US3786212A

US3786212A - Condition responsive control device with capacity for independent adjustment of control points

Info

Publication number: US3786212A
Application number: US00236732A
Authority: US
Inventors: E Weber
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-05-31
Filing date: 1972-03-21
Publication date: 1974-01-15
Anticipated expiration: 1991-01-15
Also published as: AU472992B2; FR2166854A5; CA966175A; DE2224026C2; NL168362C; CH553339A; JPS5219308B1; DE2224026A1; IT955906B; NL168362B; NL7207353A; GB1381654A; AU4264472A; BE784213A

Abstract

A control device wherein a pressure sensitive element displaceable by pressure variations, transmits linear motion to a balance plate. Stops associated with the balance plate define a pair of axes about which the balance plate alternately pivots. The device includes a single control such as a microswitch having a single actuator displaceable between first and second positions corresponding to mutually cancelling control modes. Pivotal movement of the balance plate about one axis effects movement of the actuator through the first position while pivotal movement about the other axis effects movement of the actuator through the second position. The pressures at which the respective positions are attained can be independently determined by adjustable springs acting on the balance plate and through the respective axes.

Description

United States Patent 1191 Weber Jan. 15, 1974 [54] CONDITION RESPONSIVE CONTROL 3,098,141 7/1963 Wintriss 200/153 W UX DEVICE W CAPACITY FOR 3,303,306 2/1967 Fischer et al. 200/83 S 3,390,242 6/1968 gg N q fgggi gfNlg 0F 3,182,150 5/1965 Smith 200/83 SA [76] Inventor: Ernesto Juan Weber, Lluvia 470, FOREIGN PATENTS OR APPLICATIONS State of the Federal District, 1,263,541 7/1960 France 200/153 T Mexico E J R S Primary xaminer cott v [22] Flled: 1972 Assistant ExaminerRobert A. Vanderhye 211 App] 23 732 Att0rneyArthur Schwartz 7 Related US. Application Data [63] Continuation-impart of Ser. No. 154,536, June 18, [57] ABSTRACT 1971 A control device wherem a pressure sensitive element displaceable by pressure variations, transmits linear [30] Foreign Application P i it D t motion to a balance plate. Stops associated with the May 31 1971 Mexico 44155 balance plate define a Pair axes about which the balance plate alternately pivots. The device includes a [52] CL H 200/83 R 200/83 S 200/153 T single control such as a microswitch having a single 337/323 actuator displaceable between first and second posi- 51 1111. C1. H0lh 35/34 ions Corresponding mutually cance'ling 58 Field of Search 200/153 T 83 R m0des- Pivma] "Ovemenl of balance Plate about 200/83 s 83 SA 83 J 82 R 82 5 one axis effects movement of the actuator through the Q 5 first position while pivotal movement about the other axis effects movement of the actuator through the sec- [56] References Cited 0nd position. The pressures at which the respective positions are attained can be independently deter- UNITED STATES PATENTS 1 mined by adjustable springs acting on the balance plate and through the respective axes.

3,210,486 10/1965 Holzer 200/81 R X 43 Claims, 9 Drawing Figures PATENTEDJAN 15 m4 3. 786, sum 1 OF 4 212 FIG. 1

PATENTEUJAN 15 m4 sum 2 OF 4 mzminm 15 m4 3786 212 sum 3 er 4 CONDITION RESPONSIVE CONTROL DEVICE WITH CAPACITY FOR INDEPENDENT ADJUSTMENT OF CONTROL POINTS CROSS REFERENCE TO RELATED APPLICATIONS This is a continuation-in-part of US. application Ser. No. 154,536 by Ernesto J. Weber, filed on June 18, 1971.

BACKGROUND AND OBJECTS OF THE INVENTION 1. Field of the Invention This invention relates to a control device, and, in par ticular, a control device in the form of a pressure switch. The device includes an expansible chamber having a pressure sensitive element, such as a diaphragm, displaceable by variations in pressure. The pressure sensitive element actuates a control means, such as a microswitch, to produce a control signal in response to the pressure variation.

In the present type of device, the pressure sensitive element is coupled to a balance means which in turn, is coupled to a pair of biasing means or springs which urge the balance means in a direction opposing expansion of the chamber. The resulting diaphragm displacement is transmitted to the balance means, causing the balance means to move against the force of the weaker spring. This movement is a pivotal movement about a first stop or abutment located opposite the weaker spring. The balance means is held against this stop by the heavier spring. The pivotal movement continues until the moving portion of the balance means adjacent the weaker spring engages a second stop. At this point, the balance means is at the midpoint of its overall movement, further movement about the first stop being prevented by the second stop. When pressure is sufficiently great to overcome the biasof the heavier spring, the balance means beings to pivot about the second stop until it reaches its extreme high pressure position.

As the pressure decreases from the extreme high pressure point, the balance means will, of course, again pivot about the second stop, under the bias of the heavier spring, but in the opposite rotational direction until the middle position is again reached. At the middle position, the balance means is restrained by the first stop from further pivotal movement about the second stop. When the pressure drops sufficiently, the balance means will again pivot about the first stop under the bias of the weaker spring. This movement continues until the balance means reaches its extreme low pressure position.

The type of movement described above, and apparatus for effecting the same, will hereinafter be referred to as alternating fulcrum movement and alternating fulcrum apparatus.

In many pressure switch applications, it is desirable to provide a pressure differential between two different modes of actuation, for example, an on mode and an off mode. The use of an alternating fulcrum device is ideal in this context for the movement of the balance means about one of the alternating fulcrums can control the on actuation ahd the movement about the other other fulcrum can control the off deactuation. Even more advantageous is the fact that the biasing means can be made adjustable to control the movement of the balance means and to concomitantly control the pressure values at which the switch is actuated or deactuated. Therefore, the use of an alternating fulcrum device having adjustable biasing means coupled to a balance means allows independent adjustment of the switch on and off points to practically any value in the overall operating range of the switch.

While the type of device contemplated has been and will be referred to as a pressure switch, it will be understood that the present invention can be equally well aapted to a vacuum responsive device, a temperature responsive device using a confined fluid, or a differential pressure responsive device.

2. Description of the Prior Art The use of an alternating fulcrum movement per se in a pressure switch is known in the art.

U.S. Pat. Nos. 2,284,940; 2,266,144; and 2,274,119 to A.E. Baak all disclose such devices. In these patents, as well as in all true alternating fulcrum devices, it is necessary that at least two stop or abutment means be disposed on opposite sides of the balance means from each other. The points of engagement of the stop means or abutments form the fulcrums or axes about which the balance means pivots. Since the biasing means must also be connected with at least one side of the balance means, it becomes a problem to make the lines of action of the spring forces pass through the fulcrums or axes. This is true because, in the prior art devices, both the biasing means and the stop means one side of the balance means will interfere with each other if located in the same path. It is important that the forces of each of the biasing means pass through their adjacent fulcrums, because, if they do not, both biasing means will influence the movement of the balance means about each fulcrum. Since the separate springs are intended to independently determine the different points of response, this influence is detrimetnal to the proper functioning of the device. The first abovementioned patent expresses the desirability of making the biasing force act through the fulcrum, but examina tion of the disclosures in all the above patents makes it clear that the result sought after has not been achieved. In all three patents, the spring force acts at a point offset from the adjacent fulcrum so that an undesirable, extraneous rotative force will always be exerted on the balance means.

In the first reference mentioned above, adjustment of the biasing means is made from the same side of the unit as that on which the pressure inlet is located. Clearly, in many situations, this could make adjustment difficult or impossible. The last two mentioned references above provide for adjustment from positions spaced from the pressure inlet, but this is accomplished only through complex lever, linkage or transmission systems which in turn account for large, bulky and complex units.

US. Pat. No. 2,766,349 to Hamburg also discloses an alternating fulcrum pressure switch. An important drawback here is that the springs of different strengths are not adjustable and thus independent adjustment of different settings is not possible. While it appears that, in an indirect manner, the biasing forces may be made to act through the pivot points of the balance means, the forces are transmitted through mechanical means which clearly will introduce substantial friction, and thus extraneous forces will also be a problem here. Also, in Hamburg, it is necessary to use two microswitches, one at each end of the balance means, to obtain a substantial differential between actuation points.

U.S. Pat. No. 3,210,486 to Holzer discloses an alternating fulcrum device, or more precisely, an alternating axis device. The arrangement is such that the biasing forces do not act on the axes at all times.

