CN107906059A - A kind of high-pressure pump voltage-stabilizing system and method - Google Patents

Abstract

A voltage stabilizing system and method for testing a high-pressure hydraulic pump, the voltage stabilizing system includes a hydraulic pump under test, a high-pressure accumulator, a low-pressure accumulator, an accumulator switching device, a pressure sensor, a control unit, the high-pressure accumulator The accumulator is connected to the outlet oil circuit of the hydraulic pump, and the low-pressure accumulator is connected to the outlet oil circuit of the hydraulic pump through the accumulator switching device. After the hydraulic pump under test is turned on, the pressure sensor monitors the pressure of the oil circuit. When the pressure is less than the preset value, the oil enters the low-pressure accumulator through the accumulator switching device, and the low-pressure accumulator keeps the system pressure stable. When the pressure is greater than the preset value, the control part controls the accumulator switching device to switch, and the oil The road is cut off from the passage of the low-pressure accumulator, and the high-pressure accumulator keeps the system pressure stable.

Description

A system and method for stabilizing a high-pressure pump

technical field

The invention relates to a hydraulic pump stabilizing system, in particular to a high-pressure hydraulic pump testing stabilizing system and a usage method.

Background technique

At present, high-pressure hydraulic pumps generally adopt a plunger structure, so pressure and flow pulsations often occur in the hydraulic system. The pulsation can be reduced by connecting an accumulator at the outlet of the hydraulic pump. However, in the performance test of the high-pressure hydraulic pump, due to the The nominal pressure is very high, and the hydraulic pump factory test must be overloaded, which leads to a very large pressure regulation range of the entire oil system, even reaching 0-50Mpa. At present, a single accumulator is commonly used in the pump test hydraulic system. In the high-pressure test system, if the accumulator inflation pressure is low, although it can meet the pressure stabilization requirements of the system under low pressure conditions, but under high pressure conditions, the accumulator will exceed The load range will cause great damage to the accumulator, and there may even be a certain degree of danger. Conversely, if the accumulator inflation pressure is high, it can meet the pressure stabilization requirements of the system under high pressure, but when the system is under low pressure, the accumulator cannot absorb the pressure and flow pulsation of the high pressure pump well, which will affect the entire hydraulic system. The system has a certain impact.

Contents of the invention

The invention provides a voltage stabilizing system of a high-pressure hydraulic pump. The voltage stabilizing system includes a hydraulic pump to be tested, a high-pressure accumulator, a low-pressure accumulator, an accumulator switching device, a pressure sensor, and a control unit; The accumulator is connected to the outlet oil circuit of the hydraulic pump, and the low-pressure accumulator is connected to the outlet oil circuit of the hydraulic pump through the accumulator switching device. After the hydraulic pump under test is turned on, the pressure sensor monitors the pressure of the oil circuit. When the pressure is lower than the preset value, the oil enters the low-pressure accumulator through the accumulator switching device, and the low-pressure accumulator keeps the system pressure stable. When the pressure is higher than the preset value, the control part controls the accumulator switching device to switch, The oil circuit is cut off from the passage of the low-pressure accumulator, and the high-pressure accumulator keeps the system pressure stable.

When the accumulator switching device closes the oil circuit and the low-pressure accumulator passage, the passage between the low-pressure accumulator and the liquid tank is opened, and the remaining oil in the low-pressure accumulator returns to the liquid tank through this passage.

Preferably, the accumulator switching device adopts a pilot type electromagnetic reversing valve.

