A constant pressure reducing valve

Abstract

The present invention discloses a constant pressure reducing valve, comprising a valve body, a first end provided with a primary low pressure chamber and a primary transition chamber, a second end provided with a secondary low pressure chamber and a secondary transition chamber, an air inlet and an air outlet are opened on the side wall of the valve body, the air inlet, the primary transition chamber, the primary low pressure chamber, the secondary transition chamber, the secondary low pressure chamber and the air outlet are connected in sequence; a primary pressure regulating assembly is arranged at the connection point between the primary transition chamber and the primary low pressure chamber; a secondary pressure regulating assembly is arranged at the connection point between the secondary transition chamber and the secondary low pressure chamber; a primary valve cover is connected to the first end, a primary pressure sensitive element is pressed between the primary valve cover and the first end, and a primary valve cover elastic element is arranged in the primary valve cover cavity; a secondary valve cover is connected to the first end, a secondary pressure sensitive element is pressed between the secondary valve cover and the first end, and a secondary valve cover elastic element is arranged in the secondary valve cover cavity; a handle is fixedly connected to one end of the secondary top screw extending out of the secondary valve cover. The output pressure and flow of the constant pressure reducing valve are stable, and it is easy to close and open.

Description

Technical Field

[0001] The invention relates to the technical field of pressure reducing valves, in particular to a constant-pressure pressure reducing valve. Background Art

[0002] Pressure reducing valves are widely used in laboratories, electronic semiconductors, biomedicine, petroleum, petrochemicals, gas, electricity, chemicals, aerospace, solar energy and other fields. They are valves that make the medium pressure meet the pressure requirements of the production process. At present, there are many types of constant pressure pressure reducing valves. The most common one is the single-stage preset type. When not in use, the pressure reducing valve is in an open state for a long time and cannot be closed because there is no pressure difference between the high and low pressure chambers of the pressure reducing valve. Since the pressure of the gas source (high pressure chamber) will continue to drop during use, in order to achieve a balanced state, the low pressure chamber pressure will rise as the gas source pressure drops, resulting in unstable output pressure. Changes in the gas source pressure and the low pressure chamber pressure will cause changes in the output flow rate. In addition, there are problems such as inability to close, unstable output pressure, and unstable output flow rate. Therefore, it is necessary to provide a new technical solution to solve the above problems. Summary of the invention

[0003] The purpose of the present invention is to provide a constant pressure reducing valve to solve the problems existing in the above-mentioned prior art, so that the output pressure and output flow of the constant pressure reducing valve are stable and it is convenient to close and open the constant pressure reducing valve.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a constant-pressure pressure-reducing valve, comprising a valve body, a primary valve cover, a secondary valve cover and a handle, the two ends of the valve body are respectively a first end and a second end, the first end is provided with a primary low-pressure chamber and a primary transition chamber in sequence from the outside to the inside, the second end is provided with a secondary low-pressure chamber and a secondary transition chamber in sequence from the outside to the inside, an air inlet and an air outlet are provided on the side wall of the valve body, the air inlet, the primary transition chamber, the primary low-pressure chamber, the secondary transition chamber, the secondary low-pressure chamber and the air outlet are connected in sequence; a primary pressure-regulating assembly is provided at the connection between the primary transition chamber and the primary low-pressure chamber, and the compression amount of the primary elastic element is adjusted by the primary top screw, so that the primary pressure-regulating assembly can be connected or separated from the primary transition chamber and the primary low-pressure chamber; a secondary pressure-regulating assembly is provided at the connection between the secondary transition chamber and the secondary low-pressure chamber, and the compression amount of the secondary elastic element is adjusted by the secondary top screw, so that the secondary pressure-regulating assembly can be connected or separated from the secondary transition chamber and the secondary low-pressure chamber. cavity; the first-level valve cover is fixedly connected to the first end, and a first-level pressure-sensitive element is provided in the first-level valve cover and the first-level low-pressure cavity, the first-level pressure-sensitive element closes the opening of the first-level low-pressure cavity, and a first-level valve cover elastic element is provided in the cavity of the first-level valve cover, one end of the first-level elastic element can contact the first-level pressure-sensitive element, and the other end of the first-level elastic element can contact with a first-level top screw threadedly connected to the first-level valve cover; the second-level valve cover is fixedly connected to the first end, and a second-level pressure-sensitive element is provided in the second-level valve cover and the second-level low-pressure cavity, the second-level pressure-sensitive element closes the opening of the second-level low-pressure cavity, and a second-level valve cover elastic element is provided in the cavity of the second-level valve cover, one end of the second-level elastic element can contact with the second-level pressure-sensitive element, and the other end of the second-level elastic element can contact with a second-level top screw threadedly connected to the second-level valve cover; the handle is fixedly connected to one end of the second-level top screw extending out of the second-level valve cover.

