Diaphragm valve with solenoid pilot valve

Abstract: A diaphragm-type solenoid valve has a valve body 3 fixable onto a base, a diaphragm 4 for opening and closing a valve seat 13 provided at an inner end of a second port 12, a plate 5 for forming a driving chamber 14 between the plate 5 and the diaphragm which is sandwiched between the plate 5 and the valve body 3, and a pilot valve 6 for supplying pilot fluid pressure to the driving chamber 14. A disc 20 is enclosed in a portion of the diaphragm facing the port 12, a sealing rib 21 corresponding to the valve seat is provided, and cushion projecting portions 22 and 23 for coming in contact with cushion receiving portions 32 and 33 on the plate 5 are formed behind the portion where the disc 20 is enclosed.

Description: The present invention relates to a diaphragm-type solenoid valve which can be used with various flow path structures by mounting the required number of solenoid valves onto a base and which is suitable for supplying and discharging special medical fluid which must not include foreign matter. A diaphragm-type solenoid valve is well known as a valve which can easily prevent inclusion of foreign matter or the like by independently forming a flow path for fluid. However, because diaphragm-type solenoid valves are generally formed as a single solenoid value, it is difficult to easily connect the solenoid valve so as to obtain various flow path structures. If a diaphragm-type valve is used for fluid which must not include foreign matter or which is toxic, it is necessary to ensure that the diaphragm is not damaged due to fatigue or the like. It is an object of the invention to provide a diaphragm-type solenoid valve which allows a variety of flow path structures to be obtained. It is another object of the invention to provide a diaphragm-type solenoid valve, the diaphragm of which can be prevented from being damaged due to fatigue or the like. JP 11/141727 discloses a diaphragm-type solenoid valve comprising a valve body having a first port and a second port in a mounting face to be mounted to a base, a valve seat mounted in a flow path connecting both the ports, a diaphragm for opening and closing the valve seat, a plate for sandwiching and fixing an outer peripheral portion of the diaphragm between the plate and the valve body, a driving chamber formed between the plate and the diaphragm and separated from the flow path, and a pilot valve disposed on the plate to supply pilot fluid different from the main fluid to the driving chamber. The diaphragm has a central main body portion for opening and closing the valve seat and an elastic support portion surrounding the main body portion. In a valve according to the invention, a disc is encapsulated in the main body portion, a sealing rib for coming in contact with and separating from the valve seat is provided to one face of the main body portion, and a cushion projecting portion for coming in contact with a cushion receiving portion of the plate is formed on a back face of the main body portion. Preferably, diaphragm receiving faces in shapes corresponding to the shape of the elastic support portion are formed on opposed faces of the valve body and the plate facing the elastic support portion of the diaphragm and the elastic support portion comes in contact with the diaphragm receiving faces in opening and closing of the diaphragm to thereby prevent excessive deformation of the diaphragm. It is preferable that the first port is in an annular shape and the second port opens at a centre of the first port. It is preferable that a pilot air supply hole and a pilot exhaust hole communicating with the pilot valve are provided to the mounting face of the body. One of the diaphragm-type solenoid valves may be mounted onto a base having a supply port and an output port for main fluid and each of the first and second ports connected to one of the supply port and the output port to form a valve complex functioning as a two-port valve from the solenoid valve and the base. Alternatively, a diaphragm-type solenoid valve complex may be formed by mounting two or more of the diaphragm-type solenoid valve solenoid valves onto a base having a supply port, at least one output port, and a discharge port for main fluid and connecting the supply port, the output port, and the discharge port to first and second ports of the solenoid valves by a connecting path in the base so that the complex functions as a three-port valve. In one embodiment of the three-port valve, the base has first and second output ports, four diaphragm-type solenoid valves are mounted onto the base, the first ports of the first and second solenoid valves are respectively connected to the supply port, the second ports of the third and fourth solenoid valves are respectively connected to the discharge port, the second port of the first solenoid valve and the first port of the third solenoid valve are connected to the first output port, and the second port of the second solenoid valve and the first port of the fourth solenoid valve are connected to the second output port. With the diaphragm-type solenoid valve described above, because the disc is encapsulated in the main body portion of the diaphragm and the cushion projecting portion for coming in contact with the cushion receiving portion provided on the plate on valve