Preferably, the high-pressure accumulator and the low-pressure accumulator are precharged with different pressure values. For example, in a hydraulic system with a pressure regulation range of 0-50MPa, the pre-charge pressure value of the high-pressure accumulator is 30-40MPa, and the pre-charge value of the low-pressure accumulator is 30-40MPa. The filling pressure value is 15-25Mpa,

The present invention also provides a method for stabilizing pressure of a hydraulic pump, which is characterized in that: the oil circuit is connected with a high-pressure accumulator, a low-pressure accumulator, an electromagnetic reversing valve and a pressure sensor, and the high-pressure accumulator is connected to the outlet oil circuit of the hydraulic pump connected, the low-pressure accumulator is connected to the outlet oil circuit of the hydraulic pump through the electromagnetic reversing valve. The control method includes the following steps:

A The oil circuit is opened, the preset pressure value;

B No control signal is sent to the electromagnetic pilot valve that controls the action of the electromagnetic reversing valve spool, the electromagnetic reversing valve spool does not move, and the oil and low-pressure accumulator channels are opened;

C The pressure sensor monitors the current oil circuit system pressure. When the system pressure is lower than the set pressure, go to step D; when the system pressure is higher than the set pressure, go to step E;

D When the system pressure is lower than the set pressure, stop sending the control signal to the electromagnetic pilot valve that controls the action of the electromagnetic reversing valve spool, the passage between the system and the low-pressure accumulator is opened, and the oil enters the low-pressure accumulator through the electromagnetic reversing valve , the system maintains a stable pressure by the low-pressure accumulator;

E When the system pressure is greater than the preset value, a control signal is sent to the electromagnetic reversing valve that controls the action of the spool of the electromagnetic reversing valve. The channel between the tank and the liquid tank is opened, and the oil remaining in the low-pressure accumulator returns to the tank through this channel, and the pressure of the system is kept stable by the high-pressure accumulator;

F. Make a judgment, if the high-pressure pump under test does not stop working, repeat steps C to E, if the high-pressure pump stops working, go to step G;

G Stop sending control signals to the control electromagnetic reversing valve, the spool of the electromagnetic reversing valve resets, the channel between the low-pressure accumulator and the outlet of the hydraulic pump is opened, the low-pressure accumulator and the outlet of the hydraulic pump are connected, and the low-pressure accumulator and the hydraulic pump are connected. The path between the boxes is cut off.

Preferably, the electromagnetic reversing valve is a pilot type electromagnetic reversing valve.

Preferably, in the above step F, the host computer performs delay judgment.

In another embodiment, the accumulator switching device adopts an electromagnetic reversing valve with a double-spool structure, preferably a pilot-operated electromagnetic reversing valve with a double-spool structure. The pilot solenoid valve includes a first spool and a second spool, the inlet of the first spool is connected to the hydraulic pump outlet oil circuit, and the outlet is connected to the inlet of the second spool and the low-pressure accumulator, The inlet of the second spool communicates with the outlet of the first spool and the low-pressure accumulator, and the second spool still has a channel connected to the liquid tank, which is blocked in the initial state. The first spool controls on-off, and the second spool can discharge the residual liquid in the accumulator. When the pressure is greater than the preset value, the control unit controls the first spool to switch so that the oil passage and the low-pressure accumulator channel are blocked, and at the same time, the second spool switches to open the channel between the low-pressure accumulator and the liquid tank , the remaining oil in the low-pressure accumulator returns to the tank through the second spool.

Preferably, the two spool strings adopt an integrated structure and are connected to the valve body through a threaded sleeve.

Preferably, the control spool of the first spool is provided with an air hole, so as to prevent a closed air cavity from being formed between the inner cavity and the liquid sleeve during the action of pushing the spool, which cannot be reliably shut off.

In another embodiment, an electromagnetic reversing valve with a double-spool structure is used as the accumulator switching device, wherein the high-pressure accumulator and the low-pressure accumulator are connected in the oil circuit, including the first spool and the second spool The electromagnetic reversing valve and the pressure sensor, the high-pressure accumulator is connected to the outlet oil circuit of the hydraulic pump, and the low-pressure accumulator is connected to the outlet oil circuit of the hydraulic pump through the electromagnetic reversing valve. The voltage stabilization control method includes the following steps:

A The oil circuit is opened, the preset pressure value,

B No control signal is sent to the electromagnetic pilot valve that controls the action of the first spool and the second spool, the first spool and the second spool do not act, and the passage between the outlet oil of the hydraulic pump and the low-pressure accumulator is opened , the passage between the low-pressure accumulator and the liquid tank is cut off;

