CN206958033U - A kind of digital load-sensitive hydraulic control architectures - Google Patents

Abstract

The utility model discloses a digital load sensitive hydraulic control structure. The digital flow source is used to control the multi-actuator system. Each actuator in the multi-actuator system is equipped with its own digital flow source. Each digital flow source is connected and controlled by its own digital load-sensitive oil circuit. Both ends of the device; the digital flow source adopts a hydraulic free piston engine, and the digital load sensitive oil circuit includes a hydraulic cavity, a three-position four-way electromagnetic proportional valve, a hydraulic cylinder, a first pressure sensor, a second pressure sensor, and a third pressure sensor , speed sensor, load sensing controller and load speed controller. The utility model overcomes the disadvantage of low efficiency when a single high-power engine drives a relatively low load in the traditional load-sensitive system. The utility model matches each actuator with a suitable hydraulic free-piston engine, so that the system has high hydraulic source efficiency, Hydraulically driven actuators have the advantages of high efficiency and fast system response.

Description

A Digital Load Sensing Hydraulic Control Structure

technical field

The utility model relates to a load sensitive hydraulic structure, in particular to a digital load sensitive hydraulic control structure.

Background technique

The traditional load sensing hydraulic system consists of a variable pump, a throttling element, an actuator, and a load sensing circuit. The load sensing circuit uses hydraulic feedback or electronic signal feedback to keep the difference between the system pressure and the maximum load pressure constant by adjusting the displacement of the variable pump. The pressure difference across the throttling element of the actuator with the maximum load pressure is constant, and there is a pressure reducing valve in front of the throttling element of other actuators to ensure a constant pressure difference at both ends. The system adjusts the flow rate by adjusting the opening area of the throttling element. The biggest advantage of the traditional load sensing system is that the pressure of the pump can adapt to the change of the highest load pressure in real time, so the pressure loss is small; and this is realized by adjusting the displacement of the hydraulic pump instead of using the overflow of the relief valve. Therefore, the throttling loss of the system is small.

As shown in Figure 1, the traditional load sensing system also has some shortcomings in the multi-actuator system: First, there is a large throttling loss for the actuator of the single-pump multi-actuator system that is not the maximum load pressure. Second, the single-pump multi-actuator system uses a powerful engine and a variable pump. Since the multi-actuator does not work under the maximum load at the same time, the variable pump often works at a lower displacement and the engine load is lower. The overall efficiency of the system is low. Three, when the load pressure and flow suddenly increase, the displacement of the hydraulic pump increases, and the output pressure increases. Due to the large moment of inertia of the engine, the dynamic response is slow, and the engine output speed and torque cannot quickly adapt to changes in load conditions.

Utility model content

In order to solve the problems existing in the background technology, the purpose of this utility model is to propose a digital load-sensitive hydraulic control structure, which can be applied to construction machinery, agricultural machinery, etc., and uses a hydraulic free-piston engine to solve the dynamic response speed of the traditional load-sensitive hydraulic structure Slow, low efficiency and other issues.

The technical scheme that the utility model adopts is as follows:

The utility model adopts a digital flow source to control the multi-actuator system. Each actuator in the multi-actuator system is equipped with its own digital flow source, and each digital flow source is connected through its own digital load-sensitive oil circuit. And control the two ends of the actuator, so as to realize the energy saving of each actuator and improve the efficiency of the overall structure.

On the one hand, the combination of a single digital flow source and a digital load-sensitive oil circuit has the characteristics of small size, fast response, high efficiency of hydraulic source, and high efficiency of hydraulic actuator compared with a single high-power engine and large displacement variable pump. On the one hand, the combination of multiple digital flow sources and digital load-sensitive oil circuits still has the advantage of high overall efficiency at lower loads than a single high-power engine.

The digital flow source is a flow source with discontinuous output waveform. Preferably a PWM waveform is used.

In a specific implementation, the actuator is an oil cylinder.

