CN117628241A - Combined valve capable of actively deflating - Google Patents

Abstract

The invention provides a combined valve capable of actively discharging gas, which belongs to the technical field of mechanical design, and comprises a shell and a valve body positioned in the shell, wherein the valve body comprises an electromagnetic valve, the rear end of the electromagnetic valve is directly connected with a pressure reducing valve, the pressure reducing valve is connected with a one-way valve, the one-way valve is communicated with an outlet, a safety valve is arranged between the one-way valve and the outlet, an active gas discharging passage for discharging leakage gas outwards is arranged on the shell, and the active gas discharging passage is positioned between an electromagnetic valve gas discharging passage and an inlet of the pressure reducing valve, so that the leakage gas of the electromagnetic valve can be actively discharged in a power-off state, and the normal work of the combined valve in the power-on state and the normal work of an emergency energy system are not influenced.

Description

Combined valve capable of actively deflating

Technical Field

The invention belongs to the technical field of mechanical design, and particularly relates to a combined valve capable of actively deflating.

Background

To ensure the airworthiness and safety of the aircraft, the aircraft is usually designed with one or more emergency energy systems to ensure that the aircraft is still controllable in the event of a conventional power failure. The use envelope of the emergency energy system coincides with the flight envelope of the aircraft, and the use requirements should be met under all flight altitude conditions. One of the important components of the emergency energy system is a combined valve, and the combined valve has the functions of reducing the pressure of the high-pressure gas at the front end to a proper pressure under the condition of power-on to push the fuel in the fuel tank at the rear end, and then the fuel enters a decomposition chamber to be catalytically decomposed into high-temperature high-pressure fuel gas, so that a turbine is pushed to do work, and the power of the output shaft is obtained. Referring to fig. 1, the combination valve is formed by integrating a solenoid valve, a pressure reducing valve, a check valve and a safety valve assembly in the same housing. The device has two working states, namely a power-off state and a power-on state. Under the condition of power failure, the electromagnetic valve is in a closed state under the combined action of spring force and medium pressure; the pilot gas path controlled by the electromagnetic valve is in a closed state under the combined action of the spring force and the medium pressure; the decompression valve cavity is not filled with medium at the moment, and is in an open state under the action of spring force, and the one-way valve and the safety valve are both in a closed state under the action of spring force.

In the related art, in order to meet the requirement of quick starting of an emergency energy system, the peak flow of a product is required to be large, and the response is quick, so that the electromagnetic valve adopts a pilot structure, the opening and closing of the main valve are realized by the on-off of a pilot gas channel, and the opening and closing of the pilot gas channel are controlled by an electromagnetic coil. After the product is electrified, the electromagnet component overcomes the spring force and the medium pressure, and the pilot gas channel is opened; the introduced working medium opens the reversing valve, so that the main gas path is smooth; the working medium enters the throttle orifice of the pressure reducing valve, the product is output after the pressure is reduced, the pressure is supplied to the rear end of the pressure reducing valve, meanwhile, the working medium is fed back to the pressure reducing valve cavity after the pressure is reduced, the opening of the pressure reducing valve is regulated in real time according to the change of the pressure of the medium by the pressure sensing component in the pressure reducing valve, and the output pressure is ensured to meet the requirement.

The combined valve has the advantages that the electromagnetic valve of the combined valve cannot be completely sealed due to the fact that the working pressure is high and the requirement is high, internal leakage exists, leakage gas cannot be discharged outwards in a power-off state, the pressure of a fuel tank pressure gauge at the rear end of the combined valve is increased, the system working is affected, meanwhile, the risk of false start exists, and the labor cost, the economic cost and the time cost of aircraft maintenance are increased.

Disclosure of Invention

In order to solve the problems that in the prior art, an electromagnetic valve of a combination valve cannot be completely sealed, leakage gas cannot be discharged outwards in a power-off state, so that the pressure of a fuel tank pressure gauge at the rear end of the combination valve is increased, the system work is influenced, meanwhile, the risk of false start exists, and the labor cost, the economic cost and the time cost of aircraft maintenance are increased, the invention provides the combination valve capable of actively discharging the leakage gas of the electromagnetic valve in the power-off state, and meanwhile, the normal work of the power-on state of the combination valve and the normal work of an emergency energy system are not influenced. The technical scheme is as follows:

the utility model provides a but combination valve of initiative gassing, including the casing and be located the valve body of casing, the valve body includes the solenoid valve, and the solenoid valve rear end links directly with the relief valve, and the relief valve links to each other with the check valve, and the check valve intercommunication export is equipped with the relief valve between check valve and the export, is equipped with the initiative gassing passageway 19 that makes the leakage gas outwards discharge on the casing, and initiative gassing passageway 19 is located between solenoid valve exhaust passageway B and relief valve entry C.

