GB2062356A - Multi-position electromagnetic actuator - Google Patents
Multi-position electromagnetic actuator Download PDFInfo
- Publication number
- GB2062356A GB2062356A GB7937495A GB7937495A GB2062356A GB 2062356 A GB2062356 A GB 2062356A GB 7937495 A GB7937495 A GB 7937495A GB 7937495 A GB7937495 A GB 7937495A GB 2062356 A GB2062356 A GB 2062356A
- Authority
- GB
- United Kingdom
- Prior art keywords
- actuator
- electromagnet
- members
- electromagnets
- relative
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/06—Electromagnets; Actuators including electromagnets
- H01F7/08—Electromagnets; Actuators including electromagnets with armatures
- H01F7/14—Pivoting armatures
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Reciprocating, Oscillating Or Vibrating Motors (AREA)
Abstract
A rotary actuator has two relatively movable members 2, 20 and means 6, 6a, 6b, 28 for selectively positioning the members in a plurality of relative positions B, C, D. The selective positioning means comprise electromagnets 6, 6a, 6b individually energisable to produce a plurality of individual magnetic fields and magnetic elements 28 responsive to each individual magnetic field to rotate a rotor 20 into a respective one of the relative positions. When one electromagnet 6a and element 28 are in register the other magnets and elements are out of register by 15 DEG . In another arrangement, the rotor is replaced by a pivoted arm incorporating a permanent magnet. <IMAGE>
Description
SPECIFICATION
Electromagnetic actuator
This invention relates to electromagnetic actuators for selectively positioning an output member in a plurality of different positions.
Such actuators for positioning an output member in either of two positions are well known and in one type which is employed, in which the output member is a rotary shaft, the shaft is rotated from one position to another by electromagnetic force and when desired is returned to the other position by a biasing spring upon release of the electromagnetic force.
However, if three or more positions for the output member are required, the principle of using electromagnetic force to displace the output member in one direction and mechanical biasing force to return it in the other direction can no longer be applied.
The present invention is primarily but not exclusively directed to electromagnetic actuators capable of positioning an output member in three or possibly more different positions.
Two different embodiments of the invention will be described, which involved positioning two members selectively in different positions relative to each other, and in both an intermediate position is defined by a localised magnetic field generated by means on one of the members attracting into registration with itself a magnetic element carried on the other of the members. In both embodiments, the different relative positions are angular positions about an axis, but it should be appreciated that the principles involved may be applied to linear actuators or actuators causing relative movement along a differently shaped path.
From one aspect, a multi-position electromagnetic actuator in accordance with the invention comprises two members, one of them being provided with a plurality of electromagnets defining when energised respective magnetic fields which are spaced apart in a particular direction, and on the other member a plurality of magnetic elements spaced apart in the same direction but with different spacings from the fields, such that different elements come into register with a said magnetic field at different relative positions of the members, the electromagnets being selectively energisable to cause changes of the said relative positions by the field of an electromagnet when energised bringing an adjacent element into registration with it.
In an embodiment which will be described below, the actuator is a rotary one and the direction in which the electromagnets and magnetic elements are spaced apart is a tangential direction around an axis.
From another aspect, there is provided a multiposition electromagnetic actuator comprising two members, one member carrying a first electromagnet which when energised defines a localised field and a second electromagnet which is selectively energisable to produce a field in either of two opposed directions, the other member carrying a magnetic element cooperating with the first electromagnet and effective to position said other element centrally when the first electromagnet is energised and a permanent magnet co-operating with the second electromagnet and effective to position said other element to one side or the other of the central position depending upon the direction of energisation of the second electromagnet.
In the particular embodiment which employs this principle, the effectiveness of the second electromagnet is enhanced by providing a third electromagnet which co-operates with it to define between them the selectively directional field.
