CN2604554Y - Load Sensing Hydraulics for Six-Way Multi-Way Valves - Google Patents

Abstract

The utility model discloses a load sensing hydraulic device for a six-way multi-way valve. A variable displacement pump with controllable displacement and a six-way multi-way valve can control multiple hydraulic loads. A pressure detection port is provided on the working oil port of the multi-way valve to detect the maximum load pressure of the system. On the bypass oil return road of the valve, a flow detection device is installed between the six-way multi-way valve group and the hydraulic oil tank, which can detect the flow of hydraulic oil flowing through the bypass oil line of the six-way multi-way valve and returning to the oil tank. Since the flow detection element is set on the bypass oil return road, the throttling loss of the bypass can be controlled to a small value; and because the load pressure is detected in the device, the output pressure of the hydraulic pump can be controlled, It effectively reduces the throttling loss of the bypass and realizes the "pressure adaptation" control, so that the device can better adapt to the load change during operation, further reduces the power loss and improves the reliability.

Description

Load Sensing Hydraulics for Six-Way Multi-Way Valves

Technical field

The utility model relates to the control of a hydraulic pump, a pumping device or a system, and is a load sensing hydraulic device used for the control of a six-way multi-way valve.

Background technique

In most hydraulically driven mechanical equipment such as hydraulic excavators and cranes, the hydraulic circuit includes at least one hydraulic pump and a multi-way valve. Among them, the hydraulic pump provides the pressure oil to drive the mechanical equipment, and the multi-way valve is located between the hydraulic pump and the actuator to control the flow and direction of the hydraulic oil, thereby controlling the movement direction and speed of the actuator.

According to whether the displacement of the hydraulic pump used in the hydraulic system is variable, the hydraulic system of this "pump-valve-actuator" mode can be divided into a quantitative system and a variable system. Whether it is a quantitative system or a variable system, there are inevitably various forms of power loss inside, such as throttling loss, overflow loss, leakage loss, etc. Among them, throttling loss and leakage loss account for most of the power loss in operation. Due to the existence of these power losses, the hydraulic system is seriously heated, which not only wastes energy, causes environmental pollution, but also seriously affects the reliability of the whole machine.

Because the variable hydraulic system can better adapt to the load power demand of the mechanical equipment at work, it has higher efficiency and better energy saving than the quantitative hydraulic system. Therefore, most of the modern high-power hydraulic mechanical equipment adopts the variable hydraulic system, which can effectively Eliminates the various hydraulic power losses described above. According to the control strategy of the variable pump, the variable system can be divided into constant power system, negative flow control system, flow demand control system and load sensing control system. In these systems, the constant power system, negative flow control system and flow demand control system mostly use three-position six-way multi-way valves, while the load sensing control system mostly uses three-position four-way (excluding load sensing holes) type Multi-way valve. The purpose of the valve control strategy adopted in these systems is to reduce or eliminate the various throttling losses, leakage losses and overflow losses mentioned above.

In the constant power system, the hydraulic pump can make full use of the engine power under various load conditions without overloading the engine, and has been widely used in construction machinery. On hydraulically driven mechanical equipment with the same working capacity, compared with the quantitative system, the constant power system can use an engine with a lower rated power. Under the condition of the same working point of the driving device, the constant power system is also more efficient than the constant power system, reflecting a certain degree of energy saving. In the constant power system, a constant power hydraulic pump and a three-position six-way multi-way valve are used. The working point (pressure and displacement) of the hydraulic pump is located on the constant power curve, and the pump displacement decreases with the increase of the load pressure. . When the spool of the multi-way valve is in the middle position, the system is naturally in an unloaded state; when working, rely on the bypass throttling effect to increase the pump output pressure, so as to overcome the resistance to work. The advantages of this system are simple structure, mature multi-way valve manufacturing process, no additional unloading circuit, and full use of engine power. Its main disadvantage is that the bypass throttling loss is relatively large. When the system pressure is not enough to overcome the load resistance, all the power of the engine is consumed on the heat of the hydraulic system.

