CN111649017A

CN111649017A - Pneumatic amplifier

Info

Publication number: CN111649017A
Application number: CN202010619880.6A
Authority: CN
Inventors: 宋继忠; 刘能建; 伍友武; 吴伟荣
Original assignee: Suzhou Yingchuang Intelligent Technology Co ltd
Current assignee: Suzhou Yingchuang Intelligent Technology Co ltd
Priority date: 2020-07-01
Filing date: 2020-07-01
Publication date: 2020-09-11

Abstract

The invention discloses a pneumatic amplifier, which comprises a shell; the input chamber, the first air source chamber, the second air source chamber, the third air source chamber, the first air inlet chamber and the second air inlet chamber are formed in the shell; a lever rotatably connected with the housing; the input chamber is provided with a first diaphragm, the first air source chamber is provided with a second diaphragm, the first diaphragm and the second diaphragm are respectively connected to two ends of the lever, and the first diaphragm displaces according to the change of input air pressure introduced into the input chamber and drives the lever to rotate; the lever can drive the first valve rod to close the first exhaust channel or the first air inlet channel according to the change of input air pressure; or driving the second valve stem to close the second exhaust passage or the second intake passage. The pneumatic amplifier can compensate air source pressure fluctuation, has good output consistency, can quickly react to input air pressure, and has higher sensitivity.

Description

Pneumatic amplifier

Technical Field

The invention relates to a pneumatic technology, in particular to a pneumatic amplifier.

Background

The valve positioner is a main accessory of the regulating valve, is usually matched with a pneumatic regulating valve for use, receives an output signal of the regulator, controls the pneumatic regulating valve according to the output signal of the regulator, and after the regulating valve acts, the displacement of a valve rod is fed back to the valve positioner through a mechanical device, and the valve position condition is transmitted to an upper system through an electric signal.

The pneumatic amplifier is an important component of the valve positioner, and is configured to amplify the pneumatic control signal (input air pressure) Pn to be an output air pressure signal (output air pressure) Po and output the amplified signal to the regulating valve, so as to drive the valve rod of the regulating valve to move.

Currently, the pneumatic amplifier is generally classified into a single-action type pneumatic amplifier that outputs one output air pressure Po for one input air pressure Pn and a double-action type pneumatic amplifier that outputs two output air pressures Po1 and Po2 for one input air pressure Pn. The double-acting pneumatic amplifier has two output ports, and when the regulating valve is positively operated, the output air pressure Po1 of the first port is higher than the output air pressure Po2 of the second port; conversely, when the regulator valve is operated in the reverse direction, the output air pressure Po2 of the second port is higher than the output air pressure Po1 of the first port.

Fig. 6 shows a double-acting type pneumatic amplifier of the prior art in which a supply air pressure Ps supplies a left intake chamber 1, a right intake chamber 10, and a middle intake chamber 11 through air pipes, a diaphragm chamber 12 is used to let in an input air pressure Pn (nozzle back pressure), and a left output chamber 13 and a right output chamber 14 are respectively communicated with an upper chamber 101 and a lower chamber 102 of a regulator valve 100, as shown in fig. 7.

When the input air pressure Pn increases, the driving rod 15 moves leftward, so that the left deflation valve port 16 is closed, the left air intake valve port 17 is opened, and the supplied air pressure Ps enters the left output chamber 13 from the left air intake chamber 1 through the left air intake valve port 17 to drive the regulating valve to act; meanwhile, the right deflation valve port 18 is opened, the right intake valve port 19 is closed, and the gas discharged by the regulating valve passes through the right deflation valve port 18 and then is discharged from the valve rod exhaust hole 15a in the driving rod 15.

Likewise, when the input air pressure Pn decreases, the action of the pneumatic amplifier will be reversed from when the input air pressure Pn increases, which will drive the regulator valve in reverse.

