US3594521A

US3594521A - Electric snap switch with fluid-actuated toggle mechanism

Info

Publication number: US3594521A
Application number: US830973A
Authority: US
Inventors: Karl Roll; Carl A H M Waskowsky
Original assignee: PATINVEST AG
Current assignee: PATINVEST AG; PATINVEST PATENT- und INVESTMENT AG
Priority date: 1968-06-18
Filing date: 1969-06-06
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20
Also published as: GB1217480A

Abstract

A pressure-controlled snap switch in which the free end of a contact spring projecting between two spaced switch contacts is pivotable with a toggle motion from one contact against the other when a diaphragm in the switch housing is moved by the pressure of a liquid or gas. The movement of the diaphragm is transmitted to an adjustable control lever and the resulting swing of this lever is transmitted by a resilient link to a pivotable control spring whose free end is connected by a snap spring to the contact spring. The resilient link, whose opposite ends are connected to fixed points of the control lever and the control spring, may consist of a rod of rubber or plastic, or of an angular leaf spring or a torsion coil spring.

Description

United States Patent Karl Roll Leinielden-Oberaichen, Germany; Carl A. H. M. Waskowsky, Oberglatt,

(72] lnventors [54] ELECTRIC SNAP SWITCH WITH FLUID- ACTUATED TOGGLE MECHANISM 13 Claims, 6 Drawing Figs.

[52] U.S. Cl 200/83 R, 200/67 D [51] Int. Cl ..I-I01h 35/34 [50] Field of Search 200/83,

DIG. l, DIG. 2, 67 D; 337/347 Primary ExaminerRobert K. Schaefer Assistant Examiner-M. Ginsburg AttorneyKarl F. Ross ABSTRACT: A pressure-controlled snap switch in which the free end of a contact spring projecting between two spaced switch contacts is pivotable with a toggle motion from one contact against the other when a diaphragm in the switch housing is moved by the pressure of a liquid or gas. The movement of the diaphragm is transmitted to an adjustable control lever and the resulting swing of this lever is transmitted by a resilient link to a pivotable control spring whose free end is connected by a snap spring to the contact spring. The resilient link, whose opposite ends are connected to fixed points of the control lever and the control spring, may consist of a rod of rubber or plastic, or of an angular leaf spring or a torsion coil spring.

ELECTRIC SNAP SWITCH WITH FLUlD-ACTUA'IED TOGGLE MECHANISM The present invention relates to an electric pressure-controlled snap-action switch which is especially suitable for being employed in connection with a laundry or dishwashing machine or the like and is provided with at least one mobile contact spring which projects between and is adapted to engage one or the other of a pair of normally fixed contacts and the operation of which may be controlled by the movements of an element such as a diaphragm which, when subjected to the pressure of a liquid or gas, acts upon a control lever which is loaded by an adjusting spring and acts upon a control spring or tongue which is operatively interposed between the control lever and the contact spring and is connected to the latter by a toggle or snap spring.

The conventional snap switches of the type above described are provided with a rigid tappet which is secured to the control lever and whose tip engages the control spring which is associated with the contact spring and, when the control lever swings, also efi'ects a pivoting movement of the snap spring.

Since in the operation of the switch the control lever as well as the control and contact springs carry out pivoting movements about their respective axes, these pivoting movements result in reductions in the effective length of the control spring. Since the free end of the control spring is pivotably connected to the snap spring which, in turn, is pivotably connected to the contact spring, these reductions in the effective length of the control spring have a disadvantageous effect upon the snap spring and through the latter also upon the mobile contact spring.

According to the present invention it has now been discovered that this disadvantage of the known snap switches of the type described may be eliminated by connecting the control lever and the control spring or tongue to each other by means of a resilient elongate link instead of providing the control lever with a rigid tappet whose free end or tip merely bears upon the control spring.

This resilient link forms a universal joint between the control lever and the control spring which permits both ends of this element to follow independently of each other the pivoting movements of the control lever and the control spring.

