Pneumatic amplifier and positioner

Abstract

The invention provides a pneumatic amplifier and a positioner, which can enable a valve body of the pneumatic amplifier to rapidly move from a first position where a communication path connecting an output air pressure chamber and a supply air pressure chamber is closed to a second position where the communication path is opened, and the valve body is not easy to move to the second position side even if there is a rapid exhaust action. The pneumatic amplifier includes a valve body that passes through a communication path that communicates the output air pressure chamber and the supply air pressure chamber, is biased toward the moving body, and closes the communication path and the air flow path of the moving body from below. The valve body increases the opening degree of the communication path in a state where the air flow path is closed by being pressed by the moving body that moves downward, and increases the opening degree of the air flow path in a state where the communication path is closed by being separated from the moving body that moves upward. The pressure receiving member is connected to the valve body and the housing, and applies a downward force to the valve body by receiving the pressure of compressed air supplied to the pneumatic chamber. The valve body is provided with a through hole for communicating the air flow path or the output air pressure chamber with the facing chamber.

Description

Technical Field

[0001] The invention relates to a pneumatic amplifier and a positioner. Background Art

[0002] Pneumatic amplifiers used in positioners and other devices are configured to amplify and output an input air pressure signal (Patent Document 1). These amplifiers include a movable body connected to an input diaphragm and an output diaphragm, through which an air flow path connecting an output air pressure chamber formed within the housing and an exhaust chamber passes; and a valve body extending through a communication path connecting the output air pressure chamber and a supply air pressure chamber formed within the housing, closing at least one of the communication path and the air flow path.

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] Japanese Utility Model Application Laid-Open No. 63-56301 Summary of the Invention

[0006] [Problems to be solved by the invention]

[0007] In the pneumatic amplifier, when the valve body moves from a first position that closes the connecting passage to a second position that opens the connecting passage, the compressed air pressure in the supply air pressure chamber may sometimes become an obstacle, preventing rapid movement. As an invention for eliminating this undesirable situation, the inventors of the present application have invented a pneumatic amplifier (see Comparative Example 1 below), which is provided with a pressure-receiving member that, by receiving the compressed air pressure from the supply air pressure chamber, applies a force to the valve body in a direction from the first position toward the second position. The pneumatic amplifier is provided with an opposing chamber that faces the connecting passage via the supply air pressure chamber and is introduced into the atmosphere. With this structure, it is possible to quickly move from a first position that closes the connecting passage connecting the output air pressure chamber and the supply air pressure chamber to a second position that opens the connecting passage.

[0008] However, in the above structure, when the movable body and the valve body are separated due to the rapid exhaust action from the time when the air pressure of the amplified signal becomes high pressure, air with the air pressure of the amplified signal (high pressure) flows into the space above the valve body. Due to the above air pressure, the valve body is pressed toward the second position side, and the connecting path is sometimes opened unintentionally.

[0009] The object of the present invention is to enable the valve body of the pneumatic amplifier to be quickly moved from a first position closing a communication path connecting an output air pressure chamber and a supply air pressure chamber to a second position opening the communication path, and the valve body is not easily moved toward the second position even when there is a sudden exhaust action.

[0010] [Technical means to solve the problem]

[0011] In order to solve the above-mentioned problem, the pneumatic amplifier of the present invention amplifies the air pressure signal, and the pneumatic amplifier includes: a shell, an input air pressure chamber to which the air pressure signal is input, an output air pressure chamber arranged at a first direction side closer to the input air pressure chamber and outputting the amplified air pressure signal, a supply air pressure chamber arranged at a first direction side closer to the input air pressure chamber and to which the compressed air pressure supplied from the outside of the pneumatic amplifier is input, and a pressure regulating device extending from the output air pressure chamber to the first direction and reaching the supply air pressure chamber and connecting the output air pressure chamber with the supply air pressure chamber. The air flow path of the air pressure chamber is connected to the input diaphragm, and the air flow path of the air pressure chamber is connected to the output air pressure chamber, and the air is exhausted from the output air pressure chamber; the input diaphragm faces the input air pressure chamber, deforms in the first direction when the air pressure of the air pressure signal increases, and deforms in the second direction opposite to the first direction when the air pressure decreases; the movable body is connected to the input diaphragm, passes through the exhaust chamber and reaches the output air pressure chamber, moves in the first direction or the second direction in conjunction with the deformation of the input diaphragm, and has an air flow path passing through the first end connected to the output air pressure chamber and the second end connected to the exhaust chamber. ; an output diaphragm facing the output air pressure chamber, connected to the movable body, deforming in the first direction or the second direction in conjunction with the movement of the movable body, and the difference in area with the input diaphragm contributes to the amplification rate of the air pressure signal; a valve body passing through the connecting path, being forced in the second direction, closing the connecting path and the first end from the first direction side, and by being pressed by the movable body moving in the first direction, increasing the opening of the connecting path in the state of closing the first end, and by moving away from the movable body moving in the second direction, opening the connecting path in the state of closing the first end. and a pressure-bearing member connected to the valve body and the housing, which acts on the valve body in the first direction by receiving the compressed air pressure of the supply air pressure chamber, and a facing chamber opposite to the connecting path across the supply air pressure chamber is provided in the housing, and a through hole is provided in the valve body, which connects the air flow path with the facing chamber when the valve body is in a state of closing the first end, and connects the output air pressure chamber with the facing chamber when the valve body is away from the moving body and the first end is open.

