US3222487A - Dual purpose electrical contact element - Google Patents

Description

Dec. 7, 1965 w. F. JUPTNER DUAL PURPOSE ELECTRICAL CONTACT ELEMENT Filed May 29, 1963 FIGI INVENTOR.

F.' JUPTNER WILLIAM ATTORNEY United States Patent 3,222,487 DUAL PURPOSE ELECTRICAL CONTACT ELEMENT William F. .luptner, Laguna Beach, Calif, assignor to Babcock Electronics Corporation, Costa Mesa, Califi, a

corporation of California Filed May 29, 1963, Ser. No. 284,066 5 Claims. (Cl. 200166) This invention relates generally to electrical contacts, and more particularly to electrical contacts for controlling different amounts of electrical energy.

As is well known in the art, electrical contacts for controlling the flow of electrical current must be particularized to the amount of current to be controlled. That is, although electrical energy consists of the flow of electrons along a given path, the number of electrons which flow past a given point during a given unit of time may vary considerably. The electrical potential or voltage of the source of power causing the flow of electrons may be substantially any value, and the current or rate of electron flow will vary accordingly. As such, the greater the voltage of the source, the higher the current for a given set of circuit parameters.

The characteristics of a given electrical circuit also may vary considerably. That is, the resistance, inductance and capacitance of a circuit may be Within relatively wide ranges of values. The greater the resistance to the flow of electrons in the circuit, the smaller will be the current. Thus, the current in a given circuit varies inversely with the resistance of such circuit to the flow of electrons.

It has been discovered that an entirely different style or type of electrical contact is required for effectively controlling a small amount of current as compared to contacts necessary for controlling large or heavy current. The distinction is founded principally on the fact that in controlling a large current considerable energy is available for overcoming the many obstacles or practical limitations to efiiciently operate a pair of contacts. Conversely, where only a small amount of current is to be controlled, insufiicient electrical energy is available so that external energy must be supplied to overcome such obstacles.

Electrical contacts are very vulnerable to the accumulation of foreign materials including moisture and films of various kinds which are the result of atmospheric conditions. Where large current is available, such foreign material and films are burned away by the current to thereby provide good electrical conductivity between the pair of cooperating contacts. However, where only a minimum amount of current is to be controlled, such foreign material and films create such a high resistance to the flow of electrons that the extremely weak current is virtually stopped.

Heretofore, separate pairs of contacts frequently have been used interchangeably in a given switch or relay in accordance with the amount of current to be controlled. This, of course, has been inconvenient, and time-consuming particularly where a given switch or relay has many different applications. Also, in mass-producing such devices, it is desirable to construct them with a given set of contacts which can be used for controlling any amount of current to be encountered.

It is an object of the present invention to provide an electrical contact which is operable for efficiently con trolling widely differing amounts of electrical current.

Another object of the present invention is to provide an electrical contact having a plurality of contact surfaces, the proper one of which is substantially automatically selected in accordance with the amount of current to be controlled.

3,222,487 Patented Dec. 7, 1965 Another object of the present invention is to provide a multipurpose electrical contact having both a relatively large contact surface and a relatively small contact surface, the former of which is useable for controlling high current flow while the latter is useable for controlling small current flow.

A further object of the present invention is to provide an electrical contact as characterized above wherein the relatively small contact surface is automatically eliminated when large current is to be controlled.

A still further object of the present invention is to provide an electrical contact as characterized above wherein the relatively small contact surface is eroded away by controlling the large current flow so as to expose the relatively large contact surface.

A further object of the present invention is to provide a pair of electrical contacts of the multipurpose type having several different sets of cooperating contact surfaces.

A further object of the present invention is to provide electrical contacts as characterized above which are simple and inexpensive to manufacture, and which are rugged and dependable in operation.

The novel features which I consider characteristic of my invention are set forth with particularity in the appended claims. The device itself, however, both as to its organization and mode of operation, together with additional objects and advantages thereof, will best be understodd from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of an electrical contact according to the present invention;

FIGURE 2 is an end elevational view taken substantially along line 2-2 of FIGURE 1;

FIGURE 3 is a fragmentary side elevational view of a portion of the contact of FIGURE 1;

FIGURE 4 is a side elevational view of a pair of cooperating electrical contacts according to the present invention;

FIGURE 5 is a side elevational view similar to FIG- URE 4, showing the contacts in operating position; and

FIGURE 6 is an enlarged fragmentary sectional view of the cooperating contacts of FIGURE 5.

