To provide a low-cost air-operated valve, an air-operated valve comprises a piston, a cylinder in which the piston is allowed to slide by operation air, and a valve section to be driven by sliding movement of the piston. The cylinder includes an outer member having a hollow portion and an inner member loaded in the hollow portion of the outer member to define a piston chamber in which the piston is allowed to slide.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an air-operated valve with a piston slidable in a cylinder by operation air to activate a valve section.

2. Description of Related Art

As an air-operated valve arranged to activate a valve section by sliding a piston in a cylinder by operation air, there is for example an air-operated valve1100as shown inFIG. 31.

The air-operated valve1100includes, in outer shape or appearance, an actuator section1110attached to a body1101, and further a hand-operated mechanism1120attached to the actuator section1110for forcibly actuating the actuator section1110.

The body1101is formed with a valve seat1104between a primary-side passage1102and a secondary-side passage1103. A diaphragm1105is placed with its outer edge clasped between the body1101and a holder1106while an adaptor1107is threadedly engaged in the body1101with the holder1106intervening therebetween. A stem1108is slidably mounted in the holder1106and held in contact with a back-pressure side of the diaphragm1105. The actuator section1110, which is threadedly engaged in the adaptor1107so that a center rod1118abuts on the stem1108, is coupled to the body1101.

Parts or components of the actuator section1110, except for O-rings, are made of rigid metal such as stainless steel for ensuring pressure resistance to operation air. The actuator section1110includes a hollow base1111and a cap1112which are threadably connected to each other to constitute a cylinder. Those base1111and cap1112hold a partition plate1113therebetween, thereby defining a first piston chamber1114and a second piston chamber1115partitioned by the partition plate1113. In the first and second piston chambers1114and1115, first and second pistons1116and1117are slidably mounted respectively, forming hermetically divided pressure chambers1114a,1115aand backpressure chambers1114b,1115b.

The center rod1118is disposed passing through the first piston1116, the partition plate1113, and the second piston1117and fixed to the first and second pistons1116,1117respectively. In the backpressure chamber1114bof the first piston chamber1114, a compression spring1119is set in compressed form so that its resilient (or elastic) force acts on the stem1108through the first piston1116and the center rod1118to bring the diaphragm1105into contact with the valve seat1104.

The center rod1118has a main flow passage1118abored therein extending from an upper surface to a middle point along a central axis of the center rod1118, and branch passages1118b,1118cformed extending perpendicular to the main flow passage1118a. The branch passages1118b,1118care so formed as to communicate with the pressure chambers1114a,1115arespectively. An upper end of the center rod1118is placed in an air supply and exhaust passage1112bformed in the cap1112to allow operation air to be supplied to the pressure chambers1114a,1115avia the flow passages1118a,1118b, and1118cof the center rod1118or to be discharged from the pressure chambers1114a,1115a. On the other hand, the cap1112is formed with a first breathing hole1112acommunicating with the backpressure chamber1114b. The base1111is formed with a second breathing hole1111acommunicating with the backpressure chamber1115b. Accordingly, in the actuator section1110, the center rod1118is caused to move upward and downward in the figure in accordance with balance between the resilient force of the compression spring1119and the pressure of the operation air acting on the pressure chambers1114a,1115a.

In the air-operated valve1100having the above configuration, while no operation air is supplied to the air supply and exhaust passage1112b, the resilient force of the compression spring1119acts on the diaphragm1105through the first piston1116, center rod1118, and stem1108to hold the diaphragm1105in contact with the valve seat1104. In this case, a control fluid supplied to the primary-side passage1102is blocked from flowing in the secondary-side passage1103via the valve seat1104.

When the operation air is supplied to the air supply and exhaust passage1112band the inner pressures of the pressure chambers1114a,1115aexceed the resilient force of the compression spring1119, the center rod1118is moved upward in the figure away from the stem1108. Accordingly, the diaphragm1105is not pressed toward the valve seat and thus moves away from the valve seat1104by its own reaction force. When the control fluid is then supplied to the primary-side passage1102, the control fluid is permitted to flow from the primary-side passage1102to the secondary-side passage1103via the valve seat1104.

Thereafter, when the operation air is discharged from the pressure chambers1114a,1115brespectively through the air supply and exhaust passage1112b, the inner pressures of the pressure chambers1114a,1115bis reduced below the resilient force of the compression spring1119, allowing the center rod1118to move downward. The center rod1118presses the diaphragm1105through the stem1108toward the valve seat, thus bringing the diaphragm1105into contact with the valve seat1104. This interrupts the flow passage, blocking the control fluid from flowing from the primary-side passage1102to the secondary-side passage1103via the valve seat1104.

The above conventional valve is disclosed in for example JP2005-214231A.

SUMMARY OF THE INVENTION

In the conventional air-operated valve1100, the cylinder is constituted of the base1111and the cap1112both made of rigid metal and engaged with each other. These base1111and cap1112have to be machined to form large hollow portions for the first and second piston chambers1114,1115. If the sliding surfaces along which the first and second pistons1116,1117slide are rough, the O-rings attached to the first and second pistons1116,1117may be damaged, leading to leakage of the operation air from the pressure chambers1114a,1115ainto the backpressure chambers1114b,1115b. To avoid such damages, the base1111and the cap1112have to be machined to form the respective sliding surfaces with improved surface roughness. The conventional air-operated valve1100requires many cutting works to the base1111and the cap1112made of metal ensuring pressure resistance, which would cause wasteful consumption of metal materials and high costs.

The present invention has been made to solve the above problems and has an object to provide a low-cost air-operated valve.

To achieve the above object, the present invention provides an air-operated valve comprising a piston, a cylinder in which the piston is allowed to slide by operation air, and a valve section to be driven by sliding movement of the piston, wherein the cylinder includes: an outer member having a hollow portion; and an inner member loaded in the hollow portion of the outer member, defining a piston chamber in which the piston is allowed to slide.

The air-operated valve configured as above has the function of a cylinder including the function of causing a piston to slide and the structural function of ensuring pressure resistance to operation air. Specifically, the air-operated valve comprises the inner member that serves as a member having the former function and the outer member that serves as a member having the latter function. Thus, the inner member formed with the piston chambers correspondingly has a more complicated construction than the outer member. According to the air-operated valve, therefore, the outer member and the inner member are made of different materials according to respective intended use, thereby achieving a reduction in cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A detailed description of preferred embodiments of an air-operated valve embodying the present invention will now be given referring to the accompanying drawings.

First Embodiment

A first embodiment of the air-operated valve of the present invention is first explained.FIG. 1is a sectional view of an air-operated valve1A of the first embodiment.FIG. 2is a plan view of the air-operated valve ofFIG. 1.

The air-operated valve1A of the first embodiment includes a cylinder19arranged such that an inner member20including a plurality of inner parts22A,22B,22C is loaded in an outer member21whose both open ends are closed by a base25which is an example of a “second closing plate” and a cap26A which is an example of a “first closing plate” respectively. Thus, the cylinder19has a double walled construction formed by the outer member21and the inner member20.

As shown inFIG. 1, the air-operated valve1A of the first embodiment includes a valve section2for controlling control fluid and an actuator section3A for exerting a driving force to the valve section2. In the air-operated valve1A, the actuator section3A is coupled to a body4by use of an adaptor11, providing a cylindrical outer shape.

The valve section2is built in the body4of a cylindrical shape made of a metal material having rigidity and heat resistance such as stainless steel and aluminum. In the lower surface of the body4, a primary-side port5and a secondary-side port6are provided. In the upper surface of the body4, on the other hand, a cylindrical mounting hole7is formed. An annular valve seat8is centrally placed on the bottom of the mounting hole7. The primary-side port5and the secondary-side port6are allowed to communicate with each other via the valve seat8.

In the valve section2, a diaphragm9is set in the mounting hole7of the body4and the outer edge of the diaphragm9is held down by a holder10. Specifically, the adaptor11inserted between the inner surface of the mounting hole7and the outer surface of the holder10is screwed in the body4, tightly holding the outer edge of the diaphragm9between the body4and the holder10. The diaphragm9is made of resin or metal in a thin film shape so as to be deformable. The holder10and the adaptor11are made of a metal material having heat resistance and rigidity. In the holder10, a metal stem13is fitted in contact with the diaphragm9to transmit the driving force of the actuator section3A to the diaphragm9through the stem13.

