US3022396A - Readily adjustable pressure switch - Google Patents

Description

Feb 20, 1962 M. PACKER ETAL 3,022,395

READILY ADJUSTABLE PRESSURE SWITCH Filed Sept. l0, 1959 ATTORNEY United States Patent O M 3,022,396 READILY ADJUSTABLE PRESSURE SWITCH Morton Packer, 76 Kingsley Drive, Yonkers, N.Y., and James R. Arcara, 597 North Ave., New Rochelle, N.Y. Filed Sept. 10, 1959, Ser. No. 839,153 2 Claims. (Cl. 200-83) The present invention relates to a pressure responsive switch and, in particular, to a switch adapted to indicate the change of fluid or vapor pressure from a preselected value in a hydraulic, lubricant or cooling supply system for internal combustion engines employed in land, air or sea vehicles.

In the normal use of small craft boats propelled by inboard engines, the operator of the craft learns from experience to listen to the noise of the boat engine during its operation. Should the engine noise deviate or change from that normally expected of it, the operator, if he is prudent, will stop the engine to ascertain its trouble if any. Heretofore, this technique remained as the one reliable method for ascertaining within the very short time between commencement of trouble and resulting damage whether the lubricating or cooling system of the engine is subject to malfunction. However, should the craft operator misjudge or fail to recognize the audible warning caused by unusual engine noise and thus fail within a short period of time, perhaps three to five minutes, to stop the engine and repair the trouble or take other necessary steps, costly destruction of the engine usually results. Not infrequently, such malfunctions have led to dangerous explosions, fre and even loss of a boat. A1- though attempts have been made to provide crafts with malfunction warning systems to guide the operator, in particular the inexperienced boat operator, these systems heretofore have proved unsatisfactory.

It is the principal object of the invention to provide a pressure responsive switch which is reliable, simple and economical With respect to construction and operation, and which switch is adaptable for indicating malfunctions in a lubricating, cooling or hydraulic supply system for an engine and Which switch is particularly suitable for providing warning alarms with respect to engine system malfunction before serious trouble arises.

It is a further object of the present invention to provide a malfunction Warning system adaptable as a normally open electrical contact pressure switch during operation, the operation of which is regulated by a movable diaphragm. A switch in accordance with the invention is readily adjustable for operation over a Iwide range of pressures because activation of the diaphragm is controlled by its thickness and the size of its return spring. The switch is further characterized by instantaneous actuation upon malfunction of a pressure system and is unaffected by the iluid material flowing in the pressure system, that is to say, the switch is adaptable to sense uids or vapors such as oils, water, chemicals or any other medium capable of causing displacement of a pressure responsive diaphragm.

It is a further object of the present invention to provide a pressure sensitive switch for small craft boats and adapted to sense continuously pressure of the engine cooling or lubricant system, and hence eliminates the need of constant vigilance over the system. The switch is readily adapted to provide an audible or other type of warning signal instantaneously upon malfunction of the cooling or lubricant system of the boat engine. The switch is explosion proof and does not introduce any boat battery drain when the system is not indicating malfunction. The switch is equally adaptable for high voltage sources as well as low voltage sources and circuits, wherein its current rating may be regulated by 3,022,396 Patented Feb. 20, 1962 increasing or decreasing the amount of material making contact.

Further objects and advantages will become apparent from the following description of the invention taken in conjunction with the figures, in which:

FIG. l illustrates an elevation View, partly in section, of a switch in accordance with the invention; and

FIG. 2 illustrates the contact portion of the switch in make contact position.

