P1 > P0, the control system controls that a mechanical-hydraulic transmission two composed of the PTO output end (3-2) and the motor (2) and the lifting device (14) is formed; If 1.5 h 0 > The height h for lifting the heavy object > h 0 , and the speed V of lifting the heavy object h is uniform, and SOC < 1.5 * SOC min , when the vibration amplitude A of lifting the heavy object is greater than the set value, the control system controls that a mechanical hydraulic transmission three with a combined PTO and motor is formed between the PTO output end (3-2) and the motor (2) and the lifting device (14); If 1.5 h 0 > The height h of the lifted heavy object > h 0 , and the speed V of the lifted heavy object h is uniformly accelerated, and SOC > SOC min When, the control system controls that a mechanical hydraulic transmission one which is a compound of PTO, main power and motor is formed between the engine (1), the motor (2) and the lifting device (14); If 1.5 h 0 > The height h of lifting the heavy object > h 0 , and the speed V of lifting the heavy object h is uniformly accelerated, and SOC > SOC min , when the vibration amplitude A of lifting the heavy object is greater than the set value and P1 > P0, the control system controls the engine (1) and the motor (2) to form a combined mechanical hydraulic transmission of PTO, main power and motor with the lifting device (14).

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