US3256402A

US3256402A - Switch relay for use in electric motors

Info

Publication number: US3256402A
Authority: US
Inventors: Clovis E Linkous
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1964-01-02
Filing date: 1964-01-02
Publication date: 1966-06-14
Anticipated expiration: 1983-06-14

Description

June 14, 1966 c. E. LINKOUS I 3,256,402

SWITCH RELAY FOR USE IN ELECTRIC MOTORS Filed Jan. 2, 1964 5 Sheets-Sheet 1 INVENTOR. C/ow's E. L frz/foas,

June 14, 1966 c. E. LINKOUS 3,256,402

SWITCH RELAY FOR USE IN ELECTRIC MOTQRS 5 Sheets-Sheet 2 Filed Jan. 2, 1964 @My 6 m T .n r N ho W5 wu June 14, 1966 c. E LINKOUS ,402

swxwca RELAY FOR USE IN ELECTRIC MOTORS Filed Jan. 2, 1964 5 Sheets-Sheet 3 it-ms ws M5 INVENTOR.

C ov/Is ET L/lvfl aus,

BWAmM United States Patent SWITCH RELAY FOR USE IN ELECTRIC MOTORS Clovis E. Linkous, Fort Wayne,.Ind., assignor to General Electric Company, a corporation of New York Filed Jan. 2, 1964, Ser. No. 335,284 .12 Claims. (Cl. 200-87) These relays customarily include a core structure and a cooperating moveable armature which defines a variable magnetic air gap with the core and carries means for actuating the movable contact of the relay. Unfortunately, the relays are usually rather complicated and costly in design to achieve a longevity over 100,000 cycles of operation, far less than the number of cycles required to approach the life expectancy of the motor in which they are used. These relays normally require mechanical impact elements for separating the movable and stationary contacts in an attempt to prevent the occurrence of contact welding. Further, the more satisfactory prior art relays incorporate certain close toleranoe parts; e.g., the mechanical impact element and armatures, in an attempt to attain a life expectancy of at least 100,000 operations. Such relays may even include an expensive and complicated calibration system in an effort to obtain a controlled movement of the armature which does not vary substantially between one operation and the next. Another problem with this type of relay is the noise it produces during operation which is particularly noticeable and objectionable when the relay is employed in motors used for domestic applications, such as in typewriters, appliances, and the like.

It is therefore a general object of the present invention to provide an improved switch relay especially adapted for use in electric motors and it is a more specific object to provide such relay which overcomes the deficiencies mentioned above.

It is still another object of the invention to provide a relatively inexpensive relay which incorporates easily assembled components, is quiet in operation, and provides a positive and consistently uniform motion of the movable switch contact.

It is another object of the invention to provide a switch relay which is compact and simple in design, rugged in construction, does not require close toleranced mechanical impact elements, yet is capable of well over 1,000,000 cycles of trouble-free and generally uniform operation.

In carrying out the objects of the present invention in one form, I provide a dynamoelectric machine having start and main windings with an improved switch relay for controlling the circuit of the start winding. The relay includes a core formed of magnetic material having at least twoupstanding leg sections joined together at one end by a yoke section. One of the ends of the legs, remote from the yoke section, pivotally mounts an armature for swinging its free end toward and away from the other leg sections. At least one of the relay legs accommodates a coil which is adapted to be energized during operation of the motor for actuating the armature. A generally U-shaped spring is connected under compression between the free end of the armature and a support for biasing the free end of the armature away from ice the relay core. A stationary switch contact is spaced from the side of the armature remote from the core,.with a second contact being movably carried by a cantilever spring which normally biases the second contact into engagement with the first contact to provide a normally closed set of contacts.

The armature and cantilever spring are connected together for movement by a lost motion connection such that both springs apply a bias to the armature when the contacts are in a nonengaging relation, with the springs together defining a net negative spring constant, but only the U-shaped spring applies a bias to the armature once the contacts are closed. The relay also includes calibrating means which simultaneously regulates the bias of the U-shaped spring and the magnetic air gap between the armature and the core. A small change in the calibrating air gap has a large controlling afiect on the voltage at which the armature is pulled down toward the core.

When the contacts are in the closed position, the lost motion connection permits unimpeded movement between the armature and the second contact from the fully open position of the armature to the point at which the armature makes a firm connection with the cantilever spring which carries the movable contact. Thus, when the coil is energized and the armature overcomes the bias of the U-shaped springs and moves from the fully open to firm connection positions, the armature engages the cantilever spring with an impact to separate the contacts with a sudden motion. This engagement is achieved due to the momentum imparted to the armature before engagement and serves to breakrwelds which might occur in the switch contacts.