The actuator section3A has a cylindrical outer shape as shown inFIGS. 1 and 2. As shown inFIG. 1, the actuator section3A has a normally closed air cylinder construction. In the actuator section3A, the cylinder19housing pistons23,24which are examples of “first and second pistons” is constituted of a plurality of separate parts or components, namely, the outer member21, the inner parts22A,22B,22C, the base25, and the cap26A.

In the actuator section3A, the inner parts22A,22B,22C and the pistons23,24are alternately loaded as shown inFIG. 1in the pipe-shaped outer member21. The base25and the cap26A are attached to both open ends of the outer member21to hold the inner parts22A,22B,22C between the base25and the cap26A. Thus, the cylinder19has a double walled construction. The inner parts22A,22B,22C are fixed in stacked relation in the outer member21to define a first piston chamber27and a second piston chamber28. The pistons23,24are slidably loaded in the first and second piston chambers27,28respectively, thereby partitioning the first piston chamber27into a pressure chamber27aand a backpressure chamber27band the second piston chamber28into a pressure chamber28aand a backpressure chamber28b. In the backpressure chamber28bof the second piston chamber28, a compression spring29A which is an example of an “urging member” is set in compressed form to constantly urge the pistons23,24downward in the figure toward the valve seat8(in the direction of the valve seat).

The cylinder19of the actuator section3A is constructed as above of a combination of separate parts or components, i.e., the outer member21, the inner parts22A,22B,22C, the pistons23,24, the base25, and the cap26A. The actuator section3A is fixed to the body through the adaptor11. Accordingly, the pistons23,24may not be placed coaxially with the valve seat8due to variations in part size or in assembly work, but the pistons23,24will transmit the driving force to the diaphragm9through the cylindrical stem13. To be specific, even where the piston23comes into contact with a slightly off-center portion of the stem13, the driving force can be transmitted to the diaphragm9in dispersed manner through the stem13brought in surface contact with the diaphragm9. This makes it possible to hold the diaphragm9into close contact with the valve seat8by a circumferentially uniform force.

Operation air is supplied to or discharged from the aforementioned air-operated valve1A through an air supply and exhaust port85centrally formed opening on the upper surface of the cap26A. This supply and exhaust port85communicates with the pressure chambers27a,28aof the first and second piston chambers27,28through inner passages (mentioned later) formed in the pistons23,24. Further, the air-operated valve1A is formed with a plurality of conducting passages31between the inner surface of the outer member21and the outer surfaces of the inner parts22A,22B,22C for providing communication between the backpressure chambers27b,28bof the first and second piston chambers27,28and a breathing hole12formed in the adaptor11. Accordingly, in the air-operated valve1A, the pistons23,24can be moved axially in response to the balance between the resilient force (reaction force, or restoring force) of the compression spring29A and the inner pressures of the pressure chambers27a,28a, thereby transmitting the driving force to the valve section2.

FIG. 3is a longitudinal sectional view of the first and second pistons23,24ofFIG. 1.

The piston23is an integrally-molded component including a piston portion41, a piston rod42which is an example of a “first piston rod”, and a piston rod43. The piston portion41has a cylindrical shape having an outer diameter almost equal to an inner diameter of each inner part22A,22B, and22C. The piston portion41is circumferentially formed with a mounting groove44on the outer periphery for receiving a seal member33(seeFIG. 1) such as an O-ring made of an elastic material, e.g., rubber or resin. The piston rods42,43are also circumferentially formed with mounting grooves45,46on respective outer peripheries for receiving seal members32,34(seeFIG. 1) such as O-rings made of an elastic material, e.g., rubber or resin.

The piston23is provided with an inner passage formed in T-shape including a main passage47forming part of a “bypass passage” and a branch passage48which is an example of a “first branch passage”. The main passage47is formed axially extending from the center of the end face of the piston rod43to the branch passage48. The branch passage48is formed in a position of the piston rod42corresponding to the pressure chamber27aand between the mounting groove45and a proximal end of the piston rod42continuous with the piston portion41, and also the branch passage48is formed extending through the piston rod42in its diametrical direction. The branch passage48has a rectangular section larger in horizontal width than in vertical height.

On the other hand, the piston24is an integrally-molded component including a piston portion51and a piston rod52which is an example of a “second piston rod”. The piston portion51has a cylindrical shape having an outer diameter almost equal to an inner diameter of each inner part22A,22B, and22C. The piston portion51is circumferentially formed with a mounting groove53on the outer periphery for receiving a seal member35(seeFIG. 1) such as an O-ring made of an elastic material, e.g., rubber or resin. The piston rod52is substantially identical in shape to the piston rod42. The piston rod52is also circumferentially formed with a mounting groove54on the outer periphery for receiving a seal member36(seeFIG. 1) such as an O-ring made of an elastic material, e.g., rubber or resin.

As shown inFIGS. 1 and 3, the piston24is provided with an inner passage formed in T-shape including a main passage55forming part of the “bypass passage” and a branch passage56which is an example of a “second branch passage”. The main passage55is formed axially extending from the center of the end face of the piston portion51to the branch passage56. The branch passage56is formed in a position corresponding to an insertion hole81of the cap26A and closer to a distal end (an upper end) of the piston rod52than the mounting groove54. Accordingly, a distance between the branch passage56and the piston portion51of the piston24is longer than a distance between the branch passage48and the piston portion41of the piston23. The branch passage56is formed extending through the piston rod52in its diametrical direction. The branch passage56has a rectangular section larger in horizontal width than in vertical height.

The piston24is further provided with a fitting recess57around an open end of the main passage55so as to be concentric with the main passage55. Communication passages58are radially formed in the bottom wall of the fitting recess57to allow part of operation air flowing in the main passage55to flow in the fitting recess57.

The piston24further includes a guide portion59formed continuous with a proximal end of the piston rod52and larger in diameter than the piston rod52. This guide portion59is inserted in the compression spring29A to support stable expansion and contraction of the compression spring29A in an axial direction.

The above pistons23,24are coupled to each other with the piston rod43of the piston23engaging the fitting recess57of the piston24so that the end face of the piston23is held in contact with the bottom surface of the fitting recess57, providing communication between the main passage55of the piston24and the main passage47of the piston23.

The parts or components constituting the cylinder19of the air-operated valve1A are explained below.

The inner parts22A,22B,22C shown inFIG. 1are resin molded components made of heat-resistive and rigid resin by injection molding, such as PPS, PBT, POM, PA, and PVDF. The inner parts22A,22B,22C are identical in shape, and therefore only the inner part22B is described below for sake of simplicity without repeating respective explanations of the other inner parts22A,22C.

As shown inFIG. 1, the inner part22B is formed in a cup shape having a cylindrical peripheral wall with an open end and a closed end (a closed end wall). The inner part22B is designed to have the outer diameter almost equal to the inner diameter of the outer member21and the inner diameter of the peripheral wall almost equal to the outer diameter of the piston51. The peripheral wall of the inner part22B is held in contact with the inner surface of the outer member21when the inner part22B is loaded in the outer member21, and therefore the peripheral wall is formed to be thin. On the other hand, the closed end (wall) of the inner part22B serves as a partition plate that divides a hollow portion of the outer member21into the first and second piston chambers27,28when the inner part22B is loaded in the outer member21. Thus the closed end wall is formed to be thick to ensure the pressure resistance to operation air.

FIG. 4is a perspective external view of the inner part22B, which is in an upside-down orientation from that shown inFIG. 1.

The inner part22B is provided, centrally in the closed end wall, with a through hole61through which the piston rod43of the piston23(or the piston rod42or52in the case of the inner part22A or22C) is inserted. An annular groove62is formed in the outer surface of the closed end wall so as to be concentric with the through hole61. Additionally, a plurality of guide grooves63are formed extending radially outwardly between the through hole61and the annular groove62. In the peripheral wall of the inner part22B, D-cut passages64(only one of them is illustrated inFIG. 4) are formed extending in parallel with the longitudinal axis of the inner part22B so as to be continuous with the guide groove63. The inner part22B is further formed, on the open end, with a cutout65continuous with the corresponding D-cut passage64.

The base25and the cap26A are fixed to the upper and lower ends of the outer member21respectively by swaging as shown inFIG. 1, completing the outer shape of the actuator3A. The outer member21, base25, and cap26A, all of which are made of metal, surround the resin inner parts22A,22B,22C to effectively enhancing the strength of the inner parts22A,22B,22C.

FIG. 5is a sectional view of the cap26A, the base25, and the outer base21, shown inFIG. 1, in an exploded form to show a relationship therebetween.

