CN204266284U - A kind of hydraulic excavating machine oil electricity liquid hybrid drive system - Google Patents

Abstract

The utility model discloses an oil-electro-hydraulic hybrid drive system for a hydraulic excavator, which comprises a hybrid drive system, a boom electro-hydraulic control unit, a turntable electro-hydraulic control unit, a hydraulic accumulator, a one-way valve, a pilot handle, a storage battery, a quantitative Pump/motor, second motor/generator, etc., the utility model uses battery and hydraulic accumulator as composite energy storage unit, uses hydraulic accumulator to provide or absorb instantaneous high power, and uses battery to ensure energy density. The turntable adopts the hybrid drive of electric/generator and hydraulic motor, and the hydraulic accumulator is used to ensure the instantaneous high power of the turntable when it starts and brakes, and the electric/generator ensures that the turntable has good speed control characteristics; through the hydraulic energy storage The active control of the actuator pressure adjusts the pressure control of the rodless cavity of the drive cylinder to realize the distribution of the gravitational potential energy of the boom on the balance cylinder as much as possible, thereby improving the energy recovery efficiency, and at the same time ensuring the speed control characteristics through the drive cylinder.

Description

An oil-electric-hydraulic hybrid drive system for a hydraulic excavator

technical field

The utility model belongs to the technical field of drive systems, in particular to an oil-electro-hydraulic hybrid drive system for a hydraulic excavator.

Background technique

As one of the most important construction machinery models for national infrastructure, hydraulic excavators have been widely used in construction, transportation, water conservancy, mining and military fields. The energy saving and emission reduction of hydraulic excavators has aroused people's widespread attention and attention. Therefore, hybrid power technology and energy recovery technology have always been the research focus of hydraulic excavators.

The working conditions of hydraulic excavators are complex, and the load changes drastically. Hybrid technology is one of the best solutions to improve the energy-saving effect of the power system. Hybrid power is generally divided into oil-electric hybrid technology using power storage units (battery or capacitor) as energy storage components and hydraulic hybrid technology using hydraulic accumulators as energy storage components. The energy density of the battery is high, but its power density is low, and the charging and discharging frequency is small, so it cannot provide high power to the system instantly. Supercapacitors have the characteristics of long life and large discharge current power, but currently the energy density of supercapacitors is low and the cost is high; in addition, hydraulic accumulators have the characteristics of low cost and long life, but the energy density of accumulators is very high. Low, accumulators store limited energy compared to batteries of the same size. Therefore, the current single oil-electric hybrid and hydraulic hybrid have their own strengths, and it is difficult to meet the requirements of high power density and high energy density at the same time.

At present, the conventional boom potential energy recovery scheme is mainly based on the oil-electric hybrid hydraulic excavator. The oil return chamber of the boom driving hydraulic cylinder is connected with the hydraulic motor, and the hydraulic motor is coaxially connected with the generator. The hydraulic oil that drives the oil return cavity of the oil cylinder drives the hydraulic motor to rotate, converts the hydraulic energy into mechanical energy output, and drives the generator to generate electricity. The three-phase AC power is rectified by the frequency converter into DC power and stored in the energy storage element. When the system needs it, the DC power is converted into a three-phase AC power of the target frequency through the rectifier to drive the motor, which drives the load together with the engine. In this technical solution, the potential energy recovery and reuse of all booms undergoes multiple energy conversions from potential energy-hydraulic energy-mechanical energy-electrical energy-capacitor-drive variable pump mechanical energy. There are many energy conversion links in the system, which affects the energy recovery of the system. efficiency. The boom potential energy recovery technology based on hydraulic hybrid deployment generally directly connects the rodless chamber of the drive cylinder with the hydraulic accumulator through a certain control valve block. When the boom is lowered, the pressure of the accumulator will gradually increase, making The speed of lowering the boom gradually slows down, which affects the driver's operating habits.

In the same way, the conventional energy recovery scheme for the rotary braking of the boarding mechanism is also mainly based on the development of hybrid electric power and hydraulic hybrid power. Since the battery cannot store high-power recyclable energy in an instant, the oil-electric hybrid system mainly uses electric motors instead of traditional hydraulic motors to drive the boarding mechanism, and uses the second and fourth quadrants of the electric motor to release a large amount of kinetic energy during slewing braking. It is converted into electric energy and stored in the capacitor, but the super capacitor is expensive and the technology is immature; based on the hydraulic hybrid technology, a secondary variable hydraulic pump/motor is generally used to drive the turntable, and the turntable is mainly recovered through the hydraulic accumulator when braking , because the hydraulic system itself is a strongly nonlinear system, it is difficult to precisely control the speed of the turntable, and there is a large impact at the moment of braking and starting of the turntable.

In view of this, the inventor of this case conducted in-depth research on the above-mentioned problem, and then this case was produced.

Utility model content

The purpose of this utility model is to provide an oil-electro-hydraulic hybrid drive system for a hydraulic excavator, which can not only improve the working efficiency of the engine, reduce the cost, but also recover the potential energy of the boom and the braking kinetic energy of the turntable without affecting the dynamics of the boom and turntable. operability.

In order to achieve the above object, the utility model adopts such technical scheme:

An oil-electro-hydraulic hybrid drive system for a hydraulic excavator, including a hybrid drive system, a boom electro-hydraulic control unit, a turntable electro-hydraulic control unit, a pilot handle, a one-way valve, a hydraulic accumulator, and a two-position two-way electromagnetic reversing valve , quantitative pump/motor, second electric motor/generator, storage battery, first motor controller, second motor controller, third motor controller;

The hybrid drive system includes an engine connected to a coaxial mechanical transmission, a first motor/generator, a pilot pump, a variable pump/motor and a variable pump;

The boom electro-hydraulic control unit includes a boom multi-way valve, a shuttle valve, a first hydraulically controlled two-position three-way reversing valve, a second hydraulically controlled two-position three-way reversing valve, a third hydraulically controlled two-position three-way One-way reversing valve, the fourth hydraulically controlled two-position three-way reversing valve, hydraulically controlled three-position four-way reversing valve, driving cylinder and balance cylinder;