In order that the invention may be more clearly understood two embodiments thereof will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which:
Figure 1 is a cross-sectional view through one embodiment of the invention;
Figure 2 is a plan view from above the Figure 1 embodiment, with its top and its rotor removed;
Figure 3 is a view from above of the rotor;
Figure 4 shows a wiring diagram for the embodiment of Figures 1 to 3;
Figure 5 is a view from above of a further embodiment, with the top of its casing removed;
Figure 6 is a partial cross-sectional view of the embodiment of Figure 5, looking in the direction of the arrow A in Figure 5; and
Figure 7 is a wiring diagram for the embodiment of Figures 5 and 6.
Referring to Figures 1 to 3, the actuator comprises a casing having a cylindrical body 2 and a top 4 suitably secured thereon, the casing being made of non-magnetic material and preferably metal such as aluminium so as to serve as a heat sink to help dissipate heat generated during the operation of the actuator.
Located within the casing are three identical electromagnets 6, 6a and 6b equally spaced at angles of 1200 around the central axis. One of the electromagnets will be described in detail with reference to Figure 1. It comprises a U-shaped yoke 8 of soft iron to one of whose arms a soft iron cylindrical core 10 is secured in any suitable manner. An annular coil 1 2 is fitted over the core 10 to complete the electromagnet and define a field gap between the top arm 14 of the yoke 8 and the top end 16 of the core 10. The electromagnet is secured within the casing by means of a screw 1 8 of non-magnet material passing up through the base of the casing 2 and being screwed into a bore formed through the lower arm of yoke 8 and into the centre of the core 10.In Figure 2, references referring to components of electromagnets 6a and 6b have been given the suffixes a and b respectively.
Also within the -casing 2 there is a rotor 20 of non-magnetic material such as aluminium or plastics which is fixedly secured to a central output shaft 22 whose lower end is supported in a plain bearing 24 recessed into the base of the casing and which also passes through a bearing aperture 26 in the top 4 of the casing. Three magnetic elements of soft iron 28, 28a and 28b, are fitted into apertures in the rotor 20 and the angular spacing between magnetic elements 28 and 28a, and between magnetic elements 28 and 28b is in each case 1050.
Consequently, referring to Figures 2 and 3, if it is assumed that the rotor is in an angular position such that element 28a lies exactly in register with electromagnet 6a i.e. at angular position B, then element 28 will lie at angular position C displaced 150 from the centre of electromagnet 6 and element 28b will lie at angular position D displaced 300 from the centre of electromagnet 6b. Figure 4 shows how the three coils 1 2a, 1 2b and 1 2c are wired in parallel with each other and selectively operable by means of a three-position switch 30, from a battery 32. Of course, any suitable power source might be used. Placing the switch 30 in its uppermost position would energise coil 1 2a and this would hold the rotor 20 in the angular position just described.
It will be appreciated from Figure 2 that magnetic element 28 at angular position C lies about half-way into the magnetic gap of electromagnet 6 and magnetic element 28b lies very close to the magnetic gap of electromagnet Sb. In both cases, their potential electromagnetic linkage with the electromagnets 6 and 6b is sufficient that, if switch 30 is shifted either to energise coil 1 2b or coil 1 2c, then respectively magnetic element 28 will be attracted into register with electromagnet 6 thus shifting the whole rotor anticlockwise through 1 50 so that elements 28 and 28b reach angular positions E and F or magnetic element 28b is attracted into register with electromagnet 6b thus becoming
positioned at angular position G, thus shifting the whole rotor through 300.Consequently, the rotor can be rapidly re-positioned into any one of three angular positions displaced from each other by 1 50 by selectively positioning the switch 30.
To enable the output shaft 22 to remain in
position when all the electromagnets are de
energised, a detent mechanism may be provided
such as that illustrated in Figure 3 where three
recesses 34 are provided in the rim of the rotor 20
and a detent ball 36 is spring loaded towards the disc rim by means of a compression spring 38
located in a bore 40. The recesses 34 are
angularly spaced 1 50 apart so that the shaft will
be retained in any one of the three positions to
which it can be set by means of the
electromagnets. The strength of the detent will
not be such that the rotor cannot be shifted
between angular positions by the electromagnets,
of course.