The subject matter which I regard as my invention, is particularly pointed out and distinctly claimed in the concluding portion of this specification. My invention itself, however, both as' to its organization and method of operation, together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing.

In the drawing:

FIG. 1 is a side elevational view of a normally closed switch relay assembly embodying one form of my invention;

FIG. 2 is a view taken along line 2-2 in FIG. 1;

FIG. 3 is an enlarged, fragmentary view of a portion of the relay assembly of FIG. 1, showing the relay components intheir respective positions at the instant that the switch contacts either become engaged or just prior to their separation, depending upon the direction of armature travel;

FIG. 4 is a view similar to FIG. 3 revealing the same components, with the armature in the fully closed position and the contacts in the open contact position;.

FIG. 5 is a schematic diagram showing the relay assembly of FIG. 1 connected in the start winding circuit of a single phase split phase electric motor;

FIG. 6 is a graphic presentation of the forces exerted on the relay armature by the relay spring system of the relay assembly of FIG. 1 plotted against the distance across the magnetic air gap at the end of the armature remote for its pivot;

FIG. 7 is a side elevational view of a switch relay assembly incorporating another form of my invention;

FIG. 8 is a view taken along line 8-8 in FIG. 7 and;

FIG. 9 is a view taken along line 99 in FIG. 7.

Referring now to the drawings in more detail, and in particular to the embodiment illustrated by FIGS. 1-6 inclusive, one form of my improved switch relay is .generally identified by character numeral 10. The relay is provided with an E-shaped core structure 11 formed of magnetic material such as iron or steel, having three spaced apart

magnetizable leg sections

12, 13, and 14 integrally joined at one end by an elongated magnetic yoke section 15. Outermost leg section 12 has its free end 12a, remote from yoke section 15, extending above free ends 13a and 14a of the remaining two leg sections (as viewed in FIG. 1) and is formed with means for pivotally mounting one end of an elongated armature assembly or mechanism, denoted by numeral 21. This pivotal connection takes the form of an enlanged, generally U-shaped notch 16, furnished in the edge of leg portion 12a which faces middle leg 13. The armature mechanism 21 has a rectangular slot 22 (FIG. 2) with the smaller size wall 23 of the slot being received within notch 16 for providing a fulcrum pivotal support of mechanism 21 In order to facilitate both the pivotal action of mechanism 21 and the assembly of the parts, the longer wall of slot 22 is dimensionally greater than the width across leg portion 12a above notch 16.

Mounted on the middle leg 13 of core 11 is an excitation winding or coil 18 which is adapted to be energized in a manner to be described in detail hereinafter. The coil is suitably insulated from the core as by Mylar, fiber board, or other electrical insulation. A shading coil 20 incircles outermost leg section 14, remote from the pivot of the armature, and functions to delay a change of flux through the shaded leg section in the well-known way.

Turning now more specifically to the illustrated construction of armature mechanism 21, it is provided with a magnetizable elongated element 24 which has its free end 25 arranged to swing toward and away from free end 14a of leg section 14 in response to the magnetization of the core by coil 18 and defines a magnetic air 'gap therewith.

electrically conducting, spring arm or blade 29 which applies a continuous bias to contact 28 toward the normally closed engaging position shown in FIG. 1. Arm 29 has its end 31 suitably secured as by a rivet 40 (FIG. 2) onto a support best seen in FIG. 1. The support is generally indicated by numeral 30 and for purposes of disclosure is of the type disclosed and claimed in my copending and concurrently filed patent application, Serial No. 335,243 filed January 2, 1965. As described in that application the support is a single piece, molded of thermoresponsive material. In the present exemplification it serves to mount core 11 of the relay as well as

switch contacts

26 and 28 within a chamber 32.

Returning once again to the description of armature mechanism 21, a generally U-shaped toggle spring 35 is employed to bias the free end 25 of the assembly away from core leg section 14. In the first embodiment, shown in FIGS. 1-6, this is achieved by securing a metal bracket 36 on the top (as viewed in FIG. 1) of element 24 as by a number of spot welds, and bending bracket extension 37 downwardly over the end of element 24. The toggle springis confined under compression between and bears upon generally opposed abutments or

spring seats

38, 39 respectively furnished in bracket extension 37 and a stationary support 41. These seats provide fulcrums upon which the spring rocks during operation of the armature mechanism. This spring 35 also functions to maintain the armature 21 in an assembled relation in notch 16 by applying a force to bracket 36, and hence -nism when disposed in the closed or operated position shown in FIG. 4. The configuration of the U for the spring may also be designed for assisting in the achievement of this purpose.

