US1931774A - Contactor - Google Patents

Description

CONTACTOR Filed April 24, 1931 i I /4 5 5 24 1 5 g \Q i L---6 I INVENTOR.

' MR. MOI [Raffl- BY 64w. d (51 #65 A TTORNE Y Patented Oct. 24, 1933 CONTACTOR John R. Skoverski, Berkeley, Calif., assignor of one-half to George H. Roberts and one-half to Joseph Schor, both of San Francisco, Calif.

Application April 24, 1931. Serial No. 532,399

3 Claims.

My invention relates to a contactor, and particularly to a quick-acting contactor for use in conjunction with a circuit control such as a thermostat.

It is among the objects of my invention to provide a contactor which is sensitive to relatively small movements in a control element.

Further objects of my invention include the provision of a contactor which, when used in conjunction with a circuit control such as a thermostat, will give close regulation, and which will maintain a constant set of conditions, such as keeping a heating element at a selected and substantially constant temperature.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following descrip tion of my invention. It is to be understood that I do not limit myself to this disclosure of species of my invention, as I may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawing:

Figure 1 is a side elevational view showing the contactor embodyingmy invention in conjunction with a thermostat; portions of the control element being broken away to shorten the view and disclose the construction more clearly.

Figure 2 is a top view of the contactor showing the contact elements in closed position; and Figure 3 is a similar view showing the contact elements in open position. v,

Figure 4 is a detail vertical sectional view taken in a plane indicated by the line 44v of Figure 2.

In terms of broad inclusion, the contactor embodying my invention comprises a movable element having two positions of rest. The element is preferably secured to a pivotally mounted arm, and a fixed element is provided adjacent the arm, so that in one position of rest the movable element is engaged with the fixed element and in the other position of rest it is disengagedfrom the fixed element. A stressed spring, preferably a spring under tension, is provided, and is secured at one end to the arm; the spring being arranged to extend toward the arm pivot.

Means are provided for moving the free end of the spring past the arm pivot to snap the movable element from one position to the other. In the preferred form of my invention a pivotally mounted lever is provided and the stressed spring is connected between the arm and the element 19 is a strip 22 of thin flexible metal lever, and means are provided for actuating the lever to move the lever connected end of the spring. The actuating means is preferably an arm adapted to move into engagement with the lever, and may conveniently comprise an arm mounted for movement with a control element, such as the bi-metallic strip of a thermostat.

In greater detail, the contactor embodying my invention comprises a suitable base 2 upon which the various parts of the mechanism are mounted. For the purposes of illustration the contactor is shown and described as embodied in a thermostat; it being understood however that the contactor, maybe used in other devices and in conjunction with other control means. The base 2 is preferably in the nature of a plate or disk, and is provided adjacent its central portions with an aperture about the lower end of which is formeda boss 3. The boss provides a seat for the upper end of a depending helix 4 comprising a strip of suitable bi-metallic material. A rod 6 is provided to extend thru the helix 4 and the base plate aperture, and preferably projects for a short distance above the base 2. The lower end of the rod is. inserted in a collar 7 seated in the depending end of the helix 4. A screw 8 serves to secure the helix, collar and rod together. The upper' or projecting end of the rod 6 is provided with a radially extending arm 9 carrying at its outer end an upwardly projecting pin 11. A screw 10 serves to clamp the arm 9 to the rod 6, and allows the arm to be set at-a selected position in the normal condition of the'helix 4. .By this arrangement it is apparent that the arm 9 will move about the base 2 as the bi-metallic strip in the helix-4 expands and contracts due to varying conditions of temperature; this movement being clockwise, as viewed in Figures 2 and 3, whenthe strip expands under increasing temperature.

