High precision pilot pressure reducer

Abstract

The present invention discloses a high-precision pilot pressure reducer, which comprises a pilot valve and a main valve connected in parallel. The pilot valve is a forward pressure reducer, a sensitive back-pressure chamber is provided on the back-pressure side of the main valve, the pressure airflow at the pilot valve outlet enters the sensitive back-pressure chamber, and the sensitive back-pressure chamber is followed by a main valve movable mechanism, including a main valve valve assembly and a main valve spring. The main valve valve assembly comprises a sensitive piston and a high-pressure sealing ring, a back-pressure plate moves up and down along a main valve seat, one side of the sensitive piston is a sensitive back-pressure chamber, and the other side is an outlet chamber of the main valve, the high-pressure sealing ring blocks and seals the connecting air path between the pilot valve inlet and the outlet chamber, a vent is provided on the sensitive piston, and the vent connects the sensitive back-pressure chamber and the outlet chamber of the main valve. The high-precision pilot pressure reducer of the present invention has small output pressure deviation, high precision, a pilot type, and a compact design, and is suitable for occasions where the inlet-outlet pressure ratio is greater than or equal to 40.

Description

Technical Field

[0001] The present invention relates to the technical field of inventions, and in particular to a pilot pressure reducer. Background Art

[0002] At present, the pressure reducers on the market are mainly single-stage reverse non-unloading pressure reducing valves. This valve has the advantages of high reliability, long life, low cost, etc., which can meet the general use requirements; in the fields of aviation and aerospace, the pressure reducers have more precision and miniaturization requirements. In recent years, the high-precision pressure reducers developed in the domestic aerospace field are mainly two-stage pressure reducers, including reverse-reverse series, forward-reverse series, and forward-forward series. Parallel pressure reducers are relatively rare, and pilot pressure reducers are a type of parallel pressure reducers. Its accuracy is mainly controlled by the accuracy of the pilot valve, hence the name. Several commonly used pilot pressure reducers in industry are 1TY25-3 high-pressure pressure reducers, Y43H piston pressure reducers and YZZH piston pressure reducers. The 1TY25-3 high-pressure pressure reducer is the common feature of the above pilot pressure reducers is that the working flow is large, but when the inlet pressure is greater than 20MPa or the inlet has a large pressure drop, the above three pilot pressure reducers cannot provide a high-precision output pressure. The main reason is that the above three types of valves mainly consider large flow requirements, but configuring a pilot valve with the same characteristic on the reverse main valve with an upward tilt characteristic will superimpose the deviations of the pilot valve and the main valve.

[0003] Prior art 2019100252630 discloses a two-stage pilot pressure reducer, which is characterized in that the product is integrated with three pressure reducers, namely, the first-stage pressure reducer, the second-stage main valve, and the pilot valve. Looking at the parallel structure of the second-stage main valve and the pilot valve alone, the adjustment accuracy of this structure is low when the inlet pressure changes greatly; therefore, the design and the pressure reducer initially reduce the pressure of the high-pressure gas and then pass it to the pilot valve.

[0004] After the first stage is initially decompressed, the first stage outlet pressure flows into the pilot valve and the second stage main valve. Compared with this patent, the butterfly valve used in this invention has a large rigidity, which leads to a decrease in the accuracy of the pilot valve; the pressure in the pilot valve sensitive chamber is the outlet pressure of the second stage main valve, and this pressure negatively feedback controls the opening of the pilot valve. Therefore, the pilot valve is a controlled valve, and its autonomous pressure regulating ability is relatively poor. Its structure is similar to the Y43H series piston pressure reducing valve widely used in industry.

[0005] In the prior art, 201720952233.0 discloses a high-precision absolute pressure reducer, which is a two-stage series pressure reducer. Compared with the parallel pressure reducer described in this patent, it is more suitable for small and medium flow rates. This is because when designing a large flow rate, the required valve seat aperture and sensitive area are large, and the corresponding main spring load is also large, which not only brings great difficulties to the spring design, but also affects the miniaturization design.

