GB2061015A

GB2061015A - Direct current solenoid operator

Info

Publication number: GB2061015A
Application number: GB8033418A
Authority: GB
Original assignee: Automatic Switch Co
Current assignee: Automatic Switch Co
Priority date: 1979-10-17
Filing date: 1980-10-16
Publication date: 1981-05-07
Also published as: FR2468192B3; AU6174780A; NL8005600A; CA1155893A; FR2468192A1; JPS5673409A; BR8006549A; DE3039071A1

Abstract

A direct current solenoid operator comprises an annular electrical solenoid winding (28), a non-magnetic core tube (29) within the winding, and a magnetic armature (32) slidable longitudinally within the core tube (29). A magnetic plugnut (38) within the solenoid winding (28), is outside the core tube (29), so that the wall of the core tube (29) is between, and completely separates, the plugnut (38) and armature (32). No separate breaker piece is needed between the armature (32) and plugnut (38), since the core tube (29) prevents intimate contact between the armature (32) and plug nut (38). <IMAGE>

Description

SPECIFICATION Direct current solenoid operator This invention relates to solenoid operators, intended for energization by direct current, such ås those used to open and close valves for controlling the flow of fluids. Although the primary application of this invention is in the field of solenoid-operated valves, the solenoid operator of this invention may be used to control any suitable device.

A conventional direct current solenoid operator includes an annular solenoid winding surrounding a tube, often referred to as a "core tube", made of non-magnetic material. Slidable longitudinally within the core tube is an armature of magnetic material, the armature being exposed through one open end of the core tube. The exposed end of the armature is connected to a valve member or any other element to be controlled by the movement of the armature.

Fixed within the other end portion of the core tube is a magnetic block, often called a "plugnut". Where the core tube is of the type initially open at both ends, the plugnut closes the end of the core tube within which it is located. Alternatively, the core tube may be of the seamless, or deep drawn, type whereby the tube is formed closed at one end, in which case the plugnut is completely enclosed by, and fills, the closed end of the tube. A yoke of magnetic material extends around the solenoid winding, the armature, plugnut, and yoke comprising a magnetic circuit.

When the solenoid is energized by direct current, magnetic flux flowing through the magnetic circuit causes the movable armature to be attracted to the plugnut, thereby moving the armature further into the core tube. Upon deenergization of the solenoid, a spring returns the armature to its original position by moving it away from the plugnut. Since the plugnut retains a residual magnetism after deenergization of the solenoid, there is a tendency for the armature to remain attracted to the plugnut. To deal with this situation, it is commnon practice to furnish the face ofthe plugnutwhich is engaged by the armature with a thin piece of non-magnetic material, usually called a "breaker piece".By preventing intimate contact between the armature and plugnut, the breaker piece greatly reduces the attraction effect between the armature and plugnut due to the residual magnetism in the plugnut. The advantage of this is that a lower spring force is needed to return the armature than would be needed in the absence of a breaker piece. The lower the spring force, the greater the proportion of power pulling the solenoid toward the plugnut, against the spring force, which.

can be used to perform useful work.

It is an object of the present invention to provide a direct current solenoid operator devoid of a breaker piece, but which nevertheless includes the function ordinarily performed by the breaker piece.

It is another object of the invention, where the solenoid operator employs a seamless core tube, to provide a solenoid operator of greater magnetic efficiency by reducing the non-magnetic flux gaps in the magnetic circuit.

It is a further object of the invention to provide a direct current solenoid operator which, when used to operator a packless valve controlling the flow of liquids, has greater magnetic efficiency and is less costly to produce the conventional operators.

These objectives are achieved, according to the invention, by locating the plugnut outside the core tube rather than within it, as is conventional practice.

With the plugnut located outside the core tube, the wall of the core tube serves to permanently separate the plug nut and armature. Hence, the core tube wall serves the function of the usual breaker piece, and the breaker piece can be eliminated. Elimination of the breaker piece not only reduces the cost of the solenoid operator, but it improves magnetic efficiency by removing one flux gap from the magnetic circuit. Ordinarily in such cases, both the core tube wall and the breaker piece create non-magnetic gaps in the magnetic circuit. In the absence of a breaker piece, one of the usual gaps is not present.