The outer member21has a cylindrical shape having open ends. This outer member21is produced by making a thin pipe made of metal having rigidity such as stainless steel by a drawing process or an extruding process and then cutting the pipe into a part of a predetermined length. The entire length of the outer member21is determined based on how many piston chambers are to be provided by the inner parts22(22A,22B,22C) to be loaded in stacked relation. The wall thickness of the outer member21is determined in consideration of pressure resistance to operation air, which is 0.5 mm in the present embodiment.

The base25and the cap26A are attached to both ends of the outer member21while holding the inner parts22A,22B,22C in stacked relation in the outer member21against the resilient force of the compression spring29A, thus forming a space (clearance) inside the outer member21. The base25and the cap26A are made of a rigid metal material such as stainless steel and aluminum into a cylindrical shape. The base25and the cap26A are in contact with the closed ends of the inner parts22A,22C respectively to support the inner parts22A,22C.

The base25is designed to have a cylindrical shape with an outermost diameter equal to or larger than the outer diameter of the outer member21. The base25is centrally formed with a connection hole71having an internally threaded surface (a female screw) engaging an externally threaded surface (a male screw) of the adaptor11. The base25is formed, on one end face (the upper surface inFIG. 5), with a positioning recess72concentric with the connection hole71for positioning the inner part22A. A press-fit portion73having a press-fit allowance is circumferentially provided on the end face with the positioning recess72in such a manner as to be press-fitted in an open end of the outer member21. The base25is further formed with an annular groove74on the outer periphery, radially inwardly from the press-fit portion73. In this annular groove74, the end portion of the outer member21is inwardly deformed or bent to be swaged.

The cap26A is designed to have a cylindrical shape with an outermost diameter equal to or larger than the outer diameter of the outer member21. The cap26A is formed with a cylindrical insertion hole81opening on the center of one end face (the lower surface inFIG. 5) of the cap26A. The insertion hole81receives the piston rod52of the piston24in a noncontact manner. In the lower surface of the cap26A, an annular mounting groove82is circumferentially formed around the insertion hole81for receiving a seal member37(seeFIG. 1) such as an O-ring made of an elastic material such as rubber and resin. The mounting groove82is formed to face the annular groove62of the inner part22C. A press-fit portion83having a press-fit allowance is circumferentially provided on the lower surface of the cap26A in such a manner as to be press-fitted in the other open end of the outer member21. The cap26A is further formed with an annular groove84on the outer periphery, radially inwardly from the press-fit portion83. In this annular groove84, the end portion of the outer member21is inwardly deformed or bent to be swaged. Such cap26A is provided with the air supply and exhaust port85opening on the other end face (the upper surface inFIG. 5) and continuous with the insertion hole81.

A manner of assembling the air-operated valve1A having the above parts or components is explained as an example.

Firstly, the valve seat8is fixed to the mounting hole7of the body4and then the diaphragm9is set in the mounting hole7. The holder10is inserted in the mounting hole7of the body4in such a manner as to hold down the outer edge of the diaphragm9. The stem13is fitted in the holder10and then the adaptor11is threadedly engaged in the body4to be fixed therein. Thus, the valve section2is completed.

The actuator3A is assembled in the following manner. The seal members32,33,34,35,36are placed respectively in the mounting grooves45,44,46of the piston23and the mounting grooves53,54of the piston24. The press-fit portion73of the base25is press-fitted in the open end (the lower end) of the outer member21. Then, the inner part22A, piston23, inner part22B, piston24, compression spring29A, and inner part22C are loaded in order in the outer member21. At this time, the piston rod42of the piston23is inserted in the through hole61of the inner part22A to project downward from the base25. The cap26A is fitted in the open end (the upper end) of the outer member21by inserting the piston rod52protruding upward from the through hole61of the inner part22C into the insertion hole81and press-fitting the press-fit portion83into the open end of the outer member21while pressing the seal member37between the annular groove62of the inner part22C and the mounting groove82of the cap26A. At this stage, the inner parts22A,22B,22C, the pistons23,24, and the compression spring29A are temporarily held in the outer member21. Then, both ends of the outer member21are fixedly swaged on the base25and the cap26A along the respective grooves74,84.

The actuator section3A is then coupled to the valve section2. Specifically, the adaptor11threadedly fixed to the body4is threaded in the connection hole71of the base25. At this time, the piston rod42of the piston23protruding outward from the base25abuts on the stem13, transmitting the resilient force of the compression spring29A acting on the pistons23,24to the diaphragm9through the stem13to place the diaphragm9in contact with the valve seat8. Thus, the air-operated valve is completely assembled.

<Passage Configuration for Operation Air>

The passage configuration for operation air in the air-operated valve assembled as above is explained below.FIG. 6is an explanatory view showing a passage configuration for operation air in the air-operated valve1A shown inFIG. 1.

The air supply and exhaust port85communicates with the pressure chamber27aof the first piston chamber27via the insertion hole81of the cap26A, the branch passage56and main passage55of the piston24, and the main passage47and branch passage48of the piston23. Further, the air supply and exhaust port85communicates with the pressure chamber28aof the second piston chamber28via the insertion hole81of the cap26A, the branch passage56, main passage55, communication passage58, and fitting recess57of the piston24.

As above, the air-operated valve1A includes passages for supplying/discharging the operation air to/from the pressure chambers27a,28athrough the passages47,48of the piston23and the passages55,56of the piston24.

The air-operated valve1A further includes the conducting passages31as illustrated by dotted areas inFIG. 6to provide communication between the backpressure chambers27b,28bof the first and second piston chambers27,28and the single breathing hole12of the adaptor11.

The inner parts22A,22B,22C form spaces between the respective D-cut passages64formed on the outer peripheries and the outer member21. The backpressure chamber27bof the first piston chamber27is communicated with the space defined by the D-cut passage64of the inner part22A via the cutouts65of the inner part22A and the guide grooves63of the inner part22B. The backpressure chamber28bof the second piston chamber28is communicated with the space defined by the D-cut passages64of the inner parts22B,22C via the cutouts65of the inner parts22B,22C.

Between the closed end of the inner part22A and the base25, a clearance is produced by the annular groove62and the guide grooves63of the inner part22A. This clearance is communicated with the space formed between the inner parts22A,22B,22C and the outer member21and simultaneously communicated with the center hole of the adaptor11provided with the breathing hole12communicating with the center hole.

In the air-operated valve1A, as above, the space between the inner parts22A,22B,22C, the space between the inner parts22A,22B,22C and the outer member21, and the space between the inner part22A and the base25define the conducting passages31for provide communication between the backpressure chambers27b,28bof the first and second piston chambers27,28and the breathing hole12of the adaptor11.

<Explanation of Working of Air-Operated Valve>

The operation of the air-operated valve1A of the first embodiment is described below.

The air-operated valve1A is mounted on a mounting plate, a semiconductor manufacturing device, or others with bolts (not shown) inserted and tightened in mounting holes14of the body4as shown inFIG. 2. The air-operated valve1A is connected to an air supply and exhaust control device (not shown) by use of a pipe (not shown) connected with the air supply and exhaust port85for controlling supplying/discharging of the operation air with respect to the air-operated valve1A.

In the air-operated valve1A, the pistons23,24are held down by the resilient force of the compression spring29A while no operation air is supplied to the air supply and exhaust port85, placing the diaphragm9in contact with the valve seat8through the stem13. Accordingly, the control fluid supplied to the primary-side port5is blocked from flowing in the secondary-side port6via the valve seat8.

When the operation air is supplied to the air-operated valve1A through the air supply and exhaust port85, the operation air is allowed to flow in the pressure chamber27aof the first piston chamber27via the branch passage56and the main passage55of the piston24and the main passage47and the branch passage48of the piston23. The operation air is simultaneously allowed to flow in the pressure chamber28avia the branch passage56and the main passage55of the piston24, the communication passage58, and the fitting recess57. When the inner pressures of the pressure chambers27a,28aare increased to exceed the resilient force of the compression spring29A, the pistons23,24are smoothly moved upward in the figure (in an opposite direction to the valve seat8) while pressing the air out of the backpressure chambers27b,28binto the conducting passages31to be exhausted through the breathing hole12. Thus, the piston rod42is moved away from the stem13, eliminating the pressure exerted on the diaphragm9in the direction of the valve seat. Thus, the diaphragm9is allowed to move away from the valve seat8by its own reaction force. In this state, the control fluid when supplied to the primary-side port5is permitted to flow from the primary-side port5to the secondary-side port6via the valve seat8.

