US3519773A - Dual-throw switch - Google Patents

Description

y 7, 1970 B. KLIMEK 3,519,773

DUAL-THROW SWITCH Filed Aug. 28, 1968 2 Sheets-Sheet 1 [/VVAWTOF. f L57 MW MM 1)} I", i" {I} B. KLIMEK DUAL-THROW SWITCH July 7, 1970 2 Sheets-Sheet 2 Filed Aug. 28, 1968 fi l M W 5: I a f 49% United States Patent O US. Cl. 200-83 9 Claims ABSTRACT OF THE DISCLOSURE A dual-throw switch having a spring arm urged toward one contact by air pressure and toward another contact by a yielding member. In one form the contacts are designed to insure continuous engagement of the spring arm with one or the other contact, each contact separating from the arm when the arm has moved beyond the effect of the spring tension in the contact. In another form an insulating abutment serves to separate the contact from the arm.

The present application is a continuation-in-part of application, Ser. No. 727,856, filed May 9, 1968, and entitled Dual-Throw Switch.

SUMMARY OF THE INVENTION A flexible switch arm is movable in response to fluid pressure above a predetermined level toward one of two contacts. A diaphragm exposed to fluid pressure on one of its sides is enclosed within a housing and provided with a spherical seat. On its other side the diaphragm engages a spherical-surfaced member which in turn engages the switch arm for movement thereof toward said one contact, the switch arm engaging member and diaphragm being urged in the opposite direction by a yielding member to move the switch arm toward another contact. In one form the contacts are themselves yieldingly urged additionally toward engagement with the switch arm whereby the switch arm will be in engagement with both contacts or with one or the other of said contacts at all times. In another form, a piston subject to fluid pressure urges the switch arm in one direction and a spring urges the arm in the opposite direction and an insulating abutment extends between the opposed, leaf spring supported contacts to insure separation of a contact from the arm at a predetermined point of the excursion of said arm in either direction.

The invention relates to switches, and has particular relation to fluid pressure responsive switches useful, for example, in illumination of vehicle stop lights and the like.

One purpose of the invention is to provide a positiveacting, dual-throw switch responsive to fluid pressure.

Another purpose is to provide a positive-acting, dual throw stop light switch having means adjusting the action thereof.

Another purpose is to provide a fluid pressure responsive stop light switch having means insuring passage of electrical energy therethrough.

Another purpose is to provide a dual-throw switch having a movable switch arm responsive to fluid pressure and contact members yieldingly urged toward engagement with said switch arm.

Another purpose is to provide a dual switch having a switch arm and a pair of contacts yieldingly engaging said arm and including abutment means insuring separation of one of said contacts at a predetermined point in the excursion of said arm in either of two opposite directions.

Another purpose is to provide a dual-throw, fluid responsive switch of maximum simplicity and minimum cost in construction and an extended useful life.

Other purposes may appear from time to time during the course of the specification and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated more or less diagrammatically in the accompanying drawings wherein:

FIG. 1 is a side view with parts in cross section and parts out of normal position for clarity;

FIG. 2 is a top plan view with a cover removed;

FIG. 3 is a detail view of a variant element of the invention with the parts thereof shown in differing positions;

FIG. 4 is a view of a further variant form of the invention; and

FIG. 5 is another view of the form illustrated in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and particularly to FIG. 1, numeral 1 generally designates a housing. A fitting 2 is secured to the housing for delivery thereinto of fluid pressure through inlet passage 3 to a chamber 4. A diaphragm 5 divides chamber 4. One face of diaphragm 5 is presented to inlet 3 and to a spherical seat 6 formed on fitting 2 about the inner end of passage 3. The diaphragm 5 has its periphery suitably clamped between a fitting flange 2a and an internal housing part 7.

The opposite surface 8 of diaphragm 5 is presented for contact with a spherical end surface 9 of a motion-transmitting member 10. The member 10 has a rectilinear extension 11 traversing a correspondingly formed opening 12 in member 7.