The turntable electro-hydraulic control unit includes a three-position four-way electromagnetic reversing valve, a quantitative hydraulic motor, a third electric motor/generator, a reducer and a turntable;

The oil outlet of the pilot pump is connected with the oil inlet of the pilot handle, the boom control oil port bc1 of the pilot handle is connected with the control oil port K1 of the multi-way valve of the boom, the oil inlet of the shuttle valve, the third hydraulic control two-position three The control oil port K1 of the direct reversing valve and the control oil port K1 of the fourth hydraulically controlled two-position three-way reversing valve are connected; the boom control port bc2 of the pilot handle is respectively connected to the control oil port K2 of the boom multi-way valve , the other oil inlet of the shuttle valve and the control oil port K2 of the fourth hydraulically controlled two-position three-way reversing valve are connected;

The A port of the boom multi-way valve is divided into three routes: the first route is connected to the rodless chamber of the driving cylinder; the second route is connected to the control oil port K2 of the first hydraulically controlled two-position three-way reversing valve; The control oil port K1 of the hydraulically controlled two-position three-way reversing valve; the B port of the boom multi-way valve is divided into three routes: the first route is connected to the rod cavity of the driving cylinder; the second route is connected to the first hydraulic control two-position three-way port The control oil port K1 of the reversing valve; the third line is connected to the control oil port K2 of the second hydraulically controlled two-position three-way reversing valve; the D port of the boom multi-way valve is connected to the oil tank;

The oil outlet of the shuttle valve is divided into three routes: the first route is connected to the P port of the first hydraulically controlled two-position three-way reversing valve, and the A port of the first hydraulically controlled two-position three-way reversing valve is connected to the three-position four-way reversing valve The control oil port K2 of the valve, the T port of the first hydraulically controlled two-position three-way reversing valve is connected to the oil tank; the second road is connected to the P port of the second hydraulically controlled two-position three-way reversing valve, and the second hydraulically controlled The T port of the direct reversing valve is connected to the oil tank, the A port of the second hydraulic control two-position three-way reversing valve is connected to the T port of the fourth hydraulic control two-position three-way reversing valve; the third line is connected to the third hydraulic control two-position The P port of the three-way reversing valve, the T port of the third hydraulically controlled two-position three-way reversing valve is connected to the fuel tank, the A port of the third hydraulically controlled two-position three-way reversing valve is connected to the fourth hydraulically controlled two-position three-way reversing valve The P port of the directional valve, the A port of the fourth hydraulically controlled two-position three-way reversing valve is connected to the control oil port K1 of the hydraulically controlled three-position four-way reversing valve; the T port of the hydraulically controlled three-position four-way reversing valve is connected to the oil tank , the A port of the three-position four-way reversing valve is connected to the rodless chamber of the balance cylinder, the B port of the hydraulic control three-position four-way reversing valve is connected to the rod chamber of the balance cylinder, the piston rod of the driving cylinder, and the piston rod of the balance cylinder Rigidly connected to the boom;

Port A of the three-position four-way electromagnetic reversing valve is connected to the hydraulic accumulator, port B of the three-position four-way electromagnetic reversing valve is connected to the fuel tank, and ports P and T of the three-position four-way electromagnetic reversing valve are respectively connected to the quantitative The two chambers of the hydraulic motor are connected, and the quantitative hydraulic motor, the third electric motor/generator, the reducer and the turntable are mechanically connected;

The outlet of the variable hydraulic pump/motor is connected to the oil inlet of the one-way valve, and the oil outlet of the one-way valve is connected to the P port and the P1 port of the boom multi-way valve; the first electric motor/generator is connected to the first motor controller electric The second motor/generator is electrically connected to the second motor controller, the third motor/generator is electrically connected to the third motor controller, the first motor controller, the second motor controller, the third motor The controller is electrically connected to the battery;

Port B of the two-position two-way electromagnetic reversing valve (21) is connected to the quantitative pump/motor (22), the quantitative pump/motor (22) is connected to the second electric motor/generator (23), and the two-position two-way electromagnetic reversing The A port of the valve (21) is connected with the hydraulic accumulator (18), the P port of the hydraulically controlled three-position four-way reversing valve (14), the pressure sensor (19), the safety valve (20) and the three-position four-way electromagnetic commutator. Connect to port A of valve (27).

In the above solution, other hydraulic systems are also included, and other hydraulic systems include arm drive system, bucket drive system and travel drive system, and the outlet of the variable hydraulic pump is connected with other hydraulic systems.

Preferably, the first motor/generator, the second motor/generator and the third motor/generator are equipped with sensors for measuring rotational speed, and the sensors are rotary transformers or photoelectric encoders.

Compared with the prior art, the utility model has the following beneficial effects:

1. The utility model adopts the storage battery and the hydraulic accumulator at the same time. The storage battery has the advantage of high energy density, and is mainly responsible for balancing the relatively gentle fluctuation of the working condition, and can also provide electric energy for the drive motor of the turntable to realize the speed control of the turntable. The accumulator can provide or absorb instantaneous high power, realize the recovery of the potential energy of the boom and the braking kinetic energy of the turntable, and realize the function of a super capacitor, but the cost is lower than that of a super capacitor;

2. In terms of potential energy recovery of the boom, the utility model ensures the speed control characteristics of the boom by driving the oil cylinder, and recovers the potential energy of the boom through the balance oil cylinder and hydraulic accumulator, which follows the minimum principle of energy conversion and avoids energy The energy loss caused by multiple transformations, and at the same time adjust the pressure of the rodless cavity of the drive cylinder through active control of the pressure of the hydraulic accumulator, so that the potential energy of the boom is distributed to the balance cylinder as much as possible, and the recovery efficiency of the potential energy of the boom is improved;

3. In terms of turntable drive, the electric/generator and hydraulic motor compound drive method is adopted, the high power of the turntable at the moment of starting and braking is guaranteed through the hydraulic accumulator, and the speed control characteristics of the turntable are guaranteed through the third electric/generator.