The digital flow source adopts a hydraulic free piston engine, and the digital load sensitive oil circuit includes a hydraulic cavity, a three-position four-way electromagnetic proportional valve, a hydraulic cylinder, a first pressure sensor, a second pressure sensor, a third pressure sensor, a speed Sensors, load sensing controllers and load speed controllers, the oil inlet of the hydraulic free piston engine is connected to the oil tank, the oil outlet of the hydraulic free piston engine is connected to the hydraulic chamber, the hydraulic chamber is connected to the valve of the three-position four-way electromagnetic proportional valve Port P connection, the valve port A of the three-position four-way electromagnetic proportional valve is connected to the rodless cavity of the hydraulic cylinder, the valve port B of the three-position four-way electromagnetic proportional valve is connected to the rod cavity of the hydraulic cylinder, and the three-position four-way electromagnetic proportional valve The valve port T of the valve is connected to the fuel tank; install the first pressure sensor at the valve port P of the three-position four-way electromagnetic proportional valve, install the second pressure sensor at the valve port A of the three-position four-way electromagnetic proportional valve, and install the second pressure sensor at the valve port A of the three-position four-way electromagnetic proportional valve. The third pressure sensor is installed on the valve port B of the electromagnetic proportional valve, and the first pressure sensor, the second pressure sensor and the third pressure sensor are connected to the load sensing controller, and the load sensing controller is connected to the control end of the hydraulic free piston engine; A speed sensor is installed on the piston rod of the cylinder, and the speed sensor is connected with the three-position four-way electromagnetic proportional valve through the load speed controller.

The hydraulic free piston engine involved in the utility model is a composite power device which integrates an internal combustion engine and a hydraulic pump, uses liquid as a working medium, and utilizes the pressure of liquid flow to realize non-rigid transmission of power. It eliminates the need for the crankshaft assembly in the internal combustion engine that converts the reciprocating motion of the piston into rotary motion in the traditional internal combustion engine-driven variable hydraulic pump hydrostatic compound drive system and the variable hydraulic pump (piston pump) that converts rotary motion into hydraulic pump pistons. The reciprocating swash plate assembly directly rigidly connects the piston of the internal combustion engine to the piston of the hydraulic pump.

The aforementioned hydraulic free-piston engine is essentially a digital flow source, and the load-sensing controller can control the output of the hydraulic free-piston engine through PWM signals.

The following methods are used to control the flow and speed in the load sensing control loop and the load speed control loop respectively:

For the load sensitive control circuit: use the first pressure sensor to collect the pressure of the valve port P of the three-position four-way electromagnetic proportional valve as the system pressure, and use the second pressure sensor and the third pressure sensor to collect the pressure of the three-position four-way electromagnetic proportional valve respectively The pressure of port A and valve port B, the larger value of the pressure of valve port A and valve port B is taken as the load pressure; when the difference between the system pressure and the load pressure becomes larger, the output signal is sent out through the load sensing controller to control the hydraulic pressure. The free-piston engine reduces the average output flow in a single cycle, so that the input flow of the hydraulic chamber becomes smaller, while the output flow of the hydraulic chamber remains unchanged; when the difference between the system pressure and the load pressure becomes smaller, the load-sensing controller sends out The output signal controls the hydraulic free-piston engine to increase the average output flow in a single cycle, so that the input flow of the hydraulic chamber increases, while the output flow of the hydraulic chamber remains unchanged.

For the load speed control loop: when the difference between the given speed and the speed of the hydraulic cylinder piston rod collected by the speed sensor becomes smaller, the three-position four-way electromagnetic proportional valve is controlled by the output signal of the load speed controller to reduce the opening of the valve port P. When the pressure difference between the two ends remains constant, the speed of the piston rod of the hydraulic cylinder decreases; when the difference between the given speed and the speed of the piston rod of the hydraulic cylinder collected by the speed sensor becomes larger, the load speed The output signal of the controller controls the three-position four-way electromagnetic proportional valve to increase the opening of the valve port P, so that the speed of the piston rod of the hydraulic cylinder increases under the condition that the pressure difference between the two ends remains unchanged.

When the piston rod of the hydraulic cylinder stretches out, the three-position four-way electromagnetic proportional valve is controlled by the load speed controller so that the valve port P and the valve port A communicate; when the piston rod of the hydraulic cylinder retracts inward, the load speed control The controller makes the three-position four-way electromagnetic proportional valve make the valve port B communicate with the valve port T; when the piston rod of the hydraulic cylinder does not need to move, the load speed controller makes the three-position four-way electromagnetic proportional valve in the neutral position.

The load sensing controller sends a PWM waveform output signal to the hydraulic free-piston engine to control the output flow of the hydraulic free-piston engine.

Therefore, the utility model combines the advantages of the load-sensing control technology and the digital hydraulic technology to form a digital load-sensing hydraulic control structure. On the one hand, the structure of the utility model adjusts the output of the hydraulic free piston engine through the feedback of the system pressure and the load pressure, so that the system pressure can adapt to the load pressure; on the other hand, it controls the opening of the three-position four-way electromagnetic proportional valve through the speed feedback of the hydraulic cylinder. to regulate load flow.

