US2817731A - Time delay control device - Google Patents

Description

Dec. 24, 1957 A. DE FALCO 2,317,731

TIME DELAY CONTROL DEVICE Filed Oct. 26, 1955 ANGELO DE FALCO IN V EN TOR.

By E an- United States Patent Ofiice 2,817,731 Patented Dec. 24, 1957 TIME DELAY CONTROL DEVICE Angelo De Falco, Irvington, N. J., assignor to Falcon Electronics Corp., Harrison, N. J., a corporation of New Jersey Application October 26, 1955, Serial No. 542,923

9 Claims. (Cl. 200-122) This invention relates generally to a control device in an electrical circuit and more particularly to a hermetically sealed thermally actuated time delay device or relay for use in an electrical circuit.

It has been exceedingly difiicult to develop small, substantially accurate hermetically sealed time delay devices or relays wherein the period of delay as is required between wide limits from /1. of a second to in excess of minutes.

This difficulty stems from the fact that the actuating element heretofore used, such as the well known bimetallic elements which are externally heated and which themselves control the period of time delay must be modified to secure the desired period of delay by either increasing the relative mass and surface area of the actuating element or reducing the energy input and modifying the insulation qualities of the actuating element.

Both of these means of varying the time delay present other difiiculties, such as reducing the relative motion between the contacts, which factor becomes more and more important as the size of the device or relay is reduced.

Since it is known that all materials have a specific coeflicient of expansion, that is, they tend to expand and contract at a particular rate for the material with variations in temperature, the present invention has utilized this physical characteristic of longitudinal expansion to .provide a thermally actuated time delay device for use in an electrical circuit which overcomes this problem.

Thus, the present invention covers a thermally actuated time delay device to overcome this problem which includes a thermally responsive primary actuating member adapted to expand and contract responsive to variations in current in the electrical circuit to which it is connected, and. a secondary control member of fixed length, each mounted at one respective end thereof, to a point of reference in said device in spaced relation to each other and joined at their other ends remote from the point of reference to each other; and an adjustable time delay setting means for exerting suflicient force on these coacting members to simultaneously place both members under compression and to place the secondary control member of fixed length under a predetermined tension whereby a switch element including an arm connected at one end to an intermediate point on said secondary control member and having a contact at the other end to coact with a stationary contact will be actuated on operationof the time delay device to open and close in accordance with the longitudinal expansion of the thermally responsive primary actuating member, forthe time delay corresponding to the predetermined tension setting of thesecondary control member.

In. addition to the time delay qualities, the present invention. is. highly resistant to shocks and in particular,

will withstand high frequency vibrations betweenS' and 500" cycles per second without producing resonant frequencies which might cause damage to the time delay device.

Accordingly, it is an object of the present invention to provide a thermally actuated time delay relay which is adapted to be reduced in physical dimensions without sacrificing accuracy of operations, and which will operate unaifected by frequencies from 5 to 500 cycles per second in temperature variation between -65 C. to C. and shocks up to 50 G.

It is a further object of the present invention to provide a simplified construction for a thermally actuated time delay device which enables the device to be manufactured in relatively small sizes.

Further objects and advantages of the invention will become evident from the following description with reference to the accompanying drawings in which:

Figure 1 is a vertical section showing the invention.

Figure 2 is an end view of the invention.

Figure 3 is a cross section taken on line 3-3 of Figure 1.

Figure 4 is a cross section through the actuating member taken on line 4-4.

Figure 5 is a top view of the upper header elements.

Figure 6 is a diagrammatic sketch showing the ole ments of the invention and their relationship.

Figure 7 is a partial vertical section showing a modified means for adjusting the tension of the control lever.

Referring more particularly to the drawings, Figures 1 and 2 show the time delay control device generally designated A having a header or support base 1 of a non-conducting or insulated material. The base 1- is provided with a plurality of circumferentially spaced contact prongs 2a, 2b,. 2c, 2d, 22, 2], and 2g, and has an annular flange? about the outer periphery for mounting a container 4 as by welding or any other suitable means to provide an air-tight joint. A cap or cover element 5 is provided at the upper end of the container or case 4 to hermetically seal the-container from-the atmosphere, the air in the container having been withdrawn prior to the sealing process in a manner well known in the present art and not more fully discussed herein as it does not form part of the present invention.

Mounted in the container is a primary or actuating member generally designated 6 and a secondary or control member 7.

