US3412355A - Automotive flasher device - Google Patents

Description

Nov. 19, 1968 c. F. FREY AUTOMOTIVE FLASHER DEVICE Filed Sept. 8, 1966 INVENTOR CLEON F. FREY l/larvqs Fig.4.

United States Patent 3,412,355 Y AUTOMOTIVE FLASHER DEVICE 'Cleon F. Frey, Sebastian, Fla., assignor to Come] International Corporation, Bayamon, Pnerto Rico, a corporation ofPuerto Rico Continuation-impart of application Ser. No. 523,752, Jan. 28, 1966. This application Sept. 8, 1966, Ser. No. 578,024

2 Claims. (Cl. 337-82) ABSTRACT OF THE DISCLOSURE A flasher utilizing a bimetal blade and a snap acting mechanism mounted on a chassis. The chassis in addition to providing a heat sink for the bimetal blade alsoserves as a source of heat for a compensating bimetal. The chassis also includes a tab member having a U-shaped loop intermediate its length. This U-shaped portion serves as a means for adjusting the timing cycle of the flasher by permitting the chassis to be shifted relative to a fixed contact and by permitting the length of the bimetal blade in contact with the heat sink to be varied.

This application is a continuati-on-in-part of mypatent application Ser; No. 523,752, filed Jan. 28, 1966, now abandoned and titled, Automotive Flasher Device.

The invention of the present application relates generally to intermittently operated electrical switch devices and inparticular to an automatic flasher for intermittently operating automotive lamps used as directional signals or emergency indicators.

Flasher devices for automotive use must meet rigid specifications as to service life, cycle time, satisfactory performance over a wide range of ambient temperature, etc. For example, such devices for the normallyclosed contact type must open its contacts within one second after voltage is applied, must have a flashing rate of 60 to 120 flashes per minute, with an on-off time ratio of 30% to 70%, at a voltage of 11 to volts DC and over an ambient temperature range of 0 to 125 F. Further, the device should preferably operate at the same cycling rate over 'a wide ambient temperature range, that is, at a uniform cycling rate at cold start and after prolonged operation. These requirements must be met by a device which lends itself to mass production and which can be produced at relatively low cost.

It is the primary object of the present invention to provide a flasher device capable of meeting the requirements referred to above and which can be mass produced and calibrated for various cycle characteristics at relatively low cost.

It is a further object of the present invention to provide a flasher device in which the movable contact carrying element utilizes a generally U-shaped member for snapping the contact element over center in a wide excursion to separate the contacts with a snap action, the U-shapcd member pivoting on a compensating bimetal support.

A further object of the present invention is to provide a flasher device utilizing a portion of its chassis as a heat sink for the thermally responsive element, thereby reducingits cooling time and hence the cycle time, of the flasher, the heat sink thus provided serving also as a source of heat for a compensating bimetal which resets the device to operate at a constant recycling rate even though the operating interval is prolonged.

These and other objects will become apparent as the description proceeds with reference to the accompanying drawings in which:

FIG. 1 is a top plan view of a flasher structure embodying the present invention.

FIG. 2 is a side view of the structure shown in FIG. 1 with the outer cover shown in broken lines.

FIG. 3 is a side view of the structure of FIG. 1 taken from the side opposite that shown in FIG. 2.

FIG. 4 is an end view of the structure shown in FIG. 1 taken from the right hand end.

Referring to the drawings, the structure includes a base 10 formed of a suitable phenolic or other electrical insulating material and a generally L-shaped chassis element 11 rigidly mounted on the base. As may best be seen in FIGS. 2 and 3, an electrical terminal forming bracket 12 extends from the base for connection to external wiring (not shown). The bracket 12 hasv tabs 12a which extend above the base. one of the tabs gripping the base portion 11a of the chassis element. The opposite end of the base portion 11a of the chassis element is secured to the base by means of a rivet 13. Between the rivet and the base portion 11a of the chassis element there is a tab having an upwardly looped portion of the chassis element of reduced cross-section, indicated at 11c, the looped portion of the tab providing an excess of material permitting limited shifting or displacement of the chassis element after rivet 13 is in place. The portion 110 provides a means by which the chassis element 11 may be shifted somewhatupon the base 10 so as to change the position of the chassis with relation to the fixed electrical contact to be subsequently described.

Attached to the vertical portion 11b of the chassis element is a switching element 16 formed by an auxiliary bimetal element or compensator 19, a detent element taking the form of a resilient, U-shaped blade 18, and a bimetal blade 17. The bimetal compensator is fixedly attached at its proximal end to one face of the vertical portion 11b of the chassis element and is oriented so that its high expansion side is closest to the vertical portion 11b of the chassis element. The bimetal blade 17 is fixedly attached to the other face of the vertical portion 11b of the chassis element by means of a rivet 14 and is oriented so that its low expansion side faces the vertical portion 11b of the chassis element. The resilient blade 18 is pivotally connected at one end to the remote end of the bimetal compensator 19, forming a fulcrum point 20, and is pivotally connected at its other end to thefree end of the bimetal blade 17, forming a pivotal point 21.