[0006] Preferably, the first-level pressure regulating assembly includes a first-level valve seat assembly, a first-level valve needle and a first-level supporting elastic element, the first-level valve seat assembly is fixedly arranged at the connection point between the first-level transition chamber and the first-level low-pressure chamber, the first-level valve needle passes through the first-level valve seat assembly, and one end of the first-level valve needle can contact the first pressure sensitive element, and the first-level supporting elastic element is arranged between the other end of the first-level valve needle and the bottom surface of the first-level transition chamber; the second-level pressure regulating assembly includes a second-level valve seat assembly, a second-level valve needle and a second-level supporting elastic element, the second-level valve seat assembly is fixedly arranged at the connection point between the second-level transition chamber and the second-level low-pressure chamber, the second-level valve needle passes through the second-level valve seat assembly, and one end of the second-level valve needle can contact the second pressure sensitive element, and the second-level supporting elastic element is arranged between the other end of the second-level valve needle and the bottom surface of the first-level transition chamber.

[0007] Preferably, it also includes a limit assembly, which is arranged on the secondary valve cover and is used to limit the rotation angle of the handle and adjust the compression amount of the secondary elastic element so that the secondary pressure regulating assembly connects or separates the secondary transition chamber and the secondary low-pressure chamber.

[0008] Preferably, a first-level elastic element is provided with a first-level pressure block at one end for contacting the first-level top screw, and two ends of the first-level pressure block are respectively in contact with the first-level top screw and the first-level elastic element; a second-level elastic element is provided with a second-level pressure block at one end for contacting the second-level top screw, and two ends of the second-level pressure block are respectively in contact with the second-level top screw and the second-level elastic element.

[0009] Preferably, the primary pressure sensitive element and the secondary pressure sensitive element are diaphragms or pistons.

[0010] Preferably, the limit assembly includes a sleeve nut, the sleeve nut is threadedly connected to the outside of the secondary valve cover, the handle is movably sleeved outside the sleeve nut, an opening limit portion and a closing limit portion are provided at one end of the sleeve nut close to the handle, a handle limit portion is provided on the inner wall of one end of the handle close to the sleeve nut, and the handle limit portion moves between the opening limit portion and the closing limit portion.

[0011] Preferably, the handle limiting portion, the opening limiting portion and the closing limiting portion are all limiting screws.

[0012] Preferably, the first-level valve seat assembly includes a first-level valve seat fixedly arranged on the valve body, a first-level sealing gasket is also arranged between the first-level valve seat and the valve body, and a first-level air vent hole for passing the first-level valve needle is formed on the first-level valve seat and the first-level sealing gasket. One end of the first-level valve needle is located in the first-level transition chamber to form a first-level sealing head, and the first-level sealing head can open or close the first-level air vent hole.

[0013] Preferably, the secondary valve seat assembly includes a secondary valve seat fixedly arranged on the valve body, a secondary sealing gasket is also arranged between the secondary valve seat and the valve body, and a secondary air vent hole for passing the secondary valve needle is formed on the secondary valve seat and the secondary sealing gasket. One end of the secondary valve needle is located in the secondary transition chamber to form a secondary sealing head, and the secondary sealing head can open or close the secondary air vent hole.

[0014] Preferably, the primary valve cover and the secondary valve cover are both threadedly connected to the valve body.