The actuating member 6 includes a shell or expander element 8' which is fixedly'connected at oneend by means of a T-shaped bracket 9 to the prongs 2a and 2d in the base or header 1, as is clearly shown in Figures 1 and 3 of the drawings.

Figures 1 and 4 show that the expander element 8 houses or encloses in compact and closely sandwiched form a heater comprising the conventional mica element 10 with a coil of electric conducting wire 11 wound thereabout. Insulation elements 12 on opposite sides of the heater are of mica and transverse members 13 are filler material enclosed by expander element 8.

The electric conducting wire 11 is connected to the prongs 2b and 2c, respectively, which communicate with the circuit in which the relay is connected. The circuit delivers a variable current to the electric conducting wire 11 and thereby variesthe amount of heat delivered by the heatingelement to the expander element 8 of the actuating member 6.

The expander or shell 8,. the transverse elements 13 and the control member or arm will be of a material such, as stainless steel, or a like type alloy having a high coefficient of expansion. The relative massto surface area of the expander element or shell 6 being regulated by the added thickness of these elements 13 and the insulation therebetween in order to obtain the desired degree of expansion and contraction with varia tion in the heat developed by the current delivered to the coil of the wire in the heater.

The end of the expander element or shell 8 remote from the end fixed to a point of reference or base 1 is free to expand and contract relative to the base and is provided with a bracket 14 for connecting the free end of the expander element 8 of the actuating member 6 to the control member or arm 7. The other end of the control member or arm 7 is connected as by a strip or element 15 to the prongs 2 and 2g in the base 1, which as shown in Figures 1 and 2 are spaced a distance from the prongs 2a and 2d to which the corresponding end of the actuating member 6 is connected. The control arm and the actuating member thus form a triangle in side elevation, as is clearly shown in Figure l and the schematic diagram of Figure 6.

Figures 1 and 6 indicate that a spring element 16 is connected between the bracket connecting the free ends of elements 6 and 7 and a connecting button 17 mounted in an annular insulator 18 formed on the top header 19 disposed inwardly of the cover element for the container 4.

The control member or arm 7 has limited flexibility but has a predetermined fixed length which varies for the purpose of the present invention only with changes in temperature in the member itself. The ratio of the length of the control member or arm 7 to that of the expander element 8 plus the degree of flexibility of the control member 7 are important factors in determining the range of time delay settings for a particular relay as is more fully set forth hereinafter.

Adjusting means for setting tension and time delay period A threaded element 2t) mounted in a threaded boss 21 in the container element 4 may be adjusted from a point exterior of the container or the chamber formed by the container. This threaded element engages a glass bead 22 mounted on one end of a wire 23 which is welded or fixedly connected by any suitable means to the side of the control arm 7 remote from the actuating means.

Mounted to the side of the control member or arm 7 facing the actuating member 6 is a movable arm 24 having a contact 25 at the end remote from the point of connection to the control member 7. The movable contact 25 engages a stationary contact 26 which is fixediy connected to the prong 2e in the base member 1. Since the control arm is connected to the prongs 2 and 2g a circuit will be controlled whenever the movable contact 25 is brought into or out of engagement with the stationary contact 26, in accordance with the time delay periods set as hereinafter described.

By reason of the connecting relationships between the ends of the control member or arm 7 and the actuating member 6, when the threaded element 20 is threaded inwardly at its point of contact with the control member 7 the members 6 and 7 are moved from their equilibrium position relative the vertical or longitudinal Plane of the time delay control device to a position offset therefrom. In effect, the initial force is transmitted through the control member 7 to the actuating member 6 and as these members are offset they move into a compression state.

As the force exerted by the threaded element 20 is increased the members 6 and 7 continue to move into a higher state of compression until the limited flexibility of control member 7 causes it to bend thereby placing this member 7 under a combined state of compression and tension. The actuating member 6 at this point will have reached the maximum compression state that the control member 7 can transmit and by reason of the'fixed length of control member 7 as it bends the compression state of the actuating member 6 must reduce.

By adjusting or setting the tension or bend of control member 7 while both members 6 and 7 are under a compression state the desired time delay can be cstablished. Dining operation of the time delay control device heating the actuating member 6 will cause it to expand longitudinally. However, it is connected to the free end of member 7 and since member 7 has a fixed length, the actuating member 6 will further reduce its state of compression and in turn increase the tension or how of control member 7. This increased tension or bowing of control member 7 is conveyed through the movable arm 24 which amplifies the signal of the actuating member, thus moving the contact 25 on the movable arm into engagement with the stationary contact 26.