In the flow demand control system, a positive flow control pump and a six-way multi-way valve are used, and the displacement of the pump is proportional to the valve core displacement of the multi-way valve. Its advantage is that the pump output flow is controlled by the pilot control pressure of the multi-way valve, which reduces the bypass throttling loss to a certain extent, but does not fundamentally solve this problem, and the loss is still relatively large under certain working conditions. No matter what kind of system, as long as the six-way multi-way valve is used, unless some measures are taken, bypass throttling loss will inevitably occur. When the system works for a long time, this loss is quite large. Negative flow control is an effective way to reduce this loss.

In the negative flow control system, a negative flow control pump and a six-way multi-way valve are used. The higher the pilot control pressure applied to the pump, the smaller the displacement. In this kind of system, since the flow detection element is installed on the bypass oil return passage of the multi-way valve (that is, the unloading passage), the bypass oil return flow can be controlled at a relatively low level by a certain pump displacement control strategy. small value. Since the hydraulic oil that produces bypass throttling loss will return to the oil tank through the bypass oil return circuit, while controlling the bypass oil return flow, the bypass throttling loss is also suppressed, which fundamentally solves the problem. In essence, the negative flow control is to use the flow detection element installed on the bypass oil return line to control the bypass oil return flow to a smaller value, which is a constant flow control. In order to achieve this purpose, the usual practice is to use the flow detection element to convert the flow signal into a pressure signal (this pressure represents the oil return flow of the bypass), and control this pressure signal to a constant value. No matter what kind of flow detection element is used, a direct consequence of this control is that the inlet pressure before the flow detection element is a constant value, and when the valve core is in the middle position, this pressure is equal to the output pressure of the pump. In order to easily overcome the load pressure and improve the stability of work, this pressure needs to be set at a higher value, which increases the burden on the system when it is not working, and also increases the leakage loss, making the hydraulic pump long-term Under high pressure working conditions.

In the load sensing hydraulic system, a load sensing pump and a four-way multi-way valve are used. Due to the adoption of a four-way multi-way valve, there is no bypass oil return passage, which completely eliminates the throttling loss of bypass oil return. Not only that, under the load sensing control strategy, the pump output pressure is always higher than the maximum load pressure by a small fixed value, so that the pump output pressure always adapts to the maximum load pressure. Under load sensing control, the working speed of the actuator can also be well controlled. Therefore, load sensing control can be summed up as "pressure adaptation (load), flow controllable". Regardless of energy saving or maneuverability, the load sensing hydraulic system has better performance. Its disadvantage is that the structure of the multi-way valve and the load sensing pump is complicated and the cost is high, which limits its popularization.

To sum up, in the existing energy-saving control methods of hydraulic systems, some have complex structures and high costs, such as load sensing control systems; some cannot effectively eliminate bypass throttling losses, such as constant power systems and flow demand Control system; although the negative flow control system can better eliminate the oil return loss of the bypass and can better control the working speed of the actuator, it lacks the pressure adaptation control function like the load sensing control.

Contents of Invention

The purpose of this utility model is to provide a load sensing hydraulic device for a six-way multi-way valve. A pressure detection port is set at the working oil port of the six-way multi-way valve, and a flow detection element is set on the bypass oil return road. Reduce bypass throttling loss and realize pressure adaptive control.

The utility model uses a variable displacement pump with controllable displacement and a six-way multi-way valve, which can control multiple hydraulic loads. The working oil port of the multi-way valve is provided with a pressure detection port, which can detect the highest load pressure of the system. On the bypass oil return road of the multi-way valve, a flow detection device is installed between the six-way multi-way valve group and the hydraulic oil tank, which can detect the flow of hydraulic oil flowing through the bypass oil circuit of the six-way multi-way valve and returning to the oil tank. . It can control the inlet pressure of the flow detection device on the bypass oil circuit so that it is always a small fixed value higher than the maximum load pressure of the system, and when the inlet pressure of the flow detection device reaches a certain limit set in the pump controller After the value is reached, the pump controller controls the inlet pressure of the flow detection device to maintain this limit value.

