Regulator

Abstract: In a regulator for pressurized fluid, the opening and closing operations of a poppet valve 22 are stabilized by preventing a diaphragm 15 and the poppet valve 22 from being inclined so that the pressure adjusting accuracy of the regulator is increased. This is achieved by fitting the diaphragm 15 with a piston 18 and guiding the poppet valve 22 and the piston 18 with a sleeve 19 by slidably inserting the piston 18 into the sleeve 19.

Description: The present invention relates to a regulator for adjusting the pressure of pressurized fluid such as compressed air. Such a regulator receives pressurized fluid from an inlet port and regulates the pressure thereof to a set point at which it is discharged from an outlet port. One example thereof is disclosed in United States Patent No. 5,458,001. The regulator comprises a valve seat disposed in a fluid flow path interconnecting the inlet port and the outlet port, a diaphragm movably disposed in the outlet side of the valve seat, a poppet valve connected to the diaphragm for opening and shutting the valve seat hole from the inlet side by movement of the diaphragm, and a pressure-adjusting spring for urging the diaphragm in the direction that the poppet valve opens the valve seat. The poppet valve opens and shuts the valve seat to provide an opening corresponding to the difference between the force of the outlet side fluid pressure mutually inversely applied to the diaphragm and the pressure regulating spring force, so that the fluid pressure in the inlet side is reduced and regulated at a set point. The diaphragm is prone to move not only in the axial direction but also at an angle thereto. As a result the regulator has a disadvantage in that the poppet valve connected to the diaphragm is likely to contact and separate from the valve seat in an inclined state thereof so that the opening and shutting operation of the poppet valve is unstable, resulting in poor accuracy of pressure adjusting. A further problem is that localized wear is prone to be produced by the contact with, and separation from, the valve seat of the poppet valve which reduces the durability of the regulator. US-A-5492146 discloses a sanitary pressure regulator comprising a pressure sensing chamber, downstream of an orifice, has its upper portion defined by a diaphragm. A valve stem, mounted on the diaphragm, extends downwardly through the orifice and has a plug disposed on the upstream side of the orifice. A valve spring, is disposed in a spring housing and acts through a lower spring retainer to yieldingly resist movement of the valve plug to a position which would restrict fluid flow. The spring retainer is guided for upwards sliding movement relative to the spring housing by upper and lower lugs engaging a bore of the spring housing. The spring housing, compression spring and lower retainer form a unit which can be mounted on and detached from a passage housing. The valve stem is mounted on the diaphragm by a nut which is threaded onto a portion of the stem which projects above the diaphragm. Provision is made to lock the valve stem in an open position to facilitate the use of high pressure fluid in cleaning the regulator. In an alternate embodiment, the valve stem is axially fixed relative to the lower spring retainer and a disc engages the lower surface of the diaphragm. In another embodiment, the valve plug is yieldingly maintained in engagement with the outlet from the orifice to regulate. This embodiment also employs a compression spring and lower spring retainer mounted in a spring housing and further has means for permitting the compression spring to assume its free length so that a second spring, acting on the spring retainer, can dispose the valve stem in an open position and the regulator drained. One object of the present invention is to improve the means for stabilizing the opening and shutting operations of the poppet valve by preventing the diaphragm and the poppet valve from being inclined. Another object of the present invention is to eliminate the localised wear in the regulator so as to increase its durability. A regulator according to the present invention is defined by claim 1. When the piston is pressed by a pressure-adjusting spring of pressure-setting mechanism to move the diaphragm towards the valve seat, the poppet valve separates from the valve seat to open the valve seat hole, so that the pressurized fluid on the inlet side flows to the outlet side via the valve seat hole. The outlet side fluid pressure on the diaphragm produces an operating