Because the left valve of the electromagnetic valve corresponds to the position of the exhaust passage B of the electromagnetic valve and is coaxial, when the electromagnetic valve is electrified, the left valve of the electromagnetic valve moves along the axis in the direction close to the exhaust passage B of the electromagnetic valve, the active air release passage 19 is sealed by the left valve of the electromagnetic valve, and the active air release passage 19 does not influence the normal operation of the combined valve when the electromagnetic valve is electrified;

when the power is off, the left valve of the electromagnetic valve moves along the axis in a direction away from the exhaust passage B of the electromagnetic valve, and the active air discharging passage 19 is communicated with the atmosphere through the exhaust passage B of the electromagnetic valve, so that the air leaked by the valve of the main passage of the electromagnetic valve can be discharged outwards through the active air discharging passage 19 and the exhaust passage B of the electromagnetic valve, thereby protecting the fuel tank at the rear end of the combined valve, preventing the pressure of the fuel tank from rising and preventing the fuel tank from being started by mistake; the labor cost, the economic cost and the time cost of aircraft maintenance are reduced.

Wherein, the horizontal distance between the active air release passage 19 and the central line of the electromagnetic valve mounting hole is 6-8mm, the central line of the active air release passage 19 and the central line of the electromagnetic valve mounting hole are on the same plane and are 15-25 degrees.

Wherein, the shell 8 is perforated by adopting an electric spark mode to form an active air discharging passage 19, and the length of the active air discharging passage 19 is 10-12mm.

Wherein the active venting passage 19 has a diameter of 0.2-0.6mm. When energized, the active bleed passage 19 is an order of magnitude smaller in diameter than the main passage of the solenoid valve, so the active bleed passage 19 shunts very little, with negligible impact on the response time of the main passage opening of the solenoid valve.

The inlet of the combined valve shell is provided with a high-density multi-layer filter, so that impurities, foreign matters and the like in the medium can be effectively filtered, and the conditions that the combined valve is blocked and cannot be opened due to the fact that the impurities and the foreign matters enter the internal channel of the combined valve are avoided.

In the combined valve capable of actively deflating, a main passage, a pilot gas passage, an exhaust passage and an active deflation passage are arranged in the electromagnetic valve, the active deflation passage in the electromagnetic valve is connected with the exhaust passage and the rear end of the electromagnetic valve, the main passage is a high-pressure gas passage, the pilot gas passage is used for introducing a stream of gas from the main passage, the right valve of the electromagnetic valve is used for opening the pilot gas passage under the action of electromagnetic force, so that the pressure of the gas in the inner cavity of the main passage of the electromagnetic valve is reduced, and the valve of the main passage of the electromagnetic valve is opened under the action of gas pressure difference to open the main passage. The electromagnetic valve exhaust passage plays a role in exhausting gas of the first gas guiding passage and then releasing pressure when the power is off.

The electromagnetic valve comprises an electromagnetic valve right valve, an electromagnetic valve rod assembly and an electromagnetic valve left valve, the electromagnetic valve left valve is connected with the electromagnetic valve right valve through the electromagnetic valve rod assembly and the sealing ring, one side of the electromagnetic valve right valve is closed, one side of the electromagnetic valve right valve is opened, and meanwhile, the middle cavity is sealed.

The sealing ring is arranged on the contact surface of the solenoid valve rod and the shell, the solenoid valve further comprises an armature and a coil, the solenoid valve left valve, the solenoid valve right valve and the solenoid valve rod assembly are arranged on the same horizontal plane, and the center line is overlapped with the center line of the solenoid valve coil and the armature.

