GB2165923A - Solenoid valve - Google Patents

Abstract

A solenoid valve comprises a valve section 1 having a plurality of ports 2,3, a passage which brings the ports into communication with each other and a valve disc 14a which opens and closes a valve seat 5a in said passage, and a solenoid operating section 20 for actuating said valve disc and including a bobbin 7 having a central passage receiving a fixed core 10 and a movable core 14 and an exciting coil 6 wound around the bobbin, which said solenoid valve further comprises a first recess set in that surface of the valve section which faces the solenoid operating section and a second recess 8b set in the edge of the central passage of the bobbin, the two recesses facing each other and being substantially oppositely disposed, and a magnetic plate 12 which is in contact with said surface of the valve section facing the solenoid operating section and which constitutes part of a magnetic frame, the magnetic plate having a central hole which is substantially coaxial with the central passage of the bobbin and cylindrical projections 13a, 13b protruding from both its faces around said central hole and received within the recesses in the bobbin and valve section, respectively, to position the valve and solenoid operating sections together, the inner surface of said cylindrical projections serving as a surface along which the movable iron core 64 is guided. Further projections may be provided at the outer periphery of the plate 12 for engagement with corresponding recesses in the bobbin 7 and the valve section. <IMAGE>

Description

SPECIFICATION Solenoid valve This invention relates to a solenoid valve which is useful with industrial machines operated by hydraulic pressure or vacuum.

In conventional solenoid valves, such as that described in U.S. Patent No. 3510814, a guide tube of non-magnetic material is surrounded by an exciting coil, there being a yoke of magnetic material around the exciting coil, and a member connecting them to a valve section. The guide tube positions the solenoid operating section with respect to the valve section when they are put together and also guides a movable armature inserted therein.

The convention solenoid valves of the above type have many shortcomings. They are made up of so many component parts that they require much time and work to assemble. Since their magnetic circuit is separated by the tube of non-magnetic material interposed between the yoke and movable armature, magnetic efficiency is too low to permit effective power saving in the solenoid operator. All this has resulted in a difficulty in achieving desired reductions in the size of the solenoid operating section.

This invention has been made with the aforementioned probiems in mind.

The invention generally provides a solenoid valve which has a magnetic plate of special structure in its solenoid operating section, the magnetic plate being adapted to determine the relative position of the valve section and solenoid operating section in assembling, thereby permitting elimination of a special guide tube, enhancing magnetic efficiency by reducing magnetic resistance in the magnetic circuit of the solenoid operating section, and, as a consequence, permitting power saving and size reduction in the solenoid operating section.

More specifically, the present invention provides a solenoid valve comprising a valve section having a plurality of ports, a passage which brings the ports into communication with each other and a valve disc which opens and closes a valve seat in said passage, and a solenoid operating section for actuating said valve disc and including a bobbin having a central passage receiving a fixed core and a movable core and an exciting coil wound around the bobbin, wherein said solenoid valve further comprises a first recess set in that surface of the valve section which faces the solenoid operating section and a second recess set in the edge of the central passage of the bobbin in the solenoid operating section, the two recesses facing each other and being substantially coaxially disposed, and a magnetic plate which is in contact with said surface of the valve section facing the solenoid operating section and which constitutes part of a magnetic frame, the magnetic plate having a central hole which is substantially coaxial with the central passage of the bobbin and cylindrical projections protruding from both its faces around said central hole and received within the recesses in the bobbin and valve section, respectively, to position the valve and solenoid operating sections together, the inner surface of said cylindrical projections serving as a surface along which the movable iron core is guided.

In a solenoid valve of this invention, the valve section and solenoid operating section are assembled together by means of the cylin drical projections protruding from the edge of the central hole on both sides of the magnetic plate which makes up part of the solenoid operating section. As such, the central hole of the solenoid operating section and the valve section can be readily put into proper position by means of the magnetic plate, without requiring any additional parts for that purpose.

The result is fewer parts, easier assembly and lower cost than with the conventional solenoid valves employing guide tubes.

Also, the movable core is now guided directly by the inner surface of these cylindrical projections, without employing the guide tube of non-magnetic material which has previously been needed. This avoids the separation of the magnetic circuit in the solenoid operating section by the guide tube of non-magnetic material and, on the other hand, increases the area in which the movable core is faced. All this lowers the magnetic resistance in the magnetic circuit, reduces magnetic losses, permits power saving in the solenoid operating section and size reduction of the solenoid valve.

Preferred embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a vertical cross-sectional front view of a first preferred embodiment of this invention; Figures 2 and 3 are vertical cross-sectional front views showing a principal portion of two other preferred embodiments; Figure 4 is a plan view of a magnetic plate in another preferred embodiment; and Figure 5 is a perspective view of a magnetic plate in still another preferred embodiment.

Fig. 1 shows a first preferred embodiment of this invention, in which a valve section, generally designated 1, has an inlet 2, an outlet 3, and a recess 4 provided in that surface thereof which faces a solenoid operating section (to be described later) thereby forming a valve chamber 5. The inlet 2 communicates with an opening in a valve seat 5a provided in the valve chamber 5 and the outlet 3 communicates with the valve chamber 5, both through a passage in the valve section 1. The valve chamber 5 in the valve body 1 has a groove on the outside thereof in which a sealing O-ring is fitted.

The solenoid operator has a generally cylindrical bobbin 7 of non-magnetic material around which an exciting coil 6 is wound. The bobbin 7, in turn, has a central passage 8 whose ends are enlarged in diameter to form a holding step 8a and a recess 8b, respectively. The holding step 8a positions the upper end of a stationary core 10 within the central passage 8 and the core 10 is securely held in place by a sealing ring fitted around is end within the holding step 8a.