force in the direction opposite to that of the pressure-adjusting spring which in turn causes the poppet valve to open the valve seat an amount corresponding to the force difference therebetween. When the force of the fluid pressure on the outlet side is smaller than the spring force, the poppet valve opens to introduce the pressurized fluid from the inlet side toward the outlet side. When the force of the fluid pressure on the outlet side increases and so the difference from the spring force is reduced, the diaphragm moves away from the valve seat, so that the amount of opening of the poppet valve decreases. When the pressure difference is reduced to zero to keep the operating forces in equilibrium, the poppet valve closes to set the fluid pressure in the outlet side. Since the diaphragm is guided by the sleeve via the piston, the displacement thereof in response to the outlet side pressure is securely and reliably performed only in the axial direction without inclination from the axial line or lateral runout. Accordingly, the poppet valve connected to the diaphragm also does not incline or waggle laterally and is securely displaced only in the axial direction to open and shut the valve seat, thereby resulting in improved accuracy of pressure regulation due to the stable and precise opening and shutting operations. Furthermore, since localized wear due to deviated contact cannot be produced, the durability of the regulator is also increased. The piston and the sleeve have smaller diameter front-end portions and larger diameter rear-end portions, the piston and the sleeve being in sliding contact with each other in the front-end portions and the rear-end portions, and a step portion is formed on the inner surface of the sleeve as a stop for abuttal of the rear-end portion of the piston when the piston advances fully. Thereby, not only can inclination of the diaphragm be more securely prevented but also, when the fluid pressure of the outlet side suddenly drops or when the outlet side comes under zero pressure or vacuum, the diaphragm and the piston are prevented from crashing onto the valve seat or other members and so damage and dust production can be reliably avoided. In a preferred embodiment, the regulator may further comprise a body and a cover detachably connected to the body, wherein in the body is disposed the inlet port and the outlet port and in the cover is disposed the sleeve, the piston, the diaphragm, and the pressure-setting mechanism. Between the body and the cover, an outer peripheral portion of the diaphragm is hermetically clamped and a plate for fitting the valve seat is provided, and the valve seat is clamped between the plate and the body. When the outer peripheral portion of the diaphragm is clamped between annular clamping portions formed in the body and the cover from both sides, in order to improve hermetically, it is desirable that one of these clamping portions has a planar surface while the other is a bead. In another embodiment, the body and the cover may be connected by the clamping ring having a retaining portion attached at an exterior flange on the outer periphery of the cover and a female thread portion mated with a male thread portion on the outer periphery of the body, and sliding guide means may be interposed between the retaining portion and the flange of the cover. The pressure-setting mechanism includes a return spring for urging the piston in the direction that the poppet valve closes and the return spring may include at least one of a coil spring and a leaf spring. When the return spring is a coil spring, the coil spring is disposed within the sleeve between the inner surface of the sleeve and the outer peripheral surface of the piston. When the return spring is a leaf spring, the leaf spring is formed in an annular ring and the piston is attached to the central portion of the spring while the outer peripheral portion thereof is attached to the body or the cover. Thereby, the leaf spring is fitted in a position of the rear of the diaphragm not obstructing normal deflection of the diaphragm. It is preferable that the poppet valve have a conical sealing surface and comprise a flow-restricting portion close to the center of the conical surface which fits into the valve seat hole, the conical surface in the flow-restricting portion having a steeply inclined generating line. Thereby, when the poppet valve opens, the flow-restricting portion gradually exits the valve seat hole, which prevents the valve seat hole from being opened suddenly. When the poppet valve