[0015] Compared with the prior art, the present invention has achieved the following technical effects:

[0016] The constant pressure reducing valve provided by the present invention realizes double pressure reduction from the air inlet to the air outlet, effectively reducing the influence of the pressure change of the air inlet on the pressure change of the air outlet, and making the output pressure and output flow of the constant pressure reducing valve stable. In addition, the handle is fixedly connected to one end of the secondary top screw extending out of the secondary valve cover, and by rotating the handle, the length of the secondary top screw extending into the secondary valve cover can be adjusted, thereby adjusting the compression amount of the secondary elastic element, which is convenient for closing and opening the constant pressure reducing valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic diagram of the structure of the constant pressure reducing valve provided by the present invention;

[0019] In the figure: 1-first-level top screw; 2-first-level valve cover; 3-first-level pressure block; 4-first-level elastic element; 5-first-level pressure sensitive element; 6-first-level valve seat; 7-first-level sealing gasket; 8-first-level valve needle; 9-first-level supporting elastic element; 10-second-level supporting elastic element; 11-second-level valve needle; 12-second-level sealing gasket; 13-second-level valve seat; 14-second-level valve cover; 15-second-level pressure sensitive element; 16-second-level elastic element; 17-sleeve nut; 18-second-level pressure block; 19-opening limit part; 20-secondary top screw; 21-handle; 22-valve body; 23-handle limit part; 24-air inlet; 25-first-level low-pressure chamber; 26-second-level low-pressure chamber; 27-air outlet. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The purpose of the present invention is to provide a constant pressure reducing valve to solve the problems existing in the above-mentioned prior art, so that the output pressure and output flow of the constant pressure reducing valve are stable and it is convenient to close and open the constant pressure reducing valve.

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1 As shown, the present invention provides a constant pressure reducing valve. In a specific embodiment of the present invention, the constant pressure reducing valve comprises a valve body 22, a primary valve cover 2, a secondary valve cover 14 and a handle 21. The two ends of the valve body 22 are respectively a first end and a second end. The first end is provided with a primary low pressure chamber 25 and a primary transition chamber in sequence from outside to inside. The second end is provided with a secondary low pressure chamber 26 and a secondary transition chamber in sequence from outside to inside. An air inlet 24 and an air outlet 27 are provided on the side wall of the valve body 22. The air inlet 24, the primary transition chamber, the primary low pressure chamber 25 and the primary transition chamber 26 are provided on the side wall of the valve body 22. 5. The secondary transition chamber, the secondary low-pressure chamber 26 and the air outlet 27 are connected in sequence; a primary pressure regulating assembly is provided at the connection between the primary transition chamber and the primary low-pressure chamber 25, and the compression amount of the primary elastic element 4 is adjusted by the primary top screw 1, so that the primary pressure regulating assembly can be connected or separated from the primary transition chamber and the primary low-pressure chamber 25; a secondary pressure regulating assembly is provided at the connection between the secondary transition chamber and the secondary low-pressure chamber 26, and the compression amount of the secondary elastic element 16 is adjusted by the secondary top screw 20, so that the secondary pressure regulating assembly can be connected or separated from the secondary transition chamber The first-stage valve cover 2 is fixedly connected to the first end, and a first-stage pressure sensitive element 5 is provided in the first-stage valve cover 2 and the first-stage low-pressure chamber 25, and the first-stage pressure sensitive element 5 closes the opening of the first-stage low-pressure chamber 25. The first-stage valve cover 2 elastic element is provided in the cavity of the first-stage valve cover 2, and one end of the first-stage elastic element 4 can contact with the first-stage pressure sensitive element 5, and the other end of the first-stage elastic element 4 can contact with a first-stage top screw 1 threadedly connected to the first-stage valve cover 2; the second-stage valve cover 14 is fixedly connected to the first end, and a second-stage pressure sensitive element 15 is provided in the second-stage valve cover 14 and the second-stage low-pressure chamber 26, and the second-stage pressure sensitive element 15 closes the opening of the second-stage low-pressure chamber 26, and the second-stage valve cover 14 elastic element is provided in the cavity of the second-stage valve cover 14, and one end of the second-stage elastic element 16 can contact with the second-stage pressure sensitive element 15, and the other end of the second-stage elastic element 16 can contact with a second-stage top screw 20 threadedly connected to the second-stage valve cover 14; the handle 21 is fixedly connected to one end of the second-stage top screw 20 extending out of the second-stage valve cover 14.

