US2792467A - Switches - Google Patents

Description

mmmz May 14, 1957 Filed Nov. 6, 1952 W. H. HOLLINSHEAD SWITCHES 2 Shets-Sheet 1 IN VENTOR BY SZ WQmQu% ATTORNEY May 14, 1957 Filed Nov. 6, 1952 w. H. HOLLINSHEAD 2,792,467

SWITCHES 2 Sheets-Sheet 2 103 6K 63 I 1 3 (515 I ATTORNEY United States Patent 1 2,792,467 SWITCHES William H. Hollinshead, St. Paul, Minn., assignor to Control Manufacturing Company, St. Paul, Minn., a partnership Application November 6, 1952, Serial N 0. 319,148 6 Claims. (Cl. 209-84) This invention relates to an improvement in switches and deals particularly with a simple circuit switch designed for operation upon changes in liquid level.

Switches are often required for closing a circuit when a predetermined liquid level is reached. These switches have to be extremely dependable in their operation and at the same time must be simple in construction so that they may be low in cost. The present invention resides in the provision of a switch which will accomplish these requirements.

A feature of the present invention resides in the novel manner in which the various parts of the switch are mounted. The switch contacts are mounted upon a panel of insulation provided with projections at opposite ends thereof. These projections spring into a U-shaped frame which in turn is supported within the relatively rigid outer housing. When contained within the housing 'the walls of the U-shaped support can not spread apart sufficiently to disengage the supported insulation panel.

A further feature of the present invention resides in the particular form of toggle arrangement which controls the contact blades. The contact blades are provided with aligned downwardly projecting ears. An angularly shaped toggle lever which acts in the manner of a bell crank lever is provided with an upwardly directed extremity. An insulation member is interposed between the upwardly directed arm of the toggle lever and the downwardly projecting ears of the contact blades. By pivotal movement of the bell crank type of lever the grooved member may be swung into and out of alignment with the upwardly directed end of the bell crank lever, thereby urging the contact blades into and out of contact.

A further feature of the present invention resides in a switch which embodies'elements which comprise a toggle unit and in which one of the toggle levers comprises a block of insulation which is grooved to accommodate retaining 'members on the contacts and on the other toggle lever.

This block of insulation may thus be'operated to urge the switch contacts into and out of circuit closing position. An added feature of the present invention lies in the provision of a toggle unit of the type described above in which the block of insulation is provided with projections which extend between the contacts engaged and is held from lateral movement thereby. Thus the block. of insulation is held in place regardless of the positions of the contact blades or of the other toggle lever.

An added feature of the present invention lies in the manner in which the spring urging the switch contacts into one extreme position is adjusted. The helical tension spring is connected at one end to the switch operating lever and extends into a tubular casing at its other end. A screw extends into the tubular member and is threaded into the spring. By engaging the head of the screw with the opposite end of the tubular member from that containing the spring the tension upon the spring can be adjusted by rotating the screw in one direction or the other.

An added feature of the present invention resides in the provision of a switch which is controlled by one or more weights which are denser than the liquid into which they extend. These weights always exert a downward force upon the operating lever, but the immersion of the weights in the liquid decreases the downward pull upon the operating lever sufl'iciently to permit the lever biasing spring'to actuate the switch contacts. l

2,792,467 Patented May 14, 15557 p ce the position of the view being indicated by the line 4-4 of Figure 3.

Figure 5 is a sectional view through the switch, the position of the section being indicated by the line 5--5 of Figure 2.

Figure 6 is a sectional view through the switch, the

' position of the section being indicated by the line 6--6 of Figure 2.

Figure 7 is a bottom plan view of the insulation platform which supports the contact plates.

Figure 8 is a perspective view of the toggle member which actuates the contact plates. 7 Figure 9 is a perspective view of one of the members forming a part of the toggle lever structure.

Figure 10 is a perspective view of the operating lever.

Figure 11 is a perspective view of the shell in which the operating mechanism is mounted.

Figure 12 is a perspective view of the switch lever sup porting frame.

The switch is indicated in general by the letter A and is shown as it appears when closed in Figure 1 of the drawings. The switch A is actuated by means of an operating lever 10 which projects from the case in a manner which will be later described. A chain or other flexible member 11 is connected to the operating lever 16 and supports a pair of weights 12 and 13 which are usually identical in form.

The weights 12 and 13 are supported at the desired elevation by suitable means such as a spring ring 14 which is placed through the chain to limit the downward movement of the weights. The weights are provided with apertures 15 and 16 extending therethrough for accommodation of the chain 11. The spring rings 14 thus may serve to adjust the elevation of the chains, one of which may remain immersed in the liquid and the other of which may be above the normal liquid level line.