shuts, sudden closing of the valve seat hole is also prevented owing to gradual fitting of the flow-restricting portion into the valve seat hole, resulting in reduction of variations in pressure on the outlet side. The invention will now be further described by way of example with reference to the accompanying drawings in which: Fig. 1 is a sectional view showing a regulator according to a first embodiment of the present invention. Fig. 2 is an exploded view of a part of the regulator of Fig. 1. Fig. 3 is a sectional view showing a regulator according to a second embodiment of the present invention. Fig. 4 is a sectional view of part of a regulator according to a third embodiment of the present invention. Several preferred embodiments of a regulator according to the present invention will be described in detail below with reference to the drawings. Figs. 1 and 2 show a first embodiment. A regulator 1A according to the first embodiment comprises a short-columnar body 2, a cylindrical cover 3 connected to the top surface of the body 2, and a nut-type clamping ring 4 for detachably connecting the cover 3 to the body 2. On side surfaces of the body 2, an inlet port "P" for introducing a pressurized fluid and an outlet port "A" for discharging a pressure-regulated pressurized fluid are formed. On the top surface of the body 2 is formed a pressure chamber 7 opened to these ports "P" and "A". Within the pressure chamber 7, a valve seat 8 is attached in a position opened to the inlet port "P". The inlet port "P" communicates with the pressure chamber 7 via a valve seat hole 9 in the center of the valve seat 8. The valve seat 8 is attached via a plate 11. The plate 11 is circular-plate-shaped having a central hole 11a in the center leading to the valve seat hole 9, a circular recess portion 11b surrounding the central hole 11a, and an annular fitting portion 11c in the outer peripheral portion. The plate 11 is attached between the body 2 and the cover 3 by clamping it between a step portion 2a of the body 2 for clamping and an annular clamping portion 12a of a spacer 12 forming a part of the cover 3. Simultaneously, the valve seat 8 is attached in a clamped state between the recess portion 11b of the plate 11 and the body 2. It is desirable that an annular bead 14 be formed on the body 2 to improve hermeticity between the body 2 and the valve seat 8. In the drawings, numeral 11d indicates through-holes formed in the plate 11 for communicating the outlet side of the valve seat 8, which is the pressure chamber 7, with the outlet port "A". In the outlet side of the valve seat 8, a diaphragm 15 for defining the top surface of the pressure chamber 7 is attached so as to be movable toward and away from the valve seat 8. The diaphragm 15 is attached by hermetically clamping its peripheral portion between an annular clamping portion 2b of the outer periphery of the body 2 and the annular clamping portion 12a of the outer periphery of the spacer 12. In order to improve hermeticity during the clamping, it is desirable that any one surface of those of the clamping portions 2b and 12a respectively formed on the body 2 and the spacer 12 be planar while a bead 16 be formed on the other. In the example shown in the drawing, the bead 16 is formed on the clamping portion 2b of the body 2. In the central portion of the back of the diaphragm 15 is fitted with a piston 18 while between a step portion 3a of the cover 3 and the spacer 12 is fixed a sleeve 19. Within the sleeve 19, the piston 18 is slidably accommodated. In the piston 18 and the sleeve 19, front-end portions 18a and 19a having smaller diameters and rear-end portions 18b and 19b having a larger diameter are respectively formed. The piston 18 and the sleeve 19 are slidably made contact with each other in the two portions 18a/19a and 18b/19b, so that the piston 18 is guided to be precisely movable only in the axial direction without inclining and lateral runouts. On the inner surface of the sleeve 19 is formed a step portion 19c as a stopper for abutting the rear-end portion 18b when the piston 18 advances fully. In the central front-end portion of the piston 18, a valve stem 21 is attached so as to protrude from the front surface of the diaphragm 15. The valve stem 21 extends so as to penetrate the valve seat hole 9 of the valve seat 8 with a poppet valve 22 disposed at one end thereof. The poppet valve 22 having a conical sealing surface 22a opens and shuts the valve seat hole 9 from the inlet side with the sealing surface 22a by the displacement of the diaphragm 