The pneumatic amplifier in the prior art has the defects that firstly, the existing pneumatic amplifier jointly balances the driving rod 15 by input air pressure Pn and supply air pressure Ps, when an air source fluctuates, the supply air pressure Ps changes, the increment of the air source cannot be effectively balanced, and the driving rod can be caused to act, so that the reliable operation of the regulating valve is influenced, and the influence of the fluctuation of the air source is large; secondly, the existing pneumatic amplifier adopts a coaxial membrane structure, so that a forward pushing gap and a backward pushing gap easily exist, different lags and overshoots can be generated due to different response speeds under different air pressures, different amplification ratios are presented, and the control consistency is difficult to ensure; meanwhile, because the diaphragm groups have different static stresses under different air source pressure values and different generated static clearances, the zero position of the diaphragm groups is adjusted by the zero adjusting bolt 105 and the zero adjusting spring 106, so that the adjustment is difficult, and the springs at the two ends have unequal stress, so that the zero position consistency is poor; thirdly, since the components in the pneumatic amplifier inevitably have friction and other resistance during movement, the pneumatic amplifier generally needs to operate only when the input air pressure increases to a certain value, and the pneumatic amplifier has slow response and low sensitivity, and cannot perform operation quickly.

Disclosure of Invention

The present invention is directed to overcoming the above-mentioned drawbacks of the prior art and providing a pneumatic amplifier that compensates for fluctuations in the air supply and provides a more stable control of the regulator valve.

To achieve the above object, the present invention provides a pneumatic amplifier, which includes:

a housing;

a lever rotatably connected with the housing;

the lever comprises a shell, an input chamber, a first air inlet chamber and a second air source chamber, wherein the input chamber, the first air inlet chamber and the second air source chamber are formed in the shell and located at one end of the lever;

the first air source chamber, the second air inlet chamber and the third air source chamber are formed in the shell and located at the other end of the lever, the first air source chamber, the second air inlet chamber and the third air source chamber are located on two sides of the lever, a second exhaust channel is arranged between the second air inlet chamber and the outside, and a second air inlet channel is arranged between the second air inlet chamber and the third air source chamber;

the first diaphragm is positioned in the input chamber, displaces according to the change of input air pressure introduced into the input chamber, and drives the lever to rotate;

the second diaphragm is positioned in the first air source chamber, and the second diaphragm and the first diaphragm act on two ends of the lever respectively;

a first valve rod arranged in the first air inlet channel and a second valve rod arranged in the second air inlet channel;

the lever can drive the first valve rod to close the first exhaust channel according to the change of input air pressure, and simultaneously drive the second valve rod to close the second intake channel; or the first valve rod is driven to close the first air inlet channel according to the change of the input air pressure, and the second valve rod is driven to close the second air outlet channel at the same time.

In addition, the invention also provides the following auxiliary technical scheme:

the pneumatic amplifier further includes a first end cap securing the first diaphragm to the housing and a second end cap securing the second diaphragm to the housing, the input chamber being formed between the first end cap and the first diaphragm, the first air supply chamber being formed between the second end cap and the second diaphragm.

The pneumatic amplifier further comprises a first fixed seat connected with the shell, a third diaphragm and a first valve seat connected in the first fixed seat, and a first air inlet chamber is formed among the third diaphragm, the first fixed seat and the first valve seat.

The pneumatic amplifier further comprises a third end cover connected to the shell and a first spring steel sheet connected between the first fixing seat and the first valve rod, the first spring steel sheet provides force for driving the first valve rod to close the first air inlet channel, and a second air source cavity is formed among the third end cover, the first fixing seat and the first valve seat.

Pneumatic amplifier still including connect in first exhaust spare on the third diaphragm, first exhaust passage set up in the first exhaust spare, first valve rod with first exhaust spare offsets the back, first exhaust passage is sealed.

The lever is provided with a first abutting part, and the first exhaust part is sleeved on the first abutting part.

The pneumatic amplifier also comprises a second fixed seat connected with the shell, a third diaphragm and a second valve seat connected in the second fixed seat, and a second air inlet chamber is formed among the fourth diaphragm, the second fixed seat and the second valve seat.

The pneumatic amplifier further comprises a fourth end cover connected to the shell and a second spring steel sheet connected between the second fixed seat and the second valve rod, the second spring steel sheet provides force for driving the second valve rod to close the second air inlet channel, and a third air source cavity is formed among the fourth end cover, the second fixed seat and the second valve seat.

