US3626337A

US3626337A - Electromagnetic relay with permanent magnet latching

Info

Publication number: US3626337A
Application number: US59047A
Authority: US
Inventors: Harry Stanley Woodhead
Original assignee: International Standard Electric Corp
Current assignee: STC PLC
Priority date: 1969-09-18
Filing date: 1970-07-29
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: NL7013654A; ZA704527B; IE34267B1; BE756309R; IE34267L; GB1257698A; FR2062254A5; CH526856A; ES383726A1; DE2045831A1

Abstract

A diaphragm relay uses a paramagnetic diaphragm as part of the electromagnetic circuit and may also use the diaphragm as part of the electrical contact closing circuit. A third function is provided for the diaphragm herein. The diaphragm is also interposed within a permanent magnet circuit which acts to latch the diaphragm in an operated condition.

Description

United States Patent ELECTROMAGNETIC RELAY WITH PERMANENT MAGNET LATCHING 13 Claims, 12 Drawing Figs.

U.S. Cl 335/ 196, 335/177 Int. Cl H01h'l/00, HO 1h 9/00 [50] Field ofSearch 335/196, 151, 177, 179, 170

[56] References Cited UNITED STATES PATENTS 3,331,040 7/1967 Woodhead 335/196 3,467,923 9/1969 Woodhead 335/196 Primary ExaminerHarold Broome Atl0rneysC. Cornell Remsen, Jr., Walter J. Baum, Paul W.

Hemminger, Charles L. Johnson, Jr., James B. Raden, Delbert P. Warner and Marvin M. Chaban ABSTRACT: A diaphragm relay uses a paramagnetic diaphragm as part of the electromagnetic circuit and may also use the diaphragm as part of the electrical contact closing circuit. A third function is provided for the diaphragm herein. The diaphragm is also interposed within a permanent magnet circuit which acts to latch the diaphragm in an operated condition.

ll/IIIIIYI III/Y1 PATENTEU DEC 7197:

SHEET 1 [IF 5 PATENTEDUEC 719?: 3626337 SHEET 2 BF 5 PATENTEU 15c 71% $526,337

SHEET 3 BF 5 PATENTEDDEC H97! v 3626.837

SHEET u 0F 5 ELECTROMAGNETIC RELAY WITH PERMANENT MAGNET LATCIIING This invention relates to electromagnetic relays and is a modification of the invention described in our US. Pat. No. 3,331,040, for Miniature Diaphragm Relay, issued on July I l, 1967, to H. S. Woodhead, and assigned to assignee of the present invention.

That specification related to a particular configuration of relay having a contact unit, one wall of which was formed by an inner magnetic member housed in an aperture in an outer magnetic member, the inner magnetic member providing one relay contact while the other contact, a moving contact, was provided by a diaphragm. Magnetically holding relays which are subject of this invention either have the same configuration of contacts or a modification of that configuration in which the configuration has been modified to suit difierent contact operation requirements.

According to the invention there is provided a bistable polarized magnetically holding relay including two contact units disposed at opposite ends of a permanent bar magnet, one wall of each contact unit being formed by one or more inner magnetic members extending through and sealed in an aperture in an outer magnetic member by an nonmagnetic seal, and contained within each contact unit one or more moving contacts provided by laminae of magnetic material disposed substantially normal to the axis of the aperture, the lamina or laminae and the inner and outer magnetic members of each contact unit forming part of a first magnetic circuit which threads the permanent magnet, and the laminae being excluded from a second magnetic circuit which also threads the permanent magnet the laminae being capable of being brought into contact with or separated from cooperating fixed contacts by the pulsing of an operating winding so as to bring about a change in the amount of flux threading the laminae by the diversion of a proportion of the magnetic flux of the permanent magnet from threading one of said magnetic circuits to threading the other.

The features of the invention will be evident from the following description of relays which embody the invention in preferred forms. The description refers to the accompanying drawings in which:

FIG. 1 shows a section through a contact unit,

FIG. 2 shows the diaphragm forming the moving contact of the unit,

FIGS. 3, 4, 5, 7, and 9 show sections through alternative contact units.

FIGS. 6, 8, and 10 show the moving contacts of the contact units shown respectively in FIGS. 5,7, and 9,

FIG. 11 shows an alternative form of diaphragm moving contact and FIG. 12 shows a longitudinal section through a relay having a contact unit situated at each end ofa bar magnet.