Switch 10 is constituted by a housing made of an upper portion 11 and a lower portion 12 held together by spaced pairs of screw bolts and nuts, such as 13 and 14, one pair is shown in FIG. 1. In assembled relationship, the housing defines an interior chamber 15. A flexible disc-shaped diaphragm 16 and a juxtaposed relatively rigid washer 17 are supported at the top of chamber 15 wherein the contiguous peripheral edges of diaphragm 16 and washer 17 are clamped in an annular groove formed along chamber 15 by the assembled housing portions. The peripheral edges of diaphragm 16 and washer 17 are held in clamped fixed position by annular flanges 18a, 18b of the opposed coacting housing portions 11, 12. Washer 17 is dish shaped to form an annular depressed seat provided with a central opening 19 to support an electrical insulator member 20 having stepped diameter sections. The upper diameter section has a downward facing annular flange surface 21 'which rests upon the inner ledge of washer 17. Member 20 is axially dimensioned so that its top surface 22 is in pressed contact with diaphragm 16. A spring retainer 23 is mounted over the lower or smallest diameter section of member 20. Retainer 23 is spring loaded to bear against the downwardly facing confronting annular flange surface 24 of member 20. A spring 25 is held in compression between spring retainer 23 and a second spring retainer 26 at the lower end of the spring. Spring 25 is at all times in electrical contact with retainers 23, 26 since these elements are also a part of an electrical circuit, as will be seen hereinafter. Spring retainer 26 rests upon the top of an insulated bushing 27, which bushing has a downwardly projecting cylindrical portion carried in the internal bore of a sleeve 28. Sleeve may be made of any suitable material. Sleeve 28 is provided with an outer threaded surface 29 for engaging a threaded surface in a through opening in the bottom wall of housing portion 12. Retainer 26 is clamped against the ange of bushing 27 by the overlapping head of a screw bolt 30, which bolt extends through the bore of bushing 27 and also through the bore of a second bushing 31 having a longer cylindrical portion which is also carried in the internal bore of sleeve 28. Bushing 31 is also of insulating material. The confronting ends of the two bushings 27, 31 are spaced apart in the internal bore of sleeve 28. The lower end of bolt 30 carries a pair of nuts 32 for clamping an electrical wire lug 33 thereat and also for clamping bushing 31 against a bottom knob flange 34 of sleeve 28. Lug 33 is connected electrically in series to an electrical source 34, such as D.C. battery, Warning means 36, such as a light or alarm, and then ground at 37. Bolt and nut 13, 14 at the top of the housing is also grounded. When the electrical circuit is closed by the contact of retainer 23 and washer 17, the alarm or light 36 will provide a warning. The electrical circuit includes bolt 13, housing portion 12, Washer 17, retainer 23, spring 25, retainer 26, bolt 30, lug 33, battery 35, warning means 36 and ground 37. Consequently, the aforesaid housing portion, washer, retainers, spring, bolts constituting the switch structure are made of suitable electrical conducting material. Sleeve 28 and its assemblage is held to housing portion 12 by a nut 41.

Housing portion 11 has an internal chamber 38 communicating by way of passage 39 with the hydraulic coolant or vapor system to be sensed by switch 10. Accordingly, nipple 40 is adapted for attachment to the pressure system. Chamber 33 is on the upper side of diaphragm 16 and when switch 1G is attached to the pressure system, chamber 3S fills with the liquid or vapor and thus is subject to the pressure of the ud system, which pressure acts upon diaphragm 16 to ileX same downwardly. It will be understood that diaphragm 16 is so designed and, if desired, also washer 17, to seal chamber 38 from the lower portion of switch lil when the peripheral edges of diaphragm and washer are clamped by flanges 13a, 181). The midsection 20a of member 20 is of such axial length to prevent normally electrical contact of washer 17 and retainer 23 when diaphragm 16 exes downwardly to seat ange face 21 of member 20 on washer 17.