Member 7 forms, with a second internal housing part 15, a switch chamber 16. Cover or closure part 17 is secured to housing 1 to close its end opposite that which carries fitting 2. A flexible switch arm 18 is formed of a metal strip having the general nature of a leaf spring and extending across chamber 16 and fulcrummed or supported by abutment 7a formed on part 7 at one side of chamber 16. An end portion of arm 18 extends upwardly through closure 17 from abutment 7a to form the external terminal 20. At its opposite end the arm 18 carries a double-sided contact element 21. Intermediate the portion of arm 18 extending across chamber 16, the arm 18 has an oflset or upwardly disposed dimple 22, as the parts are shown in the drawings. Extension 11 has a correspondingly conical end portion 11a positioned for engaging within the dimple 22 from beneath the arm 18 as the parts are shown in the drawings. A yielding member, such as spring 25, is positioned in chamber 16 and engages the arm 18 about the dimple 22 and on the surface of arm 18 opposite that presented to member 10. A threaded element 26 extends through cover 17 and engages retainer 27 for adjustment of the effect of spring 25.

In spaced vertical alignment with switch arm contact element 21 is a first contact member 30 which is in turn carried by terminal strip 31. Strip 31 extends through a curved path within an upper area of chamber 16, as the parts are shown, and then bends upwardly through cover 17 to provide an external terminal portion 32, the curved portion of strip 31 being indicated at 31a in FIG. 2.

Similarly, a second contact member 40 is positioned in vertical alignment with and beneath contact element 2.1, as the parts are shown, contact 40 being carried by terminal strip 41. The strip 41 in turn extends in a generally curved path through a lower portion of chamber 16 and then bends upwardly to extend through cover 17 and to provide the external terminal 42, the curved portion of strip 41 being indicated at 41a in FIG. 2.

Referring now to FIG. 3, a variant form of a portion of the invention is illustrated wherein the portion 31a of arm or strip element 31 which extends through the upper portion of chamber 16 is indicated at 31b and is curved of flexed downwardly to provide a spring action and an urging of contact member 30 downwardly toward contact element 21. Similarly, the portion 41a of arm or strip element 4.1 is, in FIG. 3, shown at 41b and as curved or bent upwardly to urge contact member 40 toward contact element 21. In the left-hand portion of FIG. 3 the contact element 21 is shown as beginning its movement beyond the midpoint of its traverse and toward its position when a predetermined pressure is present at inlet 3 both contact members 30 and 40 are in engagement with contact element 21.

In the right-hand portion of FIG. 3 the contact element 21 is shown in its lowermost position or in the position it occupies when the parts are in the position shown in FIG. 1.

Referring now to FIGS. 4 and 5, it will be observed that switch arm 118 has one of its ends secured as at 107 to an electrical energy supplying post 120 extending through and outwardly of housing 101. Arm 118 carries oppositely disposed contact elements 12.1 at its opposite end for positioning between contact members 130 and 140, the latter being carried in vertical, opposed, spaced alignment by the distal ends of crescent-shaped, leaf spring arms or strip elements 131, 141, respectively. The opposite ends of arms 131, 141 are secured to terminal connectors or posts 132, .142, respectively. A piston 105 carrying seal 105a is movable in chamber 104 in one direction in response to fluid pressure entering inlet 103 of fitting 102 to urge arm 118 in said direction. Arm 118 and piston 105 are urged in the opposite direction by spring 125, the effect of which is adjustable through means 126.

In the form of FIGS. 4 and 5, which may be a preferred embodiment under given circumstances, an abutment member 150 is secured within housing 101 and includes a portion 151 extending into the area between the opposed distal end surfaces of arms 131, 141, said arms having widths sufiiciently greater than the diameters of contact members 130, 140 to provide for such extension of abutment 150 without engagement of abutment .150 and members 130, 140. The thickness or vertical extention (as the parts are shown) of portions 151 is predetermined in relation to the area between opposed end portions of arms 131, 140, and thus to the combined thickness of contact elements 121 and contact members 130, 140, to insure contact of one of said ends of arms 131, 1-41 at the precise point desired in the excursion of arm 118 in either opposite direction.

