GB2618662A

GB2618662A - Energy recovery and recycling integrated system

Info

Publication number: GB2618662A
Application number: GB2303647.8A
Authority: GB
Inventors: Li Jiansong; Ji Zhi; Sun Jinhai; Li Shaohui; Zhou Bo
Original assignee: Xuzhou College of Industrial Technology
Current assignee: Xuzhou College of Industrial Technology
Priority date: 2022-03-15
Filing date: 2023-03-13
Publication date: 2023-11-15
Anticipated expiration: 2043-03-13
Also published as: GB202303647D0; CN114622609A; GB2618662B; CN114622609B

Abstract

A hydraulic circuit energy recovery system, the circuit being pressurised by a pump 1 driven by an engine 6, a main directional control valve 3 directing fluid into a three-chamber hydraulic cylinder 4. In motoring mode, hydraulic pump-motor 12 converts fluid pressure from cylinder 4 into kinetic energy of flywheel 8. In pumping mode, hydraulic pump-motor 12 pumps fluid from oil tank 5 to pressurise accumulator 7. Fluid in accumulator 7 can (i) drive a second hydraulic motor 14 for starting the engine 6 via a clutch 15 and gears 16, 17, or (ii) reduce the pressure differential by increasing supply pressure to the pump 1. An auxiliary direction control valve 9 controls fluid distribution between the hydraulic pump-motor 12, accumulator 7, hydraulic motor 14 and the supply to the pump 1. The main 3 and auxiliary direction control valve 9 may be four-way three-position 4/3 solenoid valve. Switching valve 13 may be 2/2 solenoid valve and switching valve 19 a 3/2 solenoid valve.

Description

ENERGY RECOVERY AND RECYCLING INTEGRATED SYSTEM

TECHNICAL FIELD

100011 The present disclosure belongs to the technical field of hydraulic control, and specifically relates to an energy recovery and recycling integrated system.

BACKGROUND

[0002] As shown in FIG. 1, in the prior art, a boom subsystem in an excavator usually includes a boom 100, a turntable 200 and a boom hydraulic cylinder 4. The barrel of the boom hydraulic cylinder 4 is hinged to the turntable 200, and the rod of the boom hydraulic cylinder 4 is hinged to the middle part of the boom 100. When the boom hydraulic cylinder extends or retracts, the boom can be driven to move up or down. During the working process of the excavator, the boom moves up and down frequently, and a large amount of potential energy can be released in the descending process due to heavy working device and high load. FIG. 2 is a simplified schematic diagram of an excavator boom hydraulic system in the prior art. According to FIG. 1 and FIG. 2, most of the potential energy is consumed at the orifice of the main directional control valve 3 and converted into heat, resulting in energy waste and system heating. At the same time, the service life of the hydraulic component is also reduced due to the high temperature of fluid.

[0003] With the rapid development of social economy, the problem of energy shortage is becoming more and more serious. How to reduce energy consumption is an urgent problem to be solved at present. At the same time, the energy efficiency is one of the key parameters in the market competition of hydraulic excavators, so it is urgent to study the energy-saving technology of hydraulic excavators.

100041 At present, the system configured to recover the potential energy of the excavator boom has a single function, the energy-saving effect is not ideal, and energy is still wasted. Meanwhile, the energy utilization mode is not flexible.

SUMMARY

[0005] In view of the problems existing in the prior art, the present disclosure provides an energy recovery and recycling integrated system. The system can not only effectively recover the potential energy of the boom, but also avoid energy waste and realize the process of energy recycling in various ways.

100061 In order to achieve the purpose, the present disclosure provides an energy recovery and recycling integrated system. The system includes an engine, a hydraulic pump, a first check valve, a main directional control valve, a boom hydraulic cylinder, a joystick, a third check valve, a second gear, a first gear, a second clutch, a hydraulic motor, an auxiliary directional control valve, an accumulator, a hydraulic pump motor, a first switching valve, a second switching valve, a third switching valve, a second check valve, a fourth check valve, a first clutch, a flywheel and a controller.

[0007] The engine is coaxially connected with the hydraulic pump. The port P of the hydraulic pump is connected with the inlet A of the first check valve. The outlet B of the first check valve is connected with the port P of the main directional control valve through a pipeline. The port A of the main directional control valve is connected with the port B of the boom hydraulic cylinder through a pipeline, and the port B of the main directional control valve is connected with the port A of the boom hydraulic cylinder through a pipeline. The port T of the main directional control valve is connected with the oil tank through a pipeline.

[0008] The outlet B of the third check valve is connected with the port S of the hydraulic pump through a pipeline, and the inlet A of the third check valve is connected with the oil tank through a pipeline.