The electromagnetic valve rear end of the combination valve is directly connected with the pressure reducing valve, the pressure reducing valve is provided with a main passage and a pressure sensing passage, the main passage of the pressure reducing valve can reduce high-pressure gas from the upstream electromagnetic valve to required pressure through the pressure sensing throttling assembly, and meanwhile, the pressure sensing passage can adjust the opening degree of the pressure reducing valve in real time according to the change of the pressure at the rear end, and the output pressure at the rear end is adjusted.

The pressure reducing valve is connected with the one-way valve, the one-way valve is communicated with the outlet, and the one-way valve only allows media to pass through in one direction.

A safety valve is arranged between the one-way valve and the outlet, the safety valve plays a role in overpressure protection, and when the output pressure of the pressure reducing valve is overlarge, the safety valve is opened in an emergency mode, so that the normal operation of the system can be prevented from being damaged due to overlarge pressure.

The shell of the combined valve is made of titanium alloy TC4 material, has lighter weight and good performances of high and low temperature resistance, mechanical load resistance and corrosion resistance.

The invention has the beneficial effects that:

1) According to the invention, the active air release passage is added on the basis of the traditional combination valve, so that when the valve of the main passage of the electromagnetic valve leaks under the condition of long-term sealing at high pressure, leakage medium is actively discharged, the condition that the medium enters a rear-end system to cause the system pressure to exceed the standard is avoided, and the safety of aircraft personnel is ensured;

2) The active air release passage of the combined valve adopts small holes of 0.2-0.6mm by adopting electric spark processing, so that the normal work of the combined valve in an electrified state is not influenced;

3) The 40 mu m high-density multilayer filter is arranged at the inlet of the combination valve, so that the pollution resistance of the traditional combination valve is improved;

4) The shell of the combined valve is made of titanium alloy TC4 material, can bear 28MPa pressure at maximum, is lighter in weight, has good high and low temperature resistance, mechanical load resistance and corrosion resistance, and has a compact overall structure.

Drawings

Fig. 1 is a schematic diagram of the principles of the present invention.

FIG. 2 is a schematic diagram of the power-off state structure of the present invention.

Fig. 3 is a schematic view of the structure of the power-on operation state of the present invention.

FIG. 4 is a schematic view of the active bleed passage horizontal position of the present invention.

FIG. 5 is a cross-sectional view of an active bleed passage of the present invention.

The valve comprises a right valve of a 1-electromagnetic valve, a valve rod component of a 2-electromagnetic valve, a left valve of a 3-electromagnetic valve, a 4-armature, a 5-coil, a 6-decompression valve cavity, a 7-bellows spring component, an 8-shell, a 9-valve sleeve component, a pressure sensing passage of a 10-decompression valve, a valve of a 11-one-way valve, a spring of a 12-one-way valve, a valve of a 13-safety valve, a spring of a 14-safety valve, a valve of a 15-decompression valve, a spring of a main passage of a 16-electromagnetic valve, a valve of a main passage of a 17-electromagnetic valve, a piston component of an 18-piston, a 19-active deflation passage, a spring of a right valve of a 20-electromagnetic valve, a 21-filter, a 22-pilot-air passage, a 23-main passage, an outlet (A), an electromagnetic valve exhaust passage (B), an inlet (C), an inlet (P) and an exhaust port (R).

Detailed Description

The invention is described in further detail below with reference to specific embodiments and figures.

The emergency energy system is praised as the last rescue straw of the airplane, and can be rapidly unfolded to work when the main hydraulic energy system and the main power supply system of the airplane fail, so as to provide emergency energy for the airplane. The combined valve is an important component of an emergency system capable of ensuring that the aircraft keeps operability when the main power and the auxiliary power are lost, an EPS start-stop control component on the aircraft can send 28V direct current to an emergency energy system controller through an automatic circuit, the combined valve is started after receiving an electric signal, the pressure is output, a fuel tank is pushed, the fuel is catalytically decomposed into high-temperature high-pressure gas through a decomposition chamber to push a turbine to work, the power of the output shaft is output, and the emergency energy system starts to work.

The embodiment of the invention provides a combined valve capable of actively deflating, which is used for the emergency energy system, can discharge leakage gas when the combined valve leaks in a power-off state, solves the problem of failure reporting of external field leakage, and does not change the working parameters of the combined valve in an electrified state, so that the normal working of a product at the rear end of a pressure reducing valve is not influenced.

