US 3752942 A
A differential pressure switch comprising a one-piece rigid flat pivoted switch-actuating disc member isolated from the high and low actuating pressures by rolling diaphragms respectively carried by the housing of the pressure switch on opposite sides of and engaging opposite sides of the pivoted member. A compression coil spring biases the pivoted member against the action of the higher actuating pressure and a threaded seat for this spring serves to adjust the spring force applied to the pivoted member.
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Description (OCR text may contain errors)
United States Patent 1 McAfee [451 Aug. 14, 1973 DIFFERENTIAL PRESSURE SWITCH WITH PIVOTED ONE-PIECE RIGID FLAT SWlTCH-ACTUATING DISC MEMBER CAPTURED BETWEEN TWO ROLLING DIAPHRAGMS  Inventor: Darrell F. McAfee, Artesia, Calif.
 Assignee: DeLaval Turbine, Inc., Princeton,
 Filed: Mar. 10, 1972  Appl. No.: 233,584
 US. Cl. 200/83 Y, 200/83 A, 92/98 D  Int. Cl. H01h 35/34  Field of Search 200/83 Y, 83 D, 83 A,
 References Cited UNITED STATES. PATENTS 2,645,248 7/1953 Baker 200/83 Y X 10/1959 Kaatz 200/83 Y X 3,591,051 7/1971 Mitchell et a1 222/56 3,591,741 7/1971 Tuthiil 200/83 S 2,149,068 2/1939 Paul et a1 200/83 S X FOREIGN PATENTS OR APPLICATIONS 825,519 12/1959 Great Britain 200/83 Y Primary ExaminerJ. V. Truhe Assistant ExaminerRobert A. Vanderhye Att0rney--Ford W. Harris, Jr. et a1.
[ ABSTRACT A differential pressure switch comprising a one-piece rigid flat pivoted switch-actuating disc member isolated from the high and low actuating pressures by rolling diaphragms respectively carried by the housing of the pressure switch on opposite sides of and engaging opposite sides of the pivoted member. A compression coil spring biases the pivoted member against the action of the higher actuating pressure and a threaded seat for this spring serves to adjust the spring force applied to the pivoted member.
4 C1aims,.6 Drawing Figures Patented Agg. 14, 1973' 2 Sheets-Sheet 1 Patented Aug. 14, 1973 2 Sheets-Sheet 2 EKG-5.
1 DIFFERENTIAL PRESSURE SWITCH WITH PIVOTED ONE-PIECE RIGID FLAT SWITCH-ACTUATING DISC MEMBER CAPTURED BETWEEN TWO ROLLING DIAPI'IRAGMS BACKGROUND OF INVENTION The present invention relates in general to switches and, more particularly, to a switch responsive to the pressure differential between relatively higher and relatively lower actuating pressures.
SUMMARY AND OBJECTS OF INVENTION The primary object of the present invention is to provide a differential pressure switch wherein a one-piece rigid flat pivoted switch-actuating disc member is isolated from the relatively higher and relatively lower actuating pressures by rolling diaphragms respectively carried by the housing of the device on opposite sides of and engaging opposite sides of the pivoted member.
Another important object is to provide a spring engaging the pivoted member and biasing same in one direction, and means for adjusting the force applied to the pivoted member by the spring.
Another object is to provide a device wherein the spring is a compression coil spring acting on the pivoted member in a direction resisting the action of the higher of the actuating pressures, and wherein the adjusting means is a seat for the spring threadedly connected to the housing.
A further object is to provide a differential pressure switch of the foregoing nature wherein the pivoted member includes a disc shaped portion engaged by the rolling diaphragms.
Yet another object is to provide a differential pressure switch wherein the pivoted member includes a leaf spring engaging the switch of the device.
The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in the differential pressure switch art in the light of this disclosure, may be achieved with the exemplary embodiments of the invention illustrated in the accompanying drawings and described in detail hereinafter.
DESCRIPTION OF DRAWINGS but respectively illustrating alternative embodiments of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF INVENTION Referring initially to FIGS. 1 to 4 of the drawings, the differential pressure switch of the invention which is illustrated therein is designated generally by the numeral l and includes a housing 12 having therein a chamber 14 containing a switch actuating member 16 pivotally connected to the housing by a pivot 18. The member 16 is provided adjacent the pivot 18 with a leaf spring 20 engageable with a microswitch 22 within the housing 12.
