US 3819896 A
Mounting for contact springs of an electrical switching device. The springs are mounted at their inner ends in an insulating base member for the switching device and are freely movable at their free ends to alternately engage or disengage a stationary contact upon operation of an actuator for the springs. The mounting for each spring includes a stable flexing leg extending across the inner end of the spring and mounted in the base for the switch and having a right-angled portion extending parallel to the spring and mounted in a right-angled portion of the base for the switch. The stable flexing leg has a terminal extending therefrom through a window in the right-angled portion of the base. The stationary contact is mounted to extend between the contact springs and is flexible to a limited extent and fixed to an extension of the insulating base at its rear end and along one side of said contact. The stationary contact is diagonally slit in a longitudinal direction along the support portion of the base extending parallel to the contact, to accommodate a limited flexing of said stationary contact and may be drilled to vary the flexibility thereof and provide the required elasticity of said contact, and determine the bending point thereof.
Claims available in
Description (OCR text may contain errors)
United States Patent Aidn et al.
[ June 25, 1974 ELECTRICAL SWITCHING DEVICE AND CONTACT SPRING SET THEREFOR Inventors: Martin Aidn; Alois Ruhland, both of Munich, Germany Assignee: Siemens AB, Berlin, Germany Filed: Apr. 12, 1973 US. Cl. 200/166 J, 200/1 A Int. Cl. I'I0lh l/28 Field of Search... 200/1 A, l R, 166 J, 166 CT;
References Cited UNITED STATES PATENTS 5/l946 Wood 200/1 A l/l95l Bellamy 200/l A X 7/1960 Hufnagel ZOO/i661 Primary Examiner-Robert K. Schaefer Assistant ExaminerWilliam J. Smith Attorney, Agent, or FirmHill, Gross, Simpson, Van Santcn, Steadman, Chiara & Simpson [5 7 ABSTRACT Mounting for contact springs of an electrical switching device. The springs are mounted at their inner ends in an insulating base member for the switching device and are freely movable at their free ends to alternately engage or disengage a stationary contact upon operation of an actuator for the springs. The mounting for each spring includes a stable flexing leg extending across the inner end of the spring and mounted in the base for the switch and having a right-angled portion extending parallel to the spring and mounted in a right-angled portion of the base for the switch. The stable flexing leg has a terminal extending therefrom through a window in the right-angled portion of the base. The stationary contact is mounted to extend between the contact springs and is flexible to a limited extent and fixed to an extension of the insulating base at its rear end and along one side of said contact. The stationary contact is diagonally slit in a longitudinal direction along the support portion of the base extending parallel to the contact, to accommodate a limited flexing of said stationary contact and may be drilled to vary the flexibility thereof and provide the required elasticity of said contact, and determine the bending point thereof.
9 Claims, 5 Drawing Figures lii ELECTRICAL SWITCHING DEVICE AND CONTACT SPRING SET THEREFOR FIELD OF THE INVENTION Contact spring set for electrical switching devices.
BACKGROUND, SUMMARY AND ADVANTAGES OF THE INVENTION In relays having contact spring sets arranged in layers, it has heretofore been necessary to insert a relatively large portion of the length of each individual contact spring in the insulation material of an insulating member or base for the relay, to prevent the influences at the soldering lugs or terminals of the individual springs from being transferred to the contact parts of the spring. This applies not only to contact springs in which the contact legs and soldering lugs or terminals run in the same direction, but also applies where the soldering lug and contact spring are at right angles with respect to each other. A contact spring set of this type is shown and described in DOS 2,016,903.
Due to the large clamping area required for the contact springs, such springs must be relatively long in order to achieve the necessary effective spring length. If, however, there is insufficient room in the relay housing for long contact springs, short contact springs with a large spring constant, must be used in their place, which require high operational forces.
Furthermore, in contact spring sets which are not in layers, and in which the individual springs are only inserted into slots in the insulation material or base member for the relay, the requirements as to the clamping length of the spring in the insulating material or base are no different than in the previously described contact spring applications. Where an effort is made to avoid this and the contact springs are not injected into the insulation, but are subsequently clamped into guiding slots, corresponding large guiding angles are required for achieving good directional stability. This applies to the type of contact spring described in DOS 2,038,879 in which the soldering lug runs at right angles to the contact leg. In this disclosure, in order to achieve a stable mounting for the contact springs, the soldering lug must also be anchored relatively deep in the insulation material or base, and has the effect of increasing the overall height of the relay, which in many cases, is undesirable.