Like reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to FIGURE 1 of the drawings, the embodi-' ment 8 chosen for illustration of the present invention comprises a generally U-shaped elongated body portion 10 formed of resilient material which is a good conductor of electrical energy. One end 10a thereof is reversely bent to provide mounting means in the form of a loop 12 to be positioned on a terminal post or the like as will hereinafter be explained.

The other end 1011 of body portion 10 is formed with an offset portion 14 having a relatively large flat contact surface 14a. The offset nature of portion 14 removes surface 14a from the plane of end portion 10b as shown in FIGURES l, 4 and 5 of the drawings. This, as will hereinafter become more apparent, clearly defines the size and shape of the contact surface 141:.

As shown most clearly in FIGURE 2 of the drawings, the body portion 10 is of substantially constant width from the end portion 10a thereof through the relatively large contact surface 14a- Imrnediately adjacent the contact surface 14a, or positioned on such surface if desired, is a relatively small contact surface 16 afforded by a tapered member 18. In the embodiment chosen for illustration of the present invention, the tapered member 18 is the extreme end of the body portion 10. However, as will hereinafter become more apparent, such member 18 may be provided in a different position relative to'the large contact surface 14a.

The tapered member 18 extends beyond the plane of the contact surface 14a, the apex of such tapered member lying in a plane which is substantially parallel to the plane of surface 14a. As will be readily apparent to those persons skilled in the art, the small contact surface 16 may be formed of one or more comically-shaped extensions if desired.

The end portion 10b of body portion 10 is tapered as at 20 and 22 so that the tapered member 18 is considerably smaller in width than the main portion of body portion 10. As such, the small contact surface 16 is of limited length, such arrangement further reducing the'size of such surface.

Asshown most clearly in'FIGURE 1 of the drawings, the tapered member 18 may be provided by upsetting the extreme end of the end portion 10b. That is, as will be readily apparent to those persons skilled in the art, the entire contact element may be formed in a forming press. The forming die used in such press may include means for causing the'end of end portion 10b to be upset as shown in FIGURES 1 and 2' to provide'the tapered member 18.

As shown most clearly in FIGURES 4 and 5, the mounting-loop 12 is positioned about a mounting post 22, the latter of which is a terminal member having good electrical conductivity. The loop 12 provides a relatively firm mechanical connection between the contact element and the mounting post' 22. To assist such mechanical connection and to provide good electrical conductivity therebetween, a bead of solder 24 is provided within the V-shaped opening between loop 12 and post 22. Such solder may be poured into the opening so as to electrically bond the variouselements together.

For cooperation with contact element 10 there is provided, as shown in FIGURES 4, 5 and 6, a contact member 26 which may take substantially any desired form and shape. As shown therein, member 26 has a flat contact surface-26a for engagement with both the small contact surface 16 and the large contact surface 14a of contact element 8;

As will be readily apparent to those persons skilled in' the art,:the contact member 26 is mounted for movement into and out of engagement with contact element 8. In the alternative, contact member 26 may be stationary and the mounting post 22 movable with respect thereto for movement of contact element 8 in to engagement with contact surface 26a. The arrangement shown in the drawings is for illustration of the present invention and contemplates that the mounting post 22 is stationary and that the contact member 26 is movable with respect thereto.

As mentioned above, the foreign materials, including moisture and other films, which accumulate on the contact surfaces as a result of the atmosphere, are easily eliminated when high current electrical energy is being controlled. Such high current energy quickly traverses the gap created between the'contacts by the foreign material. Such arcing produces considerable heat energy which quickly burns away the foreign material and films to provide two clean contact surfaces on the contact element and member.

When an extremely small amount of electrical current is being controlled, insuificient energy is available from the current itself to cause arcing between the contact surfaces. If such arcing should take place, the small current is insufficient to provide heat for burning away the foreign material.

Due to this shortcoming, the film and foreign material must be overcome by external forces. To accomplish this with the small inherent biasing force of the resilient body portion 10 of contact element 8, the area of engagement between the contact element 8 and the contact member 26 must be extremely small. The reduced area causes the force of the bias to create a relatively high pressure between the contact element and the contact member.

