Solenoid for solenoid-operated valve

Abstract: Two coil assemblies 2a and 2b each having a coil 6 wound around a bobbin 5, a fixed and a movable iron cores 8 and 11 provided in a center hole 7 of the bobbin 5, and a pair of pin-like coil terminals 9a and 9b protruding from the end surface from the bobbin 5 are integrated into a single magnetic frame sized so as to accommodate two coil assemblies simultaneously, or a single coil assembly 2a and a dummy member 3 having essentially the same external shape and size as the coil assembly are integrated into the magnetic frame. These components are sealed and integrated into a synthetic resin 22.

Description: The present invention relates to a solenoid for a solenoid-operated valve. Solenoid-operated valves that switch a channel for an operating fluid such as compressed air include pilot solenoid-operated valves that use a solenoid-operated pilot valve to operate a transfer valve. Such pilot solenoid-operated valves are classified into a single pilot type with a single pilot valve, and a double pilot type with two pilot valves. In a single-pilot solenoid-operated valve, a force effected by a spring or a pilot fluid is constantly applied to one end of a spool in a transfer valve, and a pilot valve supplies and ejects a pilot fluid to and from a piston at the other end of the spool in order to switch the spool. In a double-pilot solenoid-operated valve, two pilot valves alternately supply and eject a pilot fluid to and from pistons at both ends of a spool in order to switch the spool. Since these single- and double-pilot solenoid- operated valves differ in terms of the number of pilot valves and the method for supplying a pilot fluid to the spool, they have different structures and essentially cannot share the same parts. Nonetheless, with means for allowing one of the two pistons provided at the respective ends of the spool to be an optional component or to change its size or to make the two pistons have different pressure-receiving areas, a transfer valve can be used as both single and double pilot types. Due to the difference in the number of pilot valves, their external shapes are different. However, many users need single- and double-pilot solenoid-operated valves that have the same external shapes. To meet this need, JP2532723 proposes a single-pilot solenoid-operated valve having substantially the same external shape as a double-pilot solenoid-operated valve. In this valve, a single solenoid and a single dummy body with the same shape and size as the solenoid are integrally molded and mounted in the transfer valve. To configure this as a double-pilot solenoid valve, two integrally-molded solenoids are mounted in the transfer valve. Due to the use of two complete molded solenoids that can operate separately, however, the double- pilot solenoid-operated valve has duplicate parts that could otherwise be shared by both solenoids, resulting in the inefficient use of parts. In addition, in both the double- and single-pilot types, the two solenoids or the solenoid and dummy body must be coupled during molding using an exclusive holding member, thereby increasing the number of required parts, which complicates the structure and increases the cost of assembly. It is an object of this invention to provide a simple and economical configuration for selenoid coil assemblies which can be used for single- and double-pilot solenoid-operated valves so that the coil assemblies have substantially the same external shape by arranging for them to share common parts, and so enabling some of the parts to be used for multiple applications. EP-A-0662696 discloses a method for fabricating a molded solenoid device which is encased in an insulating synthetic resin shell, in which a resilient sealing cover member of an electrically insulating material is fitted on each one of a couple of solenoid coil terminals which are projected from a solenoid coil bobbin. The sealing cover members on the respective coil terminals are brought into intimate contact with inner edges of coil terminal escape holes in a mold in which a solenoid assembly is to be molded, thereby forming tight seals around the coil terminals in the coil terminal escape holes while a molten synthetic resin material is being introduced into the mold cavity around the solenoid assembly. FR-A-2352381 describes a solenoid with a circuit board having two external connection points, the elements of the solenoid being encased in isolating material except those which are to be externally accessible. The invention provides a solenoid for a solenoid-operated valve, the solenoid including at least one coil assembly, the coil assembly comprising a coil wound around a bobbin, a fixed and movable iron core provided in a center hole of said bobbin, and a pair of pin-like coil terminals protruding from an end surface of the bobbin, the solenoid further including