[0024] In a specific scheme, the first-level pressure regulating assembly includes a first-level valve seat assembly, a first-level valve needle 8 and a first-level supporting elastic element 9. The first-level valve seat assembly is fixedly arranged at the connection point between the first-level transition chamber and the first-level low-pressure chamber 25. The first-level valve needle 8 passes through the first-level valve seat assembly, and one end of the first-level valve needle 8 can contact the first-level pressure sensitive element 5, and a first-level supporting elastic element 9 is arranged between the other end of the first-level valve needle 8 and the bottom surface of the first-level transition chamber; the second-level pressure regulating assembly includes a second-level valve seat assembly, a second-level valve needle 11 and a second-level supporting elastic element 10. The second-level valve seat assembly is fixedly arranged at the connection point between the second-level transition chamber and the second-level low-pressure chamber 26. The second-level valve needle 11 passes through the second-level valve seat assembly, and one end of the second-level valve needle 11 can contact the second-level pressure sensitive element 15, and a second-level supporting elastic element 10 is arranged between the other end of the second-level valve needle 11 and the bottom surface of the first-level transition chamber.

[0025] The constant pressure reducing valve provided by the present invention forms a primary pressure reduction from the air inlet 24 to the primary low-pressure chamber 25: when the gas in the primary low-pressure chamber 25 is consumed, its internal pressure decreases. Due to the elastic force of the primary elastic element 4, K3*△X3 > P1*S1 + P2*S3 + K1*△X1. At this time, the primary transition chamber is in communication with the primary low-pressure chamber 25, and the gas is input from the air inlet to the primary low-pressure chamber 25, causing the pressure in the primary low-pressure chamber 25 to gradually increase. When the pressure in the primary low-pressure chamber 25 increases to satisfy P1*S1 + P2*S3 + K1*△X1 = K3*△X3, the primary pressure reduction reaches equilibrium, and at this time P2 < P1. The primary valve needle 8 contacts the primary valve seat assembly, separating the primary transition chamber from the primary low-pressure chamber 25. When the gas in the primary low-pressure chamber 25 is consumed again, the primary transition chamber and the primary low-pressure chamber 25 will be in communication again, and so on in a cycle; similarly, a secondary pressure reduction is formed from the primary low-pressure chamber 25 to the secondary low-pressure chamber 26: when the gas in the secondary low-pressure chamber 26 is consumed, its internal pressure decreases. Due to the elastic force of the secondary elastic element 16, K4*△X4 > P2*S2 + P3*S4 + K2*△X2. At this time, the primary transition chamber is in communication with the secondary low-pressure chamber 26, and the gas is input from the primary low-pressure chamber 25 to the secondary low-pressure chamber 26, causing the pressure in the secondary low-pressure chamber 26 to gradually increase. When the pressure in the secondary low-pressure chamber 26 increases to satisfy P2*S2 + P3*S4 + K2*△X2 = K4*△X4, the secondary pressure reduction reaches equilibrium, and at this time P3 < P2. The secondary valve needle 11 contacts the secondary valve seat assembly, separating the secondary transition chamber from the secondary low-pressure chamber 26. When the gas in the secondary low-pressure chamber 26 is consumed again, the secondary transition chamber and the secondary low-pressure chamber 26 will be in communication again, and so on in a cycle; where P1 is the inlet pressure, P2 is the pressure in the primary low-pressure chamber 25, P3 is the pressure at the air outlet 27, K1 is the elastic coefficient of the primary support elastic element 9, △X1 is the compression amount of the primary support elastic element 9, K2 is the elastic coefficient of the secondary support elastic element 10, △X2 is the compression amount of the secondary support elastic element 10, K3 is the elastic coefficient of the primary elastic element 4, △X3 is the compression amount of the primary elastic element 4, K4 is the elastic coefficient of the secondary elastic element 16, △X4 is the compression amount of the secondary elastic element 16, S1 is the sealing area of the primary valve needle 8, S2 is the sealing area of the secondary valve needle 11, S3 is the effective area of the primary low-pressure chamber 25, and S4 is the effective area of the secondary low-pressure chamber 26.