C The pressure sensor monitors the current oil circuit system pressure. When the system pressure is lower than the set pressure, go to step D. When the system pressure is higher than the set pressure, go to step E

D When the system pressure is lower than the set pressure, the electromagnetic pilot valve that controls the action of the first spool and the second spool stops sending control signals, the first spool and the second spool of the electromagnetic reversing valve do not act, and the hydraulic pressure The channel between the oil at the outlet of the pump and the low-pressure accumulator is opened, the channel between the low-pressure accumulator and the liquid tank is closed, the oil passes through the liquid passage hole of the first spool respectively, and the liquid passage between the first spool and the second spool Channel, the annular cavity outside the second spool enters the low-pressure accumulator, and the system maintains a stable pressure by the low-pressure accumulator;

E When the system pressure is greater than the preset value, the control system sends a control signal to the electromagnetic pilot valve that controls the action of the first spool, the first spool moves, the hydraulic pump outlet oil circuit and the low-pressure accumulator channel are cut off, and the oil stops entering Low-pressure accumulator, the system maintains pressure stability by the high-pressure accumulator, and at the same time sends a control signal to the electromagnetic pilot valve that controls the action of the second spool, the second spool moves, the channel between the low-pressure accumulator and the liquid tank is opened, and the low-pressure The remaining oil in the accumulator returns to the tank;

F. Make a judgment, if the high-pressure pump under test does not stop working, repeat steps C to E, if the high-pressure pump stops working, go to step G;

G Stop sending control signals to the electromagnetic reversing valve that controls the action of the first spool and the second spool, the first spool and the second spool are reset, the passage between the low-pressure accumulator and the outlet of the hydraulic pump is opened, The low-pressure accumulator is connected to the outlet of the hydraulic pump, and the passage between the low-pressure accumulator and the liquid tank is cut off.

Preferably, the electromagnetic reversing valve is a pilot type electromagnetic reversing valve.

Preferably, in the above step F, the host computer performs delay judgment.

The system voltage stabilization scheme for switching between high and low pressure accumulators in the present invention, by setting two accumulators with different pressure ranges, solves the problem that a single accumulator cannot well meet the testing requirements of the high pressure pump test hydraulic system, and realizes the low pressure accumulator It can automatically cut off and drain the energy when the system is under high pressure, so as to maintain the pressure stability of the hydraulic system under different pressure conditions.

In the present invention, the implementation scheme of double valve cores is adopted, and the structure is more compact; at the same time, if one of the electromagnetic pilot valves fails, the system pressure stability will not be greatly affected, and the system stability is higher. The electromagnetic pilot valve can be used to realize the automatic switching of the valve; the control valve core has air holes to ensure the reliable sealing between the valve core and the valve seat;

The entire voltage stabilization system is simple and reliable to build, combined with the host computer software, the automatic control of the entire hydraulic pressure stability can be realized, and the operation is convenient.

Description of drawings

Fig. 1 is the system schematic diagram of the first embodiment of the voltage stabilizing system tested by the disclosed hydraulic pump;

Fig. 2 is a flow chart of the method of the first embodiment of the voltage stabilizing system tested by the hydraulic pump of the present disclosure;

Fig. 3 is a system schematic diagram of the second embodiment of the voltage stabilizing system tested by the hydraulic pump of the present disclosure;

Reference signs:

1-High-pressure pump under test; 2-Drive motor; 3-Filter; 4-Low-pressure accumulator; 5-Pilot electromagnetic reversing valve; 6-Pressure sensor; 7-High-pressure accumulator; ; 9-cooler; 10-safety valve; 11-liquid tank.

12 pilot-operated double-spool electromagnetic reversing valve; 12-1 first spool; 12-2 second spool, 12-3 electromagnetic pilot valve that controls the action of the first spool; 12-4 controls the action of the second spool Solenoid pilot valve;

Detailed ways

The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are only some of the embodiments of the present disclosure, not all of them. Based on the embodiments in the present disclosure, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present disclosure.