4. In terms of energy reuse, the utility model also follows the principle of the minimum energy conversion link. The energy of the hydraulic accumulator can not only directly drive the boom through the balance oil cylinder, but also release it to the quantitative hydraulic motor to drive the turntable with two chambers. When the energy of the hydraulic accumulator is high, the quantitative pump/motor and the second motor/generator can convert the energy into electrical energy and store it in the storage battery for use by the first motor/generator to assist the engine to drive the pilot pump.

Description of drawings

Fig. 1 is the overall structural block diagram of the preferred embodiment of the utility model;

Fig. 2 is a control block diagram of the second motor/generator in the utility model.

In the picture:

1. Engine 2. The first motor/generator

3. Pilot pump 4. Variable displacement pump/motor

5. Variable pump 6. Pilot handle

7. Boom multi-way valve 8. One-way valve

9. Shuttle valve 10. The first hydraulically controlled two-position three-way reversing valve

11. The second hydraulically controlled two-position three-way reversing valve 12. The third hydraulically controlled two-position three-way reversing valve

13. The fourth hydraulically controlled two-position three-way reversing valve 14. Hydraulically controlled three-position four-way reversing valve

15. Drive cylinder 16. Balance cylinder

17. Boom 18. Hydraulic accumulator

19. Pressure sensor 20. Safety valve

21. Two-position two-way electromagnetic reversing valve 22. Quantitative pump/motor

23. Second motor/generator 24. Second motor controller

25. Battery 26. First motor controller

27. Three-position four-way electromagnetic reversing valve 28. Quantitative hydraulic motor

29. The third motor controller 30. The third motor/generator

31. Reducer 32. Turntable

33. Other hydraulic systems 100. Hybrid drive system

200. Boom electro-hydraulic control unit 300. Turntable electro-hydraulic control unit

Detailed ways

In order to further explain the technical solution of the present utility model, it will be described in detail below in conjunction with the accompanying drawings.

1 to 2, an oil-electro-hydraulic hybrid drive system for a hydraulic excavator includes a hybrid drive system 100, a boom electro-hydraulic control unit 200, a turntable electro-hydraulic control unit 300, a pilot handle 6, a one-way valve 8, a hydraulic Accumulator 18, two-position two-way electromagnetic reversing valve 21, quantitative pump/motor 22, second motor/generator 23, storage battery 25, first motor controller 26, second motor controller 24, third motor controller device 29;

The hybrid drive system 100 includes an engine 1, a first electric motor/generator 2, a pilot pump 3, a variable displacement pump/motor 4, and a variable displacement pump 5 connected by coaxial mechanical transmission;

The boom electro-hydraulic control unit 200 includes a boom multi-way valve 7, a shuttle valve 9, a first hydraulically controlled two-position three-way reversing valve 10, a second hydraulically controlled two-position three-way reversing valve 11, and a third hydraulically controlled two-position three-way reversing valve 11. Hydraulically controlled two-position three-way reversing valve 12, fourth hydraulically controlled two-position three-way reversing valve 13, hydraulically controlled three-position four-way reversing valve 14, driving cylinder 15 and balance cylinder 16;

The turntable electro-hydraulic control unit 300 includes a three-position four-way electromagnetic reversing valve 27, a quantitative hydraulic motor 28, a third electric/generator 30, a reducer 31 and a turntable 32;

The oil outlet of the pilot pump 3 is connected with the oil inlet of the pilot handle 6, the boom control oil port bc1 of the pilot handle 6 is connected with the control oil port K1 of the boom multi-way valve 7, the oil inlet of the shuttle valve 9, the third The control port K1 of the hydraulically controlled two-position three-way reversing valve 12 and the control oil port K1 of the fourth hydraulically controlled two-position three-way reversing valve 13 are connected; the boom control port bc2 of the pilot handle 6 is respectively connected to the The control oil port K2 of the multi-way valve 7, the other oil inlet port of the shuttle valve 9, and the control oil port K2 of the fourth hydraulically controlled two-position three-way reversing valve 13 are all connected;

The A port of the boom multi-way valve 7 is divided into three routes: the first route is connected to the rodless cavity of the drive cylinder 15; the second route is connected to the control port K2 of the first hydraulically controlled two-position three-way reversing valve 10; the third route Connect to the control oil port K1 of the second hydraulically controlled two-position three-way reversing valve 11; the B port of the boom multi-way valve 7 is divided into three routes: the first route is connected to the rod chamber of the drive cylinder 15; the second route is connected to the first The control oil port K1 of the hydraulically controlled two-position three-way reversing valve 10; the third line is connected to the control oil port K2 of the second hydraulic control two-position three-way reversing valve 11; the D port of the boom multi-way valve 7 is connected to the oil tank ;

The oil outlet of the shuttle valve 9 is divided into three routes: the first route is connected to the P port of the first hydraulically controlled two-position three-way reversing valve 10, and the A port of the first hydraulically controlled two-position three-way reversing valve 10 is connected to the three-position four-way The control oil port K2 of the reversing valve 14, the T port of the first hydraulically controlled two-position three-way reversing valve 10 is connected to the oil tank; the second road is connected to the P port of the second hydraulically controlled two-position three-way reversing valve 11, the second The T port of the second hydraulically controlled two-position three-way reversing valve 11 is connected to the oil tank, and the A port of the second hydraulically controlled two-position three-way reversing valve 11 is connected to the T port of the fourth hydraulically controlled two-position three-way reversing valve 13; The three-way is connected to the P port of the third hydraulically controlled two-position three-way reversing valve 12, the T port of the third hydraulically controlled two-position three-way reversing valve 12 is connected to the oil tank, and the third hydraulically controlled two-position three-way reversing valve 12 is connected to the P port. Port A is connected to port P of the fourth hydraulically controlled two-position three-way reversing valve 13, and port A of the fourth hydraulically controlled two-position three-way reversing valve 13 is connected to control oil port K1 of the hydraulically controlled three-position four-way reversing valve 14 ; The T port of the hydraulic control three-position four-way reversing valve 14 is connected to the oil tank, the A port of the three-position four-way reversing valve 14 is connected to the rodless chamber of the balance oil cylinder 16, and the port of the hydraulic control three-position four-way reversing valve (14) Port B is connected to the rod cavity of the balance oil cylinder (16), the piston rod of the drive oil cylinder (15), the piston rod of the balance oil cylinder 16 are rigidly connected with the boom 17;