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

The output port of the hydraulic pump is divided into two routes, one route passes through two load-holding check valves and enters the P port of the first-level multi-way valve and the second-level multi-way valve respectively, and the A port and B port of the two multi-way valves are respectively connected to the two The rodless valve of the hydraulic cylinder is connected with the rod cavity, the T ports of the two multi-way valves are connected with the oil tank, the Q port of the first-level multi-way valve is connected with the O port of the second-level multi-way valve, and the Q port of the second-level multi-way valve is The inlet of the flow detection element is connected through the hydraulic pipeline, while the outlet of the flow detection element is connected with the oil tank, and at the same time connected with the pump controller through the pressure signal path, connecting the hydraulic pressure of the rod chamber and the rodless chamber of the two hydraulic cylinders. The pipes are respectively connected to the two input ports of the first shuttle valve and the second shuttle valve, the output ports of the two shuttle valves are connected to the two input ports of the third shuttle valve, and the output of the third shuttle valve is passed through the pressure The signal pipeline is connected with the pump controller, and the output of the pump controller is connected with the pilot pressure input port of the hydraulic pump through the pressure signal path.

In order to achieve the "pressure adaptation" control of the hydraulic pump while eliminating the throttling loss of the bypass, a pressure detection port is set at the working oil port of the six-way multi-way valve to detect the load pressure of each working device; a maximum pressure detection network is set , and connected to the above-mentioned pressure detection port to detect the highest load pressure in each working device; a flow detection element (usually used orifice) to convert the flow signal into a pressure signal. On the basis of this structure, first select the maximum load pressure value in each working device as a reference value, and add a small fixed value on the basis of this reference pressure value (in order to be able to reliably overcome the load pressure), and the sum after the addition is taken as the target value. The second step is to detect the pressure value at the inlet of the bypass return oil flow detection element, and through the control of the displacement of the hydraulic pump, the pressure value can change with the change of the target value.

Compared with the background technology, the utility model has the beneficial effects that:

Since the flow detection element is set on the bypass oil return road, the throttling loss of the bypass can be controlled to a small value; and because the load pressure is detected in the device, the output pressure of the hydraulic pump can be controlled, Therefore, in the six-way multi-valve hydraulic system, the organic combination of reducing bypass throttling loss and "pressure adaptation" control is effectively realized, so that the hydraulic system can better adapt to the requirements of load changes during operation, which not only greatly reduces the Power loss, and significantly reduces leakage loss, reduces energy consumption, and is conducive to environmental protection. At the same time, the working intensity of the device is also reduced, and the reliability is improved.

Description of drawings

Fig. 1 is a structural principle diagram of the utility model;

Figure 2 is a schematic diagram of negative flow load sensing represented by simplifying the six-way multi-way valve into three linked variable throttle valves;

Fig. 3 is a structural block diagram of the pump controller;

Fig. 4 is a structural block diagram of a PI controller in the pump controller in Fig. 3;

Fig. 5 is the schematic diagram of implementing the utility model by adopting computer control technology and electro-hydraulic proportional control technology;

Fig. 6 is a structural block diagram of realizing the pump controller with electronic technology;

Fig. 7 is a characteristic diagram of positively controlling the hydraulic pump;

Fig. 8 is a characteristic diagram of a negative control hydraulic pump;

Fig. 9 is a graph of the relationship between the passing flow and the pressure when the fixed orifice is used as the flow detection element (assuming that the outlet of the flow detection element directly leads to the hydraulic oil tank).

