Polarized Electromagnetic Relays Having A Floating Armature

Abstract

A polarized electromagnetic relay wherein an armature is freely movable about its center of gravity between two pairs of contact members.

Description

The present invention relates to polarized magnetic relays of the kinds described and claimed in my U.S. Pat. No. 3,514,728 issued May 26, 1970, according to which the armature is movable either in a straight line or in rotary fashion about one of its ends. It is an object of the invention to provide improvements in such relays employing a rotary movement of the armature.

More particularly it is an object of the invention to provide means acting on the movable armature to cause the latter to rotate about its center of gravity, but in such a manner that no physical center of gravity, for example, a pivot, strip or the like, is necessary, the movement thus imparted to the armature being effected very sharply under the effect of an electrical control pulse.

It is a well-known fact that this type of movement requires a minimum energy for an armature of given weight. The consequent advantages obtained relate, as is well known, to the magnetic energy required, the energy of impact on arrival and the speed obtained. Moreover, this kind of movement makes simpler the provision of stop members which prevent the armature from taking up certain positions. These stop members may be either on the fixed portion or on the moving armature.

The material of which the stop members is made may either be hard so as to define the limits of the permitted path of travel, or elastic so as to define the mean position of the armature without any actual interference with the movement itself or constituting any kind of retaining member.

The latter case is thus a mean between the free, i.e., unbiased, armature devices and the more conventional arrangements in which the movement of the armature is determined by mechanical members such as pivots and the like, a design which would justify the description "semifree armature" in order to distinguish them from the free armatures described above.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings which schematically show some embodiments thereof by way of example, and in which:

FIG. 1 shows a first embodiment employing a free (unbiased) armature,

FIG. 2 shows a second embodiment with a magnetic strip around the armature,

FIG. 3 shows another embodiment utilizing one or more permanent magnets,

FIGS. 4 and 5 show an embodiment using iron electromagnets,

FIG. 6 shows an embodiment employing electromagnetic coils,

FIG. 7 shows a modification of the arrangement of FIG. 6, where the energizing coils are dispersed with,

FIG. 8 shows a practical disposition using a plurality of armatures,

FIGS. 9 and 10 show the two arrangements where two relays are used in tandem, and

FIGS. 11 and 12 show arrangements to moving a free armature about its center of gravity.

Referring now to the drawings, in FIG. 1, the reference numerals 1, 2, 3 and 4 relate to the magnetic poles of a relay while the numerals 5, 6, 7 and 8 refer to a contactor plate made, for example, from silver or rhodium, which also constitute the residual airgap when the armature is pulled into the polepiece. The free or unbiased armature is shown at 9 and is made of magnetically soft or hard material and which is only able to take up two stable positions, namely those in which its ends are pulled in by opposite magnetic poles. The reference 10 is a control or energizing coil which may be composed of one or several separate coils with or without intermediate connections, the role of the said coils being to magnetize the armature 9 in either sense.

Passive (optional) stop members 11 and 12 act to prevent the armature from being applied accidentally against the contactor plates located on the same side (5 and 8 or 6 and 7).

Thus, a pulse of suitably polarized current will cause the armature to pivot sharply about its center of gravity in order to apply it in the opposite position.

The armature 9 is covered with a contact metal so as to ensure an electric connection between the fixed contacts to which its lateral ends are applied.

It might appear desirable for an external magnetic strip to provide a return path for the lines of magnetic flux. In practice, it was found that the effectiveness of this strip was associated with the ratios of the dimensions of the components in such a manner that in certain cases it is possible to consider omitting the said strip, particularly when it is intending to miniaturize the relay.

An important embodiment of this device is shown in FIG. 2, the only difference from FIG. 1 residing in the fact that the free armature and contacts are placed in a sealed enclosure in order to enable the switching circuit to be under vacuum, or located in an inert gas atmosphere or in a dielectric liquid.

Although this arrangement might appear similar to arrangements employing encapsulated contacts (ILS) it is basically different in that the movable armature is mechanically free.

Consequently, certain disadvantages inherent in the ILS: considerable dynamic period, bounce, uncertainty of operating values, relatively low resistance to vibrations, etc. are substantially eliminated in free armature arrangements.

It should be noted that the principle of the free armature makes it possible to obtain enclosed or encapsulated contacts which ensure bistable and tristable functions as will be explained in connection with FIG. 5.

It will be apparent that the locating of a free armature and its contacts within a sealed enclosure is not limited to the arrangement shown in FIG. 1 but is applicable to the other arrangements herein described. However, in order to simplify matters, this is not shown in the other Figures.

The magnetic vectors of the magnets shown in FIGS. 1 and 2 are equipolar, but their function consists in placing the free armature or armatures in a so-called "reference" field which may be produced by other conventional means such as:

1. Soft magnetic members magnetized by one or more general magnets as shown in FIG. 3. The arrows shown in heavy lines here indicate either the poles of permanent magnets which enclose the device or ferrites which are magnetized transversely.

2. Soft magnetic members which are magnetized by one or more coils traversed by electric currents as shown in FIG. 4, in which the reference number 13 denotes a control or energizing coil, 14 being a reference coil, the axes of the two coils being mutually perpendicular.