Then, when the operation air is exhausted from the pressure chambers27a,28athrough the air supply and exhaust port85and the inner pressures of the pressure chambers27a,28abecome lower than the resilient force of the compression spring29A, the pistons23,24are moved downward to bring the piston rod42into contact with the stem13, exerting the pressure on the diaphragm9toward the valve seat through the stem13. At this time, air taken in through the breathing hole12is supplied to the backpressure chambers27b,28bthrough the conducting passages31for assisting smooth downward movement of the pistons23,24. With the pistons23,24, the diaphragm9is held in contact with the valve seat8to interrupt the flow passage, blocking the control fluid from flowing to the secondary-side port6via the valve seat8.

In the air-operated valve1A of the first embodiment, the function of the cylinder19includes the function of causing the pistons23,24to slide and the structural function of ensuring pressure resistance to operation air or the like. Specifically, the inner parts22A,22B,22C serve as a component for carrying out the former function and the outer member21serves as a component for carrying out the latter function (seeFIG. 1). Accordingly, the inner parts22A,22B,22C tend to be more complex in configuration than the outer member21in order to constitute the first and second piston chambers27,28. According to the air-operated valve1A of the first embodiment, the outer member21and the inner member20(the inner parts22A,22B,22C) are made of different materials according to respective intended use; for example, the outer member21is made of high-priced materials while the inner member20is made of low-priced materials, which makes it possible to appropriately utilize materials and reduce costs thereof.

Further, in the air-operated valve1A of the first embodiment, the cylinder19is configured such that the base25and the cap26A are attached to close the open ends of the cylindrical outer member21in which the inner parts22A,22B,22C are loaded (seeFIG. 1). This configuration can eliminate the need for machining to form the outer member21, base25, and cap26A into cup shape. Thus, the outer member21, base25, and cap26A have no wasted portions that have to be cut away. The air-operated valve1A of the first embodiment can therefore achieve a reduction in machining cost and material cost.

In the air-operated valve1A of the first embodiment with no additional partition plate as provided in the conventional case (seeFIG. 31), the inner parts22A,22B,22C are stacked one on another so that the open end of one of the inner parts faces the open end or closed end of another inner part, thereby forming the first and second piston chambers27,28partitioned by the closed ends of the inner parts22A,22B,22C placed in stacked relation (seeFIG. 1). The pistons23,24are placed extending through the corresponding through holes61formed in the closed end walls of the inner parts22A,22B,22C so that the pistons23,24are slidable in the first and second piston chambers27,28respectively. Such combination of the plural inner parts22A,22B,22C constituting the inner member20can provide the first and second piston chambers27,28. According to the air-operated valve1A of the first embodiment, therefore, the inner parts22A,22B,22C may be common components used for forming the first and second piston chambers27,28. This makes it possible to achieve a reduction in cost.

In the air-operated valve1A of the first embodiment, the inner parts22A,22B,22C are resin molded components made by injection molding, which needs less machining time and less cutting works. Further, the surface roughness of the inner surfaces along which the pitons23,24slide can be enhanced readily without applying cutting works, with the result that the machining cost can further be reduced. On the other hand, the outer member21is a metal pipe simply formed by a drawing process or an extruding process. Thus, the inner parts22A,22B,22C and the outer member21can be manufactured at low costs. The air-operated valve1A is also arranged such that the inner parts22A,22B,22C are loaded in the outer member21for enhancing the strength of the inner parts22A,22B,22C. Thus, the inner parts22A,22B,22C may be designed to have thin peripheral walls for downsizing. According to the air-operated valve1A of the first embodiment, the outer member21and the inner parts22A,22B,22C may have thin peripheral walls, which makes it possible to downsizing of the cylinder19, saving on machining costs of the inner parts22A,22B,22C and the outer member21, leading to a reduction in total cost.

In the air-operated valve1A of the first embodiment, furthermore, the inner parts22A,22B,22C are made of resin while the outer member21supporting the inner parts22A,22B,22C, the base25, and the cap26A are made of metal having rigidity. Such configuration can achieve weight reduction as compared with the conventional air-operated valve1100(seeFIG. 31) with the cylinder entirely made of metal. To be more specific, the air-operated valve1A of the first embodiment (seeFIG. 1) can attain a 10% reduction in total weight as compared with the air-operated valve1100(seeFIG. 31) except for the hand-operated mechanism1120.

In the air-operated valve1A of the first embodiment, the inner parts22A,22B,22C are inserted in the pipe-shaped outer member21whose both ends portions are swaged on the cylindrical base25and cap26A, thereby supporting the peripheries of the inner parts22A,22B,22C. The cylinder19can thus be assembled readily. The air-operated valve1A of the first embodiment does not need for cutting works on the base25and the cap26A to provide hollow portions as in the conventional air-operated valve1100(seeFIG. 31), so that a further cost reduction can be achieved. The outer member21may be deigned to thin if only it is enough to ensure pressure resistance to the operation air. The air-operated valve1A of the first embodiment can therefore comprise the pistons23,24larger in diameter than the conventional case without changing the outer diameter of the actuator section1110of the conventional air-operated valve1100(seeFIG. 31), so that the spring load of the compression spring29A can be increased to enhance a sealing property. Consequently, this air-operated valve1A can control higher-pressure control fluid.

The air-operated valve1A of the first embodiment comprises the conducting passages31between the inner parts22A,22B,22C and the outer member21(seeFIG. 6) to provide communication between the backpressure chambers27b,28bof the first and second piston chambers27,28and the single breathing hole12. It is therefore possible to minimize the number of machining works to form the breathing hole12.

In the air-operated valve1A of the first embodiment, further, the pistons23,24are resin molded components made of resin by injection molding. This makes it possible to reduce the number of cutting works for producing the pistons for a reduction in cost, and reduce the total weight of the air-operated valve1A.

In the air-operated valve1A of the first embodiment, the branch passage48for supplying the operation air from the main passage47to the pressure chamber27aof the first piston chamber27is rectangular in section (seeFIG. 3). In a downsized valve, the pressure chamber27ahas to be small in dimension (height) in the axial direction. If the branch passage48was circular in section; the diameter of the passage section is restricted by the height of the pressure chamber27aand thus the passage could not have a large sectional area. In the air-operated valve1A of the first embodiment, however, the branch passage48can be designed to have a section wider in horizontal width to provide a large sectional area without restriction by the height of the pressure chamber27a. In the case where the vertical height of the branch passage48in the axial direction must be 1 mm, the branch passage48is preferably designed to have a rectangular section, 1 mm in vertical height and 2.5 mm in horizontal width, which can provide a sectional area about three times larger than the circular sectional area with a diameter of 1 mm. According to the air-operated valve1A of the first embodiment, it is possible to efficiently supply and exhaust the operation air with respect to the pressure chamber27athrough the branch passage48to maintain good responsibility. In the air-operated valve1A of the first embodiment, there is no need to a totally longer piston23and a pressure chamber27aenlarged in volume.

Second Embodiment

A second embodiment of an air-operated valve according to the present invention will be described below.FIG. 7is a sectional view of an air-operated valve1B of the second embodiment.

The air-operated valve1B of the second embodiment is different in some parts or components from those of the air-operated valve1A of the first embodiment. Specifically, the outer member21and the inner parts22A,22B,22C of the actuator3A of a normally closed type are placed in an upside-down orientation together with the pistons23,24to constitute an actuator section3B of a normally open type. The air-operated valve1B of the second embodiment therefore includes many identical parts or components to the air-operated valve1A of the first embodiment. The following description is therefore focused on the differences from the first embodiment without repeating the same explanation. The identical parts and components are given the same reference codes in the figures.

The air-operated valve1B includes an actuator section3B in which the inner part22C, the piston24, the inner part22B, the piston23, and the inner part22A are stacked in this order from below in the outer member21, and upper and lower end of the outer member21are swaged on the cap26A and the base25respectively. In the air-operated valve1B, a compression spring29B which is an example of an “urging member” is set in compressed form in the backpressure chamber28bof the second piston chamber28. This compression spring29B has only to have the force for separating the piston24from the stem13and thus may be selected to have a resilient force smaller than that of the compression spring29A of the first embodiment. In the above air-operated valve1B, the pistons23,24are urged upward by the resilient force of the compression spring29B to hold the piston rod52apart from the stem13. Thus, the diaphragm9is not pressed toward the valve seat.