[0026] The constant pressure reducing valve provided by the present invention realizes a primary pressure reduction from the air inlet 24 to the primary low pressure chamber 25, a secondary pressure reduction from the primary low pressure chamber 25 to the air outlet 27, and a double pressure reduction from the air inlet 24 to the air outlet 27. Compared with a single pressure reduction, the influence of the pressure change of the air inlet 24 on the pressure change of the air outlet 27 can be effectively reduced, so that the output pressure and output flow of the constant pressure reducing valve are stable. Moreover, the handle 21 is fixedly connected to one end of the secondary top screw 20 extending out of the secondary valve cover 14. By rotating the handle 21, the length of the secondary top screw 20 extending into the secondary valve cover 14 can be adjusted, thereby adjusting the compression amount of the secondary elastic element 16, which is convenient for closing and opening the constant pressure reducing valve.

[0027] The primary pressure sensitive element 5 and the secondary pressure sensitive element 15 are diaphragms or pistons. When the primary pressure sensitive element 5 and the secondary pressure sensitive element 15 are diaphragms, Figure 1 As shown, the diaphragm can be elastically deformed, and the diaphragm is pressed on the first end of the valve body 22 by the primary valve cover 2, or on the second end of the valve body 22 by the secondary valve cover 14; when the primary pressure sensitive element 5 and the secondary pressure sensitive element 15 are pistons, the piston forms a sealed contact with the primary low-pressure chamber 25 or the secondary low-pressure chamber 26 in the circumferential direction, and can be driven by the primary elastic element 4 or the secondary elastic element 18 to move axially in the primary low-pressure chamber 25 or the secondary low-pressure chamber 26, thereby driving the axial movement of the primary valve needle 8 or the secondary valve needle 11. However, it is not limited to this, as long as the primary elastic element 4 can drive the primary pressure sensitive element 5 to deform or move, so that the primary pressure regulating assembly connects or separates the primary transition chamber and the primary low-pressure chamber 25, or the secondary elastic element 16 can drive the secondary pressure sensitive element 15 to deform or move, so that the secondary pressure regulating assembly connects or separates the secondary transition chamber and the secondary low-pressure chamber 26.

[0028] In another specific embodiment of the present invention, in order to more conveniently operate the constant pressure reducing valve and accurately close and open the constant pressure reducing valve, the constant pressure reducing valve also includes a limit assembly, which is arranged on the secondary valve cover 14, and is used to limit the rotation angle of the handle 21 and adjust the compression amount of the secondary elastic element 16, so that the secondary pressure regulating assembly connects or separates the secondary transition chamber and the secondary low-pressure chamber 26, thereby opening or closing the constant pressure reducing valve.

[0029] In another specific embodiment of the present invention, a primary elastic element 4 of the constant pressure reducing valve is provided with a primary pressing block 3 at one end thereof for contacting the primary top screw 1, and both ends of the primary pressing block 3 are in contact with the primary top screw 1 and the primary elastic element 4 respectively.

[0030] A secondary pressing block 18 is disposed at one end of the secondary elastic element 16 for contacting the secondary top screw 20 , and two ends of the secondary pressing block 18 are in contact with the secondary top screw 20 and the secondary elastic element 16 , respectively.

[0031] In another specific embodiment of the present invention, in order to conveniently realize the opening and closing of the constant pressure reducing valve according to different needs, the limit assembly of the constant pressure reducing valve includes a sleeve nut 17, the sleeve nut 17 is threadedly connected to the outside of the secondary valve cover 14, the handle 21 is movably sleeved outside the sleeve nut 17, and an opening limit portion 19 and a closing limit portion are provided at one end of the sleeve nut 17 close to the handle 21. A handle limit portion 23 is provided on the inner wall of one end of the handle 21 close to the sleeve nut 17, and the handle limit portion 23 moves between the opening limit portion 19 and the closing limit portion.