The relays to be described are composed essentially of two contact units together with associated magnet circuitry and an operating winding. It will be shown that substantially the same configuration of magnetic circuitry and operating winding can be employed with the various types of contact unit which are described herein. Therefore it is convenient to divide the ensuing description into two parts, the first part relating to the different contact units, while the second part relates to the configuration of magnetic circuitry and operating winding.

The contact unit illustrated in FIG. 1 which is a first variant of the single ON/OF F contact unit, is built up from a glass-tometal seal 1 which serves to seal an inner magnetic member 2 inside the central aperture of an annular outer magnetic member 3 thereby both magnetically isolating and electrically insulating the inner magnetic member from the outer. A diaphragm 4 of magnetic material is secured at its periphery to the outer magnetic member so that it just clears the end face of the inner magnetic member which has a shallow hole bored in it to leave an annular contact surface 5. The diaphragm 4, which is shown in section in FIG. 1 and in plan in FIG. 2, is, in

its unstressed state, a plane disc having a peripheral region 6 linked by a number of slender arcuate arms 8 with a central region 7 which includes the contact-making area. These arms are formed by cutting in the diaphragm three slots 9 having a length much greater than their width and cut in the form of arcs or circles. This symmetrical arrangement serves to reduce the spring rate of the diaphragm, giving the central region 7 considerable freedom of movement by reducing the stress necessary to distort it, while at the same time ensuring that, when attracted towards the inner magnetic member by means of magnetic attraction, it is constrained to move substantially rectilinearly into contact with the end surface 5. The glass-tometal seal 1 the inner magnetic member 2 and the outer magnetic member 3 together form one wall of the contact unit which is completed by means ofa cap 10. This cap can be conveniently attached to the outer magnetic member by projection welding resulting in an hermetically sealed structure which can have any desired atmosphere sealed within it. The contacts are operated by means of an externally applied magnetic flux threading the inner magnetic member 2, and the diaphragm 4, and the outer magnetic member 3. The diaphragm 4 must, of course, be made of a magnetic material such as a nickel-iron alloy, and, in order to present a low-resistance path, may be plated with a good conductor such as silver. This may be over plated at least in the contact-making region with a layer having good contact properties, such as paladium or one of the other noble metals. The cooperating contact surface 5 of the inner magnetic member 2 may be similarly plated. These layers, besides improving the electrical contact properties of the contact members, also serve to provide thenecessary nonmagnetic spacer between them which prevents their magnetic parts from coming into intimate contact with each other. The outer magnetic member may be provided with an internal flange ll of magnetic material which serves to concentrate "any magnetic flux threading the diaphragm in its central region 7 so that the gap between the inner magnetic member 2 and the central region 7, and the gap between the central region 7 and the flange 11 are in series in the magnetic circuit. Under these circumstances any flux in this circuit exerts forces across these gaps which are in parallel, or in other words which are additive. If this flange II is dispensed when the cap 10 is made of magnetic material in order to provide an adequate return path for the flux between the central areas of the diaphragm and the outer magnetic member. External electrical connections to the contacts of the unit are made to the inner magnetic member 2 and to the outer magnetic member 3 or to the cap 10.

FIG. 3 illustrates another (or second) variant of the single ON/OFF contact unit, which differs from the first in that an increase of magnetic flux threading the unit is required to separate the contacts instead of being required to close them, as is the case in the first variant illustrated in FIG. 1. This second variant is identical with the first except in the following respects. Firstly, the seal 1 is not necessarily electrically insulating, as the inner magnetic member does not serve as a fixed contact, though it still has to be magnetically insulating. Secondly, the cap 10 is dispensed with and its place taken by a different construction consisting of an electrically conducting inner cap member 32 sealed in the central aperture of an outer cap member 33 by means of an electrically insulating seal such as a glass-to-metal seal 31. Thirdly, the inner cap member 32 is provided with a precious metal fixed contact surface 35 which is annular and which butts against the central region 7 of the diaphragm 4 slightly distorting it to provide the necessary contact pressure. The term distorting" is used here as elsewhere in this specification to denote straining which is within the elastic limit of the material. In the case of the diaphragm such distortion will be confined almost entirely to the arms 8. And fourthly, an insulating washer 36 is provided to prevent the diaphragm from coming into intimate magnetic contact with the inner magnetic member 2 External electrical connections to the contacts of this unit are made to the inner cap member 32 and to the outer magnetic member 3 or to the outer cap member 33.