[0012] As an example, the valve body is of a relief type, and when the air pressure of the amplified air pressure signal reaches a target air pressure obtained by amplifying the air pressure of the air pressure signal before amplification at a desired amplification factor, the relief type sets the opening of the connecting passage to the opening of the relief amount.

[0013] As an example, the pressure-receiving member is a diaphragm that separates the supply air pressure chamber from the facing chamber.

[0014] The positioner of the present invention includes: the pneumatic amplifier; and an electro-pneumatic conversion mechanism for outputting the air pressure signal before amplification to the pneumatic amplifier.

[0015] [Effects of the Invention]

[0016] Through the present invention, the valve body of the pneumatic amplifier can be quickly moved from a first position that closes the connecting path connecting the output air pressure chamber and the supply air pressure chamber to a second position that opens the connecting path, and even if there is a sudden exhaust action, the valve body is not easy to move toward the second position side. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural diagram of a positioner according to an embodiment of the present invention.

[0018] Figure 2 Yes Figure 1 Schematic cutaway end view of the balanced state of the air amplifier.

[0019] Figure 3 Yes Figure 1 Schematic cutaway end view of the air amplifier in the exhaust state.

[0020] Figure 4 Yes Figure 1 This is a schematic cutaway end view of the air amplifier in the stopped state of air supply and exhaust.

[0021] Figure 5 This is a schematic cutaway end view of the air amplifier of Comparative Example 1.

[0022] Figure 6 This is a schematic cutaway end view of the air amplifier of Comparative Example 2.

[0023] Figure 7 This is a schematic cutaway end view of an enlarged portion of the valve body for explaining forces associated with the valve body.

[0024] [Explanation of Symbols]

[0025] 10: Locator

[0026] 20: Electro-pneumatic conversion mechanism

[0027] 30: Pneumatic amplifier

[0028] 31: Shell

[0029] 31A: Input air pressure chamber

[0030] 31B: Lead-in Road

[0031] 31C: Exhaust chamber

[0032] 31D: Bias chamber

[0033] 31E: Output pressure chamber

[0034] 31F: Supply air pressure chamber

[0035] 31G: Connecting Road

[0036] 31H: Import path

[0037] 31I: Facing Room

[0038] 32A: Diaphragm

[0039] 32B: Diaphragm

[0040] 32C: Diaphragm

[0041] 35: Mobile

[0042] 35A: Air flow path

[0043] 35AA: First end

[0044] 35AB: Second end

[0045] 36: Valve body

[0046] 36A: Upper side valve

[0047] 36B: Lower valve

[0048] 36C: bottom end

[0049] 36D: Through hole

[0050] 37: Spring

[0051] 38: Compression member

[0052] 130: Pneumatic amplifier

[0053] 230: Pneumatic amplifier DETAILED DESCRIPTION

[0054] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The vertical and horizontal directions described below are set for convenience and are not intended to limit the installation directions of the pilot amplifier and positioner.

[0055] Figure 1The positioner 10 of the present embodiment shown includes an electro-pneumatic conversion mechanism 20 that converts an electrical signal specifying a valve opening from an external device 91, such as a regulator, into an air pressure signal Pn; and a pneumatic amplifier 30 that amplifies the air pressure signal Pn and outputs the amplified air pressure signal Pn as an amplified signal (also referred to as an output air pressure signal) Po to a flow control valve 95. The valve opening of the flow control valve 95 is controlled by the amplified signal Po. The air pressure of the air pressure signal Pn and the air pressure of the amplified signal Po may be referred to as air pressure Pn and air pressure Po, respectively.

[0056] The electro-pneumatic conversion mechanism 20 includes a nozzle flapper mechanism, which includes a flapper displaced by an actuator such as a motor, and a nozzle that ejects fluid facing the flapper. The nozzle flapper mechanism drives the actuator using an electrical signal from an external device 91, thereby displacing the flapper by an amount corresponding to the current value of the electrical signal. The nozzle flapper mechanism outputs the nozzle back pressure, which varies depending on the distance between the flapper and the nozzle tip, as an air pressure signal Pn. In this way, the electro-pneumatic conversion mechanism 20 converts the electrical signal into an air pressure signal Pn and outputs the converted air pressure signal Pn. The air pressure signal Pn is input to the pneumatic amplifier 30 via a pipeline.