15. The base end portion 21a of the valve stem 21 penetrates the piston 18 to protrude to the rear. In a protruded screw portion, nuts 23 for fixing are screwed. Between the back surface of the piston 18 and a spring seat 26, which is one of members forming adjusting means 25, is disposed a pressure-adjusting spring 27 for urging the piston 18 in the opening direction of the poppet valve 22 while within the sleeve 19, between the inner peripheral surface of the sleeve 19 and the outer peripheral surface of the piston 18 is disposed a first return spring 28 for urging the piston 18 in the closing direction of the poppet valve 22. One end of the return spring 28 is retained by the smaller diameter front-end portion 19a of the sleeve 19 while the other end thereof is retained by the larger diameter rear-end portion 18b of the piston 18. Any of the pressure-adjusting spring 27 and the return spring 28 is formed of a coil spring. The adjusting means 25 comprises an adjusting screw 29 rotatably disposed in the central end portion of the cover 3, the above-mentioned spring seat 26 screwed to the adjusting screw 29 and movable by the rotation of the adjusting screw 29, and a dial 30 for rotationally operating the adjusting screw 29 from the outside of the cover 3. The adjusting means 25 establishes the outlet fluid pressure by adjusting the urging force of the pressure-adjusting spring 27 and constitutes a pressure setting mechanism along with the pressure-adjusting spring 27 and the return spring 28. The above-mentioned clamping ring 4 interconnecting the body 2 and the cover 3 comprises an annular retaining portion 4a rotatably retained at an exterior flange 32 of the cover 3 in the peripheral end portion thereof and a female thread portion 4b screwed with a male thread portion 33 of the body 2 in its outer periphery. Between the retaining portion 4a and the flange 32 of the cover 3, sliding-guiding means 34 formed of a bearing, etc., are interposed. In the regulator 1A configured as above, when the piston 8 is pushed down by the pressure-adjusting spring 27 to displace the diaphragm 15 toward the valve seat 8, the poppet valve 22 separates from the valve sheet 8 to open the valve seat hole 9, so that the pressurized fluid in the inlet side (inlet port "P") flows into the outlet side (outlet port "A") via the valve seat hole 9. The fluid pressure in the outlet side is exerted on the diaphragm 15 to produce an operating force in the direction opposite to that by the pressure-adjusting spring 27 which in turn causes the poppet valve 22 to open the valve seat 8 to an amount of corresponding opening to the acting force difference therebetween. While the fluid pressure in the outlet side is smaller than the setting-pressure, the poppet valve 22 opens to introduce the pressurized fluid from the inlet toward the outlet. When the fluid pressure in the outlet side increases to reduce the pressure difference with the setting-pressure, the diaphragm 15 moves away from the valve seat 8, so that the amount of opening of the poppet valve 22 decreases. When the pressure difference is reduced to zero to keep the operating forces in equilibrium, the poppet valve 22 closes to set the fluid pressure in the outlet side. Since the diaphragm 15 is guided by the sleeve 19 via the piston 18, the displacement thereof corresponding to the outlet side pressure is securely and steadily performed only in the axial direction without inclination of the axial line or lateral runouts. In particular, since the piston 18 and the sleeve 19 are slidably made contact with each other in plural portions such as front-end portions 18a and 19a and rear-end portions 18b and 19b, the sliding is stable and inclination of the axial line can be securely prevented. Accordingly, the poppet valve 22 connected to the diaphragm 15 does not also incline or waggle laterally and is securely displaced only in the axial direction to open and shut the valve seat 8, thereby resulting in improved accuracy in pressure regulation by the stable and precise opening and shutting operations. Furthermore, since localized wear due to deviated contact cannot be produced, the durability can be also increased. Since the full advancing position of the piston 18 is defined by the step portion 19c formed on the inner surface of the sleeve 19, even when the fluid pressure of the outlet side is suddenly dropped or when the outlet side becomes under zero pressure or vacuum, troubles in that the diaphragm 15 or the piston 18 crashes on the valve seat 8 or other members to be damaged