The A port of the three-position four-way electromagnetic reversing valve 27 is connected to the hydraulic accumulator 18, the B port of the three-position four-way electromagnetic reversing valve 27 is connected to the fuel tank, and the P port of the three-position four-way electromagnetic reversing valve 27 is connected to the T The ports are respectively connected to the two chambers of the quantitative hydraulic motor 28, and the quantitative hydraulic motor 28, the third electric motor/generator 30, the reducer 31 and the turntable 32 are mechanically connected;

The outlet of the variable hydraulic pump/motor 4 is connected to the oil inlet of the one-way valve 8, and the oil outlet of the one-way valve 8 is connected to the P port and the P1 port of the boom multi-way valve 7; the first motor/generator 2 is connected to the second A motor controller 26 is electrically connected, the second motor/generator 23 is electrically connected to the second motor controller 24, the third motor/generator 30 is electrically connected to the third motor controller 29, and the first motor controller 26. The second motor controller 24, the third motor controller 29 are electrically connected to the storage battery 25;

The port B of the two-position two-way electromagnetic reversing valve 21 is connected to the quantitative pump/motor 22, the quantitative pump/motor 22 is connected to the second electric motor/generator 23, and the A port of the two-position two-way electromagnetic reversing valve 21 is connected to the hydraulic accumulator Energizer 18, P port of hydraulic control three-position four-way reversing valve 14, pressure sensor 19, safety valve 20 and A port of three-position four-way electromagnetic reversing valve 27 are connected. The pressure sensor 19 is used to measure the pressure of the hydraulic accumulator 18 and transmit the signal.

The utility model also includes other hydraulic systems 33 , and the other hydraulic systems 33 include a stick drive system, a bucket drive system and a walking drive system, and the outlet of the variable hydraulic pump 5 is connected with the other hydraulic systems 33 .

The first motor/generator 2 , the second motor/generator 23 and the third motor/generator 30 are all equipped with sensors for measuring rotational speed, and the sensors are rotary transformers or photoelectric encoders.

The pilot handle 6 of the present utility model is a conventional product of construction machinery at present. The pilot handle 6 in Fig. 1 only controls the boom and the turntable, and actually can also control other actuators, such as sticks and buckets.

Concrete working principle of the present utility model is as follows:

The controller (not shown in the figure) of the excavator obtains the pilot control pressure by collecting and data processing the pressure signal output by the pilot handle 6, and judges whether the working mode of the boom 17 is rising or lowering and the working mode of the turntable 32. Whether the mode is turning left or turning right, the controller of the excavator accepts the outlet pressure signal of the detected variable pump/motor 4 and variable pump 5, the current signal of the pressure sensor 19, the management controller of the storage battery 25 (not shown in the figure) ) output signal representing the remaining power SOC of the storage battery 25 and the output voltage signal representing the displacement of the variable pump/motor 4 and the amplifier board (not shown in the figure) of the variable pump 5, to the engine 1, the first motor controller 26 , the second motor controller 24, the third motor controller 29, the two-position two-way electromagnetic reversing valve 21 and the three-position four-way electromagnetic reversing valve 27 etc. send control commands, thereby controlling the throttle of the engine 1, the two-position two-way The station of the electromagnetic reversing valve 21, the displacement of the spool of the three-position four-way electromagnetic reversing valve 27, the first motor controller 26, the second motor controller 24 and the third motor controller 29 are controlled by the excavator. The first motor controller 26, the second motor controller 24, and the third motor controller 29 send signals to the first motor/generator 2, the second motor/generator 23, and the third motor/generator respectively. 30 issues control commands to control the working modes and target control signals of the first motor/generator 2 , the second motor/generator 23 and the third motor/generator 30 .

Concrete control process of the present utility model is as follows:

(1) Control rules of the first motor/generator

The determination thresholds S ₁ and S ₂ of the SOC (remaining power) of the storage battery 25 are set so that S ₁ < S ₂ is satisfied. The judgment thresholds p ₁₁ and p ₁₂ of the pressure p ₁ of the hydraulic accumulator 18 are set, and p ₁₁ <p ₁₂ is satisfied. The power system workflow is as follows:

(1) The driver sets the initial throttle position of the engine 1 .

(2) According to the universal characteristic curve of the engine 1, the speed n _Et and the torque T _Et corresponding to the minimum fuel consumption rate of the engine corresponding to the throttle gear are obtained, and the engine 1 is started and started to work.

(3) Calculate the torque T _L required by the load by detecting the outlet pressure and displacement of the variable pump/motor 4 and the variable pump 5 .

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; L</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, p _p1 ——the outlet pressure of the variable pump/motor 4; the unit is MPa

p _p2 ——Outlet pressure of variable pump 5; unit MPa

q _p1 ——displacement of variable pump/motor 4; unit ml/r

q _p2 ——displacement of variable pump 5; unit ml/r

(4) The target torque of the first motor/generator 2 is:

T _EMt =T _L -T _Et (2)

In the formula, when T _EMt is greater than zero, the first motor/generator 2 works in the electric mode to assist the engine 1 to drive the pilot pump 3; when T _EMt is less than zero, the first motor/generator 2 works in the power generation mode , convert the excess energy of the engine 1 relative to the load into electrical energy and store it in the storage battery 25 .