a single magnetic frame sized so as to accommodate two such coil assemblies simultaneously, the at least one coil assembly being joined to said magnetic frame, a circuit-board mounting stand in direct engagement with an outer face of said magnetic frame from which the coil terminals of the or each coil assembly protrude and both ends of the magnetic frame, a printed-circuit board in electrical communication with the coil terminals and a terminal housing, the printed-circuit board and the terminal housing being mounted on the circuit-board mounting stand, wherein the magnetic frame, coil assembly, circuit-board, mounting stand and terminal housing are sealed and integrated by a synthetic resin. This invention provides a solenoid for a solenoid-operated valve having a single magnetic frame sized so as to accommodate two coil assemblies simultaneously. To configure a double-pilot solenoid, the two coil assemblies are assembled into the magnetic frame and the magnetic frame, and two coil assemblies are then sealed and integrated into a synthetic resin using molds. The magnetic frame is not only shared by the two coil assemblies to form magnetic paths for them but also functions as a holder that holds the coil assemblies in such a way that they are coupled together. Thus, this configuration eliminates the need to provide an individual magnetic frame for each coil assembly and to provide a separate holder. To configure a single-pilot solenoid, a single coil assembly and a single dummy member with the same external shape and size as the coil assembly are integrated into the magnetic frame. The coil assembly and dummy member are then sealed and integrated into a synthetic resin together with the magnetic frame. The magnetic frame also not only forms a magnetic path for the coil assembly but functions as a holder that holds the coil assembly and dummy member. The coil assembly has a coil wound around a bobbin, one fixed and one movable iron core provided in a center hole of the bobbin, a pair of pin-like coil terminals protruding from the end surface of the bobbin. A circuit board mounting stand preferably of a synthetic resin is disposed on the outer surface of the magnetic frame, and a printed circuit board and a terminal housing having a plurality of power- receiving terminals are mounted on the circuit board mounting stand. The power reception terminal and coil terminal are connected via the printed circuit board, and the circuit board mounting stand, printed circuit board, and terminal housing are sealed and integrated into the mold resin together with the magnetic frame and coil assembly. This configuration provides a safe and appropriately insulated solenoid. The other end of the power reception terminal can protrude to the exterior of the solenoid in order to connect a lamp circuit board to the power-reception terminal. According to a more specific embodiment of this invention, the magnetic frame consists of a first U-shaped member and a second member that connects both ends of the first member together. A plurality of positioning protrusions formed at the vertical ends of each coil assembly are engaged with a plurality of engaging portions formed in the first and second members to integrate the coil assembly and dummy member into the magnetic frame. The invention will now be further described by way of example with reference to the accompanying drawings in which: FIG. 1 is a perspective view showing a first embodiment of a solenoid according to this invention. FIG. 2 is a cross sectional view of FIG. 1. FIG. 3 is a perspective view showing the solenoid in FIG. 1 disassembled. FIG. 4 is an electric circuit diagram of the solenoid in FIG. 1. FIG. 5 is a cross sectional view showing a second embodiment of the solenoid according to this invention. FIG. 6 is an electric circuit diagram of the solenoid in FIG. 5. FIG. 7 is a cross sectional view of an example of the implementation of the solenoid according to the first embodiment. FIG. 8 is an electric circuit diagram of the solenoid in FIG. 7. FIGS. 1 to 4 show a first embodiment of a solenoid 1A. The solenoid 1A is shown configured as a single-pilot type, but its external shape is substantially the same as that of the double-pilot type (see FIG. 5). The solenoid 1A comprises a single coil assembly 2a and a single dummy member 3 that are assembled and molded in a single magnetic frame 4 consisting of a magnetic substance so that they are sealed and integrated into a synthetic resin 22. The coil assembly 2a comprises a bobbin 5 around which a coil 6 is wound, a fixed iron core 8 fitted at one end of a center hole 7 in the bobbin 5, a movable iron core 11 movably disposed at the other end of the center hole 7, and a pair of pin-like coil terminals 9a, 9b that protrude from one end surface of the bobbin 5. Three positioning protrusions 5a are provided on a flange at one end of the bobbin 5 