Such relatively high pressure is then utilized to physically break through the foreign material and films so as to permit the contact surfaces to be in firm engagement.

Due to the tapered construction of member 18 of the contact element 8, the contact surface 16 is virtually a single line. That is, due to the fact that the contact surface 26a of contact member 26 is relatively fiat surface, the contact surface 16 which extends beyond the large contact surface 14a engages the surface 26a along. a single line. As will be readily apparent to those persons skilled in the art, this configuration provides a very small area of contact between the contact element 8 and the contact member 26. The fact that the tapered member 18 is of reduced width as compared to the width of body portion 10, the length of the line of contact is reduced accordingly.

As a result of the'iaforedesonibed construction, the inherent biasing force of contact element 8 is sufficient to cause the tapered member 18 to be forced through the foreign material and films interposed between the contact member 26 and contact element 8. This results in a low resistance electrical circuit between contact member 26 and mounting post 22 so that a small or weak current can be effectively controlled. The contact member 26 is permitted to be moved between circuit-making and circuit-breaking positions relative to contact element 8 for control of such low current electrical energy.

In the event the aforedescribeld contact arrangement is used to control relatively high current, it is not necessary for an operator to make any installation changes. Rather, the contact element 8 is automatically converted from a low current contact to a high current contact. This occurs in substantially the following manner.

With the relatively small contact surface 16 making good electrical contact with contact surface 260 of member 26, current is caused to flow between the element 8 and member 26. If such current is relatively high, the small area of contact between the contact surfaces offers a relatively high resistance. Upon opening and closing of the contacts, the large current produces arcing which generates a considerable amount of heat. Due to the tapered configuration of member 18, the apex thereof is most vulnerable to attack by such heat. As a result, the high heat energy quickly erodes away the extended portion of the tapered member 18, as shown most clearly in FIGURE 6 of the drawings.

When this occurs, the flat contact surface 26a of contact member 26 engages the relatively large contact surface 14a of contact element 8. Such transition from low current use to high current use is indicated with broken lines in FIGURE 4. The inherent bias of resilient body portion 10 continues to urge the large contact surface 14a into engagement with surface 26a of contact member 26.

The foreign material between the large contact surface 14a and contact surface 26w are quickly burned away by the relatively large amount of electrical energy available. Initially, such foreign material prevents the surfaces 14a and 26a from coming into firm engagement. As a result, the electrical resistance between such surfaces is relatively high. The large current flow, however, traverses such high resistance thereby producing considerable heat energy which quickly burns away the foreign material. Thus, the contact surfaces 14a and 26a are permitted to move into firm engagement under the influence of the biasing force of contact element 8. Thereafter, the contact member 26 may be moved between its circuit-making and circuit-breaking position relative to contact element 8 for control of the relatively high or strong current.

It is contemplated within the scope of the present invention that external biasing means may be employed in place of the inherent biasing force of the U-shaped contact element 8. In any event, however, the biasing force urging the various contact surfaces to engagement may be constant for control of either the low or high current electrical energy.

It is thus seen that the present invention provides a multipurpose electrical contact for controlling both low and high current electrical energy. Further such contact is operable to substantially automatically convert itself from condition for controlling low current energy to condition for controlling high current energy.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim:

1. A dual purpose electrical contact element for use in efiiciently making and breaking either high or low current electrical energy comprising in combination, a contactor, a relatively large contact on said contactor for engagement with an electrically conductive member to efiiciently conduct therebetween electrical energy of predetermined high current, and a relatively small contact on said contactor offset from said large contact to normally engage said member and thereby prevent engagement of said member by said relatively large contact, said small contact being sufliciently smaller than said large contact to be consumed by heat upon conduction therethrough of said predetermined high current energy, whereby said small contact is operable to conduct low current energy and said large contact is operable to conduct high current energy with said member.

2. A dual purpose electrical contact element for use in efliciently making and breaking either high or low current electrical energy according to claim 12 wherein said relatively large contact and said relatively small contact are contiguously formed on said contactor, whereby said contacts are caused to engage substantially adjacent portions of said electrically conductive member.