The third variant of the contact unit is illustrated in FIG. 4. This variant is a single changeover contact unit which incorporates all the features of the first two variants except of the cap and the insulating washer 36. In this unit, as in the first variant, the seal 1 has to be both nonmagnetic and electrically insulating. External electric connections to the contacts of this unit are made to the inner magnetic member 2, to the inner cap member 32, and to the outer magnetic member 3 or to the outer cap member 33.

The fourth, fifth and sixth variants which will now be described are multiple contact versions of the second, first and third variants of contact units respectively. In order to demonstrate a variety of multiplicities of contact sets the examples to be described each have a different multiplicity. It should be apparent however that the particular multiplicity chosen for any particular variant is arbitrary, and no special significance should be attached to that choice. Instead of having a single diaphragm as the moving contact, each of the following variants has a number of substantially coplanar laminae having the basic form of sectors, which laid side by side form the rough outline of a disc. In the same way that the diaphragm has a contact-making area linked by arms to an outer area by which it is secured, so each lamina has an involute form consisting of a contact area linked by one or more arms to an anchorage area.

The fourth variant of contact unit, a two-pole ON/OFF contact unit, is illustrated in FIG. 5, and the arrangement and configuration of its laminae illustrated in FIG. 6. Its construction is identical with that shown in FIG. 3 except that two resilient laminae 54 are substituted for the diaphragm 4, and there are four terminals sealed through the central aperture of the outer cap member 33. Two of these terminals are anchorage posts 59, to which the laminae are secured, and the remaining two are fixed-contact members 52, each provided with a previous metal fixed contact surface which is annular and which butts against the contact-making region 67 of the lamina 54 slightly distorting it from the flat in order to provide the necessary contact pressure. The involute shape of the laminae is shown in FIG. 6, each lamina consisting of a contact-making area 67 linked to an anchorage area 66 by a single arm 68 which embraces one side of the lamina. FIG. 6 also shows in dotted detail the positions of the anchorage posts 59, and the annular contact surfaces of the contacts 52 in their relation to the laminae. Since the laminae are substituted for the diaphragm they must also be made of magnetic material, and may also be plated, like the diaphragm, to improve their conductivity and contact properties. External electrical connections to this contact unit are are made to the two anchorage posts 59 and the two fixed-contact members 52.

The fifth variant, which is illustrated in FIGS. 7 and 8, is a three-pole ON/OFF contact unit, and whereas the fourth variant requires an increase of magnetic flux threading the unit in order to separate the contacts; in this variant an increase of flux serves to bring the contacts together. FIG. 7 shows a section through one of the laminae when it is magnetically energized. This variant can be seen to be the multiple-contact version of the first variant described with reference to FIGS. 1 and 2. It is distinguished from that variant in the following respects. The diaphragm is replaced by three substantially coplanar laminae 74, each of which in its unstressed state is flat, and consists of a contact-making area 87 linked by two arms 88 to its anchorage area 86, by which it is secured to one of three anchorage posts 79, The anchorage posts together with the inner magnetic members 72 are sealed by the glassto-metal seal I in the central aperture of the annular outer magnetic member 3. The inner magnetic members 72, like the inner magnetic member 2 in FIG. 1, are formed with annular end faces 75 which provide the fixed-contact surfaces and which may be plated in a similar manner to the contact surface 5 to improve their contact properties. Where they project from the contact unit the inner magnetic members 72 are magnetically linked by a magnetic yoke 73 from which they are electrically insulated by means of electrically insulating sleeve 71. This magnetic yoke 73 is provided with a spigot 73a. In this variant the magnetic circuit which operates the contacts threads the magnetic yoke 73, from which it branches into the inner magnetic member 72, into the laminae 74, and then is reunited in its return path threading the cap 10 and the outer magnetic member 3. External electrical connections to this contact unit are made to the three anchorage posts 79 and the three inner magnetic members 72.

The sixth variant, which is illustrated in FIGS. 9 and 10, is a four-pole changeover contact unit which combines the features of the fourth and fifth variants. Each lamina 94, which in its unstressed state is flat, has a contact area 97 linked by two arms 98 to an anchorage area 96. External electrical connections to the contact unit are made to the four anchorage posts 99, the four inner magnetic members 92 and the four fixedcontact members 92'.

These contact units all possess the feature that they can readily be made in a hermetically sealed form. Although they include in their construction glass-to-metal seals, the construction is such that the seals can be made as one of the first steps of manufacture so that the relatively high temperature involved in their making does not affect items such as the diaphragm of laminae, which, like the permanent magnet and operating winding can be added at a later stage. The final sealing operation of the unit can be the sealing of one metal component to another and can be effected by a method such as projection welding which need heat the bulk of the contact unit scarcely at all.

