US 3501605 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
March 17, 1970 H. D. HUTCHINSON ET AL v 3,501,605
FLOW RESPONSIVE SWITCH MEANS Filed June 26, 1968 '0 Ill/III/III/ INVENTORS HAROLD D. HUTCHINSON WILLIAM C. GREGGE BY I F|G. 4 Z/Joifa Q42 a A7701? EYS United States Patent Office 3,501,605 Patented Mar. 17, 1970 3,501,605 FLOW RESPONSIVE SWITCH MEANS Harold D. Hutchinson and William C. Gregge, both of 903 Colorado Ave., Santa Monica, Calif. 90404 Filed June 26, 1968, Ser. No. 740,162 Int. Cl. H01h 35/40 US. Cl. 20081.9 6 Claims ABSTRACT OF THE DISCLOSURE A switch housing including an enclosure is provided for insertion in a fluid line such that if the fluid flow through the enclosure drops below or rises above a predetermined flow rate, the switch in the housing will be actuated. This actuation is accomplished by an arm passing from the interior to the exterior of the enclosure through a bore in a wall portion of the enclosure which arm will transfer motion imparted to the inner portion of the arm by fluid flow to the outer portion of the arm by a rocking movement. The outer portion of the arm upon being rocked as a result of a change in fluid flow rate actuates the switch. The portion of the arm passlng through the bore in the wall is surrounded by an annular resilient material to provide a fluid tight seal and yet permit the rocking movement. Further, a rigid transverse pin passes through the resilient material and arm portion in a direction at right angles to the axis of the bore and the direction of fluid flow, the ends of the pin extending beyond the resilient material to engage opposite interior wall portions of the bore in such a manner as to be blocked against translatory movement in a direction towards the exterior of the enclosure. The pin thus defines a pivot axis for the rocking movement and also prevents the resilient sealing material from being blown out when the fluid pressure in the enclosure exceeds the exterior pressure.
This invention relates generally to flow responsive switches and more particularly to an improved switch means for insertion in a fluid flow line wherein the switch is actuated whenever the fluid flow rate drops below or rises above a predetermined flow rate.
BACKGROUND OF THE INVENTION In our United States Patent 3,345,478 there is disclosed and claimed a flow responsive switch for providing an indication of a change in flow rate in a fluid line. As described in this patent, the structure also functions to actuate a switch whenever the fluid flow rate drops below a given value. For example, in a liquid cooling line, should the flow rate of coolant drop below a given value overheating of a piece of equipment may result. In such instance, use of a flow responsive switch connected to deenergize the equipment in question should the flow of cooling fluid drop below a given rate would be very advantageous.
The flow responsive switch of our above-noted patent incorporates a unique orifice means wherein orifices of different sizes may be positioned to intercept the fluid flow and result in a pre sure differential constituting a function of the flow rate. This pressure differential causes movement of a diaphragm which movement in turn is transmitted to the exterior of the flow system to actuate the switch in question. A particularly important feature of the invention of this patent resides in utilizing a rocking arm structure passing through a wall of the enclosure incorporating the orifice, there being provided an annular resilient seal ofiering very little resistance to this rocking movement. Thus the transference of the motion of the diaphragm to the exterior of the structure can be accomplished with very little friction to the end that accuracy results.
The structure as described above has proved extremely effective and has constituted a great advance in the art for flow responsive switches particularly wherein the flow rate is small; for example, five gallons per minute or less. There are many situations, however, where fairly large flow rates; for example, up to thirty-two gallons per minute require proper monitoring. In these instances, two major problems have been encountered. First, the flow rates involved can oftentimes result in relatively large pressures within the enclosure which tend to pop out the the annular seal surrounding the portion of the rocking arm passing through the wall of the enclosure. Efforts heretofore to anchor this arm in place have resulted in increasing the resistance to rocking movement resulting in inaccuracies. Second, the counterforce spring associated with such systems and connected to the exterior portion of the rocking arm to counteract the physical movement taking place within the enclosure has had to be changed to change the counterforce when different flow ranges are involved. This is a consequence of the particular type of physical movement generated in the enclosure in response to flow rates.
BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention contemplates an improved flow responsive switch means over that shown and described in our prior patent wherein the foregoing two difliculties are overcome.
