Title:
Two-stage relay
United States Patent 2211701


Abstract:
The present invention relates to improvements in electrically operated devices particularly electromagnets and control systems embodying improved forms of such devices. More specifically, the invention has to do with and has as its object the provision of electromagnets or relays which may...



Inventors:
Mcgrath, William L.
Application Number:
US24232938A
Publication Date:
08/13/1940
Filing Date:
11/25/1938
Assignee:
HONEYWELL REGULATOR CO
Primary Class:
Other Classes:
236/75, 335/256, 335/267, 361/210
International Classes:
H01H51/04
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Description:

The present invention relates to improvements in electrically operated devices particularly electromagnets and control systems embodying improved forms of such devices. More specifically, the invention has to do with and has as its object the provision of electromagnets or relays which may be controlled by sensitive control instruments and which may require relatively heavy operating currents but do not necessitate that the operating current be carried by the instrument contacts. By reducing the amount of current which the instrument contacts must carry the instrument may be made smaller, more sensitive, and efficient and its life is greatly pro1 longed.

Another object is to reduce the power necessary for operation of electromagnets and the like and to reduce heating of such devices while in operation.

Another object is to provide electrical control apparatus whereby sensitive condition responsive instruments adapted for use with only small currents can satisfactorily and efficiently control relatively heavy equipment drawing heavy load currents.

Another object is the provision of an electromagnetic device having auxiliary contacts operated by an auxiliary armature, the auxiliary armature and contacts being controlled by a sensitive control instrument and the said auxiliary armature and contacts controlling energization of the electromagnetic device necessary for moving a main armature.

A detailed disclosure of representative forms of my invention may be found in the accompanying drawing and specification.

Figure 1 is a diagrammatic view of a system embodying my improved relay and including the electrical circuit wiring, Figure 2 is a detail view of the auxiliary contacting arrangement of Figure 1, Figure 3 is a view of the main part of Figure 1 with the parts in another position.

45 Figure 4 is another view of the structure of Figure 1 showing the parts in still another position, Figure 5 is similar to Figure 3 but showing the parts in a still further position, and Figure 6 is a sectional view of another embodiment of my invention.

Referring to Figure 1 of the drawing, numeral 10 designates generally a preferred form of my improved relay used in combination with a thermostat for controlling a compressor motor. The relay 10 comprises a generally U shaped core 11 of magnetic material positioned horizontally and a main armature 12 which is pivoted to the lower leg of the core II by means of a pivot pin 13. Wound on the upper leg of the core II are two separate coil windings 14 and 15, the coil 14 having relatively high resistance and coil 15 having relatively low resistance. Carried by the main armature 12 is a smaller auxiliary armature 16 which is attached to the main armature 12 by a flexible leaf or bracket 17 fastened to the main armature by a rivet or the like. The core I may be made of suitable conventional magnetic material of which cores are made and the armatures 16 and 12 may be made of soft iron or the like of which armatures are conventionally made. Adjacent the extremity of the upper leg of the core II is a pair of flexible contact carrying members 20 and 21 which may be suitably supported in any convenient manner (see Fig. 2). The members 20 and 21 are insulated from each other and they support electrical contacts 22 and 23, respectively. The auxiliary armature 16 carries a contact bar 24 supported by a carrying member or bracket 25 attached to the auxiliary armature. As will presently be explained in the description of operation following, the auxiliary armature 16 may be moved to an in position in contact with the extremity of the upper leg of the core 11 when one or both of the coils 14 and 15 are energized, and when the auxiliary armature 16 is in its in position the contact bar 24 is in a position bridging the electrical contacts 22 and 23. The main armature 12 carries at its upper end a contact actuating bracket 26 of right 3 angular configuration as seen on the drawing.

As will presently become apparent, the main armature 12 may also be moved in' a counter-clockwise direction into an in position by energization Sof the coils 14 and 15 and in this position of the parts as shown in Figure 4 the contact actuating bracket 26 engages with the flexible contact carrying members 20 and 21 and moves them out of engagement with the contact bar 24.

The main armature 12 has a contact carrying member 27 supported at its lower portion, the contact carrying member 27 having a contact 28 which moves into engagement with a fixed contact 29 when the main armature 12 is moved in a counter-clockwise direction into its in position.

The contact 29 is supported by a contact bracket or contact carrying member 30 which may be suitably supported in any convenient manner.