I prefer to connect armature mechanism 21 and the movable contact 28 for movement together by a lost motion connection. That is to say, for a preselected initial travel of the armature from its fully open position, it should be free to move toward leg section 14 without movement being imparted to movable contact 28. Thus, referring to FIG. 1, when the armature mechanism 21 is in the fully open or unoperated position and the movable contact 28 is in engagement with fixed contact 26, armature end 25 is permitted to accelerate over a significant distance as it overcomes the bias of spring 35 before the armature makes a firm driving connection with contact 28. In order to accomplish this end, a U-shaped tab 44 may be stamped out from bracket 36 prior to its assembly onto element 24 and bent into an L-shaped extension such that a portion of the tab is arranged to overlie the extremity of spring blade 29 adjacent contact 28 in a preselected spaced apart manner, denoted by letter a in FIG. 1.

Consequently, upon pivotal movement of armature end 25 downwardly toward leg section 14, away from its fully open position, the armature is free to move distance a without interference from spring blade 29, gaining a significant and a predetermined momentum before extension 44 engages the spring blade. This in turn produces an impact type engagement between the armature mechanism 21 and the cantilever blade carrying contact 28 (see FIG. 3) to impart sudden motion to that contact away from the fixed contact. If the contacts resist opening, as might occur in a contact welding condition, a high impact force will be developed and transmitted to contact 28 which overcomes the condition to insure an opening of the contacts in response to downward movement of the armature.

FIG. 5 schematically shows the switch relay 10 just described operatively connected in a winding circuit of a single phase split phase induction motor having a conventional stator provided with a main winding 51 in parallel with a start winding 52. In particular, fixed contact 26 of relay 10 is connected by a standard quick connect terminal 53 to one side of the start winding which has its other side attached to terminal 54 of a three pronged unitary terminal post 55 (carried by support 30) which in turn, has another terminal 56 attached to one side of a power supply line 57. Relay contact 28 is connected to the other side of the power supply line 58 through

terminals

59 and 60 of post 61 and a conventional, manually operated control switch 62.

Terminals

63 and 64 respectively of posts 61 and 55 serially connect the main winding to the power supply lines. Coil 18 of the relay is energized through

conductors

65 and 66 which are attached by crimped connectors 67 between the wire terminations of that coil and those of a sensing coil 68 arranged in the start axis of the start winding 52.

Further features and advantages of relay 10 will become more apparent from a description of the manner in which the relay functions to control the circuit of start winding 52 during operation of the motor. With the relay components and manual switch disposed in the relative positions shown in FIGS. 1 and 5, the start winding 52 and main winding 51 are energized in parallel across power lines 5758. As the speed of the motor increases, the voltage induced in sensing coil 68 becomes larger and is .75 applied to relay coil 18. This in turn causes an attraction on the relay armature element 24 proportional to the square of the applied voltage. It will be recalled from the previous explanation of the relay components seen in FIG. 1 that the armature is held in its fully open position solely by the bias of toggle spring 35. Thus, when the magnetic force of attraction on the armature created by the relay coil 18 and core 11 exceeds the bias of this spring, armature end 25 will be puled down toward the core without a corresponding movement of normally closed contact 28 for a distance a by virtue of the lost motion connection between these components.

The point at which the contacts are opened by the armature is in effect a so-called cutout speed of the motor. This may readily be calibrated in relay by a screw 71 (FIG. 1) which is threadingly accommodated in a suitable hole in support 30 such that the end of the screw engages bracket 36 to limit or control the exact dimension of a. Rotation of screw 71 results in a linear change in its position relative to the armature 21 and de fines the fully open position of the armature. Consequently, the air gap dimension of the relay is regulated with a resulting control of the magnitude of the magnetic attraction across the air gap required to initiate downward motion of armature 21. It will be remembered that, as the distance across the air gap diminishes, the attraction on the armature or magnetic force becomes greater, accelerating the swinging motion of the armature toward the closed position (zero air gap) evidenced in FIG. 4. Conversely, the spring force on armature 21 decreases as the air gap decreases. Thus, a small change in the calibrated air gap of relay 10 has a large effect in the value of the voltage at which the armature will be pulled down.

