Pressure regulating valve

Abstract

To provide a pressure regulating valve capable of reducing frequency of hunting of a valve element to a valve seat and securely maintaining high responsiveness to minute pressure change by using a pressure sensing bellows.SOLUTION: A pressure regulating valve 100a includes: a valve body 10; a valve element 20; energizing means comprising an adjustment spring 41 and a pressure sensing bellows 51; a position adjustment part; and hunting frequency reduction means for setting an effective pressure receiving diameter Dx of the pressure sensing bellows 51 to be larger than a hole diameter Dv of a valve port 1A. In the valve closing state, force Fa of primary side pressure P1 acting on the valve element 20 and force Fd of secondary side pressure P2 acting on an effective pressure receiving surface of the pressure sensing bellows 51 are applied in a valve opening direction, and force Fb of inner pressure P0 of the pressure sensing bellows 51 acting on the valve element 20, force Fc of the secondary side pressure P2 acting on the valve element 20 and energizing force Fk of the pressure sensing bellows 51 itself and the adjustment spring 41 are applied in a valve closing direction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a pressure regulating valve equipped with a pressure-sensitive bellows and a hunting frequency reducing means. [Background technology]

[0002] Some pressure regulating valves are equipped with a pressure-sensitive bellows to provide high responsiveness to minute pressure changes.

[0003] For example, Patent Document 1 describes a pressure regulating valve 900 (hereinafter referred to as a "conventional pressure regulating valve") that is disposed via an O-ring Or in a piping block B in which a primary-side flow path Fp1 and a secondary-side flow path Fp2 are formed, as shown in Fig. 9. Patent Document 1 also describes the conventional pressure regulating valve 900 as comprising: a valve seat portion 912 having a primary-side port 1A and a valve seat 912a that communicate with the primary-side flow path Fp1; a main body 911 having a secondary-side port 1B that communicates with the secondary-side flow path Fp2; a valve element 920 that moves in the direction of an axis L and is seated on or unseated from the valve seat 912a; a pressure-sensing bellows 951 that is disposed between the other end of the valve element 920 and the main body 911; and an adjustment spring 941 and a slide unit 930 that are provided in an internal space 951a of the pressure-sensing bellows 951.

[0004] Here, in the conventional pressure regulating valve 900, secondary pressure P2 is introduced into the external space of the pressure-sensing bellows 951, and therefore the valve has high responsiveness to changes in secondary pressure P2. For this reason, the conventional pressure regulating valve 900 has a problem in that the valve opens and closes repeatedly in response to minute changes in secondary pressure P2, that is, hunting.

[0005] To solve this problem, in the conventional pressure regulating valve 900, the effective pressure-receiving diameter area Sx of the pressure-sensing bellows 951 is made to match the pressure-receiving area Sv calculated based on the diameter Dv of the valve port, which is the primary side port 1A (Sx = Sv), that is, the effective pressure-receiving diameter Dx of the pressure-sensing bellows 951 is made to match the diameter Dv of the valve port (Dx = Dv), thereby canceling out the influence of the secondary side pressure P2 and eliminating the influence of the secondary side pressure P2.

[0006] However, in the conventional pressure regulating valve 900, when the primary pressure P1 exceeds the set valve-open pressure and the valve is in an open state, a pressure change occurs around the valve disc 920. Specifically, as shown in FIG. 9 , around the valve disc 920, the primary pressure P1 decreases due to the outflow of fluid, while the secondary pressure P2 increases due to the inflow of fluid. At this time, as will be described in detail later, because the effective pressure-receiving diametric area Sx of the pressure-sensing bellows 951 matches the pressure-receiving area Sv calculated based on the valve port diameter Dv, the external force F acting in the valve opening direction of the valve disc 920 decreases relatively significantly, and the valve disc 920 moves in the valve closing direction. Thereafter, at the moment the valve is in a closed state, the primary pressure P1 exceeds the set valve-open pressure, and the valve is again in an open state. As described above, in the conventional pressure regulating valve 900, there is still a risk of hunting occurring relatively frequently immediately after the valve is opened (hereinafter referred to as "problem of the prior art (frequent hunting occurring immediately after the valve is opened)").

[0007] In the conventional pressure regulating valve 900, in order to solve the conventional problem (frequent hunting occurring immediately after the valve is opened), an elastic member 970 is provided on one end side of the valve body 920, and this elastic member 970 generates sliding resistance against the inner surface 912b of the valve seat portion 912.

[0008] However, in the conventional pressure regulating valve 900, the elastic member 970 constantly generates sliding resistance against the movement of the valve element 920 in the direction of the axis L, which reduces the responsiveness of the pressure-sensing bellows 951 to minute pressure changes, and also creates new problems such as an increase in the number of parts such as the elastic member 970, and the generation of turbulence in the fluid by the elastic member 970. Therefore, as with the conventional pressure regulating valve 900, it is not possible to employ the elastic member 970 in order to solve the conventional problem (frequent hunting occurring immediately after the valve is opened). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent application No. 2023-109159 Summary of the Invention [Problem to be solved by the invention]

[0010] An object of the present invention is to provide a pressure regulating valve that reduces the frequency of hunting of the valve body against the valve seat and can reliably maintain high responsiveness to minute pressure changes due to the pressure-sensing bellows. [Means for solving the problem]

[0011] In order to solve the above problems, a pressure regulating valve includes a valve body having a primary side port communicating with a valve port, a secondary side port, and a valve seat surrounding the valve port, a valve element that moves in an axial direction and seats on or leaves the valve seat, a biasing means that is arranged in the axial direction between the other end side of the valve element and the valve body, a position adjusting unit that can adjust the biasing force of the biasing means, and a hunting frequency reducing means that reduces the frequency of hunting of the valve element against the valve seat, the biasing means comprising an adjusting spring and a pressure-sensitive bellows, In this state, the valve element is subjected to a force acting on it from the primary pressure in the valve opening direction, and a force acting on the effective pressure-receiving surface of the pressure-sensing bellows from the secondary pressure, and a force acting on it from the internal pressure of the pressure-sensing bellows in the valve closing direction, and a force acting on it from the secondary pressure, and the biasing forces of the pressure-sensing bellows itself and the adjusting spring, and the hunting frequency reduction means sets the effective pressure-receiving diameter of the pressure-sensing bellows to be larger than the diameter of the valve port.

[0012] Furthermore, in the above-described pressure regulating valve, the valve body may include a main body having the secondary side port, and a valve seat portion that is separate from the main body, is arranged at one end of the main body, and has the primary side port and the valve seat, and the position adjustment portion may be configured to be able to adjust the relative axial positions of the valve seat portion and the main body.

[0013] Moreover, the pressure regulating valve may further include a slide unit provided in the sealed space of the pressure-sensing bellows, the slide unit including a cylindrical cylinder member fixed to the valve body, and a piston member fixed to the main body and supported so as to be movable forward and backward relative to the cylinder member, wherein an internal cylinder space is defined by the cylinder member, the piston member, and the valve body, and the hunting frequency reduction means may be configured to constantly communicate the internal cylinder space with the sealed space.

[0014] Moreover, the pressure regulating valve may further include a slide unit provided in the internal space of the pressure-sensing bellows, the slide unit having a communication hole and including a bellows top cover fixed to the valve body, and a connecting rod connected to the valve body and supported so as to be movable forward and backward relative to the bellows top cover, and the hunting frequency reduction means may be configured to constantly communicate the internal space of the pressure-sensing bellows with the atmosphere. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a pressure regulating valve that reduces the frequency of hunting of the valve body against the valve seat and can reliably maintain high responsiveness to minute pressure changes due to the pressure-sensing bellows. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a vertical cross-sectional view showing a pressure regulating valve according to a first embodiment of the present invention. [Figure 2] 2 is a cross-sectional view showing a state in which the pressure regulating valve shown in FIG. 1 is attached to a piping block. [Figure 3] 3 is an explanatory diagram of an external force acting on a valve element when the pressure regulating valve shown in FIG. 2 is in an open state. FIG. [Figure 4] FIG. 4 is an enlarged view of the area surrounded by the dashed line IV shown in FIG. 3. [Figure 5] 1A and 1B are diagrams explaining the mechanism of hunting occurrence in a conventional pressure regulating valve, where (a) and (b) represent condition 1 (Sv>Sx), (c) and (d) represent condition 2 (Sv=Sx), and (a) and (c) are time-pressure characteristic diagrams, and (b) and (d) are time-external force acting in the valve opening direction characteristic diagrams. [Figure 6]FIG. for explaining condition 3 (Sv < Sx), which is a means (1) for reducing hunting frequency in the pressure regulating valve according to the first embodiment. FIGS. (a) and (b) represent condition 3-1 (-ΔP1×Sv + ΔP2×(Sx - Sv) < 0), and FIGS. (c) and (d) represent condition 3-2 (-ΔP1×Sv + ΔP2×(Sx - Sv) ≧ 0). FIGS. (a) and (c) are time-pressure characteristic diagrams, and FIGS. (b) and (d) are time-external force acting in the valve opening direction characteristic diagrams. [Figure 7] Vertical cross-sectional view showing a pressure regulating valve according to a second embodiment of the present invention. [Figure 8] An enlarged view of the region surrounded by the broken line VIII shown in FIG. 7, and an explanatory diagram of the external force acting on the valve body in the valve open state. [Figure 9] Cross-sectional view showing a pressure regulating valve according to the prior art.

