US3293391A

US3293391A - Spiral bimetal operated coolant level switch

Info

Publication number: US3293391A
Application number: US428121A
Authority: US
Inventors: Marvin T Carlson
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1965-01-26
Filing date: 1965-01-26
Publication date: 1966-12-20
Anticipated expiration: 1983-12-20

Description

SPIRAL BIMETAL OPERATED oooLANT LEVEL SWITCH Filed Jan. 2e, 1965 Dec. 20, 1966 M. T. CARLSON 2 Sheets-Sheet 1 70 f1.5' G f8 INVENTOR. MV/N 7.' CARLSON Mp4/M ATTORNEV De- 20, 1966 M. T. CARLSON 3,293,391

SPIRAL BIMETAL OPERATED COOLANT LEVEL SWITCH Filed Jan. 26, 1965 2 Sheets-Sheet 2 INVENTOR. MARl//N 7.' CARLSON Elim@ f90/M ATTORNEY United States Patent O 3,293,391 SPIRAL BIMETAL OPERATED COOLANT LEVEL SWITCH Marvin T. Carlson, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation oi' Delaware Filed Jan. 26, 1965, Ser. No. 428,121 7 Claims. (Cl. 200-113) This invention relates to electrical switches and more particularly to a spiral, bimetal operated, cooltant level switch.

It is an object of the present invention to provide an improved Huid level switch that utilizes a heated bimetal immersed in the fluid whose level is to be monitored.

It is another object of the present invention to provide an improved fluid level switch wherein a spiral-shaped bimetal is utilized to provide the movement of a contact member during a switching action.

It is still another object of the present invention to provide an improved electrical `switch that is responsive to the temperature of a coolant in an engine cooling lsystem to provide a visual indication for a vehicle operator of a low coolant level.

Further objects and advantages of the present invention will be apparent from the following description,

yreference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is a diagrammatic illustration of the electrical circuit in which the subject invention is used, the invention being shown in an operative environment;

FIGURE 2 is a plan view of the subject invention, illustrated with parts broken away, thereby exposing the interior portion of the subject device;

FIGURE 3 is a sectional view of the subject invention taken along line 3-3 of FIGURE 2;

FIGURE 4 is a sectional view of the subject invention taken along line 4 4 of FIGURE 2.

Referring now to FIGURE 1, a switch body, generally designated by the numeral 10, is illustrated in a typical mounting position on an automobile vehicle engine wherein a portion of the switch extends into the cooling system of the engine. A battery 12 has one terminal grounded and another terminal conductively engaging a terminal 14 of the switch 10 through an ignition switch 16. A terminal 18 of the switch 10 grounds an indicating lamp 20 through the switch body. It is understood that the switch body is grounded to the vehicle engine.

Referring now to FIGURE 3, the terminal 14 is illustrated as being carried by a non-conductive portion 22 of the switch body 10. The portion 22 is formed integrally with the base of the switch and is composed of any well-known insulating material. A conductive rivet 24 firmly holds the terminal 14 engaged with the portion 22 and engages a conductive strip 26 on an opposite end. The conductive strip 26 furnishes a conductive path between the rivet 24 and a spiral-shaped bimetallic element 28. In FIGURE 3 it is seen that the bimetallic element 28 is suspended below the level of a fluid 30 carried in a fluid passage 32 of the vehicle engine.

Referring to FIGURE 4, the bimetallic element 28 is carried by a conductive post 34 which is secured to 3,293,391 Patented Dec. v20, 1966 ICC the bimetallic element at 36 so as to be non-rotatable with respect thereto. The conductive post 34 has a diameter 37 carried in an aperture 38 in the non-conductive portion 22 of the switch body 10. A diameter 40 of the conductive post 34 is carried in an aperture 42 in the portion 22 of the switch body 1 0. It is clear that the side of the aperture 42 provides a bearing surface for the conductive post 34 as it rotates during a switching action to be hereinafter described. A smaller diameter pocket 44, formed at the base of the aperture 42, is arranged to receive a sealing O-ring 46. The O-ring 46 is composed of any well-known elastomeric material and serves the dual purpose of providing a seat for the flat portion 48 of the post 34 disposed between the diameter 40 and the diameter 37 as well as sealing the cornpartment 50 from the fluid 30 in the cooling passage 32.

A resilient conductive member 52 is arranged to rotate with the conductive post 34, being secured thereto, and includes outwardly projecting

resilient legs

54 and 56. The leg 54 is adapted to maintain contact with a conductive wall 58 of the switch body 10 while the leg 56 is adapted to slide on the conductive wall 58 and selectively engage a contact rivet 60 which in turn conductively engages the terminal 18. It should be noted that the contact rivet 60 is mounted in an insulated manner with respect to the conductive wall 58 by being enclosed in a plug 62 formed of any well-known insulating material. The terminal 18 is insulatedly mounted with respect to the wall 58 by the insulating washer 64 disposed between the terminal 18 and the wall 58. The

conductive post 34 is piloted at its upper end by a portion 66 cooperating with a pocket 68 formed in the wall 58.