As the relative positions of the relay components seen in FIG. 3, a firm connection is made between bracket extension 44 and the cantilever spring blade 29 of contact 28. The impact which is obtained in a simple, direct and highly effective way has already been discussed. Further swinging movement of armature end 25 towards the fully closed position shown in FIG. 4, due to the progressively increasing magnetic attraction as the air gap decreases in size, overcomes the combined bias of

spring

29 and 35 to open

contacts

26, 28, and the start winding circuit.

Under these circumstances, the motor operates under running conditions with only the main winding 51 energized.

If the motor stalls for any reason and the speed is reduced until the voltage induced in sensing coil 68 finally reaches 'a level sufliciently low such that the magnetic attraction on the armature mechanism 21 is less than the combined or net spring bias or upward force placed upon armature end 25 by

springs

29 and 35, a cutback speed or condition is reached. At this time, springs 29 and 35 drive the armature to the position seen in FIG. 3 and

close contacts

26 and 28 to energize the start winding 52. The.

motor begins one again to develop starting torque and, so long as cutback of the motor occurs between zero speed and the cutout speed, there is no need to accurately control the exact cutback speed at which the relay operates. However, if such control becomes desirable in the embodiment of FIGS. 1-5, accurate regulation may be accomplished by merely adjusting the elevation of seat 39 in support bracket 41 relative to opposed seat 37.

The following is one example of how the present invention has been carried out in actual practice. Several relays 10 were constructed in accordance with the illustrated embodiment of FIGS. 1 through 5 inclusive and tested in a /3 horsepower, resistance split, single phase alternating current induction motor having four poles. The typical spring force-deflection characteristic of these relays is set out in the graph form of FIG. 6, with the spring forces biasing the armature being plotted against the distance across the relay air gap.

From an inspection of FIG. 6, it will be observed that in the tested relays of the exemplification the normal open position of the armature (with the contacts being closed) provides an air gap of approximately .075 inch A firm connection between the armature and spring 29 of contact 28 is made at an air gap of approximately .025. Above this point, only spring 35 applies a bias (curve A) to the armature. Thus, the armature 21 is allowed to accelerate over a distance a of about 0.05 inch before it engages spring '29 to produce a significant momentum and downward impact on contact 28 for opening the contacts. At an air gap of 0.025 inch and smaller, both springs produce a net force on the armature denoted by the letter B.

As suggested by the graph of FIG. 6 the net spring forces with a small air gap are less than those for a large air gap so the spring system is essentially a negative spring constant. Since the voltage induced in sensing coil 68 after the contacts have been opened is merely /a to /2 as great as that when the contacts are closed, just prior to their opening, that is approximately under the same speed conditions, it is extremely desirable, if not essential, that the springs have a net negative spring constant. In the embodiment of FIGS. 1-5, springs 29 and 35 always have an aiding or augmenting rather than a bucking relationship so that they also produce a continuous and positive bias on the armature in a direction away from coil 11. Further, as seen in FIG. 6, springs 29 ated satisfactorily well over 1,000,000 cycles with a -gen Further, they were erally uniform and quiet operation. relatively inexpensive to fabricate, the components being easily assembled together, and the mechanical impact elements produced a highly satisfactory, sudden separation of the contacts time and again in spite of the fact that the relay components were not held to close toler-' ances. Moreover, the relays were compact and simple in construction and provided a positive and consistently uniform motion of the movable switch contact 28 and relay armature mechanism 21.

FIGS. 7, 8, and 9 illustrate a second embodiment of my invention in which identical parts to those shown in FIGS. l-5 inclusive are identified by the same reference numbers. The switch relay of this second embodiment is generally denoted by numeral and like the first embodirnent, has a magnetic core formed essentially with three spaced apart

leg sections

81, 82, and 83, integrally united by yoke section 84. Outermost leg section 81a has a generally U-shaped notch 85 for pivotally mounting one end of a magnetizable, generally L-shaped, armature mechanism 91. Each of the other two leg sections accommodates similarly wound coils 92 and 93, serially connected, which together actuate armature 91. Suitable insulation 86 is disposed between each coil and the core for insulation reasons. FIG. 7, of

legs

82 and 83 are each provided with a U- shaped notch 87 in which is arranged a shading coil can be obtained with the same on a lower power or watts dissipation. This thermally desirable condition is particularly beneficial when my relay is utilized in electric equipment, such as the electric motor of the exemplification where the overall operating temperature is a limiting factor on the type of components which may be in- I corporated in the equipment.