'U.S. Pat. No. 2,790,044 to Booth discloses another device, which, broadly speaking might be considered to disclose movement about two axes to effect switch actuation. Here the biasing means is non-adjustable and acts on the balance means at a location clearly remote from the pivoting axes.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a control device of the foregoing type of improved and simplified construction, embodying relatively few operating parts and which can be built at a relatively low cost with a very compact configuration.

It is a further object of the invention to provide a control device wherein at least two distinct control points can be made independently adjustable over a large range, and more particularly, a device which can provide such adjustability when coupled with a single microswitch, or similar control means, having a single actuator.

It is another object of the invention to provide an alternating fulcrum or alternating axis control device having a pair of adjustable biasing means which act independently from each other.

It is an additional object of the invention to provide an alternating fulcrum or alternating axis device wherein the lines of force of the adjustable biasing means act through the fulcrums or axes.

Another object is the provision of a connection and- /or linkage means between the balance means and the microswitch or control means, which linkage and/or connection means is simple, reliable and economical and which comprises relatively few parts.

A further object of the invention is the provision of a simple, inexpensive lost motion means between the balance means and microswitch or control means to compensate for different ranges of displacement of the balance means and of the actuator of the control means.

Another object is the provision of an alternating axis device wherein the axes nearly intersect at a pivotal set of stops, the effective connection point of the balance means to the control means being at a point on the balance means whereby the control means is not influenced by minute displacements of the balance means at the pivotal set of stops.

Yet another object is the provision of a control device having a piston and a diaphragm which are interconnected, and a means associated with the diaphragm for eliminating friction betwen the piston and its associated cylinder.

Other objects and advantages will be apparent from or pointed out in the following description and accompanying drawings.

SUMMARY OF THE INVENTION The present invention overcomes the difficulties found in the prior art devices by providing an adjustable biasing means whose lines of force act directly through each fulcrum or axis of the balance means. In one embodiment, this is accomplished by providing a balance means in the form of a beam with recessed portions at each end. Each recess provides additional surfaces on the balance means whereby the stop means and biasing means may be aligned with each other.

In another embodiment, the balance means takes the form of a plate which pivots about two alternating axes, each axis being defined by stops which are spaced from each other. With this arrangement, it is possible to locate the biasing means between the stops and yet position each biasing means so as to act directly on one axis. This latter arrangement has the advantage of providing much greater stability and reliability than can be obtained from a beam arrangement, and the added stability permits the use of compression coil springs as biasing means.

Compression springs have the advantage that they can be most readily positioned on the side of the balance plate opposite to the pressure sensing means and associated pressure inlet. Clearly, in most circumstances access to the switch will be easier from the side opposite the inlet. Thus, with compression springs, adjustments to the spring forces (and thus the response characteristics of the switch) can be made from the side opposite to the inlet. Also, when tension springs are used, mechanisms to permit rotation of the adjustment screws with respect to their associated springs are required. With the use of compression srings, no such mechanisms are required, since the springs themselves are free to rotate. The use of coil springs in cpmpression is made more practical by the addition of special spring guides to prevent buckling.

Another important feature of the present invention is the fact that the structural arrangement enables the use of a single, interchangeable, sensitive microswitch to obtain a large scale independent adjustment of control points. In all the prior art devices, it is necessary to use a plurality of microswitches coupled to opposite portions of the balance means for realization of the different actuating capabilities which can be derived from an alternating fulcrum movement. Nowhere in the prior art is it realized that an alternating fulcrum movement can be used in conjunction with the inherent differential between distinct actuator control positions (e.g., on, off positions) of a conventional, sensitive microswitch to obtain widely and independently variable control points in terms of pressure. In other words, the almost microscopic fixed differential inherent in the microswitch is effectively made adjustable over a very large range by the mechanism of the present invention. This is accomplished by providing a single actuator, such as a push button, extending from the microswitch casing and operatively connected to the balance means at a point between the two sets of stops exclusive of the pivotal set.

The above-described combination of a single microswitch, having a single actuating button with an alternating fulcrum device, is facilitated by interposing a resilient means between the balance plate and the microswitch. The microswitch actuating button displacement will be very small when compared with the displacement of the pressure sensitive element or balance means. To facilitate the reduction of this discrepancy, the resilient means is made sufficiently weak as to absorb some of the movement of the balance means during its normal stroke. Thus, the resilient means provides an extremely simple, inexpensive lost motion connection between the balance means and the control means which is particularly suitable for use with the present type of alternating fulcrum device. Any resilient means is subject to wear and this wear would normally change the response characteristics of the pressure switch. However, in an alternating fulcrum device, where on and off points are independently adjustable, any change in response characteristics can readily be compensated.

Also, the fact that the actuating means is effectively connected to the balance plate between the two sets of stops exclusive of the pivotal set prevents any substantial multiplication of vertical movement due to minute displacements of the balance plate at the pivot.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view, partly in side elevation and partly in section, of a device according to one embodiment of the invention.

FIG. 2 is an exploded perspective view of most of the elements of the device of FIG. 1, certain elements being shown in section.

FIG. 3 is another exploded perspective view of the device of FIG. 1 including elements not shown in FIG. 2.

FIGS. 4, 5 and 6 are fragmentary sectional views of the device shown in FIG. 1, these figures illustrating various displaceable elements at different positions.

FIG. 7 is a fragmentary exploded perspective view of a modification to the embodiment of FIG. 1.

FIG. 8 is a fragmentary sectional view of a modification to the embodiment of FIG. 1.

FIG. 9 is a view partly in section and partly in side elevation of a device according to another embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS Structural Description of Embodiment of FIGS. l-6

Referring to FIGS. 1-6, in the specifically illustrated embodiment of the invention, therexis shown a cylindrical housing 1 having a bottom end wall member 2 forming one wall of a sensing chamber 4. Another wall of the sensing chamber 4 is defined by a pressure sensing element herein illustrated as a diaphragm 6. The diaphragm in effect divides the housing into two chambers, namely, aforementioned lower sensing chamber 4, and upper control chamber 5. The periphery of the diaphragm is held in place, on one side, by a cylinder ring 8 secured to the housing 1 and, on the other side, by an O-ring 10 which is pressed against the diaphragm by the bottom end wall member 2. The member 2 in turn, is held in place in the housing by a snap ring 12.

While the pressure sensing means illustrated here takes the form of a diaphragm, any other suitable means such as a bellows or piston may be used.

A connection means 14, threaded to accommodate an appropriate conduit or fitting, communicates with a central passage 16 in the bottom end wall member 2. The central passage 16, in turn, communicates with the sensing chamber 4.

The upper surface of the diaphragm 6 engages a piston 18 which moves within the cylinder ring 8. Abutment l5 prevents the piston from falling out of its cylinder and functions as a lower limit to downward movement. The piston 18 is centered in the diaphragm by an annular convolution 20 on the diaphragm formed by pressure when the device is in operation. The convolution 20 has a mean diameter slightly greater than the diameter of the piston and is shaped by pressure so as to engage the peripheral edge portions of the piston to prevent lateral movement thereof. The advantage of such a piston centering arrangement is that it affords a simple means for avoiding friction between the piston and the cylinder ring.

The housing includes an intermediate wall portion 22 which serves as an upper abutment to secure the cylinder 8 in place within the housing 1. In the center of the intermediate wall 22, is a bore 24 passing therethrough and having a counterbore 25 at the upper surface of the wall 22. A pin 26 stepped in two diameters is disposed in the bore, larger diameter portion 27 being disposed within the counterbore 25. At the upper, large diameter portion 27 is a recess 28 which carries a ball 29. The ball 29 defines a pivot about which the piston is free to rotate, and this freedom of rotation facilitates formation of the convolution 20 by pressure.

Adjacent the upper surface of the intermediate wall 22 there is disposed a shim 30 of spring-likg material having a symmetrical spider-like shape. The shim includes an annular outerrim 31, symmetrically arranged spokes 32 and a perforated inner hub 33. The outer rim 31 of the shim 30 is held in place against the intermediate wall portion 22 by a lower space member 38, but the inner hub 33 is free to move vertically along with the pin due to the resiliency of the shim material and the reduced resistance resulting from the spoked configuration. Perforated hub 33 is suitably and firmly attached to a recessed portion 45 of a balance plate 42, located above the shim.

The balance plate 42 has a generally disc-like configuration with a lower surface 43 and an upper surface 44. The recess 45 has a central ball receiving part with a lower concave portion 34 and an upper convex portion 35. The lower concave portion engages the ball 29 of pin 26. At points on the balance plate radially spaced from each other and near the periphery thereof are located three balls or

spherical members

46, 47 and 48.