In the figure, 1. variable hydraulic pump, 1A. hydraulic system, 2. hydraulic cylinder, 2A. hydraulic cylinder, 3. multi-way valve, 3A. multi-way valve, 3b. multi-way valve control handle, 3a. multi-way valve control Handle, 3c. Multi-way valve working port 1, 3d. Multi-way valve working port 2, 3e. Multi-way valve bypass return port (or called multi-way valve bypass port), 3f. Multi-way valve Spool, 4. Bypass oil return flow detection element, 5. System bypass oil return passage (or called bypass oil passage), 6. Pressure signal passage, 7. Maximum load pressure signal passage, 8. Pump controller , 8A.PI controller, 8B. Proportional operation unit, 8C. Integral operation unit, 8D saturation link, 8E. Electronic pump controller, 8a. Microprocessor, 8b.A/D converter, 8c.A/D conversion Device, 8d D/A converter, 8e voltage/current (V/I) converter, 9. Fuel tank, 10. Shuttle valve, 10A. Shuttle valve, 10B. Shuttle valve, 11. Load holding check valve, 11A. Load holding check valve, 12. Hydraulic pump pilot control pressure signal path, 13. Pressure sensor, 13A. Pressure sensor, 14. Electro-hydraulic proportional pressure reducing valve.

Detailed ways

In Fig. 1, the output port of the hydraulic pump 1 is connected to the input of the load holding check valves 11 and 11A on the one hand, and is also connected to the O port of the primary multi-way valve. In this way, the hydraulic oil output by the hydraulic pump is divided into two parts, and one part enters the P port of the multi-way valve through the load holding check valves 11 and 11A. The A port and B port of the multi-way valve are respectively connected with the rodless cavity and the rod cavity of the hydraulic cylinder, and the T port is connected with the fuel tank. According to the position of the valve core of the multi-way valve, the pressure oil at the P port is output from the A port or the B port, enters the hydraulic cylinder, and then drives the hydraulic cylinders 2 and 2A; The outlet flows back to the fuel tank. The Q port of the first-stage multi-way valve 3 is connected with the O port of the second-stage multi-way valve 3A, and the Q port of the second-stage multi-way valve 3A is connected with the inlet of the flow detection element 4 through the hydraulic pipeline 5, and the flow detection element 4 The outlet of the fuel tank 9 links to each other. Therefore, another part of the pressure oil output by the hydraulic pump is input to the O port of the first-stage multi-way valve 11, then output from the Q port, enters the O port of the second-stage multi-way valve 11A, and then flows from the second-stage multi-way valve 11A The Q port output, returns to the hydraulic oil tank 9 through the bypass oil circuit 5 and the flow detection element 4. Because the inlet of the flow detection element 4 is also connected to the pump controller 8 through the pressure signal line 6 , the pressure P _o at the inlet of the flow detection element 4 is sent to the pump controller 8 through the pressure signal line 6 . The hydraulic pipes connecting the rod cavity and the rodless cavity of the hydraulic cylinder are also respectively connected with two input ports of a shuttle valve, so that the shuttle valve outputs the highest pressure of the hydraulic cylinder. For example, the shuttle valve 10 outputs the maximum pressure of the hydraulic cylinder 2; the shuttle valve 10B outputs the maximum pressure of the hydraulic cylinder 2A. The outputs of shuttle valves 10 and 10B are in turn coupled to the two inputs of a third shuttle valve 10A so that shuttle valve 10A outputs the higher of the two input pressures. In this way, the maximum load pressure P _max can be detected by the shuttle valve group composed of shuttle valves 10, 10B and 10A, and output by the shuttle valve 10A. The output of the shuttle valve 10A is connected to the pump controller 8 through the pressure signal line 7 . The output of the pump controller 8 is connected with the pilot pressure input port of the hydraulic pump 1 through the pressure signal passage 12 . Therefore, the pump controller 8 generates a control pressure P _c under the negative flow load sensing control strategy, and sends it to the pilot pressure input port of the pump through the pressure signal channel 12 to control the change of the pump displacement.

