GB2320311A

GB2320311A - Magnetically latched diverter valves

Info

Publication number: GB2320311A
Application number: GB9625628A
Authority: GB
Inventors: Brian John Cottrell
Original assignee: Appliance Components Ltd
Current assignee: Schneider Electric Controls UK Ltd
Priority date: 1996-12-10
Filing date: 1996-12-10
Publication date: 1998-06-17
Also published as: DE29722208U1; GB9625628D0; FR2756900A1; FR2756900B3

Abstract

A diverter valve (10) controls flow of fluid from an inlet (2) to a common outlet (4), and from an inlet (6) to the common outlet (4). The flow path through the valve (10) is determined by the position of a valve member (8) supported on rod (12) and movable to selectively close first or second valve seats (14,16). Rod (12) is coupled to an actuator (24) which is a dual acting solenoid having first and second coils (30, 32) arranged on either side of an annular permanent magnet (34). A plunger (36) of magnetic material extends axially of the permanent magnet (34) and of the two coils (30, 32). The coils (30, 32) are energised to magnetise the plunger (36) so that it is attracted to, or repelled from, the permanent magnet (34). Movement of the plunger (36) moves the valve member (8) to close a respective one of the valve seats (14, 16). Upon deenergisation of the coils (30, 32) the plunger 36, and hence the valve, is magnetically latched.

Description

1.' A ' 2320311 IMPROVEMENTS IN OR RELATING TO DIVERTER VALVES The present

invention relates to a diverter valve.

Diverter valves control two fluid paths. For example, diverter valves have traditionally been used in central heating systems to divert hot water from the boiler to either the domestic hot water system or to the radiator system as the demand requires.

Increasingly, such diverter valves are being used within the boiler, particularly within combination boilers. This has put new demands on the valve particularly with regard to its cost, its power requirements and its response time.

Presently, diverter valves are generally of the spring return type. With such a design, the actuator of the valve must overcome the force of a spring and provide the closing pressure on one port. When the actuator is de-energised, this spring returns the valve to the other port and provides the closing pressure for that other port. In many designs of spring return valve, power has to be applied continuously to hold the valve in position against the one port against the force of the spring.

The present invention seeks to provide a new diverter valve which reduces the problems of known valves.

According to the present invention there is provided a diverter valve having a valve member movable to close a selected one of two ports, and a magnetically latching bistable actuator arranged to move the valve member between the two ports, wherein said actuator is arranged to magnetically latch in each of two end positions in each of which the valve member closes a respective one of the ports.

In an embodiment of a diverter valve of the invention, the actuator is arranged to magnetically latch in each of its two end positions. This means that the closing force for each port is provided by magnetic forces so no power has to be supplied to the actuator to maintain it in either of its end positions. Furthermore, as the actuator is arranged to move the valve member between the two ports there is no requirement for a spring, and a high integrity of port closure can be obtained at each port.

In a preferred embodiment, the actuator comprises a magnetically latching solenoid arranged to move an elongate drive rod in each of the two opposed directions along its length, movement of the drive rod being arranged to move the valve member.

For example, the drive rod may be connected to the valve member. Alternatively, the drive rod may be coupled to a valve member support.

In a preferred embodiment, the two valve ports are aligned, and the valve member support comprises an elongate support rod carrying the valve member and extending through each of said two valve ports. Thus, movement of the support rod along its length moves the valve member between the two ports.

In a preferred embodiment, the solenoid comprises two coils between which an annular permanent magnet is provided, and a plunger of magnetic material extending axially of the two coils and of the permanent magnet such that the application of dc current to one or both of the coils is effective to move the plunger. This movement of the plunger provides drive for the elongate drive rod.

In one embodiment, the coils are connected to be independently energised with dc power of the same polarity. In an alternative embodiment, the coils are connected to be energised simultaneously, but the polarity of the applied dc is changed in dependence upon the position required for the valve member.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 shows a diverter valve of the present invention, the valve body being shown in section, Figure 2 shows an actuator of the valve of Figure 1, and Figures 3a and 3b illustrate alternative electrical connections, and the power applied, for the actuator of Figure 2.

Figure 1 shows a diverter valve 10 for controlling the flow of fluid through two alternative flow paths. The first flow path is from an inlet 2 to a common outlet 4, and the alternative flow path is from an inlet 6 to the common outlet 4. Of course, it will be appreciated that the diverter valve 10 could alternatively be used with the common port 4 acting as an inlet port, and with the flow of fluid being selectively to the outlet port 2 or to the outlet port 6. The flow path through the valve 10 is determined by the position of a valve member 8. As can be seen, this valve member 8 is supported on an elongate rod 12 and is movable to selectively close a first valve seat 14 or a second valve seat 16. The support rod 12 extends out of the valve housing by way of appropriate sealing means, generally indicated at 20.

