Valve equipment

Abstract

To provide a valve device which reduces the weight while inhibiting breakage and thereby enables easy maintenance work.SOLUTION: A valve device 1 includes: a valve body 2 including a valve chamber 12, an inlet 13 and an outlet 14 communicating with the valve chamber 12, and a valve body 30; and an air cylinder 3 which has a cylinder rod 70 connected to the valve body 30 and drives the cylinder rod 70 by air pressure to move the valve body 30 relative to the valve seat 15. The air cylinder 3 includes: a piston 60 provided with the cylinder rod 70; and a cylinder 50 having a cylinder chamber 54 which houses the piston 60. The cylinder 50 includes: a cylindrical cylinder body 51; and two caps 52 which close openings at both sides of the cylinder body 51. The cylinder body 51 is formed of a fiber-reinforced plastic.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a valve device including an air cylinder that is operated by air pressure and a valve body. [Background technology]

[0002] BACKGROUND ART A valve device is known in which a valve that opens and closes a flow path is driven by an air cylinder that operates by air pressure (see, for example, Patent Documents 1 and 2).

[0003] Air cylinders operate by using air pressure to move a piston inside the cylinder, so the cylinder is made of a material with high strength and rigidity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 09-144903 [Patent Document 2] Japanese Patent Publication No. 2022-182185 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional valve devices are heavy, and there is a problem in that it is difficult to perform maintenance work such as removing the valve device to clean it or check its operation.

[0006] Furthermore, the air cylinder must be made of a material that prevents air leakage and is not destroyed by high air pressure, and there is a problem in that it is difficult to easily adopt a light-weight material.

[0007] In view of the above circumstances, the present invention has an object to provide a valve device that is lighter and less likely to break, thereby facilitating maintenance work. [Means for solving the problem]

[0008] An aspect of the present invention that solves the above-mentioned problems is a valve device comprising a valve body including a valve chamber, an inlet portion and an outlet portion that form a flow path communicating with the valve chamber, and a valve disc that is provided in the valve chamber so as to be able to come into contact with and move away from a valve seat provided in the valve chamber, and an air cylinder that has a cylinder rod connected to the valve disc and pneumatically drives the cylinder rod to move the valve disc relative to the valve seat, wherein the air cylinder includes a piston provided with the cylinder rod and a cylinder having a cylinder chamber in which the piston is accommodated, and the cylinder includes a cylindrical cylinder body and two caps that close openings on both sides of the cylinder body, and the cylinder body is made of fiber-reinforced plastic.

[0009] In this aspect, by forming the cylinder body from fiber-reinforced plastic, the cylinder body can be made lighter, making it easier to remove from the fluid processing device and to perform maintenance such as inspection, cleaning, and replacement of consumables. Furthermore, by forming the cylinder body from fiber-reinforced plastic, the rigidity and strength of the cylinder body can be increased, making it possible to prevent the cylinder body from being damaged by the air pressure in the cylinder chamber. Furthermore, corrosion of the cylinder body can be suppressed.

[0010] Preferably, the fiber reinforced plastic is carbon fiber reinforced plastic, which allows the weight of the cylinder body to be reduced and the rigidity and strength to be improved.

[0011] Preferably, the cylinder body and the cap are fixed to each other via a ring, the ring being fixed to the outer periphery of the cap and bonded to the inner periphery of the cylinder body via an adhesive, the outer periphery of the ring bonded to the cylinder body having a tapered surface with a gradually decreasing outer diameter, and the inner periphery of the cylinder body bonded to the ring having a tapered surface with a gradually decreasing inner diameter. By bonding the tapered surfaces, the bonding area between the cylinder body and the ring is increased, improving the bonding strength, preventing the cylinder body and the bonding interface from being damaged by changes in air pressure inside the cylinder chamber, and preventing air leakage from the bonding interface.

[0012] Preferably, the cylinder body and the cap are fixed to each other via a ring, which is fixed to the outer circumferential surface of the cap and bonded to the inner circumferential surface of the cylinder body via an adhesive. This allows the cylinder body and the cap to be firmly fixed to each other via the ring.

[0013] Furthermore, it is preferable that the cylinder body has an extension portion that is bent and extended from the outer peripheral surface of the cap to a surface of the cap facing away from the cylinder chamber, and the inner peripheral surface of the cylinder body and the extension portion are bonded to the cap via an adhesive. According to this, by providing the extension portion and bonding the extension portion to the cap, it is possible to improve the adhesive strength, prevent the cylinder body and the adhesive interface from being damaged by changes in air pressure inside the cylinder chamber, and prevent air leakage from the adhesive interface.

[0014] Furthermore, it is preferable that the cylinder includes a cylindrical ring fixed to the outer peripheral surface of the cap, a first engagement portion provided on the ring, and a second engagement portion provided on the cylinder body and engaging with the first engagement portion, wherein the direction in which the ring and the cap are attached to the cylinder body is defined as a first direction and the opposite direction is defined as a second direction, the first engagement portion is elastically deformable inward, the second engagement portion has a large diameter portion that is part of the cylinder body and has a relatively large inner diameter, and a small diameter portion that is part of the cylinder body, is located closer to the large diameter portion in the second direction and has a relatively smaller inner diameter than the large diameter portion, the small diameter portion has an inner diameter smaller than the outer diameter of the first engagement portion, and the large diameter portion has an inner diameter larger than the outer diameter of the first engagement portion, and the first engagement portion elastically deforms inward to insert through the small diameter portion and is released from elastic deformation to engage with the large diameter portion. In this aspect, by forming the cylinder body from fiber-reinforced plastic, the cylinder body can be made lighter, making it easier to remove from the fluid processing device and to perform maintenance such as inspection, cleaning, and replacement of consumables. Furthermore, by forming the cylinder body from fiber-reinforced plastic, the rigidity and strength of the cylinder body can be increased, making it possible to prevent the cylinder body from being damaged by the air pressure in the cylinder chamber. Furthermore, corrosion of the cylinder body can be suppressed. Furthermore, the ring can be fixed to the cylinder body without using adhesive.

[0015] Furthermore, it is preferable that the first engagement portion is formed by dividing it into a plurality of slits formed from the opening of the ring toward the second direction, and each of the first engagement portions is formed so as to protrude outward from the outer peripheral surface of the ring in the circumferential direction of the ring. Since this configuration makes it easy to deform the first engagement portion inward, it is possible to attach the ring to the cylinder body even more easily.

[0016] Furthermore, it is preferable that the cap has a retaining portion that is a part of the first direction side, and the retaining portion faces the first engaging portion engaged with the large diameter portion and restricts elastic deformation of the first engaging portion. Since the first engaging portion can maintain the state in which it is engaged with the large diameter portion, it is possible to more reliably prevent the ring from coming off the cylinder body.