[0006] In short, with the increasingly stringent requirements for the outlet pressure accuracy of the pressure reducer, it is very difficult to ensure that the volume of all products in the system is as small as possible while ensuring that the output pressure is highly accurate and stable and reliable. When the pneumatic pressure reducing valve is used for large flow and high outlet pressure, the traditional direct-acting pressure reducer greatly improves the accuracy and reduces the volume of the pressure reducer. Therefore, a new type of pilot parallel pressure reducer is proposed to meet the high-precision regulation requirements under this working condition. Summary of the invention

[0007] The technical problem solved by the present invention is to provide a high-precision pilot pressure reducer, which can meet the requirements of high, stable and reliable outlet pressure accuracy while keeping the product volume as small as possible.

[0008] The technical solution adopted by the present invention is a high-precision pilot pressure reducer, including a pilot valve and a main valve connected in parallel. The pilot valve is a forward pressure reducer, including a pilot valve main spring, a double valve rod, a pilot valve core, and a pilot valve auxiliary spring installed in sequence in a shell. A sensitive back-pressure chamber is provided on the back-pressure side of the main valve. The pressure airflow at the pilot valve outlet enters the sensitive back-pressure chamber. The main valve movable mechanism behind the sensitive back-pressure chamber includes a main valve valve assembly and a main valve spring. The main valve valve assembly includes a sensitive piston and a high-pressure sealing ring. The back-pressure plate moves up and down along the main valve seat. One side of the sensitive piston is a sensitive back-pressure chamber, and the other side is an outlet chamber of the main valve. The high-pressure sealing ring blocks and seals the connecting air path between the pilot valve inlet and the outlet chamber. A vent is provided on the sensitive piston, and the vent connects the sensitive back-pressure chamber and the outlet chamber of the main valve. The main valve spring pushes the sensitive piston toward the sensitive back-pressure chamber.

[0009] A variable hole screw is installed on the sensitive piston, and a through hole is provided in the center of the variable hole screw as a vent hole.

[0010] The width of the sensitive piston near the main valve seat is increased, and two sealing rings are arranged on the outer circumference.

[0011] The high-pressure sealing ring and the sensitive piston are connected through a valve rod, and the main valve spring is sleeved outside the valve rod.

[0012] The beneficial effects of the present invention are that the pilot valve adopts a positive non-unloading structure, in which no valve stem passes through the valve core, so the valve seat diameter can be fully miniaturized. Under the condition that the sensitive area remains unchanged, the valve diameter is reduced, the sensitive diameter ratio of the pressure reducer is increased, the outlet pressure accuracy of the pilot valve is improved, and the miniaturization design of the pilot valve is realized; the main valve adopts a reverse unloading structure, which avoids the influence of the inlet pressure step on the outlet pressure, and moves the main valve return spring down to the sensitive chamber, so as to fully realize the compact design; a variable hole screw is provided on the main valve piston, and the screw hole size is serialized so that the pilot valve can adapt to the outlet pressure accuracy under different flow rates; the pilot valve and the main valve structure are a parallel combination of a forward and a reverse pressure reducer, which fully utilizes the characteristics of the two pressure reducers, offsets the errors caused by opposite characteristics, and can obtain higher precision pressure characteristics through parameter design; BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the present invention.

[0014] Figure 2 This is a partial structural diagram of the pilot valve.

[0015] Markings in the figure are: 1-pilot valve inlet, 2-pilot valve inlet, 3-main valve valve assembly, 31-sealing ring, 4-main valve spring, 5-pilot valve outlet, 6-diaphragm, 7-variable hole screw, 8-pilot valve outlet, 9-pilot valve auxiliary spring, 10-pilot valve core, 11-double valve rod, 12-pilot valve main spring, 21-plunger, 22-cylinder, 23-diaphragm, 24-air pressure chamber. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings.

