GB1559373A

GB1559373A - Magnetic actuators for spool and sleeve valves

Info

Publication number: GB1559373A
Application number: GB4179175A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1975-10-13
Filing date: 1975-10-13
Publication date: 1980-01-16

Description

(54) IMPROVEMENTS IN AND RELATING TO MAGNETIC ACTUATORS FOR SPOOL AND SLEEVE VALVES (71) I, JOHN CHARLES HUM PHREYS HART, a British subiect of Riverside Cottage, Trochry, Near Dunkeld, Perthshire (formerly of Waterfield, Baslow Road, Bakewell, Derbyshire) do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to magnetic actuators for spool and sleeve valves.

According to one aspect of the invention a bistable actuator comprises a magnetic member carried on the operating rod of the spool of a spool and sleeve valve so as to be movably mounted in a housing of magnetic material, permanent magnet means so located in the housing that the movable magnetic member will form part of either one of alternative preferential magnetic flux paths so as to be positively locatable by said magnetic flux in either one of two stable positions and coil means arranged such that predetermined electrical pulse energization thereof, in use, will cause the magnetic flux to be diverted from either one of said paths to the other and so cause movement of the movable magnetic member from either one to the other of said stable positions.

The housing may comprise a tubular member with magnetically closed ends and a longitudinally extending central passage, the permanent magnetic means comprising one or more permanent magnets arranged about said passage within and magnetically coupled to the housing, in a central longitudinal position and magnetised so as to have a generally radial direction of magnetisation, the coil means comprising at least one coil located about said passage to one side of said permanent magnet means and the movable magnetic member being linearly movable within said passage and extending from one end thereof to said permanent magnet means.

The coil means may comprise two coils, one located on each side of said magnet means.

Preferably the tubular member is cylindrical and the permanent magnetic means is in the form of a radially magnetised ring magnet.

The permanent magnet means may be formed of samarium cobalt.

The spool and sleeve valve may comprise the whole bearing for the movable magnetic member.

The foregoing and further features of the invention may be more readily understood from the following description of some preferred embodiments thereof, by way of example, with reference to the accompanying drawings, in which: Figures 1A and 1B are diagrammatic representations of a bistable actuator in its respctive stable stages; Figures 2A and 2B are diagrammatic representations of an alternative bistable actuator in its respective stable states, and Figure 3 is a side elevational view, part in section, of a practical bistable actuator of the type shown in Figures 2A and 2B.

Referring firstly to Figures 1A and 1B there is shown a bistable actuator comprising a cylindrical magnetic housing 10 with magnetically closed ends 11. A radially magnetised permanent ring magnet 12 is located centrally, in the longitudinal direction. within the passage 13 of housing 10. A coil 14 is located in passage 13 to one side of ring magnet 12.

A member 15 of magnetic material is mounted on members 16 of non-magnetic material which in turn are carried by linear bearings 17 on respective ends 11 of housing 10. The member 15 is located within magnet 12 and coil 14 and extends from one end of passage 13 to the magnet 12.

In operation, with the actuator in the stable position shown in Figure 1A the member 15 is positively located by ring magnet 12 with the preferred magnetic flux path shown by lines A in Figure 1A. When it is required to move member 15 to the left to the position shown in FIGURE IB the coil 14 is electrically energised to set up a magnetic flux in path A which opposes the flux of magnet 12. When the flux due to the coil 14 equals the flux due to magnet 12, the flux due to magnet 12 is diverted to path B shown in Figure 1B and member 15 moves to its other stable position. It is merely necessary to pulse coil 14 since member 15 is located in its other position by the magnet flux of path B. The member 15 can be returned to its initial position by pulsing coil 14 with a reverse polarity electric pulse to set up a flux as shown in path A and again the flux of magnet 12 is diverted.

Referring now to Figures 2A and 2B there is shown an alternative embodiment of actuator in which a further coil 14a is located within passage 13 to the other side of magnet 12. A single mounting member 16 is provided with no bearing therefor as will be more fully described hereinafter.

This embodiment has the advantage that it is not necessary to provide electrical switching circuitry for reversing the current flow through the coils 14 and 14a.

There are two possible modes of operation of this embodiment. In the first mode the member 15 can be moved from the position of Figure 2A to 2B by pulsing coil 14 to oppose the flux in path A and conversely the member 15 can be moved from the position of Figure 2B to 2A by pulsing coil 14a to oppose the flux in path B.

In the other mode of operation coil 14a is oppositely pulsed electrically to move member 15 from its Figure 2B to 2A position.

Again member 15 is positively located in one or other of its positions by the flux of magnet 12.

Referring now to Figure 3 there is shown a practical example of the embodiment of actuator shown in Figures 2A and 2B. The actuator is housed in an end cap housing member 18 of a housing assembly 19 for a spool and sleeve valve of the type disclosed in copending United Kingdom patent application No. 46525/73 (Serial No.1433795).

In this embodiment the member 16, which carries the member 15. forms part of the spool 20 of the spool and sleeve valve and no additional bearing is required in end members 11, a buffer member 21 being provided in one member 11 for the spool 20.

The ring magnet 12 is formed of samarium cobalt and is magnetically coupled to the housing member 10 by a ring member 22 of magnetic material e.g. mild steel. In a prototype which has been made and tested.

members 10, 11, 15 and 22 were made of mild steel and each of the coil 14 and 14a comprised 640 turns of 28 Standard Wire Gauge wire. This device operated successfully with the coils 14 and 14a being pulsed with a 24 volts supply, the operaton being as lescribed above.

The Figure 1 embodiment is utilized for the arrangement as shown in Figure 3, omitting one of members 16 and bearings 17.