At its upper end, the support rod 12 is coupled, by way of a coupling 22, to an actuator 24. In the embodiment illustrated, this actuator 24 is supported on a bracket 26 which is coupled to a housing for the valve 10. The actuator 24 is, as described below, arranged to move the rod 12 upwardly or downwardly along its length whereby the valve member 8 is selectively brought into sealing engagement with a respective one of the valve seats 14 or 16.

A section of the actuator 24 is shown in Figure 2. As can be seen, the actuator 24 is a dual acting solenoid having first and second coils 30 and 32 arranged on either side of an annular permanent magnet 34. A plunger 36 of magnetic material extends axially of the permanent magnet 34 and of the two coils 30 and 32. The plunger 32 is connected to a drive rod 38 which is coupled by way of the coupling 22 to the valve support rod 12. The solenoid coils 30, 32 are mounted within a magnetic frame 40, and at each end there is a respective stop 42. The stops 42 are also of magnetic material and form part of the magnetic path as is indicated by the flux lines shown in Figure 2.

In operation, the coils 30 and 32 are appropriately energised to magnetise the plunger 36 whereby it is attracted to, or repelled from, the permanent magnet 34.

The stops 42 define the end positions for the plunger 36. It will be appreciated that movement of the plunger 36 moves the valve member 8 by way of the drive rod 38 and the support rod 12. In each of the end positions of the plunger 36, the valve member 8 is positioned to close a respective one of the valve seats 14, 16.

The manner of controlling the solenoid can be chosen as required. Two particular ways are indicated in Figures 3a and 3b. Thus, in Figure 3a each of the coils 30 and 32 is, in use, independently energised. Thus, if it is required to move the plunger 36 to the left hand end position, that is, to the position illustrated in Figure 2, a positive pulse of dc is applied to coil 30 for a time T. This dc power is arranged to be powerful enough to move the plunger 36 to the left hand stop 42 so that the plunger 36 is magnetically latched in that end position. The application of dc is then ceased and the magnetic forces retain the plunger 36 in the position indicated. When, in due course, it is wished to move the valve member 8 to the other port, a similar dc pulse of the same power and period is applied to the coil 32 to overcome the magnetic latching forces, move the plunger 36 to the other end stop, and magnetically latch it in position.

An alternative approach is illustrated in Figure 3b.

In this case, the two coils 30 and 32 are energised simultaneously, but the coils are oppositely wound. This means that the dc pulse applied to the two coils causes one of the coils to attract the plunger 36 whilst the other repels it. This also means, as indicated in Figure 3b, that movement of the plunger in the opposite direction requires a dc pulse of the opposite polarity.

It will be appreciated that modifications and variations to the embodiments illustrated may be made within the scope of this application.

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Claims

1. A diverter valve comprising a valve member movable to close a selected one of two ports, and a magnetically latching bistable actuator arranged to move the valve member between the two ports, wherein said actuator is arranged to magnetically latch in each of two end positions in each of which the valve member closes a respective one of the ports.

2. A diverter valve as claimed in Claim 1, wherein the actuator is arranged to io magnetically latch in each of its two end positions.

3. A diverter valve as claimed in Claim 1 or Claim 2, wherein the actuator comprises a magnetically latching solenoid arranged to move an elongate drive rod in each of the two opposed directions along its length, movement of the drive rod being arranged to move the valve member.

4. A diverter valve as claimed in Claim 3, wherein said drive rod is connected to the valve member.

5. A diverter valve as claimed in any preceding claim, wherein the two valve ports are aligned, and the valve member comprises an elongate support rod carrying the valve member and extending through each of said two valve ports such that movement of the support rod along its length moves the valve member between the two ports.

6. A diverter valve as claimed in any preceding claim, wherein said actuator comprises a magnetically latching solenoid having two coils between which an annular permanent magnet is provided, and a plunger of magnetic material extending axially of the two coils and of the permanent magnet such that the application of dc current to one or both of the coils is effective to move the plunger.

7. A diverter valve as claimed in Claim 6, wherein said two coils are connected to be independently energised with dc power of the same polarity.

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8. A diverter valve as claimed in Claim 6, wherein said two coils are connected to be energised simultaneously, but the polarity of the applied dc is changed in dependence upon the position required for the valve members.

9. A diverter valve substantially as hereinbefore described with reference to the accompanying drawings.