(2) Working principle of the second motor/generator 23

The quantitative pump/motor 22 and the second electric motor/generator 23 serve as energy conversion units between the hydraulic accumulator 18 and the storage battery 25 . The working principle of the second motor/generator 23 satisfies the boom lowering mode priority and energy balance mode, specifically:

1. Optimization of boom lowering mode

Assume that the pressure of the rodless chamber of the drive cylinder 15 is pb1, the pressure of the rodless chamber of the balance cylinder is pb2, and assume that the output pressures corresponding to the pilot handle 6 boom control oil port bc1 and boom control oil port bc2 are respectively bc1 and bc2, when bc1 and bc2 represent that when the boom 17 is lowered, the gravitational potential energy of the boom 17 is converted into hydraulic energy and stored in the rodless cavity of the drive cylinder 15 and the rodless cavity of the balance cylinder 16, wherein the hydraulic pressure of the rodless cavity of the drive cylinder 15 The energy can be finally consumed on the valve port of the boom multi-way valve 7, and cannot be recovered; the hydraulic energy of the rodless chamber of the balance cylinder 16 can be recovered through the hydraulic accumulator 18, and in addition, during the recovery process, the hydraulic energy of the hydraulic accumulator 18 As the pressure increases gradually, the pressure in the rodless cavity of the driving cylinder 15 decreases gradually. Therefore, when the boom 17 is lowered, the distribution ratio of its gravitational potential energy between the driving cylinder 15 and the balance cylinder 16 changes gradually. In order to improve the recovery efficiency of the gravitational potential energy of the boom 17, a control rule based on the active control of the pressure of the hydraulic accumulator 18 is proposed, through the active control of the pressure of the hydraulic accumulator 18 by the quantitative pump/motor 22, the boom is actively adjusted The gravitational potential energy of 17 is distributed in the rodless cavity of balance oil cylinder 16 as much as possible. When the target pressure of the rodless chamber of the driving cylinder is zero, the gravitational potential energy of the boom 17 can be distributed in the rodless chamber of the balance cylinder 16 as much as possible. The difference between the target pressure of the rodless chamber of the driving cylinder and the detection pressure of the pressure sensor installed in the rodless chamber of the driving cylinder is used as the input signal of the PI controller, and the output signal is generated by the PI controller, and then the output signal is limited, The speed of the second motor/generator 23 is controlled by the second motor controller 24, thereby actively adjusting the pressure of the hydraulic accumulator 18. Under the action of the same boom 17, the pressure of the rodless chamber of the drive cylinder 15 is also changed. .

2. Energy balance mode:

When the boom 17 is not in the lowering mode, the second motor/generator 23 works in the energy balance mode, specifically as follows:

1) When the SOC of the battery 25 satisfies SOC>S ₂ , the power of the battery 25 is relatively sufficient at this time, and if the pressure of the hydraulic accumulator 18 does not exceed its maximum pressure p ₁₂ , the two-position two-way electromagnetic reversing valve 21 Get electricity, quantitative pump/motor 22 and second motor/generator 23 work, now second motor/generator 23 works in electric mode, quantitative pump/motor 22 works in pump mode, and hydraulic accumulator 18 is filled with oil , convert the electric energy of the battery 25 into hydraulic energy and store it in the hydraulic accumulator 18; if the pressure of the hydraulic accumulator 18 exceeds its maximum pressure p ₁₂ , the two-position two-way electromagnetic reversing valve 21 loses power, and the second electric/ Generator 23 does not work;

2) When the SOC of the battery 25 satisfies SOC<S ₁ , the power of the battery 25 is insufficient at this time, and if the pressure of the hydraulic accumulator 18 is not lower than its minimum working pressure p ₁₁ , the two-position two-way electromagnetic reversing valve 21 Get electricity, quantitative pump/motor 22 and second motor/generator 23 work, and now second motor/generator 23 works in generator mode, quantitative pump/motor 22 works in motor mode, and hydraulic accumulator 18 The hydraulic energy is converted into electric energy and stored in the accumulator 25; if the pressure of the hydraulic accumulator 18 is lower than its minimum working pressure _p11 , the two-position two-way electromagnetic reversing valve 21 loses power, and the second motor/generator 23 does not work ;

3) When the SOC of the battery 25 satisfies S ₁ ≤ SOC ≤ S ₂ , the power of the battery 25 is in a reasonable fluctuation range, the two-position two-way electromagnetic reversing valve 21 loses power, and the second motor/generator 23 does not work.

(3) Boom electro-hydraulic control system

(1) The drive cylinder 15 and balance cylinder 16 are retracted

When the output pressure bc2 of the pilot handle 6 is greater than zero and bc1 is approximately zero, it means that the driving cylinder 15 and the balance cylinder 16 are retracted, and the control oil port K1 of the boom multi-way valve 7 is connected to the output pressure bc1 of the pilot handle. The control oil port K2 of the boom multi-way valve 7 is connected to the output pressure bc2 of the pilot handle, so the boom multi-way valve 7 works in the right position, and the rodless cavity of the driving cylinder 15 is connected to the oil port A-T of the boom multi-way valve 7 The oil tank, the drive cylinder 15 has a rod chamber connected to the hydraulic oil from the variable pump/motor 4 through the oil port P-B of the multi-way valve 7 of the boom; the multi-way valve 7 of the boom is controlled by controlling the output pressure bc1 and bc2 of the pilot handle 6 The displacement of the spool realizes the control of the lowering speed or digging force of the boom 17. The boom mode is divided into two modes: the boom lowering mode and the boom digging mode.

1) Boom down mode

When the bucket (not shown) of the excavator does not touch the excavation object, the boom 17 is in the actual lowering process. At this time, the pressure in the rodless chamber of the drive cylinder 15 is greater than the pressure in the rod chamber, and the first hydraulically controlled two-position three-way switch The directional valve 10 works at the right position, and the control oil port K2 of the hydraulically controlled three-position four-way reversing valve 14 is connected to the fuel tank through the first hydraulically controlled two-position three-way reversing valve 10; the second hydraulically controlled two-position three-way reversing valve Valve 11 works at the left station, the third hydraulically controlled two-position three-way reversing valve 12 and the fourth hydraulically controlled two-position three-way reversing valve 13 both work at the right station, and the output pressure signals bc1 and bc2 of the pilot handle pass through The oil outlet of the shuttle valve 9, the second hydraulically controlled two-position three-way reversing valve 11, the fourth hydraulically controlled two-position three-way reversing valve 13 and the control oil port K1 of the hydraulically controlled three-position four-way reversing valve 14, Therefore, the hydraulically controlled three-position four-way reversing valve 14 works at the left station, the rodless chamber of the balance cylinder 16 is connected to the hydraulic accumulator 18, and the rod chamber of the balance cylinder 16 is connected to the hydraulically controlled three-position four-way reversing valve. 14 is connected to the oil tank, at this time the pressure of the hydraulic accumulator 18 is the pressure of the rodless chamber of the balance oil cylinder 16, and the pressure of the hydraulic accumulator 18 gradually increases during the lowering of the boom 17 to realize the gravity of the boom 17. Potential energy recovery;