Figure 1 is an expandable system, which is expanded by cascading six-way multi-way valves. In Fig. 1, only one stage of multi-way valve 3A is expanded to control hydraulic cylinder 2A. Similarly, on this basis, more multi-way valves can be expanded to control more hydraulic cylinders. The P port of the newly expanded multi-way valve is still connected to the outlet of the hydraulic pump 1 through a load holding check valve and hydraulic pipeline, the O port is connected to the Q port of the upper-stage multi-way valve through the hydraulic pipeline, and the flow detection element 4. It is always between the Q port of the last stage multi-way valve and the hydraulic oil tank. The T port is still connected to the oil tank. The A port and the B port are still respectively connected to the two ports of the hydraulic actuator (such as a hydraulic cylinder). Take off the maximum load pressure with the shuttle valve.

Fig. 2 has further illustrated the principle of the utility model. In the figure, the six-way multi-way valve 3 (assuming the multi-way valve is in the right position) is equivalent to three linked variable throttle ports 3c, 3d, 3e and valve core 3f, where the inlet of 3c is equivalent to the multi-way valve’s Port P, the outlet is equivalent to the A port of the multi-way valve; the inlet of 3d is equivalent to the O port of the multi-way valve, and the outlet is equivalent to the Q port of the multi-way valve; the inlet of 3e is equivalent to the B port of the multi-way valve, and the outlet is equivalent to On the T port of the multi-way valve. The flow detection element 4 is still located between the Q port of the last stage multi-way valve and the fuel tank 9 . When the multi-way valve 3 is in the middle position, the bypass oil port 3d is fully opened, and the output flow of the pump returns to the oil tank 9 through the bypass oil circuit 5 and the flow detection element 4, while the working oil ports 3c and 3e are fully closed. With the movement of the valve core 3b, the working oil ports 3c and 3e are gradually opened synchronously while the multi-way valve is gradually changing to the right position, while the bypass oil port 3d is gradually closed synchronously. During this process, the displacement of the hydraulic pump 1 is controlled by the pump controller 8, so that the inlet pressure P _o of the flow detection element 4 is always kept at a level higher than the maximum load pressure P _max transmitted by the pressure signal channel 7. The fixed value of ΔP. In this way, when the system is not working, the system load pressure P _max is small, and under the action of the pump controller 8, the inlet pressure in front of the flow detection element 4 is also small, and since the bypass oil port 3d is fully opened at this time, therefore The output pressure of the hydraulic pump 1 is also low, and is in a state of small flow and low pressure. With the movement of the valve core 3b, when the system enters the working state, the maximum load pressure P _max of the system detected in the pressure signal channel 7 gradually increases, and under the action of the pump controller 8, the inlet pressure P _o of the flow detection element 4 also increases. gradually increases, the output pressure of the corresponding hydraulic pump 1 also gradually increases. In this process, since the bypass oil port 3d gradually decreases and the working oil port 3c gradually opens, in order to ensure that the inlet pressure P _o of the flow detection element 4 can keep up with the change of the maximum load pressure P _max , the hydraulic pump 1 Only increase the flow rate under the effect of the pump controller 8. By reasonably selecting the parameters of the flow detection element 4 and the pump controller 8, the hydraulic oil flow back to the oil tank through the bypass oil circuit 5 can be very small (this is the principle of reducing the bypass throttling loss), so the hydraulic pump 1 increases The flow of all enters the hydraulic cylinder 2, which is used to speed up the speed of the actuator, which is also the principle of the speed control of this system. In the control process, when P _o increases to a certain extent, it will not increase, and it will be maintained at this maximum value under the action of the pump controller.