[0017] Preferably, the first engagement portion has a first tapered surface whose outer diameter gradually decreases in the first direction, and the second engagement portion has a second tapered surface whose inner diameter gradually decreases in the first direction. Therefore, when the ring is advanced in the first direction, the first engagement portion receives a force bending it inward from the second tapered surface. Therefore, when the ring is advanced in the first direction, the first engagement portion bends inward, making it easier to insert the ring into the small diameter portion.

[0018] Furthermore, it is preferable that the inner peripheral surface of the cylinder body and the outer peripheral surface of the ring are bonded with an adhesive, which can more reliably prevent air leakage from the contact interface. [Effects of the Invention]

[0019] The present invention can realize a valve device that is lighter and less susceptible to breakage, making it easier to perform maintenance work. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view showing a valve closed state of a valve device according to a first embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing an open state of a valve device according to a first embodiment of the present invention. [Figure 3] 1 is an enlarged cross-sectional view of a main part of an air cylinder according to a first embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view of an air cylinder according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view of an air cylinder according to a third embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view of an air cylinder according to a fourth embodiment of the present invention. [Figure 7] FIG. 10 is an exploded perspective view of an air cylinder according to a fourth embodiment of the present invention. [Figure 8] FIG. 10 is an enlarged cross-sectional view of a main part of an air cylinder according to a fourth embodiment of the present invention during installation. [Figure 9] FIG. 10 is an enlarged cross-sectional view of a main part of an air cylinder according to a fourth embodiment of the present invention when mounted. [Figure 10] FIG. 10 is an enlarged cross-sectional view of a main part of an air cylinder according to a modified example of the fourth embodiment of the present invention. [Figure 11] FIG. 10 is an enlarged cross-sectional view of a main part of an air cylinder according to a modified example of the fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described in detail below based on embodiments.

[0022] (Embodiment 1) Fig. 1 is a cross-sectional view showing a valve device 1 according to a first embodiment of the present invention in a closed state. Fig. 2 is a view showing a valve device 1 according to a first embodiment of the present invention in an open state. Fig. 3 is an enlarged cross-sectional view of a main part of an air cylinder.

[0023] As shown in Figures 1 and 2, the valve device 1 includes a valve body 2 and an air cylinder 3, and the valve stem portion 32 of the valve body 2 and the cylinder rod 70 of the air cylinder 3 are fixed by a joint rod 4.

[0024] <Valve body> The valve body 2 includes a flow path member 10, a fixing member 20, a valve element 30, and a diaphragm 40.

[0025] The flow path member 10 is a so-called valve body having a flow path 11 provided therein. The flow path 11 includes a valve chamber 12, an inlet portion 13, and an outlet portion 14.

[0026] The valve chamber 12 has a valve port 12a at a portion communicating with the inlet portion 13. The valve port 12a has a tapered inner circumferential surface that is inclined so that the inner diameter gradually decreases toward the inlet portion 13. The tapered inner circumferential surface of this valve port 12a forms a valve seat 15.

[0027] The inlet portion 13 opens to the right side in Fig. 1, and the outlet portion 14 opens to the bottom side in Fig. 1. In other words, the liquid that flows in from the inlet portion 13 is bent at approximately 90 degrees through the valve chamber 12 and flows out from the outlet portion 14. Pipes (not shown) are connected to the inlet portion 13 and the outlet portion 14, respectively.

[0028] An opening 16 that connects the valve chamber 12 to the outside is provided on the opposite side of the flow path member 10 from the inlet portion 13 , and the opening 16 is closed by a fixing member 20 .

[0029] The valve body 30 includes a valve body portion 31 , a valve stem portion 32 , and an abutment portion 33 .

[0030] The valve body 31 is made of a circular plate-like member. A contact portion 33 made of an elastic material such as rubber or elastomer is fixed to the portion of the valve body 31 facing the valve seat 15. The contact portion 33 is provided continuously in the circumferential direction on the surface of the valve body 31 facing the valve seat 15, and the thickness of the contact portion 33 in the radial direction of the valve stem 32 gradually decreases toward the valve seat 15. In other words, the cross section of the contact portion 33 in the radial direction is approximately triangular, with the apex of the triangle facing the valve seat.

[0031] One end of the valve stem 32 is fixed to the valve disc 31. In this embodiment, the valve stem 32 and the valve disc 31 are formed as an integral member. Of course, the valve disc 31 and the valve stem 32 may be separate pieces that are fixed together. The valve stem 32 has an attachment portion 34. The attachment portion 34 is coaxial with the valve stem 32 and protrudes from the valve stem 32 toward the joint rod 4. A thread is cut into the side of the attachment portion 34. Furthermore, the valve stem 32 has a stepped portion 35 where the diameter of a portion on the attachment portion 34 side is reduced.

[0032] The diaphragm 40 is a member made of flexible resin and has a first insertion hole 41 formed in its center. The back plate 42 has a third insertion hole 43 that opens in a stepped shape in its center. The portion of the third insertion hole 43 with a narrower inner diameter is called third insertion hole 43a, and the portion with a wider inner diameter is called third insertion hole 43b. The joint rod 4 is fitted into the third insertion hole 43b of the back plate 42.

[0033] The attachment portion 34 is fastened to the joint rod 4 by being inserted through the first insertion hole 41 and the third insertion hole 43 and screwed into a screw hole 4a provided at one end of the joint rod 4. Furthermore, by screwing the attachment portion 34 into the screw hole 4a of the joint rod 4, the edge of the first insertion hole 41 of the diaphragm 40 is sandwiched between the stepped portion 35 and the back plate 42. Furthermore, the peripheral edge of the diaphragm 40 is sandwiched between the fixing member 20 and the protrusion 17 provided on the flow path member 10. The diaphragm 40 thus sandwiched seals the gap between the opening 16 of the valve chamber 12 and the valve stem 32. In other words, the diaphragm 40 prevents liquid in the valve chamber 12 from leaking from the opening 16 to the outside. Although not specifically shown, it is preferable to provide O-rings between the step portion 35 and the edge of the first insertion hole 41 of the diaphragm 40, and between the fixing member 20 and the protrusion 17, to prevent liquid from leaking to the outside.

[0034] The fixing member 20 includes a second insertion hole 21 through which the joint rod 4 is inserted, and a backplate accommodating portion 22 that communicates with the second insertion hole 21 and has a recessed shape capable of accommodating a backplate 42. The fixing member 20 is fixed to the opening 16 side of the flow path member 10 by a clamp 23 in a state in which the joint rod 4 is inserted into the second insertion hole 21 and the backplate 42 is accommodated in the backplate accommodating portion 22.