With respect to the construction of armature mechanism 91 of the second embodiment, it is a single piece element having an enlarged, generally rectangular slot -97 The upper edges, as viewed in extending from notch 85 to a point adjacent leg portion 82a of the middle leg section 82. A generally U-shaped spring 101 has its ends held under compression between a seat in bar projection 102, made integral with coil 95, and a generally opposed seat formed in leg extension 98 of the armature, that is, at its free end which is spaced outwardly from outermost leg section 83. This spring forces engagement between wall 99 of armature slot 97 and leg notch 85 for pivotal action and applies an upward bias to the free end of armature 91, away from the core or leg section 83.

In the second embodiment, the movable contact 28 is biased to a normally closed position relative to fixed contact 26 by a cantilever spring 103 which has its one end 104 secured to support 30 in the vicinity of, but above, the fulcrum for the armature 91. The lost motion connection between the armature and spring 103 is formed by projecting the free end of armature 91 through an enlarged rectangular opening 105 (FIG. 9) provided in a depending leg 106 of the cantilever spring 103. As the free end of armature 91 is swung between the broken position shown in FIG. 7, its fully open position (

contacts

26, 28 being closed) and its fully closed position shown by the solid lines in FIGS. 7 and 9, the bottom of the armature in the spring opening 105 engages the bottom wall of the opening.

Like the first embodiment, between the fully open position of the armature 91 and the point of engagement with the cantilever spring, the magnetic attraction on the armature must overcome only the bias of the U-shaped spring 101. Thus, the free end of the armature obtains a significant momentum and provides a sudden, impacttype separation of

contacts

26, 28 when engagement is made. As the air gap between the core legs and armature 91 decreases between the point of engagement and fully closed position of the armature, this magnetic attraction is further increased to overcome the bias of both springs. Essentially, then, this operation and spring system is similar to that of the FIGS. 16 and when connected in the circuit of FIG. 5, will operate in the manner previously outlined for the first embodiment. Here, again, the resetting forces on the armature are the sum of the individual forces of the two springs until the contacts are closed whereupon the U-shaped spring, applying a gradually increasing force on the armature, returns it to its fully open position. However, in the second embodiment, although the core and coils produce a greater magnetic attraction for a given core size than the first embodiment, it is nonetheless slightly less expensive to manufacture. Note, for instance, the extremely simple construction of armature 91. In addition, cutback of the relay 80 may be readily calibrated by connecting a screw 109 to cantilever spring 103 by a threaded engagement indicated at 110 such that turning of the screw through support 30 will in efiect adjust the pivot of spring 103 and control its deflection characteristic as required for a particular application.

From the foregoing, it will be appreciated that relay 80 incorporates the same desirable features and attributes ing leg sections integrally joined together at one end thereof by a yoke section, the end of one of said legs remote from said yoke section pivotally mounting an armature for swinging the free end thereof toward and away from one of the other leg sections respectively between closed and open armature positions therewith, a coil accommodated on at least one leg section adapted to be energized during operation of the motor for actuating said armature, a generally U-shaped spring connected between the free end of said armature and a support and biasing the free end of said armature in a direction generally away from said other leg section, a first switch contact spaced from side of said armature remote from said core, a second contact movably mounted adjacent said first contact to provide closed and open contact positions with respect to said first contact, a second'spring normally biasing said second contact into engagement with said first contact, lost motion means connecting said armature and second contact for movement together, said generally U-shaped spring and second spring applying a bias to said armature when said contacts are in a nonengaging relation with the net spring force on said armature being generally greater when said contacts are closing than when said contacts are in the open position, the lost motion means between said armature and second contact being disengaged when said first and second contacts are in the closed position and becoming engaged with an impact as the armature overcomes the bias of said springs, gains momentum to cause sudden separation of said contacts and drives said second contact into the open contact position as the free end of the armature swings toward the closed armature position.