In order to insulate the control lever and the control spring electrically from each other, it is one feature of the present invention to make this connecting element of an electrically insulating material, e.g. rubber or a suitable plastic. This connecting element may, for example, consist of a pin or rod, a leaf spring or a torsion coil spring. By making this element of a suitable resilience different from the resilience of the control spring, the connecting element may also serve for temporarily storing the pressure or tension which is exerted by the control lever through this element upon the control spring. When the control spring is about to snap through its dead center position to the other side, the resilient connecting element will release this stored force and thereby accelerate the snap action. Owing to this storing action of the connecting element, the control spring will therefore also be pivoted from one to the other side and with a snap action through its dead center position even though the diaphragm will be acted upon only by a slow variation in pressure and will therefore pivot the control lever very slowly. The contacts on the contact spring which is swung by the control spring and the interposed toggle or snap spring will therefore always rapidly make or break with the fixed contacts.

According to one preferred embodiment of the invention, the resilient connecting element is in the form of a solid rod of elastomeric material, i.e. rubber or a suitable plastic, whose opposite ends are secured to the control lever and the control spring by being inserted into bores of a smaller diameter in this lever and spring and by being provided near these ends with annular grooves into which the edges of the bores engage.

If the resilient connecting element is in the form of a leaf spring, this spring is preferably bent at such an angle that its effective length is determined by only one arm of this spring, while the other arm extends substantially in the direction of movement of the control lever and thus practically does not affect the spring action of this leaf spring. The upwardly bent arm may be provided with an aperture in which a stop member may engage so as to limit the extent of the movement of the leaf spring relative to the control lever.

In addition, the leaf spring is preferably provided with a longitudinal slot through which the free end of the tappet may extend which projects from the diaphragm plate and acts upon the control lever. If this leaf spring is made of metal rather than of an insulating material, it is advisable to insulate it electrically from the switch housing by providing an insulating member between this spring and the control spring and/or the control lever.

One of the fixed" contacts, which is operatively associated with the contact spring and preferably forms the contact which the mobile contact spring engages when the diaphragm of the switch is not under pressure, is adjustable to different distances from the other fixed contact by being mounted on the free end of a spring whose other end is secured to the switch housing and to a connecting terminal lead which projects from the housing. This spring presses against a setscrew by which it is adjustable relative to the other fixed contact. For this purpose, this spring is preferably resilient only adjacent to the area where it is secured to the switch housing, while the other part of this spring is reinforced by ribs, stifiening corrugations or the like so as to be relatively nonresilient.

In order to prevent the spring carrying the adjustable contact from exerting a pressure upon the switch housing which might possibly damage the latter, the elasticity constant of this spring is preferably made as small as possible by making this spring of a considerably thinner material than the terminal lead thereof.

These and additional features and advantages of the present invention will become further apparent from the following detailed description thereof which is to be read with reference to the accompanying drawing in which: I

FIG. 1 shows a cross section of a switch according to a first embodiment of the invention in its off position;

FIG. 2 shows a cross section of the switch according to FIG. I in its on position;

FIG. 3 shows a cross section of a switch according to a second embodiment of the invention in its off position;

FIG. 4 shows a view of a part of the leaf spring as seen from the left thereof in FIG. 3;

FIG. 5 shows a modification of a ing to FIG. 3; and

FIG. 6 shows a cross section of a switch according to a third embodiment of the invention in its off position.

The snap switch according to the invention as illustrated in FIGS. 1 and 2 comprises a diaphragm l which may be lifted by the pressure of a liquid or gas entering a chamber in the lower part of the switch housing 10 through a hose nipple 2 or the like so that a central tappet 4 on a plate 3 which is connected to the upper side of the diaphragm 1 will then act upon a control lever 6 which is pivotably mounted at one end about a fulcrum 5. The other end 7 of this lever 6 acts upon the lower end of an adjusting spring 8 whose upper end engages and is adapted to be adjusted by a setscrew II which is screwed into a tubular extension 9 of the switch housing 10.