By the present invention, we affix a contact spring to an insulation base in guiding slots of relatively low depth which serve as a stable mounting for the spring and attain this by providing at least two fixing edges for the contact spring in which at least one of these fixing edges forms a mounting for a leg which basically runs parallel to the freely movable contact spring.
By the use of a second fixing edge running generally parallel to the contact spring and spaced from one side thereof, the contact spring is given good directional stability and exact spacing from the base and also enables the spring structure to be adjustable. Moreover, with the mounting just described, the parts of the contact springs which serve for fixing the spring to its insulating base can be kept very small in the interest of a compact relay structure and the contact springs can have a relatively large, effective spring length with a resultant minimum error constant. Thus, unavoidable production tolerances cause minimum differences in the force required to operate the spring and thereby enable the contact spring to be operated by a relatively low operating force.
In accordance with a preferred embodiment of the invention, two fixing edges are provided for each contact spring which run at right angles to each other. This results in a generally L-shaped spring in which the separation between the fixing leg of the spring and the contact leg can be attained as by a deep cut or slot. The contact leg and the fixing leg of the contact spring can be made in one piece, although where the spring is made from thin spring material, the fixing part or leg may be made of a more stable material in a generally L-shaped form and riveted or otherwise secured to the contact spring, and extend across and to one side thereof. The fixing leg of the contact spring may also have a solder lug extending from one side thereof and running perpendicular to the contact spring.
A principal advantage of the present invention is the provision of a firm insulating mounting for a contact spring, taking up a minor portion of the length of the spring.
Another advantage of the invention is that where the fixing of the contact spring is in slots formed in the right-angled walls of a single insulating base, a firm holding of the fixing leg and contact spring is attained by the use of outwardly curved entrance walls within which the fixing edges of the spring extend.
A further advantage of the invention is that the flexibility of the contact spring, free from its fixing leg, is attained by a slot between the contact spring and fixing leg, one wall of which is parallel to the side wall of the contact spring and the other wall of which is at an angle and converges toward the contact spring to provide a desired bending point of the spring which may be weakened in cross section and may be increased or decreased in accordance with the requirements for flexibility of the contact spring for different switching conditions.
Other objects, features and advantages of the invention will be readily apparent from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary view in side elevation of a switch and contact spring arrangement constructed in accordance with the principles of the present invention with certain parts broken away.
FIG. 1A is a fragmentary enlarged sectional view taken substantially along line A-A of FIG. I, and illustrating the detailed structure of a clamping slot for one of the contact springs.
FIG. 2 is a fragmentary bottom plan view of the switching contact shown in FIG. 1, with certain parts broken away and with the clamping areas of the switching contact and its fixing leg shown by dotted sectional lines.
FIG. 3 is a view somewhat similar to FIG. 2, but showing a modified form of contact spring in which the contact spring and fixing leg are in one piece; and
FIG. 4 is a detail view looking at the stationary contact from the bottom thereof and showing the clamping areas by dotted sectional lines.
DESCRIPTION OF PREFERRED FORM OF INVENTION In FIG. 1 of the drawings, we have shown in side elevation a portion of an electrical switching device and contact spring set constructed in accordance with the principles of the present invention, and including a base member 1 made from insulating material having two vertically spaced insulating slots 2 formed therein for receiving and forming a mounting for the inner ends of contact springs 4. The base 1 has a central leg 1a extending between the contact springs 4 in the direction of said springs and having a generally U-shaped and widened outer end portion la, the legs of which form a mounting for an insulating member 17 having a slot 3 extending thereacross and forming a clamping area for receiving the rear end portion of an intermediate contact 5.