The contacts 28 and 29 form load contacts con- 65 trolling the energization and deenergization of the compressor motor shown at 31. The motor 31 has been illustrated as a compressor motor merely by way of example, it being apparent that the contacts 28 and 29 might control any other form of electrical load.

Numeral 35 indicates generally a bimetallic thermostat of conventional type comprising a bimetallic element 36 having attached thereto a switch blade 37 cooperating with a fixed electrical contact 38. Adjacent the blade 37 is a permanent magnet 39 which causes the blade 37 to engage with and disengage from the contact 38 with snap movements, the details of the thermostat forming no part of my invention.

In operation, when blade 37 of thermostat 35 engages contact 38 which it may do at a predetermined temperature for which the thermostat is set, a circuit is completed for energizing the coil 14 of relatively high resistance as follows: from wire 41 through thermostatic element 36, blade 37, fixed contact 38, wire 42, coil 14, wire 43, to wire 44, the wires 41 and 44 being connected to any suitable source of power (not shown). As pointed out above the coil 14 is of relatively high resistance and will permit only sufficient current to flow therethrough to create enough magnetomotive force to cause the auxiliary armature to be moved to the left to its in position as shown in Figure 3, the magnetic flux completing a magnetic circuit through the core 11, the auxiliary armature 16 and part of the main armature 12.

Figure 3 shows the structure with the parts in the position they assume the moment after the thermostat 35 energizes coil 14. It will be seen that in Figure 3 contact bar 24 is bridging contacts 22 and 23 and a-circuit is thereby completed energizing the coil 15 as follows: from wire 41 to wire 45, contact bracket 21, (see Figure 2) contact 23, contact bar 24, contact-22, contact bracket 20, wire 46, coil 15, wire 47, back to wire 44. Upon completion of this circuit the coil 15 is energized and as pointed out above this coil is of relatively low resistance and permits a flow of current therethrough sufficient to create a magnetomotive force somewhat greater than that created by energization of the coil 14. The magnetic flux produced by the coil 15 follows substantially the same magnetic circuit as the flux produced by the coil 14 and the combined magnetomotive forces produced by the two coils are sufficient to cause the main armature 12 to be rotated in a counter-clockwise direction thereby moving it to its in position as shown in Figure 4. With the main armature 12 in its in position as seen in Figure 4, the contact actuating bracket 26 engages the contact brackets 20 and 21 and move the contacts 22 and 23 out of engagement with the contact bar 24 in the manner described above in the structural description. As contact bar 24 no longer bridges contacts 22 and 23 the above described circuit therethrough energizing coil 15 is interrupted. Coil 15 being deenergized the total amount of magS5 netomotive force produced by the device is reduced to that created by the high resistance coil 14 which remains energized through the thermostat 35. The main armature 12 will remain at present in its position as shown in Figure 4, however, because the magnetomotive force produced by coil 14, while being relatively small, is sufficient to maintain armature 12 in its in position although it would not be sufficient to cause armature 12 to move about its pivot into in position. As soon as armature 12 reaches its in position, contacts 28 and 29 are brought together completing a circuit for energizing the compressor motor as follows: from wire 41 through wire 50, contact bracket 27, contact 28, contact 29, bracket 30, wire 51, motor 31, and wire 52 back to wire 44. From the foregoing, it will be seen that contacts 28 and 29 carry the load current for motor 3 which may be a relatively heavy current and which would be injurious to the contacts of thermostat 35 if it were permitted to flow through them. In my arrangement the load current is not even permitted to momentarily flow through the thermostatic contacts. The only current which the thermostatic contacts are required to carry is that relatively small current which the coil 14 draws.

The current which energizes coil 15 flows only momentarily through the contacts of Figure 2 thereby reducing the injurious effect of such current to a minimum and reducing to a minimum the total amount of power required for operation of the relay.

Figure 5 shows the structure with the parts in the position they are in at the instant that the thermostat 35 has separated its contacts and interrupted the circuit therethrough. Deenergization of coil 14 has released the main armature 12 and it has started to move in a clockwise direction so as to separate the contacts 28 and 29.

The advantages and utility of my invention as so far disclosed should be apparent from the foregoing. I employ a very small and sensitive thermostat for controlling a relatively great electrical load without subjecting the thermostatic contacts to heavy currents and without using more than a negligible amount of power for operation of the relay.