FIG. 3 is a functional diagram of the pump controller 8 . The core of the pump controller 8 is a PI controller 8A, which receives the maximum load pressure signal P _max and the inlet pressure signal P _o of the bypass flow detection element 4, wherein P _max is used as a command signal, and P _o is used as a feedback signal. In this way, the pump controller, the hydraulic pump and the hydraulic system 1A composed of the multi-way valve 3, 3A and the bypass flow detection element 4 constitute a closed-loop control system, and the inlet pressure _Po of the bypass flow detection element 4 is the system output, And the maximum load pressure P _max is the system input. The sum generated by the addition of P _max and ΔP passes through a saturation link 8D, and then the difference e generated by subtracting P _o (that is, the control error) is used as the input of the PID controller 8A, and the output of the PID controller 8A is used as the hydraulic pump 1 pilot control pressure P _c to control its output flow Q, and then control the output pressure of the entire closed-loop system——P _o . If the saturation value of the saturation link 8D is set as P _o(max) , then under the action of the pump controller, the maximum value that the inlet pressure P _o of the bypass flow detection element 4 can reach is P _o(max) .

FIG. 4 is a block diagram of the PI controller 8A. In the figure, the control error e is sent to two computing units at the same time, one is the proportional computing unit 8B, and the other is the integral computing unit 8C. Therefore, the relationship between the input quantity e of the PI controller and the output quantity P _c is as follows: $P_c=K_P\·e+K_I\&Center\; Dot;{\∫}_0^t\mathrm{edt}$ In the formula: K _P ——proportional operation constant, K _I ——integral operation constant. The output quantity P _c is used to control the output flow of the hydraulic pump 1 .

Figure 5 is an implementation example realized by using electro-hydraulic proportional technology and computer technology. In the figure, the pump controller 8 is composed of an electronic pump controller 8E, pressure sensors 13 and 13A, and an electro-hydraulic proportional pressure reducing valve 14 . The maximum load pressure P _max and the inlet pressure P _o of the bypass flow detection element 4 are converted into voltage signals by the pressure sensors 13A and 13, respectively. The pressure sensors 13A and 13 are connected with the electronic pump controller 8E by wires, so the electronic pump controller can receive the maximum load pressure P _max and the inlet pressure P _o of the bypass flow detection element 4 . The output of the electronic pump controller 8E is connected with the current input end of the electro-hydraulic proportional decompression valve 14 , and the pressure output end of the electro-hydraulic proportional decompression valve 14 is connected with the pilot pressure input end of the hydraulic pump 1 . In this way, the output signal of the electronic pump controller 8E is output in the form of current, which is used as the input of the electro-hydraulic proportional pressure reducing valve 14, and the electro-hydraulic proportional pressure reducing valve 14 converts the input current signal into a hydraulic control signal P _c , Used to control the output flow of hydraulic pump 1. The bypass flow detection element 4 is implemented in the form of a fixed orifice, and its inlet pressure P _o represents the size of the bypass return oil flow Q _o , the relationship between the two is shown in Figure 9. The hydraulic pump 1 can either adopt a positive control method in which the flow rate Q increases with the increase of the pilot pressure _Pc (this kind of pump is called a positive control _pump ), as shown in Figure 7; Increase and decrease negative control mode (this kind of pump is called negative control pump), as shown in Figure 8. When hydraulic pumps with different control forms are used, the algorithms of the pump controller 8 are also different. In the above implementation scenario, it is assumed that a positive control pump is used.

式中：K_P——比例运算常数，K_I——积分运算常数，P_cmax——负控制液压泵的最大先导压力输入。输出量P_c用来控制液压泵1的输出流量。When the hydraulic pump 1 adopts the negative control hydraulic pump, the relationship between the input quantity e and the output quantity _Pc of the PI controller in Fig. 4 should be corrected as follows:

In the formula: K _P ——proportional operation constant, K _I ——integral operation constant, P _cmax ——maximum pilot pressure input of negative control hydraulic pump. The output quantity P _c is used to control the output flow of the hydraulic pump 1 .