[0035] The fixed member 20 also has a fixed portion 25 having a connection space 24 for connecting the joint rod 4 and the cylinder rod 70 of the air cylinder 3. The fixed portion 25 has a fixing opening 26 for connecting a part of the side surface of the connection space 24 to the outside. A fourth insertion hole 27 for inserting the cylinder rod 70 is provided in the side wall of the fixed portion 25 on the air cylinder 3 side.

[0036] The fixing member 20 has a fixing portion 25 fixed to the cap 52 of the air cylinder 3 by a fixing screw 28 .

[0037] 1 and 2 by being driven by an air cylinder 3 connected via a joint rod 4. When the valve element 30 moves to the right as shown in Fig. 1, the valve element 30 closes the valve port 12a with the contact portion 33 in contact with the valve seat 15. This state is called the valve closed state.

[0038] As shown in Figure 2, when the valve element 30 moves leftward, the valve element 30 opens the valve port 12a with the abutment portion 33 separated from the valve seat 15. This state is called the open state. As the valve element 30 moves between the closed state and the open state, the diaphragm 40 flexibly deforms.

[0039] <Air cylinder> The air cylinder 3 includes a cylinder 50, a piston 60, and a cylinder rod 70.

[0040] The cylinder 50 includes a cylinder body 51, two caps 52, and two rings 53. The cylinder body 51 and the caps 52 are fixed together via the rings 53.

[0041] The cylinder body 51 has a cylindrical shape, and in this embodiment, has a cylinder chamber 54 therein. The cylinder body 51 is not limited to a cylindrical shape and may have an elliptical cylindrical shape, for example. The cylinder body 51 is formed of fiber reinforced plastics (FRP). In particular, the cylinder body 51 is preferably formed of carbon fiber reinforced plastics (CFRP) containing carbon fiber as the fiber. Using FRP, particularly CFRP, for the cylinder body 51 can reduce the weight of the cylinder body 51 and increase its rigidity and strength, thereby preventing the cylinder body 51 from being damaged by the air pressure in the cylinder chamber 54. Furthermore, since FRP is not corroded, even if the cylinder body 51 comes into contact with the liquid whose flow rate is controlled by the valve body 2, the cylinder body 51 can be prevented from being damaged by corrosion. The size, content, and other characteristics of the resin material and fiber material that form the base material of the FRP, particularly CFRP, used for the cylinder body 51 may be known materials.

[0042] The two caps 52 close the openings on both the left and right sides of the cylinder body 51. In this embodiment, the cap 52 closing the opening on the left side of the cylinder body 51 in FIGS. 1 and 2 is referred to as the first cap 52A, and the cap 52 closing the opening on the right side of the cylinder body 51, i.e., the opening on the valve body 2 side, is referred to as the second cap 52B. Hereinafter, when there is no need to distinguish between the first cap 52A and the second cap 52B, they will be referred to as cap 52. The first cap 52A and the second cap 52B are caps 52 having the same shape, but inverted. This eliminates the need to separately produce the first cap 52A and the second cap 52B or to manage inventory, thereby reducing costs.

[0043] The cap 52 is made of a circular plate-like member and has a shape in which its thickness gradually decreases toward the periphery. In this embodiment, the cap 52 has a first portion 52a in the center, a second portion 52b that is thinner than the first portion 52a and located outside the first portion 52a, and a third portion 52c that is thinner than the second portion 52b and located outside the second portion 52b. A step is formed on the surface of the cap 52 facing the cylinder chamber 54 due to the difference in thickness between the first portion 52a, the second portion 52b, and the third portion 52c.

[0044] Furthermore, at least two screw holes 52d are formed on the surface of the cap 52 opposite to the cylinder chamber 54. The fixing member 20 is fixed to the screw holes 52d of the second cap 52B via fixing screws 28. The screw holes 52d of the first cap 52A are used to fix a valve head (not shown) with fixing screws. Although not specifically shown, the valve head is a component that houses, in a case, a solenoid valve for switching the flow of compressed air supplied to the cylinder chamber 54, a sensor for detecting the open and closed states of the valve body 2, a display device that displays the operating state of the valve body 2, and electrical components that control the drive of the solenoid valve and the display of the operating state.

[0045] The cap 52 has a small diameter portion 52e with a small outer diameter on the cylinder chamber 54 side, and a large diameter portion 52f with an outer diameter larger than that of the small diameter portion 52e on the opposite side from the cylinder chamber 54. A step is formed between the small diameter portion 52e and the large diameter portion 52f on the outer periphery of the cap 52. A thread is formed on the outer periphery of the small diameter portion 52e.

[0046] The cap 52 is made of a metal such as stainless steel, and is fixed to the cylinder body 51 via an annular ring 53.

[0047] The ring 53 has a threaded inner surface that screws onto the small-diameter portion 52e of the cap 52, and the ring 53 and the cap 52 are fixed by screwing together. As shown in FIG. 3 , the outer circumferential surface of the ring 53 is bonded to the inner circumferential surface of the cylinder body 51 with adhesive 58. The outer circumferential surface of the ring 53 includes a first horizontal surface 53a that is parallel to the axial direction of the cylinder rod 70 and a first tapered surface 53b that is continuous with the first horizontal surface 53a and has an outer diameter that gradually decreases toward the end opposite the cap 52. A protrusion 53c that protrudes outward beyond the first horizontal surface 53a is provided at the end of the first horizontal surface 53a opposite the first tapered surface 53b of the ring 53. When the ring 53 is inserted into the end of the cylinder body 51 to bond the ring 53 to the cylinder body 51 with adhesive 58, the protrusion 53c abuts against the edge of the opening of the cylinder body 51, restricting the insertion of the ring 53 into the cylinder body 51 and positioning it in the insertion direction.

[0048] Meanwhile, the inner circumferential surfaces at both ends of the cylinder body 51 have a recessed shape that conforms to the first horizontal surface 53a and first tapered surface 53b of the ring 53. That is, the inner circumferential surface at the end of the cylinder body 51 is provided with a second horizontal surface 51a that is parallel to the axial direction of the cylinder rod 70 and a second tapered surface 51b whose inner diameter gradually decreases continuous with the second horizontal surface 51a. The first horizontal surface 53a of the ring 53 and the second horizontal surface 51a of the cylinder body 51, and the first tapered surface 53b of the ring 53 and the second tapered surface 51b of the cylinder body 51 are bonded together with an adhesive 58.