Whereas there has been shown and described an operative form of the invention, it should be understood that this showing and description are to be taken in an illustrative or diagrammatic sense only. There are many modifications in and to the invention which will be ap parent to those skilled in the art and which will fall within the scope and spirit of the invention.

The use and operation of the invention are as follows:

It will be understood that fitting 2 is suitably connected to the fluid pressure brake system (not shown) of the vehicle and particularly, for example, to the emergency fluid brake pressure system. Contact member 30 is connected, by suitable electrical conductors (not shown) attached to its terminal portion 32, to the vehicle stop light through the electrical system, switches and the like, incorporated in the normal service brake system of the vehicle. Contact member 40 is in turn connected to the vehicle stop light. Terminal 20 of switch arm 18 is similarly provided for delivery of electrical energy to switch arm 18 and contact element 21.

So long as fluid pressure above a predetermined, safe level is present in the emergency fluid pressure brake system, said pressure delivered at inlet 3 will hold diaphragm 5 away from its seat 6 and will, through the mediacy of member 10, hold the switch arm 18 upwardly as the parts are shown, to maintain contact element 21 in engagement with contact member 30, the eflect of spring 25 being predetermined and set by means 26 in relation to said desired fluid pressure. Thus electrical energy will be supplied through the vehicle stop light switch of the service or normal brake system whenever the vehicle operator actuates the brakes through the normal service brake system.

Should there be a failure in the emergency fluid pressure brake system, however, the rapid diminution of fluid pressure from inlet 3 causes a downward move ment, as the parts are shown, of diaphragm 5, member 10 and switch arm 18 into the position shown, for example, in FIG. 1. The spherical seat 6 and surface 9 of member 10 provide for minimum wear of the diaphragm 5 as it moves toward and away from inlet 3.

With the parts thus in the position of FIG. 1, contact element 21 is in engagement with contact member 40 and the vehicle stop light is illuminated, it being understood that through appropriate automatic valving elements forming no part of the present invention and therefore not illustrated, the vehicle brakes will be applied in response to said loss of fluid pressure in the emergency brake system and the engagement of contact element 21 with contact member 40 insures the signaling of such brake application by illumination of the vehicle stop 1i ht.

While it can be anticipated that the loss of fluid pressure from the emergency brake system occurs rapidly and that valving elements (not shown) of such system insure a rapid diminution or dumping of said fluid pressure and the movement of contact element 21 from engagement with member 30 and across the space between contact member 30 and contact member 40 will consequently be very rapid, it is conceivable that the lack of engagement of contact element 21 with either member 30 or member 40 could produce a momentary nonillumination or blinking of the vehicle stop light and a momentary failure to signal the fact of brake application in response to loss of emergency pressure.

Since the lack of signal for even such short interval could be considered unsafe, there is disclosed the form of elements of the invention illustrated in FIG. 3. In this form the contact member arm portions 31b, 41b are curved or bent toward each other and toward the opposite contact surfaces of element 21 in the nature, for example, of leaf spring elements. So curved, the portions 31b, 41b provide for simultaneous engagement of both contact members 30 and 40 with element 21 when element 21 is in its intermediate position or in substantially the midpoint of its traverse.

Thus, upon loss of fluid pressure at inlet 3, for example, contact arm 18 and element 21 will move downwardly as the parts are shown in the drawings in response to the action of means 25 and against the yielding or spring action of strip portion 41b as illustrated in the right-hand portion of FIG. 3. In the initial portion of said downward movement of element 21, member 30, under the influence of strip portion 31b, will follow and remain in contact with member 21 until the limit of the spring action in strip portion 31b is reached. At that point, contact element 21 will remain in engagement with contact member 40 but will have separated from contact member 30. It will be understood that the same action occurs when contact element 21 and arm 18 are moved upwardly, as the parts are shown, in response to delivery of fluid pressure at inlet 3. The left-hand portion of FIG. 3 illustrates the condition prior to separation of contact member 40* from element 21.