Alternatively. an electromagnetically operated
detent may be arranged which is normally biased
into a position where it interlocks with a formation
on disc 20 to positively fix the position of the disc,
in each of its three possible positions, but which is
withdrawn from engagement with the disc upon energisation of any of the electromagneRs. In this way, the disc is left completely free to rotate as soon as any electromagnet is energised in order to rotate it, but once the electromagnets are deenergised then the detent engages and holds the disc in its last position.
The concept embodied in the actuator just described can of course be used to provide more than three output positions by increasing the number of electromagnets and magnetic elements and the increments between the positions need not be equal since they can be varied by varying the positions of the magnetic elements relative to the positions of the electromagnets. Also, of course, the magnetic elements could be given equal spacings and the spacings of the electromagnets made unequal, or both the magnetic elements and the electromagnets may be unequally spaced.
Compared with existing two-position actuators and even with the three-position actuator which will be described below, the actuator which has just been described offers the possibility of very quiet switching between its different positions because the positions are not defined by means of a positive stop or abutment limiting the movement of the output member at either end of its travel.
Referring now to Figures 5 and 6, the threeposition actuator shown therein comprises a casing having a body 42 and a top 44.
A first electromagnet 46 secured within the body portion 42 comprises an L-shaped soft iron element 48 having an aperture in its horizontal arm into which an annular soft iron core 50 is press-fitted. A coil 52 is mounted on the core 50 and a further soft iron plate 54 having an aperture therein is press-fitted over the top end of the core 50, thus forming a magnetic gap between the right-hand end of the plate 54 and the top end of the vertical arm of plate 48.
The central bore in the core 50 serves as a bearing for an output shaft 56 to which is fixedly secured an arm 58 of non-magnetic material which has fitted into a recess at one end thereof an element 60 of soft iron or other magnetic material located in the gap of the first electromagnet 46 and which has fitted into a recess at the other end thereof a disc-shaped permanent magnet 62 which has a north pole on one face and a south pole on the opposite face.
Also within the casing are mounted second and third electromagnets 64 and 66 having coils 68 and 70 and cores 72 and 74, respectively. The coils 68 and 70 are wound in opposite directions and are connected in series as shown in Figure 9 so that each of them produces a magnetic field which can be reversed in direction by operating a ganged switch 76 which connects them between a power source and ground.The fields produced by coils 68 and 70 are always in opposite directions to each other so that one repels and one attracts the permanent magnet 62, owing to its polarised nature, and hence the two fields assist each other either in driving the lever 58 fully anticlockwise as shown in Figure 5 when the switch 76 is positioned to energise to coils in one direction, or to drive it fully clockwise when switch
76 is shifted so as to energise coils 68 and 70 in the opposite direction.
If coils 68 and 70 are both de-energised, then energisation of coil 52 develops an electromagnetic field in the gap between plates 54 and 48, which field is iinked with magnetic element 60 and hence attracts it and brings it into register centrally within that gap, thus providing a central position for the shaft 56.
It will therefore be appreciated that by suitably energising and de-energising the three coils, the device enables the output shaft to be selectively positioned in any of three angular positions.
It should be appreciated that the circuitry shown in Figures 4 and 7 is intended purely to illustrate the manner in which the actuator operates and in any practical situation different and more sophisticated switching arrangements would be employed to enable high-speed selective positioning of the actuator.
One application of actuators such as have been described is to selectively position a guide vane which directs pieces of paper being delivered along a common input path into selective ones of three possible output paths, in a sorting machine.