Referring to the bimetal compensator 19 in more detail, it consists of a proximal portion, a V portion and a remote portion, and serves, as previously pointed out, to pivotally support one end of the resilient blade 18. The proximal portion of the bimetal compensator 19 is longer than the remote portion thereof and has tabs 19a which extend above the upper margin of the vertical portion 11b of the chassis element. The bimetal compensator is anchored to the vertical portion 11b of the chassis ele- .ment by means of a relatively broad tab 11d on the vertical portion of the chassis element which is folded over the upper margin of the proximal portion of the bimetal compensator between the tabs 190, the flanges of puncture holes 22 (FIG. 3) in the base portion 11a of the chassis element serving to retain the base of the compensator 19. The compensator bimetal 19 is thus contiguous with the vertical portion 11b of the chassis element over a relatively large surface providing for good heat transfer between these elements for a purpose to be subsequently mentioned. The remote portion of the bimetal compenstor 19 has its central portion cut away to form legs 25 and a bridging or end element 30.

The bimetal blade 17 curves outwardly from the vertical portion 11b of the chassis element as will be evident from FIG. 1. Its free end is restrained by an electrical contact to be subsequently described, and is bifurcated, :as may best be seen in FIG. 2, to accommodate a tab Patented Nov. 19, 19 68 3 extending from one end of the resilient blade 18, the arrangement being such as to provide the previously mentioned pivotal connection 21 between the bimetal blade and the resilient blade.

The resilient blade 18 has a generally U-shaped configuration and is resiliently bowed so that it has a tendency to decrease its curvature and therefore exerts forces upon the pivotal connections at each of its ends which are substantially equal in magnitule 'and opposite in direction. The pivotal connection 20 between the bimetal compensator 19 and resilient blade 18 is provided with an electrically insulating barrier in the form of a *leaf of electrical insulating material 23. The leaf is generally disc-shaped, having a central hole and having a pair of diametrically opposed notches in its outer margin. As may best be seen in FIG. 4, the leaf of electrical insulating material is attached to the end of the resilient blade by means of a tab 24 connected through the central hole in the leaf 23 by any suitable means, spotwelding for example, the leaf thus being held between the tab 24 and the resilient blade 18 and the shape of tab 24 being such that it does not engage the bridging portion 30 of the resilient blade. The diametrically opposed notches in the outer margin of the leaf of electrical insulating material accommodate the legs 25 of the remote portion of the bimetal compensator 19 (FIG. 4) and serve to prevent lateral or vertical movement while freely allowing pivotal movement of the resilient blade 18 with re spect to the bimetal compensator 19 at the fulcrum point 20, there being no electrically conducting engagement of elements 18 and 19 across the pivotal connection.

On the bimetal blade 17 and near its free end is mounted an electrical contact 24, and adjacent to the contact 24, is a fixed contact 26. The fixed contact is supported on a tab 26a extending through the base and integral with a connecting terminal 27 depending from the base adjacent to the terminal member 12. The contacts 24 and 26 are preferably formed of platinum coated silver or palladium coated silver, and in such form, the contacts will not Weld or wear over the prolonged service life of the flasher.

In operation, when the circuit connected to the terminal members 12 and 27 is energized placing an electrical voltage across these terminals, electrical current flows through the chassis element 11, bimetal blade 17, and the contacts 24 and 26. The current through the bimetal blade causes the temperature of the bimetal blade to rise. The differential expansion of the two surfaces of the bimetal blade causes it to warp in contact-opening direction, this motion being initially resisted by the force exerted by resilient element 18. Eventually the deflecting force of the bimetal blade 17 overcomes the restraining force exerted by element 18. As soon as contact opening movement of blade 17 begins the force exerted by element 18 in contact-opening direction sharply decreases because of the shift in position of pivot point 21. This rapid unbalancing of these opposing forces causes contacts 24 and 26 to open with a snap action. Opening of the contacts 24 and 26 places the bimetal blade 17 in engagement with, and in good thermal conducting relation to, the adjacent face of the vertical portion 11b of the chassis element 11.

Separation of the contacts 24 and 26 breaks the circuit through the bimetal blade 17, stopping the electrical heating of the bimetal blade. Because of the blades engagement with the heat sink or thermal mass formed by the chassis element 11, the bimetal blade cools very rapidly and, in cooling, differentially contracts to move the switching element 16 from its open position to its closed position. This action is initially resisted by the resilient element, and when the fulcrum point 21 moves past the center of support, is assisted by the resilient element, thus providing a snap action to the closing of the electrical contacts 24 and 26. The closing of the electrical contacts 24 and 26 reinstates the flow of electrical currepeated.