2) Boom digging mode

The bucket touches the excavation object, and the boom 17 does not actually lower down. The functions of the driving cylinder 15 and the balance cylinder 16 are to ensure that the bucket provides a digging force when digging, and ensure that the entire mechanical arm will not be bounced back when the bucket is digging . At this time, the pressure in the rodless cavity of the drive cylinder 15 is lower than the pressure in the rod cavity, the first hydraulically controlled two-position three-way reversing valve 10 works in the left position, and the control oil port K2 of the hydraulically controlled three-position four-way reversing valve 14 passes through The oil inlets of the first hydraulically controlled two-position three-way reversing valve 10 and the shuttle valve 9 are connected to the pilot handle 6; the second hydraulically controlled two-position three-way reversing valve 11 works at the right station, and the third hydraulically controlled two-position The three-way reversing valve 12 and the fourth hydraulically controlled two-position three-way reversing valve 13 both work in the right position, and the control oil port K1 of the hydraulically controlled three-position four-way reversing valve 14 passes through the second hydraulically controlled two-position three-way The reversing valve 11 and the fourth hydraulically controlled two-position three-way reversing valve 13 are connected to the fuel tank, so the hydraulically controlled three-position four-way reversing valve 14 works in the right position, and the rod chamber and hydraulic accumulator of the balance oil cylinder 16 18, and the rodless chamber of the balance cylinder 16 is connected to the oil tank through the hydraulically controlled three-position four-way reversing valve 14. At this time, the pressure of the hydraulic accumulator 18 is the pressure of the rod chamber of the balance cylinder 16, and the boom 17 is During the excavation process, the hydraulic accumulator 18 assists the driving cylinder 15 to provide a larger digging force, thereby reducing the pressure of the rod chamber of the driving cylinder 15, thereby reducing the output pressure of the variable pump/motor 4, and reducing energy loss; Simultaneously because when excavating, the displacement of boom 17 is small, therefore, the pressure drop of hydraulic accumulator 18 is small.

(2) Drive cylinder 15 and balance cylinder 16 stretch out

When the output pressure bc1 of the pilot handle 6 is greater than zero and bc2 is approximately zero, it means that the driving cylinder 15 and the balance cylinder 16 are stretched out. At this time, the control oil port K1 of the boom multi-way valve 7 is connected to the output pressure bc1 of the pilot handle. The control oil port K2 of the boom multi-way valve 7 is connected to the output pressure bc2 of the pilot handle, so the boom multi-way valve 7 works in the left position, and the rod chamber of the driving cylinder 15 is connected to the oil port A-T of the boom multi-way valve 7 The oil tank, the rodless cavity of the drive cylinder 15 is connected to the hydraulic oil from the variable pump/motor 4 through the oil port P-B of the multi-way valve 7 of the boom; the multi-way valve 7 of the boom is controlled by controlling the output pressure bc1 and bc2 of the pilot handle 6 The displacement of the spool realizes controlling the rising speed of the boom 17.

At this time, the pressure in the rodless chamber of the driving cylinder 15 is greater than the pressure in the rod chamber, the first hydraulically controlled two-position three-way reversing valve 10 works in the right position, and the control oil port K2 of the hydraulically controlled three-position four-way reversing valve 14 passes through The first hydraulically controlled two-position three-way reversing valve 10 is connected to the oil tank; the second hydraulically controlled two-position three-way reversing valve 11 works at the left station, the third hydraulically controlled two-position three-way reversing valve 12 and the fourth hydraulically controlled two-position three-way reversing valve 12 The two-position three-way reversing valve 13 all work in the left position, and the control oil port K1 of the hydraulically controlled three-position four-way reversing valve 14 passes through the third hydraulically controlled two-position three-way reversing valve 12 and the fourth hydraulically controlled two-position The three-way reversing valve 13 is connected to the oil outlet of the shuttle valve 9, the output pressure signals bc1 and bc2 of the pilot handle pass through the oil outlet of the shuttle valve 9, the third hydraulically controlled two-position three-way reversing valve 12, the fourth hydraulic The control oil port K1 of the two-position three-way reversing valve 13 and the hydraulic control three-position four-way reversing valve 14, so the hydraulic control three-position four-way reversing valve 14 works in the left position, and the rodless cavity of the balance cylinder 16 It is connected with the hydraulic accumulator 18, and the rod chamber of the balance cylinder 16 is connected with the oil tank through the hydraulically controlled three-position four-way reversing valve 14. At this time, the pressure of the hydraulic accumulator 18 is the pressure of the rodless chamber of the balance cylinder 16. , when the boom 17 is rising, the hydraulic accumulator 18 assists the drive cylinder 15 to drive the boom 17 to rise, thus reducing the rodless chamber pressure of the drive cylinder 15, thereby reducing the output pressure of the variable pump/motor 4, and reducing the Energy loss, at this time the pressure of the hydraulic accumulator 18 gradually drops.

(3) Drive cylinder 15 and balance cylinder 16 stop

When the pilot handle 6 returns to the neutral position, the output pressures bc1 and bc2 of the pilot handle are both approximately zero. At this time, the boom multi-way valve 7 is in the neutral position. The hydraulic control two-position three-way reversing valve 11, the third hydraulic control two-position three-way reversing valve 12 and the fourth hydraulic control two-position three-way reversing valve 13 all work in the right position, and the hydraulic control three-position four-way reversing The control oil ports K1 and K2 at both ends of the valve 14 are both connected to the oil tank, and the hydraulically controlled three-position four-way reversing valve 14 works in the neutral position, so the rodless and rod chambers of the drive cylinder 15 and balance cylinder 16 are disconnected.