Balls

46 and 47 are smaller than ball 48. Ball 46 protrudes downwardly from the balance plate, and ball 47 protrudes upwardly. Preferably, the balls are so located with respect to each other as to form the points of an equilateral triangle. The balls may be secured within holes in the balance plate by staking or, alternatively, may be formed integrally with the balance plate. The open spaces between the spokes 32 of the shim 30 are aligned with the three balls so as to permit a direct contact thereof with the intermediate wall.

Above the balance plate is a ball stop plate 50 held in place by lower spacer member 38. Also disposed above the balance plate 42 are a pair of coil springs 52,53 which are connected at their lowermost ends to spring rests 54,55. The spring rests include

annular shoulders

56,57 and downwardly projecting

fingers

58,59 at the lower portions thereof. These

fingers

58, 59 engage

complementary depressions

60,61 in the balance plate to bias the plate downwardly.

The three

balls

46, 47, 48 are arranged on the balance plate so as to define a pair of axes A,B (see FIG. 2) about which the balance plate alternately pivots. Each axis is defined by two points, each point being a point of engagement of one ball with an adjacent sur face. The balls are arranged so that the largest ball 48 i is common to both axes, locating one of the two points defining each axis. Ball 48 and the adjacent surfaces engaged thereby are referred to as the pivotal set of stop means.

The ball stop plate 50 includes a central opening with curved cut out

portions

62,63 for allowing the passage of the spring rests 54,55 therethrough. The sectional view of FIG. 1 is taken through these

portions

62,63 so that the largest open area of the plate 50 is illustrated. The orientation of the balance plate 42 with respect to the ball stop plate 50 is such that the

balls

46,47 and 48 are not aligned with the cut out

portions

62 and 63. Thus, ball 47 will come into contact with the ball stop plate 50 upon an upward pivoting movement of the balance plate 42. The largest ball 48 is of sufficient diameter to prevent any significant vertical movement thereof between the ball stop plate 50 and the intermediate wall 22.

The upper portion of the housing includes a top closure 66 having a pair of threaded

openings

68,69 therein. A pair of threaded adjustment screws 70,71 cooperate with these openings and with the coil springs 52,53 for adjusting the compression thereof. The adjustment screws each include a

tool engaging means

72,73 whereby each screw can be rotated to vary the vertical position thereof to adjust the associated spring. Each adjustment screw includes a recess 74,75 at the bottom thereof, each recess receiving the uppermost portion of one of the coil springs 52,53. Each of the two adjustment screws includes an

annular rim portion

76,77, one rim portion 77 being at the uppermost end of its respective adjustment screw 71, the other rim portion 76 being located below the uppermost portion of its adjustment screw 70. The spacing between the two

adjustment screws

70,71 is such that the rim portions of each are mutually overlapping, the rim portion 77 being above the rim portion 76. By this arrangement, it is impossible to adjust the screw 71 to a position below that of screw 70 or to adjust screw 70 to a position higher than screw 71. As the adjustment screw 70 is moved to a relatively lower position, it is clear that the compressive force on its respective coil spring 52 will be increased. Since the arrangement of the

respective rims

76, 77 is such that the relative position of the adjustment screw 70 is always lower than or equal to that of adjustment screw 71, spring 52, associated with screw 70, is to be considered the high pressure spring in relation to the low pressure spring 53 associated with the adjustment screw 75.

Secured above the top closure 66 is a control means 78, preferably in the form of an electric, single pole, double throw, low differential, low force, two-position spring-return microswitch. Any suitable electrical switch or fluid controlling valve of the spring-return or toggle type could be used equally well, as long as there are provided two distinct actuation positions separated by a displacement differential, the positions corresponding to two distinct mutually cancelling control modes. By way of example only, and for the sake of convenience, these two positions and their respective control modes are referred to herein as the actuation or on position and the deactuation or off positions.

The microswitch here includes a casing. 79 from which extends an actuating button 82, having one position at which the switch is actuated (i.e., the on position) and another, different position at which the switch is deactuated (i.e., the off position), so that an inherent displacement differential exists between the on and off positions.

The microswitch is fastened to the housing 1 by an adjustable mount which can be used to vary the vertical position of the microswitch with respect to the housing 1.

In the illustrated embodiments, an actuating post 84 between the actuating button 82 and the balance plate 42 transmits only the linear vertical displacements of the balance means to the actuating button. A resilient means 86 is also interposed between the actuating button and the balance plate. This resilient means will be referred to as the amplification spring. In the embodiments of FIGS. 1-6, the amplification spring 86 is attached to the upper surface 44 of the balance plate 42 and is connected to the lower portion of the actuating post 84. The amplification spring 86 is made sufficiently weak so as to serve as a lost motion connecting means, reducing the amount of motion transmitted from the balance plate 42 to the actuation button 82 during the normal stroke of the balance plate and diaphragm. This reduction of transmitted balance plate motion can be said to amplify the relative inherent displacement differential of the microswitch.

In an actual working model of a device according to the present invention, the piston moves through a stroke of approximately 0.006 inches. At the same time the range of the microswitch button between on and off points is about 0.0005 inches to 0.0015 inches. Here the amplification spring provides a simple and inexpensive means to compensate for these differences in displacement ranges.

The effective point of connection of the actuating post 84 to the balance plate is located approximately midway on a straight line between the two

balls

46 and 47. Although, as illustrated, the actuating post 84 first connects with the amplification spring which, in turn, is connected with the balance plate 42, the post 84 may alternatively be directly attached to the balance plate (assuming the amplification spring has a different location). In the embodiments illustrated, the effective point of connection of the actuating post 84 with the balance means is the point at which the post 84 would engage the balance means if extended downwardly past the amplification spring. It is desirable to place the effective point of connection as close as possible to the midpoint of the line between

balls

46 and 47. This in turn, assures independence of actuating post displacements with respect to minute balance plate movements at the pivotal set of stops where both axes intersect ball 48. The aforesaid line between the

balls

46 and 47 can be considered as a third axis (in addition to axes A and B) about which the balance plate pivots during minute displacements of the balance means at ball 48.

The provision of, on the amplification spring 86, a portion 87 which extends away from the largest ball 48 (and thus away from the region where the two axes nearly intersect), facilitates the placement of the effective point of connection of the actuating means near the midpoint of the line between

balls

46 and 47.

The possibility exists, with the use of certain types of compression springs 52,53, that they may have a tendency to buckle causing a cocking or rotation of the spring rests 54 and 55. This undesirable occurrence can be eliminated by providing

elongated guide members

90 and 91 surrounding and affixed to the spring rests 54,55. The guide member 90 is secured at one end to the left hand spring rest (FIGS. I6) and at the other end to the part of the housing shown at the right. A similar but converse arrangement exists for the guide member 91. This latter guide member is secured to the right hand spring rest 55 and the left hand portion of the housing.

When the spring rests move vertically due to balance plate displacement, the guide members rotate so that the ends nearest the spring rests move substantially vertically while the other ends remain secured in the housing. Although, strictly speaking, the movement is arcuate, this is minimized by the fact that the elongation of the

guide members

90,91 is made as great as possible.

Both

guide members

90,91 and the ball stop plate 50 are secured in place between an upper spacer 92 and the aforementioned lower spacer 38. The ends of the guide members can rotate inside of elongated cavities formed by

recesses

117 and 118 in the upper spacer and the top surface of the intermediate wall 22. Alternatively, the guides may be fastened to the stationary housing by means of suitable flexible members.

A transparent plastic cover 94 is attached to the top closure 66 to completely enclose the microswitch 78 and adjustment screws 70 and 71 to protect the same from dirt, dust or any other harmful materials in the surrounding environment.

An opening 95 through the housing 1 and upper spacer 92 together with an opening 119 in the top closure 66 serves the purpose of providing a passage for the necessary connecting cables. Opening 95 is suitably threaded for connection with a conduit.

Operation of Embodiment of FIGS. 1-6

The operation of the device illustrated in FIGS. 1-3 will be described below, with reference being made to FIGS. 4, 5 and 6 showing various displaceable elements in different sequential positions.