in such a way as to be located at the vertexes of a triangle, and two positioning protrusions 5b are provided on a flange at the other end of the bobbin in such a way as to be opposed to the protrusions 5a. In addition, a conical rubber cap 10 is fitted around the coil terminals 9a and 9b. The dummy member 3, which is formed of an appropriate synthetic resin, is shaped like a cylinder that has substantially the same external shape and size as the coil assembly 2. Three positioning protrusions 3a are provided at one axial end of the dummy member 3 in such a way as to be located at the vertexes of a triangle, and two positioning protrusions 3b are provided in such as a way as to be opposed to the protrusions 3a. In addition, a reinforcing rib 3c shaped like a cross is provided inside the dummy member 3. The magnetic frame 4 consists of a first U-shaped member 12 and a second member 13 connecting both ends of the first member. Three engaging portions 12a that engage the three protrusions 5a and 3a formed at the upper ends of the coil assembly 2a and dummy member 3 are formed in the intermediate piece of the first member 12 at positions to which the coil assembly 2a and dummy member 3 are attached, and a plurality of inflow holes 12c that allow the synthetic resin to flow into the magnetic resin 4 during molding are also formed therein. Notches 12b to which the second member 13 is connected are formed at the respective ends of the first member 12. Two through-holes 13c, 13c through which the movable iron core 11 protrudes are provided in the second member 13 at a position at which the coil assembly 2a and dummy member 3 are incorporated, and engaging portions 13a that engage the two positioning protrusions 5b and 3b at the lower end of the coil assembly 2a and dummy member 3 are formed at both axial ends of the second member 13. In addition, protrusions 13b, 13b that engage the notches 12b, 12b are formed at both longitudinal ends of the second member. A circuit-board mounting stand 14 formed of a synthetic resin is disposed on the outer surface of the magnetic frame 4 from which the coil terminals 9a and 9b protrude, and a printed circuit board 15 and a terminal housing 16 having power reception terminals 17a, 17b, 17c, and 17d to which a power- feeding connector is connected are mounted on the circuit-board mounting stand 14. The circuit-board mounting stand 14 formed of an appropriate synthetic resin comprises bent walls 14a, 14a that engage both longitudinal ends of the first member 12 from the exterior in order to determine their mounting positions and bent portions 14b, 14b that engage a width-wise side edge of the first member 12 in order to determine its width-wise mounting position. In addition, the circuit board mounting stand 14 has notches 14c with which the positioning protrusions 5a and 3a at the upper ends of the coil assembly 2a and dummy member 3 are engaged; inflow holes 14d, 14d in communication with the inflow holes 12c, 12c in the top surface of the first member 12; tap holes 14e, 14e used to mount a cover 44; and a hook-like mounting portions 14f to which the terminal housing 16 is attached. The printed circuit board 15 comprises a printed wiring that connects the coil terminals 9a and 9b to each of the power reception terminals 17a to 17d and on which Zener diodes 20, 20 are mounted as controlling electronic parts. The terminal housing 16, which is molded of an insulating material, has engaging portions 16a that in turn engage the mounting portion 14f of the circuit board mounting stand 14 and that are used to mount the housing 16 on the circuit-board mounting stand 14 in the horizontal direction. The L-shaped power reception terminals 17a to 17d each have one end protruding into a socket portion 16b of the terminal housing 16 and the other end protruding to the exterior from the upper end of the solenoid, with four integral rubber caps 10 fitted on the protrusions. As shown in FIG. 4, the power reception terminals 17a and 17b are electrically connected with the coil terminals 9a and 9b via the printed circuit board 15, and the terminal 17c is connected to the Zener diodes 20, 20 mounted on the printed circuit board 15 and connected in series to the power reception terminal 17a. The remaining power reception terminal 17d is free because this is a single pilot embodiment. According to the first embodiment, the coil assembly 2a and dummy member 3 are assembled in the magnetic frame 4 at mutually parallel positions by engaging the positioning protrusions 5a and 3a at the upper ends of the coil assembly and dummy member with the engaging portions 12a of the first member 12 in the magnetic frame 4 and engaging the positioning protrusions 5b and 3b at the lower end with the engaging portions 13a of the second member 13. The engaging portions 16a are then engaged with the mounting portions 14f to assemble the terminal