Thus the form of FIG. 3 insures against a null position of contact element 21, even for a momentary period. The structure of FIG. 3 insures also against any maladjustment or lack of engagement between member 21 and the appropriate contact member 30 or 40 in response to maladjustment of parts or the presence of an undesirable intermediate fluid pressure at inlet 3.

Similarly, the form of FIGS. 4 and 5 insures against said null position and maladjustment or intermediate pressure conditions. Additionally, abutment 150 insures a positive, absolute, snap-action separation of a contact member from its associated contact element when arm 118 has moved a predetermined distance in either direction. The dimensions of abutment portion 151 are minutely controlled and related to arms 131, 141 and contacts 121, 130, 140 to insure such separation at the precise point desired. Abutment 150 obviates any difliculty which could ensue after substantial use of arms or strip elements such as those shown at 31b, 41b and the possible loss of spring effect in said arms. Abutment 150' may be supplied with portions 151 of varying vertical (as the parts are shown) extension to provide desired separation points and to accommodate Wear of contact elements 121 and contact members 130, 140, thus extending the useful life of the device of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A dual throw switch including a housing, a pressure-responsive member in said housing, an inlet positioned in said housing to deliver fluid pressure to one side of said member to urge said member in one direction, a switch arm extending across the opposite side of said member and carrying at its free distal end a doublesided contact element, yielding means engaging said switch arm beyond said pressure-responsive member to urge said arm and member in an opposite direction, first and second contact members positioned each on one side of and in alignment with said contact element, said contact element being movable into contact with both or with one or the other of said contact members in response to delivery of fluid pressures at predetermined levels at said inlet.

2. The structure of claim 1 wherein said switch arm constitutes an elongated leaf spring member having said double-sided contact element at said distal end, the opposite end of said leaf spring member extending outwardly of said housing and providing an electrical terminal.

3. The structure of claim 1 characterized by and including an offset portion intermediate the ends of said switch arm, said pressure-responsive member having an end surface formed and adapted for engaging and seating within said offset portion.

4. The structure of claim 1 characterized by and including a concave seat surrounding said inlet, said pressure-responsive member includes a diaphragm and a motion-transmitting member, said concave seat being 6 positioned to receive one surface of said diaphragm, said motion-transmitting member having a convex surface in engagement with the opposite side of said diaphragm.

5. The structure of claim 1 characterized by and including a strip element carrying at one of its ends said first contact member, a second strip element carrying at one of its ends said second contact member, said strip elements being each bent toward said switch arm whereby said contact members are yieldingly urged toward engagement with said contact element by said strip elements.

6. The structure of claim 5 wherein the inherent spring efiect of each of said strip elements is related to the excursion of said switch arm to insure separation of said contact element from one of said contact members after a predetermined movement of said contact members away from said one contact member.

7. The structure of claim 3 wherein said offset portion constitutes a spherical dimple presenting a concavity to said motion-transmitting member and characterized by and including a conical end configuration on said motiontransmitting member formed and adapted for seating within said concavity.

8. The structure of claim 1 wherein said contact members are carried by opposed leaf spring strip element portions and characterized by and including an abutment member formed of insulating material and extending into the area between said opposed strip portions, said strip portions individually, alternatively contacting said abutment to separate a contact member from said contact element in response to movement of said switch arm beyond a predetermined point in the excursion of said switch arm in either direction.

9. The structure of claim 8 wherein said abutment portion is dimensioned in relation to the thickness of said contact members and contact element to insure said separation at said predetermined point.

References Cited UNITED STATES PATENTS 2,647,968 8/1953 Byam. 2,934,618 4/ 1960 Beller et al. 2,939,928 6/1960 Learn. 3,153,708 10/1964 Guthrie.

ROBERT K. SCHAEFER, Primary Examiner H. R. SCOTT, Assistant Examiner US. Cl. X.R. 200-166

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