[0009] The boom hydraulic cylinder is a three-chamber hydraulic cylinder, the barrel of the boom hydraulic cylinder is hinged with a turntable, and the rod end of the boom hydraulic cylinder is hinged with the middle part of the boom 100101 The second gear is coaxially connected with the engine. The first gear is meshed with the second gear, and the shaft of the first gear is connected with the shaft of the hydraulic motor through the second clutch.

[0011] The port T of the hydraulic motor is connected with the oil tank through a pipeline, and the port P of the hydraulic motor is connected with the port T of the second switching valve through a pipeline.

100121 The port P of the second switching valve is connected with the outlet B of the third check valve, and the port A of the second switching valve is connected with the port T of the auxiliary directional control valve.

100131 The port P of the auxiliary directional control valve is simultaneously connected with the port P of the hydraulic pump motor and the port P of the first switching valve through pipelines, the port B of the auxiliary directional control valve is connected with the accumulator through a pipeline, and the port A of the auxiliary directional control valve is blocked.

[0014] The hydraulic pump motor is connected with the shaft of the flywheel through the first clutch, and the port S of the hydraulic pump motor is connected with the oil tank through a pipeline.

[0015] The port A of the first switching valve is connected with the port C of the boom hydraulic cylinder and the outlet B of the second check valve through pipelines, and the inlet A of the second check valve is connected with the oil tank through a pipeline.

[0016] The port A of the third switching valve is connected with the port A of the fourth check valve, the port B is connected with the port B of the main directional control valve, and the port P is connected with the port C of the boom hydraulic cylinder.

100171 The port B of the fourth check valve is connected with the port A of the main directional control valve.

[0018] The controller is respectively connected with the joystick, the engine, the main directional control valve, the auxiliary directional control valve, the first clutch, the second clutch, the first switching valve, the second switching valve, the third switching valve, the hydraulic pump motor and the hydraulic motor.

100191 As a preference, the controller is a programmable logic controller (PLC).

100201 As a preference, the first switching valve is a two-position two-way solenoid-actuated directional control valve, and works in the right position when de-energized and in the left position when energized. When the first switching valve works in the right position, the oil passage between the port P and the port A is disconnected; and when the first switching valve works in the left position, the oil passage between the port P and the port A is connected [0021] As a preference, the second switching valve is a two-position three-way solenoid-actuated directional control valve, and works in the left position when de-energized or in the right position when energized When the second switching valve works in the left position, the oil passage between the port P and the port A is disconnected, and the oil passage between the port T and the port A is connected; and when the second switching valve works in the right position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port A is disconnected.

[0022] As a preference, the main directional control valve is a three-position four-way solenoid-actuated directional control valve, and works in the left position when the electromagnet Y lb of the main directional control valve is energized. The main directional control valve works in the right position when the electromagnet Y1 a of the main directional control valve is energized. The main directional control valve works in the center position when the electromagnets Yla and Ylb of the main directional control valve are de-energized. When the main directional control valve works in the left position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port B is connected; when the main directional control valve works in the right position, the oil passage between the port P and the port B is connected, and the oil passage between the port T and the port A is connected; and when the main directional control valve works in the center position, the port P, the port A, the port T and the port B are all blocked and are not connected with one another.

[0023] As a preference, the auxiliary directional control valve is a three-position four-way solenoid-actuated directional control valve, and works in the left position when the electromagnet Y3b of the auxiliary directional control valve is energized. The auxiliary directional control valve works in the right position when the electromagnet Y3a of the auxiliary directional control valve is energized. The auxiliary directional control valve works in the center position when the two electromagnets of the auxiliary directional control valve are de-energized. When the auxiliary directional control valve works in the right position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port B is connected; when the auxiliary directional control valve works in the left position, the oil passage between the port P and the port B is connected, and the oil passage between the port T and the port A is connected; and when the auxiliary directional control valve works in the center position, the port P, the port A, the port T and the port B are blocked respectively, and are not connected with one another.