[0057] like Figure 2 As shown, the air amplifier 30 includes: a housing 31, diaphragms 32A to 32C, a moving body 35, a valve body 36, a spring 37, and a pressure-receiving member 38. Figure 2 Although this is an end view, a portion of the outer contour visible from the back is preferably depicted using a dotted line (components arranged inside the housing 31) or a solid line (outline of the housing 31).

[0058] The housing 31 includes an input air pressure chamber 31A, an inlet passage 31B, an exhaust chamber 31C, a bias chamber 31D, an output air pressure chamber 31E, a supply air pressure chamber 31F, a communication passage 31G, an inlet passage 31H, and an opposing chamber 31I. Furthermore, diaphragms 32A and 32C and a pressure-receiving member 38 including the diaphragms are connected to the housing 31 and support them. Although not shown, the housing 31 may be composed of multiple components, with any two of the components each supporting the diaphragms 32A and 32C and the pressure-receiving member 38 by sandwiching them.

[0059] Diaphragm 32A separates input air pressure chamber 31A from exhaust chamber 31C below it. Diaphragm 32B separates exhaust chamber 31C from bias chamber 31D below it. Diaphragm 32C separates bias chamber 31D from output air pressure chamber 31E below it. Pressure-receiving member 38 separates supply air pressure chamber 31F from facing chamber 31I.

[0060] The air pressure signal Pn from the electro-pneumatic conversion mechanism 20 is input to the input air pressure chamber 31A via an introduction path 31B connected to the input air pressure chamber 31A. A moving body 35 is connected to a diaphragm 32A facing the input air pressure chamber 31A.

[0061] The movable body 35 is vertically movable and extends vertically through the diaphragm 32B and the diaphragm 32C located therebelow. The diaphragms 32B and 32C are connected to the movable body 35. With this structure, the movable body 35 passes through the exhaust chamber 31C and the bias chamber 31D and reaches the output air pressure chamber 31E. The movable body 35 can be constructed by combining multiple components. In this case, any two of the multiple components sandwich the diaphragms 32A to 32C, thereby connecting them to the movable body 35.

[0062] Inside the moving body 35, a T-shaped air flow path 35A connects the output air pressure chamber 31E on the lower side (first direction side) with the exhaust chamber 31C on the upper side (second direction side). At the lower end of the moving body 35, a first end 35AA of the air flow path 35A, connected to the output air pressure chamber 31E, opens downward. This lower end, or first end 35AA, faces the connecting passage 31G and, as described later, the valve body 36 that extends through the connecting passage 31G. At the upper end of the moving body 35, two second ends 35AB of the air flow path 35A, connected to the exhaust chamber 31C, open to the left and right.

[0063] The exhaust chamber 31C, which is connected to the air flow path 35A of the moving body 35, has both ends in the left and right directions open to the atmosphere, and the exhaust chamber 31C is at atmospheric pressure. As described later, the exhaust chamber 31C exhausts the air in the output air pressure chamber 31E exhausted through the air flow path 35A to the atmosphere.

[0064] The output air pressure chamber 31E and the supply air pressure chamber 31F are located below the input air pressure chamber 31A, the exhaust chamber 31C, and the bias chamber 31D. The output air pressure chamber 31E outputs an amplified signal Po, which is amplified by the air pressure and air flow of the air pressure signal Pn. The supply air pressure chamber 31F is supplied with compressed air pressure Ps supplied from outside the air amplifier 30.

[0065] The supply air pressure chamber 31F and the output air pressure chamber 31E are connected via a connecting passage 31G. The connecting passage 31G extends downward from the output air pressure chamber 31E and reaches the supply air pressure chamber 31F. The valve body 36 passes through the connecting passage 31G. In addition to flowing into the output air pressure chamber 31E via the connecting passage 31G, the compressed air at the compressed air pressure Ps of the supply air pressure chamber 31F also flows into the bias chamber 31D via the inlet passage 31H connected to the supply air pressure chamber 31F. The air pressure of the output air pressure chamber 31E, i.e., the air pressure of the amplified signal Po, is increased by the amount of compressed air flowing in, i.e., the amount corresponding to the opening of the connecting passage 31G, which will be described later. The air pressure of the bias chamber 31D is maintained at the compressed air pressure Ps.