Mode for Carrying Out the Invention

[0017] Embodiments of the present invention will be described in detail with reference to FIGS. 1 to 8. However, the present invention is not limited to the aspects of this embodiment. [[ID=**********]] [[ID=**********]]

[0018] [[ID=**********]] [[ID=**********]] ​In this specification and the claims, the terms "left," "right," "upper," and "lower" refer to the directions shown in Figures 1 to 4 and 7 to 8. In this specification and the claims, the terms "one end" and "other end" refer to the "lower end" and "upper end" in the drawings. In this specification and the claims, the term "position adjustment unit" refers to a configuration that allows adjustment of the relative axial positions of the valve seat and the main body. In this specification and the claims, the term "effective pressure-receiving area of ​​the pressure-sensing bellows" refers to the area of ​​the deformation region where effective axial deformation occurs when viewing the pressure-sensing bellows from the axial direction. Specifically, this refers to the area of ​​the ring-shaped effective pressure-receiving surface from the minimum inner diameter of the bellows (the inner diameter of the "valve" portion of the bellows that protrudes toward the axial side of the pressure-sensing bellows) to a specified region radially outward, and is determined by calculation or testing. In this specification and claims, the term "effective pressure-receiving diameter of the pressure-sensitive bellows" refers to the deformation area in which axial deformation effectively occurs in the pressure-sensitive bellows, i.e., the outer diameter of the ring-shaped effective pressure-receiving surface. In this specification and claims, the term "effective pressure-receiving diameter area of ​​the pressure-sensitive bellows" refers to the circular area formed by the effective pressure-receiving diameter of the pressure-sensitive bellows when viewed from the axial direction. In this specification and claims, the term "hunting" refers to the phenomenon in which the valve disc quickly seats and unseats on the valve seat, repeatedly switching between a closed state and an open state. In this specification and claims, the term "hunting frequency reduction means" refers to a means for reducing the frequency of hunting of the valve disc against the valve seat. In claim 1, the term "internal pressure of the pressure-sensitive bellows" refers to pressures lower than atmospheric pressure, atmospheric pressure, and pressures higher than atmospheric pressure.

[0019] (First embodiment) <Configuration of pressure regulating valve> A pressure regulating valve 100a according to a first embodiment of the present invention will be described using Figure 1. The pressure regulating valve 100a is mainly composed of a valve body 10, a valve element 20, a slide unit 30, an adjusting spring unit 40, and a pressure-sensing bellows unit 50. Each component of the pressure regulating valve 100a will be described in order below. Note that a high primary pressure P1 is introduced into a primary port 1A, while a low secondary pressure P2 is introduced into a secondary port 1B.

[0020] As will be described in detail later, the pressure regulating valve 100a of the first embodiment has a hunting frequency reduction means (1) in which the effective pressure-receiving diameter Dx of the pressure-sensing bellows 51 is set to be larger than the diameter Dv of the valve port 1A (Dx>Dv), thereby eliminating the conventional problem (high-frequency hunting occurring immediately after the valve is opened) and reliably maintaining high responsiveness to minute pressure changes.

[0021] The valve body 10 is made of a metal such as stainless steel or aluminum, and comprises a main body 11 having a cylindrical shape with a bottom, and a valve seat portion 12 that is formed separately from the main body 11 and has an approximately cylindrical shape.

[0022] The main body 11 defines an accommodation chamber A therein, and has a side wall with a plurality of (for example, four) horizontal holes 11a that are uniformly arranged in the circumferential direction as viewed from the direction of the axis L and define the secondary side port 1B. In addition, a crimped hole 11o that is coaxial with the axis L is formed in the other end 11u of the main body 11.

[0023] The valve seat portion 12 includes an annular valve seat 12a, an inner peripheral surface 12b that defines the primary side port 1A, which is a valve port, and a pair of rotary tool insertion portions 12d formed on one end side and arranged at symmetrical positions across the axis L.

[0024] The valve element 20 is made of a metal such as stainless steel or phosphor bronze and has a generally circular disk shape. The valve element 20 includes an annular valve portion 21 and a recessed bowl portion 22 provided on the other end surface.

[0025] The valve portion 21 has an outer diameter larger than the valve seat 12a, and moves in the direction of the axis L to seat on or separate from the valve seat 12a.

[0026] The slide unit 30 includes a cylindrical cylinder member 31 fixed to the valve body 20 at one end, a connecting member 32 abutted against a bellows top cover 52 at the other end by the biasing force of an adjustment spring 41, and a piston member 33 whose other end is fixed to the connecting member 32 by crimping and supported so as to be movable forward and backward relative to the cylinder member 31, and is provided in an internal space 51a of the pressure-sensing bellows 51. Here, the adjustment spring 41 is sandwiched in a pressed state between the cylinder member 31 and the connecting member 32. Therefore, the slide unit 30 transmits the biasing force of the adjustment spring 41 to the pressure-sensing bellows 51, thereby biasing the pressure-sensing bellows 51 in the expansion direction along the axis L.

[0027] The adjustment spring unit 40 includes an adjustment spring 41 (biasing means) which is a compression spring, and an adjustment screw portion 42 which is a position adjustment portion that can adjust the biasing force on the valve body 20 by expanding and contracting the adjustment spring 41 and the pressure-sensing bellows 51.

[0028] The adjustment screw portion 42 is composed of a female thread portion 42a formed on the inner circumferential surface of one end of the main body 11 and a male thread portion 42b formed on the outer circumferential surface of the valve seat portion 12, which are screwed together. An adjustment jig (not shown) is engaged with the pair of rotary tool insertion portions 12d, and the valve seat portion 12 is rotated and moved in the axial direction L relative to the main body 11 via the adjustment screw portion 42, thereby adjusting the expansion and contraction of the adjustment spring 41 and the pressure-sensing bellows 51, i.e., the biasing force on the valve element 20. Thereafter, the valve seat portion 12 and one end of the main body 11 are fixed together via a weld W.

[0029] The pressure-sensing bellows unit 50 is made of a metal such as stainless steel or phosphor bronze, and includes a pressure-sensing bellows 51 (actuating means) formed by press molding into a bellows shape extending in the direction of the axis L, and a bellows top cover 52 having an approximately circular plate shape.

[0030] One end of the pressure-sensing bellows 51 is welded to the other end surface of the outer periphery of the valve body 20, and the other end is welded to one end surface of the outer periphery of the bellows top cover 52, sealing the inside.

[0031] As will be described in detail later, as shown in FIG. 3, the effective pressure-receiving diameter Dx of the pressure-sensing bellows 51 is set larger than the bore diameter Dv of the valve port 1A (Dx > Dv). This allows the external force F acting in the valve-opening direction of the valve disc 20, corresponding to the pressure change from State 1 (immediately after the valve is opened) to State 3 (a state in which the valve disc is balanced after movement due to the pressure change) shown in FIGS. 6(a) and 6(c), to be slightly reduced (see F1 → F2 → F3 (3-1) in FIG. 6(b)) or significantly increased (see F1 → F2 → F3 (3-2) in FIG. 6(d)). This eliminates the conventional problem of frequent hunting occurring immediately after the valve is opened. Note that the effective pressure-receiving diameter Dx of the pressure-sensing bellows 51 refers to the deformation region Dr where deformation in the axial direction L of the pressure-sensing bellows 51 effectively occurs, i.e., the outer diameter of the ring-shaped effective pressure-receiving surface, and is determined by calculation or testing.

[0032] In addition, the bellows top cover 52 has a boss portion 52a that protrudes from the other end side on the same axis as the axis L, and this boss portion 52a is fitted into the crimping hole 11o of the main body 11, and then a crimping portion Cr is formed by crimping processing, and the boss portion 52a is fixed to the main body 11.

[0033] <Installation of pressure regulating valve> First, the shapes of the main body 11 and the piping block B will be described with reference to FIG.

[0034] The main body 11 is formed with an expanded diameter portion 11L, a central portion 11c, and a reduced diameter portion 11S along the axis L from one end 11d to the other end 11u, and the outer diameter gradually decreases. Here, a continuously connected constricted portion 11n is formed between the expanded diameter portion 11L and the central portion 11c. In addition, a male threaded portion 11Scm that is threadedly engaged with the piping block B is formed on the outer peripheral surface of the other end of the central portion 11c.

[0035] Next, the piping block B has an insertion hole along the axial line L, and a primary-side flow passage Fp1 and an annular groove Ga are formed at one end of this insertion hole. Here, the inner diameter of the primary-side flow passage Fp1 is set slightly larger than the outer diameter of the expanded-diameter portion 11L of the main body 11. A secondary-side flow passage Fp2, which is formed in a direction perpendicular to the axial line L, is connected to the annular groove Ga. Furthermore, the insertion hole along the axial line L is formed with multiple annular steps whose diameter gradually decreases in a stepped manner from the annular groove Ga toward the other end. These multiple annular steps are formed, in order, with a first housing groove G1, a second housing groove G2, a third housing groove G3, and a fourth housing groove G4. Furthermore, an annular seal groove Gi is formed at the other end of the primary-side flow passage Fp1, in which an O-ring Or is accommodated. In addition, a female threaded engagement portion Bscf is formed on the inner circumferential surface of the second housing groove G2.