\ Referring to FIGURE 3, the switch body 10 is secured to a wall of the cooling passage 32 by means of bolts 70 compressing a gasket 72 between portions of the wall 58 and a wall 74 of the cooling passage 32.

Referring to FIGURE 2, the resilient conductive member 52 is illustrated as being connected to the conductive post 34. The leg 54 of the member 52 is limited in its movement in one direction by an outwardly projecting ange 76 integrally formed with the wall 58.

- When the leg 54 is moved in a counterclockwise direction, as viewed in FIGURE 2, to a point where it engages the rivet 60, the leg 54 will simultaneously engage the flange 76 to prevent any further movement thereof.

In operation, the ignition switch 16, illustrated in F-IG- URE 1, is closed and power is thereby provided to the terminal 14 and to the lamp 20. Referring to FIGURE 3, the power to terminal 14 is conducted through the rivet 24, through the strip 26, to the bimetal 28, and on through the conductive post 34, to the leg 54, to ground, as seen in FIGURE 3. The power thus provided heats the bimetallic element 28 and causes it to have a tendency to rotate on the axis of the post 34,

stantially the position Ashown by the solid lines in FIG- URE 2. It is seen therein that they member` 52 is out of engagement with the rivet 60 and, therefore, no current can llow through the ungrounded lamp 20.

When the temperature of the fluid 30 exceeds certain predetermined limits or the fluid in the passage 32 escapes, leaving the bimetallic element 28 exposed, the tendency of the element 28 to ro-tate on t-he axis of the post 34 will be realized, resulting in a movement of the member 52. 'Referring to FIGURE `4, it is seen that the fluid 30 lhas -receded below the depth to which the bimetallic element 28 is disposed and the leg 56 has moved strom the position shown in FIGURE 3 into conductive engagement with the rivet 60. In this situation, a parallel circuit is set up with the bimetallic element 28 still being heated and an Ialternate path for current flow provided through lamp 20, to the terminal 18, through the member 52 to ground. The lamp 20 is thereby grounded and becomes incandescent, alerting the operator of the vehicle to the tact that the temperature limits established for proper operation of the cool-ing system have been ex- 'ceeded .and maintenance is necessary. It is understood that the particular temperature ranges established for satisfactory operation of the cooling system are determined -by the design, and an appropriately operative bime- `tallic element 28 can be provided in a .given system to bring about the desired result.

T-he utility of the subject invention is extended due to its responsiveness both to a dropping of fluid level in a 'lluid chamber below the level of the bimetal as well as Ibeing responsive to the total absence of uid in the chamber. It is clear that the heat developed by the bimetal 28 can be dissipated by the iluid 30 under normal operating conidtions, but cannot be satisfactorily dissipated when the fluid level reccdes or the fluid temperature exceeds predetermined limits. Therefore, the subject device can be utilized as a level sensing mechanism by v suspending the biemta'llic element 28 down to a minimum determined level in a fluid container. In this instance, the temperature of the uid need not be controlling of the action of the bimetal, but the actual presence of the fluid surrounding the lbimetal is required in order to gain the required dissipation 4of heat.

While the embodiment of the present invention as here in disclosed, constitutes a preferred form, it is to be understood that other yforms might be adopted.

Wlhat is claimed is as follows:

1. A fluid level indicator comprising: a switch body; -rst terminal means carried through one wall of said switch body and adapted to conductively engage a power source; second terminal means carried in one wall of 4said switch body and adapted to electrically engage an indicator light, said se-cond terminal means having a conductive portion exposed within said switch body; Contact means pivotally supported by said switch body and including two outwardly projecting resilient legs, a first of said legs selectively engaging the exposed portion of the second terminal, a second of said resilient legs being arranged to maintain a conductive relationship between said switch body and a ground; and temperature responsive means carried by said contact means and including a portion in conductive engagement with the iirst terminal, said temperature responsive means having means arranged to pivot said contact means in response to a raising of temperature of a fluid thereby moving a first of said outl wardly projecting legs into conductive engagement with the second' terminal providing thereby a ground for the -light connected thereto.

2. A uid level indicator tor use with an automobile engine cooling system, said fluid level indicator comprisl ing: a switch body adapted to be mounted over an opening in the engine cooling system; a irst terminal adapted to electrically engage a power sour-ce and being mounted through one wall of said switch body; a vsecond terminal adapted to -conductively enga-ge an indicating device and being mounted through another wall of said switch body, said second terminal having a conductiveporticn exposed within said switch body; resilient contact means being pivotally supported by said switch body and including a portion projecting into thermal conductive Arelationship with iluid in the vehicle cooling system, a portion of said contact means selectively engaging said second terminal and another portion of said contact means being arranged to provide a ground 4for said first terminal thereby; and temperature responsive means carried by a portion of said contact means in the opening of the engine cooling system wherein a portion of said temperature responsive means is submerged in the lliuid therein and responsive to the temperature thereof, said temperature responsive means 'being heated by power through said rst terminal and thereby poised for deflection, said temperature responsive means being normally cooled by the lluid in lthe engine cooling system thereby preventing any deection during heating of said temperature responsive means, said temperature responsive means being delectable as cooling from the fluid in the engine cooling system is lost thereby rotating a portion of said contact means int-o conductive engagement with the second terminal thereby completing an electrical circuit to the indicating device.