The actuators of all embodiments have the advantages of providing two stable states without the need for a continuous current drain on the coils and since they operate with pulse actuation the problem of burnt out coils, due to faulty operation, is obviated.

All embodiments are intended to be operated by pulsed direct current but in adition may be operated by rectified alternating current. Further the respective coils could be arranged to be operated by respective half cycles of alternating current, suitably rectified, to give a vibratory operation.

WHAT WE CLAIM IS: 1. A bistable actuator comprising a magnetic member carried on the operating rod of the spool of a spool and sleeve valve so as to be movably mounted in a housing of magnetic material, permanent magnet means so located in the housing that the movable magnetic member will form part of either one of alternative preferential magnetic flux paths so as to be positively locatable by said magnetic flux in either one of two stable positions and coil means arranged such that predetermined electrical pulse energisation thereof, in use, will cause the magnetic flux to be diverted from either one of said paths to the other and so cause movement of the movable magnetic member from either one to the other of said stable positions.

2. A bistable actuator as claimed in claim 1 wherein the housing comprises a tubular member with magnetically closed ends and a longitudinally extending central passage, the permanent magnetic means comprising one or more permanent magnets arranged about said passage. within and magnetically coupled to the housing, in a central longitudinal position and magnetised so as to have a generally radial direction of magnetisation, the coil means comprising at least one coil located about said passage to one side of said permanent magnet means and the movable magnetic member being linearly movable within said passage and extending from one end thereof to said permanent magnet means.

3. A bistable actuator as claimed in claim 2 wherein the coil means comprises two coils, one located on each side of said magnet means.

4. A bistable actuator as claimed in

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. stable position shown in Figure 1A the member 15 is positively located by ring magnet 12 with the preferred magnetic flux path shown by lines A in Figure 1A. When it is required to move member 15 to the left to the position shown in FIGURE IB the coil 14 is electrically energised to set up a magnetic flux in path A which opposes the flux of magnet 12. When the flux due to the coil 14 equals the flux due to magnet 12, the flux due to magnet 12 is diverted to path B shown in Figure 1B and member 15 moves to its other stable position. It is merely necessary to pulse coil 14 since member 15 is located in its other position by the magnet flux of path B.The member 15 can be returned to its initial position by pulsing coil 14 with a reverse polarity electric pulse to set up a flux as shown in path A and again the flux of magnet 12 is diverted. Referring now to Figures 2A and 2B there is shown an alternative embodiment of actuator in which a further coil 14a is located within passage 13 to the other side of magnet 12. A single mounting member 16 is provided with no bearing therefor as will be more fully described hereinafter. This embodiment has the advantage that it is not necessary to provide electrical switching circuitry for reversing the current flow through the coils 14 and 14a. There are two possible modes of operation of this embodiment. In the first mode the member 15 can be moved from the position of Figure 2A to 2B by pulsing coil 14 to oppose the flux in path A and conversely the member 15 can be moved from the position of Figure 2B to 2A by pulsing coil 14a to oppose the flux in path B. In the other mode of operation coil 14a is oppositely pulsed electrically to move member 15 from its Figure 2B to 2A position. Again member 15 is positively located in one or other of its positions by the flux of magnet 12. Referring now to Figure 3 there is shown a practical example of the embodiment of actuator shown in Figures 2A and 2B. The actuator is housed in an end cap housing member 18 of a housing assembly 19 for a spool and sleeve valve of the type disclosed in copending United Kingdom patent application No. 46525/73 (Serial No.1433795). In this embodiment the member 16, which carries the member 15. forms part of the spool 20 of the spool and sleeve valve and no additional bearing is required in end members 11, a buffer member 21 being provided in one member 11 for the spool 20. The ring magnet 12 is formed of samarium cobalt and is magnetically coupled to the housing member 10 by a ring member 22 of magnetic material e.g. mild steel. In a prototype which has been made and tested. members 10, 11, 15 and 22 were made of mild steel and each of the coil 14 and 14a comprised 640 turns of 28 Standard Wire Gauge wire. This device operated successfully with the coils 14 and 14a being pulsed with a 24 volts supply, the operaton being as lescribed above. The Figure 1 embodiment is utilized for the arrangement as shown in Figure 3, omitting one of members 16 and bearings 17. The actuators of all embodiments have the advantages of providing two stable states without the need for a continuous current drain on the coils and since they operate with pulse actuation the problem of burnt out coils, due to faulty operation, is obviated. All embodiments are intended to be operated by pulsed direct current but in adition may be operated by rectified alternating current. Further the respective coils could be arranged to be operated by respective half cycles of alternating current, suitably rectified, to give a vibratory operation. WHAT WE CLAIM IS:

1. A bistable actuator comprising a magnetic member carried on the operating rod of the spool of a spool and sleeve valve so as to be movably mounted in a housing of magnetic material, permanent magnet means so located in the housing that the movable magnetic member will form part of either one of alternative preferential magnetic flux paths so as to be positively locatable by said magnetic flux in either one of two stable positions and coil means arranged such that predetermined electrical pulse energisation thereof, in use, will cause the magnetic flux to be diverted from either one of said paths to the other and so cause movement of the movable magnetic member from either one to the other of said stable positions.

4. A bistable actuator as claimed in

claim 2 or 3 wherein the tubular member is cylindrical and the permanent magnet means is in the form of a radially magnetised ring magnet.

5. A bistable actuator as claimed in any preceding claim wherein said spool comprises the sole bearing for the movable magnetic member.

6. A bistable actuator as claimed in any preceding claim wherein the permanent magnet means is formed of samarium cobalt.

7. A bistable actuator substantially as hereinbefore described with reference to the accompanying drawings.