The pneumatic amplifier further comprises a second exhaust piece connected to the fourth diaphragm, the second exhaust channel is arranged in the second exhaust piece, and the second exhaust channel is closed after the second valve rod abuts against the second exhaust piece.

The lever is provided with a stud and a second abutting part in threaded connection with the stud, and the second exhaust part is connected with the second abutting part.

Compared with the prior art, the invention has the advantages that:

1. when the input air pressure of the pneumatic amplifier is unchanged and the air source fluctuates, the lever can perform reverse compensation action to compensate fluctuation influence, so that the operation of the regulating valve is more stable and reliable, and the consistency of control is improved;

2. the pneumatic amplifier is provided with the input chamber and the first air source chamber which are correspondingly arranged at the two ends of the lever, and due to the lever action, even if the input air pressure in the input chamber changes slightly, the input air pressure can also change greatly, so that the pneumatic amplifier can respond more quickly according to the input air pressure, and the sensitivity is higher;

3. the pneumatic amplifier can conveniently and accurately adjust the zero position, has high precision, quick response and timely control, can automatically compensate and improves the consistency of the zero position by arranging the position sensor for detecting the deflection position of the lever and the pressure sensor for detecting the air pressure of each chamber.

Drawings

Fig. 1 is a schematic cross-sectional view of a pneumatic amplifier of the present invention.

FIG. 2 is a schematic cross-sectional view of the pneumatic amplifier of the present invention at the input chamber and the first air source chamber.

Fig. 3 is an enlarged view of a portion a in fig. 1.

FIG. 4 is a schematic cross-sectional view of the pneumatic amplifier of the present invention at the second and third gas source chambers.

Fig. 5 is an enlarged view of a portion B in fig. 1.

Fig. 6 is a schematic diagram of a double-acting type pneumatic amplifier of the prior art.

FIG. 7 is a schematic view of a prior art regulator valve.

Detailed Description

The present invention will be described in further non-limiting detail with reference to the following preferred embodiments and accompanying drawings.

As shown in fig. 1, a pneumatic amplifier according to a preferred embodiment of the present invention includes a housing 2, a control membrane head assembly 3, an air supply membrane head assembly 4, a lever assembly 5, a first membrane valve assembly 6, and a second membrane valve assembly 7. Wherein, controlling membrane head subassembly 3 and first membrane valve unit spare 6 and corresponding the setting in the one end of lever assembly 5, air supply membrane head subassembly 4 and the corresponding setting in the other end of lever assembly 5 of second membrane valve unit spare 7.

The control membrane head assembly 3 includes a first end cap 30 connected to the casing 2 and a first diaphragm 31 connected to the casing 2, in this embodiment, the first end cap 30 is screwed on the casing 2, and a first convex ring 300 for pressing and fixing the outer circumference of the first diaphragm 31 on the casing 2 is provided. An input chamber 32 is formed between the first end cap 30 and the first diaphragm 31, the input chamber 32 being used for introducing an input air pressure Pn (nozzle back pressure), and it is opened with a first orifice 320 into which the input air pressure Pn is introduced, see fig. 2.

The air source membrane head assembly 4 is similar to the control membrane head assembly 3 in structure and comprises a second end cover 40 connected to the casing 2 and a second membrane 41 connected to the casing 2, and similarly, the second end cover 40 is screwed on the casing 2 and is provided with a second convex ring 400 for pressing and fixing the periphery of the second membrane 41 on the casing 2. A first air source chamber 42 is formed between the second end cap 40 and the second diaphragm 41, the first air source chamber 42 is communicated with an air source and is used for introducing the supply air pressure Ps, and a second hole passage 420 for introducing the supply air pressure Ps is formed in the first air source chamber 42, as shown in fig. 2.

The lever assembly 5 includes a lever 50 rotatably coupled to the housing 2, and a first valve head 51 and a second valve head 52 respectively coupled to both ends of the lever 50. A rotating shaft 20 is provided on the housing 2, and a lever 50 is connected to the rotating shaft 20 to be rotatable around the axis of the rotating shaft 20. The first valve head 51 is connected to the first diaphragm 31 and the second valve head 52 is connected to the second diaphragm 41. With the inlet chamber 32 and the first air supply chamber 42 vented, the diaphragm will deform under the influence of air pressure to abut the valve head and thereby urge the valve head to displace for operation.