opening is formed behind the main body portion, impact force acting on the diaphragm on valve opening can be absorbed which protects the diaphragm. Furthermore, because the diaphragm receiving faces for preventing excessive deformation of the diaphragm when the diaphragm is pressed by the operating force of the fluid are formed on the faces of the valve body and the plate opposite to the main body portion, excessive deformation is generated nowhere in operation of the diaphragm and the diaphragm can be prevented to the utmost from being damaged due to fatigue or the like. By mounting the diaphragm-type solenoid valve on a base having a flow path connected to the first and second ports, it is possible to form a complex valve having a function of a two-port valve or a three-port valve with the diaphragm-type solenoid valve and the base and so to obtain various flow path structures depending on the flow path provided in the base. The invention will now be further described by way of example only with reference to the accompanying drawings in which FIG. 1 is a sectional view of a first embodiment of a diaphragm-type solenoid valve according to the present invention. FIG. 2 is a bottom view of the diaphragm-type solenoid valve. FIG. 3 is a sectional view of a second embodiment of the diaphragm-type solenoid valve according to the invention. FIG. 4 is a perspective view of an example of a state in which the diaphragm-type solenoid valves of the invention are mounted to a base. FIG. 5 is a fluid circuit diagram showing a connecting state of the diaphragm-type solenoid valves by the base in FIG. 4 by using symbols. FIG. 6 is a perspective view of another example of the state in which the diaphragm-type solenoid valves of the invention are mounted to the base. FIG. 7 is a fluid circuit diagram showing a connecting state of the diaphragm-type solenoid valves by the base in FIG. 6 by using symbols. FIG. 1 shows a first embodiment of a diaphragm-type solenoid valve according to the present invention. The diaphragm-type solenoid valve 1 of the first embodiment is used in a state in which the valve is mounted onto a base 2, and more specifically, a base 2A or 2B which will be described later by means of FIGS. 4 and 6. The solenoid valve 1 includes a valve body 3 having in a mounting face 3a to be fixed to the base a first port 11 and a second port 12 communicating with two flow paths 2a and 2b opening on the base, a valve seat 13 formed at a mouth edge portion of the second port 12 in a flow path connecting both the ports 11 and 12, a diaphragm 4 for opening and closing the valve seat 13, a plate 5 for sandwiching and fixing an outer peripheral portion of the diaphragm 4 between the plate 5 and the valve body 3, a driving chamber 14 formed between the plate 5 and the diaphragm 4 to be separated from the flow path, and a pilot valve 6 disposed on the plate 5 to supply pilot fluid which is different from main fluid to the driving chamber 14. A diaphragm valve main body formed of the valve body 3, the diaphragm 4, and the plate 5 is assembled by seating the diaphragm 4 on the valve body 3, placing the plate 5 on the diaphragm 4, and fastening the plate 5 to the valve body 3. As shown in FIG. 2, the first port 11 is in an annular shape, the second port 12 is provided to a central portion of the first port 11, a peripheral wall of the first port 11 and a peripheral wall of the second port 12 are connected to each other by a plurality of bridges 15 positioned in radial directions, and the valve seat 13 is provided to a periphery of an inner end of the second port 12. However, the valve seat 13 may be provided to the first port 11 side or to inner ends of both the ports 11 and 12. In the mounting face 3a of the valve body 3, a pilot air supply hole 16 and a pilot exhaust hole 17 open outside the first port 11. The diaphragm 4 is made of material having rubber elasticity and has a central main body portion 4a for opening and closing the valve seat 13 and an annular elastic support portion 4b surrounding the main body portion 4a. In the main body portion 4a, a hard disc 20 is encapsulated. The disc 20 is formed to be slightly larger than a diameter of the valve seat 13. A sealing rib 21 is formed on one face of the main body portion 4a to face the valve seat 13 at a peripheral portion of the disc 20 and a cushion projecting portion 22 in a central position and the large number of small cushion projecting portions 23 at a peripheral portion are formed respectively on a back face of the main body portion 4a. The cushion projecting portions 22 and 23 come in contact with cushion receiving portions 32 and 33 provided to the plate 5 in valve opening when the diaphragm 4 separates from the valve body 3 and absorb impact force acting on the diaphragm 4 in valve opening. An inner bottom of an annular groove formed around the protruding cushion receiving portion 32 at the plate 5 is formed as a spring seat 34 and a return spring 35 is disposed between the spring seat 34 and a periphery of the cushion projecting portion 23 of the diaphragm 4. Furthermore, connecting holes 24 and 25 are respectively formed in positions of a periphery of the diaphragm 4 corresponding to the pilot air supply hole 16 and the pilot exhaust hole 17 of the valve body 3. The plate 5 for airtightly sandwiching the diaphragm 4 