or to produce dust can be avoided with reliability. Fig. 3 shows a second embodiment of the regulator. A point of difference of a regulator 1B according to the second embodiment from the above-mentioned regulator 1A according to the first embodiment is that a second return spring 36 formed of a leaf spring is disposed therein besides the first return spring 28 formed of a coil spring. The leaf spring is formed in an annular ring and the front-end portion of the piston 18 is fitted into and retained at the central hole 36a of the spring while the outer peripheral portion thereof is retained at the inner peripheral surface of the spacer 12. Thereby, the leaf spring is closely fitted with in a position of the rear of the diaphragm 15 not obstructing normal deflection of the diaphragm 15. The second return spring 36 also has a function that when the diaphragm 15 is strongly urged by fluid pressure, excess deflection thereof is prevented by supporting it from the rear besides the function of urging the piston 18 in the returning direction in cooperation with the first return spring 28. In addition, when such the leaf spring-type second return spring 36 is provided, the first return spring 28 formed of a coil spring may be eliminated. Since the configuration except the above point is substantially the same as that of the regulator 1A according to the first embodiment, like reference characters designate like principal portions common to those of the first and second embodiments, and description thereof is abbreviated. Fig. 4 shows an essential part of a regulator according to a third embodiment. In the regulator according to the third embodiment, a flow-restricting portion is formed in the poppet valve 22 according to above-mentioned each embodiment. That is, in a portion close to the center (inside), i.e., a portion fitting into the valve seat hole 9, on the conical sealing surface 22a of the poppet valve 22, a flow-restricting portion 22b, in which a generating line is steeply inclined, is formed. When the poppet valve 22 opens, the valve seat hole 9 is gradually opened owing to the flow-restricting portion 22b so that pressurized fluid is prevented from flowing into the pressure chamber 7 suddenly. When the poppet valve shuts, the valve seat hole 9 is also gradually closed owing to the flow-restricting portion 22b so that pressurized fluid is prevented from being suddenly intercepted. Consequently, not only sudden variations in pressure accompanied with opening and shutting of the poppet valve 22 are prevented but also enfolding dust due to sudden variations in flow, losing flow uniformity due to generation of turbulence, and so forth can be securely avoided. The flow-restricting portion described as above may also be formed in the outlet side of the valve seat 8. That is, as shown in Fig. 4, the flow-restricting portion 38 having a conical surface may be formed in a portion of the base end side of the valve stem 21 located in the pressure chamber 7, so that the opening area of the central hole 11a of the plate 11 is throttled by the flow-restricting portion 38 when the poppet valve 22 is fully opened. In this manner, by forming the flow-restricting portion 38 in the outlet side of the valve seat 8, the flow when the poppet valve 22 is fully opened is restricted so that sudden variations in pressure can be more effectively prevented. That is, when fluid pressure in the outlet side is largely reduced and thereby the poppet valve 22 is fully opened to supply the maximum flow, enfolding dust due to sudden variations in flow, losing flow uniformity due to generation of turbulence are prone to be generated. However, the pressure rises smoothly because the opening area of the central hole 11a is throttled by the flow-restricting portion 38 to restrict the flow. In addition, the flow-restricting portion 38 may be jointly formed with the flow-restricting portion 22b in the poppet valve 22 or may be formed instead of the flow-restricting portion 22b. In the regulators described above, since the piston attached to the diaphragm is guided by the sleeve, the diaphragm securely and steadily displaces only in the axial direction; the axial line cannot be inclined; and lateral runouts cannot be generated, thereby preventing the poppet valve from inclination and lateral runouts to stabilize its opening and shutting operations, resulting in not only increasing pressure-adjusting-accuracy of the regulator but also improving its durability by preventing localized wear due to the deviated contact of the poppet valve.