FIG. 4 illustrates the extreme low pressure position of the diaphragm and balance plate. In this position the

balls

46 and 48 are held at rest against the intermediate wall 22 by the force of the coil springs 52,53. Ball 47 is at an intermediate position and piston 18 rests on abutment 15. As pressure in chamber 4 increases, the diaphragm and piston will be displaced upwardly. This upward displacement will be transmitted to the piston 18 and thence to pin 26. The ball 29 transmits the motion of the pin 26 past the inner hub 33 of the flexible shim 30 and to the concave portion 34 of the balance plate 42. The balance plate will first begin to move against the force of the weaker of the two coil springs, namely, spring 53, lifting ball 47. Meanwhile, the high pressure spring 52 will maintain the ball 46 firmly in place against the intermediate wall. The above described movement of the balance plate, therefore, is a counterclockwise pivotal movement about axis A (defined by the points of contact of

balls

46 and 48 with the intermediate wall 22).

Pivotal movement of the balance plate about the axis A will continue until the upper surface of the ball 47 comes into contact with the ball stop plate 50 to restrain further upward movement. At this point the balance plate is disposed in the middle position as illustrated in FIG. 5. The balance plate will remain in this position until the pressure in the chamber 4 has increased to an amount sufficient to overcome the bias of the high pressure spring 52. At this point, the ball 46 is lifted from the intermediate wall and moves upwardly. To permit such movement, the balance plate pivots in a clockwise direction about the axis B (defined by the points of contact of

balls

47 and 48 with the ball stop plate 50). Pivotal movement of the balance plate about axis B will continue until the extreme high pressure position shown in FIG. 6 is reached.

Upon decrease in pressure, the sequence of operations is precisely the reverse of that described above. With reference to FIGS. 5 and 6 the pivotal movement about axis B from the high pressure position of FIG. 6 to the middle position of FIG. 5, as pressure decreases, is in a counterclockwise direction. After a decrease in pressure to a point at which the weaker spring 53 is able to overcome the upward force on the diaphragm, the balance plate will begin to return from the middle position of FIG. 5 toward the low pressure position of FIG. 4, pivoting in a clockwise direction about the axis A.

It will be understood that, at all times when the balance plate pivots about the axis A, the line of force of the high pressure spring 52 will be acting directly through that axis, so that the high pressure spring is rendered ineffective, exerting no influence on the pivotal movement of the balance plate. Likewise, during movement of the balance plate about the axis B, the low pressure spring 53 acts directly through that axis and is rendered ineffective, exerting no influence on the pivotal movement.

The above described alternate pivotal movements of the balance plate effect only a linear displacement of the actuating post 84. The motion is transmitted from the balance plate to the actuating post 84 via the amplification spring 86 which serves as a lost motion connection. The linear movement of the actuating post is transmitted to the actuating button 82 of the microswitch 78 for actuation and deactuation thereof.

As discussed above, there is an inherent displacement differential between the position of the actuating button at which actuation of the microswitch is effectuated and the position at which deactuation is effectuated. This inherent differential between on and off points is common in known microswitches and other similar control means.

In the device of the present invention, the vertical position of the microswitch 78 with respect to the housing 1 is adjusted so that the middle position of the balance means, as illustrated in FIG. 5, corresponds to the middle position in the inherent displacement differential of the microswitch. In other words, with the balance plate in its middle position, the microswitch actuating button is midway between the actuation and deactuation points.

By way of example only, it will be assumed that the deactuation or off point of the microswitch corresponds to the vertically lower actuation button position in relation to the on point. As described above, assuming the balance plate to be in the low pressure position and the microswitch in the off position, as pressure increases in the chamber 4, the balance plate 42 pivots about the axis A until reaching the middle position. With sufficient additional increase in pressure, the balance plate then begins to pivot about axis B. During this latter pivotal movement, the post 84 will cause the button 82 to pass through the actuating position moving the switch to the on position.

As also described above, a pressure decrease causes the balance plate to move back to the middle position by pivoting about axis B. Then, after sufficient decrease in pressure, the balance plate begins to pivot about axis A toward the low pressure position. During this latter pivotal movement about axis A, post 84 causes the button 82 to pass through the deactuation point moving the switch to the off position.

It will be understood that the values of pressure at which the microswitch is moved into the on and off positions are determined by the adjustments to the biasing forces of the

springs

52,53. To obtain a very wide pressure differential between on and off points, the high pressure spring 52 is adjusted to exert a very high biasing force. This is accomplished by moving the adjusting screw 70 to a relatively low position. At the same time, the low pressure spring 53 is adjusted to exert a relatively weak biasing force by moving the adjusting screw 71 to a relatively high position. With such an adjustment, assuming all the elements to be in their extreme low pressure positions, a very small increase in pressure causes the balance plate and microswitch button to move into their middle positions at a very low pressure. The balance plate and switch button remain in this middle position over a large range of pressure increases until the pressure reaches a value near the maximum. At this high pressure, the force of the high pressure spring will finally be overcome to actuate the microswitch.

With only a small pressure drop, the balance plate and switch button again return to their middle positions but the microswitch remains in the on condition. After a large pressure drop to a point near the minimum pressure, the balance plate begins to pivot from its intermediate position toward its low pressure position for deactuating the microswitch to the off condition.

It will be clear that a setting of the adjustment screws, whereby little difference exists between the bias on the low pressure and high pressure springs, creates a condition wherein the balance plate remains in the intermediate position only during a very small pressure change. With this condition, therefore, the pressure differential between on and off positions of the microswitch is likewise very small. Also, it will be clear that, by adjustment of the biasing force on the springs, the high pressure on point and low pressure off point can be adjusted to practically any point within the overall range of operation of the device.

Modification According to FIG. 7

FIG. 7 shows an alternative embodiment wherein the ball stops, rather than being secured to the balance plate, are located separately therefrom. Whereas, in the previously discussed embodiment, the complete stop means included the combination of the three balls on the balance plate, plus the lower, intermediate wall 22, plus the upper, ball stop plate 50; the complete stop means in the present embodiment includes the balance plate itself plus a set of balls adjacent both the upper and lower faces of the balance plate. Whereas in the previously described embodiment, movement of the balance means caused the balls thereon to alternately come into contact with the intermediate wall and ball stop plate, in the arrangement of FIG. 7, the balance plate itself comes into contact with stationary balls disposed on either side thereof. In the embodiment according to FIG. 7, elements which are substantially identical with the corresponding elements in FIGS. 1-6, are indicated by the same reference numerals. It is to be noted that, in FIG. 7, the wall 22 is shown as a separate part rather than as an element which is integrally formed with the housing, as in the previously described embodiment.

In FIG. 7, a set of three balls or

spherical members

101, 102 and 103 are located in corresponding holes of a ball guide 108. The balls are held in place both by the ball guide 108 and the intermediate wall 22 located therebelow.

Balls

101, 102 and 103 together with guide 108 are disposed below the shim 30 and balance plate 42. When the balance plate is in its extreme low pressure position, it will rest against all three

balls

101, 102 and 103.

Disposed above the balance plate are two additional balls or spherical members 110 and 111 located in holes in an upper ball guide 114. Directly above the guide 114 is the ball stop plate 50. Both the upper ball guide 114 and ball stop plate 50 are effective to hold balls 110 and 111 in their proper positions. The upper ball guide 114 includes cut out portions 115 and 116 substantially identical to, and aligned with, the corresponding cut out

portions

62,63 of the ball stop plate 50. These cut out portions permit passage of the spring rests 54,55 therethrough so that the

fingers

58,59 thereof may engage

depressions

60,61 of the balance plate 42. The balls 111 and 102 are aligned vertically with each other and are so spaced from each other as to preclude any substantial vertical movement of the balance plate 42 therebetween. The function of the balls 111 and 102, together, is analogous to that of ball 48 in the previously described embodiment. Each of the alternating axes, shown as A and B in FIG. 7, pass through the vertical line between balls 102 and 111.

Ball 101 serves merely as a stop or rest for the balance plate 42 when it is in its low pressure position. Ball 103 also serves this purpose, but, in addition, also serves to partially define the axis A about which the balance plate pivots during the initial stroke of the diaphragm. The axis A is fully defined by the points of engagement of the

balls

102 and 103 with the balance plate. The fact that the shim 30 has spokes 32 between the outer rim 31 and hub 33 permits the balls 10], 102 and 103 to protrude through the open spaces between the spokes and engage the balance plate.

The pivotal axis B is defined by the points of contact of balls 110 and 111 with the upper surface 44 of the balance plate 42. Ball 111 is larger in diameter than ball 110 and it may continuously engage the balance plate at all times (but it is also possible that a very small clearance may, at times, exist).