(4) The principle of turntable control process

The sc1 and sc2 of the pilot handle 6 in Fig. 1 are pilot handle signals, which are used to represent the target rotational speed signal of the turntable.

(1) When the turntable 32 rotates left and brakes

The pilot handle 6 returns to the neutral position, sc1 and sc2 are both approximately zero; the turntable 32 continues to rotate to the left under the action of inertia, and high pressure is generated in the cavity A of the hydraulic motor 28. At this time, the three-position four-way electromagnetic reversing valve 27 The left electromagnet is energized, the right electromagnet is de-energized, the three-position four-way electromagnetic reversing valve 27 works at the left position, and the hydraulic accumulator 18 passes through the P-A of the three-position four-way electromagnetic reversing valve 27, the hydraulic motor 28 and the three-position The oil port B-T of the four-way electromagnetic reversing valve 27 is connected to the oil tank, and a reverse braking torque is generated in the two chambers of the hydraulic motor 28 to realize the braking process of the turntable 32. At the same time, the hydraulic accumulator 18 realizes the braking of the turntable 32 Energy recovery of kinetic energy; since the flow rate of the hydraulic accumulator 18 is difficult to accurately control, the rotating speed of the turntable 32 is controlled by the third motor/generator 30, and the working torque of the third motor/generator 30 is caused by the braking of the turntable 32 The difference between the required torque and the braking torque provided by the hydraulic motor 28. When the speed signal n measured by the speed sensor of the third motor/generator 30 is approximately zero, the left and right electromagnets of the three-position four-way electromagnetic reversing valve 27 are de-energized, and the mechanical braking system (not shown) works .

(2) When the turntable 32 rotates to the right and brakes

The pilot handle 6 returns to the neutral position, and both sc1 and sc2 are approximately zero; the turntable 32 continues to rotate to the right under the action of inertia, and high pressure is generated in the B chamber of the hydraulic motor 28. At this time, the right side of the three-position four-way electromagnetic reversing valve 27 The electromagnet is energized, the left electromagnet is de-energized, the three-position four-way electromagnetic reversing valve 27 works at the right position, and the hydraulic accumulator 18 passes through the A-T of the three-position four-way electromagnetic reversing valve 27, the hydraulic motor 28 and the three-position four-way valve. The oil port P-B of the electromagnetic reversing valve 27 is connected to the oil tank, and a reverse braking torque is generated in the two chambers of the hydraulic motor 28 to realize the braking process of the turntable 32. At the same time, the braking kinetic energy of the turntable 32 is realized through the hydraulic accumulator 18 energy recovery; since the flow rate of the hydraulic accumulator 18 is difficult to accurately control, the rotating speed of the turntable 32 is realized by controlling the third motor/generator 30, and the operating torque of the third motor/generator 30 is required for the braking of the turntable 32 The difference between the torque and the braking torque provided by the hydraulic motor 28. When the speed signal n measured by the speed sensor of the third motor/generator 30 is approximately zero, the left and right electromagnets of the three-position four-way electromagnetic reversing valve 27 are de-energized, and the mechanical braking system (not shown) works .

(3) When the turntable 32 starts to accelerate or rotate at a constant speed

When the speed signal n measured by the speed sensor of the third motor/generator 30 is close to the target speed of the turntable represented by sc1 and sc2, it means that the turntable 32 has been started. Both left and right electromagnets of the reversing valve 27 are de-energized, and the speed of the turntable 32 is mainly adjusted by the third motor/generator 30 .

(4) Turntable 32 is on the left side wall for excavation

When the rotational speed signal n measured by the rotational speed sensor of the third motor/generator 30 is close to zero, but the target rotational speed signal of the turntable represented by sc1 and sc2 (sc1 is larger, sc2 is approximately zero) is larger, it means that the turntable 32 is in a left position. In the sidewall excavation mode, the rotational speed of the turntable 32 is zero at this time, but the turntable 32 needs to provide a larger left-hand rotation torque. At this time, the right electromagnet of the three-position four-way electromagnetic reversing valve 27 is energized, and the left electromagnet is de-energized. The A-T of the directional valve 27, the hydraulic motor 28, and the oil port P-B of the three-position four-way electromagnetic reversing valve 27 are connected to the oil tank, and a left-handed driving torque is generated in the two chambers of the hydraulic motor 28, and the insufficient driving torque is provided by the third motor/generator. 30, the output torque of the third motor/generator 30 is reduced, thereby realizing energy saving.

(5) Turntable 32 is on the right side wall for excavation

When the rotational speed signal n measured by the rotational speed sensor of the third motor/generator 30 is close to zero, but the target rotational speed signal of the turntable represented by sc1 and sc2 (sc2 is larger, and sc1 is approximately zero) is larger, it means that the turntable 32 is in a right position. In the sidewall excavation mode, the rotational speed of the turntable 32 is zero at this time, but the turntable 32 needs to provide a larger right-hand rotation torque. At this time, the left electromagnet of the three-position four-way electromagnetic reversing valve 27 is energized, and the right electromagnet is de-energized. The P-A of the directional valve 27, the hydraulic motor 28, and the oil port B-T of the three-position four-way electromagnetic reversing valve 27 are connected to the oil tank, and a right-rotation driving torque is generated in the two chambers of the hydraulic motor 28, and the insufficient driving torque is provided by the third electric/generator motor 30, which reduces the output torque of the third motor/generator 30, thereby realizing energy saving.

The product form of the present utility model is not limited to the illustrations and examples of this case, and anyone who makes appropriate changes or modifications of similar ideas to it should be considered as not departing from the patent category of the present utility model.