It is also possible to invert the effect of the control pulses or to create a third stable position using additional magnets or coils which are only used when the reference coil is not energized as shown in FIG. 5.

3. The coil or coils themselves, omitting the soft magnetic member as described in 2. above, as shown in FIGS. 6.

The latter arrangements shown in FIGS. 4, 5 and 6, demonstrate the possibility of combining the functions of the control or energizing and the reference coils in various ways.

In fact, since the control coil is traversed by a current in a given direction, it is enough simply to reverse the current and to maintain it in the reference coil in order to cause the movement and holding of the armature.

In this case, it is then the control coil which makes it possible to reverse the effect produced by a current passing through the reference coil. This characteristic may be important when a number of free armatures are grouped together, each with its own control coil within a single reference coil.

Moreover, with the arrangements described above, if one or more armatures of magnetically hard material are used, it is possible either to dispense with the control coil or coils in the arrangement shown in FIGS. 4, 5, 6 (such as the embodiment shown in FIG. 7 which is derived from FIG. 6), or to retain the two coils and to give to the pulses of the control coil or coils a value which is sufficient to overcome the coercive field of the material of the armature which then remains magnetized after current has been suppressed in the control coil or coils.

In the examples shown in FIGS. 4 or 5, the advantages obtained are as follows:

1. the armature remains in the last position it assumed, even if the currents in the two coils cancel one another out.

2. the position of the armature remains a function of two parameters; if we indicate by a + and - signs the two possible positions of the armature and by a + sign the direction of the current in each coil which brings the armature into its + position, we see that the four cases which may occur follow the rule of signs in algebra.

The following modifications are referred to by way of nonlimiting example.

a. the possibility of acting upon a number of armatures using the same control coil, each armature being arranged in its own enclosure comprising contacts which it has to bridge, or the same armatures being, on the contrary, arranged in a common enclosure and being either independent or elastically coupled.

b. the possibility of associating becomes different manners a number of devices having common magnets:

1. by considering that FIG. 1 represents a section through four magnets of a marked elongated shape, between which are located a number of adjacent coils, each of which comprises one or more armatures, as is shown in FIG. 8;

2. by locating horizontally in the plane of FIG. 1, a number of devices in accordance with this Figure. FIG. 9 shows an embodiment with two devices;

3. by repeating vertically in the plane of FIG. 1, the device shown in that Figure; we then obtain the arrangement of which FIG. 10 shows an example.

Mention will be made of two more arrangements, shown in FIGS. 11 and 12, which make it possible to ensure the movement of a free armature about its center of gravity.

According to FIG. 11, the parts 21, 22, 23, 24 may be made of a magnetically soft material while the parts 25 and 26 are of magnetically hard material. Obviously the reverse may also be the case, i.e., the parts 21, 22, 23, 24 may be of magnetically hard material while parts 25 and 26 are of magnetically soft material.

In FIG. 12, the reference numerals 31 to 38 designate magnets, while 39-42 are parts made from magnetically soft material. As has been stated in connection with FIG. 11, the combination of the magnets and parts made from a magnetically soft material may be varied.

In the examples cited during the above description, it has been implicitly assumed that the magnets are of substantially equal strength. It will be apparent that, without departing from the scope of the invention, it is possible to use magnets of different strengths or even to omit some of them.

According to these modifications, it becomes possible to provide devices either of a dissymmetrical bistable type (more sensitive in one direction than in the other) or monostable (one working position, one rest position).

Claims

I claim:

1. In a polarized electromagnetic relay having switching means including a floating armature which is movable about its center of gravity and which is made of an electrically conductive magnetic metal, permanent magnetic field producing means for producing a reference field for holding the armature in a stable position, four contact elements of nonmagnetic electrically conductive metal arranged to provide two diagonally positioned pairs of contacts which contact the opposite ends of the armature, act as end of travel stops and provide residual airgaps in each of two switching positions of the armature, and electromagnetic field producing means arranged to provide a magnetic field for controlling the switching of the armature, the permanent magnetic field producing means including elements positioned on both sides of the ends of the armature and at each end of the electromagnetic field producing means.

2. A polarized electromagnetic relay according to claim 1 having a sealed enclosure wherein the floating armature and the four contact elements are positioned within the enclosure, the said enclosure being positioned within the electromagnetic field producing means.

3. A polarized electromagnetic relay according to claim 1 wherein the freely movable armature is of metal and constitutes a permanent magnet.

4. In a polarized electromagnetic relay comprising a floating armature movable about its center of gravity, made from a magnetic electrically conducting metal, and held in stable contact positions by permanent magnet means and at least one control winding the field of which acts on the said armature to control the movement thereof to provide a required switching operation, the improvement comprising permanent magnets so arranged on both sides of the ends of the armature and in the longitudinal axis of the control winding at opposite ends of the armature that the action of the said magnets places the armature in the said axis in the absence of a field produced by the said winding, and four elements, which are made from nonmagnetic electrically conductive metal for making contact to a circuit to be switched, which are so positioned that diagonally opposed pairs of the elements are in contact with the opposite ends of the movable armature upon the movement of the armature about its center of gravity under the control of the field from the said winding and which constitute end of travel stops, wherein, in the absence of a field produced by the control winding, the armature is located in a position in which it is not in contact with any of the contact and stop elements.