3. A dual purpose electrical contact element for use in efiiciently making and breaking either high or low current electrical energy comprising in combination, an elongated arcuate contactor formed of resilient material one end of which is attached to an electrically conductive mounting member, a relatively large contact mounted on said contactor at the other end thereof for engagement with an electrically conductive member to conduct therebetween electrical energy of predetermined high current, the resiliency of said contactor providing the contact force urging said large contact toward engagement with said electrically conductive member, and a relatively small contact on said contactor at said other end thereof oifset from said large contact to normally engage said member due to the resiliency of said contactor urges said small contact into engagement with said member to conduct low current energy therebetween and urges said large contact into engagement therewith upon consumption of said smaller contact to conduct high current energy with said member.

4. A dual purpose electrical contact element for use in efiiciently making and breaking either high or low current electrical energy comprising in combination, a contactor, a relatively large contact on said contactor having a large contact surface for engagement with an electrically conductive member to efficiently conduct therebetween electrical energy of predetermined high current, and a relatively small contact on said contactor adjacent said large contact and offset therefrom to normally engage said member and thereby prevent engagement of said large contact therewith, said small contact having a relatively small contact surface sufliciently smaller than said large contact surface to cause said small contact to be consumed by heat generated by conduction of said predetermined high current energy between said small contact and said electrically conductive member to thereby permit said large contact to engage said electrically conductive member, whereby said small contact is operable to conduct low current energy and said large contact to conduct said high current energy with said member.

5. A dual purpose electrical contact element for use in efliciently making and breaking either high or low current electrical energy comprising in combination, an elongated arcuate contactor formed of resilient material one end of which is attached to an electrically conductive mounting member, a relatively large contact on said contactor at the other end thereof having a large contact surface for engagement with an electrically conductive member to efficiently conduct therebetween electrical energy of predetermined high current, and a relatively small contact on said contactor at said other end thereof adjacent to said large contact and offset therefrom to engage said member under the influence of said resilient contactor to thereby prevent engagement of said large contact with said member, said small contact having a small contact surface sufficiently smaller than said large contact surface to cause said small contact to be consumed by heat generated by conduction of said predetermined high current energy between said small contact and said electrically conductive member to thereby permit said resilient contactor to cause said large contact to engage said electrically conductive member, whereby said resilient contactor firstly causes said small contact to engage said electrically conductive member and thereafter said large contact to engage said member after said small contact is consumed by heat of said predetermined high current energy therethrough.

References Cited by the Examiner UNITED STATES PATENTS 2,528,086 10/1950 Schenck 200-166 3,180,961 4/1965 Waldorf 200-166 KATHLEEN H. CLAFFY, Primary Examiner.

BERNARD A. GILHEANY, HERMAN O. JONES,

Assistant Examiners.

Claims (1)

1. A DUAL PURPOSE ELECTRICAL CONTACT ELEMENT FOR USE IN EFFICIENTLY MAKING AND BREAKING EITHER HIGH OR LOW CURRENT ELECTRICAL ENERGY COMPRISING IN COMBINATION, A CONTACTOR, A RELATIVELY LARGE CONTACT ON SAID CONTACTOR FOR ENGAGEMENT WITH AN ELECTRICALLY CONDUCTIVE MEMBER TO EFFECIENTLY CONDUCT THEREBETWEEN ELECTRICAL ENERGY OF PREDETERMINED HIGH CURRENT, AND A RELATIVELY SMALL CONTACT ON SAID CONTACTOR OFFSET FROM SAID LARGE CONTACT TO NORMALLY ENGAGE SAID MEMBER AND THEREBY PREVENT ENGAGEMENT OF SAID MEMBER BY SAID RELATIVELY LARGE CONTACT, SAID SMALL CONTACT BEING SUFFICIENTLY SMALLER THAN SAID LARGER CONTACT TO BE CONSUMED BY HEAT UPON CONDUCTION THERETHROUGH OF SAID PREDETERMINED HIGH CURRENT ENERGY, WHEREBY SAID SMALL CONTACT IS OPERABLE TO CONDUCT LOW CURRENT ENERGY AND SAID LARGE CONTACT IS OPERABLE TO CONDUCT HIGH CURRENT ENERGY WITH SAID MEMBER.

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