The embodiment of the invention provides a combined valve capable of actively deflating, which comprises an electromagnetic valve, a pressure reducing valve, a one-way valve and a safety valve, as shown in figure 1.

The electromagnetic valve comprises an electromagnetic valve right valve 1, an electromagnetic valve rod assembly 2, an electromagnetic valve left valve 3, an armature 4, a coil 5 and an electromagnetic valve right valve spring 20, wherein the electromagnetic valve rod assembly 2 is connected with the electromagnetic valve right valve 1 and the electromagnetic valve left valve 3 through a straight rod thread, the electromagnetic valve right valve 1 and the electromagnetic valve left valve 3 are coaxially pressed on respective valve seats, the electromagnetic valve right valve rod assembly and the electromagnetic valve left valve rod assembly play a role in sealing a pilot air channel 22 and an electromagnetic valve exhaust channel B, and the electromagnetic valve left valve 3 is connected to a valve rod through threads and is in clearance fit with the armature 4. A sealing ring is arranged in the solenoid valve rod assembly 2 to seal the pilot air channel 22 and the exhaust port R. The sealing ring is arranged on the contact surface of the solenoid valve rod assembly 2 and the shell 8, the solenoid valve left valve 3, the solenoid valve right valve 1 and the solenoid valve rod assembly 2 are arranged on the same horizontal plane, and the central line is overlapped with the central lines of the solenoid valve coil 5 and the armature 4. The left solenoid valve 3 and the right solenoid valve 1 are connected through the solenoid valve rod assembly 2 and the sealing ring, one side can be closed and the other side can be opened, and meanwhile, the middle cavity is sealed, so that working medium is not leaked.

When the electromagnetic valve is electrified, under the electromagnetic force action of the armature 4, the left valve 3 of the electromagnetic valve moves along the axis towards the direction close to the exhaust passage B of the electromagnetic valve, the right valve 1 of the electromagnetic valve moves along the axis towards the direction far away from the exhaust passage B of the electromagnetic valve, the active air release passage 19 and the exhaust passage B of the electromagnetic valve are isolated under the action of the left valve 3 of the electromagnetic valve, meanwhile, the first air release passage 22 and the exhaust passage B of the electromagnetic valve are isolated under the sealing action of the valve rod assembly 2 of the electromagnetic valve, even if the active air release passage 19 is communicated with the first air release passage 22 at the moment, the active air release passage 19 does not influence the normal operation of the combined valve when the electromagnetic valve is electrified because the diameters of the active air release passage 19 and the main passage 23 are different in order of magnitude, as shown in figure 3;

when the power is off, the armature 4 loses the electromagnetic force effect, the electromagnetic valve rod assembly 2 resets under the action of the electromagnetic valve right valve spring 20, the electromagnetic valve left valve 3 moves along the axis in the direction away from the electromagnetic valve exhaust passage B, the active air release passage 19 is communicated with the atmosphere through the electromagnetic valve exhaust passage B, and therefore air leaked by the electromagnetic valve main passage valve can be discharged outwards through the active air release passage 19 and the electromagnetic valve exhaust passage B. The right valve 1 of the solenoid valve moves along the axis in the direction of approaching the exhaust passage B of the solenoid valve, presses against the valve seat of the housing, and the active air release passage 19 is isolated from the air release passage 22 by the left valve 3 of the solenoid valve. The solenoid valve main passage shutter 17 is reset by the spring force of the solenoid valve main passage spring 16 to close the main passage, forming a long-time high-pressure seal, as shown in fig. 2.

The rear end of the electromagnetic valve is directly connected with a pressure reducing valve, the pressure reducing valve is provided with a main passage and a pressure sensing passage 10 of the pressure reducing valve, the main passage of the pressure reducing valve can reduce high-pressure gas from an upstream electromagnetic valve to required pressure through a bellows spring assembly 7, and meanwhile, a feedback passage can adjust the opening degree of the pressure reducing valve in real time according to the change of the pressure at the rear end, and the output pressure at the rear end is adjusted.