[0066] The valve body 36 is configured to be movable in the up and down directions. The valve body 36 is urged upward, i.e., toward the movable body 35, by a spring 37. The valve body 36 is configured as a lift valve. The valve body 36 includes an upper valve 36A that abuts against the lower end of the movable body 35 and closes the first end 35AA of the air flow path 35A from below, and a lower valve 36B that closes the connecting path 31G from below. The valve body 36 includes a lower end 36C extending downward from the lower valve 36B. A pressure-bearing member 38 connected to the housing 31 is connected to the lower end 36C. The valve body 36 may be composed of, for example, a plurality of components, and may be connected to the pressure-bearing member 38 by clamping the pressure-bearing member 38 with any two of the plurality of components.

[0067] The valve body 36 also includes a through hole 36D extending through the valve body 36. The through hole 36D extends in the vertical direction. The lower end of the through hole 36D opens at the lower end surface of the valve body 36, which faces the opposing chamber 31I. The upper end of the through hole 36D opens at the upper end surface of the valve body 36. The upper end surface faces the air flow path 35A when the upper valve 36A of the valve body 36 is in the closed state, closing the first end 35AA of the air flow path 35A, and faces the output air pressure chamber 31E when the valve body 36 is in the open state. With this structure, the through hole 36D connects the air flow path 35A with the opposing chamber 31I when the through hole 36D is in the closed state. When the through hole 36D is in the open state, the output air pressure chamber 31E connects with the opposing chamber 31I.

[0068] The pressure-receiving member 38, which includes a diaphragm, separates the supply air pressure chamber 31F from the opposing chamber 31I, which faces the communication passage 31G via the supply air pressure chamber 31F. The pressure-receiving member 38 receives compressed air pressure Ps on its upper surface facing the supply air pressure chamber 31F, and receives air pressure PI of the opposing chamber 31I on its lower surface facing the opposing chamber 31I. The air pressure PI varies depending on whether the first end 35AA of the air flow path 35A is closed or opened by the upper valve 36A of the valve body 36. In the closed state, the air flow path 35A communicates with the opposing chamber 31I via the through-hole 36D, so the air pressure PI is the pressure of the air flow path 35A, that is, atmospheric pressure. On the other hand, in the open state, the output air pressure chamber 31E communicates with the opposing chamber 31I via the through-hole 36D, so the air pressure PI is the pressure of the output air pressure chamber 31E. Furthermore, in the closed state, the compressed air pressure Ps is higher than the atmospheric pressure Pair, and therefore a downward force acts on the valve body 36 due to the compressed air pressure Ps.

[0069] The air amplifier 30 configured as described above amplifies the air pressure of the air pressure signal Pn introduced into the input air pressure chamber 31A at a predetermined amplification factor. Hereinafter, the air pressure obtained by amplifying the air pressure signal Pn at the predetermined amplification factor is referred to as the target air pressure.

[0070] The difference in area between the diaphragm (input diaphragm) 32A facing the input air pressure chamber 31A and the diaphragm (output diaphragm) 32C facing the output air pressure chamber 31E contributes to the air pressure amplification factor. More specifically, the air pressure amplification factor is determined by the ratio of the effective area (the area of the region receiving air pressure in the vertical direction) of the pressure-receiving surface of the air pressure signal Pn in the combination of diaphragm (input diaphragm) 32A and movable body 35 to the pressure-receiving surface of the air pressure signal Po in the combination of diaphragm (output diaphragm) 32C and movable body 35.

[0071] The pneumatic amplifier 30 also amplifies the air flow rate of the air pressure signal Pn. This amplification is achieved by increasing the cross-sectional area of the output air pressure chamber 31E, the supply air pressure chamber 31F, the communication path 31G, the air flow path 35A, and the exhaust chamber 31C perpendicular to the air flow direction.

[0072] The pneumatic amplifier 30 is composed of a discharge type. Figure 2In the equilibrium state shown, valve body 36 is in the relief position, where it closes first end 35AA of air flow path 35A of moving body 35 and sets the opening of communication path 31G to an opening below a predetermined opening, i.e., an opening for the relief amount. Here, the relief position of valve body 36 is defined as a position where valve body 36 is away from the peripheral edge of the lower end of communication path 31G. However, the relief position may also be a position where lower valve 36B of valve body 36 closes communication path 31G, i.e., a position where valve body 36 contacts the peripheral edge of the lower end of communication path 31G (the uppermost position at which valve body 36 can be located). In this case, valve body 36 is provided with a relief hole that connects output air pressure chamber 31E and supply air pressure chamber 31F even when valve body 36 is in the position closing communication path 31G. Therefore, even when valve body 36 is in the relief position, communication path 31G is not completely closed (opened to the relief amount) by the relief hole. Thus, in a balanced state, compressed air at compressed air pressure Ps from the supply air pressure chamber 31F flows into the output air pressure chamber 31E at a constant amount, i.e., the desired discharge amount. Thus, the air pressure Po is maintained constant. Furthermore, in a balanced state, the upper valve 36A of the valve body 36 can be positioned in a discharge position (a slightly separated position, or a closed position if a discharge hole is provided) relative to the first end 35AA of the air flow path 35A.