2. A switch relay having normally closed contacts for use in an electric motor, the relay comprising a core formed of magnetic material, an armature pivotally mounted adjacent said core for swinging the free end thereof toward and away from the core respectively between closed and open armature positions, a winding accommodated on said core adapted to be energized during operation of the motor for actuating said armature, a generally U-shaped spring connected to the free end of said armature and to a support, said spring continuously biasing the free end of said armature in a direction generally away from said core, a first switch contact spaced from the side of said armature remote from said core, a second contact movably mounted adjacent said first contact to provide open and closed contact positions While in accordance with the Patent Statutes, I have described what at present is considered to be the preferred embodiments of my invention, it will be obvious to those skilled in the art that numerous changes and modifications may be made therein without departing from the invention and it is therefore aimed in the appended claims to cover all such equivalent variations as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent to the United States is:

1. A switch relay having normally closed contacts for use in an electric motor, the relay comprising a core formed of magnetic material having at least two upstandwith respect to said first contact, a second spring normally biasing said second contact into engagement with said first contact, calibrating means engaging said second spring for regulating the bias thereof, said armature having a lost motion connection with said second contact, calibrating means for controlling the lost motion in said connection between said armature and said second contact, said generally U-shaped and second springs applying a bias to said armature when said contacts are in a nonengaging relation with the net spring force on said armature being generally greater when said contacts are closing than when said contacts are in the open position, said lost motion connection between said armature and second contact being disengaged when said first and second contacts are in the closed position and becoming engaged with an impact as the armature overcomes the bias of said springs to cause sudden separation of said contacts and to drive the second contact into the open contact position as the free end of the armature swings toward the closed armature position.

3. A switch relay having normally closed contact comprising a core formed of magnetic material, an armature pivotally mounted adjacent said core for swinging a free end thereof toward and away from the core respectively between closed and open armature positions, electromagneticmeans adapted to be energized for actuating said armature, a generally U-shaped spring connected between said free end of said armature and a support,

said spring continuously biasing the free end of said armature in a direction generally away from said core,

first switch contact means spaced from the side of saidv armature remote from said core, second switch contact means including a cantilever spring having one end firmly supported, the free end of said cantilever spring projecting between said armature and said first contact means and normally biasing said second contact means into engagement with said first contact means, lost motion means connecting said armature and cantilever spring for joint movement from said closed contact position to said open contact position, said U-shaped spring and cantilever spring applying a bias to said armature when said first and second contact means are in a nonengaging relation, said anmature'and said cantilever spring being disengaged when the free end of the armature is in the open position, said armature and cantilever spring becoming firmly connected as said armature overcomes the bias of both springs, gains momentum and makes impact with said cantilever spring to cause a sudden separation of said first and second contact means, said lost motion means effecting a greater armature travel during its disengagement from said cantilever spring'than during the connection of said armature and cantilever spring for movement together.

4. A switch relay comprising a core formed of magnetic material having at least two upstanding leg sections, an armature pivotally mounted for swinging a free end thereof toward and away from one of the leg sections and defining an air gap therewith, a winding accommodated on at least one leg section adapted to be energized for actuating said armature, a first spring connected between said armature and a support and biasing the free end of said armature away from said one leg section, a first switch contact spaced from said armature, a cantilever spring having one end rigidly mounted and carrying a second contact for movement between closed and open contact positions relative to said first switch contact, said cantilever spring biasing said second contact toward said first contact, means connecting said armature and said cantilever spring for concurrent movement, said first spring and cantilever spring together defining a net negative spring constant and applying a bias to the free end of said armature when said contacts are in a nonengaging relation, the net spring force on said armature being generally greater when said relay air gap is maximum than when said air gap is a minimum.

5.'A switch relay comprising a core formed of magnetic material, an armature pivotally mounted for swing 'ing the freeend thereof toward and away from said core and defining an air gap therewith, electromagnetic means for actuating said armature, a first snap acting spring connected to said armature and to a stationary support and continuously biasing the free'end of said armature in a direction generally away from said core, a first switch contact spaced from said armature, a second contact movably disposed adjacent said first contact, a second spring connected to said second contact for biasing it toward said first contact, said first and second springs together defining a net negative spring constant, calibrating means for regulating the bias of at least said first spring, and means connecting said armature and said second contact for joint movement, said first and second springs applying a bias to said armature when said contacts are in a nonengaging relation.