.Mounted on the base 2 is a bracket 12 to which is secured a fixed contactelement 13. The bracket 12 is suitably insulated from the base and is held fixed by the screws 14. A terminal screw .16 threaded in the bracket 12 provides means for securing a lead wire to complete the connection to the fixed element 13. A bracket arm 17, preferably in the nature of a bell crank, is pivotally mounted on the base '2 on a suitable pivot pin 18. Secured to one end of the arm 17 and insulated therefrom is a second contact element '19 adapted to engage with the fixed element .13.

Held bythe nut 21 which serves to secure the suitably insulated from the arm 17. The strip 22 is bent in a U-shape, and is secured at its outer end to a suitable bracket 23 by a screw 24; this screw also serving as a terminal for connecting a lead wire. The bracket 23 is suitably insulated from the base 2, and is held in position by the screws 26. One of the screws 26 is provided with a notch. 27 to make room for the nut 21 in tho outward movement of the arm 17; the screw serving as a stop to limit the arm movement.

It is thus seen that the movable contact element 19 has two positions of rest; in one position the movable element being in engagement with the fixed element 13, and in the other position of rest the movable element being disengaged from the fixed element. The flexible strip 22 completes the connection from the terminal screw 24 to the movable or pivotally mounted contact element 19, and at the same time permits movement of the element about the arm pivot 18.

Arranged above the base 2 and therefrom by a mice 01 tubular standards 28 is a plate 29 secured to the base by the screws 31. A lever 32 is provided and is arranged on the plate 29 to overlie a portion or the arm 17. The lever 32 is pivotally mounted on the base 2 by a pin 33 iournaled in the plate 29 and the base; a collar 34 being provided to hold the pin 33 in position. One end of the lever 32 is provided with an upwardly projecting pin 36, preferably positioned adiacently above the arm pin 18, and the lever is provided with an aperture or slot 3'1 arranged between the lever pin 36 and the lever pivot D111 33.

The plate 29 is also provided with an aperture or slot 38 positioned immediately below and slimmed with the lever aperture 37. A pin 39 is mounted on the end of arm 17 and is arranged to proiect upwardly thru the apertures 3'7 and 38. The upper ends or the pins 36 and 39 are conheated by a stressedtension spring 41. Refer- 'l l particularly to Figures 2 and 3, it will be observed that the spring 41 extends from the arm pin 39 toward the arm pivot 18, and that in one position or the movable element 19 the lever connected end of the spring is positioned at one 88100! the arm pivot, and that in the other position of theelernent the end 01' the spring is positioned at the other side of the pivot. In both of the positions assumed by the lever 32, the spring 41, in maintaining the shortest distance between the pins36 and 39, holds the lever with its aperture 87 centered about the pin 39.

By actuating lever 32 so that the lever connected and o! the spring 41 is moved past the arm pivot 18 the arm 17 is moved to snap the movable element 19 from one position to the other. The quick action or the contactor is due to the actionofthe spring 41. As the lever connected end or the spring moves toward the arm pivot 18 no movement of the arm 17 results, but as soon as the end of the spring passes over center, viz., over the axis of the pivot pin 18, the arm 17 instantaneously shifts over to snap the movable elet'nent from one position of rest to the other. In other words, the contact elements 13 and 19 are opened and closed with movements of exceedingly quick action.

While I have shown the contactor or my invention as embodied in a specific mechanism, it in to be noted that broadly the contactor comprises a movable or pivoted element having two positions 0! rest, and a stressed spring having one and connected with the element and extending toward the pivot to optionally hold the element in one or the other of the positions of rest, together with means for moving the free end of the spring past the pivot to snap the element from one position to the other. Another important feature of the invention resides in the fact that the contact elements may be snapped into or out of enagement by relatively small movements at the free end of the spring; it being necessary to only move the free end suificiently to pass center. By reason of this action the contactor is sensitive of relatively small movements in a control element, and when used in connection with delicate controls may be adjusted to give extremely close regulation.