between the plate 5 and the valve body 3 has a flow path for supplying pilot fluid pressure to the driving chamber 14 by the pilot valve 6 disposed on the plate 5. The flow path is formed of an air supply flow path 36 for connecting the pilot air supply hole 16 provided to the valve body 3 to a supply port 41 of the pilot valve 6, an output flow path 37 for connecting an output port 42 of the pilot valve 6 to the driving chamber 14, and an exhaust flow path 38 for connecting an exhaust port 43 of the pilot valve 6 to the pilot exhaust hole 17 of the valve body 3. The pilot valve 6 has a movable core 47 attracted to a fixed core 46 by energizing a solenoid 45. An exhaust-side valve body 48 provided to the movable core 47 faces a pilot exhaust valve seat provided to the exhaust port 43 and an air supply-side valve body 49 connected to the exhaust-side valve body 48 through a pressing lever (not shown) faces a pilot air supply valve seat provided to the supply port 41. A reference numeral 51 in FIG. 1 designates a manual operation member for use when the movable core 47 does not operate, 52 designates a feeding socket, 53 designates a receiving terminal, and 54 designates a substrate on which electronic parts are placed. Opposed faces of the valve body 3 and the plate 5 facing the elastic support portion 4b of the diaphragm 4 are formed with diaphragm receiving faces 19 and 39 in shapes patterned on a shape of the elastic support portion 4b. When the diaphragm 4 is pushed by operating force of fluid in opening and closing of the diaphragm 4, the elastic support portion 4b comes in contact with the diaphragm receiving faces 19 and 39 to thereby prevent excessive deformation of the diaphragm 4. The diaphragm 4 in FIG. 1 is shown in a state in which the diaphragm 4 is pressed against the diaphragm receiving face 19 of the valve body 3 by fluid pressure in the driving chamber 14 and the diaphragm shown with a chain line in FIG. 3 is shown in a state in which the diaphragm is pressed against the diaphragm receiving face 39 of the plate 5 by fluid pressure on the sides of the first and second ports 11 and 12. In the diaphragm-type solenoid valve 1 having the above structure, when the solenoid 45 of the pilot valve 6 is not energized, the valve seat provided to the exhaust port 43 is closed with the exhaust-side valve body 48 as the movable core 47 is returned by the spring and at the same time, the valve seat provided to the supply port 41 is opened by the air supply-side valve body 49, and pilot fluid pressure from the pilot air supply hole 16 is supplied from the air supply flow path 36 and the supply port 41 through the output port 42 and the output flow path 37 to the driving chamber 14 as shown in FIG. 1. As a result, the diaphragm 4 is pressed toward the valve body 3 by pilot fluid pressure in the driving chamber 14 and biasing force of the return spring 35 to close the valve seat 13 and to close the flow path between the first and second ports. The pilot fluid pressure supplied to and discharged from the driving chamber 14 may be about the same as pressure of main fluid flowing between the first and second ports 11 and 12 or may be higher than the pressure of the main fluid if necessary. On the other hand, when the solenoid 45 is energized, the valve seat provided to the exhaust port 43 is opened by the exhaust-side valve body 48 and at the same time, the valve seat provided to the supply port 41 is closed with the air supply-side valve body 49, the pilot fluid pressure in the driving chamber 14 is introduced from the output flow path 37 and the output port 42 through a periphery of the pressing lever into a valve chamber where the exhaust-side valve body 48 exists and discharged outside from the valve seat provided to the exhaust port 43 through the exhaust flow path 38 and the pilot exhaust hole 17. As a result, the fluid pressure of the main fluid of the first or second port 11 or 12 presses the diaphragm 4 toward the driving chamber 14 against the biasing force of the return spring 35 to open the valve seat 13 and to open the flow path between the first and second ports. Because the driving chamber 14 and the flow path for the main fluid between the first and second ports 11 and 12 are separated by the diaphragm 4, the diaphragm-type solenoid valve can be applied to medical main fluid or other various main fluid. Because the disc 20 is encapsulated in the main body portion 4a for opening and closing the valve seat 13 at a center of the diaphragm 4 and the cushion projecting portions 22 and 23 for coming in contact with the cushion receiving portions 32 and 33 provided to the plate 5 in valve opening are formed on the back face of the main body portion 4a, impact force acting on the diaphragm 4 in valve opening can be absorbed to protect the diaphragm 4. Furthermore, because the diaphragm receiving faces 19 and 39 are formed at the valve body 3 and the plate 5 such that the elastic support portion 4b comes in contact with and is supported by the diaphragm receiving faces 19 and 39 in opening and closing of the diaphragm 4, excessive deformation is generated nowhere in operation of the diaphragm 4 and the diaphragm 4 can be prevented to the utmost from being damaged due to fatigue. FIG. 3 shows a second embodiment of the diaphragm-type solenoid valve according to the