[0017] Figure 1 The figure shows the structural principle diagram of the pilot-operated pressure reducer of the present invention. An integrated design can be adopted between the pilot valve and the main valve, that is, an internally connected form, or a parallel form in which two pressure reducing valves are connected by external pipelines.

[0018] The pilot valve is a new type of positive pressure reducer. The internal active mechanism of the pressure reducer is composed of a pilot valve auxiliary spring 9, a pilot valve core 10, a double valve rod 11, and a pilot valve main spring 12. After the high-pressure gas passes through the inlet, it enters the pilot valve inlet 1, flows into the narrow gap formed by the pilot valve core 10 and the valve seat, and then is reduced to the outlet pressure. The size of the outlet pressure can be determined by adjusting the spring preload, such as Figure 2As shown, the sensitive surface of the pilot valve adopts a non-metallic diaphragm 23, and the back pressure side of the diaphragm adopts a plunger 21 and a cylinder 22 with a small gap. The non-metallic diaphragm replaces the rubber ring in the traditional pressure reducer to play a sealing role. At the same time, when the pilot valve starts to work, the non-metallic diaphragm can use the protection of the plunger and the cylinder to withstand higher pressure under a small displacement, thereby achieving reliable sealing and no friction caused by non-metallic active seals during operation.

[0019] The pressure gas at the pilot valve outlet flows into the sensitive back pressure chamber, and then flows into the main valve outlet chamber through the vent hole in the middle of the variable hole screw 7. The size of the vent hole determines the pilot valve flow rate, which cannot be accurately obtained through fluid calculation and is generally obtained through analysis and simulation of fluid.

[0020] In order to obtain different flow rates, the variable hole screw can be a series of screws, the central vent holes of which have different apertures, and different types of variable hole screws can be replaced according to the flow requirements of the pressure reducer.

[0021] The main valve in the present application is a unloading type reverse pressure reducer, and its movable mechanism is composed of a main valve valve combination 3 and a main valve spring 4. The design feature of the pressure reducer is that the inlet pressure is throttled and reduced through the throttling gap, and a high-pressure sealing ring is arranged between the valve rod and the shell, and its function is to isolate the upper end face of the main valve valve combination 3 from the high-pressure gas, that is, to isolate it from the pilot valve inlet 1, and introduce the outlet low-pressure gas. In this way, the high-pressure gas has a small force on the main valve valve combination 3, that is, the entire movable mechanism is little affected by the high-pressure gas. Therefore, when the high-pressure gas changes, the outlet pressure changes very little, and the accuracy is high.

[0022] During the operation of the pilot valve, when the outlet pressure of the pilot valve pushes the valve assembly 3 of the main valve upward, the gas in the high-pressure chamber of the main valve is reduced to P2 pressure at the valve, and then output from the main valve outlet 5 at a certain specified flow rate. When the outlet pressure of the main valve drops for some reason, the pressure difference between the upper and lower parts of the sensitive piston 31 is increased, destroying the main valve force balancing mechanism, thereby moving the main valve valve assembly 3 upward, increasing the main valve opening, increasing the mass flow rate, and correspondingly increasing the outlet pressure of the valve. Through the high-precision design of the pilot valve, the accuracy of the outlet pressure of the main valve is improved, and the outlet pressure of the main valve has the same characteristics as the gas spring pressure reducing valve. Since the air pressure chamber of the traditional gas spring pressure reducer is an absolute pressure chamber, it is greatly affected by temperature. When the temperature changes, the pressure of the sensitive back pressure chamber changes accordingly, and the outlet pressure balanced with it also changes. However, the pressure reducer of the present application has a non-enclosed chamber, and its pressure in the chamber is completely controlled by the pilot valve. The pilot valve is a gauge pressure pressure reducer, which is basically not affected by temperature changes and has better environmental adaptability.