Operation of Modification According to FIG. 7

In operation, assuming that the balance plate is at its extreme low pressure position and is held against

balls

101, 102 and 103 by the force of

springs

52,53, an increase in pressure will cause the balance plate 42 to be lifted against the bias of the low pressure spring 53. The balance plate 42 will move vertically upwardly away from ball 101 while pivoting about the axis A. This movement continues until the upper surface of the balance plate comes into contact with ball 110, which is vertically aligned with ball 101. At this point further pivotal movement about the axis A is prevented. With a sufficient additional increase in pressure to overcome the force of high pressure spring 52, pivotal movement about the axis B will commence. This movement will continue until the extreme high pressure position is reached. Movement from the high pressure position to the low pressure position upon decrease of pressure is precisely the reverse of that described above.

In the embodiment of FIG. 7, the operation of remaining elements is the same as that of the corresponding elements of the embodiment of FIGS. 16. Modification According to FIG. 8

FIG. 8 shows a modification to the balance plate and ball arrangement of FIGS. 1-6. Rather than providing a single ball 48 staked into the balance plate so as to extend from both the top and bottom surfaces thereof,

balls

120 and 121 are provided on either side of a simple chambered hole 124.

The use of balls, as elements .of the complete stop means in all .of the above-described embodiments, is highly advantageous, since balls can be easily manufactured to very close tolerances. This is important here, where the displacements involved are very small. Also, the fact that metal balls can easily be hardened is important where, as here, they will be subjected to considerable wear.

Embodiment According to FIG. 9

FIG. 9 illustrates an additional embodiment of the present invention utilizing a beam 150 in place of the balance means 42 of the previously described embodiments. Here, tension springs 152, 153 are used in place of the compression springs 52,53 of the other embodiments. The same type of microswitch 78 and actuating button 82 therefor are used with this embodiment. As in the embodiments of FIGS. l-8, a pressure connection 14 communicates with a chamber 4 defined by a bottom end wall 2 and a diaphragm 6. The diaphragm is attached to a piston 18 which in turn is connected to an elongated vertical rod 155 engaging the central portion of the balance beam 150. Each end of the balance beam includes recessed

portions

158 and 159, each recessed portion being effective to provide a pair of downwardly facing

surfaces

160 and 162, 163 anc 165 at its respective end.

Tension coil springs

152 and 153 are connected near the ends of the balance beam adjacent the lowermost of the downwardly facing surfaces 162,165 at each end. The uppermost of the downwardly facing surfaces 160,163 are adapted to engage with stop means 168,169 secured to the housing.

Tension spring 153 is adjusted to be the low pressure spring and tension spring 152 is adjusted to be the high pressure spring. The arrangement is analogous to that of compression springs 52 and 53 of the embodiments previously described. An additional stop 171 is located on the side of the balance beam to which low pressure spring 153 is attached and is positioned to engage an upwardly facing top surface 173 on the balance beam. The arrangement of the springs and stops is such that, on each end of the balance beam, the line of force of the respective tension spring coincides with the point or points of contact of the respective stop or stops with the corresponding surface or surfaces of engagement on the balance beam.

In the same manner as the balls and their respective surfaces of contact formed points defining the alternating axes of the embodiments of FIGS. 1-8, the points of contact of the

stops

168 and 171 with the

surfaces

160 and 173 define the fulcrum points about which the balance beam 150 alternately pivots.

Operation of Embodiment of FIG. 9

The operation of the device of FIG. 9 is as follows.

Assuming the diaphragm 6 is in its extreme low pressure position, the downwardly facing

surfaces

160 and 163 will rest against

stops

168 and 169. As pressure increases and the diaphragm moves upwardly, surface 163 of the balance beam will be lifted off stop 169 against the resistance of the low pressure spring 153. At the same time the surface 160 will be held against stop 168 by the bias of high pressure spring 152 so that the balance beam pivots about the fulcrum defined by the point of contact of surface 160 and stop 168. This pivotal movement continues until the surface 173 engages the stop 171, at which point the balance beam is in its middle position. When the pressure increases sufficiently to overcome the tension of high pressure spring 152, the balance beam will begin to pivot about the fulcrum defined by the point of contact of stop 171 and surface 173. This pivoting movement continues until the high pressure position is reached. From this position the reverse alternating fulcrum movement takes place as the pressure decreases and the balance beam returns toward the low pressure position illustrated in FIG. 9.

It will be appreciated that the

stops

168 and 171 define the fulcrum points for the alternating pivotal movement of the balance beam. It will be further appreciated that these fulcrum points are aligned with the line of force of the adjacent tension spring. In this way, the spring adjacent a given fulcrum is rendered completely ineffective during rotation of the balance beam about that fulcrum. Therefore, similarly to the situation in the other embodiments, the

individual springs

152 and 153 operate completely independently of each other.

It will be understood that in the embodiment of FIG. 9, the operation of the microswitch with respect to the movement of the balance beam is identical to the operation thereof with respect to the movement of the balance plate 42 in the other embodiments. Thus, the device illustrated in FIG. 9 possesses the same capabilities of full-scale independent pressure differential and pressure range adjustment.

Overpressure Protection In none of the embodiments of the present invention, has there been illustrated or described a stop or abutment to restrain the pivotal movement of the balance means as it approaches its extreme high pressure position. It is intended that the position at which piston 18 contacts the intermediate wall 22 is to be considered the extreme high pressure position. Thus, in the event that the device is subjected to overpressures, the piston 18 and wall 22 will be able to withstand the forces thereof. If, on the other hand, a stop means associated with the balance means were to define the high pressure position, a significant overpressure in the chamber 4 could result in serious damage to the balance means.

In the embodiment of FIG. 2 this possibility of damage is prevented by having ball 46 protrude downwardly, leaving sufficient space between the balance plate and stop plate 50. In the embodiment of FIG. 7, the same result is obtained by the absence of a ball above the balance plate at the left hand, high pressure side. In FIG. 9, the override protection is obtained by the absence of a stop above the balance beam near the upper high pressure side.

Fixed Differential It is possible to convert the pressure switch of the present invention to operate as a fixed differential device. In such a device the displacement difference between the on and off points is relatively constant but the overall pressure range may be adjustable.

In the embodiments of FIGS. 1-8 this is accomplished by elimination of the low pressure spring 53, its associated adjustment screw, spring rest and guide. With such an arrangement, a negligible pressure will cause the balance plate to move into the middle position of FIG. 5. This constitutes the low pressure position, and any substantial variations in pressure will cause the balance plate to pivot about the axis B. The position of the microswitch is adjusted so that both the actuation and deactuation to and from the on and off points takes place entirely during the pivotal movement of the balance plate about axis B.

The same result is obtained in the device of FIG. 9 by eliminating the low pressure spring 153 and its associated adjusting screw. Here actuation and deactuation takes place during the pivotal movement about stop 171.

While throughout the above description words such as vertical", upper, "lower, upwardly, downwardly, right and left have been used, it will be understood that these terms are used only to describe relative relationships and are not intended to be limiting. It will also be understood that those skilled in the art may make many changes and modifications to the above-described embodiments of the present invention without departing from the spirit and scope thereof.

What is claimed is:

l. A control device comprising:

a. a housing;

b. a chamber in said housing;

c. a sensing means defining a wall of said chamber, said sensing means being displaceable through a stroke;

d. a balance means having first and second sides, said sensing means being operatively coupled to said balance means;

e. stop means associated with both said first and second sides of said balance means to define first and second axes about which said balance means pivots;

f. a pair of biasing means, at least one of which being adjustable and each having a line of force acting on said balance means, said biasing means being positioned with respect to said balance means such that the line of force of one of said pair passes through said first axis at all positions of said balance means and the line of force of the other of said pair passes through said second axis at all positions of said balance means;

g. a control means operatively coupled to said balance means;

h. whereby displacement of said sensing means through one part of its stroke effects pivoting of said balance means about said first axis and displacement of said sensing means through another part of its stroke effects pivoting of said balance means about said second axis.

2. A control device as defined in claim 1 wherein both biasing means of said pair are adjustable.

3. A control device as defined in claim 1 wherein:

a. said balance means is a balance plate;

b. said stop means includes a first portion and a second portion;

0. said stop means of said first portion includes a plurality of stops spaced apart from each other to define said first axis; and

d. said stop means of said second portion includes a plurality of stops spaced apart from each other to define said second axis.

4. A control device as defined in claim 3 wherein:

a. said first portion of said stop means is associated with said first side of said balance plate; and

b. said second portion of said stop means is associated with said second side of said balance plate.