invention. The second embodiment is different from the first embodiment in that the diaphragm 4 is not provided with the return spring 35. In the second embodiment, unlike the first embodiment, the diaphragm 4 is pressed toward the valve body 3 by only operating force of the pilot fluid in the driving chamber 14. Therefore, in order to close the valve seat 13 to reliably close the flow path between the first and second ports, it is preferable that pressure of pilot fluid supplied to the driving chamber 14 is higher than pressure of main fluid flowing between the first and second ports 11 and 12. Because there is no difference in other structures and operation between the second embodiment and the first embodiment, main portions in the drawing are provided with the same reference numerals as those in the first embodiment to omit description of them. FIG. 4 shows a state in which a plurality of diaphragm-type solenoid valves 1A to 1D are mounted onto a base 2A having a supply port P, output ports A and B, and a discharge port E to form a diaphragm-type solenoid valve complex body having a function of a three-port valve from the solenoid valves 1A to 1D and the base 2A and FIG. 5 shows a state in which the respective ports and the solenoid valves 1A to 1D are connected through connecting paths in the base 2A by using symbols. In other words, in positions corresponding to the respective solenoid valves 1A to 1D on a solenoid valve mounting face of the base 2A, openings communicating with the respective ports P, A, B, and E are provided while being connected to have special relationships through the connecting paths in the base 2A, though the openings are not especially shown in the drawings. If the solenoid valves 1A to 1D are mounted to the mounting face, the first and second ports 11 and 12 of the respective solenoid valves are connected to the respective openings. Specifically, as shown in FIG. 5, the first ports 11 of the first and second solenoid valves 1A and 1B are respectively connected to the supply port P, the second ports 12 of the third and fourth solenoid valves 1C and 1D are respectively connected to the discharge port E, the second port 12 of the first solenoid valve 1A and the first port 11 of the third solenoid valve 1C are connected to the first output port A, and the second port 12 of the second solenoid valve 1B and the first port 11 of the fourth solenoid valve 1D are connected to the second output port B. Therefore, the first and second solenoid valves 1A and 1B respectively have functions of supplying or not supplying fluid from the supply port P to the output ports A and B and the third and fourth solenoid valves 1C and 1D respectively have functions of discharging or not discharging fluid of the output ports A and B. The base 2A is formed with a supply port and a discharge port for pilot fluid, openings communicating with the respective ports are formed on the solenoid valve mounting face, and the openings are connected to the pilot air supply holes 16 and the pilot exhaust holes 17 of the respective solenoid valves. FIG. 6 shows a state in which a plurality of diaphragm-type solenoid valves 1A to 1D are mounted onto another base 2B and FIG. 7 shows a state in which the respective ports provided to the base 2B and the solenoid valves 1A to 1D are connected through connecting paths in the base 2B by using symbols. A structure shown in FIG. 6 is different only in that the base 2B has solenoid mounting faces on its two opposed faces and has two solenoid valves on each face and that the supply port P and the discharge port E separately open in the two opposed faces of the base and the structure in FIG. 6 is substantially the same as that in FIG. 4 in relationships of connection between the respective ports P, A, B, and E on the base 2B and the first and second ports 11 and 12 in the respective solenoid valves 1A to 1D. Besides the examples in FIGS. 4 and 6, it is also possible to mount two diaphragm-type solenoid valves on a base having a supply port P, one output port A, and a discharge port E to form a diaphragm-type solenoid valve complex body having a function of a three-port valve or it is possible to mount one diaphragm-type solenoid valve on a base having two ports to form a diaphragm-type solenoid valve complex body having a function of a two-port valve. As set out above, with a diaphragm-type solenoid valve having the above described structure, it is possible to mount a single diaphragm-type solenoid valve or a combination of a plurality of diaphragm-type solenoid valves on a base having a flow path to form a diaphragm-type solenoid valve complex body having a function of a two-port valve, a three-port valve or other arbitrary functions according to the flow path formed in the base. Depending on the flow path provided in the base, it is possible to produce various flow path structures. With the diaphragm-type solenoid valve described above in detail, it is therefore possible to obtain various flow path structures by mounting the valve bodies of the required number of diaphragm-type solenoid valves to a base having a flow path. Furthermore, with the diaphragm-type solenoid valve, neither a sliding portion nor excessive deformation are generated in operation of the diaphragm and the diaphragm can be prevented from being damaged due to fatigue or the like.

Claims: A diaphragm-type solenoid valve (1) comprising a valve body (3) having a first port (11) and a second port (12) for main fluid in a mounting face (3a) to be mounted to a base (2A, 2B), a valve seat (13) in a flow path connecting the ports (11,12), a diaphragm (4) for opening and closing the valve seat (13), a plate (5), an outer peripheral portion of the diaphragm (4) being held between the plate (5) and the valve body (3) and a driving chamber (14) being formed between the plate (5) and the diaphragm (4) and separated from the flow path, and a pilot valve (6) disposed on the plate (5) to supply pilot fluid to the driving chamber (14), wherein the diaphragm has a central main body portion (4a) for opening and closing the valve seat (13) and an elastic support portion (4b) surrounding the main body portion (4a), characterised in that a disc (20) is contained in the main body portion (4a), a sealing rib (21) for coming in contact with and separating from the valve seat (13) is provided on the front of the main body portion (4a), and a cushion projecting portion (22,23) for coming in contact with a cushion receiving portion (32, 33) of the plate (5) is formed on the back face of the main body portion (4a). A diaphragm-type solenoid valve as claimed in Claim 1 wherein the faces of the valve body (3) and the plate (5) facing the elastic support portion (4b) of the diaphragm are formed with diaphragm receiving faces (19, 39) of corresponding shape to the shape of the elastic support portion (4b) and the elastic support portion (4b) comes in contact with the diaphragm receiving faces (19, 39) on opening and closing of the diaphragm. A diaphragm-type solenoid valve as claimed in either Claim 1 or Claim 2, wherein the first port (11) is annular and the second port (12) opens at a centre of the first port. A diaphragm-type solenoid valve, as claimed in any preceding Claim, wherein a pilot air supply hole (16) and a pilot exhaust hole (17) communicating with the pilot valve (6) are provided in the mounting face (3a) of the valve body. A diaphragm-type solenoid valve construction formed by mounting one diaphragm-type solenoid valve (1) as claimed in any preceding Claim onto a base having a supply port and an output port for main fluid and connecting each of said first and second ports (11, 12) to one of the supply port and the output port. A diaphragm-type solenoid valve construction formed by mounting at least two diaphragm-type solenoid valves (1) as claimed in any one of Claims 1 to 4 onto a base (2A, 2B) having a supply port (P), at least one output port (A, B), and a discharge port (E) for main fluid and connecting the supply port, the output port, and the discharge port to first and second ports (11, 12) of the solenoid valves by at least one connecting path in the base. A diaphragm-type solenoid valve construction as claimed in Claim 6, wherein the base has first and second two output ports (A, B), four diaphragm-type solenoid valves (1) are mounted onto the base, the first ports (11) of first and second of the solenoid valves (1A, 1B) are respectively connected to the supply port (P), the second ports (12) of third and fourth of the solenoid valves (1C, 1D) are respectively connected to the discharge port (E), the second port (11) of said first solenoid valve (1 A) and the first port (11) of the third solenoid valve (1C) are connected to the first output port (A), and the second port (12) of the second solenoid valve (1 B) and the first port (11) of the fourth solenoid valve (1 D) are connected to the second output port (B).

Inventors: DICKMAN ROBERT WILLIAM, YOSHIMURA SHINICHI, DICKMAN, ROBERT WILLIAM, YOSHIMURA, SHINICHI, Dickman, Robert William, c/o SMC Corporation, Yoshimura, Shinichi, c/o SMC Corporation
Applicants: SMC CORP, SMC CORPORATION
Application year: 2001
Main classification: F16K31
IPC codes: F16K31, F16K27, F16K7