US 3098141 A
Description (OCR text may contain errors)
G- WINTRISS ENCLOSED PRECISION SWITCH Filed Oct. 4, 1960 July 16, 1963 I DOUBLE 63 6t THROW 22 OVERLAP 58 AT TOR NEYS SEQUENTIAL DO B E THROW United States Patent Ofihce 3,098,141 ENCLOSED PRECISION SWITCH George Wintriss, Carversville, Pa. Filed Oct. 4, 1960, Ser. No. 60,378 7 Claims. (Cl. 200-159) This invention relates to electric switches and more especially to switches having contacts in a closed and sealed chamber.
It is an object of the invention to provide an improved electric switch having high capacity and much longer life than other switches. It is another object to provide an improved switch in which the contacts are enclosed in a sealed chamber filled with gas or liquid for eliminating or reducing any arcing of the switch contacts.
The invention is constructed so as to obtain silent, precision operation with a short stroke; and the parts are shaped and correlated in such a way that the invention may be used for extremely small switches. The sealed feature makes the switch explosion-proof.
Another object is to provide a switch, of the character indicated, in which the contacts are located in position to obtain sequential closing of the respective circuits of the switch. In the preferred construction, the contacts are leaf springs and the switch has a plunger consisting of a ball which wipes the contacts so as to maintain clean surfaces, and which rolls to some extent on the contacts so that different areas of the ball touch the contacts at different times. This maintains the surface of the ball in a clean condition and equalizes any wear over the surface of the ball. The switches of this invention are particularly suitable for automatic controls, for many industrial and domestic uses, in missiles and electronic apparatus requiring precision switching, sub and microrniniature switches, for either rotary switching or pushbutton switching.
Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.
In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views;
FIGURE 1 is a side elevation of a switch embodying this invention and made in capsule form;
FIGURE 2 is a greatly enlarged sectional view on the line 22 of FIGURE 1, but showing the switch installed in a holder;
FIGURE 3 is a sectional view on the line 3-3 of FIG- URE 2;
FIGURE 4 is a sectional view on the line 4-4 of FIG- URE 3;
FIGURE 5 is a diagrammatic, reduced-scale elevation of the switch and holder shown in FIGURES 2 and 3, and showing rotary cam means for operating the switch;
FIGURE 6 is a diagrammatic view of a modified form of the invention; and
FIGURES 7-10 are diagrammatic views showing modified forms of the invention.
FIGURE 1 shows a switch having a housing 10 made of electrical insulating material and with a metal shell 11 covering most of the outside of the housing 10. The contacts are enclosed in a chamber within the housing 10; and this chamber is closed and hermetically sealed in its upper end by a diaphragm 12. Conductors extend through the bottom of the housing 10 and have short extension portions 14 at the lower end of the housing 10 for connection with the circuits in which the switch is to be used.
The switch shown in FIGURE 1 is a unitary capsule construction which can be inserted into a socket of control equipment in which the switch is to be used. In the preferred construction there are lugs 16 extending from the shell 11 for holding the switch capsule in assembled 3 ,098,141 Patented July 16, 1963 relation with the structure into which it is inserted and there is another lug '17 which serves as a key.
FIGURE 2 shows a portion of the interior of the housing 10. There is a chamber 20 within the housing 10; and this chamber is preferably of generally cylindrical cross section but with channels along its inside wall for receiving leaf-spring conductors 22. It is these leaf-spring conductors 22 which extend through the bottom of the housing and which have the extensions 14 at their lower ends. For a portion of the height of the chamber 20, there is a center cup 24 which holds the spring conductors 22 securely clamped against the walls of the housing 10; and the cup 24, spring conductors 22 and housing 10 are integral so as to completely seal the lower end of the chamber 2%).
FEGURE 3 shows the way in which the extensions 14, at the lower end of the housing 10, extend radially outward and downwardly in channels 26 formed in the lower end of the housing 10 and providing clearance for the contact extensions 14. When unrestrained, these extensions 14 project some distance below the housing 10, as indicated in dotted lines, but they are resilient and are pressed upwardly into the channels 26 when the housing 10 is pushed down into a socket 30 in a holder 32. The key 17 fits into a keyway 31.
There are fixed conductors 34 in the bottom of the socket 30 for contact with the extensions 14 of the switch capsule. Each of these conductors 34 extends upwardly in the holder 32 and then outwardly into a recess 38 at the upper part of the holder 32. A terminal screw 40 in each of the recesses 38 extends through the conductor 34 and clamps a wire 42 to the conductor 34 for joining the conductor with an external circuit. Only one of the recesses 38 and terminal screws 40 are shown in FIG- UR 3 but it will be understood that there are others at different locations around the switch capsule, as indicated in FIGURE 2.
In the construction shown in FIGURES 2 and 3 there are four spring conductors 22 and corresponding terminal screws 46; and there is also a center contact 46 in the bottom of the cup 24. A special contact and conductor 50, in the bottom of the socket 30, is provided for connecting the center contact 46 with an external circuit, and is an extension of one of the conductors 34.