-In the particular embodiment illustrated the switch is designed to be opened by the weights 12 and 13 when the liquid level drops sufiiciently so that the weight above the water overcomes the force of the lever biasing spring which will be later described. Such an arrangement is designed for use, for example in conjunction with sump pumps which are designed to pump out liquid from the sump when a certain amount accumulates therein. When the level of liquid raises sufioiently to lessen the downward force upon the operating lever below that of the switch lever biasing spring, the lever is actuated to close the contacts and close the circuit to the sump pump or other device.

The weights 12 and 13 are provided with a substantially flat lower end 17 and a slightly tapering lower body portion H which extends somewhat more than half the height of the weight. The weights are provided with a slightly tapering portion 2t: which tapers upwardly and inwardly and a frusto-coni al upper portion 21. This shape of weight has been found extremely effective for its prescribed purpose. The weights are molded from any suitable material such as hard rubber or the like.

The operating mechanism of the switch is mounted within a substantially U-shaped support 22 which forms the bottom of the switch housing. The support 22 includes a bottom panel 23 and parallel upwardly extending side panels 24 and 25. A front flange 26 extends upwardly from the forward edge of the bottom panel 23 and is drilled at 27 to accommodate a metal screw or is threaded to accommodate a machine screw designed to hold the cover plate to the support to form the complete switch housing.

A pair of elongated slots 29 and 30 are provided in the end walls 24 and 25 near the upper extremity thereof. For the purpose of simplicity in stripping the stock from these slots 29 and 36, the slots may be T-shaped in form as illustrated with a connecting notch 31 or 32 extending from the transverse notch to the top of the corresponding end wall. 7 a

An insulation platform 33 is supported between the end walls 24 and 25. As indicated in Figures 4 and 7 of the drawings this insulation block 33 is provided with a pair of oppositely directed projections 34 and 35 of proper size and shape to fit snugly into the slots 29 and 30 respectively. Thus by merely springing the end walls 24 and 25 outwardly and slipping the insulation platform 33 between these end walls, the projections willenter their respective slots and hold the platform suspended above the bottom panel 23 as shown in the various figures of the drawings.

A switch lever supporting frame 36 is mounted upon the bottom panel 23 of the support 22. This frame 36 is U-shaped in section including a bottom panel 37 shown in Figures 4 and 6 of the drawings and upwardly extending similar side walls 39 and 40 extending upwardly in parallel relation from opposite sides thereof. The bot tom panel 37 is provided with integral ears 41 at opposite ends of the end wall which are provided with threaded apertures to accommodate mounting screws 42. The mounting screws 42 extend through the bottom panel 23 of the switch housing and into the ears 41 to hold the bottom panel 37 flush upon the bottom wall 23.

The parallel walls 39 and 40 are provided with irregularly shaped notches 43 intermediate the ends thereof. These notches include downwardly and inwardly inclined portions 44 which adjoin outwardly and downwardly inclined portions 45. From a fulcrum point of greatest width indicated at 46, the notches extend downwardly and inwardly as indicated at 47. Thus the notches form which cause the operation of the apparatus.

The operating lever is illustrated in detail in Figure 10 of the drawings. This lever 19 includes an elongated arm 49 which is of inverted channel shaped construction, the longitudinal edges of the arm being bent downwardly to reinforce the structure. The arm is off-set at 50 and joins a generally U-shaped frame of angular cross section including one arm 51 whichforms substantially an extension of the arm portion 49, a parallel opposite arm 52 and a connecting arm 53. The arms 51 and 52 are provided with opposed inwardly directed lugs 54 and 55 and the connecting member 53 is provided centrally with an aperture 56 to which one end of a biasing spring may be connected.

The lever which is directly actuated by the operating lever 10 is illustrated in Figure 9 of the drawings. This lever includes an elongated body portion 57 having one pair of laterally projecting ears 59 near one extremity thereof and a second pair of laterally extending ears near the other end thereof. An upwardly directed lever arm' 61 extends at substantially right angles to the elongated arm 57 and is provided with a slightly rounded upper extremity 62. An elongated centrally located slot 63 extends through much of the length of the arm 57 and through much of the length of the angularly extending arm 61, being in the ends of these arms which are joined. An aperture 64 is provided in the arm 57 spaced from an end of the slot 63, this aperture providing an anchoring place for a lever biasing spring which will be later described.