[0024] In the system, the boom hydraulic cylinder is a three-chamber hydraulic cylinder, and the third chamber 4c of the boom hydraulic cylinder is connected with the port P of the hydraulic pump motor through the first switching valve, and the flywheel is used as the energy storage element, so that the hydraulic pump motor can recover the energy of pressurized fluid in the boom descending process and store the energy in the flywheel. That means the waste of energy in the boom descending process is effectively avoided. Meanwhile, when the boom ascends, the energy stored in the flywheel can be recycled to drive the boom to go up. The port P of the auxiliary directional control valve is connected to the port P of the hydraulic pump motor, so that when there is still some residual energy in the flywheel after the engine is turned off, the residual energy in the flywheel can be converted into pressure energy and stored in the accumulator for subsequent use by controlling the auxiliary directional control valve to work in the left position, so that the waste of the energy is effectively avoided. The port T of the auxiliary directional control valve is connected with either the port S of the hydraulic pump or the port P of the hydraulic motor through the second switching valve, so that the energy stored in the accumulator can be recycled in various ways by controlling the second switching valve. On the one hand, the oil can directly flow to the port S of the hydraulic pump, so that the pressure of the oil suction port of the hydraulic pump is increased, the pressure difference between the port P and the port S can be reduced, the torque demand on the engine is reduced, and a certain energy-saving effect is achieved. On the other hand, the oil can flow back to the oil tank through the hydraulic motor. The hydraulic motor can drive the first gear through the second clutch, and the second gear coaxially connected with the engine is meshed with the first gear. Therefore, in this process, the engine can be restarted through the driving of the hydraulic motor, thus the system is beneficial to prolonging the service lives of the battery and the starting motor, and the restart of the engine can be realized under the condition that the battery is low in power. The system can not only save energy efficiently, but also avoid the waste of energy. Moreover, the recycling process of energy can be realized in many ways, and the power demand for the engine can be reduced, so that a smaller engine is selected in the system, and the input cost of the engine is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

100251 FIG. 1 is an assembly diagram of the boom and the hydraulic cylinder of common construction machinery; [0026] FIG. 2 is a simplified schematic diagram of an excavator boom hydraulic system in the

prior art and

[0027] FIG. 3 is a hydraulic schematic diagram of the present disclosure.

[0028] Reference signs: 1, hydraulic pump; 2, first check valve; 3, main directional control valve; 4, boom hydraulic cylinder; 4a, non-rod chamber; 4b, rod chamber; 4c, third chamber; 5, oil tank; 6, engine; 7, accumulator; 8, flywheel; 9, auxiliary directional control valve; 10, second check valve; 11, first clutch; 12, hydraulic pump motor; 13, first switching valve; 14, hydraulic motor; 15, second clutch; 16, first gear; 17, second gear; 18, third check valve; 19, second switching valve; 20, third switching valve; 21, fourth check valve; 100, boom; and 200, turntable.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present disclosure is described in further detail below.

[0030] As shown in FIG. 1, a boom subsystem in the prior art usually includes a boom 100, a turntable 200 and a boom hydraulic cylinder 4. The barrel of the boom hydraulic cylinder 4 is hinged to the turntable 200, and the rod of the boom hydraulic cylinder 4 is hinged to the middle part of the boom 100. When the boom hydraulic cylinder extends or retracts, the boom can be driven to move up or down.

[0031] FIG. 2 is a simplified schematic diagram of an excavator boom hydraulic system in the prior art. The boom hydraulic cylinder system generally includes an engine 6, a hydraulic pump I, an oil tank 5, a first check valve 2, a main directional control valve 3 and a boom hydraulic cylinder 4. The engine 6 drives the hydraulic pump 1 to provide pressure energy for the system. The first check valve 2 is configured to prevent any oil from flowing backwards. The oil tank 5 provides storage space for the fluid in the system. The main directional control valve 3 in the figure is a three-position four-way directional control valve, and also may be a six-way directional control valve in a real hydraulic system. The operating mode of the main directional control valve 3 may also be manually operated, hydraulically pilot-actuated or other modes. The function of the main directional control valve 3 is to control the flow direction and flow rate of fluid, then control the movement of the boom hydraulic cylinder 4, and finally control the boom 100.

[0032] As shown in FIG. 3, an energy recovery and recycling integrated system includes an engine 6, a hydraulic pump 1, a first check valve 2, a main directional control valve 3, a boom hydraulic cylinder 4, a joystick (unshown in the figure), a third check valve 18, a second gear 17, a first gear 16, a second clutch 15, a hydraulic motor 14, an auxiliary directional control valve 9, an accumulator 7, a hydraulic pump motor 12, a first switching valve 13, a second switching valve 19, a third switching valve 20, a second check valve 10, a fourth check valve 21, a first clutch 11, a flywheel 8 and a controller.