5. A control device as defined in claim 1 wherein said 10 control means is a microswitch.

LII

6. A control device as defined in claim 5 wherein said microswitch is a single pole, double throw microswitch.

7. A control device as defined in claim 1 wherein:

a. said housing has first and second ends;

b. an inlet means communicates with said chamber, said inlet means being disposed in said first end; and

c. an adjusting means is disposed at said second end and is accessible from the exterior of said housing.

8. A control device as defined in claim 1 wherein each of said biasing means is elongated, the longitudinal axis of one of said biasing means passing through said first axis, the longitudinal axis of the other of said biasing means passing through said second axis.

9. A control device as defined in claim 1 wherein said stop means include:

a. a plate disposed in said housing above said balance means;

b. a wall disposed in said housing below said balance means;

c. a plurality of protrusions extending from both said first and said second sides of said balance means, said protrusions from said first side being adapted to engage said wall, said protrusions from said second side being adapted to engage said plate.

10. A control device as defined in claim 9 wherein said protrusions are formed by a plurality of spherical members, some of which have a first part extending from said first side of said balance means and others of which have a second part extending from said second side of said balance means.

11. A control device as defined in claim 10 wherein said balance means includes a plurality of holes in which said spherical members are affixed, whereby parts of said spherical members extend outwardly from said balance means.

said stop means include:

a. a first set of protrusions disposed in said housing apart from and below said balance means, said first set being adapted to engage said first side of said balance means; and

b. a second set of protrusions disposed in said housing apart from and above said balance means, said second set being adapted to engage said second side of said balance means.

14. A control device as defined in claim 13 wherein said protrusions are formed by spherical members.

15. A control device comprising:

a. a hollow housing;

b. a sensing means displaceable through a stroke, said sensing means dividing said housing into a sensing chamber and a control chamber;

c. a balance means in said control chamber operatively connected to said sensing means;

d. a plurality of stop means co-operating with said balance means to define a pair of axes about which said balance means pivots;

e. a pair of adjustable biasing means coupled with said balance means, said biasing means being adjusted to exert different biasing forces on said balance means, whereby movement of said sensing means through one part of its stroke effects pivoting of said balance means about one axis, and movement of said sensing means through another part of its stroke effects pivoting of said balance means about the other axis; a single control means associated with said housing, said control means having a casing means and a single displaceable actuator extending outside said casing means, said actuator being operatively connected to said balance means; and

g. said control means having a first control mode at a first position of said actuator and a second control mode at a second position of said actuator, whereby pivoting of said balance means about one of said axes effects movement of said actuator through said first position and pivoting of said balance means about the other of said axes effects movement of said actuator through said second position so that adjustment of said biasing means effects adjustment of said control modes.

16. A control device as defined in claim 15 wherein:

a. said balance means includes first and second sides;

and

b. said stop means are associated with said first and second sides.

17. A control device as defined in claim 16 wherein:

a. said balance means is a balance plate;

b. said stop means include a first portion and a second portion;

c. said stop means of said first portion include a plurality of stops spaced apart from each other to define said first axis; and

d. said stop means of said second portion include a plurality of stops spaced apart from each other to define said second axis.

18. A control device as defined in claim 17 wherein:

19. A control device as defined in claim 15 wherein said control means is a microswitch.

20. A control device as defined in claim 15 wherein said first control mode is an actuation mode'and said second control mode is a deactuation mode.

21. A control device as defined in claim 15 wherein said actuator is operatively connected to said balance means by an actuating post and a resilient means, said resilient means effecting a lost motion connection between said balance means and said control means.

22. A control device comprising:

A. a housing;

b. a chamber in said housing;

0. a sensing means defining a wall of said chamber, said sensing means being moveable through a stroke;

d. a balance plate, said sensing means being coupled to said balance plate;

e. stop means cooperating with said balance plate to define first, second and third axes, said stop means including a low pressure part, a high pressure part and a pivotal part, said first axis passing through said low pressure part and said pivotal part of said stop means said second axis passing through said high pressure part and said pivotal part of said stop means, said third axis passing through said high pressure part and said low pressure part, said pivotal part of said stop means being spaced from said third axis;

f. a pair of biasing means, at least one of which being adjustable, operatively coupled to said balance plate and adjusted to exert different biases, whereby movement of said sensing means through one portion of its stroke effects pivoting of said balance plate about said first axis and movement of said sensing means through another portion of its stroke effects pivoting of said balance plate about said second axis;

g. a control means associated with said housing, said control means having an actuation means effectively connected to said balance plate approximately on said third axis, whereby small displacements of said balance plate at said pivotal part of said stop means are not transmitted to said actuation means.

23. A control device as defined in claim 22 wherein:

a. said actuation means includes a resilient means attached to said balance plate;

b. said actuation means further includes an actuating post between said resilient means and said control means; and

c. said resilient means includes an extension thereon which is directed away from said pivotal part of said stop means and toward said midpoint.

24. A control device comprising:

a. a housing;

b. a chamber in said housing;

c. a sensing means displaceable through a stroke,

which means defines a wall of said chamber;

d. a balance beam means having first and second ends;

e. a recess in said balance beam means in the region of at least one of said ends;

f. a plurality of stop means co-operating with said balance beam means, at least one of said stop means co-operating with said recess;

g. said stop means defining first and second fulcrums about which said balance beam means pivots;

h. a pair of biasing means at least one which being adjustable and each having lines of force acting on said balance beam means, the line of force of one of said pairs passing through said first fulcrum and the line of force of the other of said pairs passing through said second fulcrum;

i. control means operatively coupled to said balance beam means;

j. whereby displacement of said sensing means through one portion of its stroke effects pivoting of said balance beam means about said first fulcrum and displacement of said sensing means through another portion of its stroke effects pivoting of said balance beam means about said second fulcrum.

25. A control device as defined in claim 24 wherein both biasing means of said pair are adjustable.

26. A control device comprising:

a. a housing;

b. a chamber in said housing;

c. a displaceable sensing means defining a wall of said chamber;

(1. a balance means having first and second sides, said sensing means being operatively coupled to said balance means;

f. a pair of adjustable biasing means opposing displacement of said sensing means in one direction;

g. a pair of rotatable screw means, each of said rotatable screw means being associated with one of said biasing means for adjusting the bias thereof;

h. said pair of rotatable screw means having mutually overlapping portions thereon;

i. a control means operatively coupled to said balance means;

j. whereby displacement of said sensing means through one part of its stroke effects pivoting of said balance means about said first axis and displacement of said sensing means through another part of its stroke effects pivoting of said balance means about said second axis.

27. A control device comprising:

a. a housing;

b. a chamber in said housing;

c. a displaceable diaphragm means defining a wall of said chamber;

d. a biasing means opposing displacement of said diaphragm means in one direction;

e. said diaphragm means engaging a piston displaceable within a cylinder member;

f. means for centering said piston with respect to said cylinder, said centering means including a means for pivotally coupling said piston to said biasing means; and

g. said diaphragm including an annular convolution thereon, the formation of said convolution being by chamber pressure and being facilitated by the pivotal freedom of said piston.

28. A control device as defined in claim 1 including a resilient means between said control means and said balance means, said resilient means being sufficiently weak to effect a lost motion connection between said balance means and said control means during the pivotal movement of said balance means about both of said axes.

29. A control device as defined in claim 1:

a. wherein said pair of biasing means is a pair of compressible coil springs;

b. including a guide means associated with each spring, each guide means also being connected to said housing at a connection point;

c. each connection point being associated with one of said springs and located at that part of said housing most remote from said one associated spring.

30. A control device as defined in claim 2 including:

a. a pair of rotatable screw means each of which is associated with one of said biasing means for adjusting the bias thereof;

b. said pair of rotatable screw means having mutually overlaping portions thereon.

31. A control device as defined in claim 15, wherein each of said biasing means has a line of force acting on said balance means, said biasing means being positioned with respect to said balance means such that the line of force of one of said biasing means passes through one of said axes at all positions of said balance means and the line of force of the other of said biasing means passes through the other of said axes at all positions of said balance means.

32. A control device as defined in claim 15 including a resilient means between said actuator and said balance means, said resilient means being sufficiently weak to effect a lost motion connection between said balance means and said actuator as said actuator moves between its first and second positions.

33. A control device as defined in claim 15 including:

34. A control device as defined in claim 15:

a. wherein said sensing means is a diaphragm;

b. wherein said diaphragm engages a piston;

c. said piston being displaceable within a cylinder member;

d. including means for centering said piston with respect to said cylinder, said centering means including a means for pivotally coupling said piston to said biasing means; and

e. said diaphragm including an annular convolution thereon, said convolution being formed by pressure and being effective to center said piston within said cylinder.