Example 1

Fig. 1 is the schematic diagram of the voltage stabilizing system of hydraulic pump test of the present invention, and it mainly includes: 1-tested high-pressure pump; 2-drive motor; 3-filter; 4-low pressure accumulator; Reversing valve; 6-pressure sensor; 7-high pressure accumulator; 8-pressure regulating valve; 9-cooler; 10-safety valve; 11-liquid tank.

The driving motor 2 drives the tested high-pressure pump 1 to absorb liquid from the liquid tank 11, and the oil returns to the liquid tank after passing through the filter 3 pressure regulating valve 8 and the cooler 9; Accumulator 7 and a low-pressure accumulator 4, wherein a pilot type electromagnetic reversing valve 5 is connected in series in front of the low-pressure accumulator 4; at the same time, a pressure sensor 6 and a safety valve 10 are connected to the outlet of the high-pressure pump 1 under test.

Among them, the filter filters the oil, the pressure sensor feeds back the system pressure, cooperates with the upper computer software to realize the automatic control of the system, the cooler performs oil cooling, and the safety valve serves as the overload protection of the system.

Its hydraulic pump test system is realized by the following method, combined with the host computer software, its control process is shown in Figure 2:

The high-pressure pump 1 under test is started, and the system is in the no-load starting state. The preset pressure value is set in the software of the host computer. The valve 5 enters the low-pressure accumulator 4. Although the high-pressure accumulator 7 is always connected, due to its high inflation pressure, the system pressure will not cause a large deformation of the air bag. The low-pressure accumulator 4 with low pressure realizes the voltage stabilizing effect. Afterwards, it is judged in a loop in the software. When the system pressure is lower than the set pressure, no control signal is sent to the electromagnetic pilot valve of the pilot-operated electromagnetic reversing valve 5, and the system is still powered by the low-pressure accumulator 4 with low inflation pressure. Realize the function of stabilizing the pressure; when the system pressure is greater than the set pressure value, the upper computer sends a control signal to the electromagnetic pilot valve of the pilot electromagnetic reversing valve 5, the valve core changes direction, and the channel from the system to the low-pressure accumulator 4 is cut off. At the same time, the passage between the low-pressure accumulator 4 and the liquid tank is opened, and the oil remaining in the low-pressure accumulator 4 returns to the liquid tank through this passage. Energy device 7 maintains a stable pressure. Make a slight delay in the host computer software and continue to judge. If the tested high-pressure pump 1 stops working, the host computer stops sending control signals to the electromagnetic pilot valve of the electromagnetic reversing valve 5. If the tested high-pressure pump 1 does not stop working, Then return to continue looping to judge the relationship between the system pressure value and the preset pressure value.

Example 2

Referring to Fig. 3, other connections of the hydraulic system are the same as those in Embodiment 1. In this embodiment, the electromagnetic reversing valve uses a pilot-operated double-spool electromagnetic reversing valve 12, wherein the inlet of the first valve core 12-1 is connected to the tested The outlet of the high-pressure pump 1 is connected, the outlet is connected to the low-pressure accumulator 4 and the inlet of the second valve core 12-2, and the outlet of the second valve core 12-2 is connected to the liquid tank 11. Wherein the first spool is responsible for on-off, and the second spool makes the liquid in the low-pressure accumulator return to the liquid tank.