As shown in Figure 2, the utility model is equipped with a hydraulic free piston engine with matching power and digital load sensitive control technology for the multi-actuator system and each actuator, which can not only realize the energy saving of each actuator, Moreover, it overcomes the disadvantage of reduced efficiency when a single high-power engine drives a relatively low load in the traditional structure, and improves the efficiency of the overall structure.

The beneficial effects of the utility model are:

The utility model overcomes the disadvantage of low efficiency when a single high-power engine drives a lower load in the traditional load-sensitive structure. The utility model matches each actuator with a suitable hydraulic free-piston engine, so that the structure has the following advantages:

1. The efficiency of the hydraulic source is high. Compared with the traditional engine variable pump mechanism, the crank connecting rod mechanism is reduced, and the mechanical efficiency is improved. The engine of the single pump and single actuator system can better match the load and have higher efficiency;

2. The hydraulically driven actuator has high efficiency. According to the load sensing technology, the system pressure is slightly higher than the load pressure, and the throttling loss is small;

3. The structural response speed is fast, the piston inertia of the hydraulic free piston engine is small, and the response speed is fast;

4. The engine can be turned off when idling to improve fuel economy.

Description of drawings

Figure 1 is a schematic diagram of a traditional load-sensing hydraulic structure.

Fig. 2 is a schematic diagram of the digital load-sensing hydraulic structure of the present invention.

Fig. 3 is a specific implementation structure diagram of Embodiment 1 of the present utility model.

Fig. 4 is a specific implementation structural diagram of Embodiment 2 of the present utility model.

In the figure: 1. Hydraulic free piston engine, 2. Hydraulic chamber, 3-1, first pressure sensor, 3-2, second pressure sensor, 3-3, third pressure sensor 4, load speed controller, 5 , Three-position four-way electromagnetic proportional valve, 6. Hydraulic cylinder, 7. Speed sensor, 8. Load sensing controller, 9. Fuel tank, 10. Boom cylinder, 11. Stick cylinder, 12. Bucket cylinder, 13. Rolling oil cylinder, 14, lifting oil cylinder.

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment the utility model is described in further detail.

As shown in Figure 1, the specific implementation of the utility model includes a hydraulic free piston engine 1, a hydraulic pressure chamber 2, a three-position four-way electromagnetic proportional valve 5, a hydraulic cylinder 6, a fuel tank 9, a first pressure sensor 3-1, a second pressure The sensor 3-2, the third pressure sensor 3-3, the speed sensor 7, the load sensitive controller 8 and the load speed controller 4, the oil inlet of the hydraulic free piston engine 1 is connected to the oil tank 9, the oil of the hydraulic free piston engine 1 The outlet is connected to the hydraulic chamber 2, the hydraulic chamber 2 is connected to the valve port P of the three-position four-way electromagnetic proportional valve 5, and the valve port A of the three-position four-way electromagnetic proportional valve 5 is connected to the rodless chamber of the hydraulic cylinder 6. The valve port B of the four-position electromagnetic proportional valve 5 is connected to the rod cavity of the hydraulic cylinder 6 as an actuator, and the valve port T of the three-position four-way electromagnetic proportional valve 5 is connected to the oil tank 9; in the three-position four-way electromagnetic proportional valve The first pressure sensor 3-1 is installed on the valve port P of 5, the second pressure sensor 3-2 is installed on the valve port A of the three-position four-way electromagnetic proportional valve 5, and the second pressure sensor 3-2 is installed on the valve port B of the three-position four-way electromagnetic proportional valve 5 The third pressure sensor 3-3, the first pressure sensor 3-1, the second pressure sensor 3-2 and the third pressure sensor 3-3 are connected to the hydraulic free piston engine 1 through the load sensitive controller 8; A speed sensor 7 is installed on the piston rod, and the speed sensor 7 is connected with the three-position four-way electromagnetic proportional valve 5 through the load speed controller 4.

The first pressure sensor 3-1, the second pressure sensor 3-2 and the third pressure sensor 3-3 collect actual pressure signals and input them to the load sensing controller 8, and the output signal of the load sensing controller 8 controls the output of the hydraulic free piston engine 1 . The speed sensor 7 collects the actual speed signal of the piston rod of the hydraulic cylinder 6 and inputs it into the load speed controller 4, and the output of the load speed controller 4 controls the position and opening of the three-position four-way electromagnetic proportional valve 5.

The implementation work process of the present utility model is as follows:

For load sensing control loops

The first pressure sensor 3-1 collects the pressure at the valve port P of the three-position four-way electromagnetic proportional valve 5, that is, the system pressure. The second pressure sensor 3-2 and the third pressure sensor 3-3 respectively collect the pressures of the valve port A and valve port B of the three-position four-way electromagnetic proportional valve 5, and compare to obtain the larger value of the two, and the larger value is the load pressure.