housing 16 onto the circuit board mounting stand 14, and the printed circuit board 15 is installed in the circuit board mounting stand 14 so as to electrically connect the terminals 17a to 17d to the printed wiring on the printed circuit board 15. Then, the circuit-board mounting stand 14 into which these members are integrated is positioned using the bent walls 14a, 14a and bent portions 14b, 14b and is then assembled on the first member 12, and the coil terminals 9a and 9b are electrically connected to the printed wiring on the circuit board 15. After assembly, these components are inserted into appropriate molds (not shown) to mold them integrally using the synthetic resin 22 in order to provide the solenoid 1A. Since the circuit board mounting stand 14 and first member 12 are U-shaped (i.e., both width-wise sides are open) and the inflow holes 14d and 12c are provided in the circuit board mounting stand 14 and first member 12 so that they communicate mutually when the mounting stand and first member are assembled together, these components can be molded easily. FIG. 5 shows a second embodiment of this invention. A solenoid 1B according to the second embodiment has a configuration that can be used for a double-pilot solenoid-operated vale and comprises two coil assemblies 2a and 2b assembled into the single magnetic frame 4 at mutually parallel positions. FIG. 6 is a circuit diagram of the solenoid 1B. The second embodiment essentially has the same configuration as the first embodiment except that a coil assembly 2b is integrated into the magnetic frame 4 instead of the dummy member 3 and except for the related additions and electric connections of electronic parts. According to the second embodiment, the two coil terminals 9a and 9b of the first coil assembly 2a are connected to the power reception terminals 17a and 17b via the printed circuit board 15, and the two coil terminals 9a and 9b of the second coil assembly 2b are connected to the power reception terminals 17d and 17b. Thus, the power reception terminal 17b is connected to both coil terminals 9b, 9b of the two coil assemblies 2a and 2b. In addition, the printed circuit board 15 has two sets of Zener diodes 20, 20 for the two coil assemblies 2a and 2b that are connected between the power reception terminals 17a, 17d and 17c. As shown in each of the embodiments, in the double-pilot solenoid 1B, the single magnetic frame 4 functions not only as a magnetic path formation means common to the two coil assemblies 2a and 2b but also as a holder that holds the two coil assemblies 2a and 2b in such a way that they are coupled. Thus, this configuration eliminates the need to provide an individual magnetic frame for each coil assembly and to provide a separate holder. In addition, as in the solenoid 1A of a single- pilot type, the magnetic frame 4 functions not only as a magnetic path formation means for the coil assembly 2a but also as a holder that holds the two coil assembly 2a and dummy member 3. By determining whether the two coil assemblies 2a and 2b or the coil assembly 2a and dummy member 3 are integrated into the magnetic frame 4, a small number of common parts and molds can be used to form the single-pilot solenoid 1A and the double-pilot solenoid 1B simply and economically. Furthermore, since all components including electric connections are sealed and integrated into the synthetic resin 22, this invention is easy to handle, is appropriately insulated, and is extremely safe. FIGS. 7 and 8 show a single-pilot solenoid- operated valve that uses a single pilot valve 32 having the solenoid 1A according to the first embodiment in order to operated a transfer valve 31. A valve body 34 of the transfer valve 31 comprises a supply port P, output ports A and B, and ejection ports EA and EB all used for compressed air, and valve holes 35 into which these ports open. A valve disc 36 that switches the communication between the two output ports A, B and the supply port P and ejection ports EA, EB is slidably inserted into the valve hole 35 in a gas- tight manner. A first plate 37a, a pilot valve body 38, and the solenoid 1A are mounted on one side of the valve body 34 while a second plate 37b is mounted on the other side, in a gas-tight manner using an appropriate mounting means such as mounting screws. A first piston 39a of a large diameter is slidably inserted into a first piston chamber of a large diameter formed in the first plate 37a, while a second piston 39b of a small diameter formed in the second plate 37b is slidably inserted into a second piston chamber of a small diameter formed in the second plate 37b. The valve disc 36 is pressed by the pistons 39a and 39b to move back and forth in the figure. A lamp circuit board 41 having a lamp 42 is mounted on the solenoid 1A using an approximate means such as screws. The lamp 42 is supplied with power from the terminals 17a to 17c