The switch has a plunger consisting of a metal ball 54 supported by a. circular upper end portion 56 of a spring 58. The lower end of this spring 58 extends across and touches the inner end of the center contact 46. Thus there is always a circuit between the ball 54 and the center contact 46.
The upper portion of the chamber 20 is of larger diameter than the outside diameter of the cup 24. This provides clearance behind the spring conductors 22 so that they can be displaced radially outward from the positions shown in FIG RE 3. The diameter of the ball 54 is slightly greater than the distance between the spring conductors 22. Downward movement of the ball 24, therefore, causes the ball to touch the spring conductors 22 and to bend them outwardly. The resistance of the spring conductors 22 to bending provides pressure be tween them and the surface of the ball with which they contact. The upper ends of the spring conductors are preferably shaped to provide them with concave faces having radii of curvature substantially equal to the radius of the ball 54. These concave faces provide movable contacts 62 of the switch.
If the switch is to be used for opening a circuit as the ball 54 is depressed, then the contacts at the upper ends of the spring conductors 22 must be shaped as shown in FIGURE 6. A normally-closed circuit, which is to be opened by downward movement of the ball 54, is pro vided with a contact 63 which projects radially inward from the spring conductor 22 at an elevation which is above the maximum diameter of the ball 54 and out of contact with the ball when the ball is displaced downwardly into the dotted-line position shown in FIGURE 6. The inner face of the spring conductor 22 below the contact 63 is preferably covered with electrical insulating material 63a so that displacement of the ball into contact with the spring conductor 22 below the contact 63 can not close the circuit. Various combinations of single-pole, double-throw switch effects, with and without overlap of the closing of the circuits, can be obtained by having contact surfaces 63 of different lengths along the spring conductors 22 and at different elevations relative to one another.
At the upper end of the switch capsule there is a diaphragm 12. This diaphragm is made of flexible material such as a plastic material having physical and dielectric strength, thermal range and chemical resistance, similar to polyesters, synthetic rubbers, polychemicals or fluorocarbons.
The diaphragm 12 has a bead 66 around its circumferential edge and this bead 66 is held in place by a rolled-over edge 68 at the upper end of the shell 11. The diaphragm 12 is bonded to the shell 11 by cement, or in any other suitable manner. This construction with the bead 66 and rolled-over edge 68 is merely representative of a hermetic seal between the circumference of the diaphragm 64 and the metal shell or housing of the switch.
The height to which the ball 54 is raised by the spring 58 is limited by the diaphragm 12. The switch can be made so that the ball is above all of the contacts 62 when in its fully raised position. With such a construction, the circuits of all of the spring conductors 22 are open. In the construction illustrated, however, the left-hand spring conductor 22 is made high enough so as always to touch the ball 54. This gives the switch a normally-closed circuit from the left-hand spring conductor 22 to the ball 54 and through the spring 58 to the center contact 46. If the switch capsule is made without any center contact 46, and a normally-closed circuit is desired, then two of the spring conductors 22 can be made high enough always to touch the ball 54.
In the preferred construction, the posite spring conductors 22 are always made of difierent height so that when the ball 54 touches the higher one of the spring, conductors 22, it will tend to pivot about that point of contact as it moves downwardly into position to touch the oppositespring conductor 22. This causes a rolling action of the ball 54 which wipes the contacts 62 and which also causes different areas of the ball to touch the contacts 62 on successive operations of the switch. This equalizes any wear of the surface of the ball 54.
The shell 11 has small lugs 16, which may be made of material displaced from the metal of the shell 11, and which extend outwardly beyond the edge of the socket 30. A cover 76 fits over the holder 32 and has an opening for receiving the upper end of the shell 11. This cover 76 fits snugly around the outside of the shell 11 and holds the lugs 16 down against the holder 32 to keep the switch unit pressed down in the socket 30. The cover 76 has recesses providing clearances for the lugs 16, but this clearance may be provided in the holder 32, if desired;
The cover 76 extends across the recesses 38, and is secu-red to the holder 32 by screws 80 extending through openings in the cover 76 and threading into sockets in the holder 32.
FIGURE 5 shows the holder 32 mounted in position that disposes the switch with its longitudinal axis in a horizontal position. The center portion of the concave diaphragm 64 is in the path of rises 90 and 91 on a cam 92. As the cam .92 is turned counter clockwise, the rise 90 first displaces the diaphragm 64 toward the left in FIGURE 5 to operate the switch, and as the cam is turned further, the rise 92 causes turther dis]? diametrically opof the diaphragm 64 to operate other contacts within the switch. The cam 92 may be oscillated back and forth or rotated in one direction depending upon the desired sequence of operation. A single rise is used when the switch has only one displaced operating position.
From the description it will be apparent that the switch can be made with a normally-closed circuit which is opened by the cam 92, or with a normally-open circuit which is closed each time the cam 92 displaces the diaphragm, or with both kinds :of circuits as will be described for FIGURE 9.