More particularly, the invention contemplates a fluid enclosure having an inlet and outlet for insertion in a fluid line. This enclosure incorporates orifice means at the inlet area defining an orifice of a. first given cross-sectional area through which the fluid passes. Means are provided in the enclosure responsive to a given change in fluid flow rate through the orifice for effecting a given physical movement in the enclosure. In the preferred embodiment, this means takes the form of a circular disc secured to the interior portion of an arm means in a position with its plane normal to the direction of fluid flow to intercept the fluid flow. The disc has a fixed cross-sectional area and can cooperate with different orifice means of smaller and larger cross-sectional areas that may be inserted in the enclosure. The arm itself extends through a wall of the enclosure to the exterior thereof and will rock about the point that it passes through the wall in response to movement of the disc by the flow of fluid. The exterior portion of the arm is positioned to actuate a switch such that should the flow rate drop below a given flow rate, the switch will function to, for example, shut off a piece of equipment. This exterior portion of the arm is subject to a biasing counterforce as by a spring. However, it is not necessary to replace this spring by springs of other spring constants in order to increase the range of fluid flow monitoring. Actually, it is only necessary to change the orifice size to increase the range of flow rates detectable by the apparatus the diameter of the disc on the interior portion of the arm remaining the same. In other words, the geometry of the structure is such that a greatly increased range of fluid flow rates can be monitored by the flow switch apparatus; for example, from less than five gallons per minute to up to thirty-two gallons per minute.
The present invention further contemplates the provision of a unique sealing and pivoting means at the area of the wall through which the arm passes to permit rocking movement of the arm with very little friction. This sealing and pivoting means includes an annular resilient material filling the annulus defined between the exterior portion of the arm passing through the inner wall and the bore in the inner wall receiving the arm. This annular resilient material provides a tight seal and yet permits rocking movement in a manner similar to the sealing structure described in our heretofore mentioned United States patent. However, the structure further includes a rigid transverse pin passing through the resilient material and portion of the arm in a direction at right angles to the axis of the bore in the wall and the direction of fluid flow. The ends of this pin extend beyond the resilient material to underlie opposite interior wall portions of the bore in such a manner that the pin is blocked against translatory movement toward the exterior.
With the foregoing arrangement, extremely high pressures as well as high flow rates within the enclosure can be tolerated without risk of the seal for the arm blowing out. Yet there is still provided the advantage of a substantially frictionless pivoting action of the arm through the wall.
BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the preferred embodiment of this invention will be had by now referring to the accompanying drawings, in which:
FIGURE 1 is a perspective view of the fiow responsive switch means inserted in a fluid line;
FIGURE 2 is a cross section of the flow switch taken in the direction of the arrows 22 of FIGURE 1 showing the device prior to insertion in a fluid line;
FIGURE 3 is a fragmentary cross section taken in the direction of the arrows 33 of FIGURE 2; and,
FIGURE 4 is a greatly enlarged cross section of the central portion of FIGURE 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGURE 1 the flow switch includes a central frame structure provided with a cover 11 and a lower portion 12 constituting an enclosure. This enclosure has inlet and outlet portions 13 and 14 for insertion in a fluid line 15. As will become more fully evident as the description proceeds, the interior of the structure under the cover 11 includes a switch arranged to be actuated whenever the fluid flow rate through the line 15 drops below a predetermined value. Electrical output leads for this switch are indicated at 16 and may be connected, for example, to apparatus to be shut down whenever the flow rate drops below such predetermined value. Alternatively, the leads 16 may connect to a suitable indicating means such as a light or buzzer to indicate a change in the flow rate from a desired value.
Referring now to FIGURE 2, the enclosure 12 of FIG- URE l defines a hollow interior 17 communicating with the inlet 13 and outlet 14. An orifice means 18 is shown at the inlet area 13 and defines an orifice 19 of given cross-sectional area. This orifice means 18 is removably secured in the enclosure and includes an O-ring 20 for sealing purposes so that all fluid flow is directed through the orifice 19. The orifice itself may include an annular groove 21 for receiving a key or pin 22 passed through a portion of the enclosure 12 to secure the orifice 18 in position. A different orifice means may be substituted for the orifice 18 by simply disassembling the device and removing the pin 22. The substituted orifice means may have an orifice of either smaller or larger cross-sectional area.