Control lever 6 is further operatively associated with a mobile contact spring 13 one end of which is rigidly secured to a part of the housing 10 by a rivet 12 while its free end 15 carrying a contact 14 projects between a fixed contact 16 and an adjustable contact 17. Contact spring 13 consists of a strong leaf spring which may bend resiliently only adjacent to its lefthand end which is clamped in a fixed position by the rivet 12. This contact spring 13 is operatively associated with a control spring or tongue 18 one end of which is likewise clamped by the rivet l2 and which is able to pivot from one to the other part of the switch accordside of contact spring 13 through a longitudinal slot which is provided in the contact spring 13. This control spring 18 is operatively associated with a barrel-shaped snap or toggle spring 19 one end of which acts upon the free end 20 of control spring 18 while its other end is supported by and acts upon the inner edge 21 of the end of the slot in contact spring 13 through which

springs

18 and 19 are pivotable.

As may further be seen in FIGS. 1 and 2, control lever 6 is bent so as to be pivotable outside of the area within which contact spring 13 and control spring 18 are pivotable.

Control lever 6 and control spring 18 are directly connected to each other by a rubber rod 22 whose

opposite ends

23 and 24 project through bores 25 and 26 in control lever 6 and control spring 18, respectively. For firmly securing the rubber rod 22 to lever 6 and spring 18, rod 22 is provided near its opposite ends with

annular grooves

27 and 28 into which the edges of the bores 25 and 26 tightly engage. This rubber rod 22 forms an almost ideal resilient link between the control lever 6 and the control spring 18 which permits the

ends

23 and 24 of rod 22 to follow the swing of the control lever 6 and also of the control spring 18 without danger that the variations in the effective length of rod 22 caused by the difierent pivoting movements will have any noticeable effect. This rubber rod 22 also serves as an accumulator which stores the pressure transmitted thereto from the diaphragm I through the control lever 6, and which transmits this stored pressure to the control spring 18 shortly before the latter is pivoted beyond its dead center position. This rubber rod 22 has the further purpose of serving as an electric insulator between the control spring 18 and the control lever 6. i

The adjustable contact 17 is secured to one end of a leaf spring 30 which is bent twice at an angle and whose other end is electrically connected to a terminal lead 29 which projects from the switch housing 10. Leaf spring 30 and terminal lead 29 are connected to each other and secured to the housing by a rivet 31. For adjusting the position of the contact 17, the end 32 of leaf spring 30 carrying this contact on its side engages the end of a setscrew 33 which is screwed into a tubular part 34 of the switch housing 10. Leaf spring 30 is further provided with a stiffening corrugation 35 which insures that spring 30 will bend resiliently only next to its left-hand end I face 36 of thebottom part 37 of the switch housing. When diaphragm l is in this inactive position, the control lever 6, the control spring 18 and the contact spring 13 are likewise in their respective inactive positions in which the adjusting spring 8' presses the control lever 6 against a fixed stop 39 at the inside of housing 10 and the snap spring 19 bearing upon the free end of the control springl8 presses the contact spring l3 upwardly so that its contact 14 presses against the adjustable contact 17.

FIG. 2 shows the same switch in its on position in which the diaphragm l is lifted by the pressure acting upon its lower side and the control lever 6 is thereby pivoted against the action of the adjusting spring 8 toward the control spring 18. Owing to this pivoting movement, the control lever 6 exerts through the rubber rod 22 a forceupon the control spring 18 so that this spring has the tendency to pivot against the action of snap spring 19 through its dead center position to the other side. This pivoting movement of control spring 18 through its dead center position issupported by the pressure which, as previously described, is stored in the rubber rod 22. After the control spring 18 has passed its dead center position, snap spring 19 presses the contact spring I3 suddenly into its on position as shown in FIG. 2 in which the contact 14 engages the contact 16.