It will also be apparent that the switch can be made to operate different circuits by having the necessary number of spring conductors 22 (FIGURES 2 and 3) around the inside wall of the housing 10; and that these circuits can be closed simultaneously or in sequence, depending upon .the length of the respective spring conductors.
FIGURE 7 shows a modified form of the invention which is in effect a single pole, single throw switch in which the ball 54 touches contacts 62 at the upper ends of leaf spring conductors 22. The contacts 62 are at the same level.
FIGURE 8 shows a modified construction in which the left-hand conductor 22 has a contact 96 extending to a higher level than the contact 6-2 at the right-hand conductor 62. In FIGURE 8 the spring 58 is part of the circuit, and as the ball 54 moves downwardly in position to touch the contact 96, a circuit is established between that contact and the contact 46 at the bottom of the housing.
As the ball 54 continues its downward movement, a second circuit is established when the ball touches the contact 62. The contact 96 is long enough so that the ball touches it during the entire downward movement of the ball. This switch of FIGURE 8 gives sequential operation.
FIGURE 9 shows a construction in which the switch is in effect a double-throw switch. With the hall 54 in its uppermost position, it touches the contact 62 on the left-hand conductor 22 and establishes a circuit through the spring 58. As the ball 58 moves downwardly, it moves away from the contact 62 at the upper end of the conductor 22 and touches the contact 62 of the right-hand conductor 22 thus establishing an alternate circuit with the spring 58.
FIGURE 10 shows a modification of shown in FIGURE 9. Long contacts 98 are used on both of the leaf spring conductors 22 so that the ball 54 continues to touch contact 98 on the left-hand conductor 22 for at least a portion of its travel after having moved downwardly far enough to also touch the contact 98 on the right-hand conductor 22.
The preferred construction of the invention has been illustrated and described, but changes and modifications can be made and some features can be used in different combinations without departing from the invention as defined in the claims.
1. A switch including a housing enclosing a chamber with resilient contacts confronting one another across the chamber, a plunger moveable axially in the chamber into an out of con-tact with said contacts, the contacts being positioned axially in the chamber so that. the plunger touches one before it touches the other during its axial movement toward the contacts, said plunger being loose and rotatable in the chamber about an .axis on which it is turned by friction against one contact before touching the other contact whereby contacting areas of the plunger are diiferent for successive operations of the switch, the plunger being a ball, and the switch including also a helical spring holding the ball at one end of the chamber, said resilient contacts being leaf springs of different lengths.
Q. The switch described the construction in claim 1, and in which there touch the ball when the is an upper contact in position to ball is in its uppermost position.
3. The switch described in claim 1, and in which the ball is movable through a stroke long enough to move away from said upper contact, and there is a diaphragm closing the chamber above the ball, and the upper contact is below the lowermost position of the diaphragm as said diaphragm depresses the ball.
4. The switch described in claim 2, and in which the contacts are the upper ends of leaf springs that serve as conductors and that extend lengthwise along the sides of the chamber, and the leaf spring for the upper contact has electrical insulation on a face that confronts the ball.
5. A switch including a housing enclosing a chamber that has a lower portion of reduced cross section and an upper portion of larger cross section, resilient conductors extending upwardly along the wall of the chamber where said chamber is of reduced cross section, the resilient conductors extending longitudinally into the upper portion of the chamber with clearance from the wall, and a center element in the lower portion of the chamber clamping the resilient conductors against the wall of the chamber, contacts at the upper ends of the conductors and confronting one another, and a plunger in the upper end of the chamber removable into position between the confronting contacts at the upper ends of the resilient conductors.
6. A switch including a housing enclosing a chamber that has a lower portion of reduced cross section and an upper portion of larger cross section, resilient conductors extending upwardly along the wall of the chamber where said chamber is of reduced cross section, the resilient conductors extending longitudinally into the upper portion of the chamber with clearance from the wall, and a center element in the lower portion of the chamber holding the resilient conductors against the wall of the chamber, contacts at the upper ends of the conductors, and a plunger in the upper end of the chamber removea-ble into position between the upper ends of the resilient conductors, the center element being a cup with its open end upward and its lower end closing the lower end of the housing, the plunger being a ball having a diameter larger than the spacing between confronting conductors on opposite sides of the chambers, and the switch including also a spring in the cup extending upwardly above the cup and holding the ball at a normally elevated position in the chamber above the level of at least some of the contacts.
7. The switch described in claim 6, and in which the cup is of electrical insulating material and it has a contact extending through its bottom wall, and the spring is made of metal and forms an electric circuit from the ball to said contact in the bottom of the cup.
References Cited in the file of this patent UNITED STATES PATENTS 1,215,423 Spangler Feb. 13, 1917 2,451,176 Schellman Oct. 12, 1948 2475696 Cornish July 12, 1949 2,526,061 Batcheller Oct. 17, 1950