The piston23is loaded in the cylinder19with the piston rod52having the mounting groove54attached with the seal member36and the piston rod42having the mounting groove45unattached with the seal member32. When the piston rod42without the seal member32is inserted in the insertion hole81of the cap26A, the piston23provides a clearance between the outer surface of the piston rod42and the inner surface of the insertion hole81, whereby providing communication between the air supply and exhaust port85and the pressure chamber27aof the first piston chamber27.

On the other hand, the piston24is placed with the piston rod52inserted through the connection hole71of the base25so that the piston24is movable toward and away from the valve section2. The piston24is arranged such that a stopper90which is an example of a “blocking member” such as a steel ball and a spherical elastic member is press-fitted in the main passage55to hermetically block the main passage55. Accordingly, the air supply and exhaust port85of the cap26A is therefore allowed to communicate with the pressure chamber28aof the second piston chamber28via the insertion hole81, the branch passage48and the main passage47of the piston23, the communication passage58of the piston24, and the fitting recess57.

In the air-operated valve1B, similarly, a plurality of conducting passages31are formed between the inner parts22A,22B,22C and the outer member21by the D-cut passages64formed on the peripheries of the inner parts22A,22B,22C to provide communication between the backpressure chambers27b,28bof the first and second piston chambers27,28and the breathing hole12.

<Explanation of Working of Air-Operated Valve>

The above air-operated valve1B is arranged such that while no operation air is supplied to the air supply and exhaust port85, the piston24and the piston23are urged upward by the resilient force of the compression spring29B. Thus, the diaphragm9is not pressed toward the valve seat and therefore is placed apart from the valve seat8by its own reaction force. In this state, when a control fluid is supplied to the primary-side port5, the control fluid is permitted to flow from the primary-side port5to the secondary-side port6via the valve seat8.

When the operation air is supplied to the air supply and exhaust port85, on the other hand, the operation air is allowed to flow in the pressure chamber27aof the first piston27through the insertion hole81and simultaneously into the pressure chamber28aof the second piston28through the insertion hole81, the branch passage48and main passage47of the piston23and the communication passage58and fitting recess57of the piston24, thereby pressurizing the pressure chambers27a,28a. When the inner pressures of the pressure chambers27a,28aexceed the resilient force of the compression spring29B, the pistons23,24are moved downward while causing the air to be exhausted from the backpressure chambers28b,27bthrough the breathing hole12via the conducting passages31. Then, the piston rod52of the piston24abuts on the stem13to exert pressure on the diaphragm9toward the valve seat8. When the pistons23,24holds the diaphragm9in contact with the valve seat8, the control fluid is blocked from flowing from the primary-side port5to the secondary-side port6via the valve set8.

When the operation air is exhausted from the pressure chambers27a,28athrough the air supply and exhaust port85and the inner pressures of the pressure chambers27a,28aare reduced below the resilient force of the compression spring29B, the pistons23,24are moved upward away from the stem13. At this time, the air is supplied to the backpressure chambers27b,28bthrough the breathing hole12via the conducting passages31for assisting smooth upward movement of the pistons23,24. The diaphragm9, which does not become pressed toward the valve seat, moves away from the valve seat by its own reaction force. This permits the control fluid supplied to the primary-side port5to flow to the secondary-side port6via the valve seat8.

According to the air-operated valve1B of the second embodiment, the inner parts22A,22B,22C are loaded in the hollow portion of the outer member21to form the first and second piston chambers27,28, thereby constituting the cylinder19in a double walled construction (seeFIG. 7). This makes it possible to achieve a reduction in cost as in the case of the air-operated valve1A of the first embodiment.

The air-operated valve1B of the second embodiment adapted to exert a driving force to the valve section2by moving the pistons23,24in the cylinder19by the operation air. The valve1B is constructed in a normally closed configuration by changing the orientations of the parts and components from those in the valve1A of the first embodiment in the normally open valve. Specifically, when the inner member20(the inner parts22A,22B,22C) and the pistons23,24are to be loaded in the hollow portion of the outer member21so that the piston rods4252protrude in opposite directions to each other with respect to the piston portions41,51, they are inserted in an axially reversed direction from that in the first embodiment for the normally open valve.

In other words, the pistons23,24are arranged between the inner parts22A,22B,22C and housed in the cylinder19in order to exert the driving force to the valve section2via the piston rod42in the air-operated valve1A in the normally closed configuration as shown inFIG. 1and to exert the driving force to the valve section2via the piston rod52in the air-operated valve1B in the normally open configuration as shown inFIG. 7. The air-operated valve1B uses the pistons23,24and the inner member20(the inner parts22A,22B,22C) common to the air-operated valve1A. This makes it possible to easily change the configuration of the valve between the normally closed type (1A) and the normally open type (1B). Accordingly, there is no need to stock any special base, cap, piston for the normally open type such as the conventional air-operated valve1100(seeFIG. 31) or those for the normally closed type. According to the air-operated valve1B of the second embodiment, consequently, valve components such as the pistons23,24can be used in common between the normally open configuration and the normally closed configuration, achieving a reduction in cost.

Further, in the air-operated valve1B of the second embodiment, the compression spring29B for the normally open configuration is used in place of the compression spring29A for the normally closed configuration (seeFIGS. 1 and 7), both being different in resilient property. Accordingly, the normally open configuration and the normally closed configuration can have almost equivalent valve-closing force so that a uniform load acts on the valve section2in either case.

In the air-operated valve1B of the second embodiment, the piston23is formed with the axially extending main passage47and the branch passage48extending perpendicular to the main passage47, and the piston24is formed with the axially extending main passage55and the branch passage56extending perpendicular to the main passage55in which the stopper90is fitted to block the flow to the branch passage56. The air-operated valve1B of the normally open type can thus include the different flow passage for supplying the operation air to the pressure chambers27a,28afrom that in the air-operated valve1A of the normally closed type (seeFIGS. 1 and 7). According to the air-operated valve1B of the second embodiment mentioned as above, the internal passage configuration can be changed by simply using the stopper90in the pistons23,24placed in the reversed orientation from that in the air-operated valve1A. Thus, the pistons23,24may be common parts to reduce a machining cost and a maintenance cost for reduction in total costs of the air-operated valves while enabling supply of the operation air to the pressure chambers27a,28ain both the normally closed configuration and the normally open configuration.

In the air-operated valve1B of the second embodiment of the normally open type, the seal member36is attached to only the piston rod52and the seal member32is unattached to the piston rod42as shown inFIG. 7, different from the air-operated valve1A of the normally closed type in which the seal members32,36are attached to the piston rods42,52respectively as shown inFIG. 1. By simply attaching or detaching the seal member32with respect to the piston rod42, the same pistons23,24can be used in both the normally closed configuration and the normally open configuration by reversing their orientations. Consequently, the costs for machining and maintaining the pistons23,24can be reduced.

Third Embodiment

A third embodiment of an air-operated valve according to the present invention will be described below referring to the drawings.FIG. 8is a sectional view of an air-operated valve1C of the third embodiment, including a cap26B provided with a valve opening/closing detection sensor91.FIG. 9is a plan view of the air-operated valve1C ofFIG. 8.

The air-operated valve1C of the third embodiment is different from the air-operated valve1A of the first embodiment in that pistons23,24are fixedly provided with metal parts105,106which are an example of an “wear-resistive part” and that caps26B,26C are selectively used for changing or adding functions. The following description is therefore focused on the differences from the first embodiment without repeating the same explanation. The identical parts and components are given the same reference codes in the figures.

As shown inFIG. 8, the air-operated valve1C has an outer shape that the valve section2is coupled to the actuator section3. Upper and lower open ends of the outer member21housing the inner parts22A,22B,22C, the pistons23,24, and the compression spring29A are swaged on the base25and the cap26B.

The cap26B is equal in outer diameter to the cap26A. The upper open end of the outer member21is rotatably swaged on the cap26B. The end face (the lower surface inFIG. 8) of the cap26B is formed with a cylindrical recess101around an open end of an insertion hole81. An air supply and exhaust port85is formed to open on the other end face (the upper surface inFIG. 8) of the cap26B and be deviated radially outward from the insertion hole81. The air supply and exhaust port85communicates with the cylindrical recess101through a bypass passage102. Further, a connection hole103which is an example of a “mounting portion” is formed opening on the upper surface of the cap26B and partly overlapping the insertion hole81in misaligned relation to each other. The connection hole103is formed with internal threads (a female screw) in which the valve opening/closing detection sensor91is threadedly engaged. This sensor91is screwed and fixed in the connection hole103with a sensor portion protruding in the insertion hole81.