The degree of movement of member 6 and the tension on the control member or arm '7 can be translated into terms of a time delay that is the period that the mo.- able contacts will be held in or out of contact with each other depending on the desired conditions of operation. By adjusting the threaded member inwardly the time delay period may be reduced to as little as A of a second and, conversely, when moved outwardly within the limits of the adjustment, depending on the mass surface relationship of the actuating member 6, it will lengthen the period of time delay to a period in excess of five minutes.

Operation In operation, when current is delivered from 'the circuit through the prongs 2b and 2c the resistance in the electric coil 11 will vary the heat delivered by the heater in accordance with variations in the circuit to which the time delay control device is connected.

The actuating element 6 will as a result vary its length in accordance with the variation in heat received from the heater.

Since the length of the control member 7 is fixed except for its variation in length due to the temperature changes of the element itself, it will move the actuating member 6 from the vertical position and bow in a direction towards the actuating member thereby actuating the system which is controlled by these switch elements. As long as the heat delivered holds the actuating element to the length which maintains the control arm in the bowed position for closing the respective contacts 25 and 26, the relay or control device will continue to actuate the system to which it is connected. However, as it cools, the expander element 8 thereof shortens and the circuit will be broken by the separation of the contacts 25 and 26 as the movable arm carrying the contact 25 amplifies the signal indicating the reduction of the bow of the member 7. The action is of course ready to repeat itself once again whenever current is delivered to the coil for the heater element to heat the actuating element 6 as has been above described.

It is believed obvious that while a make type circuit is shown in the present disclosure that the circuit could also be a break type circuit, that is, the movement of the movable arm would open the switch contacts 25 and 26 instead of closing them and that this would not constitute a departure from the present invention but is a mere matter of design which is well known in the art.

Figure 7 shows a modified form of the means for adjusting the tension in the control member 7. The control device is otherwise identical with that above described for the form of the invention shown in Figure 1.

Thus, Figure 7 shows that this modified form of the adjusting means comprises a V-shaped lever 30 pivotally connected as at 31 to the upper header 19. An air-tight resilient bellows element 32 tends to pivot the lever 30 out of contact with the glass head 22.

Threadably mounted in the header element 19 and extending into the bellows element is an adjusting screw 33 which is in engagement at one end with the upper end of the lever 30 a spaced distance from the point on which the lever pivots and at its other end extends to a point exterior-of device A as through the opening 34 provided in the cover elementS.

By threadingthe adjusting screw 33 inwardly, tension on member 7 will be increased and the period of time delay accordingly reduced and, conversely, threading the adjusting screw 33 outwardly will reduce the tension on member 7 thereby increasing the period of time delay.

It will be understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that they may be widely modified within the invention defined by the claims.

What is claimed is:

1. In a hermetically sealed time delay control device to be connected in a current carrying circuit, a thermally responsive actuating member having one end connected to a point of reference in said control device and communicating with said circuit to allow the free end of said member to expand longitudinally relative to said point of reference in response to thermal changes caused by variations in the current in said circuit, an integral control member connected to said point of reference a spaced distance from said actuating member and directly to the free end of said actuating member, adjustable means to engage said control member at a point intermediate the point of reference and point of connection with said actuating member for exerting simultaneously sufiicient force to move said actuating member and said control member into a compression state and to place said control member under a predetermined tension to regulate the time delay of said control device, and means in operable relation with said control member including a switch to be opened and closed in response to signals from said actuating member.

2. In a hermetically sealed time delay control device, a support base, an actuating member connected at one end to said support base and free to expand and contract at the end remote from the connected end, a control member of predetermined fixed length connected at one end to said support base a spaced distance from the connected end of said actuating member and at the other end to the free end of said actuating member, time delay setting means in engagement with said actuating member at a point intermediate the point of reference and the point of connection of said actuating member and said control member to each other to normally bias said members a predetermined distance in one direction to simultaneously move said actuating member and control member into a compression state and to place said control member under a predetermined tension for the desired period of time delay, an electrical element in said actuating member connected to said current to cause said actuating member to elongate and contract longitudinally in response to current variation in said circuit whereby said control member will be moved accordingly, and means forming a switch having its movable element operatively connected to said control member, and a stationary element, said movable element to be opened and closed on movement of said control member in response to signals from said actuating member.