FIG. 6 is a structural block diagram of the pump controller in FIG. 5 . The highest load pressure signal _Pmax and the inlet pressure signal _Pc of the bypass flow detection element 4 are converted into electrical signals by the pressure sensors 13A and 13, and then converted into electrical signals by the A/D converters 8b and 8c in the electronic pump controller 8E The digital signal is then sent to the microprocessor 8a for PID calculation. The result obtained by the calculation is sent to the D/A converter 8d to be converted into a voltage signal, and then the voltage signal is converted into a current signal through the V/I converter 8e (the output current value is proportional to the input voltage value), which is used to drive The electro-hydraulic proportional pressure reducing valve 14 is used to generate the corresponding control pressure P _c , so that the maximum load pressure signal P _max and the inlet pressure signal P _o of the bypass flow detection element 4 maintain the following relationship:

P _o ＝P _max +ΔP P _o ≤P _o(max) In the formula, ΔP is a very small pressure value set in the algorithm of the pump controller, and P _o(max) is the internal saturation link of the electronic pump controller 8E Set the saturation value.

Claims (4)

1. the load sensing hydraulic pressure installation that is used for six-way multiple unit valve, it is characterized in that it comprises: the delivery outlet at oil hydraulic pump (1) is divided into two-way, two loads of leading up to keep one-way valve (11), (11A) enter one-level multi-way valve (3) respectively, the P mouth of secondary multi-way valve (3A), the A mouth of two multi-way valve and B mouth respectively with two oil hydraulic cylinders (2), rodless cavity (2A) links to each other with rod chamber, the T mouth of two multi-way valve links to each other with fuel tank, the Q mouth of one-level multi-way valve (3) links to each other with the O mouth of secondary multi-way valve (3A), the Q mouth of secondary multi-way valve (3A) links to each other with the inlet of flow detecting element (4) by hydraulic pipe line (5), the outlet of flow detecting element (4) then links to each other with fuel tank (9), link to each other with pump controller (8) by pressure signal path (6) simultaneously, connect two oil hydraulic cylinders (2), on the rod chamber (2A) and the hydraulic tube of rodless cavity separately with first shuttle valve (10), two inlet openings of second shuttle valve (10B) connect, two shuttle valves (10), delivery outlet (10B) links to each other with two inlet openings of the 3rd shuttle valve (10A), the output of the 3rd shuttle valve (10A) links to each other with pump controller (8) by pressure signal pipeline (7), and the output of pump controller (8) links to each other with the pilot pressure inlet opening of oil hydraulic pump (1) by pressure signal path (12).

2. the load sensing hydraulic pressure installation that is used for six-way multiple unit valve according to claim 1 is characterized in that: said pump controller (8) is a PI controller (8A), comprises a scale operation unit (8B) and an integral arithmetic unit (8C).

3. the load sensing hydraulic pressure installation that is used for six-way multiple unit valve according to claim 1, it is characterized in that: said pump controller (8) comprises electronic pump controller (8E), first pressure transducer (13) and second pressure transducer (13A), electro-hydraulic proportional reducing valve (14); The output of electronic pump controller (8) links to each other with the current input terminal of electro-hydraulic proportional reducing valve (14), and the pressure output end of electro-hydraulic proportional reducing valve (14) links to each other with the pilot pressure input end of oil hydraulic pump (1).

4. the load sensing hydraulic pressure installation that is used for six-way multiple unit valve according to claim 1, it is characterized in that: said pump controller (8) comprises microprocessor (8a), A/D converter (8b), A/D converter (8c), D/A converter (8d), V/I transducer (8e); The end of A/D converter (8b), (8c) connects pressure transducer (13) and (13A) respectively, another termination microprocessor (8a), and microprocessor (8a) connects electro-hydraulic proportional reducing valve (14) through D/A converter (8d), V/I transducer (8e).

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