Extending into the enclosure 17 is the lower portion of an arm means 23. This lower portion serves to support a drag means in the form of a disc 24 of given diameter. This disc is positioned with its plane normal to the direction of fluid flow such as to intercept fluid flow from the orifice 19.
As shown in FIGURE 2, the arm means extends through a wall area incorporating a sealing and pivoting means designated generally by the numeral 25. The upper portion of the arm exterior of the enclosure 17 is indicated at 26. This portion of the arm connects to a biasing means in the form of a spring 27. The free end of the spring connects to a carriage 28 which may be movably positioned along a track 29 as by a screw 30. Access to the screw 30 may be had through a small opening 31 in the cover 11. By this arrangement, the counterforce exerted by the spring 27 on the upper portion 26 of the arm may be adjusted by proper threading of the screw 30.
A suitable contacting area designated 32 on the upper portion of the arm 26 opposite the point of connection of the spring 27 is positioned to engage a microswitch operating arm 33 extending from a microswitch 34. The leads 16 described in FIGURE 1 connect to the switch 34 as shown. In FIGURE 2, the area exterior to the enclosure is designated generally by the numeral 35, this area accommodating the switch and spring structure normally disposed beneath the cover 11.
FIGURE 3 illustrates the disc 24 in full plan View and it will be noted that this disc has a given diameter D relative to the diameter d of the orifice 19 of FIGURE 2. For fairly small flow rates for example, from four to eight gallons per minute, the orifice diameter d will be less than the disc diameter D. For flow ranges for example from eight to sixteen gallons per minute, the orifice diameter d will approach the diameter D of the disc, and for large flow rates of the order from sixteen to thirtytwo gallons per minute, the orifice diameter d will be larger than the disc diameter D. The force of the fluid impinging upon the disc 24 will determine the deflection or physical movement of the lower portion of the arm 23 counter to the biasing of the spring 27 connected to the upper portion. For a first given flow rate, the tension exerted by the spring 27 may be adjusted to result in a deflection of the exterior portion 26 of the arm sufficient to actuate the switch for any value of flow rate within the first range. For a second range such as described wherein a different sized orifice is substituted, there will generally be no requirement for changing the spring 27, the deflection being substantially the same but the dilference in the flow rate range being accommodated by the change in relative diameters between the orifice and the disc. Thus, the disc diameter D may be kept constant throughout various flow ranges for the instrument it only being necessary to change the overall range by changing the orifice itself. Further, the geometry is such that a relatively wide range of flow rates can be monitored.
The foregoing constitutes an important feature of the invention. Thus, the net effect of the change of the orifice diameter with flow rate relative to the disc diameter D is to maintain the range of force applied to the element 23 essentially constant for each flow range, i.e. the maximum and minimum force applied to element 23 over the flow ranges 4-8 g.p.m., 8-16 g.p.m., 16-32 g.p.m., etc. is the same for all flow ranges. Since the force range applied to element 23 is constant the balancing spring force applied to 26 is likewise constant over the various flow ranges thus allowing one spring to function over a very wide total flow range. The unique feature of changing d while D is held constant is to reduce the effective area of the jet (formed by orifice 19) intercepted by disc 24 as the flow rate increases thus limiting the range force applied to 24 as the flow increases.
FIGURE 4 illustrates in greatly enlarged view the area of the enclosure wall 12 through which the arm passes. As shown in FIGURE 4, this area is defined by a bore 36 passing through the wall portion of the enclosure defined by the frame 10. This bore has a relatively large entrance portion facing the enclosure interior 17. This entrance portion decreases in diameter as indicated at 37 in FIGURE 4 to define a first annular ledge 38 facing the interior 17 of the enclosure. The reduced diameter portion 37 in turn is again decreased in diameter as indicated at 39 to define a second annular ledge 40 also facing the interior portion 17 of the enclosure. An annular resilient material 41 surrounds the portion of the arm 23 passing through the bore structure and provides a seal therefor. As shown, the upper portion adjacent to the exit end of the bore structure of this resilient material is engaged by the second annular ledge 40. The lower portion of the resilient material 41 in turn is engaged by a washer 42 arranged to press up against the material 41 as by means of suitable screws 43. Thus, the resilient material 41 is sandwiched between the upper face of the washer 42 and the second annular ledge 40.