[0033] The joystick is controlled by an operator and configured to send out a control signal. 100341 The engine 6 is coaxially connected with the hydraulic pump 1. The port P of the hydraulic pump 1 is connected with the inlet A of the first check valve 2. The outlet B of the first check valve 2 is connected with the port P of the main directional control valve 3 through a pipeline. The port A of the main directional control valve 3 is connected with the port B of the boom hydraulic cylinder 4 through a pipeline, and the port B of the main directional control valve 3 is connected with the port A of the boom hydraulic cylinder 4 through a pipeline. The port T of the main directional control valve 3 is connected with the oil tank 5 through a pipeline. [0035] The first check valve 2 ensures the one-way flow of fluid to the main directional control valve 3, and reversely prevents any flow. The oil tank 5 provides storage space for the oil in the system.

[0036] The outlet B of the third check valve 18 is connected with the port S of the hydraulic pump 1 through a pipeline, and the inlet A of the third check valve 18 is connected with the oil tank 5 through a pipeline.

[0037] The boom hydraulic cylinder 4 is a three-chamber hydraulic cylinder, the barrel of the boom hydraulic cylinder 4 is hinged with the turntable 200, and the rod end of the boom hydraulic cylinder 4 is hinged with the middle part of the boom 100. The port A, the port B and the port C are formed in the barrel of the boom hydraulic cylinder 4 The interior of the barrel of the boom hydraulic cylinder 4 is provided with a non-rod chamber 4a, a rod chamber 4b and a third chamber 4c, wherein the port A communicates with the non-rod chamber 4a, the port B communicates with the rod chamber 4b, and the port C communicates with the third chamber 4c. [0038] The second gear 17 is coaxially connected with the engine 6. The first gear 16 is meshed with the second gear 17, and the shaft of the first gear 16 is connected with the shaft of the hydraulic motor 14 through the second clutch 15.

100391 The port T of the hydraulic motor 14 is connected with the oil tank 5 through a pipeline, and the port P of the hydraulic motor 14 is connected with the port T of the second switching valve 19 through a pipeline.

100401 The port P of the second switching valve 19 is connected with the outlet B of the third check valve 18, and the port A of the second switching valve 19 is connected with the port T of the auxiliary directional control valve 9.

[0041] The port P of the auxiliary directional control valve 9 is simultaneously connected with the port P of the hydraulic pump motor 12 and the port P of the first switching valve 13 through pipelines, the port B of the auxiliary directional control valve 9 is connected with the accumulator 7 through a pipeline, and the port A of the auxiliary directional control valve 9 is blocked.

100421 Energy status in the accumulator 7 is collected in real time by a pressure sensor connected to the accumulator 7 and transmitted to the controller in real time.

[0043] The hydraulic pump motor 12 is connected with the shaft of the flywheel 8 through the first clutch 11, and the port S of the hydraulic pump motor 12 is connected with the oil tank 5 through a pipeline The first clutch 11 is configured to connect or disconnect the flywheel 8 and the hydraulic pump motor 12, and the action of the first clutch 11 is controlled by the controller. The flywheel 8 has a large moment of inertia and can store energy in the form of kinetic energy. [0044] The port A of the first switching valve 13 is connected with the port C of the boom hydraulic cylinder 4 and the outlet B of the second check valve 10 through pipelines, and the inlet A of the second check valve 10 is connected with the oil tank 5 through a pipeline 100451 By arranging the second check valve 10, the oil in the oil tank 5 is replenished into the third chamber 4c of the boom hydraulic cylinder 4 when the pressure in the third chamber of the boom hydraulic cylinder 4 is lower than that in the oil tank 5for some reasons.

100461 The port A of the third switching valve 20is connected with the port A of the fourth check valve 21, the port B is connected with the port B of the main directional control valve 3, and the port P is connected with the port C of the boom hydraulic cylinder 4.

[0047] The port B of the fourth check valve 21 is connected with the port A of the main directional control valve 3 [0048] The controller is respectively connected with the joystick, the engine 6, the main directional control valve 3, the auxiliary directional control valve 9, the first clutch 11, the second clutch 15, the first switching valve 13, the second switching valve 19, the third switching valve 20, the hydraulic pump motor 12 and the hydraulic motor 14.

100491 In order to facilitate the change of the transmission ratio, a transmission is installed between the hydraulic pump motor 12 and the clutch 11, and is connected with the controller. [0050] As a preference, the controller is a programmable logic controller (PLC).

[0051] As a preference, the first switching valve 13 is a two-position two-way solenoid-actuated directional control valve, and works in the right position when de-energized or in the left position when energized. When the first switching valve 13 works in the right position, the oil passage between the port P and the port A is disconnected, and when the first switching valve 13 works in the left position, the oil passage between the port P and the port A is connected.