Claims: A regulator comprising a body (2) having an inlet port (P) for introducing pressurized fluid and an outlet port (A) for discharging pressure-regulated pressurized fluid; a cover (3) connected to the body (2); a valve seat (8) disposed in a fluid flow path interconnecting the inlet port (P) and the outlet port (A); a diaphragm (15) disposed on the outlet side of the valve seat (8) so as to be movable toward and away from the valve seat (8); a piston (18) connected to the rear of the diaphragm (15) and moving axially with the diaphragm (15); a valve stem (21) extending from an end portion of the piston (18) toward the front of the diaphragm (15) and through a hole (9) in the valve seat (8); a poppet valve (22) disposed in an end portion of the valve stem (21) for opening and shutting the valve seat hole (9) from the inlet side in response to movement of the diaphragm (15); and a pressure-setting mechanism (25,27,28) including a pressure-adjusting spring (27) for urging the piston (18) in the direction in which the poppet valve (22) opens; and adjusting means (25) for adjusting the force of the pressure-adjusting spring (27): characterised in that a return spring (28) urges the piston (18) in the direction in which the poppet valve (22) closes; a sleeve (19) slidably contains the piston (18) for guiding its axial movement, wherein the piston (18) and the sleeve (19) are disposed in the cover (3) and have front-end portions (18a,19a) of smaller diameters than respective rear-end portions (18b,19b) thereof, the piston (18) and the sleeve (19) being in sliding contact in the front-end (18a,19a) and the rear-end portions (18b,19b), and wherein a step portion (19c) is formed on the inner surface of the sleeve (19) as a stop for abutment by the rear-end portion (18b) of the piston (18) when the piston (18) advances fully. A regulator according to Claim 1, in which the cover (3) is detachably connected to the body (2) by a clamping ring (4), and an outer peripheral portion of the diaphragm (15) is hermetically clamped between the body (2) and the cover (3) and wherein a plate (11) having a central hole (11a) and a recessed portion (11b) around the central hole (11a) is provided, and wherein the valve seat (8) is clamped between the recessed portion (11b) of the plate (11) and the body (2). A regulator according to Claim 2, wherein annular clamping portions(2b,32) are formed on the body (2) and the cover (3) for clamping the outer peripheral portion of the diaphragm (15) from both sides, one of which is planar and the other of which is a bead (16). A regulator according to either Claim 2 or Claim 3, wherein the clamping ring (4) has a retaining portion rotatably held by an exterior flange (32) on the outer peripheral end portion of the cover (3) and a female thread portion (46) mated with a male thread portion (33) on the outer periphery of the body (2), wherein sliding guide means (34) are interposed between the retaining portion and the flange (32) of the cover. A regulator according to any preceding Claim, wherein the return spring (28) includes at least one of a first return spring in the form of a coil spring and second return spring in the form of a leaf spring (36). A regulator according to Claim 5, wherein the return spring includes at least the first return spring (28), the first return spring (28) being disposed within the sleeve (19) between the inner peripheral surface of the sleeve (19) and the outer peripheral surface of the piston (18), one end of the first return spring (28) being retained at the rear-end portion of the piston (18b) and the other end thereof being retained at the front-end portion (19a) of the sleeve (19). A regulator according to Claim 6, wherein the return spring includes at least the second return spring (36), wherein the second return spring is disposed close to the rear of said diaphragm (15) in a position not obstructing normal deflection of the diaphragm (15) by attaching the central portion of the second return spring (36) to the piston (18) and the outer peripheral portion to one of the body (2) and the cover (3). A regulator according to any preceding Claim, wherein the poppet valve (22) has a conical sealing surface with a flow-restricting portion (38)close to the center of the conical surface in a portion fitting into the valve seat hole (9), the flow-restricting portion (38) of the conical surface having a steeply inclined generatrix.

Inventors: KATSUTA HIROYUKI, MIYAZOE SHINJI, TAJIMA MASAMICHI, KATSUTA, HIROYUKI, MIYAZOE, SHINJI, TAJIMA, MASAMICHI, Katsuta, Hiroyuki, SMC Corp. Tsukuba Tech. Center, Miyazoe, Shinji, SMC Corp. Tsukuba Tech. Center, Tajima, Masamichi, SMC Corp. Tsukuba Tech. Center
Applicants: SMC CORP, SMC CORPORATION
Application year: 2000
Main classification: G05D16
IPC codes: G05D16, G01L7, F16K7