[0032] When the constant pressure reducing valve leaves the factory, the position of the first-stage valve needle 8 is pre-adjusted. After leaving the factory, according to the pressure requirement, the sleeve nut 17 is rotated to adjust the opening limit part 19 and the closing limit part to the appropriate position, so as to facilitate the installation of the handle 21 and conveniently realize the opening and closing of the constant pressure reducing valve.

[0033] In another specific embodiment of the present invention, the handle limiter 23, the opening limiter 19 and the closing limiter of the constant pressure reducing valve are all limit screws, and the opening limiter 19 and the closing limiter are both threadedly connected to the end surface of the sleeve nut 17. The handle limiter 23 is threadedly connected to the inner wall of one end of the handle 21 close to the sleeve nut 17.

[0034] In another specific embodiment of the present invention, the first-level valve seat assembly of the constant pressure reducing valve includes a first-level valve seat 6 fixedly arranged on the valve body 22, and a first-level sealing gasket 7 is also arranged between the first-level valve seat 6 and the valve body 22. A first-level air vent hole for passing a first-level valve needle 8 is formed on the first-level valve seat 6 and the first-level sealing gasket 7. One end of the first-level valve needle 8 is located in the first-level transition chamber to form a first-level sealing head, and the first-level sealing head can open or close the first-level air vent hole.

[0035] The secondary valve seat assembly includes a secondary valve seat 13 fixedly arranged on the valve body 22, and a secondary sealing gasket 12 is also arranged between the secondary valve seat 13 and the valve body 22. Both the secondary valve seat 13 and the secondary sealing gasket 12 are provided with secondary vent holes for passing the secondary valve needle 11. One end of the secondary valve needle 11 is located in the secondary transition chamber to form a secondary sealing head, and the secondary sealing head can open or close the secondary vent hole.

[0036] In another specific embodiment of the present invention, the primary valve cover 2 and the secondary valve cover 14 of the constant pressure reducing valve are both threadedly connected to the valve body 22 .

[0037] In another specific embodiment of the present invention, the primary elastic element 4, the secondary elastic element 16, the primary supporting elastic element 9 and the secondary supporting elastic element 10 are all springs.

[0038] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A constant pressure reducing valve, characterized in that: include: A valve body, wherein the two ends of the valve body are respectively a first end and a second end, the first end is provided with a first-level low-pressure chamber and a first-level transition chamber in sequence from the outside to the inside, the second end is provided with a second-level low-pressure chamber and a second-level transition chamber in sequence from the outside to the inside, an air inlet and an air outlet are provided on the side wall of the valve body, the air inlet, the first-level transition chamber, the first-level low-pressure chamber, the second-level transition chamber, the second-level low-pressure chamber and the air outlet are connected in sequence; a first-level pressure regulating assembly is provided at the connection between the first-level transition chamber and the first-level low-pressure chamber, and the compression amount of the first-level elastic element is adjusted by the first-level top screw, so that the first-level pressure regulating assembly can be connected or separated from the first-level transition chamber and the first-level low-pressure chamber; a second-level pressure regulating assembly is provided at the connection between the second-level transition chamber and the second-level low-pressure chamber, and the compression amount of the second-level elastic element is adjusted by the second-level top screw, so that the second-level pressure regulating assembly can be connected or separated from the second-level transition chamber and the second-level low-pressure chamber; A first-level valve cover, the first-level valve cover is fixedly connected to the first end, and a first-level pressure sensitive element is provided in the first-level valve cover and the first-level low-pressure chamber, the first-level pressure sensitive element closes the opening of the first-level low-pressure chamber, the first-level elastic element is provided in the cavity of the first-level valve cover, one end of the first-level elastic element can contact with the first-level pressure sensitive element, and the other end of the first-level elastic element can contact with a first-level top screw threadedly connected to the first-level valve cover; A secondary valve cover, the secondary valve cover is fixedly connected to the second end, and a secondary pressure sensitive element is provided in the secondary valve cover and the secondary low-pressure chamber, the secondary pressure sensitive element closes the opening of the secondary low-pressure chamber, the secondary elastic element is provided in the chamber of the secondary valve cover, one end of the secondary elastic element can contact with the secondary pressure sensitive element, and the other end of the secondary elastic element can contact with a secondary top screw threadedly connected to the secondary valve cover; A handle, the handle being fixedly connected to an end of the secondary top screw extending out of the secondary valve cover; It also includes a limit assembly, which is arranged on the secondary valve cover and is used to limit the rotation angle of the handle and adjust the compression amount of the secondary elastic element so that the secondary pressure regulating assembly connects or separates the secondary transition chamber and the secondary low-pressure chamber; The limiting assembly includes a sleeve nut, the sleeve nut is threadedly connected to the outside of the secondary valve cover, the handle is movably sleeved on the outside of the sleeve nut, an end of the sleeve nut close to the handle is provided with an opening limiting portion and a closing limiting portion, an inner wall of an end of the handle close to the sleeve nut is provided with a handle limiting portion, the handle limiting portion moves between the opening limiting portion and the closing limiting portion, the opening limiting portion and the closing limiting portion are both threadedly connected to the end surface of the sleeve nut, and the handle limiting portion is threadedly connected to the inner wall of an end of the handle close to the sleeve nut; and The first-level pressure regulating assembly includes a first-level valve seat assembly, a first-level valve needle and a first-level supporting elastic element. The first-level valve seat assembly is fixedly arranged at the connection point between the first-level transition chamber and the first-level low-pressure chamber. The first-level valve needle passes through the first-level valve seat assembly, and one end of the first-level valve needle can contact the first-level pressure sensitive element. The first-level supporting elastic element is arranged between the other end of the first-level valve needle and the bottom surface of the first-level transition chamber.