When the pressure upon the lower side of diaphragm I decreases, the diaphragm will again move downwardly and the control lever 6 will also pivot back to its inactive position as shown in FIG. 1. This also causes the control spring 18 to be retracted with the result that the contact spring 13 will again snap over to the other side. Since the return movement of control lever 6 also results in an extension of the rubber rod 22 in its longitudinal direction, a tension will be stored in this rod with the result that, when control spring 18 snaps over to its other side, this movement will be accelerated by the release of the tension of rod 22.

FIG. 3 illustrates a modification of the switch according to the invention likewise on the off position, the same as the switch according'to FIG. I. The corresponding parts of the the same reference numerals. In place of the rubberrod 22 according to FIGS. 1 and 2, the switch according to FIG. 3 is provided with an angularly bent leaf spring 40. The free end 41 of the horizontal arm 42 of this spring 40 is secured by a rivet 43 to a tab 44 which is partly stamped upwardly out of the control lever 6 and extends parallel to the general plane of that lever. The other arm 45 of spring 40 which is bent upwardly from the arm 42 extends, however, substantially paral-' lel to the direction in which the control lever 6 is pivotable and its free end 46 serves for supporting the end of the control spring 18 which engages the snap spring 19.

As illustrated particularly in FIG. 4, leaf spring 40 is provided with a longitudinal slot 47 which increases the elasticity of this springand has a sufficient width to permit the upper end 48 of the tappet 4 on the diaphragm plate 3 to project freely therethrough. The free end of the arm 46 of leaf spring 40 is bifurcate in the manner shown in FIG. 4 so as to form two prongs 49 which reach around and over the sides of spring 18 and together with the edge of a central boss 50 of spring 40 form a double knife edge bearing for the control spring 18 on opposite faces of the latter.

Since in this embodiment of the invention the metallic leaf spring 40 forms an electric connection between the control spring 18 and the control lever 6, the fixed stop member-39 which limits the extent of the stroke of the control lever 6 consists of an electrically insulating material such as, for example, a plastic. The effect of the switch which is equipped with such a leaf spring 40 is identical with that of the switch according to FIGS. 1 and 2 which is provided with a rubber rod 22.

FIG. 5 illustrates a modification of the leaf spring 40 as last described. Instead of being provided with the longitudinal slot 47, this leaf spring according to FIG. 5 is provided

withtwo apertures

51 and 52. While the aperture 51 in the horizontal arm 42 is large enough to permit the upper end 48 of the tappet 4 to move freely therethrough, the aperture 52 in the other arm 45 of the leaf spring receives the bentover end 53 of a stop member 54 projecting from the control lever 6. The end 53 of stop member 54 has such a clearance in the aperture 52 that the arm 45 of leaf spring 40 and thus also the entire spring can move for a distance h relative to the control lever 6. The stop projection 53 therefore limits the extent of the stroke h of leaf spring 40 relative to the control lever 6 which has the advantage that the force which is stored in and by the leaf spring 40 will become effective only in the immediate vicinity of the dead center position of the control spring 18. By limiting the stroke h of leaf spring 40 so as to make it effective only within the particular area in which it is'of practical value, the further advantage is attained that the storage of force by ad in this spring requires only a relatively small amount of energy which, in turn, requires only small variations in pressure upon the diaphragm 1, even though the fixed contacts are spaced from each other as shown in the switch according to FIG. 3.

FIG. 6 finally illustrates a switch similar to those previously described in which, however, the rubber rod 22 according to FIGS. 1 and 2 or the leaf spring 40 according to FIG. 3 is replaced by a torsion coil spring 55 of spring steel provided with a loop 56 in the common swing plane of lever 6 and tongue 18. For electrically insulating the control lever 6 as well as this torsion spring 55 relative to the control spring 18, the latter is provided with a part 57 which consists of an electrically insulating material such as, for example, a plastic. This part 57 comprises a short tube 58 which projects through a bore 59 in the control spring 18. Thanks to the provision of this insulating part 57, the fixed stop member 39 may consist of any desired material just like the stop member 39 according to FIG. 1.