opposed fulcrum points for supporting the pivoted levers 4 The control lever 16 and the angular lever 65 illustrated in Figure 9 are assembled with the lever support 36. The lugs 54 and of the operating lever 113 are engaged with one fulcrum point .46 in each of the notches 43. The laterally extending lugs or cars of the angular lever are engaged with the other fulcrum point of each notch 43. A spring 66 is anchored between the aperture 64 of the angular lever 65 and the aperture 56 of the control lever 10. Pivotal movement of the angular lever 65 is controlled by the engagement of the lugs or ears 59 with projections 67 and 69 at one end of each of the side walls 39 and 46 of the switch supporting frame 36. Pivotal movement of the control lever 19 is limited by engagement of "the cross member 53 with projections 70 and 71 on the side walls 39 and 40 of the switch supporting frame 36. When the control lever 10 is moved upwardly the angular lever 65 remains inactive until the spring 66 directs an upward pull upon the free end of the lever arm 57. At this time the angular lever moves into its opposite extreme position with the lugs 59 engaging the upper projections 69. When the control lever 10 is lowered the angular lever 65 remains stationary until the force of the spring 66 directs a downward pull upon the free end of the lever arm 57, thus swinging the angular lever 65 until its projecting lugs 59 engage the lower projections 67 of the supporting frame 36.

In order to bias the operating lever upwardly, I provide a helical spring 72 which is connected at one end to the aperture 56 of the cross member 53. This spring 72 extends upwardly into a tubular sleeve 73 extending through the platform 33. The sleeve 73 includes a relatively small diameter lower portion 74 and a relatively large diameter portion 75, the two portions forming a shoulder therebetween which engages against the upper surface of the platform 33 and prevents the sleeve from being pulled downwardly. A machine screw 76 or other such threaded element extends downwardly through the sleeve 73 and is threaded into the upper end of the spring 72. By rotating the screw 76 in one direction the spring may be pulled upwardly into the tubular member 73, the internal diameter of this sleeve being such as to prevent Ithe spring from slipping off the end of the threaded member. Rotation of the threaded member in the opposite direction decreases the tension on the spring. The tension is usually sufficient to bias the operating lever 10 into position with its outer end or handle end upwardly.

An insulation block 77 cooperates with the up-turned arm 61 of the angular or bell crank lever 65 to form a pair of toggle levers. The insulation block 77 extends at least the width of the space contacts to be engaged' and is provided with an upwardly directed groove 79 in its undersurface designed to rest upon the rounded upper edge 62 of the lever arm 61. The upper end of the insulation block is provided with a central upward projection 80 designed to fit between the spaced contact blades engaged and includes spaced grooved portions 81 and 82 on opposite sides of the central projection.

As indicated in Figure 7 of the drawings the spaced contact blades 83 and 84 are anchored between locating ribs on the undersurface of the block or platform 33. The locating ribs 85 project downwardly in spaced A similar pair of downwardly projecting ribs 86 aceommodate the contact blade 84 therebetween and properly locate this blade. Rivets or other fastening means 87 and 89 connect these blades electrically with terminal plates: 90 and 91 on the upper side of the platform 33 as shown in Figure 3. Screws 92 and 93 extend into the terminal plates 96 and 91 to permit the connection of a wire to each plate.

The free ends of the contact blades 83 and 84 support contact points94 and 95 respectively. These contact points are engageable with fixed contact points 96 and 97 (see Figure 6) which are connected by rivets or other fastening means extending through the platform with contact plates 99 and 100. These contact plates are also provided with threaded screws 101 and 102 by means of which the plates may be connected to a conductor.

In assembling the switch the contact blades with their points attached are mounted upon the platform 33 so that the contact blades are secured to their respective contact plates and the fixed points are connected with their respective terminals. The operating lever 10 and the angular lever 65 are supported upon the switch arm support frame 36 as previously described and the springs are attached to these levers. The frame 36 is attached to the bottom panel 23 of the support 22 and the platform 33 is sprung between the end walls 24 and 25 of this element. The spring 72 is inserted into the sleeve 73 and anchored in place. During the assembly operation the block 77 is interposed between the upper end 62 of the anchor lever 65 and down-turned ears 103 on the switch blades 83 and 84. These ears 103 are formed by doubling the ends of the contact blades back upon themselves and bending the extremities of the rearwardly bent portions downwardly.

The housing also includes a 'U-shaped body member 104 including a rear wall 105 and parallel side walls 106 and 107. The side walls 106 and 107 extend over the side panels 24 and 25 of the support 22 and are secured thereto by screws or other fastening means. The side walls 106 and 107 thus hold the side walls 24 and 25 from spreading apart and thus prevent the platform 33 from being disengaged.