Claims (24)
1. An actuator having two relative movable members and means for selectively positioning the members in a plurality of relative positions, the selective positioning means comprising means for generating a plurality of individual magnetic fields and means responsive to each individual magnetic field to urge the two members into a respective one of the relative positions, and the selective positioning means being arranged such that changes from each relative position to another are caused by applying a selected one of the individual magnetic fields to the means responsive thereto.
2. An actuator means as claimed in claim 1, in which the selective positioning means comprise
means on one of the members arranged to provide a localised magnetic field which attracts into
registration with itself a magnetic or magnetisable element on the other of the members to define at least one of the relative positions.
3. An actuator as claimed in claim 2, in which the selective positioning means further comprise
means on one of the members arranged to provide
localised magnetic fields which attract into registration with themselves magnetic or magnetisabie elements on the other of the
members to define the other relative position(s).
4. An actuator as claimed in claim 2, in which the selective positioning means further comprise means on one of the members arranged to provide individual fields in a single location and each in a respective one of two opposed directions which co-operate with a magnet on the other of the members to define the other relative position(s).
5. An actuator as claimed in any preceding claim, in which the two members are relatively
rotatable and in which the plurality of relative positions are relative angular positions about a common axis.
6. An actuator as claimed in claim 1, in which the selective positioning means comprise a plurality of electromagnets on one of the members which are spaced apart to define when energised respective localised magnetic fields, and a plurality of magnetisable elements on the other of the members which are also spaced apart but with different spacings from the electromagnets, such that different elements come into register with a respective one of the magnetic fields at different relative positions of the members, the electromagnets being selectively energisable to cause changes of the relative positions by the field of the particular electromagnet which is energised bringing an adjacent element into registration with it.
7. An actuator as claimed in claim 6, in which the two members are relatively rotatable about a common axis and in which the electromagnets are angularly spaced relative to one another about the axis and the magnetisable elements are also angularly spaced relative to one another about the axis.
8. An actuator as claimed in claim 7, in which either the electromagnet or the magnetisable elements are equiangularly spaced about the axis.
9. An actuator as claimed in claim 7 or 8, in which the angular spacing between the electromagnets is different for each pair of adjacent electromagnets.
10. An actuator as claimed in claim 7 or 8, in which the angular spacing between the electromagnets is the same for some but not all of the pairs of adjacent electromagnets.
11. An actuator as claimed in claim 7 or 8, in which the angular spacing between the magnetisable elements is different for each pair of adjacent magnetisable elements.
12. An actuator as claimed in claim 7 or 8, in which the angular spacing between the magnetisable elements is the same for some but not all of the pairs of adjacent magnetisable elements.
13. An actuator as claimed in claim 10 or 12, in which there are three of the electromagnets and three of the magnetisable elements, and in which the angular spacing for those pairs which have the same angular spacing is approximately 1050.
14. An actuator as claimed in any of claims 6 to 13, in which location means are provided for engaging one of the members in each of the relative positions so as positively to locate that member in the selected relative position.
1 5. An actuator as claimed in claim 14, in which said one member has a plurality of recesses for receiving the location means, which recesses are displacled relative to one another by an amount which corresponds to the difference in spacings between a respective pair of electromagnets and an associated respective pair of magnetisable elements.
1 6. An actuator as claimed in any of claims 6 to 15, in which each electromagnet is arranged to be spaced from the adjacent element when that element is in register with the field of the electromagnet.
17. An actuator as claimed in claim 1, in which the selective positioning means comprise a first electromagnet which when energised defines a localised field and a second electromagnet which is selectively energisable to produce a field in either of two of opposed directions, said first and second electromagnets being carried on one of the members, a magnetisable element on the other of the members co-operating with the first electromagnet and effective to position said other
member in an intermediate position when the first electromagnet is energised, and a permanent
magnet on said other member co-operating with the second electromagnet and effective to
position said other member to one side or the
other of the intermediate position depending upon
the direction of energisation of the second
electromagnet.
18. An actuator as claimed in claim 17, in
which the selective positioning means further
comprise a third electromagnet on said one
member which co-operates with the second
electromagnet to define between them the
selectively directional fields.