[0036] In the first embodiment, the shapes of the main body 11 and the piping block B as shown in Figure 2 were described, but this is only one example, and any shape is acceptable as long as the piping block B has an insertion hole and the main body 11 has an outer shape that can be inserted into this insertion hole.

[0037] <About installation> The installation of the pressure regulating valve 100a to the piping block B will now be described. The pressure regulating valve 100a is inserted into one end of the primary flow passage Fp1 along the axial direction L of the piping block B. Then, while threading the male threaded portion 11Scm of the body 11 into the female threaded portion Bscf of the piping block B, the body 11 is moved toward the other end in the axial direction L until the other end 11u of the body 11 abuts against the piping block B. In this installed state of the pressure regulating valve 100a, the primary flow passage Fp1 is communicated with the primary port 1A defined by the valve seat 12, and primary pressure P1 is introduced thereinto. Meanwhile, the secondary flow passage Fp2 is communicated with the secondary port 1B defined by the horizontal hole 11a of the body 11, and secondary pressure P2 is introduced thereinto. At this time, an O-ring Or is sandwiched between the enlarged diameter portion 11L of the body 11 and the annular seal groove Gi, sealing the gap between the body 11 and the piping block B. Furthermore, the crimped portion Cr of the bellows top cover 52 is accommodated in the fourth accommodation groove G4, and therefore interference with the piping block B is prevented.

[0038] <External forces acting on the valve disc in the valve opening direction> A high primary pressure P1 and a low secondary pressure P2 are introduced into the primary port 1A and secondary port 1B of the pressure regulating valve 100a, respectively. Hereinafter, the effective pressure-receiving surface of the pressure-sensing bellows 51 will be described using FIG. 4. Then, using the time-pressure characteristic diagram shown in FIG. 5(a) and the time-external force acting in the valve opening direction characteristic diagram shown in FIG. 5(b), the external forces F1, F2, and F3 acting in the valve opening direction of the valve disc 20 will be sequentially described in the following order: <State 1: State immediately after valve opening>, <State 2: State in which pressure changes immediately after valve opening>, and <State 3: State in which the valve disc is balanced after movement due to the pressure change>. While details will be described later, the external force F3(1) shown in FIG. 5(b) is the formula for F3 with the additional condition 1 (Sv > Sx) added. Here, the external force F3 acting in the valve opening direction of the valve disc 20 before the addition of condition 1 will be described.

[0039] <Effective pressure-receiving surface of pressure-sensing bellows> The effective pressure-receiving surface of the pressure-sensing bellows 51 will be described with reference to Fig. 4. Fig. 4 is a schematic diagram in which deformation in the pressure-sensing bellows 51 is exaggerated.

[0040] As shown in FIG. 4 , the effective pressure-receiving surface of the pressure-sensitive bellows 51 in the direction of the axis L is a ring-shaped deformation region Dr where the pressure-sensitive bellows 51 undergoes effective deformation when subjected to the secondary pressure P2. Here, the pressure-sensitive bellows 51 has an outer shape with peaks and valleys. When the secondary pressure P2 in the external space of the pressure-sensitive bellows 51 is greater than the internal pressure P0 of the pressure-sensitive bellows, the pressure-sensitive bellows 51 mainly deforms and contracts at the valley side, shortening its overall length. In other words, the pressure-sensitive bellows 51 only generates a substantial pressure load up to the constant ring-shaped deformation region Dr from the valley side to the peak side. This ring-shaped effective pressure-receiving surface is determined by calculation or testing. The outer peripheral diameter of the ring-shaped effective pressure-receiving surface is the effective pressure-receiving diameter Dx of the pressure-sensitive bellows 51, and the inner peripheral diameter of the ring-shaped effective pressure-receiving surface is the inner diameter Dy of the pressure-sensitive bellows 51. In addition, the ring-shaped effective pressure-receiving surface of the pressure-sensing bellows 51 remains unchanged whether the valve is in the open state or the closed state.

[0041] <State 1: Immediately after the valve is opened> In State 1, as shown in the time-pressure characteristic diagram of Figure 5(a), time t0 is the moment when the primary pressure P1 reaches the valve-open set pressure Pos. At this time, the relational expression for the external force F1 acting in the valve opening direction of the valve element 20, as shown in the time-external force acting in the valve opening direction characteristic diagram of Figure 5(b), can be expressed as follows: Note that, as shown in Figure 3, the sign on the right-hand side indicates the valve opening direction, with a positive sign. F1=Fa-Fb-Fc+Fd-Fk (Formula 1) Where, Fa = P1 x Sv: Force [N] acting on the valve body 20 by the primary pressure P1. Fb = P0 x Sw: Force [N] acting on the valve element 20 due to the internal pressure P0 of the pressure-sensing bellows Fc = P2 × (Sv - Sw): Force [N] acting on the valve element 20 due to the secondary pressure P2 Fd = P2 × (Sx - Sy): Force [N] acting on the effective pressure receiving surface of the pressure-sensing bellows 51 due to the secondary pressure P2 Fk = k × La: biasing force of the composite spring (pressure-sensing bellows 51 itself and adjusting spring 41) (k: spring constant of the composite spring (parallel arrangement), La: displacement amount from the natural length of the composite spring) [N] P0: Pressure-sensing bellows internal pressure [N / mm 2 ] P1: Primary pressure [N / mm 2 ] P2: Secondary pressure [N / mm 2 ] Sv: Pressure-receiving area [mm] calculated based on the diameter Dv of valve port 1A 2 ] Sw: Pressure-receiving area [mm] calculated based on the inner diameter Dw of the bowl portion 22 of the valve body 20 2 ] Sx: Area [mm] calculated based on the effective pressure-receiving diameter Dx of the pressure-sensing bellows 51 2 ] Sy: Area calculated based on the inner diameter Dy of the pressure-sensing bellows [mm 2 ] The pressure P0 inside the pressure-sensing bellows may be any of a pressure lower than atmospheric pressure, atmospheric pressure, and a pressure higher than atmospheric pressure.

[0042] Therefore, (Equation 1) can be rearranged into the following equation. F1=P1×Sv-P0×Sw-P2×(Sv-Sw)+P2×(Sx-Sy)-k×La (Formula 2)

[0043] 3, the inner diameter Dw of the bowl portion 22 of the valve disc 20 and the inner diameter Dy of the pressure-sensing bellows are substantially the same (Dw≈Dy). In other words, the pressure-receiving area Sw calculated based on the inner diameter Dw of the bowl portion 22 of the valve disc 20 and the area Sy calculated based on the inner diameter Dy of the pressure-sensing bellows are substantially the same (Sw≈Sy). Therefore, to make it easier to understand the relational expression of the external force F1 acting in the valve opening direction of the valve disc 20, Sw=Sy will be used.

[0044] Therefore, substituting Sw=Sy into (Equation 2), we get F1=P1×Sv+P2×(Sx-Sv)-P0×Sw-k×La (Formula 3)

[0045] Here, in state 1, the external force F1 acting on the valve element 20 in the valve opening direction is balanced in the direction of the axis L, and is therefore expressed as follows: F1=P1×Sv+P2×(Sx-Sv)-P0×Sw-k×La=0 (Formula 4)

[0046] <State 2: Pressure changes immediately after the valve is opened> In State 2, as shown in the time-pressure characteristic diagram of Figure 5(a), at time t0, from State 1, the primary pressure P1 drops (P1 → P1 - ΔP1) due to the outflow of fluid, and the secondary pressure P2 rises (P2 → P2 + ΔP2) due to the inflow of fluid, resulting in an imbalance in the external force F2 acting in the valve opening direction of the valve disc 20, as shown in the time-external force acting in the valve opening direction characteristic diagram of Figure 5(b). Here, ΔP1>0, ΔP2>0.

[0047] In this case, the relational expression of the external force F2 acting on the valve element 20 in the valve opening direction can be expressed as follows: F2=(P1-ΔP1)×Sv+(P2+ΔP2)×(Sx-Sv)-P0×Sw-k×La (Formula 5) Here, by substituting (Equation 4) into (Equation 5), the following equation can be obtained. F2=-ΔP1×Sv+ΔP2×(Sx-Sv) (Formula 6)

[0048] In State 2, the external force F2 acting on the valve element 20 in the valve opening direction is not balanced (F2≠0).

[0049] <State 3: Balanced state after valve disc movement due to pressure change> In State 3, as shown in the time-pressure characteristic diagram of Figure 5(a), at time t0, the movement of the valve disc 20 due to the pressure changes ΔP1 and ΔP2 in State 2 causes a balance between the external force F3 acting in the valve opening direction of the valve disc 20, as shown in the time-external force acting in the valve opening direction characteristic diagram of Figure 5(b). Specifically, in State 3, the pressure change in State 2 causes the valve disc 20 to move in the direction of the axis L, resulting in a change in the internal pressure P0 of the pressure-sensing bellows (P0 → P0 + ΔP0) and a change in the displacement La from the natural length (La → La + ΔLa).

[0050] Here, when the valve disc 20 moves in the valve opening direction, the change in the pressure P0 inside the pressure sensing bellows is an increase in pressure (ΔP0>0) because the internal space 51a of the pressure sensing bellows 51 decreases, while the change in the displacement La from the natural length of the pressure sensing bellows 51 itself and the adjusting spring 41 is an increase in displacement (ΔLa>0) because they are further compressed. Therefore, when the valve disc 20 moves in the valve opening direction, ΔP0>0 and ΔLa>0 hold.

[0051] Furthermore, when the valve disc 20 moves in the valve closing direction, the change in the pressure P0 inside the pressure sensing bellows is a decrease in pressure (ΔP0<0) because the internal space 51a of the pressure sensing bellows 51 increases, while the change in the displacement La from the natural length of the pressure sensing bellows 51 itself and the adjusting spring 41 is a decrease in displacement (ΔLa<0) because they are displaced to their natural lengths. Therefore, when the valve disc 20 moves in the valve closing direction, ΔP0<0 and ΔLa<0 hold.

[0052] In this state 3, the relational expression of the external force F3 acting in the valve opening direction of the valve body 20 can be expressed as follows in (Equation 5), where the change in the internal pressure P0 of the pressure-sensing bellows (P0 → P0 + ΔP0) and the change in displacement La from the natural length (La → La + ΔLa) occur: F3=(P1-ΔP1)×Sv+(P2+ΔP2)×(Sx-Sv)-(P0+ΔP0)×Sw-k×(La+ΔLa) (Formula 7)

[0053] Here, by substituting (Equation 4) into (Equation 7), the following equation can be obtained. F3=-ΔP1×Sv+ΔP2×(Sx-Sv)-ΔP0×Sw-k×ΔLa (Formula 8)

[0054] Furthermore, in state 3, the external force F3 acting in the valve opening direction of the valve element 20 is balanced in the direction of the axis L, and is therefore expressed as follows: F3=-ΔP1×Sv+ΔP2×(Sx-Sv)-ΔP0×Sw-k×ΔLa=0 (Formula 9)

[0055] <About the mechanism of hunting in pressure control valves> 5(a) and 5(b), the external forces F1, F2, and F3 acting on the valve disc 20 in the valve opening direction have been described for States 1 to 3. In the pressure regulating valve 100a, hunting occurs due to the relationship in magnitude between the pressure-receiving area Sv calculated based on the diameter Dv of the valve port 1A and the effective pressure-receiving diametric area Sx of the pressure-sensing bellows 51 (for example, condition 1 (Sv > Sx) or condition 2 (Sv = Sx)). Hunting refers to the phenomenon in which the valve disc 20 seats and unseats on the valve seat 12a within a short period of time, repeatedly switching between a valve-closed state and a valve-open state.

[0056] Here, the mechanism of occurrence of hunting in the pressure regulating valve 100a will be explained in order for condition 1 (Sv>Sx) and condition 2 (Sv=Sx).

[0057] <Condition 1 (Sv>Sx)> Assuming that condition 1 (Sv>Sx) is true in state 3, we will consider the external force F3(1) acting in the valve opening direction of the valve disc 20 using Figures 5(a) and (b). This will explain the mechanism by which hunting occurs.

[0058] The external force F3(1) acting on the valve element 20 in the valve opening direction is expressed as follows based on (Equation 9). F3(1)=-ΔP1×Sv+ΔP2×(Sx-Sv)-ΔP0×Sw-k×ΔLa=0 (Formula 10)

[0059] Under condition 1 (Sv>Sx), ΔP2×(Sx-Sv) in (Equation 10) is a negative value. Therefore, in (Equation 10), -ΔP1×Sv+ΔP2×(Sx-Sv) is a negative value, while -ΔP0×Sw-k×ΔLa is a positive value (i.e., ΔP0<0 and ΔLa<0).

[0060] Therefore, under condition 1 (Sv>Sx), ΔP0<0 and ΔLa<0 hold, and the valve disc 20 moves in the valve closing direction, as described above. As a result, as shown in Figure 5(a), the moment the valve is closed, it again opens, and the changes between state 1, state 2, and state 3 are repeated, so the conventional problem (frequent hunting occurring immediately after the valve is opened) remains.

[0061] <Condition 2 (Sv = Sx)> Assuming that condition 2 (Sv = Sx) is met in state 3, we will consider the external force F3(2) acting in the valve opening direction of the valve disc 20 using Figures 5(c) and (d). This will explain the mechanism by which hunting occurs.

[0062] The external force F3(2) acting on the valve element 20 in the valve opening direction is expressed as follows based on (Equation 9). F3(2)=-ΔP1×Sv+ΔP2×(Sx-Sv)-ΔP0×Sw-k×ΔLa=0 (Formula 11)

[0063] Under condition 2 (Sv=Sx), ΔP2×(Sx−Sv) in (Equation 11) is 0. Therefore, (Equation 11) can be rearranged into the following equation. F3(2)=-ΔP1×Sv-ΔP0×Sw-k×ΔLa=0 (Formula 12)

[0064] Here, −ΔP1×Sv is a negative value, while −ΔP0×Sw-k×ΔLa is a positive value (that is, ΔP0<0 and ΔLa<0).

[0065] Therefore, under condition 2 (Sv=Sx), ΔP0<0 and ΔLa<0 hold, as in condition 1 (Sv>Sx), and the valve disc 20 moves in the valve closing direction. As a result, as shown in Figure 5(c), the moment the valve is closed, it again opens, and the changes between state 1, state 2, and state 3 are repeated, causing frequent hunting immediately after the valve is opened.

[0066] Incidentally, the external force F3(2) (see Equation (12)) acting in the valve opening direction of the valve element 20 under Condition 2 (Sv = Sx) is a negative value and does not include ΔP2×(Sx - Sv). Therefore, it is slightly larger than the external force F3(1) (see Equation (10)) acting in the valve opening direction of the valve element 20 under Condition 1 (Sv > Sx). As a result, as shown in FIGS. 5(a) and 5(c), although the period of hunting under Condition 2 (Sv = Sx) is slightly longer than that under Condition 1 (Sv > Sx), it still has the conventional problem (high-frequency hunting occurs immediately after valve opening).

[0067] <Hunting Frequency Reduction Means (1) (Condition 3 (Sv < Sx))> From here, in the pressure regulating valve 100a, Condition 3 (Sv < Sx), which is a means for reducing the hunting frequency of the valve element 20 with respect to the valve seat 12a, will be described.

[0068] <Regarding Condition 3 (Sv < Sx)> Assuming that Condition 3 (Sv < Sx) is in State 3, the external force F3(3) acting in the valve opening direction of the valve element 20 will be considered using FIGS. 6(a) to 6(d). Thereby, the hunting frequency reduction means (1) will be described. Although details will be described later, the external force F3(3) acting in the valve opening direction of the valve element 20 includes the external forces F3(3-1) and F3(3-2) acting in the valve opening direction of the valve element 20, respectively.

[0069] The external force F3(3) acting in the valve opening direction of the valve element 20 is expressed as follows based on Equation (9). F3(3)=-ΔP1×Sv+ΔP II ×(Sx - Sv)-ΔP0×Sw - k×ΔLa = 0 (Equation (13))

[0070] Under Condition 3 (Sv < Sx), the positive or negative of -ΔP0×Sw - k×ΔLa in Equation (13) is opposite to the positive or negative of -ΔP1×Sv+ΔP II ×(Sx - Sv). Therefore, hereinafter, Condition 3 (Sv < Sx) will be further classified and considered for the cases of Condition 3-1 (-ΔP1×Sv+ΔP II ×(Sx - Sv) < 0) and Condition 3-2 (-ΔP1×Sv+ΔP II ×(Sx - Sv) ≥ 0), respectively.

[0071] Note that the condition 3-1, -ΔP1×Sv + ΔP2×(Sx - Sv) < 0, can be rearranged as ΔP2 / ΔP1 < Sv / (Sx - Sv), and the condition 3-2, -ΔP1×Sv + ΔP2×(Sx - Sv) ≥ 0, can be rearranged as ΔP2 / ΔP1 ≥ Sv / (Sx - Sv). Therefore, whether either condition 3-1 or condition 3-2 can be satisfied is determined by the magnitude relationship between ΔP2 / ΔP1 and Sv / (Sx - Sv) (a predetermined value).

[0072] <Regarding condition 3-1 (-ΔP1×Sv + ΔP2×(Sx - Sv) < 0)> First, assuming the state 3 satisfies condition 3 (Sv < Sx) and condition 3-1 (-ΔP1×Sv + ΔP2×(Sx - Sv) < 0), the external force F3(3-1) acting in the valve opening direction of the valve body 20 is considered using FIGS. 6(a) and (b). Thereby, the hunting frequency reduction means (1) is explained.

[0073] The external force F3(3-1) acting in the valve opening direction of the valve body 20 is expressed as follows based on (Equation 13). F3(3-1)=-ΔP1×Sv + ΔP2×(Sx - Sv)-ΔP0×Sw - k×ΔLa = 0 (Equation 14) In condition 3-1, since -ΔP1×Sv + ΔP2×(Sx - Sv) < 0 is satisfied, -ΔP0×Sw - k×ΔLa becomes a positive value with the opposite sign (that is, ΔP0 < 0 and ΔLa < 0).

[0074] Therefore, in condition 3-1, similar to condition 1 (Sv > Sx) and condition 2 (Sv = Sx), the valve body 20 moves in the valve closing direction. As a result, as shown in FIG. 6(a), at the moment when the valve is in the closed state, it becomes the open state again, and the changes among state 1, state 2, and state 3 are repeated.

[0075] However, in F3(3-1) of condition 3-1 (refer to formula 14), compared with F3(1) of condition 1 (Sv > Sx) (refer to formula 10) and F3(2) of condition 2 (Sv = Sx) (refer to formula 12), since ΔP2×(Sx - Sv) > 0 is added, as shown in FIGS. 5(b), 5(d), and 6(b), F3(3-1) of condition 3-1 becomes a larger value compared with F3(1) of condition 1 and F3(2) of condition 2. As a result, in condition 3-1, as shown in FIG. 6(b), the decrease amount of the external force F acting in the valve opening direction of the valve body 20 at time t0 can be made extremely small. Therefore, compared with condition 1 (Sv > Sx) and condition 2 (Sv = Sx), the hunting period shown in FIG. 6(a) can be made longer. As a result, in condition 3-1, the conventional problem (high-frequency hunting occurs immediately after valve opening) can be solved, and high responsiveness to minute pressure changes can be surely maintained.

[0076] <Regarding condition 3-2 (-ΔP1×Sv + ΔP2×(Sx - Sv) ≥ 0)> Next, as state 3, assuming condition 3 (Sv < Sx) and condition 3-2 (-ΔP1×Sv + ΔP2×(Sx - Sv) ≥ 0), the external force F3(3-2) acting in the valve opening direction of the valve body 20 is considered using FIGS. 6(c) and (d). Thereby, the hunting frequency reduction means (1) is explained.

[0077] The external force F3(3-2) acting in the valve opening direction of the valve body 20 is expressed as follows based on (formula 13). F3(3-2)=-ΔP1×Sv + ΔP2×(Sx - Sv)-ΔP0×Sw - k×ΔLa = 0 (formula 15) In condition 3-2, since -ΔP1×Sv + ΔP2×(Sx - Sv) ≥ 0 is satisfied, -ΔP0×Sw - k×ΔLa becomes a negative value with the opposite sign (that is, ΔP0 > 0 and ΔLa > 0).

[0078] Therefore, in Condition 3-2, unlike Condition 1 (Sv > Sx), Condition 2 (Sv = Sx), and Condition 3-1, the valve body 20 moves in the valve opening direction and maintains the valve open state. As a result, as shown in FIG. 6(c), hunting of the valve body 20 with respect to the valve seat 12a can be completely eliminated. Here, when the other end of the cylinder member 31 abuts against one end of the connecting member 32 that functions as a stopper, the valve body 20 reaches the fully open state. As a result, in Condition 3-2, the conventional problem (high-frequency hunting immediately after valve opening) is solved, and high responsiveness to minute pressure changes can be surely maintained.

[0079] In Condition 3 of the first embodiment, the effective pressure receiving diameter area Sx of the pressure-sensitive bellows 51 is set to be larger than the pressure receiving area Sv calculated based on the diameter Dv of the valve port 1A. That is, the effective pressure receiving diameter Dx of the pressure-sensitive bellows 51 is set to be larger than the diameter Dv of the valve port 1A. Specifically, the ratio of the effective pressure receiving diameter area Sx of the pressure-sensitive bellows 51 to the pressure receiving area Sv calculated based on the diameter Dv of the valve port 1A is set to be greater than 1 and less than or equal to 1.2 (1 < Sx / Sv ≤ 1.2). That is, the ratio of the effective pressure receiving diameter Dx of the pressure-sensitive bellows 51 to the diameter Dv of the valve port 1A is set to be greater than 1 and less than or equal to 1.1 (1 < Dx / Dv ≤ 1.1).

[0080] <Regarding the concern (high inventory management cost due to individual differences in pressure-sensitive bellows)> The bellows 51 for pressure sensing is manufactured by a forming method (such as roll forming method, press forming method, hydraulic forming method, etc.) with relatively large variations in processing tolerances. Therefore, there are large variations in the effective pressure-receiving diameter area Sx of the bellows 51 for pressure sensing. For this reason, in order to satisfy Condition 3, the effective pressure-receiving diameter area Sx of the bellows 51 for pressure sensing should be larger than the pressure-receiving area Sv calculated based on the diameter Dv of the valve port 1A. That is, it is necessary to select the bellows 51 for pressure sensing so that the effective pressure-receiving diameter Dx of the bellows 51 for pressure sensing is larger than the diameter Dv of the valve port 1A. At this time, since the individual differences of the bellows 51 for pressure sensing are relatively large, there was a concern that the inventory of the bellows 51 for pressure sensing that does not satisfy Condition 3 would accumulate, increasing the inventory management cost (hereinafter referred to as "concern (high inventory management cost due to individual differences of the bellows for pressure sensing)").

[0081] On the other hand, in the first embodiment, as shown in FIG. 1, after separating the main body 11 and the valve seat portion 12, the relative position in the axial direction L of the main body 11 and the valve seat portion 12 is adjusted through the adjustment screw portion 42, which is a position adjustment portion. By adopting such a structure, the adjustment spring 41 and the bellows 5 for pressure sensing are expanded and contracted to adjust the biasing force on the valve body 20. Thus, in the first embodiment, by adopting a position adjustment portion that separates the main body 11 and the valve seat portion 12, based on the effective pressure-receiving diameter Dx of the bellows 51 for pressure sensing having individual differences, and selecting the valve seat portion 12 having the diameter Dv of the valve port 1A that satisfies Condition 3 (Dv < Dx (that is, Sv < Sx)), the concern (high inventory management cost due to individual differences of the bellows for pressure sensing) can be eliminated.

[0082] [[ID=⑧]]<Regarding the concern (hunting due to small change amount in the valve opening direction)> In the aforementioned Condition 3-2 (-ΔP1×Sv + ΔP2×(Sx - Sv) ≧ 0), (Equation 15) can be further arranged into the following equation.[[ID=①①]] ΔP0×Sw + k×ΔLa = -ΔP1×Sv + ΔP2×(Sx - Sv) ≧ 0 (Equation 16)

[0083] [[ID=①⑤]] According to this (Equation 16), the pressure change ΔP0 in the pressure sensing bellows internal pressure P0 and the amount of change ΔLa in the displacement La from the natural length of the pressure sensing bellows 51 itself and the adjusting spring 41 are inversely proportional, and therefore the amount of change ΔLa decreases as the pressure change ΔP0 increases. Therefore, under condition 3-2, when the amount of change ΔLa is small (i.e., the pressure change ΔP0 is large), there is a concern that hunting may occur due to a strong external impact or vibration being applied to the pressure adjustment valve 100a (hereinafter referred to as "concern (hunting due to small amount of change in the valve opening direction)").

[0084] <Means for reducing hunting frequency (2) (constant communication between the cylinder internal space and the sealed space)> In contrast, in the first embodiment, the hunting frequency reduction means (2) reduces the pressure change ΔP0 in the pressure-sensing bellows internal pressure P0 in order to increase the amount of change ΔLa in the displacement La from the natural length of the pressure-sensing bellows 51 itself and the adjusting spring 41. Specifically, as shown in FIGS. 1 to 3, the hunting frequency reduction means (2) is configured to constantly communicate the cylinder internal space 31a defined by the cylinder member 31, the piston member 33, and the valve body 20 with the internal space 51a of the pressure-sensing bellows 51 via a communication hole 31b formed in the cylinder member 31. By employing this hunting frequency reduction means (2), the volume of the internal space 51a of the pressure-sensing bellows 51 increases due to the addition of the cylinder internal space 31a, while the pressure change ΔP0 in the pressure-sensing bellows internal pressure P0 decreases. As a result, the change ΔLa in the displacement La from the natural length of the pressure-sensing bellows 51 itself and the adjusting spring 41 increases, so that the concern (hunting due to a small change in the valve opening direction) can be resolved.

[0085] As described above, in the pressure regulating valve 100a of the first embodiment, the hunting frequency reduction means (1) is achieved by setting the effective pressure-receiving diameter Dx of the pressure-sensing bellows 51 to be larger than the diameter Dv of the valve port 1A (Dx>Dv), thereby eliminating the conventional problem (high-frequency hunting occurring immediately after the valve is opened) and reliably maintaining high responsiveness to minute pressure changes.

[0086] Furthermore, in the pressure regulating valve 100a of the first embodiment, the main body 11 and the valve seat 12 are separate bodies, and the relative positions of the main body 11 and the valve seat 12 in the direction of the axis L are adjusted via the adjusting screw 42, which is a position adjusting part, thereby eliminating the concern (high inventory management costs due to individual differences in the pressure-sensing bellows). Furthermore, in the pressure regulating valve 100a of the first embodiment, the cylinder internal space 31a is constantly communicated with the internal space 51a of the pressure-sensing bellows 51 via the communicating hole 31b as a hunting frequency reducing means (2), thereby eliminating the concern (hunting due to a small amount of change in the valve opening direction).

[0087] (Second embodiment) A pressure regulating valve 100b according to the second embodiment will be described with reference to Figures 7 and 8. Note that the pressure regulating valve 100b according to the second embodiment differs in overall configuration from the pressure regulating valve 100a according to the first embodiment, but like the pressure regulating valve 100a according to the first embodiment, it has a valve element 20', an adjusting spring unit 40', and a pressure-sensing bellows unit 50', and also has relational expressions (Equation 1') to (Equation 9') and (Equation 13') to (Equation 16') for the external force F' acting in the valve opening direction of the valve element 20'. Here, since (Equation 1') to (Equation 9') and (Equation 13') to (Equation 16') in the second embodiment are similar to (Equation 1) to (Equation 9) and (Equation 13) to (Equation 16) in the first embodiment, a description of the derivation process will be omitted here.

[0088] <Configuration of pressure regulating valve> A pressure regulating valve 100b according to a second embodiment of the present invention will be described using Figure 7. The pressure regulating valve 100b is mainly composed of a valve body 10', a valve element 20', an adjusting spring unit 40', a pressure-sensing bellows unit 50', and first and second centripetal means 70, 80. Each component of the pressure regulating valve 100b will be described in order below. Note that a high primary pressure P1 is introduced into the primary port 1A, while a low secondary pressure P2 is introduced into the secondary port 1B.

[0089] As will be described in detail later, the pressure regulating valve 100b of the second embodiment, like the first embodiment, has a hunting frequency reduction means (1) in which the effective pressure-receiving diameter Dx' of the pressure-sensing bellows 51' is set to be larger than the diameter Dv' of the valve port 11f' (Dx' > Dv'), thereby eliminating the conventional problem (high-frequency hunting occurring immediately after the valve is opened) and reliably maintaining high responsiveness to minute pressure changes.

[0090] The valve body 10' is composed of a main body 11' connected to the inlet pipe 1 and the outlet pipe 2, a connecting member 13' that is press-fitted into the other end of the main body 11' and then brazed to join, and a spring case 14' that is joined to the other end of the connecting member 13' by crimping or the like. The valve body 10' is made of metal such as brass, iron, aluminum, stainless steel, etc.

[0091] The main body 11' is a hollow cylindrical member having a through-hole that penetrates along the axis L. This through-hole is provided with a primary side port 1A connected to the inlet pipe 1, a valve element guide hole 11e', a valve port 11f', a valve chamber 11j', and a storage chamber A that are all in communication with each other. The valve element guide hole 11e' has a smaller inner diameter than the valve port 11f', and an annular step 11g' is provided at the connection between the valve element guide hole 11e' and the valve port 11f'. The valve chamber 11j' has a larger inner diameter than the valve port 11f', and an annular valve seat 11h' is provided at the connection between the valve chamber 11j' and the valve port 11f'.

[0092] The main body 11' further has a through-hole that penetrates radially from the valve chamber 11j', and this through-hole is provided with a secondary-side port 1B that connects to the outflow pipe 2. This allows secondary-side pressure P2 to be introduced into the valve chamber 11j' and the storage chamber A via the secondary-side port 1B when the valve is closed.

[0093] The connecting member 13' is a hollow cylindrical member having a through hole that penetrates along the axis L, and has approximately the same inner diameter as the storage chamber A and is provided with an opening 13a' that is continuously connected to the storage chamber A.

[0094] The spring case 14' is a hollow cylindrical member having a through hole that penetrates along the axis L, and is provided with a spring accommodating chamber 14a'. A female threaded portion 42a' is provided on the inner peripheral side of the other end of the spring case 14', and is threadedly engaged with a male threaded portion 42b' that is provided on the outer peripheral side of the adjustment screw portion 42' so as to be movable in the direction of the axis L. A thread gap is formed between the female threaded portion 42a' and the male threaded portion 42b', and the spring accommodating chamber 14a' is always in communication with the atmosphere via this thread gap.

[0095] The valve element 20' comprises a valve portion 21' having a generally truncated cone shape provided at the other end in the direction of the axis L, a cylindrical guide portion 22' extending toward one end, and an annular spring support portion 23' provided between the valve portion 21 and the guide portion 22'. The valve element 20' also has an internal flow path 24' that extends through the guide portion 22' along the axis L and penetrates the valve portion 21' in the radial direction. The valve element 20' is made of a metal such as stainless steel.

[0096] The guide portion 22' of the valve element 20' is arranged so as to be able to guide the valve element guide hole 11e' of the main body 11' in the direction of the axis L. The valve element 20' is constantly biased in the valve opening direction by the valve spring 6 sandwiched between the spring support portion 23' of the valve element 20' and the step portion 11g' of the main body 11'.

[0097] The adjustment spring unit 40' is composed of an adjustment spring 41' (biasing means) that biases the valve disc 20' in the valve closing direction, and an adjustment screw 42' (position adjustment part) and a spring receiving member 43' that hold the adjustment spring 41'. The adjustment spring unit 40' is made of metal such as brass, iron, aluminum, or stainless steel, and is housed in a spring accommodating chamber 14a' of a spring case 14'. A male threaded portion 42b' provided on the outer periphery of the adjustment screw 42' is threadedly engaged with a female threaded portion 42a' provided on the inner periphery of the other end of the spring case 14', and the biasing force of the adjustment spring 41' can be adjusted by moving the adjustment screw 42' in the direction of the axis L.

[0098] The pressure-sensing bellows unit 50' is composed of a pressure-sensing bellows 51' (biasing means), a bellows upper cover 52' ​​(slide unit), a bellows lower cover 53', and a connecting rod 54' (slide unit). One end and the other end of the pressure-sensing bellows 51' extending along the axis L are brought into close contact with the bellows upper cover 52' ​​and the bellows lower cover 53', respectively, and the pressure-sensing bellows 51' biases the valve body 20' in the valve closing direction. The connecting rod 54' also has one end and the other end extending along the axis L engaged with the bellows upper cover 52' ​​and the bellows lower cover 53', respectively. The pressure-sensing bellows unit 50' is made of a metal such as stainless steel, and is housed in the accommodation chamber A of the main body 11' and the opening 13a' of the connecting member 13'.

[0099] The pressure-sensing bellows 51' is in close contact with the bellows upper cover 52' ​​and the bellows lower cover 53', so that secondary pressure P2 is always introduced into the space outside the pressure-sensing bellows 51' via the valve chamber 11j' and the accommodation chamber A. The pressure-sensing bellows 51' is set so as to always be out of contact with the main body 11' and the connecting rod 54'.

[0100] 8, the effective pressure-receiving diameter Dx' of the pressure-sensing bellows 51' in the second embodiment is set larger than the diameter Dv' of the valve port 11f' (Dx'>Dv'), as in the first embodiment, and therefore the conventional problem (frequent hunting occurring immediately after the valve is opened) can be resolved. Note that, as in the first embodiment, the effective pressure-receiving diameter Dx' of the pressure-sensing bellows 51' indicates the deformation region in which deformation in the direction of the axis L effectively occurs in the pressure-sensing bellows 51', i.e., the outer circumferential diameter of the ring-shaped effective pressure-receiving surface, and is determined by calculation or testing.

[0101] The connecting rod 54' includes a generally cylindrical large-diameter portion 54a' extending toward one end in the direction of the axis L, and a generally cylindrical small-diameter portion 54b' extending from the large-diameter portion 54a' toward the other end in the direction of the axis L. A recess 54ar' is formed at one end of the large-diameter portion 54a'. Furthermore, an annular step 54c' is formed at the joint between the large-diameter portion 54a' and the small-diameter portion 54b'.

[0102] The bellows top cover 52' ​​has a communication hole 52a' extending concentrically along the axis L, and a bellows top cover joint 52b' into which the other end of the pressure-sensing bellows 51' is inserted and tightly attached. A small-diameter portion 54b' of a connecting rod 54' is arranged in this communication hole 52a' so as to be insertable in the direction of the axis L. Here, the pressure-sensing bellows unit 50' is fixed to the valve body 10' via a welded portion W. A gap Gp is ​​formed between the small-diameter portion 54b' of the connecting rod 54' and the communication hole 52a' of the bellows top cover 52'.

[0103] Here, as will be described in detail later, the pressure regulating valve 100b of the second embodiment has a hunting frequency reducing means (2') in which the internal space of the pressure sensing bellows 51' is constantly in communication with the atmosphere via this gap Gp and the thread gap of the adjusting screw portion 42', thereby making it possible to make the pressure change ΔP0 in the pressure inside the pressure sensing bellows P0 zero. As a result, the amount of change ΔLa' in the displacement La' from the natural length of the pressure sensing bellows 51' itself and the adjusting spring 41' can be made relatively large, thereby eliminating the concern (hunting due to a small amount of change in the valve opening direction).

[0104] The bellows bottom cover 53' has a protrusion 53a' extending toward the other end and a bellows bottom cover joint 53b' into which one end of the pressure-sensing bellows 51' is inserted and tightly fitted. The protrusion 53a' is loosely fitted into the recess 54ar' so as to be movable in the radial direction.

[0105] The first centring means 70 is composed of a pair of conical first upper and lower recesses 71, 72 formed on axially opposing surfaces on the upper end surface of the valve portion 21' and the lower end surface of the bellows bottom cover 53', and a first ball 73 sandwiched between the pair of first upper and lower recesses 71, 72. This conical shape has a bottom surface formed concentrically with the axis L and an apex located on the axis L. This first ball 73 is made of a metal such as stainless steel.

[0106] Similarly, the second centring means 80 is made up of a pair of conical second upper-end recesses 81 and second lower-end recesses 82 formed on axially opposing surfaces of the upper end surface of the connecting rod 54' and the lower end surface of the spring receiving member 43', and a second ball 83 held between the pair of second upper-end recesses 81 and second lower-end recesses 82. This conical shape has a bottom surface formed concentrically with the axis L and an apex located on the axis L. This second ball 83 is made of metal such as stainless steel.

[0107] <External forces acting on the valve disc in the valve opening direction> A high primary pressure P1 and a low secondary pressure P2 are introduced into the primary port 1A and secondary port 1B of the pressure regulating valve 100b, respectively. Hereinafter, with reference to FIG. 8, the external forces F1', F2', and F3' acting in the valve opening direction of the valve disc 20' will be described in order in <State 1: State immediately after the valve is opened>, <State 2: State after pressure change immediately after the valve is opened>, and <State 3: State in equilibrium after the valve disc moves due to the pressure change>. For simplicity's sake, when examining the relational expression for the external force F' acting in the valve opening direction of the valve disc 20', the valve disc 20', first ball 73, and bellows bottom cover 53' will be treated as being integrally formed. Furthermore, as will be described in detail later, the relational equation for the external force F' acting in the valve opening direction of the valve body 20' in the second embodiment is the same as the relational equation for the external force F acting in the valve opening direction of the valve body 20 in the first embodiment, and therefore the only difference is the dashes added to Sv, Sw, Sx, Sy, k, La, and ΔLa.

[0108] <State 1: Immediately after the valve is opened> In State 1, similarly to the first embodiment, the relational expression of the external force F1' acting in the valve opening direction of the valve element 20' can be expressed as follows: Note that the sign on the right side is positive in the valve opening direction. F1'=Fa'-Fb'-Fc'+Fd'-Fk' (Formula 1') Where, Fa'=P1×Sv': Force [N] acting on the valve body 20' by the primary pressure P1. Fb' = P0 x Sw': Force [N] acting on the valve element 20' due to the internal pressure P0 of the pressure-sensing bellows Fc' = P2 × (Sv' - Sw'): Force [N] acting on the valve element 20' due to the secondary pressure P2 Fd' = P2 x (Sx' - Sy'): Force [N] acting on the effective pressure-receiving surface of the pressure-sensing bellows 51' by the secondary pressure P2 Fk' = k' x La': biasing force of the composite spring (pressure-sensing bellows 51' itself and adjusting spring 41') (k': spring constant of the composite spring (arranged in series), La': displacement of the composite spring from its natural length) [N] P0: Pressure-sensing bellows internal pressure [N / mm 2 ] P1: Primary pressure [N / mm 2 ] P2: Secondary pressure [N / mm 2 ] Sv': Pressure-receiving area [mm] calculated based on the diameter Dv' of valve port 11f' 2 ] Sw': Pressure-receiving area [mm ] calculated based on the inner diameter Dw' of the contact area between the bellows lower cover 53' considered to be integral with the valve body 20' and the pressure-sensing bellows 51' 2 ] Sx': Area [mm ] calculated based on the effective pressure-receiving diameter Dx' of the pressure-sensing bellows 51' 2 ] Sy': Area calculated based on the pressure-sensing bellows inner diameter Dy' [mm 2 ] The internal pressure P0 of the pressure-sensing bellows is always atmospheric pressure.

[0109] Therefore, (Equation 1') can be rearranged into the following equation. F1'=P1×Sv'-P0×Sw'-P2×(Sv'-Sw')+P2×(Sx'-Sy')-k'×La' (Formula 2')

[0110] 8, the inner diameter Dw' of the contact area between the bellows bottom cover 53' and the pressure-sensing bellows 51' and the inner diameter Dy' of the pressure-sensing bellows are substantially the same (Dw' ≒ Dy'). In other words, the pressure-receiving area Sw' calculated based on the contact area inner diameter Dw' and the area Sy' calculated based on the pressure-sensing bellows inner diameter Dy' are substantially the same (Sw' ≒ Sy'). Therefore, to make it easier to understand the relational expression of the external force F1' acting in the valve-opening direction of the valve disc 20', Sw' = Sy' will be used.

[0111] Therefore, substituting Sw'=Sy' into (Equation 2'), we get F1'=P1×Sv'+P2×(Sx'-Sv')-P0×Sw'-k'×La' (Formula 3')

[0112] Here, in state 1, the external force F1' acting on the valve disc 20' in the valve opening direction is balanced in the axial direction L, and is therefore expressed as follows: F1'=P1×Sv'+P2×(Sx'-Sv')-P0×Sw'-k'×La'=0 (Formula 4')

[0113] Hereinafter, the relational expression of the external force F' acting in the valve opening direction of the valve disc 20' in the second embodiment is similar to the external force F acting in the valve opening direction of the valve disc 20 in the first embodiment, and therefore the explanation of the derivation process will be omitted here. Therefore, (Equation 4') to (Equation 9') and (Equation 13') to (Equation 16') in the second embodiment correspond to Sv, Sw, Sx, Sy, k, La, and ΔLa in (Equation 4) to (Equation 9) and (Equation 13) to (Equation 16) in the first embodiment with a prime added.

[0114] <State 2: Pressure changes immediately after the valve is opened> In State 2, similarly to the first embodiment, the relational expression of the external force F2' acting in the valve opening direction of the valve element 20' is an unbalanced state (F2'≠0), and is expressed as follows: F2'=-ΔP1×Sv'+ΔP2×(Sx'-Sv') (Equation 6')

[0115] <State 3: Balanced state after valve disc movement due to pressure change> In state 3, similar to the first embodiment, since the external force F3' acting in the valve opening direction of the valve element 20' balances in the direction of the axis L, it is expressed as follows. F3’=-ΔP1×Sv’+ΔP2×(Sx’-Sv’)-ΔP0×Sw’-k’×ΔLa’=0 (Equation 9’)

[0116] <Regarding the hunting frequency reduction means (1) (Condition 3 (Sv’ < Sx’))> Hereinafter, in the pressure regulating valve 100b, the condition 3 (Sv’ < Sx’), which is a means for reducing the hunting frequency of the valve element 20' with respect to the valve seat 11h’, will be described.

[0117] <Regarding Condition 3 (Sv’ < Sx’)> In Condition 3, similar to the first embodiment, the external force F3'(3) acting in the valve opening direction of the valve element 20' is expressed as follows based on (Equation 9’). F3’(3)=-ΔP1×Sv’+ΔP2×(Sx’-Sv’)-ΔP0×Sw’-k’×ΔLa’=0 (Equation 13’)

[0118] <Regarding Condition 3-1 (-ΔP1×Sv’+ΔP2×(Sx’-Sv’) < 0)> In Condition 3-1, similar to the first embodiment, the external force F3'(3-1) acting in the valve opening direction of the valve element 20' is expressed as follows based on (Equation 13’). F3’(3-1)=-ΔP1×Sv’+ΔP2×(Sx’-Sv’)-ΔP0×Sw’-k’×ΔLa’=0 (Equation 14’)

[0119] Therefore, in Condition 3-1, similar to the first embodiment, when the valve element 20' moves due to the pressure change immediately after valve opening, the decrease amount of the external force F3'(3-1) acting in the valve opening direction of the valve element 20' is made extremely small (see Fig. 6(b)), and the hunting period can be made even longer (see Fig. 6(a)), so the hunting frequency can be reduced. As a result, in Condition 3-1, the conventional problem (high-frequency hunting occurs immediately after valve opening) is solved, and high responsiveness to minute pressure changes can be surely maintained.

[0120] <Regarding condition 3-2 (-ΔP1×Sv’ + ΔP2×(Sx’ - Sv’) ≥ 0)> In condition 3-2, similar to the first embodiment, the external force F3’(3-2) acting in the valve opening direction of the valve body 20’ is expressed as follows based on (Equation 13’). F3’(3-2) = -ΔP1×Sv’ + ΔP2×(Sx’ - Sv’) - ΔP0×Sw’ - k’×ΔLa’ = zero (Equation 15’)

[0121] Therefore, in condition 3-2, similar to the first embodiment, when the valve body 20’ moves due to the pressure change immediately after valve opening, the valve body 20’ moves in the valve opening direction and maintains the valve open state, so hunting itself can be completely eliminated (see FIGS. 6(c) and (d)). Here, as shown in FIG. 7, when the stepped portion 54c’ of the connecting rod 54’ abuts against the bellows upper lid 52’ that functions as a stopper, the valve body 20’ reaches the fully open state. As a result, in condition 3-2, the conventional problem (high-frequency hunting occurs immediately after valve opening) can be solved, and high responsiveness to minute pressure changes can be surely maintained.<0​​​​​​​Under condition 3-2, as in the first embodiment, (Equation 15') can be further rearranged into the following equation. ΔP0×Sw'+k'×ΔLa'=-ΔP1×Sv'+ΔP2×(Sx'-Sv')≧0 (Equation 16')

[0124] Therefore, in condition 3-2, as in the first embodiment, when the change amount ΔLa' is small (i.e., the pressure change ΔP0 is large), there is a concern (hunting due to a small change amount in the valve opening direction) if the pressure regulating valve 100b is subjected to strong external impacts, vibrations, etc.