The pressure reducing valve mainly comprises a pressure reducing valve cavity 6, a corrugated pipe spring assembly 7, a valve sleeve assembly 9, a pressure reducing valve pressure sensing passage 10 and a pressure reducing valve 15, wherein the corrugated pipe spring assembly 7 is assembled in the pressure reducing valve cavity 6 in a coaxial clearance mode, the pressure reducing valve 15 is connected to the corrugated pipe spring assembly 7 through a valve rod in a threaded mode, a through hole is formed in the valve sleeve assembly 9 and used for passing through high-pressure media, and the pressure reducing valve 15 is assembled in the coaxial clearance mode. Two sealing rings are arranged between the valve sleeve assembly 9 and the shell 8.

When the pressure-reducing valve is electrified, the pressure-reducing valve cavity 6 senses fluctuation of outlet pressure in real time through the pressure-sensing passage 10 of the pressure-reducing valve, along with the increase of the outlet pressure of the pressure-reducing valve, the bellows spring assembly 7 moves towards a direction away from the valve sleeve assembly 9 under the action of pressure difference at two ends, the opening degree of the valve 15 of the pressure-reducing valve is gradually reduced, the outlet pressure of the pressure-reducing valve is controlled to be a proper value, when the pressure-reducing pressure reaches (2.9-3.1) MPa, the valve 15 of the pressure-reducing valve is tightly pressed on the valve sleeve assembly 9, and the outlet of the pressure-reducing valve is in a closed state so as to meet the requirement of certain working pressure of a fuel tank at the rear end, as shown in figure 3.

When the power is off, the pressure reducing valve is not pressurized at the rear end, the bellows spring assembly 7 moves towards the direction approaching the valve sleeve assembly 9 under the action of the pressure difference at the two ends, and the valve 15 of the pressure reducing valve is adjusted to be in an open state, as shown in fig. 2.

The pressure reducing valve is connected with the one-way valve, the one-way valve is communicated with the outlet, the one-way valve only allows media to pass through in one direction, and the back-end fuel backflow corrosion combined valve can be prevented through reverse sealing of the one-way valve 11 and the one-way valve spring 12.

When the power is on, the check valve door 11 moves coaxially towards the direction of the outlet A against the acting force (0.7N) of the check valve spring 12 under the action of pressure difference, and opens the passage, and the medium is led to the rear-end fuel tank from the outlet A on the shell 8.

When the power is off, the check valve 11 is tightly pressed on the valve seat of the shell 8 under the action of the check valve spring 12, so that the check valve is closed to play a role in reverse sealing, and the fuel medium at the rear end is prevented from entering the combined valve to corrode components.

A safety valve is arranged between the one-way valve and the outlet, the safety valve plays a role in overpressure protection, and when the output pressure of the pressure reducing valve is overlarge, the safety valve is opened in an emergency mode, so that the normal operation of the system can be prevented from being damaged due to overlarge pressure.

The relief valve mainly includes a relief valve shutter 13 and a relief valve spring 14. When the outlet pressure of the pressure reducing valve exceeds the standard, the safety valve door 13 is opened against the acting force of the safety valve spring 14 to play a role in emergency pressure relief, and the pressure of the rear-end system is protected from exceeding the standard, so that the safety of an airplane and personnel is protected.

As shown in fig. 4 and 5, for the active air release passage 19, the horizontal distance between the active air release passage 19 and the center line of the solenoid valve mounting hole is 6-8mm, and the center line of the active air release passage 19 and the center line of the solenoid valve mounting hole are on the same plane and are 15-25 degrees.

Illustratively, the active bleed passages 19 may be perforated in the housing 8 by means of an electric spark, the active bleed passages 19 having a length of 10-12mm and the active bleed passages 19 having a diameter of 0.2-0.6mm.

When the power is off, the main passage valve 15 of the electromagnetic valve is sealed at high pressure (20 MPa-24 MPa) for a long time (1 month), the leakage index is required to be not more than 1 multiplied by 10 < -3 > L/h, the leakage of the sealing part is easy to exceed the standard in actual conditions because the prior conical sealing line contact sealing cannot be completely performed, after the active air release passage 19 is increased, the rear end of the pressure reducing valve is preferably discharged from the exhaust passage of the electromagnetic valve due to the resistance action of the one-way valve spring 12 when the power is off, so that the rear end of the pressure reducing valve cannot accumulate the pressure of the medium, the rear end system of the pressure reducing valve can be protected when the main passage valve 17 of the electromagnetic valve is in sealing failure, and the false start of a fuel tank is avoided.