3. In a hermetically sealed time delay control device to be connected in a current carrying circuit, a support base, a thermally responsive actuating member having one end connected to said support base and the other end free to expand longitudinally relative to said support base, an electric heater on said thermally responsive actuating member connected in said circuit and adapted to deliver heat to said thermally responsive member in accordance with variations in current in said circuit, a control member having a fixed length and connected at one end to said support base a spaced distance from said actuating member and at the other end to the free end of the actuating member, adjustable means on said device in engagement with said control member at a point intermediate the point of reference and the point of connection to said actuating member to move said control member and the actuating member into a compression state and simultaneously to exert a predetermined tension on said control member for the desired time delay period, a switch including a stationary contact and a movable arm having a contact at the end thereof to coact with said stationary contact, said movable arm having the end remote from the contact thereon connected to said control member intermediate the point of engagement with said adjustable means and the point of connection to said actuating member, said movable arm adapted to move said contact into and out of engagement with said stationary contact on signals from said actuating member delivered through the control member.

4. In a hermetically sealed time delay control device to be connected in a current carrying circuit, a support base, a thermally responsive actuating member having one end connected to said support base and the other end free to expand longitudinally relative to said support base, an electric heater in said thermally responsive actuating member connectedin said circuit and adapted to deliver heat to said thermally responsive member in accordance with variations in current in said circuit, a control member having a fixed length and connected at one end to said support base a spaced distance from said actuating member and at the other end directly to the free end of the actuating member, adjustable means to engage said control member at a point intermediate the point of reference and the point of connection to said actuating member to exert sufiicient force to simultaneously place said actuating member and said control member under compression and said control member under tension, said adjustable means adjustable from the exterior of the device, a switch having a stationary contact and a movable contact, said movable contact connected to said control member and to be moved into and out of engagement with said stationary contact in response to signals from said control member on thermal actuation of said actuating member.

5. In a hermetically sealed time delay control device as claimed in claim 4 including an arm having one end connected intermediate the point said adjustable member contacts said control member and its point of connection to the free end of said actuating member, and said movable contact disposed on said movable arm at the end remote from said connected end.

6. In the combination as claimed in claim 3 wherein said device includes an upper header, and resilient means disposed between the upper header and the point of common connection between said control lever and said actuating member to prevent undue shock to said members during operation.

7. In the combination as claimed in claim 3 wherein said actuating member is relatively stiff and is composed of materials having a relatively high coefiicient of expansion, and said control member has limited flexibility and made of a material having substantially the same coeflicient of expansion as said actuating member.

8. In the combination as claimed in claim 3 wherein said control device includes an upper header therein, and said adjusting means includes an airtight bellows in said upper header, a movable member disposed to extend through said airtight bellows, a glass bead medially spaced on said control member, said movable arm to operatively engage said glass bead at a point remote from the end extending through said bellows for moving said control member and actuating member into the desired time delay period setting position.

9. In a hermetically sealed time delay control device to be connected in a current carrying circuit, a support base, a casing mounted in airtight engagement on said support base, a thermally responsive actuating member connected at one end to said support base and free to expand longitudinally relative to said base, an electric heater on said thermally responsive actuating member connected in said circuit and adapted to deliver heat to said thermally responsive member in accordance with variations in current in said circuit, a control member of fired length connected at one end to said support base a spaced distance from said actuating member and at the other end to the free end of the actuating member and to form a substantially triangular configuration there- With in side view, adjustable means mounted in said casing adapted to be adjusted from the exterior of said device to bring it into engagement With said control memw her at a point intermediate the point of reference and the point of connection to said actuating member, said adjustable means normally biasing simultaneously in a single direction the control member and the actuating member to exert compression on both said control member and said actuating member and predetermined tension on said control member alone, a movable arm connected at one end to said control member between said intermediate point of contact and the point of connection to said ac tuating member on the face thereof nearest the actuating member, a contact on the end of said movable arm remote from said point of connection to the control memher, a. stationary contact on said supporting base, and an electrical heater in said actuating member to cause said actuating member to elongate longitudinally in response to variations in current in said circuit, said movable arm and said control member so constructed and arranged that elongation of said actuating member will cause said movable arm to move into and out of engagement with said stationary contact.

Referen-ees Cited in the file of this patent UNITED STATES PATENTS 1,118,608 Wilkinson Nov. 24, 1914 2,154,042 Gough Apr. 11, 1939 2,576,976 Stagner Dec. 4, 1951 2,700,084 Broekhuysen Jan. 18, 1955 2,735,912 Ulanet Feb. 21, 1956 FOREIGN PATENTS 21,540 Great Britain Sept. 21, 1912 688,264 Great Britain Mar. 4, 1953

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