An annular magnetic plate 12, kept in contact with that surface of the bobbin 7 which faces the valve body 1 (the lower surface as seen in Fig. 1), has on both sides thereof cylindrical projections 1 3a and 1 3b formed around the edge of a central hold 13, which has substantially the same diameter as the central passage 8 of said bobbin, and extending perpendicualr to the magnetic plate 12. By fitting the upper porjection 1 3a (as seen in Fig. 1) in the recess 8b in the bobbin 7, the plate 12 is positioned on the bobbin with its central hole 13 in alignment with the passage 8 of the bobbin 7.

A movable core 14 provided with a valve disc 14a at its lower end (as seen in Fig. 1) to open and close the valve seat 5a is slidably inserted into the central passage 8 and the central hole 13 of the magnetic plate 12 which are coaxially disposed, with the hole 13 serving as a guide. The movable core 14 is urged in the direction in which the valve disc 14a closes the valve seat 5a at all times by a valve spring 15 placed between a recess formed at the other end of the movable core 14 and an opposing recess formed on the stationary core 10.

A cup-shaped magnetic frame 16 covering the bobbin 7 is mounted on the magnetic plate 12, with the inner surface of the open end of the magnetic frame 16 hermetically fitted around the periphery of the magnetic plate 12. The magnetic frame 16, exciting coil 6, stationary core 10, movable core 14 and magnetic plate 12 make up a solenoid operating section which is generally designated 20.

The solenoid operating section 20 is coaxially disposed with the valve section 1 by inserting the cylindrical projection 1 3b of the magnetic plate 12 into the recess 4 defining the valve chamber. The valve section 1 and solenoid operating section 20 thus positioned are joined together as by the use of bolts or other suitable means (not shown).

Fig. 2 shows a part of a second preferred embodiment of this invention which is generally similar to the embodiment of Fig. 1. As shown in Fig. 2 a magnetic plate 12a has a second projection 17 around the periphery thereof which protrudes in the same direction as the cylindrical projection 13a of the magnetic plate 12 of the embodiment of Fig. 1.

The magnetic frame 16 is fitted around the second projection 17.

Fig. 3 shows a part of a third embodiment which is similar to that of Fig. 1, and in which a magnetic plate 1 2b has second projections 17a and 17b on the upper and lower faces at the periphery thereof, respectively, with the projection 1 7b fitted in a recess provided around the periphery of the valve section 1.

The magnetic plates 1 2a and 1 2b of the second and third embodiments serve to increase the area in which the magnetic plates 1 2a and 1 2b are contact with the magnetic frame 16, thereby reducing the magnetic loss in this area.

The valve body 1 and solenoid operating section 20 may be either square or circular in cross-sectional shape, for example. Thus, the magnetic plates 12, 12a and 12b may have a square shape as illustrated in Fig. 4 or a circular shape as illustrated in Fig. 5, depending on the cross-sectional shape of the valve body 1.

The cylindrical projections 13a and 13b and the second projections 17, 17a, and 17b may be integrally press-formed with the magnetic plates 12, 12a and 12b.

The above-described preferred embodiments are two-port valves in which the recess 4 in the valve body 1 serves as the valve chamber 5. However, the recess 4 and valve chamber 5 alternatively may be provided separately.

Also, this invention is not limited to two-port valves but is also applicable to three-port valves in which a further valve seat is provided to the stationary core so that valve discs each facing the two valve seats open and close them alternately.

It necessary, the inner surface of the center hole 13 of the magnetic plates 12, 1 2a and 12b may be covered with a thin film of plating or coating of non-magnetic or weak-magnetic material to prevent abrasive-wear and localized adsorption. Such plating or coating enhances the abrasion resistance and reduces the localized contact and ensuing wear that might occur if the movable core were adsorbed in any biased manner. The thickness of the plating or coating is suitably approximately 50 ,lim and, of course, much thinner than in the case where a conventional guide tube is used.

Claims (6)

1. A solenoid valve comprising a valve section having a plurality of ports, a passage which brings the ports into communication with each other and a valve disc which opens and closes a valve seat in said passage, and a solenoid operating section for actuating said valve disc and including a bobbin having a central passage receiving a fixed core and a movable core and an exciting coil wound around the bobbin, which said solenoid valve further comprises a first recess set in that surface of the valve section which faces the solenoid operating section and a second recess set in the edge of the central passage of the bobbin in the solenoid operating section, the two recesses facing each other and being substantially disposed, and a magnetic plate which is in contact with said surface of the valve section facing the solenoid operating section and which constitutes part of a magnetic frame, the magnetic plate having a central hole which is substantially coaxial with the central passage of the bobbin and cylindrical projections protruding from both its faces around said central hole and received within the recesses in the bobbin and valve section, respectively, to position the valve and solenoid operating sections together, the inner surface of said cylindrical projections serving as a surface along which the movable core is guided.

2. A solenoid valve according to Claim 1, wherein a projection is provided around the periphery of said magnetic plate to contact the periphery of the magnetic frame and thereby increase the area in which the magnetic plate faces the magnetic frame.

3. A solenoid valve according to Claim 2, in which said peripheral projection is provided on the upper side of the magnetic plate.

4. A solenoid valve according to Claim 2, in which peripheral projections are provided both on the upper and lower sides of the magnetic plate, the peripheral projection of the lower side of the magnetic plate being received in a recess provided along the periphery of the valve section.

5. A solenoid valve according to any preceding claim, in which the inner surface of the central hole of the magnetic plate is covered with a thin film of plating or coating of nonmagnetic or weak-magnetic material to reduce abrasive-wear and localized adsorption.

6. A solenoid valve substantially as hereinbefore described with reference to Fig. 1, Fig.

2, Fig. 3, Fig. 4 or Fig. 5 of the accompanying drawings.