In the air-operated valve1C, the piston rod42of the piston23and the piston rod52of the piston24are fixedly attached, at respective distal ends, with metal parts105and106. These metal parts105,106are made of magnetized metal having high rigidity and strength, such as stainless steel and brass. The metal parts105,106are fixed to the resin piston rods42,52by an appropriate technique such as press-fitting, insert molding, bonding, and welding.

The air-operated valve1C is mounted on a mounting plate, a semiconductor manufacturing device, or others with bolts (not shown) inserted in mounting holes14. An air supply and exhaust pipe is connected from above to the air supply and exhaust port85of the air-operated valve1C. If the air supply and exhaust port85is misaligned with the air supply and exhaust pipe, a connecting work may take much time. However, the cap26B of the air-operated valve1C is rotatably swaged on the outer member21. Even if the air supply and exhaust port85is misaligned with the air supply and exhaust pipe, accordingly, the cap26B is required only to be turned after the air-operated valve1C is mounted on the mounting plate or the like, thereby adjusting the position of the air supply and exhaust port85. The air-operated valve1C is connected to an external control device not shown through an upwardly extending wire of the valve opening/closing detection sensor91.

<Explanation of Working of Air-Operated Valve>

The air-operated valve1C is arranged such that while no operation air is supplied to the air supply and exhaust port85, the pistons23,24are urged downward by the resilient force of the compression spring29A. Thus, the diaphragm9is pressed down in contact with the valve seat8through the stem13.

After that, the operation air is supplied to the air supply and exhaust port85, the operation air is allowed to flow in the pressure chamber27avia the bypass passage102, the cylindrical recess101, the branch passage56and the main passage55of the piston24, the main passage47and the branch passage48of the piston23and also flow in the pressure chamber28avia the main passage55, the communication passage58, and the fitting recess57of the piston24. When the inner pressures of the pressure chambers27a,28aexceed the resilient force of the compression spring29A, the pistons23,24are moved upward, eliminating the pressure exerted on the diaphragm9through the stem13in the direction of the valve seat, so that the diaphragm9moves away from the valve seat8by its own reaction force. In this state, the control fluid when supplied to the primary-side port5is allowed to flow from the primary-side port5to the secondary-side port6via the valve seat8.

Then, when the operation air is exhausted from the pressure chambers27a,28athrough the air supply and exhaust port85, the pistons23,24are moved downward by the resilient force of the compression spring29A to bring the piston rod42into contact with the stem13, exerting the pressure on the diaphragm9toward the valve seat8through the stem13. By this force, the diaphragm9is pressed on the valve seat8, thus blocking the flow of the control fluid supplied to the primary-side port5from flowing in the secondary-side port6via the valve seat8.

In the air-operated valve1C that is operated to open and close as above, the open/closed state is detected by the valve opening/closing detection sensor91. Specifically, when the pistons23,24are moved upward to place the air-operated valve1C in the open state, the metal part106of the piston rod52of the piston24comes close to the valve opening/closing detection sensor91. When sensing the metal part106, the sensor91determines that the air-operated valve1C in the open state and sends a detection signal representing the valve open state to the external control device not shown. When the pistons23,24are moved downward to place the air-operated valve1C in the closed state, on the other hand, the metal part106moves away from the valve opening/closing detection sensor91. When the sensor91does not detect the metal part106, the sensor91determines that the air-operated valve1C is in the closed state and accordingly sends a detection signal representing the valve closed state to the external control device not shown.

The valve opening/closing detection sensor91is detachably attached to the connection hole103of the cap26B. Accordingly, replacement of devices to be attached to the connection hole103can easily change the function to be provided in the air-operated valve1C.

FIG. 10is a sectional view of the air-operated valve1C ofFIG. 8, including the cap26B attached with a stroke adjusting knob92.FIG. 11is a plan view of the air-operated valve1C ofFIG. 10.

The air-operated valve1C shown inFIGS. 10 and 11is arranged such that the stroke adjusting knob92which is an example of a “valve opening adjustment mechanism” is threadedly engaged in the connection hole103of the cap26B. By adjusting the rotation amount (angle) of the stroke adjusting knob92, the position (distance) of the lower end portion of the knob92protruding into the insertion hole81is adjusted. In the air-operated valve1C, the pistons23,24are movable until the piston rod52comes into contact with the stroke adjusting knob92, thereby controlling the amount (stroke) of the diaphragm9when moves away from the valve seat8. At this time, the distal end of the piston rod52abuts on the stroke adjusting knob92. However, such abutment against the knob92is unlikely to cause wear or deformation of the piston rod52because of the metal part106attached to its distal end. It should be noted that a scale may be provided around the stroke adjusting knob92of the cap26B as shown inFIG. 11, which makes it possible to facilitate the control of flow rate.

FIG. 12is a sectional view of the air-operated valve1C ofFIG. 8in the valve closed state, including the cap26B attached with an opening/closing indicator.FIG. 13is a view showing the valve open state of the air-operated valve ofFIG. 12.

In the air-operated valve1C shown inFIGS. 12 and 13, the opening/closing indicator93is treadedly engaged in the connection hole103of the cap26B. The indicator93includes a rod94movable to protrude outside (upward), which is urged toward the piston rod52of the piston24, or the metal part106, by a coil spring95. According to this air-operated valve1C, upward movement of the pistons23,24causes the rod94to protrude upward from the indicator93against the resilient force of the coil spring95as shown inFIG. 13. Downward movement of the pistons23,24allows the rod94to move downward by the resilient force of the coil spring95as shown inFIG. 12. This protruding amount (length) of the rod94from the indicator93makes it possible for a user to recognize the valve open or closed state. In this case, the piston rod52is unlikely to be abraded by the rod94owing to the metal part106attached to the piston rod52.

FIG. 14is a sectional view of the air-operated valve1C ofFIG. 9, including another cap26C attached with an instant joint96, instead of the cap26B.

In the air-operated valve1C inFIG. 14, the outer member21is swaged on the cap26C attached with the instant joint96. The cap26C is formed with an air supply and exhaust port85in a position deviated radially outward from the insertion hole81to receive the instant joint96. The air supply and exhaust port85communicates with the cylindrical recess101through the bypass passage102. This air-operated valve1C enables one-touch connection of an air supply and exhaust pipe to the instant joint96for facilitating piping.

In the air-operated valve1C of the third embodiment, as above, the metal part105is attached to the distal end of the piston rod42of the piston23(seeFIG. 8), thereby increasing wear resistance and strength of the piston rod42. This can prevent degradation of the piston23even where the piston rod42abuts on the stem13to transmit the driving force to the diaphragm9. In the air-operated valve1C, the piston rod42is not abraded or damaged, so that the stroke of the pistons23,24for operating the valve section2is unlikely to vary, thus providing a stable flow rate property.

According to the air-operated valve1C of the third embodiment, the outer member21is swaged on the base25and the cap26B or26C so that the base25and the cap26B or26C are rotatable. Therefore, any rotating mechanism does not need to be added to the base25and the cap26B,26C. This contributes to a reduction in total height of the air-operated valve1C. Further, the outer member21does not need to be subjected to a cutting work to form screws. This contributes to a reduction in cost.

In the air-operated valve1C of the third embodiment, the cap26B or26C attached with one of various fluid control parts such as the valve opening/closing detection sensor91, the stroke adjusting knob92, and the opening/closing indicator93, has an outer shape identical to that of the cap26A of the first embodiment including only the air supply and exhaust port85(seeFIGS. 1,8,10,12to14). Accordingly, simple replacement of the caps26A,26B,26C to be attached to the outer member21makes it possible to arbitrarily configure the air-operated valve with an intended function such as the valve opening/closing detection function and the indicator function. The air-operated valve1C of the third embodiment, consequently, can use common parts and components except for the caps26B and26C to the air-operated valve1A and selectively have an appropriate function at low costs.

Comparing with the conventional air-operated valve1100(seeFIG. 31), the above effects are very remarkable. To be specific, when the conventional air-operated valve1100(seeFIG. 31) is to provide the valve opening/closing detection function, the cap1112itself had to be replaced with another cap having a valve opening/closing detection sensor. This cap must have a hollow portion for the piston chamber1114, which is costly to machine and incurs wasteful materials. The air-operated valve1C of the third embodiment, on the other hand, each cap26B,26C has a simple cylindrical shape formed with the air supply and exhaust port85and the connection hole103. This configuration needs less cutting works, thus reducing wasteful consumption of materials in the cutting works (seeFIGS. 8,10,12to14). Accordingly, the air-operated valve1C of the third embodiment can use the outer member21, the inner member20, and others common to the air-operated valves1A and therefore can change the functions by only replacement of the cap26A by the cap26B or26C that can be produced at low cost. According to the air-operated valve1C of the third embodiment, therefore, parts needed for function changes can be produced at lower cost than in the conventional air-operated valve1100(seeFIG. 31). It should be noted that each cap,26B,26C of the third embodiment are smaller than the conventional cap1112(seeFIG. 31) and can be stocked in any places.