and the printed wiring provided on the lamp circuit board 41 and electrically connected to the terminals, as shown in FIG. 8. A cover 44 that covers the lamp circuit board 41 includes a transparent or semi-transparent window 44a that allows the lighting of the lamp 42, i.e., power supply to the coil 6 to be viewed externally and that is mounted on the solenoid 1A by screwing tap screws 45 into the tap holes 14e. A cover gasket 46 seals the cover 44 and solenoid 1A in a gas-tight manner. A pilot supply valve chamber 48 is formed opposite to the movable iron core 11 in the pilot valve body 38 and a pilot output valve chamber 49 is formed on an extension from the pilot supply valve chamber 48. A pilot supply valve seat 48a and a pilot ejection valve seat 49a are formed in the valve chambers 48 and 49 on a back-to-back basis, and the valve chambers 48 and 49 are in communication with each other via a communication channel 52. A holder 57 mounted at the tip of the movable iron core 11 prevents a pilot supply valve disc 50 that opens and closes the pilot supply valve seat 48a from slipping out from the movable iron core. The pilot supply valve disc 50 and a pilot ejection valve disc 51 that opens and closes the pilot supply valve seat 49a can be integrally moved by a connecting member (not shown) loosely inserted into the communication channel 52. In addition, the pilot supply valve disc 50 is urged in the direction in which the pilot supply valve seat 48a is closed, by a return spring 58 on the movable iron core that is compressed between the second member 13 and the holder 57. The supply port P in the main valve 31 is in communication with the pilot supply valve seat 48a through a pilot supply channel 53a and with the second piston chamber through a pilot supply channel 53b that penetrates the valve body 34. Furthermore, the supply port P is opened at the bottom surface of the pilot valve body 38 through a pilot supply channel 53c. On the other hand, the pilot ejection valve seat 49a is opened at the bottom surface of the pilot valve body 38 through a pilot ejection channel 54 and is in communication with the ejection port EA via the valve hole 35 and the gap between a check seal 36a and a wear ring 36b fitted in the valve disc 36. The check seal 36a allows a pilot fluid to be ejected only if the ejection air pressure of the fluid exceeds the air pressure in the ejection port EA and otherwise shuts off the communication to the ejection port EA. In addition, the pilot output valve chamber 49 is in communication with the first piston chamber through a pilot output channel 55. In the example presented in FIG, the openings in the bottom surface of the pilot valve body 38 extending from the pilot supply channel 53c and pilot ejection channel 54 are each closed by a plug. In FIG. 7, reference numeral 59 designates a manual operation portion that is pressed to moved the pilot valve disc 50 in order to open the pilot supply valve seat 48a. In the transfer valve 30, when power is supplied through the coil 6 in the solenoid 1A, the fixed iron core 8 attracts the movable iron core 11 to cause the pilot supply valve body 50 to open the pilot supply valve seat 48a while causing the pilot ejection valve disc 51 to close the pilot ejection valve seat 49a. Thus, a pilot fluid supplied from the supply port P in the main valve 31 is supplied to the first piston chamber through the pilot supply valve chamber 48, communication channel 52, pilot output valve chamber 49, and pilot output channel 55. Consequently, the difference in diameter between the first piston 39a and the second piston 39b causes the pistons 39a and 39b and valve disc 36 to be moved rightward in the figure, thereby allowing the supply port P and output port A to communicate with each other while allowing the output port B and ejection port EB to communicate with each other. When the power to the coil 6 is turned off, the pilot supply valve disc 50 closes the pilot supply valve seat 48a whereas the pilot ejection valve disc 51 opens the pilot ejection valve seat 49a, causing the pilot fluid in the first piston chamber to be ejected to the exterior through the pilot output channel 55, pilot ejection valve seat 49a, and pilot ejection channel 54. Thus, force applied by the pilot fluid pressure supplied to the second piston chamber causes the pistons 39a and 39b and valve disc 36 to be moved leftward in the figure, thereby allowing the supply port P and output port B to communicate with each other while allowing the output port A and ejection port EA to communicate with each other. Although not specifically shown, a pilot valve 32 in which the solenoid 1B according to the second embodiment is mounted in the pilot valve body 38 into which the two sets of pilot valve mechanisms are integrated can be mounted on the transfer valve 31 in order to obtain a double-pilot solenoid- operated valve.