It has been explained previously that the purpose of the slots in the diaphragm of FIG. 2 is to provide the diaphragm with slender arms linking the central region with the peripheral region so as to reduce the spring rate of the diaphragm. If a further reduction in spring rate is required it may not be practicable either to lengthen the tongues or to reduce their cross section. Referring again to the construction of diaphragm depicted in FIG. 2 it will be observed that if the central region of the diaphragm is displaced perpendicularly out of the plane of the peripheral region the tongues act as double-cantilever systems by virtue of the fact that their extremities are constrained to lie in parallel planes. Therefore the spring rate can be further reduced by modifying the construction so as to remove this constraint and so allow each tongue to act as a single cantilever. This constraint may be removed by adopting the construction of diaphragm illustrated in FIG. II, which may be used in any of the first three variants of contact unit. Such a diaphragm consists ofa disc from whose periphery protrude three arcuate tongues llI whose extremities are bent over to form U-shaped portions I12. When fitted in a contact unit the diaphragm is supported by these U-shaped portions, and when the disc is attracted towards the inner magnetic member the strain is taken up by the tongues which act as single cantilevers by virtue of the fact that they are able to pivot on their U-shaped extremities.

Next to be described is the configuration of magnetic circuitry and operating winding for a relay employing any of the above-described variants of contact unit. This configuration is essentially the same for all relays irrespective of which variant of contact is actually employed. By way of example a relay will now be described with reference to FIG. 12 which employs two first variant contact units.

Referring now to FIG. I2 two first variant contact units 120, such as shown in FIG. 1, are situated with their inner magnetic members 2 at opposite ends of a permanent bar magnet I21 from which the are electrically insulated by insulating washers 122. An electrically insulating sleeve 123 surrounds the permanent magnetic 121 while the inner magnetic members 2 project into collars 124 also of magnetic material. These collars are covered by electrically insulating sleeves I25, and together with the permanent magnetic I21, fit inside a tube 126 of magnetic material. A further insulating sleeve I27 covers this tube, and together with two insulating moldings 128, forms a bobbin for one or two operating windings 129. Connections to these windings 129 are made by way of terminals 130 embedded in the moldings 128, and connections to the contacts of the contact units are made by way of

terminals

131 and 132 connected to the inner and outer magnetic members respectively. The magnetic circuitry is completed by means of an outer cover member 133 of magnetic material which is sprung over the two outer magnetic members forming a magnetic path between them and also serving to partially enclose the winding protecting if from accidental damage.

This configuration provides two magnetic circuits threading the permanent magnet. In one of these circuits the flux enters the inner magnetic member of one contact unit. threads the diaphragm, and leaves the outer magnetic member by way of the cover, from which it enters the outer magnetic member of the other contact unit, threads its diaphragm, and returns to the permanent magnetic by way of its inner magnetic member. in the second circuit the flux bypasses the contacts, and instead enters the tube by way of one collar and leaves it by the other. The polyester sleeves 125 provide this second circuit with sufficient reluctance to cause a suitable proportion of the flux of the permanent magnet to thread the first circuit. To achieve a substantial contact force it is preferred to construct the relay so that the major proportion of this flux threads the second circuit. The division of the flux from the permanent magnet between the two magnetic circuits is determined in inverse proportion to their relative reluctances. When the diaphragms are in contact with their associated inner magnetic members the reluctance of the first magnetic circuit is less than when they are separated, and hence more of the flux threads the first circuit when the contacts are closed. The dimensions of the relay are so chosen that when the diaphragms are separated from their associated inner mag netic members there is insufiicient flux threading them to cause them to come together, but that when they have come together the additional flux threading them is sufficient to cause them to remain in that state. Under these conditions the relay may be operated by pulsing the operating winding. If the sense of a pulse applied to the winding is such as to cause the electromagnetically induced m.m.f. to augment the flux already threading the second magnetic circuit then there will be a corresponding reduction in the amount of flux threading the first. If the pulse is large enough this reduction will cause the contacts to be released. Conversely if the sense of the pulse is reversed it will produce an m.m.f. opposing the flux already threading the second magnetic circuit, and therefore additional flux will be caused to thread the first and so bring the contacts together.