In a packless valve, the interior of the core tube communicates with the flow passages through the valve body with the result that the interior of the core tube is filled with the fluid being handled by the valve. Conventionally, therefore, the fluid contacts both the armature and the plugnut, both of which are within the core tube. When a solenoid operator according to the present invention is employed, the plugnut is not contacted by the fluid flowing through the valve, since it is located outside the core tube. As a result, the plugnut may be made of a material which has a higher magnetic permeability, and is less costly, as compared to conventional plugnuts, because resistance to corrosion due to the fluid being handled need not be considered when choosing the material of which the plugnut is made. Thus, magnetic efficiency is increased and cost of manufacture reduced.

Additional objects and features of the invention will be apparent from the following description in which reference is made to the accompanying drawings.

In the drawings: Figure 1 is a top view of a valve provided with a direct current solenoid operator according to the present invention; Figure 2 is a longitudinal cross-sectional view taken on line 2-2 of Figure 1, showing the valve closed; Figure 3 is a fragmentary view of a portion of Figure 2 showing the valve open; and Figure 4 is a view similar to Figure 2, showing another embodiment of the invention.

Operator 15 includes a yoke 18 formed of one piece of magnetic material, e.g., a ferrous metal, bent to the required shape. The yoke has a base 19 presenting two longitudinally projecting ears 20, each ear having an internally threaded hole. By means of two brackets 21, and two machine screws 22 which are threaded into holes in ears 20, yoke 18, and hence the solenoid operator, is secured to valve body 10. The yoke further includes upstanding arms 23 bent upwardly from base 19, and horizontal sections 24 bent inwardly from the upper ends of arms 23. The horizontal sections are of stepped configuration designed so that they mesh, as shown in Figure 1, to form a top wall of the yoke, and each section 24 is formed with a generally semicircular cutout which combine to define a hole 25 in the top wall of the yoke.

Within yoke 18 is an annular electrical solenoid winding 28 provided with conventional means (not shown) for energizing it with direct current power.

Within the solenoid winding is a seamless core tube 29 made of a non-magnetic, usually metallic, material. The core tube extends into the solenoid winding for about half the height of the latter, and is closed at its upper end by an end wall 30 having a frustoconical shape, as shown, or any other suitable shape for optimizing the magnetic characteristics of the arrangement. The lower end of core tube 29 is open and formed with an outwardly directed flange, an O-ring seal 31 being squeezed between the flange and yoke base 19.

Core tube 29 accommodates a longitudinally slidable armature 32 made of magnetic material. At its lower end, armature 32 carries a valve member 33, of resilient material, located within a chamber 34 in the valve body and adapted to cooperate with valve seat 14. A compression spring 35, within chamber 34, constantly urges valve member 33, and hence armature 32 toward valve seat 14.

Seated on the outer surface of core tube top wall 30 is a plugnut 38. The plugnutfills the balance of the interior of solenoid winding 28 not occupied by core tube 29, and projects upwardly beyond the solenoid.

At its upper end, plugnut 38 presents a reduced diameter post 39 fitted within the hole 25 of yoke 18.

Plug nut 38 is squeezed tightly between top wall 30 and yoke sections 24 to insure good contact between sections 24 and the upwardly facing wall of the plugnutsurrounding post 39. It will seen that plugnut 38 is entirely outside core tube 29, and that top wall 30 of the core tube is between and completely separates the plugnut and armature 32.

When solenoid winding 28 is energized by direct current power, magnetic flux flows through the magnetic circuit from yoke base 19, through arms 23, sections 24, plugnut 38, and armature 32, back to base 19. As a result, armature 32 is attracted to plugnut 38, against the force of spring 35, to open the valve, as shown in Figure 3. Fluid flows from inlet port 11, through passageway 40 in the valve body, chamber 34, and orifice 13, to outlet port 12. Upon deenergization of winding 28, spring 35 returns armature 32 downwardly bringing valve member 33 into engagement with seat 14to close the valve, as shown in Figure 2. Throughout the operation of the valve, chamber 34 and the interior of core tube 29 are filled with the fluid being controlled by the valve, since they are in constant communication with inlet port 11 through passageway 40.However, since plugnut 38 is located outside the core tube, the fluid never contacts the plug nut. Hence, there is no possibility of the fluid having a corrosive effect on the plugnut.