Claims: A solenoid (1A, 1B) for a solenoid-operated valve, the solenoid including at least one coil assembly (2A. 2B), the coil assembly (2A, 2B) comprising a coil (6) wound around a bobbin (5), a fixed and movable iron core (8, 11) provided in a center hole (7) of said bobbin (5), and a pair of pin-like coil terminals (9a, 9b) protruding from an end surface of the bobbin (5), the solenoid further including a single magnetic frame (4) sized so as to accommodate two such coil assemblies simultaneously, the at least one coil assembly (2A, 2B) being joined to said magnetic frame (4), a circuit-board mounting stand (14) in direct engagement with an outer face of said magnetic frame (4) from which the coil terminals (9a, 9b) of the or each coil assembly (2A, 2B) protrude and both ends of the magnetic frame (4), a printed-circuit board (15) in electrical communication with the coil terminals (9a, 9b) and a terminal housing (16) , the printed-circuit board (15) and the terminal housing (16) being mounted on the circuit-board mounting stand (14), wherein the magnetic frame (4), coil assembly, circuit-board (15), mounting stand (14) and terminal housing (16) are sealed and integrated by a synthetic resin (22). A solenoid as claimed in Claim 1 wherein the mounting stand (14) is formed of a synthetic resin and wherein the terminal housing (16) has a plurality of power reception terminals (17a to 17d) to which a power-feeding connector is connected, the coil terminals (9a, 9b) being connected to one end of the power-receiving terminals (17a to 17d) via said printed circuit board (15). A solenoid as claimed in Claim 2 wherein the other ends of said power reception terminals (17a to 17d) protrude from the solenoid. A solenoid as claimed in any preceding Claim wherein two coil assemblies (2a, 2b) are accommodated in the magnetic frame (4). A solenoid as claimed in Claim 4 wherein said magnetic frame (4) consists of a first U-shaped member (12) and a second member (13) that connects both ends of the first member together and wherein a plurality of positioning protrusions (5a, 5b) formed at the vertical ends of each coil assembly (2a, 2b) are engaged with a plurality of engaging portions (12a, 12b, 13a, 13b) formed in the first and second members (12, 13) to join the two coil assemblies (2a, 2b) to the magnetic frame. A solenoid as claimed in any one of Claims 1 to 3 wherein a single coil assembly (2a) and a dummy member (3) having essentially the same external shape and size as the coil assembly (2a) are accommodated in said magnetic frame (4). A solenoid as claimed in Claim 6 wherein said magnetic frame consists of a first U-shaped member (12) and a second member (13) that connects both ends of the first member together and wherein a plurality of positioning protrusions (3a, 3b, 5a, 5b) formed at the vertical ends of the dummy member (3) and coil assembly (2a) are engaged with a plurality of engaging portions (12a, 12b, 13a, 13b) formed in the first and second members (12, 13) to join the coil assembly (2a) and dummy member (3) to the magnetic frame (4).

Inventors: ISHIKAWA MAKOTO, KANEKO RYUSHIRO, NARITA MASARU, ISHIKAWA, MAKOTO, KANEKO, RYUSHIRO, NARITA, MASARU, Ishikawa, Makoto, c/o SMC Corporation, Kaneko, Ryushiro, c/o SMC Corporation, Narita, Masaru, c/o SMC Corporation
Applicants: SMC CORP, SMC CORPORATION
Application year: 1998
Main classification: H01F5
IPC codes: H01F7, H01F5