It will be evident that while the above description of a relay has referred to one containing two of the first variant of contact units, either of both of these contact units can be replaced with any of the other variants having only one inner magnetic member. This will not necessitate having to change the basic configuration though small changes of dimensions may be required to match any differences of magnetic operating conditions required for operation and release of the contacts. Similarly either or both of the contact units can be replaced with ones having a plurality of inner magnetic members, in which case the spigots 73a of the magnetic yokes 73 of these contact units are designed to fit in the collars 124 of the relay in place of the inner magnetic members 2 of the contact units that they replace.

it is to be understood that the foregoing description of specific examples of this invention is not to be considered as a limitation of its scope.

lclaim:

l. A bistable polarized magnetically holding relay including two contact units disposed at opposite ends of a permanent bar magnet, each contact unit comprising a first magnetic circuit including an .inner magnet member, an outer magnetic member, and a contact member disposed therebetween, said inner magnetic member extending through and sealed in an aperture in said outer magnetic member by a nonmagnetic seal, said contact member comprising at least one moving contact comprised of laminae of ma netic material disposed substantially normal to the axis of t e aperture, means ad acent said first magnetic circuit for completing a second magnetic circuit threading the permanent magnet and inner magnetic member, magnetic winding disposed to develop flux for flow through both said magnetic circuits, means for mounting the laminae in said contact unit for movement into contact with or separated from cooperating fixed contacts in response to pulsing of said operating winding so as to bring about a change in the amount of flux threading the laminae by the diversion of a proportion of the magnetic flux of the permanent magnet from threading one of said magnetic circuits to threading the other.

2. A relay as claimed in claim I, wherein at least one side of the magnetic material of the laminae is faced with at least one layer of nonmagnetic material.

3. A relay as claimed in claim 1, wherein at least one contact unit contains only one moving contact, and moving contact being provided by a diaphragm whose central area forms the contact-making area of the contact.

4. A relay as claimed in claim 3, wherein each said diaphragm is in contact at its periphery with its associated outer magnetic member and has therein three or more apertures so formed that the central area of the diaphragm is linked with a peripheral area by three or more slender arcuate arms.

5. A relay as claimed in claim 3, wherein said diaphragm consists of a disc from whose periphery protrude three or more arcuate tongues whose extremities are free to pivot.

6. A relay as claimed in claim 5, wherein the free end of each arcuate tongue terminates in a U-shaped portion whose limbs are substantially at right angles to the disc.

7. A relay as claimed in claim 1, which includes at least one contact unit containing a plurality of moving contacts each having an involute form consisting of a contact-making area linked by one or more arms to an anchorage area by which it is secured to an anchorage post sealed through a wall of that contact unit.

8. A relay as claimed in claim 7, wherein the involute laminae of each contact unit are substantially coplanar.

9. A relay as claimed in claim 1, wherein the inner magnetic members form fixed contacts.

10. A relay as claimed in claim I, wherein the fixed contacts have annular contact surfaces.

11. A relay as claimed in claim 1, wherein there is structure for hermetically sealing one or more of the contact units.

12. A relay as claimed in claim l, wherein there is a tube of magnetic material which forms part of the second magnetic circuit and which surrounds the permanent magnet and which is itselfsurrounded by the operating winding.

13. A relay as claimed in claim 12, wherein there is a cover member of magnetic material which at least partially encloses the operating winding, and which magnetically links said tube with said outer magnetic members.

Claims

1. A bistable polarized magnetically holding relay including two contact units disposed at opposite ends of a permanent bar magnet, each contact unit comprising a first magnetic circuit including an inner magnet member, an outer magnetic member, and a contact member disposed therebetween, said inner magnetic member extending through and sealed in an aperture in said outer magnetic member by a nonmagnetic seal, said contact member comprising at least one moving contact comprised of laminae of magnetic material disposed substantially normal to the axis of the aperture, means adjacent said first magnetic circuit for completing a second magnetic circuit threading the permanent magnet and inner magnetic member, magnetic winding disposed to develop flux for flow through both said magnetic circuits, means for mounting the laminae in said contact unit for movement into contact with or separated from cooperating fixed contacts in response to pulsing of said operating winding so as to bring about a change in the amount of flux threading the laminae by the diversion of a proportion of the magnetic flux of the permanent magnet from threading one of said magnetic circuits to threading the other.

2. A relay as claimed in claim l, wherein at least one side of the magnetic material of the laminae is faced with at least one layer of nonmagnetic material.

9. A relay as claimed in claim l, wherein the inner magnetic members form fixed contacts.

10. A relay as claimed in claim l, wherein the fixed contacts have annular contact surfaces.

12. A relay as claimed in claim l, wherein there is a tube of magnetic material which forms part of the second magnetic circuit and which surrounds the permanent magnet and which is itself surrounded by the operating winding.