35. A control device as defined in claim 18, wherein each of said biasing means has a line of force acting on said balance plate, said biasing means being positioned with respect to said balance plate such that the line of force of one of said biasing means passes through one of said axes at all positions of said balance plate and the line of force of the other of said biasing means passes through the other of said axes at all positions of said balance plate.

36. A control device as defined in claim 22 wherein said first and second axes nearly intersect each other in the region of said pivotal part.

37. A control device as defined in claim 22 wherein said actuation means is effectively connected to said balance plate approximately at the midpoint between said hige pressure part and said low pressure part on said third axis.

38. A control device comprising:

a. a housing;

b. a chamber in said housing;

0. a sensing means defining a wall of said chamber,

said sensing means being displaceable through a stroke;

e. stop means cooperating with both said first and second sides of said balance means to define first and second axes about which said balance means pivots, said stop means including a low pressure part, a high pressure part, and a pivotal part, said first axis passing through said low pressure part and said pivotal part of said stop means, said second axis passing through said high pressure part and said pivotal part of said stop means, said pivotal part being spaced from a line passing through said high pressure part and said low pressure part.

g. a control means operatively coupled to said balance means;

39. A control deviceas defined in claim 38 wherein said first and second axes nearly intersect each other in the region of said pivotal part.

40. A control device comprising:

a. a housing;

b. a chamber in said housing;

e. stop means cooperating with both said first and second sides of said balance means to define first and second axes about which said balance means pivots, said stop means including a low pressure part, a high pressure part, and a pivotal part, said first axis passing through said low pressure part and said pivotal of said stop means, said second axis passing through said high pressure part and said pivotal part of said stop means, said pivotal part being spaced from a line passing through said high pressure part and said low pressure part;

a pair of adjustable biasing means coupled with said balance means, said biasing means being adjusted to exert different biasing forces on said balance means, whereby movement of said sensing means through one part of its stroke effects pivoting of said balance means about one axis, and movement of said sensing means through another part of its stroke effects pivoting of said balance means about the other axis; g. a single control means associated with said housing, said control means having a casing means and a single displaceable actuator extending outside said casing means, said actuator being operatively connected to said balance means; and

h. said control means having a first control mode at a first position of said actuator and a second control mode at a second position of said actuator, whereby pivoting of said balance means about one of said axes effects movement of said actuator through said first position and pivoting of said balance means about the other of said axes effects movement of said actuator through said second position so that adjustment of said biasing means effects adjustment of said control modes.

41. A control device as defined in claim 40 wherein said first and second axes nearly intersect each other in the region of said pivotal part.

42. A control device comprising:

a. a housing;

b. a chamber in said housing;

0. a sensing means defining a wall of said chamber, said sensing means being displaceable through a stroke;

a pair of biasing means, at least one of which being adjustable, each biasing means being elongated and each having a line of force acting on said balance means, the line of force of each biasing means coinciding with the longitudinal axis thereof, said biasing means being positioned with respect to said balance means such that the line of force of one of said pair passes through said first axis at all positions of said balance means and the longitudinal axis of the other of said pair passes through said second axis at all positions of said balance means,

g. a control means operatively coupled to said balance means;

' 43. A control device comprising:

a. a housing;

b. a chamber in said housing;

f. said stop means including a plate disposed in said housing above said balance means, a wall disposed in said housing below said balance means, a plurality of spherical members extending from both said first and said second sides of said balance means, said members of said first side being adapted to eni. whereby displacement of said sensing means through one part of its stroke effects pivoting of said balance means about said first axis and displacement of said sensing means through another part of its stroke effects pivoting ofsaid balance means about said second axis.

Claims

1. A control device comprising: a. a housing; b. a chamber in said housing; c. a sensing means defining a wall of said chamber, said sensing means being displaceable through a stroke; d. a balance means having first and second sides, said sensing means being operatively coupled to said balance means; e. stop means associated with both said first and second sides of said balance means to define first and second axes about which said balance means pivots; f. a pair of biasing means, at least one of which being adjustable and each having a line of force acting on said balance means, said biasing means being positioned with respect to said balance means such that the line of force of one of said pair passes through said first axis at all positions of said balance means and the line of force of the other of said pair passes through said second axis at all positions of said balance means; g. a control means operatively coupled to said balance means; h. whereby displacement of said sensing means through one part of its stroke effects pivoting of said balance means about said first axis and displacement of said sensing means through another part of its stroke effects pivoting of said balance means about said second axis.

3. A control device as defined in claim 1 wherein: a. said balance means is a balance plate; b. said stop means includes a first portion and a second portion; c. said stop means of said first portion includes a plurality of stops spaced apart from each other to define said first axis; and d. said stop means of said second portion includes a plurality of stops spaced apart from each other to define said second axis.

4. A control device as defined in claim 3 wherein: a. said first portion of said stop means is associated with said first side of said balance plate; and b. said second portion of said stop means is associated with said second side of said balance plate.

5. A control device as defined in claim 1 wherein said control means is a microswitch.

7. A control device as defined in claim 1 wherein: a. said housing has first and second ends; b. an inlet means communicates with said chamber, said inlet means being disposed in said first end; and c. an adjusting means is disposed at said second end and is accessible from the exterior of said housing.

9. A control device as defined in claim 1 wherein said stop means include: a. a plate disposed in said housing above said balance means; b. a wall disposed in said housing below said balance means; c. a plurality of protrusions extending from both said first and said second sides of said balance means, said protrusions from said first side being adapted to engage said wall, said protrusions from said second side being adapted to engage said plate.

12. A control device as defined in claim 1: a. wherein said sensing means is a diaphragm; b. wherein said diaphragm engages a piston; c. said piston being displaceable within a cylinder member d. means for centering said piston with respect to said cylinder, said centering means including a means for pivotally coupling said piston to said biasing means; and e. said diaphragm including an annular convolution thereon, said convolution being formed by pressure and being effective to center said piston within said cylinder.

13. A control device as defined in claim 1 wherein said stop means include: a. a first set of protrusions disposed in said housing apart from and below said balance means, said first set being adapted to engage said first side of said balance means; and b. a second set of protrusions disposed in said housing apart from and above said balance means, said second set being adapted to engage said second side of said balance means.

15. A control device comprising: a. a hollow housing; b. a sensing means displaceable through a stroke, said sensing means dividing said housing into a sensing chamber and a control chamber; c. a balance means in said control chamber operatively connected to said sensing means; d. a plurality of stop means co-operating with said balance means to define a pair of axes about which said balance means pivots; e. a pair of adjustable biasing means coupled with said balance means, said biasing means being adjusted to exert different biasing forces on said balance means, whereby movement of said sensing means through one part of its stroke effects pivoting of said balance means about one axis, and movement of said sensing means through another part of its stroke effects pivoting of said balance means about the other axis; f. a single control means associated with said housing, said control means having a casing means and a single displaceable actuator extending outside said casing means, said actuator being operatively connected to said balance means; and g. said control means having a first control mode at a first position of said actuator and a second control mode at a second position of said actuator, whereby pivoting of said balance means about one of said axes effects movement of said actuator through said first position and pivoting of said balance means about the other of said axes effects movement of said actuator through said second position so that adjustment of said biasing means effects adjustment of said control modes.

16. A control device as defined in claim 15 wherein: a. said balance means includes first and second sides; and b. said stop means are associated with said first and second sides.

17. A control device as defined in claim 16 wherein: a. said balance means is a balance plate; b. said stop means include a first portion and a second portion; c. said stop means of said first portion include a plurality of stops spaced apart from each other to define said first axis; and d. said stop means of said second portion include a plurality of stops spaced apart from each other to define said second axis.

18. A control device as defined in claim 17 wherein: a. said first portion of said stop means is associated with said first side of said balance plate; and b. said second portion of said stop means is associated with said second side of said balance plate.

20. A control device as defined in claim 15 wherein said first control mode is an actuation mode and said second control mode is a deactuation mode.

22. A control device comprising: a. a housing; b. a chamber in said housing; c. a sensing means defining a wall of said chamber, said sensing means being moveable through a stroke; d. a balance plate, said sensing means being coupled to said balance plate; e. stop means cooperating with said balance plate to define first, second and third axes, said stop means including a low pressure part, a high pressure part and a pivotal part, said first axis passing through said low pressure part and said pivotal part of said stop means said second axis passing through said high pressure part and said pivotal part of said stop means, said third axis passing through said high pressure part and said low pressure part, said pivotal part of said stop means being spaced from said third axis; f. a pair of biasing means, at least one of which being adjustable, operatively coupled to said balance plate and adjusted to exert different biases, whereby movement of said sensing means through one portIon of its stroke effects pivoting of said balance plate about said first axis and movement of said sensing means through another portion of its stroke effects pivoting of said balance plate about said second axis; g. a control means associated with said housing, said control means having an actuation means effectively connected to said balance plate approximately on said third axis, whereby small displacements of said balance plate at said pivotal part of said stop means are not transmitted to said actuation means.