[0049] By providing the first tapered surface 53b and the second tapered surface 51b at the adhesive interface between the ring 53 and the cylinder body 51 in this manner, the adhesive area for bonding the cylinder body 51 and the ring 53 is increased, improving adhesive strength, and preventing air in the cylinder chamber 54 from leaking out from between the cylinder body 51 and the ring 53 to the outside. Also, preventing external air from entering the cylinder chamber 54 from between the cylinder body 51 and the ring 53 is also possible. While the adhesive interface between the cylinder body 51 and the ring 53 may be configured with only a horizontal surface, this reduces the adhesive area compared to when the first tapered surface 53b and the second tapered surface 51b are provided. In other words, by providing the first tapered surface 53b and the second tapered surface 51b at the adhesive interface between the cylinder body 51 and the ring 53, the adhesive area is increased and adhesive strength is improved compared to when only a horizontal surface is provided. Of course, the entire bonding surface between the cylinder body 51 and the ring 53 may be formed of the first tapered surface 53b and the second tapered surface 51b without providing the first horizontal surface 53a and the second horizontal surface 51a. Also, the first tapered surface 53b and the second tapered surface 51b may have a cross-sectional shape that is a convex curved surface or a concave curved surface.

[0050] Incidentally, when the ring 53 is bonded to the cylinder body 51, the inner peripheral surface of the cylinder body 51 on the inside of the ring 53 and the inner peripheral surface of the ring 53 are approximately flush with each other. This prevents the O-ring fixed to the outer peripheral surface of the piston 60, which will be described in detail later, from being worn away by steps when it comes into sliding contact with the inner peripheral surfaces of the ring 53 and the cylinder body 51, thereby reducing its lifespan.

[0051] Furthermore, with the cylinder body 51 and the ring 53 bonded together with the adhesive 58, the cap 52 is screwed onto the ring 53. This fixes the cylinder body 51 and the cap 52 via the ring 53. By screwing and fastening the ring 53 and the cap 52 together in this manner, the cap 52 can be easily removed from the cylinder body 51. Therefore, the air cylinder 3 can be easily disassembled to easily perform maintenance such as cleaning the interior and replacing consumables such as O-rings.

[0052] A fifth insertion hole 55 is provided in the center of the cap 52. The cylinder rod 70 is inserted through the fifth insertion hole 55. It is preferable to provide a bushing or an O-ring (not shown) on the inner surface of the fifth insertion hole 55 of the cap 52.

[0053] The cap 52 is also provided with a through-hole 56 that penetrates through the thickness direction. A connection part 57 is fixed to the surface of the cap opposite the cylinder chamber 54, the connection part 57 having a connection port that communicates with the through-hole 56 and that supplies or discharges air to the cylinder chamber 54. An air compressor that supplies air via piping (not shown), a valve device that adjusts the amount of air supplied and exhausted, and the like are attached to the connection part 57. The through-hole 56 is provided in a position that will not get in the way when the fixing member 20, the valve head, and the like are attached to the cap 52, i.e., in the third part 52c in this embodiment.

[0054] The piston 60 is made of a circular plate-like member and is arranged in the cylinder chamber 54 so as to be movable in the axial direction of the cylinder rod 70. A fixing hole 61 that is coaxial with the fifth insertion hole 55 is formed through the center of the piston 60. The cylinder rod 70 is inserted into and fixed to the fixing hole 61 of the piston 60. In other words, the cylinder rod 70 is inserted into the fifth insertion hole 55 of the caps 52 so that both ends of the cylinder rod 70 are located outside the two caps 52.

[0055] The piston 60 includes a fixed portion 62 having a fixing hole 61 formed therein, and a spring receiving portion 63 on the outer side of the fixed portion 62, the spring receiving portion 63 being thinner than the fixed portion.

[0056] The piston 60 has a step formed on the surface facing the first cap 52A due to the difference in thickness between the fixing portion 62 and the spring receiving portion 63. The spring receiving portion 63 has a recess 64 that opens onto the surface facing the first cap 52A. The piston 60 also has a holding portion 65 on its outer circumferential surface that has a recessed shape that opens onto the outer circumferential surface, and an O-ring 66 is held within the holding portion 65. The piston 60 moves while the O-ring 66 held by the holding portion 65 slides against the inner circumferential surface of the cylinder body 51, thereby maintaining airtightness between the two spaces separated by the piston 60 in the cylinder chamber 54.

[0057] A first spring 67 and a second spring 68, each made of a coil spring, are provided between the piston 60 and the first cap 52A. The first spring 67 has an outer diameter smaller than that of the second spring 68, and one end of the first spring 67 abuts against the second portion 52b of the first cap 52A and the other end abuts against the spring receiving portion 63 of the piston 60, thereby urging the piston 60 toward the second cap 52B with respect to the first cap 52A.

[0058] The second spring 68 has an inner diameter larger than that of the first spring 67, and one end abuts against the third portion 52c of the first cap 52A, and the other end abuts against the bottom surface of the recess 64 of the piston 60, thereby urging the piston 60 toward the second cap 52B relative to the first cap 52A. The first spring 67 and the second spring 68 are designed to be less likely to shift in their contact positions due to steps provided in the first cap 52A and the piston 60.

[0059] In such an air cylinder 3, air is supplied to one of the two spaces separated by the piston 60 in the cylinder chamber 54, creating a pressure difference between the two spaces, which causes the piston 60 to move to the left in the figure relative to the cylinder 50 and open the valve.

[0060] Specifically, air is supplied to the cylinder chamber 54 from the connection part 57 of the second cap 52B, and the air inside the cylinder chamber 54 is discharged to the outside from the connection part 57 of the first cap 52A, thereby generating a pressure difference between the two spaces separated by the piston 60 in the cylinder chamber 54, and moving the piston 60 to the left in the figure, i.e., toward the first cap 52A, against the biasing forces of the first spring 67 and the second spring 68. This drives the cylinder rod 70 fixed to the piston 60 leftward, as shown in FIG. 2, and opens the valve body 2.

[0061] Furthermore, by stopping the supply of air from the connection portion 57 of the second cap 52B, the piston 60 moves rightward in the figure, i.e., toward the second cap 52B, due to the biasing forces of the first spring 67 and the second spring 68. As a result, as shown in FIG. 1, the cylinder rod 70 fixed to the piston 60 is driven rightward, closing the valve body 2. In other words, "driving the cylinder rod 70 by air pressure" includes driving the valve body 2 by air pressure to at least one of opening and closing the valve body 2. Note that, in the closed state, air may be supplied from the connection portion 57 of the first cap 52A to increase the pressing force of the valve element 30 against the valve seat 15. This allows the piston 60 to be pressed by air pressure in addition to the biasing forces of the first spring 67 and the second spring 68, thereby pressing the valve element 30 against the valve seat 15 with high pressure and reliably closing the flow path 11.