When the difference between the system pressure and the load pressure becomes larger, the input signal of the load-sensing controller 8 increases, and the output signal of the load-sensing controller 8 decreases to reduce the average output flow of the hydraulic free-piston engine 1 in one cycle, and the hydraulic capacity The input flow of chamber 2 becomes smaller, while the output flow of hydraulic chamber 2, that is, the load flow remains unchanged. From the above formula (1) (2), it can be seen that the system pressure decreases, and the difference between the system pressure and the load pressure becomes smaller.

When the difference between the system pressure and the load pressure becomes smaller, the input signal of the load-sensing controller 8 decreases, and the load-sensing controller 8 appropriately increases the output signal to increase the average output flow of the hydraulic free-piston engine 1 in one cycle, and the hydraulic chamber The input flow of the hydraulic chamber increases, while the output flow of the hydraulic chamber, that is, the load flow, remains unchanged. From the above formula (1) (2), it can be seen that the system pressure increases, and the difference between the system pressure and the load pressure becomes larger.

It can be seen that the load sensitive control loop of the utility model is a negative feedback control, so that the system pressure always matches the load pressure.

The above-mentioned load sensing controller 8 controls the output flow of the hydraulic free piston engine 1 by PWM control. The period of the output signal of the load sensing controller 8 is constant, and the average output flow of the hydraulic free piston engine 1 within one period is controlled by changing the duty cycle of the signal.

For the load speed control loop

During the working process of the system, when the difference between the given speed and the speed of the hydraulic cylinder 6 piston rod becomes smaller, the input signal of the load speed controller 4 becomes smaller, and the load speed controller 4 reduces the output signal to reduce the three-position four-way The opening of the valve port P of the electromagnetic proportional valve, under the condition that the pressure difference between the two ends remains unchanged, it can be seen from the above formula (3) that the flow rate flowing through the valve port P of the three-position four-way electromagnetic proportional valve decreases, so that the hydraulic cylinder The speed of the piston rod decreases.

When the difference between the given speed and the speed of the hydraulic cylinder 6 piston rod becomes larger, the input signal of the load speed controller 4 becomes larger, and the load speed controller 4 increases the output signal to increase the valve port of the three-position four-way electromagnetic proportional valve The opening degree of P, under the condition that the pressure difference between the two ends remains unchanged, from the above formula (3), it can be seen that the flow rate flowing through the valve port P of the three-position four-way electromagnetic proportional valve increases, so that the speed of the piston rod of the hydraulic cylinder increases. big.

In addition, when the piston rod of the hydraulic cylinder 6 stretches out, the load speed controller 4 makes the three-position four-way electromagnetic proportional valve 5 in the left position, so that the valve port P communicates with the valve port A; when the piston rod of the hydraulic cylinder 6 When retracting inwardly, the load speed controller 4 makes the three-position four-way electromagnetic proportional valve 5 in the right position, so that the valve port B and the valve port T are connected; when the piston rod of the hydraulic cylinder 6 does not need to move, the load speed controller 4 Make the three-position four-way electromagnetic proportional valve 5 in the neutral position.

Embodiments of the present utility model are as follows:

Example 1:

Applying the utility model to the working device of the excavator, as shown in Figure 3, for the boom cylinder 10, the arm cylinder 11 and the bucket cylinder 12, respectively match the hydraulic free piston engine with appropriate power and the corresponding digital Load sensitive oil circuit.

When the boom cylinder 10, arm cylinder 11 and bucket cylinder 12 need to move, it is only necessary to turn on the corresponding hydraulic free piston engine 1 and control the corresponding three-position four-way solenoid valve 5.

Therefore, the system pressure in the hydraulic circuit of each cylinder matches the load pressure, and because of the structural advantages of the hydraulic free-piston engine 1, the overall efficiency of the structure is higher than that of the traditional load-sensing structure.

If a traditional single high-power engine and a large-displacement variable pump are used to drive three oil cylinders: the system pressure can only adapt to the oil cylinder with the highest load pressure, and the difference between the system pressure and the load pressure of the other two oil cylinders is large. The throttling loss of the control valves in front of the two oil cylinders is relatively large; since the three oil cylinders are not always in the maximum working condition at the same time, the overall output power of the high-power engine and the large-displacement variable pump is low, so the high-power engine and The overall efficiency of large displacement variable displacement pumps is low.