In the air-operated valve1C of the third embodiment, the connection hole103of the cap26B can threadedly accommodates any one of the valve opening/closing detection sensor91, the stroke adjusting knob92, and the opening/closing indicator93(seeFIGS. 8,10,12). This makes it possible for a user to selectively attach/detach the valve opening/closing detection sensor91, the stroke adjusting knob92, and the opening/closing indicator93to change the function as needed.

In the air-operated valve1C of the third embodiment, each cap26B,26C is provided with the air supply and exhaust port85to which the air supply and exhaust pipe is connected from above (seeFIGS. 8,10,12to14). There is no need to take account of the interference of the air supply and exhaust pipe with peripheral parts. Thus, the freedom in design for installation of the air-operated valve1C can be increased. The air-operated valve1C needs no joint pipe on the periphery, saving an installation space of the air-operated valve1C, so that a plurality of the air-operated valves1C can be placed in closely-spaced relation.

Fourth Embodiment

A fourth embodiment of an air-operated valve according to the present invention will be described below referring to the drawings.FIG. 15is a sectional view of an air-operated valve1D of the fourth embodiment, showing a cap26D formed with an air supply and exhaust port85alone.FIG. 16is a plan view of the air-operated valve1D ofFIG. 15.

The air-operated valve1D of the fourth embodiment is different from the air-operated valve1C of the third embodiment in that the cap26D is constituted of two separate parts. Accordingly, the following description will be focused on the differences from the third embodiment without repeating the same explanation. The identical parts and components to those in the third embodiment are given the same reference codes in the figures.

As shown inFIG. 15, the air-operated valve1D include the cap26D constituted of a fixed plate111which is an example of a “first plate” and an optional plate112A which is an example of a “second plate”, both plates111and112A being fixed to each other with two bolts113,113inserted from above as shown inFIG. 16.

The fixed plate111is formed with a cylindrical insertion hole81provided with a cylindrical recess101around an open end thereof. The fixed plate111is further formed with a bypass passage102extending through the fixed plate111so as to be continuous with the cylindrical recess101. An annular mounting groove82for receiving the seal member37is formed in the end surface (the lower end surface) of the fixed plate111in such a manner as to surround the insertion hole81, the cylindrical recess101, and the bypass passage102. The fixed plate111is also provided with a first connection hole115which partly overlaps the insertion hole81in misaligned relation to each other. The insertion hole81is formed, on its inner surface, with an annular mounting groove114for receiving a seal member38, thereby providing a hermetically closed space between the piston rod52of the piston24and the inner surface of the insertion hole81. The fixed plate111is also provided with a press-fit portion83and a swaging groove84.

On the other hand, the optional plate112A is provided with the air supply and exhaust port85in alignment with the bypass passage102of the fixed plate111. The optional plate112A is formed with a mounting groove117for receiving a seal member39around an open end of the air supply and exhaust port85.

In the above air-operated valve1D, the outer member21is swaged on the fixed plate111. The optional plate112A is fixed to the fixed plate111with the bolts113,113, covering the first connection hole115. Accordingly, the cap26D including the optional plate112A as shown inFIG. 15has only the function of supplying and exhausting operation air through the air supply and exhaust port85.

In the air-operated valve1D of the fourth embodiment, the optional plate112A is detachably fixed to the fixed plate with the bolts113,113. This configuration makes it possible to change the functions by replacing the optional plate112A by another optional plate112B or112C.

FIG. 17is a sectional view of the air-operated valve1D ofFIG. 15including the optional plate112B provided with the valve opening/closing detection sensor91instead of the optional plate112A.FIG. 18is a plan view of the air-operated valve1D ofFIG. 17.

As shown inFIGS. 17 and 18, the air-operated valve1D is arranged such that the optional plate112B is fixed to the fixed plate111with the bolts113,113. The optional plate112B includes the air supply and exhaust port85at an off-center position to be aligned with the bypass passage102of the fixed plate111. The optional plate112B is further formed with a second connection hole116at an off-center position to be aligned with the first connection hole115. The second connection hole116has an internally threaded surface (a female screw) in which the valve opening/closing detection sensor91is treadedly engageable. The thus constructed air-operated valve1D can provide the valve opening/closing detection function in such a simple way that the bolts113,113are demounted and the optional plate112A is replaced by the optional plate112B.

FIG. 19is a sectional view of the air-operated valve1D ofFIG. 17in which the stroke adjusting knob is attached.FIG. 20is a sectional view of the air-operated valve1D ofFIG. 17in which the opening/closing indicator93is attached.

In the air-operated valve1D ofFIG. 17, the valve opening/closing detection sensor91is detachably engaged in the second connection hole116. When the stroke adjusting knob92is threadedly engaged in the second connection hole116as shown inFIG. 19, instead of the sensor91, therefore, the air-operated valve1D can provide the stroke adjusting mechanism. When the opening/closing indicator93is threadedly engaged in the second connection hole116as shown inFIG. 20, the air-operated valve1D can provide the indicator function that allows a user to visually recognize the valve open/closed state from outside.

FIG. 21is a sectional view of the air-operated valve ofFIG. 15, including the cap26D having an optional plate112C attached with the instant joint96, instead of the optional plate112A.

The optional plate112C is provided with an air supply and exhaust port85formed shorter in depth than in the optional plate112A, forming a shoulder on which the instant joint96abuts to be set in the port85. The air-operated valve1D ofFIG. 21including the optional plate112C enables one-touch connection of an air supply and exhaust pipe to the air supply and exhaust port85.

In the air-operated valve1D of the fourth embodiment in which the pistons are caused to slide in the cylinder19by use of the operation air to exert the driving force on the valve section2, the cap26D closing the upper end of the cylinder19is constituted of separate parts (the fixed plate111and the optional plate112A,112B, or112C) which are detachably connected to each other with the bolts113,113(seeFIGS. 15,17,19to21). In the optional plate112A,112B, or112C which is one of the separate parts, an intended fluid control member such as the instant joint96, the valve opening/closing detection sensor91, the stroke adjusting knob92, and the opening/closing indicator93is attached (seeFIGS. 15,17,19to21). Accordingly to the air-operated valve1D of the fourth embodiment, consequently, the optional plates112A,112B,112C can be replaced with one another while the fixed plate111remain fixed to the outer member21to add or change the function. In the air-operated valve1D of the fourth embodiment, furthermore, the fixed plate111can also be used in common, achieving a further reduction in cost.

In the air-operated valve1C of the aforementioned third embodiment, particularly, the cap26C attached with the instant joint96(seeFIG. 21) and the cap26B attached with the valve opening/closing detection sensor91or others (seeFIGS. 17,19,20) could not be replaced with each other after assembly of the air-operated valve1D in a place for practical use. By simple replacement of the optional plates112B,112C, the air-operated valve1D of the fourth embodiment can be easily configured as one of the configuration using the instant joint96and the configuration using the valve opening/closing detection sensor91or the like even in a place for practical use.

Furthermore, in the air-operated valve1D, the optional plate112B is used to selectively connect the valve opening/closing detection sensor91, the stroke adjusting knob92, or the opening/closing indicator93to the second connection hole116(seeFIGS. 17,19,20). The valve opening/closing detection sensor91, the stroke adjusting knob92, or the opening/closing indicator93is required to be replaced with a desired one to change the function. Thus, the optional plate112B no longer needs to be replaced with another.

In the air-operated valve1D of the fourth embodiment, the bolts113,113are tightened from above to fix the optional plate112A,112B, or112C to the fixed plate111(seeFIG. 16,18). This makes it easy to facilitate the replacing works for the optional plates112A,112B,112C even where the air-operated valve1D is incorporated in a manufacturing line.

It should be noted that the present invention is not limited to the above embodiments and may be embodied in other specific forms without departing from the essential characteristics thereof.