When the electromagnetic valve is electrified, the right valve 1 of the electromagnetic valve is opened, the left valve 3 of the electromagnetic valve is closed, working medium firstly enters the pilot gas channel, under the action of pressure difference, the piston assembly 18 overcomes the spring force of the main passage spring 16 of the electromagnetic valve and moves towards the direction of the main passage spring 16, the main passage is opened, meanwhile, the active gas release passage 19 has an order of magnitude difference with the main passage (5 mm) due to the smaller diameter, and therefore, the pressure of the active gas release passage 19 is small when being started, and the response time of the electromagnetic valve is hardly influenced.

Because the diameters of the passages in the shell 8 including the active air release passage 19 are smaller, if foreign matters exist in the air source, the passages are easy to be blocked, and then the combined valve is not opened and is blocked, in order to avoid the situation, a high-density multi-layer filter 21 is added at the inlet of the combined valve shell 8, and the mesh diameter is 40 mu m, so that the pollution resistance can be improved.

For example, the combined valve housing 8 is made of titanium alloy TC4 material, can bear 28MPa pressure at maximum, is lighter in weight, has good high-low temperature resistance, mechanical load resistance and corrosion resistance, and has a compact overall structure.

The foregoing has outlined rather broadly the more detailed description of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present invention may be better understood. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. In addition, the invention is not fully described in the conventional technology.

Claims (9)

1. The utility model provides a but combination valve of initiative gassing, its characterized in that includes the casing and is located the valve body of casing, and the valve body includes the solenoid valve, and the solenoid valve rear end is directly connected with the relief valve, and the relief valve is connected with the check valve, and the check valve intercommunication export is equipped with the relief valve between check valve and the export, is equipped with on the casing and makes the initiative gassing passageway (19) of leaking gas outwards discharge, and initiative gassing passageway (19) are located between solenoid valve exhaust passageway B and the relief valve entry C.

2. A combination valve according to claim 1, wherein the active bleed passage (19) is located at a horizontal distance of 6-8mm from the centre line of the solenoid valve mounting hole, the centre line of the active bleed passage (19) being in the same plane as the centre line of the solenoid valve mounting hole and being 15-25 degrees.

3. A combination valve according to claim 1, characterised in that the casing (8) is perforated by means of an electric spark to form an active bleed passage (19), the active bleed passage (19) having a length of 10-12mm.

4. A combination valve according to claim 1, wherein the active bleed passage (19) has a diameter of 0.2-0.6mm.

5. The combination valve of claim 1 wherein the inlet port in the combination valve housing is provided with a high density multilayer filter.

6. The combination valve according to claim 1, wherein the solenoid valve is provided with a main passage, a pilot gas passage, an exhaust passage and an active gas release passage,

the active air release passage in the electromagnetic valve is connected with the air release passage and the rear end of the electromagnetic valve, the main passage is a high-pressure air passage, air is introduced into the main passage, the right valve of the electromagnetic valve opens the pilot air passage under the action of electromagnetic force, so that the air pressure in the inner cavity of the main passage of the electromagnetic valve is reduced, the valve of the main passage of the electromagnetic valve is opened under the action of air pressure difference, and the main passage is opened; the electromagnetic valve exhaust passage discharges the gas of the first gas guiding passage when the power is off.

7. The combination valve of claim 1, wherein the solenoid valve comprises a right solenoid valve flapper, a solenoid valve flapper lever assembly, a left solenoid valve flapper, the left solenoid valve flapper being connected to the right solenoid valve flapper by the solenoid valve flapper lever assembly and a seal ring.

8. The combination valve of claim 7, wherein the gasket is located on the solenoid valve spool and housing interface, the solenoid valve further comprising an armature, a coil, the solenoid valve left spool, the solenoid valve right spool, and the solenoid valve spool assembly are mounted on the same horizontal plane with a centerline coincident with the solenoid valve coil, armature centerline.

9. The combination valve according to claim 1, wherein the pressure reducing valve is provided with a main passage and a pressure sensing passage of the pressure reducing valve, the main passage of the pressure reducing valve reduces the high-pressure gas from the upstream electromagnetic valve to a required pressure through the pressure sensing throttling assembly, and the pressure sensing passage of the pressure reducing valve adjusts the opening degree of the pressure reducing valve in real time according to the change of the pressure at the rear end to adjust the output pressure at the rear end.