In operation, the uid pressure is sensed in upper chamber 38 at all times during operation of the engine. This pressure urges diaphragm 16 to iiex downwardly wherein diaphragm 16 in turn bears against insulating member 20 and forces same downwardly whereby retainer 23 assumes the position illustrated in FIG. 1. The electrical circuit is thus open because the two contact members thereof 17, 23 are spaced apart. When the pressure falls below a preselected value, and spring Z is adjusted to expand at this value of pressure, the pressure against the upper side of diaphragm 16 becomes less than the upward directed force of the preloaded spring Z5. Spring 25 then raises insulated member 20 o its seat in washer 17 and diaphragm 16 exes upwardly. This action brings retainer 23 in electrical contact with washer 17, whereby the warning signal, a light or alarm, goes on. It will be noted that the warning signal goes on as soon as the pressure in the system drops below its preselected value. Increase in pressure of the system above such value will instantaneously restore switch to its initial or normal oi condition since diaphragm 16 will then ex downwardly against spring 2S to push insulator body 20 downward to disengage the contacting members 17, 23 and thus break the electrical circuit.

One advantage of switch 10 is that it may be used with any type of pressure system and n'eed not be designed for a specific engine because the critical pressure at which spring 25 will respond may be adjusted by the boat, vehicle or aircraft operator by manually turning knob 34 on sleeve 28. Assuming a clockwise rotation, sleeve 28 and its attached assembly of bushings 27, 31, nuts 32, retainer 26 and bolt 30 will move up into housing chamber 1S which adds additional compression to spring 2S and thus increases its preload. In contrast, turning of knob 34 in the other direction lowers the force of preload. The pressure level at which spring 25 will become effective to raise diaphragm 16 and insulating body 20 from the position shown in FIG. 1 will be larger for a greater preload, that is to say, the contacting members 17, 23 will close at a higher pressure level than for a lower preload imparted to spring 25. Similarly, turning of sleeve 2S counterclockwise lowers the preload so as to result in a warning of at a lower pressure level.

ln addition, the resiliency of spring 25, its thickness and length, as well as the resiliency of diaphragm 16 may be selected to provide a particular pressure range for switch operation, whereby pressures over a wide range may be sensed and controlled by a particular design for the spring and diaphragm. Upon a withdrawing rotation of sleeve 28 and its assemblage from chamber 15, it is desirable that retainer 26 avoid electrical contact with housing portion 12. Consequently, bushing 27 is provided with an enlarged flange at its top end so that maximum sleeve withdrawal halts upon bushing 27 bearing against the housing and for this purpose it is convenient that the insulated members 27, 31 separate elements. The material constituting diaphragm 16 will be chosen to accommodate type of tluid that is being sensed. Switch it) has been shown as a device for responding to a drop in a fluid pressure system below a preselected value. In the same manner, the switch may be employed to indicate the rise of pressure above the preselected value. In this instance, the warning light will turn off above a critical pressure value. In the irst example, i.e., in sensing a pressure drop below a critical value, there is no current drain during normal operation of switch 10 except when a warning is provided. The current capacity of the switch circuit may be varied, for example by suitably selecting the material or diameter of spring 25 or by changing area of contact made by elements 17, 23. Although the switch has been described with respect to application to a boat, it is equally evident that it is of equal use in systems employed in land vehicles and aircraft.