[0062] The air may be exhausted from the space separated by the piston 60 in the cylinder chamber 54 in such a way that the pressure in the space is always atmospheric pressure due to the movement of the piston 60, but for example, the air may be exhausted by sucking it in through the connection part 57 so that the space becomes negative pressure. By exhausting the air in this way so that the space becomes negative pressure, the piston 60 can be moved with a stronger force.

[0063] As described above, in the valve device 1 of this embodiment, the cylinder body 51 of the air cylinder 3 is made of FRP, which makes it possible to reduce the weight of the air cylinder 3 and the entire valve device 1. This allows the valve device 1 to be easily removed from the device that processes the fluid, facilitating maintenance such as inspection, cleaning, and replacement of consumables of the valve device 1. Furthermore, because the weight of the valve device 1 is small, the valve device 1 can be easily attached to the device that processes the fluid.

[0064] Furthermore, since the cylinder body 51 is made of FRP, the strength and rigidity of the cylinder body 51 can be improved, and the cylinder body 51 can be prevented from being destroyed by changes in the air pressure in the cylinder chamber .

[0065] Furthermore, because the first tapered surface 53b and the second tapered surface 51b of the ring 53 and the cylinder body 51 are bonded with the adhesive 58, the bonding area between the cylinder body 51 and the ring 53 is increased, thereby improving the bonding strength between the ring and the cylinder body. This makes it possible to prevent air from leaking from within the cylinder chamber 54 between the ring 53 and the cylinder body 51, and to prevent air from entering the cylinder chamber 54 from between the ring 53 and the cylinder body 51. This makes it possible to drive the air cylinder 3 with high precision using air pressure, and to control the valve body 2 with high precision.

[0066] (Embodiment 2) 4 is a cross-sectional view of an air cylinder of a valve device according to embodiment 2 of the present invention. Note that the same members as those in the above-described embodiment are given the same reference numerals and redundant explanations will be omitted.

[0067] As shown in FIG. 4, the cylinder 50 of the air cylinder 3 of the valve device 1 of this embodiment includes a cylinder body 51, two caps 52, and two rings 53.

[0068] The outer peripheral surfaces of cylinder body 51 and cap 52 are fixed to the inner peripheral surface of ring 53. Cylinder body 51 and ring 53 are bonded together with adhesive 58. Thread grooves are formed on the outer peripheral surface of cap 52 and the inner peripheral surface of ring 53, and cap 52 and ring 53 are fixed together by screwing them together.

[0069] As in the first embodiment described above, the cylinder body 51 is made of FRP, particularly CFRP. This allows for a reduction in the weight of the cylinder body 51 and therefore the weight of the air cylinder 3. Furthermore, by forming the cylinder body 51 from FRP, particularly CFRP, the rigidity and strength of the cylinder body 51 can be increased, making it possible to prevent the cylinder body 51 from being damaged by the air pressure in the cylinder chamber 54. Corrosion of the cylinder body 51 can also be prevented. Furthermore, by providing the ring 53 on the outside of the cylinder body 51, the ring 53 reinforces the connection portion between the cylinder body 51 and the cap 52, further preventing deformation of the cylinder body 51 and preventing damage to the connection portion between the cylinder body 51 and the cap 52.

[0070] (Embodiment 3) 5 is a cross-sectional view of an air cylinder of a valve device according to a third embodiment of the present invention. Note that the same members as those in the above-described embodiments are given the same reference numerals, and redundant explanations will be omitted.

[0071] As shown in FIG. 5, the cylinder 50 of the air cylinder 3 of the valve device 1 of this embodiment includes a cylinder body 51 and two caps 52.

[0072] The cylinder body 51 is bonded to the outer peripheral surface of the cap 52. The end of the cylinder body 51 on the first cap 52A side is provided with an extension 51c that is bent and extended from the outer peripheral surface of the first cap 52A along the surface facing away from the cylinder chamber 54. The extension 51c is bonded via adhesive 58 to the surface of the first cap 52A facing away from the cylinder chamber 54.

[0073] Since no extension portion 51c is provided at the end of the cylinder body 51 on the second cap 52B side, the piston 60 can be inserted through the opening on the second cap 52B side before the second cap 52B is bonded to the cylinder chamber 54 of the cylinder body 51.

[0074] Even with an air cylinder 3 having such a configuration, the cylinder body 51 can be made of FRP, particularly CFRP, as in the above-mentioned embodiment 1, thereby making it possible to reduce weight while ensuring strength and rigidity, thereby preventing damage and air leakage due to changes in air pressure.

[0075] In this embodiment, the cylinder body 51 is provided with the extension portion 51c, but the present invention is not limited to this, and the cylinder body 51 and the two caps 52 may be bonded together with the adhesive 58 without providing the extension portion 51c. In other words, the air cylinder 3 may be configured such that the structure shown in FIG. 5 in which the cylinder body 51 and the second cap 52B are bonded together with the adhesive 58 is also used in the portion where the cylinder body 51 and the first cap 52A are bonded together.

[0076] (Embodiment 4) Fig. 6 is a cross-sectional view of the air cylinder of the valve device according to the fourth embodiment, Fig. 7 is an exploded perspective view of the air cylinder, Fig. 8 is an enlarged cross-sectional view of the main part of the air cylinder with the ring attached, and Fig. 9 is an enlarged cross-sectional view of the main part of the air cylinder with the ring and cap attached. Although Fig. 9 shows cap 52B, cap 52A has the same configuration. Note that the same components as those in the above-described embodiments are designated by the same reference numerals, and redundant explanations will be omitted.

[0077] The air cylinder 3 of this embodiment differs from the above-described embodiments 1 to 3 in that the cylinder body 100 and the ring 110 are fixed together by an engaging portion rather than by adhesive.

[0078] The cylinder body 100 and the ring 110 are formed in a cylindrical shape as in embodiments 1-3, and the ring 110 is attached so that its outer circumferential surface contacts the inner circumferential surface of the cylinder body 100. The direction in which the ring 110 and the cap 52 are moved to attach to the cylinder body 100 is defined as a first direction. The opposite direction, i.e., the direction in which the ring 110 and the cap 52 are removed from the cylinder body 100, is defined as a second direction.

[0079] The cylinder body 100 has, from the first direction to the second direction, a second engagement portion 102 and a tip portion 103. The second engagement portion 102 is a portion that engages with the first engagement portion 111 of the ring 110, and will be described in detail later. The tip portion 103 is a portion on the tip side (second direction side) of the cylinder body 100, and has a constant inner diameter Di.

[0080] The ring 110 has, from the first direction to the second direction, a first engagement portion 111, a reduced diameter portion 112, and a base end portion 113. The reduced diameter portion 112 is a portion of the ring 110 whose outer diameter decreases from the base end portion 113 toward the first direction. The first engagement portion 111 will be described later. The base end portion 113 is a portion on the base end side (second direction side) of the ring 110, where the outer diameter Do is constant. The inner diameter Di and the outer diameter Do are approximately the same or the inner diameter Di is slightly larger than the outer diameter Do. As in embodiments 1-3, the ring 110 has a thread groove cut on its inner circumferential surface that threads onto the small diameter portion 52e of the cap 52, and the ring 110 and the cap 52, which will be described later, are fixed by threading together.

[0081] As shown in Fig. 7, the ring 110 has a plurality of slits 115 formed from an opening on the tip side (first direction side) toward the second direction. The slits 115 divide the opening on the tip side of the ring 110 into a plurality of sections, each of which serves as a first engagement portion 111. In the example shown in Fig. 7, four slits 115 are formed in the ring 110, and four first engagement portions 111 are formed by dividing the slits 115.

[0082] Furthermore, ring 110 is made of an elastically deformable material such as stainless steel. By forming slits 115 at the opening of ring 110, when a force acts from the outside to the inside of first engagement portion 111, the tip side of first engagement portion 111 is likely to bend inward. When that force is released, first engagement portion 111 returns to its original shape. Hereinafter, the state in which first engagement portion 111 is bent inward due to the application of force will be referred to as the deformed state, and the state in which the force is released and the first engagement portion is in its original shape will be referred to as the normal state.

[0083] The cap 52 is inserted into the inside of the ring 110 and is fixed by screwing it onto the ring 110. As shown in FIG. 9, when the cap 52 is fixed to the ring 110, a portion of the tip side (first direction side) of the cap 52 is referred to as a retaining portion 59. In this state, the retaining portion 59 is located at approximately the same position as the first engagement portion 111. The retaining portion 59 being located at the same position as the first engagement portion 111 means that the retaining portion 59 faces the entire or part of the first engagement portion 111. In the example shown in the same figure, the retaining portion 59 faces (contacts) a part of the first engagement portion. The retaining portion 59 is intended to prevent the first engagement portion 111 from deforming inward, as will be described in detail later.

[0084] The first engagement portions 111 are provided on the outer peripheral surface of the ring 110 and contact the inner peripheral surface of the cylinder body 100. In this embodiment, the first engagement portions 111 are formed in the circumferential direction of the ring 110 so as to protrude from the outer peripheral surface of the ring 110 to the side (toward the inner peripheral surface of the cylinder body 100 in FIG. 9). As described above, the ring 110 is provided with a plurality of first engagement portions 111 divided by slits 115.

[0085] The first engagement portion 111 also has a first tapered surface 121 whose outer diameter L gradually decreases in the first direction. The outer peripheral surface of the ring 110 also has a fourth tapered surface 124 that contacts a second tapered surface 122 (described later). The fourth tapered surface 124 is the inner surface of the reduced diameter portion 112. The first engagement portion 111 also has a non-tapered surface 111a. The non-tapered surface 111a is the portion of the surface facing the cylinder body 100 other than the first tapered surface 121. Here, the non-tapered surface 111a is flat. The portion of the ring 110 with the largest outer diameter (hereinafter referred to as the maximum outer diameter Dr) is the non-tapered surface 111a of the first engagement portion 111.

[0086] The second engagement portion 102 is provided on the cylinder body 100 and engages with the first engagement portion 111. In this embodiment, the second engagement portion 102 has a large diameter portion 104 and a small diameter portion 105.

[0087] Large diameter portion 104 is a part of cylinder body 100, and is a portion having a relatively larger inner diameter than small diameter portion 105. In detail, large diameter portion 104 is composed of gradually increasing portion 104a whose inner diameter gradually increases from the second direction to the first direction, recessed portion 104b that is continuous with gradually decreasing portion 104c and has a constant inner diameter extending in the first direction, and gradually decreasing portion 104c that is continuous with recessed portion 104b and has a gradually decreasing inner diameter extending in the first direction.

[0088] The widest inner diameter of the large diameter portion 104 is referred to as the first inner diameter D1. When the ring 110 is attached to the cylinder body 100 as shown in FIG. 9, the large diameter portion 104 is formed to fit the surface of the first engagement portion 111. In other words, the surfaces of the recessed portion 104b and the gradually tapered portion 104c of the large diameter portion 104 are in contact with the surface of the first engagement portion 111, and the cylinder body 100 is shaped so as not to apply a force that bends the first engagement portion 111 inward. Note that the large diameter portion 104 may not be in contact with the surface of the first engagement portion 111, leaving a slight gap.

[0089] The small diameter portion 105 is a part of the cylinder body 100, is located closer to the second direction than the large diameter portion 104, and has a relatively smaller inner diameter than the large diameter portion 104. In detail, the small diameter portion 105 has a guide portion 105a whose inner diameter gradually decreases from the second direction to the first direction, and a convex portion 105b between the guide portion 105a and the large diameter portion 104. The inner surface of the guide portion 105a is referred to as a second tapered surface 122. The cylinder body 100 also has a third tapered surface 123 that contacts the first tapered surface 121. The third tapered surface 123 is the inner surface of the gradually decreasing portion 104c.

[0090] The smallest inner diameter of the small diameter portion 105 is referred to as the second inner diameter D2. In the example shown in the figure, the inner diameter of the convex portion 105b is the second inner diameter D2. The fact that the inner diameter of the small diameter portion 105 is relatively smaller than that of the large diameter portion 104 means that the second inner diameter D2 is smaller than the first inner diameter D1. As shown in FIG. 8, the second inner diameter D2 of the small diameter portion 105 is an inner diameter that allows the first engagement portion 111 in a deformed state to be inserted therethrough. As shown in FIG. 9, the second inner diameter D2 of the small diameter portion 105 is smaller than the maximum outer diameter Dr, which is the outer diameter of the first engagement portion 111 in a normal state.

[0091] The ring 110 is attached to the cylinder body 100 as follows. As shown in FIG. 8 , first, the first engagement portion 111 of the ring 110 contacts the second tapered surface 122 of the cylinder body 100. The first engagement portion 111 of the ring 110 is deformed inward by the slit 115. Therefore, as the first engagement portion 111 advances in the first direction, a force acts from the outside to the inside by the guide portion 105a, causing the first engagement portion 111 to deform inward. This deformation allows the first engagement portion 111 to move over the small diameter portion 105 (convex portion 105b) and advance in the first direction. The first engagement portion 111 is provided with a first tapered surface 121, and the small diameter portion 105 of the second engagement portion 102 is provided with a second tapered surface 122. Therefore, when the ring 110 advances in the first direction, the first engagement portion 111 receives a force from the second tapered surface 122 bending it inward. Therefore, when the ring 110 is advanced in the first direction, the first engagement portion 111 is bent inward, making it easy to insert the ring 110 into the small diameter portion 105 .