As best illustrated in Figures 2 and 3, the end of the lever 32, opposite the pin 36, is formed to provide means for receiving the pin 11 of the helix arm 9; the lever arm from the pivot pin 33 being shorter at this end to increase the mechanical advantage so that a small movement at the actuating end of the lever will impart a considerably magnified movement to the end of the lever carrying the spring holding pin 36. This construction still further increases the sensitiveness of the instrument.

Preferably, the actuating end of the lever 32 is provided with a cam edge 42 having a depression 43 forming the stops 44 and 46. In the normal position of the lever 32, viz., that position in which the contact elements are engaged as shown in Figure 2, the helix arm 9 may advance, due to the expansion of the helix strip under the influence of heat, until its pin 11 moves up against the lever stop 44. Further advance of the helix arm now moves the lever 32 to effect disengagement of the contact elements l3 and 19. Since the thermostat is prelerably used in conjunction with a heating circuit, the temperature of which is to be controlled, the contactor is hooked up with the circuit so that separation of the contact element will open the circuit.

In such a control the bi-metallic strip is, of course, arranged to come under the influence of the heat caused by the heating units in the circuit. After opening the circuit the temperature falls and the bi-metallic strip commences to contract, thereby causing the helix arm 9 to rotate back toward its normal position. At the beginning of this recovery movement, however, the arm pin 11 is positioned against the lever stop 46, and the backward movement of the helix arm immediately causes the lever 32 to be actuated to move the spring holding pin 36 back across the arm pivot 18. This action snaps the movable element 19 back into engagement with the fixed element 13 to again close the circuit. Meanwhile the helix arm 9 continues to recede; the pin 11 riding out over the cam edge 42.

As the heat in the circuit increases again the action is repeated so that a temperature control is eflected. In the present device the temperature is controlled within very narrow limits to maintain a substantially constant value. In reiteration, it is pointed out that this close regulation follows directly from the fact that a quick acting contactor is provided which is sensitive to relatively small movements in a control element.

I claim:

1. A thermostat comprising a base, an element fixed on the base, an arm pivotally mounted on the base, an element on the arm adapted to engage with said fixed element, a lever pivotally mounted on the base, a stressed spring connected between the arm and lever for optionally holding the arm element in engagement with the fixed element or in a position of disengagement therefrom, a helix of bi-metallic strip having one end secured to the base, an arm connected for movement with the other end of the helix, said helix arm being positioned to move into and out of engagement with the lever said engaging and disengaging movements of the helix arm operating to move the lever connected end of the spring to snap the arm element from one position to the other.

2. A thermostat comprising a base, an element fixed on the base, an arm pivotally mounted on the base, an element on the arm adapted to engage with said fixed element, a lever pivotally mounted on the base, a stressed spring connected between the arm and lever for optionally holding the arm element in engagement with the fixed element or in a position of disengagement therefrom, a helix of bi-metallic strip having one end secured to the base, and an actuating arm connected for rotation with the other end of the helix and having a normal position of rest spaced from said lever, the actuating arm being adapted for rotation into and out of engagement with the lever, said engaging and disengaging movements of the actuating arm operating to move the lever connected end of the spring to snap the arm element from one position to the other.

3. A thermostat comprising a base, an element fixed on the base, an arm pivotally mounted on the base, an element on the arm adapted to engage with said fixed element, a lever pivotally mounted on the base, a stressed spring connected between the arm and lever for optionally holding the arm element in engagement with the fixed element or in a position of disengagement therefrom, a helix of bi-metallic strip having one end secured to the base, an actuating arm connected for rotation with the other end of the helix and having a normal position of rest spaced from said lever, the actuating arm being adapted for rotation into and out of engagement with the lever, said'engaging and disengaging movements of the actuating arm operating to move the lever connected end of the spring to snap the arm element from one position to the other, and adjustable mounting means for the actuating arm so that said spacing between the lever and the actuating arm in its normal position of rest may be selectively varied.

JOHN R. SKOVERSKI.

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