[0073] When from Figure 2 As the air pressure signal Pn introduced into the input air pressure chamber 31A increases from the equilibrium state shown, the increase causes the diaphragm 32A to deform downward (not shown). The movable body 35 moves downward in conjunction with this deformation. The diaphragms 32B and 32C also deform downward in conjunction with the downward movement of the movable body 35. As the movable body 35 moves downward, it pushes the valve body 36 downward against the force of the spring 37. During this push, the first end 35AA of the air flow path 35A is closed by the upper valve 36A of the valve body 36. The downward movement of the valve body 36 causes the lower valve 36B to move downward, away from the communication path 31G. This increases the opening of the communication path 31G, increasing the compressed air pressure Ps flowing from the supply air pressure chamber 31F into the output air pressure chamber 31E. This state represents the air supply state, where compressed air is being supplied to the output air pressure chamber 31E. According to the air supply state, the air pressure of the amplified signal Po output from the supply air pressure chamber 31F increases by an amount corresponding to the opening of the communication path 31G. As the air pressure of the amplified signal Po approaches the target air pressure, the valve body 36 and the movable body 35 move upward, the opening of the communication path 31G by the valve body 36 decreases, and the air pressure of the amplified signal Po reaches the target air pressure, thereby the pneumatic amplifier 30 becomes Figure 2 equilibrium state.

[0074] In the case where the air pressure of the air pressure signal Pn decreases, as shown in FIG. Figure 3As shown, the diaphragm 32A is deformed in a concave manner upward, and the movable body 35 moves upward in conjunction with this. The diaphragm 32B and the diaphragm 32C are deformed upward in conjunction with the upward movement of the movable body 35. By the upward movement of the movable body 35, the movable body 35 is separated from the valve body 36, and the first end 35AA of the air flow path 35A of the movable body 35 is opened. During the opening, the valve body 36 closes the connecting path 31G. As a result, the air in the output air pressure chamber 31E is discharged to the atmosphere via the air flow path 35A and the exhaust chamber 31C. Therefore, the air pressure of the amplified signal Po drops. The state is an exhaust state in which the air in the output air pressure chamber 31E is exhausted (open to the atmosphere). As the air pressure of the amplified signal Po approaches the target air pressure, the movable body 35 gradually moves downward. The movable body 35 moving downward is as shown in FIG. Figure 4 As shown, the valve body 36 contacts the air flow path 35A and the communication path 31G. At this time, the air supply and exhaust are stopped, and the moving body 35 presses the valve body 36 downward. When the air pressure of the amplified signal Po reaches the target air pressure, the valve body 36 is configured in the release position, and the pneumatic amplifier 30 becomes Figure 2 equilibrium state.

[0075] In addition, when the valve body 36 is provided with a relief hole, no matter whether the air pressure of the air pressure signal Pn introduced into the input air pressure chamber 31A increases or decreases, when the air pressure reaches the target air pressure, Figure 4 The state becomes equilibrium.

[0076] In the embodiment, in order to make the transition from the exhaust state to the equilibrium state smooth, a pressure receiving member 38 is provided. First, referring to the pneumatic amplifier 130 ( Figure 5 ) and the pneumatic amplifier 230 of Comparative Example 2 ( Figure 6 ) The function of the pressure-receiving member 38 will be described. The inventors of the present application improved Comparative Example 2 to conceive of Comparative Example 1, and improved Comparative Example 1 to conceive of the present embodiment. Hereinafter, components having common functions in the pneumatic amplifier 30, the pneumatic amplifier 130, and the pneumatic amplifier 230 will be described with the same reference numerals. Compared to the pneumatic amplifier 30, the pneumatic amplifier 130 does not have a through hole 36D in the valve body 36. In addition, the opposing chamber 31I is open, and the atmospheric pressure Pair is supplied to the opposing chamber 31I. In the pneumatic amplifier 230, compared to the pneumatic amplifier 130, the lower end portion 36C of the valve body 36 is not provided, and the opposing chamber 31I is not provided. The basic operation caused by the increase or decrease of the air pressure of the air pressure signal Pn of the pneumatic amplifier 30, the pneumatic amplifier 130, and the pneumatic amplifier 230 is the same.

