GB1594578A

GB1594578A - Electromagnetic actuator circuits

Info

Publication number: GB1594578A
Application number: GB4980076A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-10-21
Filing date: 1977-10-21
Publication date: 1981-07-30

Description

(54) IMPROVEMENTS IN AND RELATING TO ELECTROMAGNETIC ACTUATOR CIRCUITS (71) I, JOHN CHARLES HUMPHREYS HART, a British subject, of "Dalriada", Taynuilt, Argyll, PA35 1JE (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 actuator circuits, to circuits suitable for actuating bistable electromagnetic actuators incorporating latching, such as permanent magnet latching.

According to the invention there is provided an actuating circuit for alternate energisation u of two coils of a bistable electro magnetic actuator device wherein two Hall Effect switch devices, connected one in such energisation circuit for the coils, are so located with respect to permanent magnet means moveable with or located adjacent so as to be effected by movement of an armature of the electromagnetic device, that when eithercoil is energised to move the armature from one to its other position such movement of the armature causes the respective Hall Effect switch device to disconnect the energisation circuit for that coil.

The permanent magnet means may be located to move with the armature and the Hall Effect switch devices may be located such that the permanent magnet means is adjacent one such switch device in one position thereof and is adjacent the other such switch device in the other position thereof.

Alternatively the permanent magnet means may provide the driving force for movement of the armature, being located centrally between the two coils, and the Hall Effect switch devices are located one adjacent each of the two end positions of travel of the armature.

The actuating circuit may include timing means arranged to disconnect the energisation circuit for the coils should the Hall Effect switch devices not disconnect such circuit within a predetermined time from connection of such energisation circuit.

The actuating circuit may also include zener diodes connected so as to cut off the current flow to the coils upon disconnection of the energisation circuit.

The foregoing and further features of the invention may be more readily understood from the following description of two preferred embodiments thereof, by way of example, with reference to the accompanying drawing in which there is shown a schematic representation of an actuator with alternative arrangements of Hall Effect switches for controlling the energisation circuit thereof.

Referring now to the drawing there is shown an actuator which comprises a cylindrical housing 10 of magnetisable material containing an armature 11 slidably mounted between end stops 12a and 12b of magnetisable material. A radially magnetised magnet means 13 is centrally located between coils 14 and 15. The armature 11 is maintained in the position shown by a magnetic field of magnet 13 flowing from magnet 13 around housing 10, end stop 12a and armature 11. To move armature 11 to the right coil 14 is energised to oppose the magnetic flux and a new flux path including end stop 12b is closed and maintains armature 11 to the right as shown in the drawing.

The armature 11 is mounted on a shaft 16 and in one embodiment of the invention the shaft 16 carries or is formed with a permanent magnet 17 which is located adjacent a Hall Effect switch 18 when armature 11 is in the left position and is located adjacent Hall Effect switch 19 when armature 11 is in the right position as shown in the drawing. The switch 19 which is normally closed is connected to be in the energisation circuit for coil 14 so that when such coil is energised and armature 11 moves to the right the proximity of permanent magnet 17 to switch 19 causes such switch 19 to open and disconnect the energisation circuit for coil 14. Similarly the switch 18 is connected in the energisation circuit for coil 15.The arrangement of switches 18 and 19 and the permanent magnet 17 can be utilised with any form of bistable electromagnet actuator with latching at each stable position whether or not such latching is magnetic.

In a further embodiment of the invention respective Hall Effect switches 20 and 21 can be located in end stops 12a and 12b. In this arrangement switch 21 is connected with coil 14 and switch 20 with coil 15. Coil 14 is energised to move armature 11 to the right and when such armature has reached a predetermined position towards the right, which position can be adjusted by controlling the flux magnitude which actuates switch 21, the switch 21 is actuated to open the energisation circuit for coil 14.

Similarly switch 20 acts on the energisation circuit for coil 15 when armature 11 is to be moved to the right.

In both of the embodiments illustrated the Hall Effect switches may be devices commercially available as MICRO SWITCH (Registered Trade Mark) devices type SS from Honeywell Corporation of Freeport, Illinois 61032, United States of America.

Also in both embodiments timers may be included in the coil energisation circuits so that such circuits are disconnected after a predetermined time so as to prevent the coils burning out if the armature becomes stuck in one position and hence the respective Hall Effect switch is not opened.

Also zener diodes may be included in the circuits to reduce residual current flow in the coils after disconnection of the coils, so minimising coil temperature rise.

WHAT I CLAIM IS: 1. An actuating circuit for alternate energisation of two coils of a bistable electro magnetic actuator device wherein two Hall Effect switch devices, connected one in such energisation circuit for the coils, are so located with respect to permanent magnet means moveable with or located adjacent so as to be effected by movement of an armature of the electromagnetic device, that when either coil is energised to move the armature from one to its other position such movement of the armature causes the respective Hall Effect switch device to disconnect the energisation circuit for that coil.

2. An actuating circuit as claimed in claim 1 wherein the permanent magnet means is located to move with the armature and the Hall Effect switch devices are located so that the permanent magnet means is adjacent one such switch device in one position thereof and is adjacent the other such switch device in the other position thereof.

3. An actuating circuit as claimed in claim 1 wherein the permanent magnet means provides the driving force for movement of the armature, being located centrally between the two coils, and the Hall Effect switch devices are located one adjacent each of the two end positions of travel of the armature.

4. An actuating circuit as claimed in any preceding claim wherein timing means is arranged to disconnect the energisation circuit for the coils should the Hall Effect switch devices not disconnect such circuit within a predetermined time from connection of such energisation circuit.

5. An actuating circuit as claimed in any preceding claim including zener diodes connected so as to reduce residual current flow in the coils upon disconnection of the energisation circuit.

6. An actuating circuit for an electromagnetic actuator substantially as hereinbefore described with reference to the accompanying drawing.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. switches 18 and 19 and the permanent magnet 17 can be utilised with any form of bistable electromagnet actuator with latching at each stable position whether or not such latching is magnetic. In a further embodiment of the invention respective Hall Effect switches 20 and 21 can be located in end stops 12a and 12b. In this arrangement switch 21 is connected with coil 14 and switch 20 with coil 15. Coil 14 is energised to move armature 11 to the right and when such armature has reached a predetermined position towards the right, which position can be adjusted by controlling the flux magnitude which actuates switch 21, the switch 21 is actuated to open the energisation circuit for coil 14. Similarly switch 20 acts on the energisation circuit for coil 15 when armature 11 is to be moved to the right. In both of the embodiments illustrated the Hall Effect switches may be devices commercially available as MICRO SWITCH (Registered Trade Mark) devices type SS from Honeywell Corporation of Freeport, Illinois 61032, United States of America. Also in both embodiments timers may be included in the coil energisation circuits so that such circuits are disconnected after a predetermined time so as to prevent the coils burning out if the armature becomes stuck in one position and hence the respective Hall Effect switch is not opened. Also zener diodes may be included in the circuits to reduce residual current flow in the coils after disconnection of the coils, so minimising coil temperature rise. WHAT I CLAIM IS:

1. An actuating circuit for alternate energisation of two coils of a bistable electro magnetic actuator device wherein two Hall Effect switch devices, connected one in such energisation circuit for the coils, are so located with respect to permanent magnet means moveable with or located adjacent so as to be effected by movement of an armature of the electromagnetic device, that when either coil is energised to move the armature from one to its other position such movement of the armature causes the respective Hall Effect switch device to disconnect the energisation circuit for that coil.