[0052] As a preference, the second switching valve 19 is a two-position three-way solenoid-actuated directional control valve, and works in the left position when de-energized or in the right position when energized. When the second switching valve 19 works in the left position, the oil passage between the port P and the port A is disconnected, and the oil passage between the port T and the port A is connected; and when the second switching valve 19 works in the right position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port A is disconnected.

100531 As a preference, the third switching valve 20 is a three-position three-way solenoid-actuated directional control valve with two electromagnets Y5a and Y5b. When the two electromagnets are not energized, the valve works in the center position, and the three ports are closed and disconnected from each other. When only the electromagnet Y5b is energized, the valve works in the left position, the port P is connected with port B, and the port A is closed. When only the electromagnet Yla is energized, the valve works in the right position, the port P is connected with port A, and the port B is closed.

[0054] As a preference, the main directional control valve 3 is a three-position four-way solenoid-actuated directional control valve, and works in the left position when the electromagnet Y lb of the main directional control valve 3 is energized, or in the right position when the electromagnet Yla of the main directional control valve 3 is energized. The main directional control valve 3 works in the center position when the two electromagnets Yla and Ylb of the main directional control valve 3 are de-energized. When the main directional control valve 3 works in the right position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port B is connected; when the main directional control valve 3 works in the left position, the oil passage between the port P and the port B is connected, and the oil passage between the port T and the port A is connected; and when the main directional control valve 3 works in the center position, the port P, the port A, the port T and the port B are all blocked and not connected with one another.

[0055] As a preference, the auxiliary directional control valve 9 is a three-position four-way solenoid-actuated directional control valve, and works in the left position when the electromagnet Y3b of the auxiliary directional control valve 9 is energized, or in the right position when the electromagnet Y3a of the auxiliary directional control valve 9 is energized. The auxiliary directional control valve 9 works in the center position when the two electromagnets Y3a and Y3b of the auxiliary directional control valve 9 are de-energized. When the auxiliary directional control valve 9 works in the right position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port B is connected; when the auxiliary directional control valve 9 works in the left position, the oil passage between the port P and the port B is connected, and the oil passage between the port T and the port A is connected; and when the auxiliary directional control valve 9 works in the center position, the port P, the port A, the port T arid the port B are all blocked and not connected with one another.

[0056] As a preference, on the energy recycling transmission chain, in order to match the speeds of the flywheel 8 arid the hydraulic pump motor 12, a transmission further can be selectively installed between the clutch 11 and the hydraulic pump motor 12.

[0057] In the system, the boom hydraulic cylinder is a three-chamber hydraulic cylinder, and the third chamber 4c of the boom hydraulic cylinder is connected with the port P of the hydraulic pump motor through the first switching valve, and the flywheel is used as the energy storage element, so that the hydraulic pump motor can recover the energy of pressurized fluid in the boom descending process and store the energy in the flywheel. That means the waste of energy in the boom descending process is effectively avoided. Meanwhile, when the boom ascends, the energy stored in the flywheel can be recycled to drive the boom to go up. The port P of the auxiliary directional control valve is connected to the port P of the hydraulic pump motor, so that when there is still some residual energy in the flywheel after the engine is turned off, the residual energy in the flywheel can be converted into pressure energy and stored in the accumulator for subsequent use by controlling the auxiliary directional control valve to work in the left position, so that the waste of the energy is effectively avoided. The port T of the auxiliary directional control valve is respectively connected with either the port S of the hydraulic pump or the port P of the hydraulic motor through the second switching valve, so that the energy stored in the accumulator can be recycled in various ways by controlling the second switching valve. On the one hand, the oil can directly flow to the port S of the hydraulic pump, so that the pressure of the oil suction port of the hydraulic pump is increased, the pressure difference between the port P and the port S can be reduced, the torque demand on the engine is reduced, and a certain energy-saving effect is achieved. On the other hand, the oil can flow back to the oil tank through the hydraulic motor. The hydraulic motor can drive the first gear through the second clutch, and the second gear coaxially connected with the engine is meshed with the first gear. Therefore, in this process, the engine can be restarted through the driving of the hydraulic motor, thus the system is beneficial to prolonging the service lives of the battery and the starting motor, and the restart of the engine can be realized under the condition that the battery is low in power. The system can not only save energy efficiently, but also avoid the waste of energy. Moreover, the recycling process of energy can be realized in many ways, and the power demand for the engine can be reduced, so that a smaller engine is selected in the system, and the input cost of the engine is reduced.

[0058] The working principle is as follows.

[0059] With reference to FIG. 3, the working principle of the present disclosure is further described as follows.

[0060] Firstly, the boom descending process (boom potential energy recovery).