A portion of the arm 23 passing through the bore struc ture includes a transverse opening 44 receiving a rigid transverse pin 45 passing through the resilient material 41. The extreme ends of the transverse pin 45 extend beyond the resilient material 41 and engage or underlie the first annular ledge 38, this ledge defining suitable diametrically opposite positioned shoulder means. The direction of the transverse pin 45 is at right angles to the arm portion passing through the :bore structure and is also at right angles to the direction of fluid flow as will be evident from FIGURES 2 and 3.
The rigid transverse pin 45 constitutes an extremely important feature of this invention in that it accomplishes two purposes: first, it defines a pivot axis for rocking movement of the arm, the extreme ends of the pin itself simply rolling on the under shoulders defined by the first annular ledge 38; second, it positively prevents any blowing out of the resilient seal 41 and arm portion passing through the bore structure, the pin itself being blocked against translatory movement towards the exterior 35 of the enclosure because of its passage through the opening 34 in the arm and its end extensions beneath the first annular ledge.
Representative dimensions in fractions of an inch are given for the various bore diameters of the portions 36, 37, and 39. In addition, other representative dimensions in fractions of an inch or decimal parts thereof are shown for the thickness of the resilient material 41 and diameter of the transverse pin 45.
OPERATION In operation, the flow responsive switch means is inserted into a fluid line 15 by coupling the. line to the inlets 13 and 14. With reference to FIGURE 2, it will be evident that fluid flow through the line 15 of FIGURE 1 will all be confined to pass through the orifice 19 and some of the fluidflow will impinge on the face of the disc 24. There will thus be provided a force moment on the arm 23 tending to rock the same in a counterclockwise direction as viewed in FIGURE 2. The exterior portion 26 of the arm will thus engage the microswitch actuator 33 and close the microswitch 34 so that, for example, if the switch is included in a series power circuit to a piece of equipment, the equipment will be properly energized.
Assume for the sake of illustrative purposes that it is desired to automatically de-energize such equipment should the fluid flow rate drop below a given value. For this purpose, the tension exerted by the spring 27 of FIGURE 2 is adjusted to have a value such as to overcome the drag force exerted on the lower end of the arm 23 when the fluid flow rate drops below the preselected value. Under these conditions, it will be evident that the microswitch 34 will remain closed provided that the flow rate is sufiicient to rock the arm and hold it in its rocked position against the bias of the spring 27.
If the flow rate should drop below the selected value, the drag force on the lower end of the arm 23 will decrease. permitting the spring 27 to rock the arm in a clockwise direction and thus cause disengagement of theupper portion of the arm with the microswitch actuator 33. The microswitch will thus open and automatically shut down the piece of equipment to which it is connected.
' Alternatively, the microswitch may be a normally closed type switch which is held in open condition when the actuator 33 is engaged. In this event, when the flow rate drops below a predetermined value, the switch 34 will close and could be employed to energize a suitable indicator. In still another example, the switch 34 could be a normally open switch and connected to a suitable indicator which would be energized upon closing of the switch. The spring 27 could be adjusted in tension such that the arm portion 32 would not engage the switch until the flow rate increased beyond a given desired maximum value, this maximum being sufficient to increase the drag force to an extent that the microswitch actuator 33 will be engaged. The device will then indicate increase of flow rate beyond a desired value.
In all instance of operation, the switch may readily be accommodated to different flow ranges by simply substituting different sized orifices for the orifice means 18 all as described heretofore with respect to FIGURE 2. It should again be emphasized that changes in flow rate ranges can be effected without having to substitute a spring of different spring constant for the spring 27, the screw adjustment covering the range of each of the different ranges determined by the orifice size.
The actual rocking movement of the arm can be made fairly small by adjusting the proximity of the actuator 33 for the microswitch 34 to the upper portion 26 of the arm. Normally, the degree of rocking would not exceed four degrees. Over this rocking range, the annular sealing and pivoting structure 25 described in detail in FIGURE 4 operates extremely efliciently to provide the desired sealing and pivoting action even under conditions of very high prssure in the enclosure compared to the exterior pressure. In other words, there is very little frictional reistance afforded to the rocking movement when the range of rocking is small.
As already described heretofore, the unique provision of the rigid transverse pin in the bore hole structure as described in combination with the annular resilient material 41 assures that very little friction will result during pivoting movement and that the risk of blow out is minimal.