Figure 6 shows a second embodiment of my invention wherein I have employed its principles in an electrically actuated valve. Numeral 100 designates a valve body having the usual transverse partition 101 separating the inlet from the outlet of the valve, the partition 101 having a horizontal portion with an opening therein forming a valve port 102. The upper part of the valve body forms a flat cylindrical flange 103 the edges of which are screw-threaded and which is susceptible to the passage of magnetic flux therethrough. Numeral 104 designates an inverted cup-shaped casing or housing made of magnetic 60 material which engages in screw-threaded relation with the flange 103 and which encloses the operating mechanism of the valve. Numeral 105 designates a coil winding of relatively low resistance enclosed within the lower portion of member 104 and corresponding to the coil 15 of the previous embodiment. Numeral 106 designates a second coil winding of relatively high resistance housed within the upper part of member 104 and corresponding to the winding 14 of the previous embodiment. The coils 105 and 106 are separated by a flat iron ring 107 disposed between them and also by two rings 108 and 109 made of insulating material disposed on opposite sides of the ring 107. The windings 105 and 106 are substantially cylindrical and disposed within the interior of the coil 105 is an armature 110 made of magnetic material which also forms a valve stem, the lower end of which cooperates with the valve port 102 within the valve body 100.

The upper end of the armature 110 has a projecting finger III of materially smaller diameter extending upwardly therefrom and loosely encircling this projecting finger is an, iron ring. 112 forming an auxiliary armature corresponding to the auxiliary armature 16 of the previous embodiment. Numeral 113 designates a disc made of insulating material and carrying a pair of electrical contacts 114 and 115, the disc 113 being supported on supports 116 and 117 and biased into engagement with the said supports by a small coil spring 118. The contacts 114 and 115 are connected by wires as shown to a pair of terminals 119 and 120 extending exteriorly of the member 104. With the parts of Figure 6 in the position shown, the auxiliary armature 112 is below the magnetic center of the coil 106 and the main armature I 10 is below the magnetic center of the two coils 105 and 106.

The thermostat 135 of Figure 6 is identical with the thermostat 35 of the previous embodiment and whenever it closes bringing blade 137 into engagement with contact 138 a circuit is completed energizing the coil 106 as follows: from wire 141 to thermostat 135 through element 136, blade 137, contact 138, wire 142, coil 106, wire 143 back to wire 144. As soon as coil 106 is energized auxiliary armature 112 moves upwardly towards the center of magnetic attraction of coil 106 engaging with and bridging contacts 114 and 115, the magnetic flux circuit being through casing 104, ring 107 and the air gaps and armature within coil 106. The magnetomotive force of coil 106 is not of sufficient strength to cause auxiliary armature 112 to push disc 113 upwardly against the force of spring 118. Bridging of contacts 114 and 115 electrically connects the terminals 119 and 120 by reason of the wires which join the terminals 119 and 120 to the contacts 114 and 115, respectively. A circuit is thereby completed energizing coil 105 as follows: from wire 141 to thermostat 135, wire 145, terminals 119 and 120, wire 146, coil 105, and wire 147 back to wire 144. The magnetic flux produced by both the coils 105 and 106 combines in a single magnetic circuit through casing 104, flange 103, and the air gaps and armature within the coils having sufficient magnetomotive force to move the armature 110 upwardly so that projecting finger III engages the disc 113 forcing it upwardly against the bias of spring 118 moving the contacts 114 and 115 away from the auxiliary armature 112 and interrupting the circult of the coil 105. Upward movement of both the auxiliary armature and main armature is limited by the supports 116 and 117 with which the disc 113 is normally in engagement. At the time of deenergization of coil 105 when the armature 110 is in its upward position, its upper end extends into the magnetic field produced by the coil 106 and the magnetomotive force of this coil is sufficient to maintain the main armaSture I10 in its lifted position after it has been moved to that position by combined magnetomotive force of both coils. The lifted position of the armature 110 is shown in dotted lines in Figure 6, this position of course being open position of the valve. Whenever the thermostat 135 becomes satisfied, coil 106 is also deenergized and the armature 110 drops into closed position of the valve under the influence of gravity, the spring 118 again forcing the disc 113 into engagement with the supports 116 and I17.

From the foregoing those skilled in the art will appreciate that the embodiment of Figure 6 is similar to the previous embodiment in that it has corresponding elements and functions in a similar manner. The second embodiment also has the advantages and utilities pointed out in connection with the previous modification.

The disclosed embodiments of the invention are illustrative of various forms that the invention may take and of changes which may occur to those skilled in the art. The disclosure is to be interpreted in an illustrative rather than a limiting sense, the invention to be limited only in accordance with the appended claims.