[0077] In exhaust state, it acts on Figure 6The force F1 in the vertical direction of the movable body 35 of the pneumatic amplifier 230 shown is calculated by the following equation (1). In the following equation (1), each diaphragm 32A to 32C is approximately flat (the same applies to other equations). Here, the downward force is assumed to be positive (the same applies hereinafter). Furthermore, An is the effective area of the pressure-receiving surface of the air pressure of the air pressure signal Pn in the combination of the diaphragm (input diaphragm) 32A and the movable body 35. Pn is the value of the air pressure of the air pressure signal Pn. As is the difference between the effective area of the pressure-receiving surface of the compressed air pressure Ps in the bias chamber 31D in the combination of the diaphragm 32B and the movable body 35 and the effective area of the pressure-receiving surface of the compressed air pressure Ps in the bias chamber 31D in the combination of the diaphragm 32C and the movable body 35. Ps is the value of the compressed air pressure Ps in the bias chamber 31D. Ao is the effective area of the pressure-receiving surface of the air pressure of the amplified signal Po in the combination of the diaphragm (output diaphragm) 32C and the movable body 35. Po is the value of the air pressure of the amplified signal Po.

[0078] F1=An*Pn-As*Ps-Ao*Po···(1)

[0079] Furthermore, the vertical force F2 acting on the movable body 35 in the supply and exhaust stop state transitioning from the exhaust state is calculated by the following equations (2) and (3) because the vertical force Fb received by the valve body 36 also acts on the movable body 35. In equation (3), Ps is the value of the compressed air pressure Ps within the supply air pressure chamber 31F, and Ab is the effective area of the pressure-receiving surface (here, the lower surface) of the valve body 36 that receives the compressed air pressure Ps in the position where the communication passage 31G is closed.

[0080] F2=F1-Fb···(2)

[0081] Fb=Ab*Ps···(3)

[0082] As can be seen from equation (2), from the moment the movable body 35 abuts the valve body 36, as long as the pressure at a certain point does not change by the difference between F1 and F2 (Fb = Ab*Ps) (i.e., the amount of force applied to the valve body 36), the movable body 35 and the valve body 36 will not begin to move together, i.e., transition to a balanced state. However, since the compressed air pressure Ps and the air pressure Pn cannot be intentionally changed, transition to a balanced state can only be achieved by waiting for the air pressure Po to decrease in the amount of discharge. This also takes time to achieve a balanced state, i.e., to stabilize the air pressure Po. Furthermore, when the air pressure Po drops to a level where the valve body 36 begins to move due to the pressure of the movable body 35, there are cases where the air pressure Po falls below the intended target air pressure. In this case, transition to a supply state may occur again, causing overshoot and requiring even longer time to stabilize.

[0083] Ab depends on the size of the valve body 36. However, if the valve body 36 is enlarged to increase the air supply capacity of the air amplifier 130, for example, the influence of Fb becomes even greater. Furthermore, in recent years, there has been a trend to set the compressed air pressure Ps higher to increase the pressure in the communication passage 31G used to close the valve body 36. From this perspective, the influence of Fb cannot be ignored. Furthermore, increasing the bleed volume by, for example, providing a larger bleed hole speeds up the setting, but this also increases the overall air consumption.

[0084] On the other hand, in Comparative Example 1, Figure 5 In the air supply and exhaust stop state, Fb can be expressed as the following equation (4) by the pressure-receiving member 38. Here, Adia is the area of the annular pressure-receiving member 38 surrounding the valve body 36 (the effective area when it is approximately flat). Ab is the effective area of the pressure-receiving surface of the valve body 36 (here, the lower surface of the lower valve 36B surrounding the lower end portion 36C) that receives the compressed air pressure Ps in the position where the communication passage 31G is closed.

[0085] Fb=(Ab-Adia)*Ps···(4)

[0086] As can be seen from equation (4), the compressed air pressure Ps received by the pressure-receiving member 38 exerts a downward force (Adia * Ps) on the valve body 36, reducing the value of Fb by the amount of this force. As a result, the time required for transition to equilibrium, i.e., the time required for the aforementioned settling, can be shortened compared to Comparative Example 2.

[0087] As described above, in Comparative Example 1, the pressure-receiving member 38 is provided. This pressure-receiving member 38 faces the communication passage 31G across the supply air pressure chamber 31F and is connected to the valve body 36 and the housing 31. By receiving the compressed air pressure from the supply air pressure chamber 31F, the pressure-receiving member 38 applies a force in the first direction to the valve body 36. This reduces the influence of the compressed air pressure Ps during the downward movement of the valve body 36. Consequently, the time required to reach equilibrium, i.e., the time required for the aforementioned settling, is shortened compared to a case where the pressure-receiving member 38 is not provided.