2. The constant pressure reducing valve according to claim 1, characterized in that: The secondary pressure regulating assembly includes a secondary valve seat assembly, a secondary valve needle and a secondary supporting elastic element. The secondary valve seat assembly is fixedly arranged at the connection point between the secondary transition chamber and the secondary low-pressure chamber. The secondary valve needle passes through the secondary valve seat assembly, and one end of the secondary valve needle can contact the secondary pressure sensitive element. The secondary supporting elastic element is arranged between the other end of the secondary valve needle and the bottom surface of the secondary transition chamber.

3. The constant pressure reducing valve according to claim 1, characterized in that: A first-level pressing block is provided at one end of the first-level elastic element for contacting the first-level top screw, and two ends of the first-level pressing block are respectively in contact with the first-level top screw and the first-level elastic element; A secondary pressing block is arranged at one end of the secondary elastic element for contacting the secondary top screw, and two ends of the secondary pressing block are respectively in contact with the secondary top screw and the secondary elastic element.

4. The constant pressure reducing valve according to claim 1, characterized in that: The primary pressure sensitive element and the secondary pressure sensitive element are diaphragms or pistons.

5. The constant pressure reducing valve according to claim 1, characterized in that: The handle limiting portion, the opening limiting portion and the closing limiting portion are all limiting screws.

6. The constant pressure reducing valve according to claim 2, characterized in that: The first-level valve seat assembly includes a first-level valve seat fixedly arranged on the valve body, a first-level sealing gasket is also arranged between the first-level valve seat and the valve body, a first-level air vent hole for passing the first-level valve needle is opened on the first-level valve seat and the first-level sealing gasket, and a first-level sealing head is formed at one end of the first-level valve needle located in the first-level transition chamber, and the first-level sealing head can open or close the first-level air vent hole.

7. The constant pressure reducing valve according to claim 2, characterized in that: The secondary valve seat assembly includes a secondary valve seat fixedly arranged on the valve body, a secondary sealing gasket is also arranged between the secondary valve seat and the valve body, and a secondary air vent hole for passing the secondary valve needle is formed on the secondary valve seat and the secondary sealing gasket. A secondary sealing head is formed at one end of the secondary valve needle located in the secondary transition chamber, and the secondary sealing head can open or close the secondary air vent hole.

8. The constant pressure reducing valve according to claim 1, characterized in that: The primary valve cover and the secondary valve cover are both threadedly connected to the valve body.

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