In this embodiment, each of the three oil cylinders is matched with a hydraulic free piston engine with appropriate power and corresponding digital load control oil circuit. The system pressure at the outlet of the three hydraulic free-piston engines can adapt to the load pressure of the three oil cylinders, and the structural throttling loss is small; the movements of the three oil cylinders are controlled by their respective hydraulic free-piston engines and corresponding digital load control oil circuits. The rated power of the free-piston engine matches the maximum working condition of the cylinder, so the overall efficiency of the hydraulic free-piston engine is high, and the hydraulic free-piston engine can be turned off at idle speed to improve fuel economy.

Example 2:

Applying the utility model to the working device of the wheel loader, as shown in Figure 4, the hydraulic free-piston engine and the corresponding digital load-sensitive oil circuit with appropriate power are respectively matched with the tilting cylinder 13 or the lifting cylinder 14 .

When the roll cylinder 13 or the lift cylinder 14 needs to move, it is only necessary to turn on the corresponding hydraulic free piston engine 1 and control the corresponding three-position four-way solenoid valve 5 . Therefore, the system pressure in the hydraulic circuit of each cylinder matches the load pressure, and because of the structural advantages of the hydraulic free-piston engine 1, the overall efficiency of the structure is higher than that of the traditional load-sensing structure.

If a traditional single high-power engine and a large-displacement variable pump are used to drive two cylinders: the system pressure can only adapt to the cylinder with a higher load pressure, and the difference between the system pressure and the load pressure of the other cylinder is large, and the cylinder with a lower load The throttling loss of the control valve in front of the oil cylinder is relatively large; because the two oil cylinders are not always in the maximum working condition at the same time, the overall output power of the high-power engine and the large-displacement variable pump is low, so the high-power engine and large displacement pump The overall efficiency of variable displacement pumps is low.

However, in the present embodiment, each of the two oil cylinders is matched with a hydraulic free-piston engine with appropriate power and a corresponding digital load control oil circuit. The system pressure at the outlet of the two hydraulic free-piston engines can adapt to the load pressure of the two oil cylinders, and the structural throttling loss is small; the movement of the two oil cylinders is controlled by their own hydraulic free-piston engines and corresponding digital load control oil circuits. The rated power of the free-piston engine matches the maximum working condition of the cylinder, so the overall efficiency of the hydraulic free-piston engine is high, and the hydraulic free-piston engine can be turned off at idle speed to improve fuel economy.

The above-mentioned specific embodiments are used to explain the utility model, rather than to limit the utility model. Within the spirit of the utility model and the scope of protection of the claims, any modifications and changes made to the utility model fall into the scope of the utility model. scope of protection.

Claims (1)

1. A kind of 1. digital load-sensitive hydraulic control architectures, it is characterised in that：Multi executors are controlled using digital fluid source System, each actuator in multi executors system are equipped with connecting respective digital fluid source, each digital fluid Source connects through respective digital load sensitivity oil circuit and controls the both ends of actuator；

   Described actuator uses hydraulic cylinder (6), and described digital fluid source uses hydraulic free-piston engine (1), number Word load-sensitive oil circuit includes hydraulic pressure cavity volume (2), 3-position 4-way electromagnetic proportional valve (5), hydraulic cylinder (6), first pressure sensor (3-1), second pressure sensor (3-2), the 3rd pressure sensor (3-3), velocity sensor (7), Ioad-sensing control device (8) With loading speed controller (4), the fluid entrance connection fuel tank (9) of hydraulic free-piston engine (1), hydraulic free-piston hair The fluid outlet of motivation (1) is connected with hydraulic pressure cavity volume (2), the valve port P of hydraulic pressure cavity volume (2) and 3-position 4-way electromagnetic proportional valve (5) Connection, the valve port A of 3-position 4-way electromagnetic proportional valve (5) are connected with the rodless cavity of hydraulic cylinder (6), 3-position 4-way electromagnetic proportional valve (5) valve port B is connected with the rod chamber of hydraulic cylinder (6), and the valve port T of 3-position 4-way electromagnetic proportional valve (5) is connected with fuel tank (9)； First pressure sensor (3-1) is installed in the valve port P of 3-position 4-way electromagnetic proportional valve (5), in 3-position 4-way electromagnetic proportional valve (5) Valve port A installation second pressure sensor (3-2), 3-position 4-way electromagnetic proportional valve (5) valve port B install the 3rd pressure sensing Device (3-3), first pressure sensor (3-1), second pressure sensor (3-2) and the 3rd pressure sensor (3-3) are connected to Ioad-sensing control device (8), the control terminal of Ioad-sensing control device (8) connection hydraulic free-piston engine (1)；In hydraulic cylinder (6) installation rate sensor (7) on piston rod, velocity sensor (7) is through loading speed controller (4) and 3-position 4-way electromagnetism Proportioning valve (5) connects.