It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A pressure sensing switch for making an electrical contact in response to a change of pressure of a fluid comprising, a frame having an upper and a lower portion, said frame portions having operatively engaging annular anges, a diaphragm clamped between said ilanges, an electrically conductive washer formed also clamped between said annular ilanges and having a seat extending into the lower part of said frame, an insulating body normally seated in said seat formed by said washer, said insulating body abutting against a first side of said diaphragm, means adapted to accommodate the variablepressure fluid in the upper part of said frame and against the second side of said diaphragm, an electrically-conductive and selectively preloaded spring located in the lower portion of said frame, the upper end of said compression spring acting against said insulating body and urging it towards said diaphragm, an electrically conductive member movable with said insulating body and in electric contact with said spring, said member forming the movable part of a normally open electric contact, said seat for said insulating body forming the fixed part of said electric contact, means securing the lower end of said spring relatively xed with respect to the lower frame portion and also for selectively preloading said spring and including a tubular member having an outer threaded portion engaging a threaded hole in said lower frame portion wherein said tubular member may be axially adjusted in either direction along the spring axis, said tubular member having a through bore, said threaded hole being located adjacent the lower end of said spring, the lower end of said tubular member extending exteriorly of said lower frame portion, a first insulator bushing extending part way into said tubular member bore from the interior side of said lower frame portion, said first bushing having a flange overlapping the upper end of said tubular member for limiting projection of said bushing into said tubular member bore, a second bushing having a flange overlapping the lower end of said tubular member for limiting the amount of projection of said second bushing into said tubular member bore, a conductive retainer resting on said first bushing, the lower end of said spring being seated on said retainer and urging same against said rst bushing, said retainer and bushings having aligned openings, a conductive member having an upper end overlapping said retainer, said conductive member extending through the aligned openings of said retainer and bushings and having a lower end projecting exteriorly of said lower frame portion for connection with one side of an electrical signal source the other side of which is connected to said electrical conductive washer, said conductive member making electrical contact with said spring and being electrically insulated from said frame by said bushings, a threaded surface on the lower end of said conductive member, a nut engaging said last-mentioned threaded surface and overlapping said second bushing flange and means for threadedly locking said tubular member in a desired position axially in either direction along said spring axis, said preloading assemblage being clamped together by drawing said nut up against said second bushing ange as said irst bushing flange is pulled against the upper end of said tubular member, said spring expands to move said insulating body towards said diaphragm to cause said movable conductive member to contact said conductive washer for closing the normally open switch when the pressure exerted by the preloaded spring against said diaphragm exceeds the pressure exerted by the uid on said diaphragm.

2. A pressure sensing switch for making an electrical contact in response to a change of pressure of a fluid comprising, an enclosed housing of electrical conducting material, a diaphragm supported in said housing and detining a pair of chambers on opposite sides of said diaphragm and in said housing, spring means in one chamber and having a first end adjustably xed with respect to said housing and the other end adapted to act upon one side of said diaphragm, the plane of said diaphragm being at an angle to the axis of said spring and the other side of said diaphragm being exposed to the other chamber, means for coupling the iuid into said other chamber wherein said spring imparting a preload against said diaphragm in opposition to the pressure exerted thereon by said fluid, and an electrical contact relatively fixed with respect to said housing portion and adapted to make electrical closed contact with respect to said spring upon movement of said spring in response to a fluid pressure of preselected value, means for selectively preloading said spring including a tubular member having an outer threaded portion engaging a threaded hole in said housing wherein said tubular member may be axially adjusted in either direction along the spring axis, said tubular member having a through bore, said threaded hole being located adjacent the first end of said spring, the lower end of said tubular member extending exteriorly of said housing, a rst insulator bushing extending part way into said tubular member bore from the interior side of said housing, a second insulator bushing extending part way into said tubular member bore from the exterior side of said housing, said second bushing having a ange overlapping the lower end of said tubular member for limiting the amount of projection of said second bushing into said tubular member bore, said first bushing having a ilange overlapping said tubular member for limiting its projection into said tubular member bore, a conductive retainer resting on said rst bushing, the iirst end of said spring being seated on said retainer and urging same against said rst bushing, said retainer and bushings having aligned openings, a conductive member having an upper end overlapping said retainer, said conductor member extending through the aligned openings of said retainer and bushing and having a lower end projecting exteriorly of said housing for connection with one side of an electrical signal source the other side of which is connected to said housing, said conductive member making electrical Contact with said spring and being electri' cally insulated from said housing of said bushings, the lower end of said conductive member having a threaded surface, a nut engaging said conductive member threaded surface and overlapping said second bushing ange, and means for threadedly locking said tubular member in a desired position axially in either direction along said spring axis, whereby the preloading assemblage is clamped together by drawing said nut up against said second bushing ange as said rst bushing flange is pulled up against the adjacent end of said tubular member.

References Cited in the le of this patent UNITED STATES PATENTS 2,698,887 Shaw Jan. 4, 1955 2,744,977 Lombard et al. May 8, 1956 2,783,324 Brown et al Feb. 26, 1957 2,898,418 Byam Aug. 4, 1959

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