[0092] 9, the first engagement portion 111 is housed inside the large diameter portion 104 of the second engagement portion 102, and the fourth tapered surface 124 of the ring 110 contacts the second tapered surface 122 of the cylinder body 100. When the first engagement portion 111 overcomes the small diameter portion 105 and reaches the large diameter portion 104 in this manner, the force acting on the first engagement portion 111 from the outside to the inside is released, and the first engagement portion 111 returns to its original shape. Next, with the ring 110 attached to the cylinder body 100, the cap 52 is screwed onto the ring 110 to secure it in place.

[0093] When cap 52 is screwed onto ring 110, retaining portion 59, which is the tip of cap 52, is positioned opposite first engagement portion 111. Retaining portion 59 prevents first engagement portion 111 from bending inward. Because first engagement portion 111 cannot bend inward, first engagement portion 111 cannot get over small diameter portion 105 in the second direction, and ring 110 does not come off cylinder body 100.

[0094] Because the cylinder body 100 is made of a material that is difficult to deform, such as CFRP, the weight of the cylinder body 100 is reduced, making it easier to remove from the fluid processing device and to perform maintenance such as inspection, cleaning, and replacement of consumables. Furthermore, by making the cylinder body 100 from fiber-reinforced plastic, the rigidity and strength of the cylinder body can be increased, making it possible to prevent the cylinder body 100 from being destroyed by the air pressure in the cylinder chamber 54.

[0095] Here, the cylinder body 100 is made of carbon fiber such as CFRP, and has such high strength that the opening on the side that receives the ring 110 does not expand in diameter. Therefore, if the first engagement portion 111 does not deform inward, the first engagement portion 111 is prevented from moving in the first direction by the small diameter portion 105, and the ring 110 cannot be attached to the cylinder body 100.

[0096] However, because the first engagement portion 111 of the ring 110 can deform inward due to the slit 115, the first engagement portion 111 can overcome the small diameter portion 105 and be housed in the large diameter portion 104 (engaged with the second engagement portion 102). By attaching the cap 52 to the inside of the ring 110, the retaining portion 59 prevents the first engagement portion 111 from deforming inward. This prevents the first engagement portion 111 from overcoming the small diameter portion 105 even when the ring 110 is moved in the second direction. Therefore, even if the air pressure in the cylinder chamber 54 presses the ring 110 and the cap 52 in the second direction, the state in which the ring 110 and the cap 52 are attached to the cylinder body 100 can be maintained. Even if the cylinder body 100 is made of carbon fiber, which is thus difficult to deform, the cap 52 can be fixed to the cylinder body 100 via the ring 110.

[0097] The ring 110 has slits 115 formed therein, and each of the first engagement portions 111 divided by the slits 115 can be easily bent inward. This makes it easier to fit the ring 110 inside the cylinder body 100.

[0098] 10 and 11, modified examples of the engaging portion will be illustrated. In the fourth embodiment described above, the cylinder body 100 and the ring 110 have first to fourth tapered surfaces, but are not limited to this. As shown in FIG. 10 , the ring 110 has a first engagement portion 111, and the cylinder body 100 has a second engagement portion 102, each of which has a shape without a tapered surface. As in the fourth embodiment, the first engagement portion 111 is elastically deformable inward (toward the bottom in the figure). Even with this configuration, the ring 110 can be attached to the cylinder body 100 with the first engagement portion 111 bent inward, and a cap (not shown) can be attached to the ring 110 to secure them in place. Furthermore, the engagement between the first engagement portion 111 and the second engagement portion 102 prevents the ring 110 from being removed from the cylinder body 100.

[0099] As shown in FIG. 11 , the cylinder body 100 may not have the third tapered surface 123, and the ring 110 may not have the fourth tapered surface 124. Similarly to the fourth embodiment, the first engagement portion 111 is elastically deformable inward (toward the bottom in the figure). Even with this configuration, the ring 110 can be attached to the cylinder body 100 with the first engagement portion 111 bent inward, and a cap (not shown) can be attached to the ring 110 to secure them in place. Furthermore, the engagement between the first engagement portion 111 and the second engagement portion 102 can prevent the ring 110 from being removed from the cylinder body 100.

[0100] Although not specifically shown, the cylinder body 100 may not be provided with the third tapered surface 123, and the ring 110 may be provided with the fourth tapered surface 124, or the cylinder body 100 may be provided with the third tapered surface 123, and the ring 110 may not be provided with the fourth tapered surface 124. In addition, an adhesive may be provided between the inner peripheral surface of the cylinder body 100 and the outer peripheral surface of the ring 110, including the surfaces of the first engagement portion 111 and the second engagement portion 102, as in embodiments 1-3.

[0101] (Other embodiments) Although the embodiments of the present invention have been described above, the basic configuration of the present invention is not limited to those described above.

[0102] For example, in each of the above-described embodiments, the air cylinder 3 is provided with two springs, the first spring 67 and the second spring 68, but the number of springs is not particularly limited to this, and it may be one, or three or more springs may be provided.

[0103] Furthermore, in each of the above-described embodiments, the valve body 2 is closed by the biasing force of the first spring 67 and the second spring 68 and opened by air pressure. However, this is not particularly limited, and the valve body 2 may be opened by the biasing force of the first spring 67 and the second spring 68 and closed by air pressure. In such a configuration, the direction in which the air cylinder 3 is attached to the valve body 2 may be reversed. That is, by having the cylinder rod 70 protrude from the first cap 52A side and connecting the cylinder rod 70 to the joint rod 4 outside the first cap 52A, the valve body 2 can be opened by the biasing force of the first spring 67 and the second spring 68 and closed by air pressure.

[0104] Furthermore, in the air cylinder 3 of each of the above-described embodiments, air is supplied to one of the two spaces separated by the piston 60 in the cylinder chamber 54, and the valve is opened by air pressure, but this is not particularly limited to this, and the air cylinder may be a so-called double-acting air cylinder in which the piston 60 is moved by supplying and discharging air to each of the two spaces separated by the piston 60 in the cylinder chamber 54, without providing the first spring 67 and the second spring 68.