As will be evident from FIG. 2, the bimetal blade is of relatively thin cross-section so that it has a relatively small thermal inertia and operates near the maximum temperature to which the current load will carry it to provide proper operation of the flasher over the required, relatively wide ambient temperature range of 0 to F. The arrangement of the resilient blade 18 and its U-shaped configuration causes the excursion of the movable contact 24, as the switching element moves from its contacts-closed position to its contacts-open position, to be relatively wide even though the switching element it relatively short in length. This wide excursion of the switching element in moving between its positions referred to above obviates the need for critical adjustment of the contact spacing so that the terminals can be mounted on a base formed of relatively low cost material. The mounting of the moving parts perpendicular to the plane of the base 10, and relatively close to the base, prevents any bending or deforming of the terminal members 12 and 27, externally of the control, from changing or shifting the contact operating point. This wide excursion of the switching element further provides a distinctly audible click as the contacts are transferred between open and closed positions, such audible response generally being a requirement for automotive flashers. The thermally conductive engagement of the bimetal blade with the adjacent face of the chassis element serves to rapidly drain away heat from the bimetal blade after the contacts are opened and serves to reduce the offtime of the flasher and hence the total cycle time. The means (looped portion 11c) permitting shifting of the chassis with relation to the fixed contact 26 provides a means for varying the length of the bimetal blade in contact with the vertical portion 11b of the chassis element during the closed-contact portion of the cycle, and for shifting the axis of support nearer or farther away from the fixed contact 26, and thus provides a means for limited adjustment or calibration of the cycle time.

Assuming no ambient temperature compensation, the heating and cooling time of the bimetal blade would be affected. At low ambient temperatures, the time required to heat the bimetal blade to its contact-opening temperature is longer, and the time interval required to cool the bimetal blade so that it will return to the closed-contact position is shorter, compared to corresponding conditions at high ambient temperatures. This results in the opencontact portion of the cycle being lengthened at high ambient temperatures and shortened at low ambient temperatures. Conversely, the closed-contact portion of the cycle is shortened at high ambient temperature and lengthened at low ambient temperature. Also the closed contact portion of the cycle is shortened at high ambient temperature (occurring, for example, because of heat accumulation during prolonged cycling) and lengthened at low ambient temperatures. There is an overall lengthening of the cycle time at high ambient temperatures because the cooling time of the bimetal blade is more affected by the ambient temperature than is its heating time. The undesirable effects are substantially eliminated by the use of the bimetal compensator 19.

Referring to FIG. 1, as the ambient temperature increases, the differential expansion of the bimetal compensator moves the pivot point 20 downwardly, thus shifting the axis of support of the switching element to increase slightly the effective force exerted by blade 18 in contact closing direction thereby compensating for the tendency of the closed contact portion of the cycle to decrease with increasing ambient temperature. Con-- versely, as the ambient temperature decreases, the end element of the bimetal compensator moves upwardly, thus shifting the axis of support of the switching element to decrease the effective force resisting opening of the contacts. The configuration of the bimetal compensator, as shown in FIG. 1, is such that it shifts the axis of support, effectively shifting the direction of the forces exerted by the resilient blade, in such a manner that the undesirable variations in cycle time are substantially cancelled out, thus providing a switching element which produces a switching cycle wherein the contacts-closed time is constant and the cycling rate is substantially constant over the entire ambient temperature range of 0 to 125 F.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in this art and within the broad scope of the invention, reference being made to the appended claims.

The invention claimed is:

1. A flasher device of the type wherein a base plate carries a flexible blade which controls an electrical circuit and is alternately moved between closed contact and open contact positions in response to the condition of the circuit, the improvement comprising mounting said flexible blade rigidly upon a chassis element, said chassis element having a base portion overlaying the flasher device base plate and being rigidly secured to the base at spaced mounting points, fastening means securing said chassis element base portion to the base plate, one of said mounting points on the chassis element base portion being located in an extending tab of reduced cross-section and an intermediate area of said tab being bent to provide an excess length of material permitting limited shifting of the position of the chassis element with respect to the flasher device base plate for calibrating adjustment.

2. A flasher device as claimed in claim 1 in which the excess material at said extending tab is provided by looping said tab upwardly away from the flasher device base plate in said area intermediate the length of the tab.

References Cited UNITED STATES PAT ETNS 2,271,485 1/1942 Koci 200l22.4 2,429,784 10/1947 Whitted et al 200113 X 2,786,171 3/1957 Clark 200138.5

BERNARD A. GILHEANY, Primary Examirier.

F. E. BELL, Assistant Examiner.

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