The voltage stabilization scheme of its hydraulic pump test system is realized by the following voltage stabilization scheme. First, the tested high-pressure pump 1 is started, and the system is in the no-load startup state. The preset pressure value is set in the host computer software. The reversing valve 12 controls the electromagnetic pilot valve 12-3 that controls the action of the first spool and the electromagnetic pilot valve 12-4 that controls the action of the second spool does not send control signals, and its first spool 12-1 and second spool 12 -2 does not act, the oil passes through the first spool 12-1, and enters the low-pressure accumulator 4. Although the high-pressure accumulator 7 is always connected, due to its high inflation pressure, the system pressure will not make the air bag less Large deformation, at this time, the system uses the low-pressure accumulator 4 with low inflation pressure to stabilize the system. Afterwards, the judgment is made cyclically in the software. When the system pressure is lower than the set pressure value, the upper computer controls the electromagnetic pilot valve 12-3 of the pilot type double-spool electromagnetic reversing valve 12 and the electromagnetic pilot valve 12-3 that controls the action of the first spool and the second control valve. The electromagnetic pilot valve 12-4 with the spool action still does not send a control signal, and the system still uses the low-pressure accumulator 4 with low inflation pressure to realize the pressure stabilization function; when the system pressure reaches or exceeds the preset pressure value, through the host computer software Send control signals to the pilot-operated double-spool electromagnetic reversing valve 12, which controls the action of the first spool, and the electromagnetic pilot valve 12-4, which controls the action of the second spool, and the first spool 12-1 changes direction, the channel from the system to the low-pressure accumulator 4 is closed, and at the same time, the second spool 12-2 changes direction, and the remaining oil in the low-pressure accumulator 4 returns to the liquid tank through the second spool 12-2. At this time, the low-pressure The accumulator 4 is cut off, and the system maintains a stable pressure by the high-pressure accumulator 7. Make a slight delay in the host computer software and continue to judge. If the tested high-pressure pump 1 stops working, the host computer stops sending control signals to the electromagnetic pilot valve of the electromagnetic reversing valve 5. If the tested high-pressure pump 1 does not stop working, Then return to continue looping to judge the relationship between the system pressure value and the preset pressure value.

The first spool spool string and the second spool spool string adopt an integrated structure, are connected by screws, and are connected with the valve body by a threaded sleeve, which is convenient for disassembly and assembly. Two solenoid pilot valves are designed in one valve block to form a solenoid pilot valve.

When the system is working, the port P is connected to the outlet of the high-pressure pump under test. When the system is in a low-pressure state, the oil passes through the port P, and passes through the liquid hole of the first valve core valve stem and the liquid hole of the first valve core valve core screw sleeve. , Channel A enters the low-pressure accumulator, and the system maintains a stable pressure by the low-pressure accumulator. Combined with the host computer software, when the system pressure is higher than the set pressure, control signals are sent to the two electromagnets of the electromagnetic pilot valve 28 at the same time, and the oil at port P enters the electromagnetic pilot valve through the filter, and passes through the electromagnetic pilot valve. After reversing, it enters the control ports K1 and K2 respectively, among which the oil at the K1 port enters the control chamber, where it acts on the annular end surface of the control chamber at the lower end of the first spool control spool, and its force is greater than that acting on the control chamber of the first spool. The force of the annular end surface of the upper end of the spool pushes the first spool to control the spool to move upwards and press it against the first valve seat. Here, the first spool controls the spool to have air holes to prevent the first spool from During the upward movement of the control spool, a closed air cavity is formed between the inner cavity of the control spool and the stem of the first spool, so that the control spool of the first spool cannot be pressed tightly onto the seat of the first spool. Port P and the low-pressure accumulator cannot be reliably cut off. At this time, the P port and the first spool spool threaded sleeve are cut off, and the oil cannot enter the low-pressure accumulator; at the same time, the control fluid at the K2 port acts on the control end of the second spool valve stem, and the second spool The valve stem overcomes the spring force of the spring, so that the liquid passage hole of the second valve sleeve is connected with the liquid passage hole of the valve stem of the second valve core, and the remaining oil in the low-pressure accumulator passes through port A, the liquid passage hole of the second valve sleeve and The second spool valve rod is connected through the liquid hole and returns to the liquid tank through the T port. At this time, the system maintains a stable pressure by the high-pressure accumulator. When the system pressure is lower than the set pressure, it stops sending control signals to the solenoid pilot valve, there is no control fluid at the K1 and K2 ports, the first spool control spool resets under the action of the P port pressure, and the P port and the low-pressure energy storage The channel between the devices is opened, and at the same time, the valve stem of the second valve core is pressed against the valve seat of the second valve core under the action of the spring force, so that the low-pressure accumulator and the T-port channel are blocked, and the system is restarted by the low-pressure accumulator. Keep the pressure steady.