As shown in fig. 3, the first membrane valve assembly 6 includes a first fixed seat 60 connected in the housing 2, a third diaphragm 61 pressed between the first fixed seat 60 and the housing 2, a first exhaust element 62 connected to the third diaphragm 61, a first valve seat 63 disposed in the first fixed seat 60, a first valve rod 64 disposed in the first fixed seat 60, a first spring steel plate 65 connected to the first fixed seat 60, and a third end cap 66 fixing the first spring steel plate 65 to the first fixed seat 60.

The third end cap 66 is screwed with the housing 2, and is provided with a third convex ring 660 for pressing the periphery of the first spring steel sheet 65 on the first fixed seat 60, and the third end cap 66 drives the first fixed seat 60 to press the third diaphragm 61 on the housing 2 while pressing the first spring steel sheet 65 on the first fixed seat 60.

The first exhaust element 62 may be formed integrally or by connecting a plurality of parts, in this embodiment, the first exhaust element 62 includes a first connector 620 and a second connector 621 screwed with each other, and the third diaphragm 61 is clamped and fixed between the two connectors. The first connector 620 and the second connector 621 are provided with a first exhaust passage 622 communicated with each other, and the first connector 620 is provided with a first exhaust hole 623 communicating the first exhaust passage 622 with the outside. The second connector 621 is further provided with a first step ring 624.

The first valve rod 64 is provided with a first sealing head 640 at one end and a second sealing head 641 at the other end. The first spring steel plate 65 is connected to the second sealing head 641, and has a small hole for ventilation. A second air supply chamber 67 is formed between the third end cap 66 and the first fixed seat 60 and the first valve seat 63, the second air supply chamber 67 is used for introducing the supply air pressure Ps, and is provided with a third hole 670 for introducing the supply air pressure Ps, as shown in fig. 4. A first air inlet chamber 68 is formed between the third diaphragm 61 and the first fixed seat 60 and the first valve seat 63, and the first air inlet chamber 68 is communicated with the upper chamber of the regulating valve and used for driving the regulating valve to act.

When the second sealing head 641 of the first valve rod 64 contacts the first valve seat 63, the first air inlet passage 630 of the first valve seat 63 is closed, and the first air inlet chamber 68 and the second air source chamber 67 are separated; on the contrary, the first air inlet chamber 68 and the second air source chamber 67 are communicated with each other, and at this time, the supply air pressure Ps in the second air source chamber 67 can enter the upper chamber of the regulating valve through the first air inlet chamber 68, so as to drive the regulating valve to act. When the first sealing head 640 of the first valve stem 64 contacts the first step ring 624, the first exhaust passage 622 is closed and the first intake chamber 68 is isolated from the outside atmosphere; conversely, the first inlet chamber 68 is open to the atmosphere, and gas in the upper chamber of the regulator valve can be exhausted through the first exhaust passage 622.

As shown in fig. 5, the second membrane valve assembly 7 has a structure identical to that of the first membrane valve assembly 6, and includes a second fixed seat 70 connected to the inside of the housing 2, a fourth diaphragm 71 pressed between the second fixed seat 70 and the housing 2, a second exhaust member 72 connected to the fourth diaphragm 71, a second valve seat 73 disposed in the second fixed seat 70, a second valve rod 74 disposed in the second fixed seat 70, a second spring steel sheet 75 connected to the second fixed seat 70, and a fourth end cap 76 for fixing the second spring steel sheet 75 to the second fixed seat 70.

Similarly, the first exhaust member 72 may be integrally formed, or may be formed by connecting the third connector 720 and the fourth connector 721, and the second exhaust member 72 is also provided with a second exhaust channel 722, a second exhaust hole 723 and a second step ring 724.