(1) For instance, the above embodiments are described about the two-tiered air-operated valve1A. As an alternative, the present invention may be configured as a three-tiered air-operated valve1E shown inFIG. 22, in which four inner parts22A,22B,22C,22D identical in shape are stacked and fixed in the outer member21, forming three piston chambers27,28,121. In this case, a protruding piston122is interposed between the pistons23and24. This piston122is internally formed with a main passage123, a fitting recess124around an open end of the main passage123, and a communication passage125in an inner circumferential surface of the fitting recess124. This configuration allows communication between a pressure chamber121aof the piston chamber121and the air supply and exhaust port85. It should be noted that the number of pistons122interposed between the pistons23and24may be changed to configure a four-tiered or more multiple-tiered air-operated valve.

As another alternative, the present invention may be configured a single-tiered air-operated valve1F as shown inFIG. 23, in which two inner parts22B,22C identical in shape are stacked and fixed in the outer member21, forming a single piston chamber28. In this case, two branch passages128,129are formed in a piston126to communicate with each other through a main passage127. This configuration allows communication between the air supply and exhaust port85and a pressure chamber28aof the piston chamber28through the branch passage128, the main passage127, and the branch passage129.

As shown in the aforementioned air-operated valves1E,1F, a single- or multiple-tiered air-operated valve can be provided as intended by simply changing the number of common inner parts22A,22B . . . . The common parts also can be used, achieving a reduction in cost.

As another alternative, the present invention may be configured as an air-operated valve1G shown inFIG. 24, in which the compression spring29B is used in place of the compression spring29A shown inFIG. 23, the seal member32is removed, the stopper90is fitted in the main passage127of the piston126, and the inner parts22B,22C are loaded in the outer member21so that the inner parts22B,22C are arranged in an axially reversed orientation from inFIG. 23as well as the piston126. In this way, the normally closed valve can be transformed to the normally open valve. Also in this example, the parts except for the compression springs29A,29B, and the seal member32may be used in common in both valve configurations be transformed from the normally closed valve to the normally open valve and vice versa, achieving a reduction in cost.

The air-operated valve1E shown inFIG. 22may also transformed from the normally closed valve to the normally open valve by removing the seal member32, replacing the compression spring29A with the compression spring29B, and fitting the stopper90in the main passage55of the piston24and loading the pistons23,24,122together with the inner parts22A,22B,22C,22D in integrally reversed orientation into the outer member21.

(2) In the above embodiments, each inner part22A,22B,22C is formed with the D-cut passages64on the outer periphery to form the conducting passages31between each inner part22A,22B,22C and the outer member21. As an alternative to the D-cut passages64, a plurality of conducting grooves131having a rectangular section may be formed on the outer periphery of each inner part22A,22B,22C as shown inFIG. 25. In this case, the conducting passages31are defined between the conducting grooves131of each inner part22A,2B,22C and the inner surface of the outer member21. As an alternative, instead of the D-cut passages64on the outer periphery of each inner part22A,22B,22C, a conducting groove132may be formed in the inner surface of the outer member21as shown inFIG. 26to form the conducting passages31between each inner part22A,22B . . . and the outer member21.

The conducting grooves132can be formed at the same time of a drawing or extruding process for the outer member21. The machining of the conducting grooves132is therefore inexpensive. Further, another alternative is to form the conducting grooves131in each inner part22A,22B,22C and also form the conducting grooves132in the outer member21.

(3) In the above embodiment, for example, both ends of the outer member21are press-fitted and swaged on the base25and the cap26A respectively.

As an alternative to such configuration, an air-operated valve1H shown inFIG. 27may be adopted in which both ends of the outer member21are press-fitted and then welded on the base25and the cap26A respectively as illustrated as portions P inFIG. 27. In this configuration, the base25and the cap26A can be tightly fixed to the outer member21, reliably preventing fluid leakage.

As another alternative, an air-operated valve1I shown inFIG. 28may be adopted in which the base25and the cap26E are not provided with the swaging grooves74and84, both ends of the outer member21are merely press-fitted or bonded on the base25and the cap26E or the press-fitted portions are bonded with adhesive or the like to fix the outer member21to the base25and the cap26E. This configuration can eliminate a machining work needed to form the swaging grooves74,84.

As another alternative, an air-operated valve1J shown inFIG. 29may be adopted in which a base135and a cap136are formed with externally threaded surfaces (male screws) respectively, while both open ends of an outer member137are formed with an internally threaded surface (a female screw) as shown in portions P2inFIG. 29, so that both ends of the outer member137are threadedly engaged with the base135and the cap136. This configuration needs machining of the screw portions, resulting in an increase in cost, but allows easy detachment of the base135and the cap136from the outer member137because both ends of the outer member137are not press-fitted on the base135and the cap136. Thus, those base135, cap136, and outer member137can be reused.

(4) In the above embodiment, all of the inner parts22A,22B,22C and the pistons23,24are resin molded parts, but they may be aluminum die-cast molded parts, lost-wax molded parts, and others which can be manufactured in less cutting works and thus at low costs. When the air-operated valve1A,1B,1C, or1D is to be used for controlling high-temperature control fluid or is to be heated, the temperature of the entire valve may exceed 80° C. In such a case, resin molded parts are inappropriate for the inner parts22A,22B,22C and the pistons23,24. Accordingly, the inner parts22A,22B,22C and the pistons23,24may be made as metal parts such as aluminum die-cast molded parts or lost-wax molded parts to make the air-operated valve1A,1B,1C, or1D usable even in such environments as the temperature of the entire valve is likely to exceed an upper temperature limit, e.g., 80° C.

(5) In the above embodiments, the inner parts22A,22B,22C are identical in shape, but they may be designed having different shapes according to respective mounting places in the outer member21. Specifically, the inner part22B may be designed having thick closed end walls to serve as partition plates for partitioning the first and second piston chambers27,28. On the other hand, the inner parts22A,22C whose closed end walls are supported by the base25and the cap26A,26B, or26C for enhancing the strength may be designed having thin closed end walls. The inner parts22A,22B,22C may be changed in shape according to respective intended use, which can avoid wasteful consumption of materials for the inner parts22A,22B,22C. Further, since unnecessary portions of the inner parts22A,22B,22C are thin as above, the valve can be reduced in size and weight.

(6) In the above embodiments, the outer member21is a metal pipe, but may be a resin molded part. In this case, the outer member21is formed with a large wall thickness for ensuring pressure resistance, which tends to cause an increase in size of the valve. However, such outer member21may be produced easily by injection molding, for example, contributing to a reduction in cost. This also can contribute to a reduction in weight.

(7) In the above embodiments, the branch passages48and56are formed having a rectangular section. The branch passage has only to have a section larger in width in a direction intersecting with (perpendicular to) the main passage than in height in an axial direction to ensure a sufficient passage sectional area. The section of each branch passage48,56may have a horizontally long elliptic shape or a shape defined by a plurality of circles combined in partially superimposed relation in a diameter direction of a piston rod.

(8) In the above third and fourth embodiments, the pistons23and24are provided with the metal parts105and106respectively (seeFIGS. 8,17, and others). As an alternative, the metal part may be attached to only the end of either piston23,24which abuts on the stem13as long as the pistons23,24do not come into contact with other parts.

(9) In the above embodiments, the air-operated valves1A,1B,1C,1D have a cylindrical outer shape, but may have a polygonal outer shape. For this polygonal shape case, the outer member21may be designed to have a polygonal outer surface and a cylindrical inner surface for receiving the inner parts22or to have polygonal outer and inner surfaces if the inner parts22have polygonal outer surfaces. In either case, the outer member21has a pipe shape and thus can be easily produced by cutting out a polygonal pipe made by a drawing or extruding process by a predetermined length.

(10) In the above embodiments, the driving force of the actuator section3A,3B, or3C is transmitted to the diaphragm9through the stem13. As an alternative, the diaphragm9may be placed in direct contact with the end of the piston23or24without interposing the stem13) to directly transmit the driving force to the diaphragm9.

In the above embodiments, the diaphragm9is of a film shape but another diaphragm having a different configuration from the diaphragm9may be adopted. For example, a diaphragm including a main body and a web portion radially extending from the main body may be adopted. In this case, the piston23or24may be coupled to the main body of the diaphragm without a stem.

(11) In the above embodiments, the air-operated valves1A to1D are configured as a two-way valve for selectively allowing and interrupting communication between the primary-side port5and the secondary-side port6. As an alternative, the configurations of the actuators3A,3B,3C described in the above embodiments may be applied to a multiway valve such as a three-way valve. The air-operated valves1A to1D in the above embodiments are diaphragm valves but may be poppet valves.