Claims (3)

1. An oil-electro-hydraulic hybrid drive system for a hydraulic excavator, characterized in that it includes a hybrid drive system (100), a boom electro-hydraulic control unit (200), a turntable electro-hydraulic control unit (300), and a pilot handle (6) , one-way valve (8), hydraulic accumulator (18), two-position two-way electromagnetic reversing valve (21), quantitative pump/motor (22), second electric motor/generator (23), battery (25) , the first motor controller (26), the second motor controller (24), the third motor controller (29); The hybrid drive system (100) includes an engine (1), a first electric motor/generator (2), a pilot pump (3), a variable displacement pump/motor (4) and a variable displacement pump (5) connected by a coaxial mechanical transmission ; The boom electro-hydraulic control unit (200) includes a boom multi-way valve (7), a shuttle valve (9), a first hydraulically controlled two-position three-way reversing valve (10), a second hydraulically controlled two-position three-way One-way reversing valve (11), third hydraulically controlled two-position three-way reversing valve (12), fourth hydraulically controlled two-position three-way reversing valve (13), hydraulically controlled three-position four-way reversing valve (14) , drive oil cylinder (15) and balance oil cylinder (16); The turntable electro-hydraulic control unit (300) includes a three-position four-way electromagnetic reversing valve (27), a quantitative hydraulic motor (28), a third electric motor/generator (30), a reducer (31) and a turntable (32 ); The oil outlet of the pilot pump (3) is connected to the oil inlet of the pilot handle (6), the boom control oil port bc1 of the pilot handle (6) is connected to the control oil port K1 of the boom multi-way valve (7), and the shuttle valve The oil inlet of (9), the control oil port K1 of the third hydraulically controlled two-position three-way reversing valve (12) and the control oil port K1 of the fourth hydraulically controlled two-position three-way reversing valve (13) are all connected; The boom control oil port bc2 of the pilot handle (6) is respectively reversible with the control oil port K2 of the boom multi-way valve (7), the other oil inlet of the shuttle valve (9) and the fourth hydraulic control two-position three-way The control oil ports K2 of the valve (13) are all connected; The A port of the boom multi-way valve (7) is divided into three routes: the first route is connected to the rodless cavity of the driving cylinder (15); the second route is connected to the control oil of the first hydraulically controlled two-position three-way reversing valve (10) Port K2; the third road is connected to the control oil port K1 of the second hydraulically controlled two-position three-way reversing valve (11); the B port of the boom multi-way valve (7) is divided into three roads: the first road is connected to the driving cylinder (15 ) rod chamber; the second road is connected to the control oil port K1 of the first hydraulically controlled two-position three-way reversing valve (10); the third road is connected to the control port of the second hydraulically controlled two-position three-way reversing valve (11) Oil port K2; the D port of the boom multi-way valve (7) is connected with the oil tank; The oil outlet of the shuttle valve (9) is divided into three routes: the first route is connected to the P port of the first hydraulically controlled two-position three-way reversing valve (10), and the port P of the first hydraulically controlled two-position three-way reversing valve (10) Port A is connected to the control oil port K2 of the three-position four-way reversing valve (14), the T port of the first hydraulically controlled two-position three-way reversing valve (10) is connected to the oil tank; the second road is connected to the second hydraulically controlled two-position three-way Port P of the reversing valve (11), T port of the second hydraulically controlled two-position three-way reversing valve (11) is connected to the fuel tank, port A of the second hydraulically controlled two-position three-way reversing valve (11) is connected to the first The T port of the four hydraulically controlled two-position three-way reversing valve (13); the third line is connected to the P port of the third hydraulically controlled two-position three-way reversing valve (12), and the third hydraulically controlled two-position three-way reversing valve The T port of (12) is connected to the oil tank, the A port of the third hydraulically controlled two-position three-way reversing valve (12) is connected to the P port of the fourth hydraulically controlled two-position three-way reversing valve (13), and the fourth hydraulically controlled two-position three-way reversing valve The A port of the 3-position 4-way reversing valve (13) is connected to the control oil port K1 of the hydraulically controlled 3-position 4-way reversing valve (14); the T port of the hydraulically controlled 3-position 4-way reversing valve (14) is connected to the oil tank. A port of the four-position directional control valve (14) is connected to the rodless chamber of the balance oil cylinder (16), and port B of the hydraulically controlled three-position four-way reversing valve (14) is connected to the rod chamber of the balance oil cylinder (16). The piston rod of the oil cylinder (15) and the piston rod of the balance oil cylinder (16) are rigidly connected with the boom (17); The A port of the three-position four-way electromagnetic reversing valve (27) is connected to the hydraulic accumulator (18), the B port of the three-position four-way electromagnetic reversing valve (27) is connected to the fuel tank, and the three-position four-way electromagnetic reversing valve The P port and T port of (27) are respectively connected with the two cavities of the quantitative hydraulic motor (28), and the quantitative hydraulic motor (28), the third motor/generator (30), the reducer (31) and the turntable (32) mechanically connected; The outlet of the variable hydraulic pump/motor (4) is connected to the oil inlet of the one-way valve (8), and the oil outlet of the one-way valve (8) is connected to the P port and the P1 port of the boom multi-way valve (7); One motor/generator (2) is electrically connected with the first motor controller (26), the second motor/generator (23) is electrically connected with the second motor controller (24), and the third motor/generator ( 30) being electrically connected to the third motor controller (29), the first motor controller (26), the second motor controller (24), and the third motor controller (29) being electrically connected to the storage battery (25); Port B of the two-position two-way electromagnetic reversing valve (21) is connected to the quantitative pump/motor (22), the quantitative pump/motor (22) is connected to the second electric motor/generator (23), and the two-position two-way electromagnetic reversing The A port of the valve (21) is connected with the hydraulic accumulator (18), the P port of the hydraulically controlled three-position four-way reversing valve (14), the pressure sensor (19), the safety valve (20) and the three-position four-way electromagnetic commutator. Connect to port A of valve (27). 2. A hydraulic excavator oil-electric-hydraulic hybrid drive system according to claim 1, characterized in that: it also includes other hydraulic systems (33), and other hydraulic systems (33) include stick drive systems, bucket drive systems As well as the walking drive system, the outlet of the variable hydraulic pump (5) is connected with other hydraulic systems (33). 3. A hydraulic excavator oil-electric-hydraulic hybrid drive system according to claim 1, characterized in that: the first motor/generator (2), the second motor/generator (23) and the third motor Each generator (30) is equipped with a sensor for measuring the rotating speed, and the sensor is a rotary transformer or a photoelectric encoder.