[0088] However, the inventors of this application have found that the following disadvantages also exist in Comparative Example 1. That is, in Comparative Example 1, when the air pressure Po of the amplified signal Po becomes high pressure and the exhaust operation is rapid (for example, when the air pressure Po becomes high pressure due to the rapid exhaust operation), the air pressure Po becomes high pressure and the exhaust operation is rapid. Figure 3(When the valve body 36 is in the open state, air at pressure Po flows into the space V above the valve body 36, applying a pressure equal to the air pressure Po to the upper end of the valve body 36. This pressure is greater than the atmospheric pressure Pair in the opposing chamber 31I, which presses the valve body 36 upward. Therefore, the difference in pressure pushes the valve body 36 downward, causing the communication path 31G to unintentionally open. As a result, an unexpected supply / exhaust open state occurs, in which the first end 35AA of the air flow path 35A of the moving body 35 and the communication path 31G are simultaneously open. In this supply / exhaust open state, the state in which the first end 35AA of the air flow path 35A is open, intended to lower the air pressure Po of the amplified signal Po, coexists with the opposite state, which is the state in which the communication path 31G is open, intended to raise the air pressure Po. Consequently, stable exhaust operation cannot be performed, or unnecessary supply air is wasted and released into the atmosphere. This can lead to unstable exhaust operation, resulting in problems such as a temporary loud sound of air flowing or a temporary increase in pressure that is intended to decrease. In addition, when the air supply port and the exhaust port are opened at the same time, if the flow is balanced when the air supply and exhaust are open, it becomes uncontrollable in a stable state. As long as it is not affected by certain external factors, the air pressure Po is constant, and the adverse situation of continuous large-scale leakage is also considered.

[0089] Therefore, in this embodiment, the air pressure in the space above the valve body 36 is introduced into the facing chamber 31I via the through-hole 36D of the valve body 36. This ensures that the downward pressure applied to the upper portion of the valve body 36 is substantially equal to the air pressure PI applied to the facing chamber 31I of the valve body 36 or the pressure-receiving member 38. As a result, the air pressure PI when the first end 35AA of the air flow path 35A is closed, such as in the equilibrium state or the air supply state, reaches atmospheric pressure. The air pressure PI when the first end 35AA is open, such as in the exhaust state, is substantially equal to the air pressure Po. Consequently, during the sudden exhaust operation, even if a pressure of the same magnitude as the air pressure Po is applied to the upper end of the valve body 36, the air pressure PI in the facing chamber 31I, which presses the valve body 36 upward, becomes substantially equal to the air pressure Po. This cancels the pressure applied to the upper end of the valve body 36, suppressing downward movement of the valve body 36 and preventing the unintended opening of the communication path 31G. Furthermore, when the first end 35AA of the air flow path 35A is closed, such as in the equilibrium state or the air supply state, the air pressure PI is at atmospheric pressure. In this case, the structure of the air amplifier 30 is the same as that of the air amplifier 130 of Comparative Example 1, and the same effects can be achieved. Specifically, the effect of shortening the transition time to the equilibrium state can be ensured.

[0090] Here, if Figure 7As shown, if Aex is set as the area of the upper surface of the upper end of the valve body 36 (the upward surface (including the surface approximately horizontal)), Fpo is set as the force in the vertical direction applied to the lower valve 36B of the valve body 36 by the air pressure Po, Fps is set as the force in the vertical direction applied to the lower valve 36B of the valve body 36 by the compressed air pressure Ps, Fsp is set as the force in the vertical direction applied to the valve body 36 from the spring 37, Fd is set as the vertical force applied to the pressure-receiving member 38 from the supply air pressure chamber 31F side, and Apde is set as the area of the lower surface of the pressure-receiving member 38 (the downward surface (including the surface approximately horizontal)) + the lower surface of the valve body 36 and the surface of the facing chamber 31I to which the air pressure PI is applied, then the upward force F3 (the upward direction is set to be positive) applied to the valve body 36 is calculated by the following formula (5).

[0091] F3=-Po*Aex-Fpo+Fps+Fsp-Fd+Po*Apde

[0092] =-Fpo+Fps+Fsp-Fd-Po(Aex-Apde)···(5)

[0093] As shown in the above formula (5), the pressures applied to the surface of Aex and the surface of Apde can be made common to Po through the through hole 36D of the valve body 36, so that the force applied to the upper surface of the upper end of the valve body 36 can be reduced by an amount equivalent to the difference between Aex and Apde. Accordingly, even if a sudden exhaust action occurs, the valve body 36 is not easy to move downward, and unnecessary opening of the connecting path 31G can be suppressed.

[0094] Furthermore, increasing the upward force applied to valve body 36, such as by increasing Fs, can also resolve the problem of communication passage 31G opening during abrupt exhaust operations. However, if this force is large, the force required by movable body 35 to move valve body 36 increases, prolonging the time from the moment movable body 35 strikes valve body 36 to reaching equilibrium, requiring time for settling. Alternatively, reducing Po*Aex can resolve the problem of communication passage 31G opening during abrupt exhaust operations. However, the maximum Po is a condition of use and cannot be changed based on the design. Aex is related to the maximum processing flow rate or operability, so it cannot be reduced simply to resolve this problem.