[0061] When the boom 100 needs to descend, the operator sends a boom descending signal through the joystick. When the controller receives the boom descending signal, the electromagnet Y lb of the main directional control valve 3 is energized, the electromagnet Y2 of the first switching valve 13 is energized, and the first clutch 11 is energized. With reference to FIG. 3, the fluid discharged from the hydraulic pump 1 enters the rod chamber 4b of the boom hydraulic cylinder through the first check valve 2, the port P to the port A of the main directional control valve 3 and the port B of the boom hydraulic cylinder. Due to the loads such as the boom 100 acting on the three-chamber hydraulic cylinder, the pressure of the rod chamber of the boom hydraulic cylinder is relatively low. At the same time, the oil pressure in the non-rod chamber 4a of the boom hydraulic cylinder is also very low. The third chamber 4c of the boom hydraulic cylinder is connected with the hydraulic pump motor 12 through the first switching valve 13, and the internal pressure is relatively high, so almost all the loads are supported by the fluid in the third chamber 4c. The fluid in the non-rod chamber 4a of the boom hydraulic cylinder is discharged through the port A and flows back to the oil tank 5 through the port B to the port T of the main directional control valve 3. The pressurized fluid in the third chamber 4c flows into the port P of the hydraulic motor 12 through the port C, and the port A to the port P of the first switching valve 13, and then flows back to the oil tank 5 through the port S. At this time, the hydraulic pump motor 12 works in the motoring mode, outputs mechanical energy, and drives the flywheel 8 to accelerate through the transmission (if there be) and the first clutch 11. Therefore, boom potential energy is converted into the mechanical energy of the flywheel 8. In this process, the speed of the boom hydraulic cylinder can be adjusted by reasonably controlling the displacement of the hydraulic pump motor 12. Most of the pressure energy of the high-pressure fluid discharged by the boom hydraulic cylinder is converted into the mechanical energy of the flywheel 8 by the hydraulic pump motor 12, and very few energy is consumed at the orifice of the main directional control valve 3.

[0062] To stop the boom 100, all electromagnets and clutches 11 should be de-energized. Since there is energy in the flywheel 8, the flywheel will gradually slow down due to external resistance (such as friction of bearings and air friction), that is, the energy will gradually dissipate. If the time is long enough, the kinetic energy of the flywheel 8 may be totally lost.

[0063] In this mode, if necessary, the electromagnet Y5a of the third switching valve 20 is energized, the rod chamber 4b of the boom hydraulic cylinder is connected with the third chamber 4c. Part of the fluid in the third chamber 4c flows into the rod chamber 4b through port P to port B of the third switching valve 20, and port A to port B of the fourth check valve. Hence, the working pressure of hydraulic motor 12 is increased under the condition that the working principle of boom lowering is unchanged. Since the working pressure is relatively low when the boom is lowered, this design will improve the working efficiency of the hydraulic system and thus the efficiency of energy recovery.

[0064] Secondly, the boom ascending process (energy recycling).

[0065] When the boom 100 ascends, the operator sends out a boom ascending signal through the joystick. When the controller receives the boom ascending signal, the electromagnet Yla of the main directional control valve 3 is energized, and the fluid of the hydraulic pump 1 enters the non-rod chamber 4a of the boom hydraulic cylinder through the first check valve 2, the port P to the port B of the main directional control valve 3 and the port A of the boom hydraulic cylinder.

The fluid in the rod chamber 4b of the boom hydraulic cylinder flows back to the oil tank 5 through the port B and the port A to the port T of the main directional control valve 3. At the same time, the electromagnet Y2 of the first switching valve 13 is energized, and the first clutch 11 is energized for attraction. The flywheel 8 drives the hydraulic pump motor 12 to pump fluid. When the hydraulic pump motor 12 works in the pumping mode, the fluid is sucked from the oil tank 5 and discharged from the port P, and passes through the port P to the port A of the first switching valve 13 and the port C of the three-chamber hydraulic cylinder to enter the third chamber 4c of the boom hydraulic cylinder. Therefore, the kinetic energy of the flywheel 8 is recycled to drive the ascending of the boom 100, thus the power demand of the system on the engine 6 is reduced. At this stage, the boom hydraulic cylinder extends and the boom 100 ascends.

[0066] By reasonably controlling the displacement of the hydraulic pump motor 12, the energy of the flywheel 8 can be fully utilized.

100671 To stop the boom 100 all electromagnets and clutches are de-energized.

100681 In this mode, if necessary, the electromagnet Y5b of the third switching valve 20 is energized, the non-rod chamber 4a and the third chamber 4c of the boom hydraulic cylinder are connected. Under the condition that the working principle of the boom lifting is unchanged, the effective working area of the boom hydraulic cylinder is increased, and the bearing capacity of the boom is improved. In some special working conditions, such as rescue or lifting, greater driving force can be obtained.