This provides a switch housing having an open front and open top. The remaining two sides are closed by a cover element 109 having a top wall 110 and front wall 111. Flanges 112 and 113 (see Figures 2 and 4) telescope marginal portions of the side walls 106 and 107 and :a rear flange 114 lies rearwardly of the upper margin of the rear wall 105 to hold the housing assembled. A securing screw 115 extends through the lower margin of the cover and into the aperture 27 of the flange 26 to hold the structure assembled. Registering notches 116 and 117 in the support 22 and the enclosure portion 104 respectively permit the operating lever 10 to extend through the side of the housing for connection with the chain 11.

'It will be noted that when the contact points are in electrical contact the insulation block 77 engages the switch arms between the anchored ends and the point supporting ends so as to exert a force upon the contact arms. Furthermore, it will be noted that when the contacts are closed the toggle linkage formed by the block 77 and the lever arm 61 is substantially aligned so that the spring force of the contact arms can not exert any material force upon the levers tending to move them to their other extreme position. In disengaged position of the contact blades, the spring force is released both from the contact blades and the toggle levers.

In accordance with the patent statutes, I have described the principles of construction and operation of my switch, and while I have endeavored to set forth the best embodiment thereof, I desire to have it understood that obvious changes may be made within the scope of the following claims without departing from the spirit of my invention.

Iclaim:

1. A switch including a strip bent into angular formation, means hingedly supporting said strip adjacent to the point of bend thereof, means engaging one end of said strip and pivoting the same, means limiting pivotal movement of said strip in each direction, a pair of contact blades supported in substantially parallel spaced relation, and an insulation block having a groove in one end thereof in which is engaged the other end of said angularly bent strip, said blades extending at substantially right angles to said other strip end, and means pivotally connecting said insulation block to said contact blades, said other end of said angularly bent strip and said insulation block forming a pair of toggle levers to actuate said contact blades upon pivotal movement of said angular strip, and independent means connected to said lever for selectively biasing said strip to either extreme position.

2. The structure described in claim 1 and including projecting means extending between said spaced contact blades.

3. The construction described in claim 1 and including substantially right .angularly extending ears on said contact blades and grooves in said insulation block on the end thereof opposite the first named groove to accommodate said ears and to form a pivotal connection therewith.

4. A switch including an operating lever, means pivotally supporting said operating lever, an angular lever, means pivotally supporting said angular lever adjacent the point of bend therein, and spring means connecting said operating lever and said angular lever to urge said levers toward their respective pivots, resilient means biasing said operating lever toward one extreme position, said resilient means including a helical spring connecting to said operating lever, a tubular enclosure into which said spring extends, and a threaded member threadably engageable with said helical spring to adjust the tension on said spring upon rotation of said threaded member.

5. In a switch frame means, a lever pivotally supported intermediate its ends by said frame means for movement between two extreme positions, a pair of spaced contact blades mounted in substantially parallel spaced relation to the frame means, and an insulating block having a groove in one end thereof designed to accommodate one end of the lever and having rocking engagement at its other end with said contact blades, said one end of the lever and said insulation block forming toggle means to actuate said contact blades upon pivotal movement of said lever, independent means connected to said lever for selectively biasing said lever to either extreme position and including projecting means on said block extending between said spaced contact blades.

6. A switch including contact means, an operating lever actuating said contact means, a flexible means depending from said operating lever, means of greater density than water supported on said flexible means, said means continuously exerting a downward force on said lever, and means for biasing said operating lever upwardly, said means on the flexible means operating upon substantial submersion to reduce the effective pull upon said flexible means and said biasing means acting to elevate said operating lever.

References Cited in the file of this patent UNITED STATES PATENTS 564,283 Hunt July 21, 1896 842,554 Johnson Jan. 29, 1907 1,610,213 Ville Dec. 7, 1926 1,924,639 Corcoran Aug. 29, 1933 2,314,995 Lennholm Mar. 30, 1943 2,354,282 Shaw July 25, 1944 2,454,185 Kmiecik Nov. 16, 1948 2,456,112 Dodd Dec. 14, 1948 2,487,374 Riche et al Nov. 8, 1949 2,548,280 Allan Apr. 10, 1951 2,564,655 Binford Aug. 21, 1951 2,572,622 Hollinshead Oct. 23, 1951 2,601,152 Kmiecik June 17, 1952 OTHER REFERENCES Patent Law and Practice (pages 3045), Leon J. Amdur, 1945, Clark Boardman Co., Ltd., New York, N. Y.

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