23. A control device as defined in claim 22 wherein: a. said actuation means includes a resilient means attached to said balance plate; b. said actuation means further includes an actuating post between said resilient means and said control means; and c. said resilient means includes an extension thereon which is directed away from said pivotal part of said stop means and toward said midpoint.

24. A control device comprising: a. a housing; b. a chamber in said housing; c. a sensing means displaceable through a stroke, which means defines a wall of said chamber; d. a balance beam means having first and second ends; e. a recess in said balance beam means in the region of at least one of said ends; f. a plurality of stop means co-operating with said balance beam means, at least one of said stop means co-operating with said recess; g. said stop means defining first and second fulcrums about which said balance beam means pivots; h. a pair of biasing means at least one which being adjustable and each having lines of force acting on said balance beam means, the line of force of one of said pairs passing through said first fulcrum and the line of force of the other of said pairs passing through said second fulcrum; i. control means operatively coupled to said balance beam means; j. whereby displacement of said sensing means through one portion of its stroke effects pivoting of said balance beam means about said first fulcrum and displacement of said sensing means through another portion of its stroke effects pivoting of said balance beam means about said second fulcrum.

26. A control device comprising: a. a housing; b. a chamber in said housing; c. a displaceable sensing means defining a wall of said chamber; d. a balance means having first and second sides, said sensing means being operatively coupled to said balance means; e. stop means associated with both said first and second sides of said balance means to define first and second axes about which said balance means pivots; f. a pair of adjustable biasing means opposing displacement of said sensing means in one direction; g. a pair of rotatable screw means, each of said rotatable screw means being associated with one of said biasing means for adjusting the bias thereof; h. said pair of rotatable screw means having mutually overlapping portions thereon; i. a control means operatively coupled to said balance means; j. whereby displacement of said sensing means through one part of its stroke effects pivoting of said balance means about said first axis and displacement of said sensing means through another part of its stroke effects pivoting of said balance means about said second axis.

27. A control device comprising: a. a housing; b. a chamber in said housing; c. a displaceable diaphragm means defining a wall of said chamber; d. a biasing means opposing displacement of said diaphragm means in one direction; e. said diaphragm means engaging a piston displaceable within a cylinder member; f. means for centering said piston with respect to said cylinder, said centering means including a means for pivotally coupling said piston to said biasing means; and g. said diaphragm including an annular convolution thereon, the formation of said convolution beinG by chamber pressure and being facilitated by the pivotal freedom of said piston.

29. A control device as defined in claim 1: a. wherein said pair of biasing means is a pair of compressible coil springs; b. including a guide means associated with each spring, each guide means also being connected to said housing at a connection point; c. each connection point being associated with one of said springs and located at that part of said housing most remote from said one associated spring.

30. A control device as defined in claim 2 including: a. a pair of rotatable screw means each of which is associated with one of said biasing means for adjusting the bias thereof; b. said pair of rotatable screw means having mutually overlaping portions thereon.

33. A control device as defined in claim 15 including: a. a pair of rotatable screw means each of which is associated with one of said biasing means for adjusting the bias thereof; b. said pair of rotatable screw means having mutually overlaping portions thereon.

34. A control device as defined in claim 15: a. wherein said sensing means is a diaphragm; b. wherein said diaphragm engages a piston; c. said piston being displaceable within a cylinder member; d. including means for centering said piston with respect to said cylinder, said centering means including a means for pivotally coupling said piston to said biasing means; and e. said diaphragm including an annular convolution thereon, said convolution being formed by pressure and being effective to center said piston within said cylinder.

37. A control device as defined in claim 22 wherein said actuation means is effectively connected to said balance plate approximately at the midpoint between said high pressure part and said low pressure part on said third axis.

38. A control device comprising: a. a housing; b. a chamber in said housing; c. a sensing means defining a wall of said chamber, said sensing means being displaceable through a stroke; d. a balance means having first and second sides, said sensing means being operatively coupled to said balance means; e. stop means cooperating with both said first and second sides of said balance means to define first and second axes about which saId balance means pivots, said stop means including a low pressure part, a high pressure part, and a pivotal part, said first axis passing through said low pressure part and said pivotal part of said stop means, said second axis passing through said high pressure part and said pivotal part of said stop means, said pivotal part being spaced from a line passing through said high pressure part and said low pressure part. f. a pair of biasing means, at least one of which being adjustable and each having a line of force acting on said balance means, said biasing means being positioned with respect to said balance means such that the line of force of one of said pair passes through said first axis at all positions of said balance means and the line of force of the other of said pair passes through said second axis at all positions of said balance means; g. a control means operatively coupled to said balance means; h. whereby displacement of said sensing means through one part of its stroke effects pivoting of said balance means about said first axis and displacement of said sensing means through another part of its stroke effects pivoting of said balance means about said second axis.

39. A control device as defined in claim 38 wherein said first and second axes nearly intersect each other in the region of said pivotal part.

40. A control device comprising: a. a housing; b. a chamber in said housing; c. a sensing means defining a wall of said chamber, said sensing means being displaceable through a stroke; d. a balance means having first and second sides, said sensing means being operatively coupled to said balance means; e. stop means cooperating with both said first and second sides of said balance means to define first and second axes about which said balance means pivots, said stop means including a low pressure part, a high pressure part, and a pivotal part, said first axis passing through said low pressure part and said pivotal of said stop means, said second axis passing through said high pressure part and said pivotal part of said stop means, said pivotal part being spaced from a line passing through said high pressure part and said low pressure part; f. a pair of adjustable biasing means coupled with said balance means, said biasing means being adjusted to exert different biasing forces on said balance means, whereby movement of said sensing means through one part of its stroke effects pivoting of said balance means about one axis, and movement of said sensing means through another part of its stroke effects pivoting of said balance means about the other axis; g. a single control means associated with said housing, said control means having a casing means and a single displaceable actuator extending outside said casing means, said actuator being operatively connected to said balance means; and h. said control means having a first control mode at a first position of said actuator and a second control mode at a second position of said actuator, whereby pivoting of said balance means about one of said axes effects movement of said actuator through said first position and pivoting of said balance means about the other of said axes effects movement of said actuator through said second position so that adjustment of said biasing means effects adjustment of said control modes.

42. A control device comprising: a. a housing; b. a chamber in said housing; c. a sensing means defining a wall of said chamber, said sensing means being displaceable through a stroke; d. a balance means having first and second sides, said sensing means being operatively coupled to said balance means; e. stop means associated with both said first and second sides of said balance means to define first and second axes about which said balance means pivots; f. a pair of biasiNg means, at least one of which being adjustable, each biasing means being elongated and each having a line of force acting on said balance means, the line of force of each biasing means coinciding with the longitudinal axis thereof, said biasing means being positioned with respect to said balance means such that the line of force of one of said pair passes through said first axis at all positions of said balance means and the longitudinal axis of the other of said pair passes through said second axis at all positions of said balance means, g. a control means operatively coupled to said balance means; h. whereby displacement of said sensing means through one part of its stroke effects pivoting of said balance means about said first axis and displacement of said sensing means through another part of its stroke effects pivoting of said balance means about said second axis.

43. A control device comprising: a. a housing; b. a chamber in said housing; c. a sensing means defining a wall of said chamber, said sensing means being displaceable through a stroke; d. a balance means having first and second sides, said sensing means being operatively coupled to said balance means; e. stop means associated with both said first and second sides of said balance means to define first and second axes about which said balance means pivots; f. said stop means including a plate disposed in said housing above said balance means, a wall disposed in said housing below said balance means, a plurality of spherical members extending from both said first and said second sides of said balance means, said members of said first side being adapted to engage said wall, said members of said second side being adapted to engage said plate; g. a pair of biasing means, at least one of which being adjustable and each having a line of force acting on said balance means; h. a control means operatively coupled to said balance means; i. whereby displacement of said sensing means through one part of its stroke effects pivoting of said balance means about said first axis and displacement of said sensing means through another part of its stroke effects pivoting of said balance means about said second axis.