Similarly, the second valve rod 74 is provided with a third sealing head 740 at one end and a fourth sealing head 741 at the other end. The second spring steel sheet 75 is connected to the third sealing head 741, and has a hole for ventilation. A third air supply chamber 77 is formed between the fourth end cap 76 and the second fixed seat 70 and the second valve seat 73, the third air supply chamber 77 is used for introducing the supply air pressure Ps, and is provided with a fourth duct 770 for introducing the supply air pressure Ps, as shown in fig. 4. A second air inlet chamber 78 is formed between the fourth diaphragm 71 and the second fixed seat 70 and the second valve seat 73, and the second air inlet chamber 78 is communicated with the lower cavity of the regulating valve.

Similarly, when the fourth sealing head 741 of the second valve rod 74 contacts the second valve seat 73, the second air inlet passage 730 of the second valve seat 73 is closed, and the second air inlet chamber 78 and the third air source chamber 77 are isolated; on the contrary, the second air inlet chamber 78 and the third air source chamber 77 are communicated with each other, and at this time, the supply air pressure Ps in the third air source chamber 77 can enter the lower cavity of the regulating valve through the second air inlet chamber 78, so as to drive the regulating valve to act reversely. When the third sealing head 740 of the second valve stem 74 contacts the second step ring 724, the second exhaust passage 722 is closed and the second intake chamber 78 is isolated from the outside atmosphere; conversely, the second intake chamber 78 is open to the atmosphere, and gas in the lower chamber of the regulator valve can be exhausted through the second exhaust passage 722.

First valve rod 64 and second valve rod 74 all can be driven by lever 50, and specifically, first exhaust 62 and second exhaust 72 correspond respectively and set up in lever 50 both ends, and with lever 50 butt to when lever 50 takes place to rotate, can drive first exhaust 62 and the action of second exhaust 72. The lever 50 is provided with a first abutting member 500 and a second abutting member 502 at two ends thereof, the first abutting member 500 abuts against the first connector 620, and the second abutting member 502 abuts against the third connector 720. The first abutting member 500 and the second abutting member 502 may have the same structure or different structures, in this embodiment, the first abutting member 500 and the lever 50 are integrally formed, and the first connector 620 is sleeved on the first abutting member 500; the second abutting part 502 is an independent part, the stud 501 is arranged on the lever 50, and the second abutting part 502 is screwed on the stud 501, so that the height of the second abutting part 502 can be adjusted, the pushing distance of the lever 50 to the second valve rod 74 after rotation can be conveniently adjusted, and the pressure output by the amplifier to the two cavities of the pneumatic actuator can be further changed.

Specifically, when the input air pressure Pn in the input chamber 32 increases, the first diaphragm 31 will drive the lever 50 to rotate clockwise, the lever 50 will push the first exhaust element 62 to move, the first step ring 624 of the first exhaust element 62 will abut against the first valve stem 64, and the first exhaust element 62 will further push the first valve stem 64 to disengage from the first valve seat 63; at this time, the first air inlet chamber 68 is isolated from the outside atmosphere, the first air inlet chamber 68 is communicated with the second air source chamber 67, and the air in the second air source chamber 67 passes through the first air inlet chamber 68 and then is input into the upper cavity of the regulating valve, so that the regulating valve is driven to act. Meanwhile, the fourth diaphragm 71 drives the second exhaust member 72 to abut on the second abutment member 502 under the exhaust pressure of the regulator valve, and the second valve stem 74 contacts the second valve seat 73 by the elastic force of the second spring steel sheet 75. That is, at this time, the second intake chamber 78 is isolated from the third source chamber 77 and communicates with the outside atmosphere, the gas discharged from the lower chamber of the regulator valve can be discharged through the second discharge passage 722, the output pressure Po2 thereof is reduced, and the regulator valve is driven to operate.