I claim as my invention: 1. Electrical control apparatus for controlling relatively heavy load currents comprising in combination, electromagnetic means comprising, winding means, an auxiliary armature, and a main armature, means comprising load contacts for carrying a relatively heavy load actuable.by said main armature and auxiliary contacts actuable by said auxiliary armature, means comprising a sensitive thermostat having contacts adapted to handle only small currents, said last mentioned means comprising an electric circuit operable to energize said electromagnetic means sufficiently to produce a magnetomotive force great enough to operate said auxiliary armature whereby said auxiliary contacts become closed, closure of said auxiliary contacts completing an electrical circuit whereby said electromagnetic means is energized sufficiently to produce a magnetomotive force great enough to pull in said main armature whereby said load contacts are actuated, means associated with said main armature whereby upon pulling in of said main armature said last mentioned electrical circuit is interrupted, energization of said electromagnetic means by said means comprising a sensitive thermostat being sufficient to maintain said main armature in its in position after it has been moved to its in position.

2. Electrical control apparatus adapted to be responsive to relatively small controlling currents comprising in combination electromagnetic means capable of being energized so as to produce various electromagnetomotive forces, said means comprising winding means, a main armature, an auxiliary armature, and auxiliary contacts actuable by said auxiliary armature, means comprising an electric circuit for energizing said electromagnetic means for producing a magnetomotive force great enough to move said auxiliary armature whereby said auxiliary contacts are actuated, actuation of, said auxiliary contacts completing an electric circuit to said electromagnetic means whereby a magnetomotive force great enough to actuate said main armature into energized position is produced, means associated with said main armature for actuating said auxiliary contacts upon being moved into energized position whereby the energization of said electromagnetic means by said auxiliary contacts is terminated, energization of said electromagnetic CO means by said first mentioned energizing means being great enough to maintain said main armature in energized position after it has been moved into energized position.

3. In a device of the character described, in combination, a relay comprising a first winding, a second winding, a main armature, an auxiliary armature, and contacts actuable by said auxiliary armature, said auxiliary armature being relatively easily movable and said main armature requiring substantial force for moving it, said first winding being adapted upon energization thereof to produce a magnetomotive force great enough to move said auxiliary armature but not said main armature whereby said auxiliary contacts are actuated, actuation of said auxiliary contacts bringing about energization of said second winding, said second winding producing a magnetomotive force which acting with the magnetomotive force of. said first winding actuates said main armature, means adapted upon movement of said main armature to open the circuit through said auxiliary contacts so as to deenergize said second winding, said first winding producing sufficient magnetomotive force to maintain said main armature in the position into which it was moved under the influence of the magnetomotive force of both windings.

4. In apparatus of the character described in combination, electromagnetic means comprising winding means, an auxiliary armature, a main armature, and auxiliary contacts actuable by the armatures, said auxiliary armature being movable to an in position for closing the auxiliary contacts and said main armature being movable to an in position for opening the auxiliary contacts, means comprising primary contacts for energizing said winding means only sufficiently to move said auxiliary armature to its in position, said auxiliary armature requiring only a small current flow through said primary contacts for moving it to its in position, said auxiliary contacts closing upon movement of said auxiliary armature to its in position and completing an electrical circuit energizing said winding means sufficiently to move said main armature to its in position, said main armature requiring a relatively heavy current flow through said auxiliary contacts for moving it to its in position, said main armature having means for opening said auxiliary contacts upon movement to its in position for interrupting said electrical circuit and terminating the energization of said winding means brought about by said circuit, said auxiliary contacts having been only momentarily closed while said main armature was moving to its in position, and said primary contacts continuing energization of said winding means sufficiently to maintain said main armature in its in position whereby the relatively large current necessary for movement of said main armature never flows through said primary contacts and only momentarily through said auxiliary contacts.