[0125] Here, in the first embodiment, the volume of the internal space 51a of the pressure-sensing bellows 51 shown in FIG. 3 is increased to reduce the pressure change ΔP0 of the internal pressure P0 of the pressure-sensing bellows, thereby eliminating the concern (hunting due to a small amount of change in the valve opening direction).

[0126] However, in the first embodiment, the internal space 51a of the pressure-sensing bellows 51 is a sealed space, and therefore the influence of the pressure change ΔP0 of the internal pressure P0 of the pressure-sensing bellows cannot be completely suppressed.

[0127] <Means for reducing hunting frequency (2') (keeping the internal space of the pressure-sensing bellows constantly connected to the atmosphere)> 7, in the second embodiment, the hunting frequency reduction means (2') is configured to constantly connect the internal space 51a' of the pressure-sensing bellows 51' to the atmosphere via a gap Gp formed between the small-diameter portion 54b' of the connecting rod 54' and the communication hole 52a' of the bellows top cover 52' ​​and a thread gap of the adjusting screw portion 42', thereby reducing the pressure change ΔP0 in the pressure inside the pressure-sensing bellows P0 to zero. By employing this hunting frequency reduction means (2'), the influence of the pressure change ΔP0 in the pressure inside the pressure-sensing bellows P0 can be completely suppressed and the amount of change ΔLa' in the displacement La' from the natural length of the pressure-sensing bellows 51' itself and the adjusting spring 41' can be made extremely large, thereby reliably eliminating the concern (hunting due to a small amount of change in the valve opening direction).

[0128] As described above, in the pressure regulating valve 100b of the second embodiment, as a hunting frequency reduction means (1), the effective pressure-receiving diameter Dx' of the pressure-sensing bellows 51' is set to be larger than the diameter Dv' of the valve port 11f' (Dx' > Dv'), thereby eliminating the conventional problem (high-frequency hunting occurring immediately after the valve is opened) and reliably maintaining high responsiveness to minute pressure changes.

[0129] Furthermore, in the pressure regulating valve 100b of the second embodiment, as a hunting frequency reduction means (2'), the internal space 51a' of the pressure-sensing bellows 51' is configured to be constantly in communication with the atmosphere via the gap Gp formed between the small diameter portion 54b' of the connecting rod 54' and the communication hole 52a' of the bellows top cover 52' ​​and the thread gap of the adjustment screw portion 42', thereby reliably eliminating the concern (hunting due to a small change in the valve opening direction).

[0130] <Other> It goes without saying that the pressure regulating valves 100a and 100b of the present embodiment can be applied to any fluid device and fluid circuit. Furthermore, the present invention is not limited to the above-described aspects, embodiments, and modified examples, and can be appropriately changed or modified within the scope of the technical concept of the present invention. [Explanation of symbols]

[0131] 100a, 100b Pressure regulating valve 1 Inflow pipe 1A primary port 1B Secondary port 2 Outflow pipe 6 Valve spring 10,10' valve body 11,11' body 11a Horizontal cave 11c central part 11d One end 11e' Valve body guide hole 11f' valve port 11g' stepped section 11h' Valve seat 11j' valve chamber 11L expanded diameter part 11n Constriction 11o rivet hole 11S Reduced diameter part 11Scm male thread engagement part 11u other end 12 Valve seat 12a Valve seat 12b Inner surface 12d Pair of rotary tool inserts 13' Connecting member 13a' opening 14' spring case 14a' Spring chamber 20,20' valve body 21,21' Valve section 22 Bowl part 22' guide section 23' Spring support 24' internal flow path 30 Slide unit 31 Cylinder parts 31a Cylinder internal space 31b Communication hole 32 Connecting member 33 Piston member 40,40' Adjustable spring unit 41, 41' Adjustment spring (biasing means) 42,42' Adjustment screw (position adjustment part) 42a, 42a' female thread 42b, 42b' male thread 43' Spring support member 50,50' Pressure-Sensing Bellows Unit 51, 51' Pressure-sensitive bellows (biasing means) 51a Interior space 52,52' Bellows top cover (slide unit) 52a boss part 52a' Communication hole 52b' Bellows top cover joint 53' Bellows bottom cover 53a' convex part 53b' Bellows bottom cover joint 54' Connecting rod (slide unit) 54a' Large diameter section 54ar' recess 54b' Small diameter section 54c' step 70 First centripetal means 71 First upper recess 72 First lower recess 73 First Ball 80 Second centripetal means 81 Second upper recess 82 Second lower recess 83 Second Ball A Containment Room B Piping block Bscf female thread engagement part Cr caulking part Dr: Ring-shaped deformation region where deformation of the pressure-sensitive bellows occurs effectively Dv,Dv' Valve port diameter Dw: Inner diameter of the bowl of the valve body Dw': Inner diameter of the contact area between the bellows lower cover and the pressure-sensing bellows, considered as one unit with the valve body Dx, Dx' Effective pressure-receiving diameter of pressure-sensing bellows Dy, Dy' Inner diameter of pressure-sensing bellows F, F', F1 to F3, F1' to F3', F3(1) to F3(3), F3'(3), F3(3-1), F3'(3-1), F3(3-2), F3'(3-2) External force acting on the valve disc in the valve opening direction Fa, Fa' (= P1 × Sv, P1 × Sv') The force acting on the valve disc due to the primary pressure Fb, Fb' (= P0 × Sw, P0 × Sw') Force acting on the valve body due to the internal pressure of the pressure-sensing bellows Fc, Fc' (= P2 × (Sv-Sw), P2 × (Sv'-Sw')) The force acting on the valve disc due to the secondary pressure Fd, Fd' (= P2 × (Sx-Sy), P2 × (Sx'-Sy')) The force acting on the effective pressure-receiving surface of the pressure-sensing bellows by the secondary pressure Fk, Fk' (= k × La, k' × La') The biasing force of the pressure-sensing bellows itself and the adjusting spring Fp1 Primary flow path Fp2 Secondary flow path G1 First Receiving Groove G2 Second Receiving Groove G3 3rd Receiving Groove G4 4th Receiving Groove Ga annular groove Gi annular seal groove Gp gap k, k': Spring constant of the composite spring (pressure-sensing bellows itself and adjusting spring) L axis La, La': Displacement of the composite spring (pressure-sensing bellows itself and adjusting spring) from its natural length Or O-ring P1 Primary pressure P2 Outlet pressure Pos Valve opening pressure setting Sv, Sv' Pressure-receiving area calculated based on the valve port diameter Sw Pressure-receiving area calculated based on the inner diameter of the bowl of the valve body Sw': Pressure-receiving area calculated based on the inner diameter of the contact area between the bellows lower cover and the pressure-sensing bellows, which are considered to be one unit with the valve disc Sx, Sx' Area calculated based on the effective pressure-receiving diameter of the pressure-sensing bellows Sy, Sy' Area calculated based on the inner diameter of the pressure-sensing bellows t0,t1,t2 time W welded section

Claims

1. a valve body having a primary side port and a secondary side port communicating with the valve port, and a valve seat surrounding the valve port; a valve body that moves in an axial direction and seats on or leaves the valve seat; a biasing means disposed along the axial direction between the other end of the valve element and the valve main body; a position adjustment unit capable of adjusting the biasing force of the biasing means; a hunting frequency reducing means for reducing the frequency of hunting of the valve body relative to the valve seat; Equipped with the biasing means comprises an adjusting spring and a pressure-sensitive bellows; In the valve closed state, A force acting on the valve body from the primary pressure and a force acting on the effective pressure-receiving surface of the pressure-sensing bellows are applied to the valve body in the valve opening direction, respectively, and a force acting on the valve body in the valve closing direction from the internal pressure of the pressure-sensing bellows, a force acting on the valve body from the secondary pressure, and a biasing force of the pressure-sensing bellows itself and an adjusting spring, 10. A pressure regulating valve according to claim 9, wherein the hunting frequency reducing means is configured to set the effective pressure receiving diameter of the pressure sensing bellows to be larger than the diameter of the valve port.

2. the valve main body includes a main body having the secondary side port, and a valve seat portion that is separate from the main body, is arranged on one end side of the main body, and has the primary side port and the valve seat, The pressure regulating valve according to claim 1 , wherein the position adjusting portion is configured to be able to adjust the relative positions of the valve seat portion and the main body in the axial direction.

3. The pressure-sensing bellows further includes a slide unit provided in the sealed space thereof, The slide unit is a cylindrical cylinder member fixed to the valve body; a piston member fixed to the main body and supported so as to be movable forward and backward relative to the cylinder member; Equipped with a cylinder internal space is defined by the cylinder member, the piston member, and the valve body; 3. The pressure regulating valve according to claim 1, wherein the hunting frequency reducing means is configured to constantly communicate the cylinder interior space with the sealed space.

4. The pressure-sensing bellows further includes a slide unit provided in the internal space thereof, The slide unit is a bellows top cover having a communication hole and fixed to the valve body; a connecting rod connected to the valve body and supported so as to be movable forward and backward relative to the bellows upper cover; Equipped with 2. The pressure regulating valve according to claim 1, wherein the hunting frequency reducing means is configured to constantly communicate the internal space of the pressure-sensing bellows with the atmosphere.

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