From the foregoing, it will be evident that the present invention has provided a greatly improved fluid flow responsive switch means wherein all of the various advantage, particularly the indepednece of calibration and sensitivity with time and enviroment, are fully realized.
What is claimed is:
1. A flow responsive switch means for insertion in a fluid flow line comprising, in combination:
(a) a fluid enclosure having an inlet and outlet for insertion into said flow line;
(b) orifice means at the inlet area of said enclosure defining an orifice of a first given cross-sectional area through which said fluid passes;
(c) means in said enclosure responsive to a given change in flow rate of fluid through said orifice for effecting a given physical movement in said enclosure;
(d) a switch positioned exterior of said enclosure;
(e) arm means passing through a wall of said enclosure to the exterior thereof in a direction substantially normal to the direction of fluid flow; and,
(f) sealing and pivoting means at the area of said wall through which said arm means passes to permit rocking movement of said arm means, the portion of said arm means interior of said enclosure moving in response to said given physical movement to thereby move the portion of said arm means exterior of said enclosure, said switch means being positioned to be actuated in response to movement of said portion of said arm means exterior of said enclosure, said area of said wall being defined by a bore of larger diameter than the portion of said arm means passing therethrough, said bore defining on inner diametrical- 1y opposite wall portions, shoulder means, said sealing and pivoting means comprising:
(1) an annular resilient material filling the annulus defined between the exterior of said portion of said arm means and inner wall of said bore'to provide a fluid tight seal and yet permit said rocking movement; and,
(2) a rigid transverse pin passing through said resilient material and portion of said arm means in a direction at right angles to the axis of said bore and the direction of said fluid flow, the ends of said pin extending beyond said resilient material to underlie said shoulder means in said bore,
whereby said pin defines a pivot axis for said rocking movement, and whereby said resilient sealing means is prevented by said pin from being blown out of said bore when fluid pressure in said enclosure exceeds the exterior pressure.
2. A flow responsive switch means according to claim 1, in which said first bore has a first given diameter at its entrance portion in the wall portion facing the interior of said enclosure, and thence decreases to a second given diameter to define a first annular ledge facing said entrance portion, diametrically opposite portions of said annular ledge defining said shoulder means.
3. A flow responsive switch means according to claim 2, in which said second given diameter decreases to a third given diameter at its exterior exit portion to define a second annular ledge facing said entrance portion, said resilient material underlying said second annular ledge; and a washer member surrounding said arm means s'paced slightly from said entrance portion and bearing against said resilient material to sandwich the same between said washer and said second annular ledge.
4. A flow responsive switch means according to claim 1, including adjustable biasing means connected to said arm means to exert a bias force on said arm means opposing said physical movement whereby a given force on said arm means must be exerted as a result of fluid flow,
suflicient to overcome said bias force in order to move said portion of said arm means exterior of said enclosure a suflicient distance to actuate said switch.
5. A flow responsive switch means according to claim 1, including removable means securing said orifice means in said enclosure such that said orifice means may be removed and replaced with another orifice means having an orifice of cross-sectional area diiferent from said first cross-sectional area.
6. A flow responsive switch means according to claim 5, in which said means in said enclosure responsive to a given change in flow rate of fluid through said orifice 'for effecting said given physical movement constitutes a disc secured to the interior portion of said arm means in a position with its plane normal to the direction of fluid flow to intercept said fluid flow, said disc having a fixed crosssectional area for cooperation with different orifice means of smaller and larger cross-sectional areas that may be inserted in said enclosure, whereby said orifice sizes may be smaller than said disc for monitoring low range flow rates, may approach. the size of said disc for medium range flow rates, and may be larger than said disc for high range flow rates so that the range of forces applied to said disc is substantially the same for each flow range.
References Cited UNITED STATES PATENTS 2,740,858 4/1956 Euler 200-8l.9 3,119,979 1/ 1964 Martin 2008l.9 XR 3,126,463 3/1964 Kmiecik 200-8l.9 3,260,815 7/1966 Trimmer 20081.9 3,291,495 12/1966 Liebig 277174 XR 3,364,454 1/1968 Froebe 277l74 XR 3,369,089 2/ 1968 Hellman ZOO-81.9
ROBERT K. SCHAEFER, Primary Examiner J. R. SCOTT, Assistant Examiner U.S. Cl. X.R. 277-174