5. In apparatus of the character described, in combination, electromagnetic means comprising winding means, an auxiliary armature, a main armature having load contacts actuable thereby and auxiliary contacting means actuable by said armatures, said contacting means comprising a movable contact member and a contact member actuable by said auxiliary armature, said auxiliary armature being movable to an in position for closing the contacting means and said main armature having means operative upon its being moved to its in position for moving said movable contact member away from said contact member actuable by said auxiliary armature and thereby opening said contacting means, means comprising "primary contacts for energizing said winding means only sufficiently to move said auxiliary armature to its in position, said auxiliary armature requiring only a small current flow through said primary contacts for moving it to its in position, said auxiliary contacting means closing upon movement of said auxiliary armature to its in position and completing an electrical circuit energizirig said winding means sufficiently to move said main armature to its in position, said main armature requiring a relatively heavy current flow through said auxiliary contacts for moving it to its in position, said auxiliary contacting means opening upon movement of said main armature to its in position for interrupting said electrical circuit and terminating the energization of said winding means brought about by said circuit, said auxiliary contacting means having been only momentarily closed while said main armature was moving to its in position, and said primary contacts continuing energization of said winding means sufficiently to maintain said main armature in its in position whereby the relatively large current necessary for movement of said main armature never flows through said primary contacts and only momentarily through said auxiliary contacts. 13 6. In apparatus of the character described, in combination, an electromagnetic device comprising winding means, a core member, a main armature pivoted thereto, and a smaller auxiliary armature movably attached to said main armature, contacting means actuable by said auxiliary armature, electrical means for energizing said winding means only sufficiently to move said auxiliary armature whereby said contacting means become closed, said main armature remaining unmoved, said contacting means completing a circuit increasing the magnetomotive force produced by said winding means, said main armature is moved, means whereby upon movement of said main armature said circuit is interrupted, energization of said winding means by said electrical means exerting sufficient influence upon said main armature to maintain it in the position to which it was moved.

7. In apparatus of the character described, in U combination, an electromagnetic device comprising a core member, a first winding, a second winding, a main armature pivoted to said core, a smaller auxiliary armature movably attached to said main armature, contacting means actuable by said auxiliary armature, electrical means for energizing said first winding, said first winding drawing a relatively small current and producing enough magnetic effect to move said auxiliary armature but not said main armature, movement 4S of said auxiliary armature actuating said contacting means whereby a circuit is completed energizing said second winding, energization of said second winding producing sufficient magnetic effect whereby said main armature is moved, means whereby movement of said main armature deenergizes said second winding, energization of said first winding being sufficient to maintain said main armature in the position to which it was moved. 6B 8. In a magnetic valve in combination, a first solenoid winding, a second solenoid winding, an armature movable within said windings, said first solenoid winding having relatively little magnetic strength and said second solenoid winding having relatively greater magnetic strength, electrical means for energizing said first solenoid winding, means actuated in response to energization of said first winding for energizing said second winding, the magnetomotive force of both ( windings combining to move said armature, means responsive to movement of said armature for deenergizing said second winding and said armature remaining in the position to which it was moved as long as said first winding remains energized.

9. In a magnetic valve, in combination, a first solenoid winding, a second solenoid winding, a main armature movable within said solenoid windings, an auxiliary armature movable upon energization of said first solenoid winding, said first winding drawing a relatively small current and said auxiliary armature requiring relatively small force for moving it, means actuable by said auxiliary armature whereby upon energization of said first winding said second winding is energized, said main armature moving in response to energization of both windings, means operable upon movement of said main armature for deenergizing said second winding, said first winding exerting sufficient influence upon said main armature to maintain it in the position to which it was moved under the influence of both windings.

10. In a magnetic valve, in combination, solenoid mechanism comprising an operating coil and a holding coil cooperating with a movable plunger, an armature movable in response to energization of said holding coil, contacting means actuable by said armature, means for energizing said holding coil whereby said armature actuates said contacting means completing a circuit energizing said operating coil, energization of said operating coil moving said plunger into the field of said holding coil, means actuated by said plunger for interrupting said circuit and deenergizing said operating coil upon movement of said plunger, said holding coil retaining said plunger in the position into which it was moved by said operating coil.

11. In a valve, in combination, a first electrical winding portion, a second electrical winding portion, an armature movable within said windings, said first winding portion having relatively little magnetic strength and said second winding portion having relatively greater magnetic strength, electrical means for energizing said first winding portion, means actuated in response to energization of said first winding portion for energizing said second winding portion, said armature moving under the influence of the magnetic effect produced when said second winding portion is energized, means responsive to movement of said armature for deenergizing said second winding portion and said armature remaining in the position to which it was moved, as long as said first winding portion remains energized.

12. In a valve, in combination, a winding means, an armature movable within said winding means, said winding means being capable of producing various degrees of magnetic effect, means for energizing said winding means, means comprising electrical contacts actuatable in response to energization of said winding means for completing an electrical circuit increasing the magnetic effect produced by said winding means, said armature being movable in response to said increased magnetic effect and operable to actuate said contacts to their original position, said armature remaining in the position to which it was moved. WILLIAM L. McGRATH.