The advantage of adopting the double spool structure in the second embodiment is that if the electromagnetic pilot valve controlling the action of the first spool fails, when the system pressure is greater than the set pressure, the control part will control the action of the first spool and the second spool. The electromagnetic pilot valve sends control signals at the same time. At this time, the first spool does not act due to the failure of the electromagnetic pilot valve that controls the action of the first spool. When the high-pressure oil from the hydraulic pump returns to the liquid tank through this channel, the low-pressure accumulator is protected; if the electromagnetic pilot valve that controls the action of the second spool fails, when the system pressure is greater than the set pressure, the control part sends The electromagnetic pilot valve that controls the actions of the first spool and the second spool sends a control signal at the same time, and the first spool changes direction, so that the hydraulic pump outlet oil circuit and the low-pressure accumulator channel are cut off, and the system is stabilized by the high-pressure accumulator. At this time, the second spool does not act due to the failure of the electromagnetic pilot valve that controls the action of the second spool, and the direct passage between the low-pressure accumulator and the liquid tank cannot be opened, so that a part of the oil will remain in the low-pressure accumulator , when the system pressure is lower than the set value or the system stops working, the control part stops sending control signals to the electromagnetic pilot valve that controls the action of the first spool and the second spool, the first spool resets, the low-pressure accumulator and the hydraulic pressure The passage of the pump outlet oil circuit is conducted, and the oil remaining in the low-pressure accumulator is discharged back to the oil tank through the system;

The above embodiments are only suitable for illustrating the present disclosure, rather than limiting the present disclosure. Those of ordinary skill in the relevant technical fields can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, all Equivalent technical solutions also belong to the category of the present disclosure, and the patent protection scope of the present disclosure should be defined by the claims.

Claims (8)

1. a kind of voltage-stabilizing system of high-pressure hydraulic pump, the voltage-stabilizing system includes hydraulic pump, high pressure accumulator, low pressure accumulator, Accumulator switching device, pressure sensor, control unit；The high pressure accumulator is connected with hydraulic pump outlet oil circuit, the low pressure Accumulator switches switching valve by accumulator and is connected with hydraulic pump outlet oil circuit, after the subject hydraulic pump is opened, pressure sensing Device monitors oil circuit pressure, and when pressure is less than preset value, fluid enters low pressure accumulator by accumulator switching device, stored by low pressure Energy device maintains system pressure to stablize, and when pressure is more than preset value, control unit controls the accumulator switching device to switch over, oil Road is ended with the low pressure accumulator passage, maintains system pressure to stablize by high pressure accumulator.

2. the voltage-stabilizing system of high-pressure hydraulic pump as claimed in claim 1, it is characterised in that：The accumulator switching device is first Conductivity type solenoid directional control valve.

3. the voltage-stabilizing system of high-pressure hydraulic pump as claimed in claim 1 or 2, it is characterised in that：High pressure accumulator Preliminary pressure-filled It is 15-25Mpa to be worth for 30-40MPa, low pressure accumulator preacceleration inflation force value.

4. the voltage-stabilizing system of high-pressure hydraulic pump as claimed in claim 2, it is characterised in that：The type pilot solenoid directional control valve is Bivalve cored structure, including the first spool and the second spool, first cartridge inlet are connected with hydraulic pump outlet oil circuit, and outlet connects Lead to second cartridge inlet and the low pressure accumulator, second cartridge inlet then with first cartridge outlet and described Low pressure accumulator connects.

5. the voltage-stabilizing system of high-pressure hydraulic pump as claimed in claim 6, it is characterised in that：Described two spool strings are using one Formula structure, is connected by swivel nut with valve body；It is preferred that it is provided with stomata on the control spool of the first spool.