Conversely, when the input air pressure Pn in the input chamber 32 decreases, the second diaphragm 41 will drive the lever 50 to rotate counterclockwise, and the lever 50 will push the second exhaust element 72 to move, so that the second step ring 724 of the second exhaust element 72 abuts against the second valve rod 74, and the second exhaust element 72 will further push the second valve rod 74 to disengage from the second valve seat 73; at this time, the second air inlet chamber 78 is isolated from the outside atmosphere, the second air inlet chamber 78 is communicated with the third air source chamber 77, and the air in the third air source chamber 77 is input into the lower cavity of the regulating valve through the second air inlet chamber 78 to drive the regulating valve to act. Meanwhile, the third diaphragm 61 abuts on the first abutment 500 under the exhaust pressure of the regulator valve, and the first valve stem 64 contacts with the first valve seat 63. That is, the first inlet chamber 68 is now isolated from the second source chamber 67 and is open to the atmosphere, and the valve upper chamber exhaust is able to vent through the first exhaust passage 622, reversing the valve action.

Preferably, the distance between the first valve head 51 and the rotating shaft 20 is greater than the distance between the second valve head 52 and the rotating shaft 20, in other words, the moment arm of the lever 50 driven by the first diaphragm 31 is greater than the moment arm of the second diaphragm 41, and a greater force can be generated to drive the lever 50 to act by a smaller input air pressure Pn, so that the response of the pneumatic amplifier is quicker and the sensitivity is higher; in addition, the cross-sectional area of the input chamber 32 may be set larger than the cross-sectional area of the first air supply chamber 42, which can further increase the thrust generated by the air pressure in the input chamber 32, further increasing the sensitivity and response speed.

The pneumatic amplifier is also provided with a position sensor for detecting the deflection angle of the lever 50, preferably a magnetic inductive Hall sensor, and a main control system (preferably an MCU) and a pressure sensor for detecting the air pressure value of each chamber (the input chamber 32, the first air source chamber 42, the second air source chamber 67 and the third air source chamber 77), wherein the pressure sensor and the Hall sensor are electrically connected with the main control system, can feed back a detection signal to the main control system, the main control system carries out real-time feedback control operation, can accurately adjust the zero position by detecting the position of the lever 50 and comparing the true zero position value of the valve, the air pressures of the input chamber 32, the first air source chamber 42, the second air source chamber 67 and the third air source chamber 77 tightly act on the lever 50, and can stably output by carrying out dynamic sampling operation on the change of various pressures, the automatic zero-position adjusting device has the advantages of high precision, quick response, timely control, automatic compensation, improvement of output consistency and overcoming of the defects that zero position cannot be automatically balanced and manual adjustment can only be carried out again after deviation due to various changes caused by prestress, mechanical property aging, air source fluctuation and the like of a spring of a traditional amplifier.

When the input air pressure of the pneumatic amplifier is unchanged and the air source fluctuates, the lever can perform reverse compensation action to compensate the fluctuation influence. For example, taking the state in which the second air supply chamber 67 communicates with the first air intake chamber 68 and is supplied with air by the regulator valve as an example, when the supply air pressure Ps increases due to air supply fluctuation, the air pressure input from the second air supply chamber 67 into the first air intake chamber 68 theoretically increases, so that the air pressure input into the regulator valve increases, and the stable operation of the regulator valve is affected. When the supply air pressure Ps is increased, the air pressure in the first input chamber 42 is increased at the same time, so that the driving lever 50 rotates counterclockwise, the first spring steel sheet 65 pushes the first valve rod 64 to move leftward, and the passage between the first valve rod 641 and the first valve seat 63 is closed, thereby offsetting the pressure increase input to the regulating valve caused by the increase of the supply air pressure Ps, realizing air pressure toggle compensation, and making the pneumatic amplifier more stable and reliable.

The pneumatic amplifier of the invention has at least the following advantages:

It should be noted that the above-mentioned preferred embodiments are merely illustrative of the technical concepts and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A pneumatic amplifier, characterized by: it includes:

a housing (2);

a lever (50) rotatably connected to the housing (2);

the air conditioner comprises an input chamber (32), a first air inlet chamber (68) and a second air source chamber (67) which are formed in the shell (2) and located at one end of the lever (50), wherein the input chamber (32), the first air inlet chamber (68) and the second air source chamber (67) are located on two sides of the lever (50), a first exhaust channel (622) is arranged between the first air inlet chamber (67) and the outside, and a first air inlet channel (630) is arranged between the first air inlet chamber (68) and the second air source chamber (67);