High and low pressure ports 24 and 26 communicate with the chamber 14 on opposite sides of the switch actuating member 16. Rolling diaphragms 28 and 30 respectively engage opposite sides of a circular, disc shaped portion 32 of the pivoted member 16 adjacent the respective ports 24 and 26, the high and low pressures respectively acting on the diaphragms 28 and 30. These diaphragms are provided with annular ribs 34 and 36 respectively encircling the disc 32 and are provided with peripheral beads 38 and 40 respectively disposed in annular grooves within the housing 12 to pro vide fluid tight seals. As will be apparent, the high and low pressure components of the fluid pressure differential which actuates the differential pressure switch 10 are applied to the respective diaphragms 28 and 30 through the respective ports 24 and 26.
The high pressure component of the fluid pressure differential is resisted by a compression coil spring 42 one end of which is disposed in a spring seat 44 connected to the pivoted member 16 by a screw 46. An 0- ring around the screw 46 engages the pivoted member 16 and the diaphragm 30 to provide a fluid tight seal. The other end of the spring 42 is disposed in a cup shaped seat 50 threaded into the housing 12. As will be apparent, the spring force applied to the pivoted switch actuating member 16 may be adjusted readily by screwing the seat 50 in or out, thereby adjusting the pressure differential required to actuate the microswitch 22.
It is thought that the operation of the differential pressure switch 10 will be apparent from the drawings and the foregoing description, so that a detailed explanation is not required. The invention provides a very simple and reliable differential pressure switch 10 the moving parts of which are sealed by the rolling diaphragms 28 and 30, and which may be adjusted very readily by means of the threaded spring seat 50.
The differential pressure switch 10 is intended for use with relatively low pressure differentials. FIGS. 5 and 6 respectively illustrate differential pressure switches 110 and 210 intended for use with intermediate and relatively high differential pressures. The differential pressure switches 110 and 210 are very similar to the switch 10 and corresponding components will be identified by reference numerals respectively higher by and 200 than the reference numerals used in connection with the switch 10.
In the switch 110, the pivot 118 is located on the opposite side of the disc shaped portion 132 from the leaf spring 120, and the microswitch 122 is located on the opposite side of the leaf spring, all as compared to the switch 10. With this construction, the lever arm on which the pressure differential force acts is reduced to permit handling higher pressure differentials than the switch 110.
In the switch 210, the arrangement is basically the same as the switch 10, but the size of the disc shaped portion 232 is considerably reduced, and it is considerably closer to the pivot 218, again as compared to the switch 10. This has the effect of further reducing the lever arm on which the differential pressure switch acts to permit handling even higher pressure differentials.
Although exemplary embodiments of the invention have been disclosed for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims appearing hereinafter.
1. In a differential pressure switch, the combination a. a housing;
b. a switch actuating member in said housing in the form of a one piece rigid flat circular disc having a lateral extension;
c. means mounting said actuating member insaid housing for .pivotal movement relative thereto about a pivot axis spaced radially outwardly from the periphery of said discin said lateral extension and parallel to the faces of said disc;
d. rolling diaphragms respectively carried by said housing on opposite sides of and engaging the opposite faces of said disc;
e. said diaphragms respectively having annular ribs encircling said disc and disposed between the periphery of said disc and said housing, said pivot axis being spaced radially outwardly from said annular ribs;
f. ports in said housing and respectively communicating with said diaphragms on the opposite sides thereof from said disc; and g. a switch carried by said housing and engageable by said actuating member at a point spaced from said pivot axis. 2. A differential pressure switch as defined in claim 1 including:
a. a spring engaging said disc and biasing said actuating member in one direction; and b. means for adjusting the force applied to said disc by said spring. 3. A differential pressure switch as set forth in claim 2 wherein:
a. said spring is a compression coil spring having one end seated against said disc; and b. said adjusting means comprises a seat for the other end of said spring threadedly connected to said housing. 4. A differential pressure switch as defined in claim 3 wherein said actuating member includes a leaf spring engaging said switch.