[0023] Since the pilot valve is a positive non-unloading pressure reducer, based on the design principle of the pressure reducer, the static characteristics of the outlet pressure of all positive pressure reducers are: under the premise of a fixed volume flow rate, when the inlet pressure changes from high to low, the outlet pressure will also change from high to low;

[0024] The main valve is a reverse pressure reducer. Based on the design principle of the pressure reducer, the static characteristics of the outlet pressure of all classic reverse pressure reducers are: under the premise of a fixed volume flow rate, when the inlet pressure changes from high to low, the outlet pressure changes from low to high;

[0025] For example, when the inlet pressure is 40-30MPa, the pilot valve outlet is 3-2.8MPa;

[0026] When the inlet pressure is 40-30MPa, the outlet pressure of the main valve should be 2.6-2.7MPa if it is not affected by the pilot valve;

[0027] When the outlet pressure change of the pilot valve is taken into account, the outlet pressure of the pilot valve decreases, which will directly lead to the breaking of the force balance of the sensitive piston and a decrease in the outlet pressure. Therefore, the change of the main valve is no longer 2.6-2.7MPa. By listing the force balance formula and static characteristic calculation formula of the main valve and pilot valve, we can get how to design parameters to minimize the deviation of the outlet pressure.

[0028] Therefore, the unloading design of the main valve makes the main valve less affected by changes in the inlet pressure. Through parameter design, the pilot valve and the main valve structure are a parallel combination of forward and reverse pressure reducers, which offset the errors caused by opposite characteristics and also improve the accuracy of the pressure reducing valve.

[0029] In summary, the technical solution of the present application uses a micro-flow forward pressure reducing valve with a large sensitive diameter ratio as a pilot valve to provide a high-precision pilot valve pressure as the back pressure load of the sensitive area of ​​the main valve; a reverse unloading medium and large diameter pressure reducing valve is used as the main valve, which is equipped with a large sensitive area to increase its sensitive pressure ratio, thereby meeting the requirements of medium and large flow rates, medium and high pressures with higher precision, and the outlet pressure has high accuracy; there is no non-metallic sealing ring in the active mechanism of the pilot valve, the operation is more stable and reliable, there is no accessory friction, and the pilot valve has high accuracy; under large flow conditions, a maximum pressure reduction ratio of 40 times can be achieved, and the outlet pressure accuracy can reach ±2%, which can achieve high precision and realize the miniaturization of medium and large flow pressure reducing valves.

Claims

1. High-precision pilot pressure reducer, including a pilot valve and a main valve connected in parallel, characterized by: The pilot valve is a forward pressure reducer, comprising a pilot valve main spring (12), a double valve rod (11), a pilot valve core (10), and a pilot valve auxiliary spring (9) which are sequentially installed in a housing. A sensitive back pressure chamber is provided on the back pressure side of the main valve. The pressure airflow at the pilot valve outlet enters the sensitive back pressure chamber. The main valve movable mechanism behind the sensitive back pressure chamber comprises a main valve valve assembly (3) and a main valve spring (4). The main valve valve assembly (3) comprises a sensitive piston and a high pressure sealing ring. The back pressure plate moves up and down along the main valve seat. One side of the sensitive piston is the sensitive back pressure chamber, and the other side is the outlet chamber of the main valve. The high pressure sealing ring blocks and seals the connecting air path between the pilot valve inlet (1) and the outlet chamber. A vent hole is provided on the sensitive piston. The vent hole connects the sensitive back pressure chamber and the outlet chamber of the main valve. The main valve spring (4) pushes the sensitive piston toward the sensitive back pressure chamber. A variable hole screw (7) is installed on the sensitive piston, and a through hole is provided at the center of the variable hole screw (7) as a vent hole; The width of the sensitive piston near the main valve seat is increased, and two sealing rings (31) are provided on the outer circumference; The high pressure sealing ring and the sensitive piston are connected via a valve rod, and the main valve spring (4) is sleeved outside the valve rod.

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