[0069] Thirdly, the residual energy transfer mode.

100701 When the engine is turned off, if there is some residual energy in flywheel 8, this function will be activated.

[0071] When residual energy needs to be transferred, the operator sends a residual energy transfer signal through the joystick. When the controller receives the residual energy transfer signal, the controller controls the electromagnet Y3b of the auxiliary directional control valve 9 to be energized, and controls the first clutch 11 to be energized. The flywheel 8 drives the hydraulic pump motor 12 to rotate. When the hydraulic pump motor 12 works in the pumping mode, the oil is sucked from the oil tank 5 and discharged from the port P, and passes through the port P to the port B of the auxiliary directional control valve 9 to charge the accumulator 7. When the energy in the flywheel 8 is fully released, the electromagnet Y3b of the auxiliary directional control valve 9 and the first clutch 11 are de-energized. In this process, in order to get more energy, the displacement of the hydraulic pump motor should be controlled to ensure that the hydraulic pump motor 12 works in a high-efficiency area. Thus, the conversion of the kinetic energy of the flywheel 8 to the pressure energy of the accumulator 7 is realized. The working time of this mode is very short and cannot affect the normal shutdown of the excavator.

[0072] This function can be automatically achieved by the controller.

[0073] Fourthly, the recycling of energy in the accumulator.

100741 When the boom needs to ascend in the system, the energy in the accumulator 7 can be utilized. Thus, the problems that the energy in the flywheel 8 may be wasted after the excavator has no action for a long time and the engine is turned off are avoided, and the energy-saving effect of the system is further improved.

[0075] When the engine 6 needs to be restarted, if there is enough energy in the accumulator 7, the energy can be utilized in the following two ways.

100761 In the first way, the controller controls the electromagnet Y3a of the auxiliary directional control valve 9 to be energized, and the second clutch 15 to be energized, and keep the second switching valve 19 de-energized. The pressurized fluid in the accumulator 7 flows to the port P of the hydraulic motor 14 through the port B to the port T of the auxiliary directional control valve 9, and the port A to the port T of the second switching valve 19, and then flows back to the oil tank 5. The hydraulic motor 14 drives the first gear 16 through the second clutch 15 and further drives the second gear 17 to restart the engine 6. Thus, the recycling of the energy in the accumulator 7 is realized, and the conventional engine starting system is avoided from starting with the battery and the starting motor. This design is beneficial to prolonging the service lives of the battery and the starting motor, and can restart the engine under special circumstances (such as a battery with low power).

100771 In the second way, the controller controls the electromagnet Y3a of the auxiliary directional control valve 9 to be energized and the second switching valve 19 to be energized. The pressurized fluid in the accumulator 7 flows to the suction port S of the hydraulic pump 1 through the port B to the port T of the auxiliary directional control valve 9, and the port A to the port P of the second switching valve 19. The third check valve 18 is installed between the hydraulic pump 1 and the oil tank 5, so the fluid cannot flow back to the oil tank 5. At this time, the pressure of the suction port of the hydraulic pump 1 is increased, and the pressure difference between the port P and the port S is reduced, so the torque demand on the engine 6 is reduced, and a certain energy-saving effect is achieved. Thus, the problem that the energy in the flywheel 8 will be wasted when the excavator has no action for a long time or the engine is turned off is avoided, and the energy-saving effect of the system is further improved.