6. A switch relay having normally closed contacts for use in an electric motor, the relay comprising a core formed of magnetic material, an armature pivotally mounted adjacent said core for swinging the free end thereof toward and away from the core to define an air gap therewith, a winding accommodated on said core adapted to be energized during operation of the motor for actuating said armature, a generally U-shaped spring connected to the free end of said armature and to a sup port, said spring-continuously biasing the free end of I said armature away from said core, a first switch contact spaced from the side of said armature remote from said V core, a second contact movably mounted adjacent said first contact to provide open and closed contact positions with respect to said first contact, a second spring normally biasing said second contact into engagement with said first contact, calibrating means engaging said second spring for regulating the bias thereof, said armature having a lost motion connection with said second contact, calibrating means for controlling the lost motion in said connection between said armature and said second contact, said generally U-shaped and second springs applying a bias to said armature when said contacts are in a nonengaging relation with the net spring force on said armature being generally greater when said relay air gap is maximum than when said air gap is a minimum, said lost motion connection between said armature and second contact being disengaged when said first and second contacts are in the closed position and becoming engaged with an impact as the armature overcomes the bias of said springs and to cause sudden separation of said contacts.

7. A switch relay having normally closed contacts for use in an electric motor, the relay comprising a core formed of magnetic material having at least two leg sections joined together at one end thereof by a yoke section, the end of one of said legs remote from said yoke section pivotally mounting an armature for swinging the free end thereof toward and away from one of the outermost leg sections to define an air gap therewith, an electromagnetic winding accommodated on at least one leg section adapted to be energized during operation of the motor for actuating said armature, a generally U-shaped spring connected to the free end of said armature and to a support, said spring continuously biasing said armature in a direction generally away from said one outermost leg section, a first switch contact spaced from the side of said armature remote from said core, a second contact carried by a cantilever spring between said first contact and said armature for movement between open and closed contact positions with respect to said first contact, said cantilever spring having one end firmly supported with the other end projecting generally toward the pivot of said armature and normally biasing said second contact into engagement with said first contact, said armature including an extension overlying a part of said cantilever spring adjacent said second contact, said U-shaped and cantilever springs applying a bias to said armature when said contacts are in a nonengaging relation with the springs together defining a net negative spring constant, said armature extension being in spaced relation with said cantilever spring when said first and second contacts are in the closed position and engaging said cantilever spring with an impact as said armature overcomes the bias of both springs and gains momentum to cause a sudden separation of said contacts.

8. A switch relay having normally closed contacts for use in an electric motor, the relay comprising a core formed of magnetic material having at least two upstanding leg sections joined together at one end thereof by a yoke section, a generally L-shaped armature having the end of the longest leg pivotally attached to the end of one of said legs remote from said yoke section for swinging the free end thereof toward and away from one of the outermost leg sections to define an air gap therewith, an electromagnetic winding accommodated on at least one leg section adapted to be energized during operation of the motor for actuating said armature, a generally U- shaped spring connected between the shorter leg of said armature and a support, said spring biasing the free end of said armature in a direction generally away from said one outermost leg section, a first switch contact spaced from the sideof said armature remote from said core, a cantilever spring carrying a second contact and normally biasing said second contact into engagement with said first contact, said cantilever spring having an extension formed with a slot at its free end, said armature projecting through said slot and making a lost motion connection therewith, said U-shaped spring and cantilever spring conjointly applying a bias to said armature when said contacts are in a nonengaging relation with the springs together defining a net negative spring constant, said spring extension and armature having a loose connection when said first and second contacts are in the closed position, said armature engaging said cantilever spring extension with an impact to make a firm connection therewith as said armature overcomes the bias of both springs and gains momentum to cause a sudden separation of said contacts.

9. A switch relay comprising a core formed of magnetic material, an armature pivotally mounted for swinging a free end thereof toward and away from said core and defining an air gap therewith, electromagnetic means for actuating said armature, a first spring connected to said armature and to a support, said spring applying a force on said armature to bias the free end of said armature in a direction generally away from said core, a first switch contact spaced from said armature, a second contact disposed adjacent said first contact and movable between closed and open contact positions relative to said first contact, a second spring connected to said second contact for biasing it toward said closed contact position, and means connecting said armature and said second contact for joint movement between said closed and open contact positions, the biasof said first spring progressively increasing as said armature air gap increases for closing said contacts, said second spring applying a gradually decreasing bias to said armature as said second contact moves from said open to said closed contact positions. 7

10. The switch relay of claim 9 in which the spring force applied to said armature by said second spring is greater than the spring force'of said first spring at the open contact position but is less than the spring force of said first spring at the closed contact position, said first and second springs together defining a net negative spring constant.

11. The switch relay of claim 3 in which said armature includes a magnetic element and said lost. motion means comprises a bracket mounted to the side of said element remote from the core, said bracket having an L-shaped extension bent away from said element and overlying the free end of said cantilever spring, said L-shaped extension being disengaged with said cantilever spring when said armature is in the open armature position.