19. An actuator as claimed in claim 17 or 18, in
which the two members are rotatable relative to
one another about a common axis.
20. An actuator as claimed in claim 19, in
which said other member comprises a plate
carrying at diametrically opposed regions relative
to the common axis the magnetisable element and
the permanent magnet.
21. An electromagnetic actuator substantially as herein particularly described with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.
22. An electromagnetic actuator substantially as herein particularly described with reference to and as illustrated in Figures 5 to 7 of the accompanying drawings.
23. A multi-position electromagnetic actuator comprising two members, one of them being provided with a plurality of electromagnets defining when energised respective magnetic fields which are spaced apart in a particular direction, and on the other member a plurality of magnetic elements spaced apart in the same direction but with different spacings from the fields, such that different elements come into register with a said magnetic field at different relative positions of the members, the electromagnets being selective energisable to cause changes of the said relative positions by the field of an electromagnet when energised bringing an adjacent element into registration with it.
24. A multi-positioned electromagnetic actuator comprising two members, one member carrying a first electromagnet which when anergised defines a localised field and a second electromagnet which is selectively energisable to produce a field in either of two opposed directions, the other member carrying a magnetic element cooperating with the first electromagnet and effective to position said other member centrally when the first electromagnet is energised and a permanent magnet cooperating with the second electromagnet and effective to position said other member to one side or the other of the central position depending upon the direction of energisation of the second electromagnet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7937495A GB2062356A (en) | 1979-10-30 | 1979-10-30 | Multi-position electromagnetic actuator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7937495A GB2062356A (en) | 1979-10-30 | 1979-10-30 | Multi-position electromagnetic actuator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2062356A true GB2062356A (en) | 1981-05-20 |
Family
ID=10508850
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7937495A Withdrawn GB2062356A (en) | 1979-10-30 | 1979-10-30 | Multi-position electromagnetic actuator |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2062356A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3736695A1 (en) * | 1986-10-31 | 1988-05-11 | Atsugi Motor Parts Co Ltd | TURNING ACTUATOR |
| EP0329471A2 (en) * | 1988-02-17 | 1989-08-23 | Unisia Jecs Corporation | Rotary actuator for variable damping force shock absorber |
| US5214337A (en) * | 1990-07-19 | 1993-05-25 | Atsugi Unisia Corp. | Electromagnetic rotary actuator |
| EP0836202A2 (en) * | 1996-10-12 | 1998-04-15 | Lucas Industries Inc. | Rotary solenoid |
-
1979
- 1979-10-30 GB GB7937495A patent/GB2062356A/en not_active Withdrawn
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3736695A1 (en) * | 1986-10-31 | 1988-05-11 | Atsugi Motor Parts Co Ltd | TURNING ACTUATOR |
| EP0329471A2 (en) * | 1988-02-17 | 1989-08-23 | Unisia Jecs Corporation | Rotary actuator for variable damping force shock absorber |
| EP0329471A3 (en) * | 1988-02-17 | 1990-05-23 | Atsugi Motor Parts Co. Ltd. | Rotary actuator for variable damping force shock absorber |
| US5148895A (en) * | 1988-02-17 | 1992-09-22 | Atsugi Motor Parts Company, Limited | Rotary actuator for variable damping force shock absorber |
| US5214337A (en) * | 1990-07-19 | 1993-05-25 | Atsugi Unisia Corp. | Electromagnetic rotary actuator |
| EP0836202A2 (en) * | 1996-10-12 | 1998-04-15 | Lucas Industries Inc. | Rotary solenoid |
| EP0836202A3 (en) * | 1996-10-12 | 1998-08-05 | Lucas Industries Inc. | Rotary solenoid |
| US6078236A (en) * | 1996-10-12 | 2000-06-20 | Lucas Industries Plc | Rotary solenoid |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |