US 3535479 A
Description (OCR text may contain errors)
Oct. 20, 1970 w. H. SMYERS, JR,- ET AL 3,535,479
TIME DELAY PRESSURE SWITCH Filed June 7, 1968 2 Sheets-Sheet 1 AWE/v TORS WILLIAM H. SMYERS,JR.B| RONALD DELANEY v .arrom v/s'r Oct. 20, 1970 w. H. SMYERS, JR, ET AL 3,535,479
TIME DELAY PRESSURE SWITCH Filed June 7, 1968 2 Sheets-Sheet :3
FIG- 3 United States Patent O 3,535,479 TIME DELAY PRESSURE SWITCH William H. Smyers, Jr., Wethersfield, Conn., and Ronald E. DeLaney, Dayton, Ohio, assignors to Koehler- Dayton, Inc., Dayton, Ohio, a corporation of Ohio Filed June 7, 1968, Ser. No. 735,364 Int. Cl. H01h 35/40 US. Cl. 200-83 8 Claims ABSTRACT OF THE DISCLOSURE A time delay pressure switch which opens and closes electrical circuits in response to increases and decreases in pressure in a fluid conduit. The switching action is immediate upon increase in pressure, and when the pressure is relieved from the fluid conduit the switch is not returned to its original position until a predetermined time has expired. This predetermined time is adjustable by bleeding air slowly into the actuating chamber of the switch.
BACKGROUND OF THE INVENTION In many modern appliances and other processing de vices, liquids and other fluids are frequently pumped from one place to another, for example, a washing machine or a chlorinator used to process human waste in a small pleasure boat. The pressure in a liquid or column of air is often used to initiate a subsequent cycle in the processing equipment, and therefore pressure switches which sense an increase in pressure are utilized for this purpose. However, it is frequently necessary to continue operation of the subsequent cycle even after the pressure in the fluid conduit has been substantially reduced so that all of the liquids or fluids in the downstream cycle are processed. Thus the standard pressure actuated switch is unsatisfactory for such an installation.
SUMMARY OF THE INVENTION A time delay switch adapted for mounting in a fluid conduit and having an auxiliary chamber defined between two flexible members which separates the fluid from the switch. The first flexible member operates a switching mechanism which moves contacts between at least two alternate positions to shift the electrical switch. An enclosed switch chamber houses the switching components, and the first flexible member forms one wall of this switch chamber. When pressure is increased in the auxiliary chamber causing movement of the first flexible member, the pressure in the switch chamber is automatically and quickly removed through a one-way check valve. However, when pressure is relieved in the auxiliary chamber air flows very slowly through an adjustable orifice into the switch chamber so that the first flexible member and the switch do not return to their original position until a preset time has elapsed.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view takenthrough the time delay switch in accordance with the invention;
FIG. 2 is a view similar to FIG. 1 but showing the switch in an alternate position;
FIG. 3 is a plan view of the switch;
FIG. 4 is a sectional view through the one-way check valve taken along the line 4-4 of FIG. 3.
FIG. 5 is a sectional view through the variable orifice taken along the line 5-5 of FIG. 6; and
FIG. 6 is a sectional view taken along the line 66 of FIG. 5.
Patented Oct. 20, 1970 DETAILED DESCRIPTION OF THE INVENTION Referring to FIGS. 1 and 2, the pressure switch 10 includes a lower housing 11 adapted to be mounted in a fluid conduit 12, such as a water line or the like, whose pressure is to be used to actuate the switch. The lower housing 11 may be mounted in the conduit 12 so that the fluid flows through the pressure chamber 13 on its way to subsequent process steps. The lower housing 11 is dish shaped with an opening 14 in the top thereof and an annular flange 15 extending around the outer edges thereof to support the periphery of the resilient diaphragm 16 which encloses the top of the lower housing to define the pressure chamber 13. The diaphragm 16 is preferably constructed of a corrosion resistant material and is sufficiently flexible so that it expands upwardly upon pressurization of the chamber 13.
The diaphragm 16 is clamped in position by the upper housing 18 which has an annular flange 19 similar in size and configuration to the flange 15 on the lower housing 11, as shown in FIGS. 1 and 2. The screws 21 extend through the flanges 15 and 19, through suitable openings 22 in the diaphragm 16 to receive the nuts 24 and thus to sandwich the outer periphery of the diaphragm therebetween, and create a fluid tight seal for the chamber 13 and between the upper and lower housings 10.
An electrical switch assembly 25 is secured in the upper housing 18 by the spacer sleeve 26 disposed between the diaphragm 16 and the gasket 26a against the switch assembly 25, as shown in FIGS. 1 and 2. An auxiliary chamber 27 between the diaphragm 16 and the rigid end wall 28 of the switch assembly is air tight. The assembly 25 also includes a molded plastic body 30 which forms the upper end of the assembly and has the annular ring 31 formed integrally thereon to provide the side Walls of the assembly 25 thereof. The resilient diaphragm 33 is disposed adjacent the rigid end wall 28 and is clamped in position on the annular ring 31 by deforming the periphery 35 of the metal end wall 28 around the ring 31 to clamp the diaphragm in place. When so mounted, an inner or loading chamber 37 is provided between the rigid end wall 28 and the diaphragm 33, and this inner chamber 37 communicates with the chamber 27 through the passage 38 formed in the short tube 39 in the center of the rigid wall 28 so that the rigid end wall 28 merely serves to provide a stop to downward movement of the diaphragm 33 and the chambers 27 and 37 act as one chamber.
A switch chamber 40 is defined in the interior of the body 30 and is sealed at its lower end by the diaphragm 33. This chamber contains all of the components of the switching mechanism including the metal disk 41 which engages the central portion of the diaphragm 33 and has the axially upwardly extending finger 43 which is urged downwardly toward the rigid wall 28 by the spring 44 interposed between the adjustable screw 46 in the bore 47 in the body 30 and the upper end 48 of the finger 43. This spring 44 urges the disk 41 and the diaphragm 33 downwardly, and any upward movement of the diaphragm 33 must compress this spring.
The main switch lever 50 is secured to the boss 51 formed in the body 30 and extends radially across the center of the chamber 40. An intermediate switch lever 52 is also provided on the boss 51 and extends inwardly centrally of the main lever 50 and has its innermost end in contact with the upper end 48 of the finger 43. The coil spring 54 is interposed between the ends 55 and 56 of the levers 50 and 52, respectively, so that upward movement of the finger 43 moves the intermediate lever 52 upwardly causing the right-hand end of the spring 54 to move above the end 55 of the main lever 50 to shift the latter downwardly against the contact 58. This contact is disposed on a contact lever 60 which is rigidly secured on the boss 61 and is adjusted by use of the screw 63 extending through the threaded bore 64 in the body 30 and into engagement of the inner end of the contact lever 60. By approximately turning the screw 63, the position of the contact 58 on the lever 60 is adjusted in a vertical direction, as viewed in FIG. 1.
When the finger 43 is moved downwardly, the right end of the spring 54 is returned to its initial position below the opposite end thereof causing the main switch lever 50 to be moved upwardly into engagement with the contact 66 secured to the body 30. The lever 50, contact lever 60 and contact 66 are connected to metal pins 67, 68 and 69' which extend through the body 30 and are connected to the 'metal terminals 71, 72, 73 for use in connecting the switch 10 in an electrical system.
A check valve 75 is provided in the thin top wall 76 (FIGS. 3 and 4) of the body 30 for permitting rapid venting of air from the switch chamber 40. This check valve may be of the umbrella type wherein the annular resilient valve member 77 is secured to the body 30 by inserting the stem 79 through an opening 80 in the wall 76. Since the end of the stem 79 is larger than the opening 80, the valve 75 is held securely in position. A series of vent openings 82 are also provided in the Wall 76 under the periphery 81 of the valve so that increased pressure within the switch chamber 40 can readily flow through these openings and around the upwardly deformed periphery 81 of the valve 75 before escaping to the atmosphere. When pressure is decreased in the chamber 40, the periphery 81 of the valve is forced downwardly against the wall 76 to seal the openings 82 and block the flow of air into the chamber.
An adjustable time delay vent 85 is also provided in the body 30 (FIGS. 3 and 6) for slowly bleeding air into the switch chamber 40. This vent includes an upstanding tubular extension 86 formed integrally with the wall 76 and having the passage 87 therein. The O-ring seal 88 is provided in the groove 90 in the exterior of the extension 86, and the nipple 92 is provided with a central bore 93 to fit over the extension 86 so that the seal 88 engages the inner surface thereof. The exterior threads 95 on the exterior of the nipple engage the similar interior threads 96 on the annular shoulder 97 of the body 30 so that rotation of the nipple effects movement thereof in a vertical direction.
A plastic insert 98 is provided in the nipple 92 and has the frusto-conical bore 99 therein for receiving the upper portion 100 of the extension 86. This plastic insert 98 is supported on the shoulders 102 of the nipple 92 and is clamped in position by the filter 103 which rests on the top surface 104 thereof. The perforated disk 105 covers the filter 103 and is held in position by deforming the upper edges 106 of the nipple inwardly to hold the filter and insert 98 in place.
The grooves 107 and 108 are provided in the plastic insert 98 and shoulder 102, respectively, so that air flows through the openings 109 in the disk 105, the filter 103, the grooves 107 and 108, and into the chambers 111 surrounding the upper portion 100 of the tubular portion 86. Accordingly, by rotating the adjustable nipple 92, the plastic insert '98 is moved in an axial direction so that the clearance between the upper portion 100 of the extension 86 and the adjacent walls 112 of the insert 98vary so that they decrease or increase the flow of air into the passage 87.
In operation of the switch 10, when the lower housing 11 is connected to the source of fluid under pressure, such as a pressurizing liquid, the chamber 13 causes the lower diaphragm 16 to be forced upwardly (FIG. 2). This transfers the air or other gas in the intermediate chamber 27 causing it to flow into the chamber 37 and force the diaphragm 3-3 upwardly. As the diaphragm 33 moves upwardly into the chamber 40, it likewise forces the disk 41 and finger 43 upwardly causing the main lever 50 to move the contact 55 from the contact 66 to the contact 58. As a result, a preset operation is commenced in accordance with the system in which the switch 10 is being utilized. Upward movement of the diaphragm 33 compresses the air within the switch cham ber 40 causing it to flow rapidly outwardly through the check valve 75 in the top Wall 76, as previously described.
When the pressure in the chamber 13 is relieved, for example, when the processing operation is almost complete, the resilient diaphragm 16 is urged toward its original position which reduces the pressure in the chamber 27 causing the pressure below the upper diaphragm 33 to be reduced. This pressure reduction and the spring 44 acting through the finger 43 and the metal disk 41 urge the upper diaphragm 33 downwardly toward its initial position. However, because the flow of air into the switch chamber 40 is blocked except for the vent 85, the diaphragm 33 cannot return to its original position until the precise time has elapsed which is required to bleed the necessary air into the chamber 40 and allow the diaphragm 37 to be returned to its original position. Thus, the vent is adjusted so that the air slowly bleeds through the openings in the disk 105, the filter 103, the grooves 107 and 108, the chamber 111 and the passage 87. By rotating the adjustable nipple 92, the rate which the air is bled into the switch chamber 40 can be adjusted as required by the system in which the switch 10 is mounted. It is also possible, to shut off completely the vent '85 so that the switch 10 does not return to its original position until the vent is manually opened once again.
Accordingly, the invention has provided a novel time delay electrical switch which quickly moves to one position but which has a precise time delay before shifting to an alternate position when pressure is relieved. Thus the electrical circuit for a subsequent operation remains complete and can continue to function even when the pressure has been relieved from the switch. While the invention has been shown and described as having a time delay in only one direction, it is possible to eliminate the check valve and provide a time delay in both directions prior to any movement of the switch contacts. Moreover, since the vent is adjustable, the delay time can be varied precisely. The particular arrangement of electrical switch connections and contacts in this invention are not limitations on the invention since other electrical switch elements can be used without departing from the scope of the invention.
While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.
What is claimed is:
1. A pressure actuated time delay switch comprising a housing, first flexible means separating the interior of said housing into first and second chambers and being urged toward a first position, means for connecting said first chamber to a source of fluid under pressure to move said first flexible means to a second position to decrease the volume of said second chamber, valve means leading from said second chamber to the atmosphere for permitting rapid venting of fluid from said second chamber at a first flow rate when said flexible means is moved in a direction which decreases the volume of said second chamber and for slowly bleeding fluids into said second chamber at a second flow rate appreciably less than said first flow rate to provide a gradual return in a preset time of said first flexible means to said first position when the pressure in said second chamber is reduced below a preset pressure, and electrical switch means controlled solely by said first flexible means for shifting electrical contacts as said first flexible means moves between said first and second position.
2. A time delay switch as defined in claim 1 wherein said valve means includes a separate one-way check valve operable to permit the rapid flow of air from said second chamber, and an adjustable vent means to regulate precisely the flow of air into said second chamber.
3. A time delay switch as defined in claim 1 wherein said electrical switch means includes at least two electrical contacts, a movable lever adapted to move between contact with said electrical contacts, and overcenter means for holding said lever in contact with one of said contacts at all times.
4. A time delay switch as defined in claim 1 wherein said housing includes an auxiliary chamber disposed between said first and second chambers, said auxiliary chamber being defined at one end by said first flexible means and at the other end by a second flexible means so that pressurization of said first chamber effects movement of said first flexible means while isolating said first flexible means from contact with the fluid under pressure.
5. A time delay switch as defined in claim 4 wherein a rigid support means is provided in said auxiliary chamber adjacent first flexible means for limiting movement of said first flexible means toward said rigid support means, and means defining an opening said rigid means so that said rigid means does not interfere with the flow of fluids in said auxiliary chamber.
6. A time delay switch as defined in claim 4 wherein said housing comprises a lower section which cooperates with said second flexible means to define said first chamber, and an upper section secured to said lower section which cooperates with said first and second flexible means and said electrical switch means to define said auxiliary chamber.
7. A time delay switch as defined in claim 1 wherein said first flexible means is a flexible diaphragm.
8. A time delay switch as defined in claim 4 wherein said first and second flexible means are flexible diaphragms.
References Cited UNITED STATES PATENTS 2,768,261 10/1956 Mathisen 92-37 XR 2,921,159 l/ 1960 Elderton et al. 3,237,646 3/1966 Houser et al. 3,240,895 -3/ 1966 Horowitz et a1. 3,442,180 5/1969 Babic 92-37 XR ROBERT K. SCHAEFER, Primary Examiner J. R. SCOTT, Assistant Examiner US. Cl. X.R. 92-37