Claims

WHAT IS CLAIMED IS: 1. An energy recovery and recycling integrated system, comprising an engine (6), a hydraulic pump (1), a first check valve (2), a main directional control valve (3), a boom hydraulic cylinder (4) and a joystick, wherein the engine (6) is coaxially connected with the hydraulic pump (1), the port P of the hydraulic pump (1) is connected with the inlet A of the first check valve (2), the outlet B of the first check valve (2) is connected with the port P of the main directional control valve (3) through a pipeline, the port A of the main directional control valve (3) is connected with the port B of the boom hydraulic cylinder (4) through a pipeline, the port B of the main directional control valve (3) is respectively connected with the port A of the boom hydraulic cylinder (4) through a pipeline, and the port T of the main directional control valve (3) is connected with an oil tank (5) through a pipeline; the system also comprises a third check valve (18), a second gear (17), a first gear (16), a second clutch (15), a hydraulic motor (14), an auxiliary directional control valve (9), an accumulator (7), a hydraulic pump motor (12), a first switching valve (13), a second switching valve (19), a third switching valve (20), a second check valve (10), a fourth check valve (21), a first clutch (11), a flywheel (8) and a controller, the outlet B of the third check valve (18) is connected with the port S of the hydraulic pump (1) through a pipeline, and the inlet A of the third check valve (18) is connected with the oil tank (5) through a pipeline; the boom hydraulic cylinder (4) is a three-chamber hydraulic cylinder, the barrel of the boom hydraulic cylinder (4) is hinged with a turntable (200), and the rod end of the boom hydraulic cylinder (4) is hinged with the middle part of the boom (100); the second gear (17) is coaxially connected with the engine (6); the first gear (16) is meshed with the second gear (17), and the shaft of the first gear (16) is connected with the shaft of the hydraulic motor (14) through the second clutch (15); the port T of the hydraulic motor (14) is connected with the oil tank (5) through a pipeline, and the port P of the hydraulic motor (14) is connected with the port T of the second switching valve (19) through a pipeline; the port P of the second switching valve (19) is connected with the outlet B of the check valve (15), and the port A of the second switching valve (19) is connected with the port T of the auxiliary directional control valve (9); the port P of the auxiliary directional control valve (9) is simultaneously connected with the port P of the hydraulic pump motor (12) and the port P of the first switching valve (13) through pipelines, the port B of the auxiliary directional control valve (9) is connected with the accumulator (7) through a pipeline, and the port A of the auxiliary directional control valve (9) is blocked; the hydraulic pump motor (12) is connected with the shaft of the flywheel (8) through the first clutch (11), and the port S of the hydraulic pump motor (12) is connected with the oil tank (5) through a pipeline; the port A of the first switching valve (13) is synchronously connected with the port C of the boom hydraulic cylinder (4) and the outlet B of the second check valve (10) through pipelines, and the inlet A of the second check valve (10) is connected with the oil tank (5) through a pipeline; and the controller is respectively connected with the joystick, the engine (6), the main directional control valve (3), the auxiliary directional control valve (9), the first clutch (11), the second clutch (15), the first switching valve (13), the second switching valve (19), the third switching valve (20), the hydraulic pump motor (12) and the hydraulic motor (14).
2. The energy recovery and recycling integrated system according to claim 1, wherein the controller is a programmable logic controller (PLC).
3. The energy recovery and recycling integrated system according to claim 1 or 2, wherein the first switching valve (13) is a two-position two-way solenoid-actuated directional control valve, and works in the right position when de-energized and in the left position when energized; when the first switching valve (13) works in the right position, the oil passage between the port P and the port A is disconnected, and when the first switching valve (13) works in the left position, the oil passage between the port P and the port A is connected.
4. The energy recovery and recycling integrated system according to claim 3, wherein the second switching valve (19) is a two-position three-way solenoid-actuated directional control valve, and works in the left position when de-energized and in the right position when energized, when the second switching valve (19) works in the left position, the oil passage between the port P and the port A is disconnected, and the oil passage between the port T and the port A is connected; and when the second switching valve (19) works in the right position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port A is disconnected.
5. The energy recovery and recycling integrated system according to claim 4, wherein the main directional control valve (3) is a three-position four-way solenoid-actuated directional control valve, and works in the left position when an electromagnet Ylb of the main directional control valve (3) is energized, in the right position when an electromagnet Y a of the main directional control valve (3) is energized and in the center position when the two electromagnets Y1 a and Y 1 b of the main directional control valve (3) are de-energized; when the main directional control valve (3) works in the right position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port B is connected; when the main directional control valve (3) works in the left position, the oil passage between the port P and the port B is connected, and the oil passage between the port T and the port A is connected; and when the main directional control valve (3) works in the center position, the port P, the port A, the port T and the port B are not connected with one another.
6. The energy recovery and recycling integrated system according to claim 5, wherein the auxiliary directional control valve (9) is a three-position four-way solenoid-actuated directional control valve, and works in the left position when an electromagnet Y3b of the auxiliary directional control valve (9) is energized, in the right position when an electromagnet Y3a of the auxiliary directional control valve (9) is energized and in the center position when the two electromagnet Y3a and Y3b of the auxiliary directional control valve (9) are de-energized; when the auxiliary directional control valve (9) works in the right position, the oil passage between the port P and the port A is connected, and the oil passage between the port T and the port B is connected; when the auxiliary directional control valve (9) works in the left position, the oil passage between the port P and the port B is connected, and the oil passage between the port T and the port A is connected; and when the auxiliary directional control valve (9) works in the center position, the port P, the port A, the port T and the port B are not connected with one another.