[0105] In the first embodiment described above, the first horizontal surface 53a and the first tapered surface 53b, and the second horizontal surface 51a and the second tapered surface 51b are provided at the adhesive interface between the ring 53 and the cylinder body 51. However, this is not particularly limited to this, and one or more projections that protrude continuously in the circumferential direction may be provided at regular intervals in the axial direction on each of the outer peripheral surface of the ring 53 and the inner peripheral surface of the cylinder body 51. By providing such projections, the adhesive area between the cylinder body 51 and the ring 53 can be increased and the adhesive strength can be improved by an anchor effect.

[0106] In each of the above-described embodiments, the valve body 2 is sealed by the diaphragm 40 to prevent communication between the valve chamber 12 and the opening 16, but this is not particularly limited. For example, without using the diaphragm 40, the valve stem 32 or the joint rod 4 may be sealed with a bushing or an O-ring so as to have a structure similar to that of the cap 52 and cylinder rod 70 of the air cylinder 3.

[0107] Furthermore, in each of the above-described embodiments, the flow path member 10 is so-called L-shaped, in which the inlets and outlets intersect at approximately 90 degrees, but is not limited to this. It may also be so-called T-shaped, in which the flow paths branch off from flow paths arranged in a straight line. Of course, the flow path member 10 may have a shape other than L-shaped or T-shaped. Furthermore, the flow path member 10 may be configured to have one inlet and multiple outlets, and to be able to switch the liquid outlets using a valve element. [Explanation of symbols]

[0108] 1...valve device, 2...valve body, 3...air cylinder, 4...joint rod, 10...flow path member, 11...flow path, 12...valve chamber, 12a...valve port, 13...inlet portion, 14...outlet portion, 15...valve seat, 16...opening, 17...projection portion, 20...fixing member, 21...second insertion hole, 22...back plate accommodating portion, 23...clamp, 24...connection space, 25...fixing portion, 26...for fixing Opening, 27...fourth insertion hole, 28...fixing screw, 30...valve body, 31...valve body portion, 32...valve stem portion, 33...contact portion, 34...mounting portion, 35...step portion, 40...diaphragm, 41...first insertion hole, 42...back plate, 43...third insertion hole, 43a...third insertion hole, 43b...third insertion hole, 50...cylinder, 51, 100...cylinder body, 51a...second horizontal surface, 51b...third 2 tapered surface, 51c...extension portion, 52...cap, 52a...first portion, 52A...first cap, 52b...second portion, 52B...second cap, 52c...third portion, 52d...screw hole, 52e...small diameter portion, 52f...large diameter portion, 53, 110...ring, 53a...first horizontal surface, 53b...first tapered surface, 53c...projection portion, 54...cylinder chamber, 55...fifth insertion hole, 56...through Hole, 57...connecting portion, 58...adhesive, 60...piston, 61...fixing hole, 62...fixing portion, 63...spring receiving portion, 64...recess, 65...retaining portion, 66...O-ring, 67...first spring, 68...second spring, 70...cylinder rod, 102...second engaging portion, 111...first engaging portion, 121...first tapered surface, 122...second tapered surface, 123...third tapered surface, 124...fourth tapered surface

Claims

1. a valve body including a valve chamber, an inlet and an outlet forming a flow path communicating with the valve chamber, and a valve disc provided in the valve chamber so as to be able to come into contact with and separate from a valve seat; an air cylinder having a cylinder rod connected to the valve body, the air cylinder driving the cylinder rod by air pressure to move the valve body relative to the valve seat, The air cylinder is a piston provided with the cylinder rod; a cylinder having a cylinder chamber in which the piston is accommodated; The cylinder includes a cylindrical cylinder body and two caps that close openings on both sides of the cylinder body. The cylinder body is made of fiber reinforced plastic, The cylinder body and the cap are fixed together via a ring, the ring is fixed to the outer periphery of the cap and is bonded to the inner periphery of the cylinder body via an adhesive; The outer peripheral surface of the ring bonded to the cylinder body has a tapered surface whose outer diameter gradually decreases, The inner circumferential surface of the cylinder body bonded to the ring has a tapered surface whose inner diameter gradually decreases. A valve device characterized by:

2. The fiber reinforced plastic is a carbon fiber reinforced plastic.

2. The valve device according to claim 1.

3. the cylinder body has an extension portion that is bent and extended from the outer peripheral surface of the cap to a surface of the cap facing away from the cylinder chamber, The inner circumferential surface of the cylinder body and the extension portion are bonded to the cap via an adhesive.

2. The valve device according to claim 1.

4. A valve body comprising: a valve chamber; an inlet portion and an outlet portion forming a flow path communicating with said valve chamber; and a valve body provided so as to be able to abut against and separate from a valve seat provided in said valve chamber; an air cylinder having a cylinder rod connected to the valve body, the air cylinder driving the cylinder rod by air pressure to move the valve body relative to the valve seat, The air cylinder is a piston provided with the cylinder rod; a cylinder having a cylinder chamber in which the piston is accommodated; The cylinder includes a cylindrical cylinder body and two caps that close openings on both sides of the cylinder body. The cylinder body is made of fiber reinforced plastic, a cylindrical ring fixed to the outer peripheral surface of the cap; a first engagement portion provided on the ring; a second engaging portion provided on the cylinder body and engaging with the first engaging portion, a direction in which the ring and the cap are attached to the cylinder body is defined as a first direction, and a direction opposite to the first direction is defined as a second direction; the first engagement portion is capable of elastically deforming inward, The second engagement portion is a large diameter portion that is a part of the cylinder body and has a relatively large inner diameter; a small diameter portion that is a part of the cylinder body, is located on the second direction side of the large diameter portion, and has an inner diameter that is relatively smaller than that of the large diameter portion; the small diameter portion has an inner diameter smaller than an outer diameter of the first engagement portion, the large diameter portion has an inner diameter larger than an outer diameter of the first engagement portion, the first engaging portion is elastically deformed inward to insert the small diameter portion therethrough, and is released from elastic deformation to engage with the large diameter portion; A valve device characterized by:

5. the first engagement portion is formed by being divided by a plurality of slits formed from an opening of the ring toward the second direction, Each of the first engagement portions is formed to protrude outward from the outer circumferential surface of the ring along the circumferential direction of the ring.

5. The valve device according to claim 4.

6. the cap has a pressing portion that is a part on the first direction side, the pressing portion faces the first engaging portion engaged with the large diameter portion and restricts elastic deformation of the first engaging portion.

6. The valve device according to claim 5.

7. the first engagement portion has a first tapered surface whose outer diameter gradually decreases in a first direction; the second engaging portion has a second tapered surface whose inner diameter gradually decreases in the first direction; 5. The valve device according to claim 4.

8. The inner peripheral surface of the cylinder body and the outer peripheral surface of the ring are bonded with an adhesive. The valve device according to any one of claims 4 to 7.

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