3. A duid level indicator accor-ding to claim 2 wherein rthe temperature responsive means is a spiral-shaped bimetallic element carried by said contact means.

4. The lluid level indicator according to claim 3 wherein the spiral-shaped bimetallic element is heated and controllably mounted by engaging the rst terminal, said spiral-shaped bimetallic element being mounted at its center to said contact means.

5. A uid level indicator adapted for use with the cooling system of vehicle engines, said indicator comprising: an indicator body adapted to be mounted over an aperture in the engine cooling system; a rst terminal adapted to conductively engage a power source and be ing carried through one wall of said switch body; a second terminal adapted to cond-uctively engage an indicating device and bein-g carried through one wall of the switch body with a conductive portion disposed therein; said first terminal 'being insulatedly mounted with respect to said switch body, said switch body being grounded through the vehicle engine; resilient contact means being pivotally supported 'by a portion of said switch body and including a portion suspended in the engine cooling system to a level normally containing a iluid, said contact means Ihavirxg a resilient outwardly projecting portion selectively engaging the conductive portion of said second terminal `and havin-g a second outwardly projecting resilient portion slidably maintaining conductive relationship to the grounded portion of the switch body; and temperature responsive means carried by the portion of the contact means suspended in the engine cooling system `and having a second portion conductively engaging said insulated first terminal, power from the power source being supplied to the temperature responsive means through the insulated first terminal to ground, the heat generated thereby being normally dissipated by the -fluid in the engine cooling system, said contact means being selectively pivotable into conductive engagement with the second terminal when ll-uid reaches a level in the engine cooling system wherein the heat is not dissipated from the temperature responsive means, said pivoting contact means energizing a circuit through the temperature responsive means to the indicating device to alert a vehicle driver of a level in the engine cooling system below the suspended disposition of the temperature responsive means.

r6. The fluid level indicator according to claim 5 wherein the temeprature responsive means is `a spiral-shaped bimetallic element held at one end by the conductive engagement with the iirst terminal and held -at an opposite end by the portion of the contact means suspended in the liu-id of the engine cooling system, said temperature responsive means being thereby pivotable on its own axis against the xed mounting to the 'rst terminal.

7. The uid level indicator according to claim 6 wherein the Contact means is a conduct-ive element pivotally supported in a pocket integrally forme-d with a Wall 5 of said switch body, said integrally formed pocket having a multidiameter inner periphery, a smallest diameter of which is arranged to receive -a bearing O-ring and sealing element to support a langer diameter portion of the contact means in a [larger diameter portion of said 10 pocket.

References Cited by the Examiner UNITED STATES PATENTS 2,759,066 8/1956 Short et al. 200-138 3,001,052 9/1961 Swanson 200-138 3,081,393 3/1963 Wolhl 20G-138 BERNARD A. `GILHEANY, Primary Examiner.

T. MACBLAIN, Assistant Examiner.

Claims

1. A FLUID LEVEL INDICATOR COMPRISING: A SWITCH BODY; FIRST TERMINAL MEANS CARRIED THROUGH ONE WALL OF SAID SWITCH BODY AND ADAPTED TO CONDUCTIVELY ENGAGE A POWER SOURCE; SECOND TERMINAL MEANS CARRIED IN ONE WALL OF SAID SWITCH BODY AND ADAPTED TO ELECTRICALLY ENGAGE AN INDICATOR LIGHT, SAID SECOND TERMINAL MEANS HAVING A CONDUCTIVE PORTION EXPOSED WITHIN SAID SWITCH BODY; CONTACT MEANS PIVOTALLY SUPPORTED BY SAID SWITCH BODY AND INCLUDING TWO OUTWARDLY PROJECTING RESILIENT LEGS, A FIRST OF SAID LEGS SELECTIVELY ENGAGING THE EXPOSED PORTION OF THE SECOND TERMINAL, A SECOND OF SAID RESILIENT LEGS BEING ARRANGED TO MAINTAIN A CONDUCTIVE RELATIVESHIP BETWEEN SAID SWITCH BODY AND A GROUND; AND TEMPERATURE RESPONSIVE MEANS CARRIED BY SAID CONTACT MEANS AND INCLUDING A PORTION IN CONDUCTIVE ENGAGEMENT WITH THE FIRST TERMINAL SAID TEMPERATURE RESPONSIVE MEANS HAVING MEANS ARRANGED TO PIVOT SAID CONTACT MEANS IN RESPONSE TO A RAISING OF TEMPERATURE OF A FLUID THEREBY MOVING A FIRST OF SAID OUTWARDLY PROJECTING LEGS INTO CONDUCTIVE ENGAGEMENT WITH THE SECOND TERMINAL PROVIDING THEREBY A GROUND FOR THE LIGHT CONNECTED THERETO.