12. The switch relay of claim 3 in which said cantilever spring includes a depending extension at the free end thereof, said lost motion means comprises an enlarged slot formed in said extension, with a portion of said armature projecting through said enlarged slot, said extension and armature having a loose connection when said first and second contact means are in engagement with one another to provide lost motion for said lost motion means.

References Cited by the Examiner UNITED STATES PATENTS 2,585,684 2/ 1952 Roggenstein 20087 3,007,062 10/1961 Teasell 3071 12 3,165,607 1/1965 Hogan 200-87 FOREIGN PATENTS 833,686 4/1960 Great Britain.

' References Cited by the Applicant UNITED STATES PATENTS 1,621,056 3/ 1927 Bradshaw.

2,285,936 6/1942 Mishelevich. 2,292,497 8/ 1942 Vradenburgh.

2,326,760 8/1943 Clare. 2,527,220 10/ 1950 Hughes.

2,808,553 10/1957 Clark. 2,892,050 6/ 1959 Fisher.

2,896,041 7/ 1959 Schwancke.

2,897,308 7/ 1959 Fergus.

BERNARD A. GILHEANY, Primary Examiner.

J. J. BAKER, Assistant Examiner.

Claims

1. A SWITCH RELAY HAVING NORMALLY CLOSED CONTACTS FOR USE IN AN ELECTRIC MOTOR, THE RELAY COMPRISING A CORE FORMED OF MAGNETIC MATERIAL HAVING AT LEAST TWO UPSTANDING LEG SECTIONS INTEGRALLY JOINED TOGETHER AT ONE END THEREOF BY A YOKE SECTION, THE END OF ONE OF SAID LEGS REMOTE FROM SAID YOKE SECTION PIVOTALLY MOUNTING AN ARMATURE FOR SWINGING THE FREE END THEREOF TOWARD AND AWAY FROM ONE OF THE OTHER LEG SECTIONS RESPECTIVELY BETWEEN CLOSED ADN OPEN ARMATURE POSITIONS THEREWITH, A COIL ACCOMMODATED ON AT LEAST ONE LEG SECTION ADAPTED TO BE ENERGIZED DURING OPERATION OF THE MOTOR FOR ACTUATING SAID ARMATURE, A GENERALLY U-SHAPED SPRING CONNECTED BETWEEN THE FREE END OF SAID ARMATURE AND A SUPPORT AND BIASING THE FREE END OF SAID ARMATURE IN A DIRECTION GENERALLY AWAY FROM SAID OTHER LEG SECTION, A FIRST SWITCH CONTACT SPACED FROM SIDE OF SAID ARMATURE REMOTE FROM SAID CORE, A SECOND CONTACT MOVABLY MOUNTED ADJACENT SAID FIRST CONTACT TO PROVIDE CLOSED AND OPEN CONTACT POSITIONS WITH RESPECT TO SAID FIRST CONTACT, A SECOND SPRING NORMALLY BIASING SAID SECOND CONTACT INTO ENGAGEMENT WITH SAID FIRST CONTACT, LOST MOTION MEANS CONNECTING SAID ARMATURE AND SECOND CONTACT FOR MOVEMENT TOGETHER, SAID GENERALLY U-SHAPED SPRING AND SECOND SPRING APPLYING A BIAS TO SAID ARMATURE WHEN SAID CONTACTS ARE IN A NONENGAGING RELATION WITH THE NET SPRING FORCE ON SAID ARMATURE BEING GENERALLY GREATER WHEN SAID CONTACTS ARE CLOSING THAN WHEN SAID CONTACTS ARE IN THE OPEN POSITION, THE LOST MOTION MEANS BETWEEN SAID ARMATURE AND SECOND CONTACT BEING DISENGAGED WHEN SAID FIRST AND SECOND CONTACTS ARE IN THE CLOSED POSITION AND BECOMING ENGAGED WITH AN IMPACT AS THE ARMATURE OVERCOMES THE BIAS OF SAID SPRINGS, GAINS MOMENTUM TO CAUSE SUDDEN SEPARATION OF SAID CONTACTS AND DRIVES SAID SECOND CONTACT INTO THE OPEN CONTACT POSITION AS THE FREE END OF THE ARMATURE SWING TOWARD THE CLOSED ARMATURE POSITION.