a first air source chamber (42), a second air inlet chamber (78) and a third air source chamber (77) which are formed in the shell (2) and located at the other end of the lever (50), wherein the first air source chamber (42), the second air inlet chamber (78) and the third air source chamber (77) are located on two sides of the lever (50), a second exhaust channel (722) is arranged between the second air inlet chamber (78) and the outside, and a second air inlet channel (730) is arranged between the second air inlet chamber (78) and the third air source chamber (77);

a first diaphragm (31) located in the input chamber (32), the first diaphragm (31) being displaced in response to a change in input air pressure into the input chamber (32) and driving the lever (50) to rotate;

a second diaphragm (41) located within the first air supply chamber (42), the second diaphragm (41) and the first diaphragm (31) acting on respective ends of the lever (50);

a first valve stem (63) disposed in the first air intake passage (630) and a second valve stem (73) disposed in the second air intake passage (730);

the lever (50) can drive the first valve rod (63) to close the first exhaust channel (622) according to the change of input air pressure, and simultaneously drive the second valve rod (73) to close the second air inlet channel (730); or the first valve rod (63) is driven to close the first air inlet channel (630) according to the change of the input air pressure, and the second valve rod (73) is driven to close the second air outlet channel (722) at the same time.

2. The pneumatic amplifier of claim 1, wherein: it further comprises a first end cap (30) securing the first diaphragm (31) to the housing (2) and a second end cap (40) securing the second diaphragm (41) to the housing (2), the input chamber (32) being formed between the first end cap (30) and the first diaphragm (31), the first gas supply chamber (42) being formed between the second end cap (40) and the second diaphragm (41).

3. The pneumatic amplifier of claim 1, wherein: the air inlet valve further comprises a first fixed seat (60) connected with the shell (2), a third diaphragm (61) and a first valve seat (63) connected into the first fixed seat (60), wherein a first air inlet chamber (68) is formed among the third diaphragm (61), the first fixed seat (60) and the first valve seat (63).

4. The pneumatic amplifier of claim 3, wherein: the valve further comprises a third end cover (66) connected to the shell (2) and a first spring steel sheet (65) connected between the first fixing seat (60) and the first valve rod (63), the first spring steel sheet (65) provides force for driving the first valve rod (63) to close the first air inlet channel (630), and a second air source chamber (67) is formed among the third end cover (66), the first fixing seat (60) and the first valve seat (63).

5. The pneumatic amplifier of claim 3, wherein: it still including connect in first exhaust spare (62) on third diaphragm (61), first exhaust passage (622) set up in first exhaust spare (62), first valve rod (63) with first exhaust spare (62) offset the back, first exhaust passage (622) is sealed.

6. The pneumatic amplifier of claim 5, wherein: the lever (50) is provided with a first abutting part (500), and the first exhaust part (62) is sleeved on the first abutting part (500).

7. A pneumatic amplifier according to any one of claims 1 to 6, wherein: the air inlet valve further comprises a second fixed seat (70) connected with the shell (2), a third diaphragm (61) and a second valve seat (73) connected into the second fixed seat (70), and a second air inlet chamber (78) is formed among the fourth diaphragm (71), the second fixed seat (70) and the second valve seat (73).

8. The pneumatic amplifier of claim 7, wherein: the air-supply valve further comprises a fourth end cover (76) connected to the shell (2) and a second spring steel sheet (75) connected between the second fixing seat (70) and the second valve rod (73), the second spring steel sheet (75) provides force for driving the second valve rod (73) to close the second air inlet channel (730), and a third air supply cavity (77) is formed among the fourth end cover (76), the second fixing seat (70) and the second valve seat (73).

9. The pneumatic amplifier of claim 8, wherein: the valve further comprises a second exhaust member (72) connected to the fourth diaphragm (71), the second exhaust channel (722) is arranged in the second exhaust member (72), and after the second valve rod (73) abuts against the second exhaust member (72), the second exhaust channel (722) is closed.

10. The pneumatic amplifier of claim 9, wherein: the lever (50) is provided with a stud (501) and a second abutting piece (502) which is screwed on the stud (501), and the second exhaust piece (72) is connected with the second abutting piece (502).