[0095] As described above, in the embodiment, a pressure-receiving member 38 is included, which is connected to the valve body 36 and the housing 31, and acts on the valve body 36 downward by receiving the compressed air pressure of the supply air pressure chamber 31F. The housing 31 is provided with an opposing chamber 31I that is opposite to the connecting path 31G across the supply air pressure chamber 31F, and the valve body 36 is provided with a through hole 36D. The through hole 36D allows the air flow path 35A to flow between the opposing chamber 31I when the valve body 36 closes the first end 35AA of the moving body 35, and allows the output air pressure chamber 31E to communicate with the opposing chamber 31I when the valve body 36 is away from the moving body 35 and the first end 35AA is opened. In this way, the air pressure above and below the valve body 36 can be made the same, and the valve body of the pneumatic amplifier can be quickly moved from the upper position where the connecting path 31G connecting the output air pressure chamber 31E and the supply air pressure chamber 31F is closed to the lower position where the connecting path 31G is opened. In addition, even if there is a sudden exhaust action, the valve body 36 is not easily moved to the lower position side.

[0096] In the above embodiment, a bleed-type air amplifier 30 has been described. Specifically, the valve body 36 is configured as a bleed-type valve body. When the air pressure of the amplified air pressure signal Pn, or the amplified signal Po, reaches the target air pressure obtained by amplifying the air pressure signal Pn before amplification at the desired amplification factor set for the air amplifier 30, the valve body 36 closes the first end 35AA of the air flow path 35A and opens the communication path 31G to release the air pressure. However, the air amplifier 30 may also be a non-bleed-type valve body. This configuration can also achieve the aforementioned effects. The pressure-receiving member 38 may also be implemented as a bellows or the like.

[0097] While the present invention has been described above with reference to the embodiments and variations, the present invention is not limited to these embodiments and variations. For example, the present invention encompasses various modifications of the embodiments and variations that would be understood by those skilled in the art within the scope of the technical concept of the present invention. Furthermore, the various structures listed in the embodiments and variations may be combined as appropriate within the scope of non-inconsistency.

Claims

1. A pneumatic amplifier for amplifying an air pressure signal, the pneumatic amplifier comprising: a housing having an input air pressure chamber to which the air pressure signal is input, an output air pressure chamber disposed closer to the first direction than the input air pressure chamber and outputting the amplified air pressure signal, a supply air pressure chamber disposed closer to the first direction than the input air pressure chamber and to which compressed air pressure supplied from outside the pneumatic amplifier is input, a communication path extending from the output air pressure chamber in the first direction to the supply air pressure chamber and connecting the output air pressure chamber with the supply air pressure chamber, and an exhaust chamber for exhausting air from the output air pressure chamber; an input diaphragm facing the input air pressure chamber, deforming in the first direction when the air pressure of the air pressure signal increases, and deforming in a second direction opposite to the first direction when the air pressure decreases; a movable body connected to the input diaphragm, penetrating the exhaust chamber and reaching the output air pressure chamber, moving in the first direction or the second direction in conjunction with the deformation of the input diaphragm, and having an air flow path passing through it having a first end connected to the output air pressure chamber and a second end connected to the exhaust chamber; an output diaphragm facing the output air pressure chamber, connected to the moving body, deforming in the first direction or the second direction in conjunction with the movement of the moving body, and having an area difference with the input diaphragm contributing to an amplification rate of the air pressure signal; a valve body passing through the communication passage and being biased in the second direction to close the communication passage and the first end from the first direction side, and increasing the opening of the communication passage with the first end closed by being pressed by the movable body moving in the first direction, and increasing the opening of the first end with the communication passage closed by being moved away from the movable body moving in the second direction; as well as a pressure-receiving member connected to the valve body and the housing, and applying a force in the first direction to the valve body by receiving the compressed air pressure from the supply air pressure chamber; The housing is provided with an opposing chamber facing the communication path across the supply air pressure chamber. The valve body is provided with a through hole, which connects the air flow path with the opposing chamber when the valve body closes the first end, and connects the output air pressure chamber with the opposing chamber when the valve body is away from the moving body and the first end is opened.

2. The pneumatic amplifier according to claim 1, wherein: The valve body is of a relief type, and when the air pressure of the amplified air pressure signal reaches a target air pressure obtained by amplifying the air pressure of the air pressure signal before amplification at a desired amplification factor, the relief type sets the opening of the communication path to the opening of the relief amount.

3. The pneumatic amplifier according to claim 1 or 2, wherein: The pressure receiving member is a diaphragm that separates the supply air pressure chamber from the facing chamber.

4. A locator, comprising: The pneumatic amplifier according to claim 1 or 2; as well as The electro-pneumatic conversion mechanism outputs the air pressure signal before amplification to the pneumatic amplifier.

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