It will be seen that no separate breaker piece is employed since top wall 30 of the core tube serves the functon of a breaker piece, i.e., preventing contact between armature 32 and plugnut 38 when solenoid 28 is energized, as shown in Figure 3. As a result, when the solenoid is deenergized, the nonmagnetic gap created by top wall 30 reduces the effect on armature 32 of residual magnetism in plugnut 38. Furthermore, although a seamless core tube 29 is employed, the magnetic circuit is interrupted by only two gaps, one between the plugnut and armature caused by the top wall 30, and one between the armature and yoke base 19 caused by the side wall of core tube 29. In contract, if plugnut 39 were inside core tube 29, a third gap in the magnetic circuit would be created by a required breaker piece between the piugnut and armature.

Another embodiment of the solenoid operator of this invention, applied to a valve, is illustrated in Figure 4. Parts in this figure identical to those of Figures 1-3 bear the same reference numerals as in the earlier figures, and parts generally corresponding to those of Figures 1-3 bear the same reference numerals, followed by a prime, as in the earlier figures. In this form of the invention, the core tube 29' has a reduced diameter portion 43 extending from the core tube portion which accommodates armature 32'. The upper end of portion 43 could be closed, or as shown in Figure 4 is open to define a port 11' of the valve. A slot 44 in armature 32' permits fluid communication between port 11' and chamber 34, the chamber in turn communicating, when the valve is open, with outlet port 12' through orifice 13'.In this embodiment, plugnut 38' is in the form of a hollow sleeve surrounding portion 43 of core tube 29', and which seats on the frusto-conical wall 45 of the core tube. Plugnut 38' is squeezed tightly between wall 45 and yoke sections 24 to insure good contact between the upper end of the plugnut and yoke sections.

As in the previously-described embodiment, plugnut 38' is separated from armature 32' by core tube wall 45, thereby eliminating the need for a separate breaker piece, and plug nut 38' is never contacted by fluid being handled by the valve. The valve of Figure 4 operates in a manner similar to that of the valve of Figures 1-3 in that armature 32' rises to open the valve when solenoid winding 28 is energized, and is returned by spring 35 to close the valve, as shown in Figure 4, when the solenoid is deenergized.

The invention has been shown and described in preferred form only, and by way of example, and many variations may be made in the invention which will still be comprised within its spirit. It is understood, therefore, that the invention is not limited to any specific form or embodiment except insofar as such limitations are included in the appended

Claims

claims. CLAIMS

1. A direct current solenoid operator, comprising: (a) an annular electrical solenoid winding, (b) a non-magnetic core tube within the solenoid winding, (c) a magnetic armature slidable longitudinally within the core tube, and (d) a magnetic plug nut within the solenoid wind ing, the plugnut being outside the core tube so that the wall of the core tube is between, and completely separates, the plugnut and armature.

2. A direct current solenoid operator as defined in Claim 1 which is devoid of a separate nonmagnetic breaker piece between the armature and plugnut, the core tube wall serving to prevent intimate contact between the armature and core tube.

3. A direct current solenoid operator as defined in Claim 1 wherein the top wall of the core tube is closed, and the plugnut is located above the core tube top wall.

4. A direct current solenoid operator as defined in Claim 1 wherein the core tube has a reduced diameter portion extending beyond the portion of the core tube occupied by the armature, and the plugnut is in the form of a hollow sleeve surrounding the reduced diameter portion of the core tube.

5. A direct current solenoid operator as defined in Claim 4 assembled with a valve body, and wherein the free end of the reduced diameter portion of the core tube defines an inlet port for the valve.

6. A direct current solenoid operator as defined in Claim 1 assembled with: (e) a valve body having an orifice surrounded by a valve seat located between an inlet port and an outlet port, and (f) a valve member carried by the armature and movable with the armature into and out of engagement with the valve seat to close and open the valve, respectively.

7. A direct current solenoid operator as defined in Claim 6 wherein the interior of the core tube communicates with the fluid flow path through the valve body, the core tube being between the fluid flow path and the plugnut, thereby preventing the fluid flowing through the valve from contacting the plugnut.

8. A direct current solenoid operator substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings.

9. A direct current solenoid operator substantially as hereinbefore described with reference to and as illustrated in Figure 4 of the accompanying drawings.