A kind of 6. hydraulic pump method for stabilizing voltage, it is characterised in that：High pressure accumulator, low pressure accumulator, electromagnetic switch are connected in oil circuit Valve and pressure sensor, high pressure accumulator are connected with hydraulic pump outlet oil circuit, and low pressure accumulator passes through solenoid directional control valve and liquid Press pump outlet oil circuit is connected.Control method comprises the following steps：

A oil circuits are opened, preset pressure value；

B does not send control signal to the electromagnetic priority valve of control electromagnetic switch valve core action, and electromagnetic switch valve core is failure to actuate, Fluid is opened with low pressure accumulator passage；

The current oil circuit system pressure of C pressure Sensor monitoring, when system pressure is less than setting pressure, goes to step D, works as system When pressure is higher than setting pressure, step E is gone to；

D stops sending control to the electromagnetic priority valve of control electromagnetic switch valve core action when system pressure is less than setting pressure Signal processed, system are opened with low pressure accumulator passage, and fluid enters low pressure accumulator by solenoid directional control valve, and system is stored by low pressure Can device maintenance pressure stability；

E is more than preset value when system pressure, and control signal, electricity are sent to the solenoid directional control valve of control electromagnetic switch valve core action Magnetic change-over valve core commutates, and the passage of system and low pressure accumulator ends, and the passage between low pressure accumulator and liquid case is opened, low Remaining fluid returns to liquid case by this passage in pressure accumulator, and system maintains pressure stability by high pressure accumulator；

F. judged, if high-pressure pump is not stopped, repeat step C to E, if high-pressure pump is stopped, carries out step G；

G stops sending control signal, solenoid directional control valve valve core reset to control solenoid directional control valve, and low pressure accumulator is pumped out with hydraulic pressure The passage of mouth is opened, and low pressure accumulator is turned on hydraulic pump outlet, and path ends between low pressure accumulator and liquid case.

A kind of 7. method for stabilizing voltage of hydraulic pump, it is characterised in that：Connect high pressure accumulator in oil circuit, low pressure accumulator, including The solenoid directional control valve and pressure sensor of one spool and the second spool, high pressure accumulator is connected with hydraulic pump outlet oil circuit, low Accumulator is pressed to be connected by solenoid directional control valve and hydraulic pump outlet oil circuit, voltage stabilizing control method comprises the following steps：

A oil circuits are opened, preset pressure value,

B does not send control signal to the electromagnetic priority valve of the first spool of control and the action of the second spool, first spool and Second spool is failure to actuate, and hydraulic pump outlet fluid is opened with low pressure accumulator passage, path between low pressure accumulator and liquid case Cut-off；

The current oil circuit system pressure of C pressure Sensor monitoring, when system pressure is less than setting pressure, goes to step D, works as system When pressure is higher than setting pressure, step E is gone to；

D stops hair when system pressure is less than setting pressure to the electromagnetic priority valve of the first spool of control and the action of the second spool Control signal is sent, the first spool of solenoid directional control valve and the second spool are all failure to actuate, and hydraulic pump outlet fluid leads to low pressure accumulator Road is opened, and path ends between low pressure accumulator and liquid case, and fluid passes through the first spool liquid pass hole, the first spool and second respectively Liquid passage is crossed between spool, the annular chamber outside the second spool enters low pressure accumulator, and system maintains pressure by low pressure accumulator Stablize；

E is more than preset value when system pressure, and control letter is sent to the electromagnetic priority valve of control the first spool action by control system Number, the first spool action, hydraulic pump outlet oil circuit ends with low pressure accumulator path, and fluid stops entering low pressure accumulator, is System maintains pressure stability by high pressure accumulator, while sends control signal to the electromagnetic priority valve of control the second spool action, the Two spools act, and passage is opened between low pressure accumulator and liquid case, and remaining fluid returns to liquid case in low pressure accumulator；

F. judged, if high-pressure pump is not stopped, repeat step C to E, if high-pressure pump is stopped, carries out step G；

G stops sending control signal to the solenoid directional control valve of the action of the first spool of control and control the second spool action, and described the The passage of one spool and the second valve core reset, low pressure accumulator and hydraulic pump outlet is opened, low pressure accumulator and hydraulic pump outlet Conducting, path ends between low pressure accumulator and liquid case.

Preferably, solenoid directional control valve is type pilot solenoid directional control valve.

A kind of 8. method for stabilizing voltage of hydraulic pump such as claim 6 or 7, it is characterised in that：Preferably, in above-mentioned steps F, on Position machine carries out delay judgement.