Although out invention has been illustrated and described with reference to the preferred embodiments thereof, we wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed our invention, we claim:

1. A snap switch comprising:

contact means including a mobile leaf spring movable between a first and a second position;

a swingable tongue adjacent said leaf spring;

a toggle spring interconnecting said tongue and said leaf spring for translating a swing of the former past a dead center position into an opposite movement of the latter between said first and second positions thereof;

a lever generally parallel to and spaced from said tongue swingable between an unoperated and an operated positlon;

an elongate resilient link with one end fixed to said lever and another end fixed to said tongue, said link extending generally tranversely between said lever and said tongue while allowing limited relative motion thereof;

and actuating means for swinging said lever between said unoperated and operated positions thereof with elastic deformation of said link for the storage therein and sub- 3. A snap switch as defined in claim 2 wherein said lever has a pivoted end fulcrumed on said housing and a free end provided with adjustable biasing means opposing a swing of said lever into said operative position by the pressure of said fluid, said link being fixed to said lever at a point intermediate said pivoted and free ends.

4. A snap switch as defined in claim 3 wherein said leaf spring and said tongue are clamped to said housing on the side of said free end with reference to said link.

5. A snap switch as defined in claim 1 wherein said link is a rod of elastomeric material.

6. A snap switch as defined in claim 5 wherein said rod has grooved ends fitted into holes of said lever and said tongue.

7. A snap switch as defined in claim 1 wherein said link is a bent spring.

8. A snap switch as defined in claim 7 wherein said bent spring is generally L-shaped with a first arm substantially parallel to said lever and with a second arm substantially perpendicular thereto, said first arm and said lever being closely juxtaposed and provided with aligned apertures traversed by a part of said actuating means.

9. A snap switch as defined in claim 7, further comprising restaining means on said lever engaging said bent spring with play for limiting the elastic deformation thereof upon a swinging of said lever between said unoperated and operated positions.

10. A snap switch as defined in claim 7 wherein said bent spring is coiled into a loop substantially midway between said lever and said tongue.

11. A snap switch as defined in claim 10 wherein said loop lies in the common swing plane of said lever and said tongue.

12. A snap switch as defined in claim 7 wherein said bent spring is a blade with a bifurcate end having prongs clamping said tongue between them.

13. A snap switch as defined in claim 12 wherein said leaf spring is longer than said tongue and is longitudinally slotted for giving passage to said tongue upon a swinging thereof past dead center.

Claims

1. A snap switch comprising: contact means including a mobile leaf spring movable between a first and a second position; a swingable tongue adjacent said leaf spring; a toggle spring interconnecting said tongue and said leaf spring for translating a swing of the former past a dead center position into an opposite movement of the latter between said first and second positions thereof; a lever generally parallel to and spaced from said tongue swingable between an unoperated and an operated position; an elongate resilient link with one end fixed to said lever and another end fixed to said tongue, said link extending generally tranversely between said lever and said tongue while allowing limited relative motion thereof; and actuating means for swinging said lever between said unoperated and operated positions thereof with elastic deformation of said link for the storage therein and subsequent release of a mechanical forCe swinging said tongue past said dead center position to control the position of said leaf spring.

2. A snap switch as defined in claim 1, further comprising a housing supporting said contact means, said tongue and said lever, said actuating means including a diaphragm substantially parallel to said lever and mechanically coupled therewith, said diaphragm forming part of a fluid chamber in said housing provided with inlet means for the admission of a pressure fluid to displace said lever.

3. A snap switch as defined in claim 2 wherein said lever has a pivoted end fulcrumed on said housing and a free end provided with adjustable biasing means opposing a swing of said lever into said operative position by the pressure of said fluid, said link being fixed to said lever at a point intermediate said pivoted and free ends.

7. A snap switch as defined in claim 1 wherein said link is a bent spring.