Each contact spring 4 extends along one side of a stable fixing leg 7 forming a mounting therefor and curves upwardly from the leg 7 to a peak engaging a stationary abutment 40 between the ends of the spring and gradually curves downwardly from said peak to the end of the contact spring, to form a flexible contact leg 6, shown in FIG. 2 as having a slot 60 extending along the central portion thereof and dividing the contact leg along its center to increase the flexibility thereof. Contacts 9 are riveted or otherwise secured to the inside of each contact leg 6 for engagement with contacts 9a riveted or otherwise secured to opposite sides of the stationary contact 5. The gradual converging of the contact leg from its opposite ends to a peak engaging the abutment 4a biases the individual contact springs to engage the movable contacts 9 with the generally stationary contacts 9a.
The contacts 9 are disengaged from the contacts 9a by operation of a rectilinearly movable shifter 8 having a lug 80 extending between the contact springs and movable in opposite directions to disengage the contacts 9 from the contacts 9a of one contact spring and accommodate the engagement of the contacts 9 of the other contact spring with the contacts 9a by the bias of the spring. The shifter 8 may be the armature of a solenoid. This provides an alternately operable switching device in which contacts can be alternately made and broken by a simple shifting operation.
The insulating base 1 may be made from any suitable insulating material and preferably may be made from a plastic insulating material, and is shown as having a back wall or end portion lb with a right-angled portion 10 projecting therefrom along the outsides of the contact springs 4 and contact legs 6 of said springs. The right-angled portion 10 may form a mounting for the abutments 4a, abutting the peaked portions of said springs, and biasing said contact springs to engage the contacts 9 thereof with the contacts 9a on opposite sides of the intermediate generally stationary contact 5.
Each contact spring 4, as shown in FIG. 2, is made from a thin spring current conducting material, which may be phosphor-bronze or any other suitable currentconducting, spring-like material and is welded or otherwise secured to a leg 70 of a fixing part 7 which with the contact spring 4 and leg 7a are anchored at their trailing ends in the slots 2, shown in FIG. 1A as having converging entering portions, converging to the slots 2 having clamping areas 10 extending therealong.
The fixing leg 7 for each contact spring anchored along its leg 7a in the slot 2 of the base 1, is generally L-shaped in cross section and has a right-angled leg 7b anchored in an anchoring or clamping area 11 of a right-angled portion 1c of the base, extending parallel to the contact spring 4. The right-angled leg 7b of the fixing leg 7 has a terminal 12 extending through the right-angled portion 10 and along the clamping area 11. The terminal 12 may serve as a soldering lug or as a connecting plug and extends through a window or apertured portion of the right-angled portion 1c. The terminal 12 may be secured to the right-angled portion 10 and anchoring area 11, against withdrawal in any suitable manner, which for example, may be by twisting of the terminal or molding the terminal within said wall to encapsulate the terminal in said wall.
A firm mounting for the contact spring 4 has thus been provided, enabling free flexing of the spring and positively mounting the spring in the base 1 at its extreme inner end portion, to enable the spring to have a relatively large effective spring length with a small error constant.
In FIG. 3 of the drawings, we have illustrated a modification of the invention in which each contact spring and fixing part 7 is in one piece and clamped in the slot 2 of the clamping surface 10 and in a similar slot in a right-angled portion 1c forming the clamping area 11 for a portion 1b extending along said fixing or clamping area 11. A terminal 12 extends outwardly from the portion 1b of the fixing area 11 of the arm lc, as in the form of the invention illustrated in FIG. 2. The longitudinal extending portion 7b of the fixing leg 7 and the clamping or fixing area 11 are separated from the contact spring 4 by a deep slot 13 formed by an angular cut diverging to the contact spring and a second cut extending along the edge of the contact spring.
The intermediate or stationary contact 5 carried in the slot 3 of the clamping area 17 is supported outwardly of the clamping area for the contact springs 4, adjacent the outer end of the base 1 in the slot 3 formed in the clamping area 17 and a similar slot formed in a right-angled clamping area 18 formed in a bracket 18a extending along the stationary contact for a greater portion of its length. As shown in FIGS. 1 and 4, the stationary contact 5 has a contact leg 14 with contacts 9a riveted to opposite sides thereof. The contact leg 14 is shorter than the spring leg 6 of the contact spring 4. Said contact 5 is diagonally slotted by a cut 15, with the right-angled surfaces of said contact fixed or clamped to the clamping areas 17 and 18 arranged in a generally L-shaped or right-angled form.
In order to assure a firm mounting of the contact 5 to the clamping areas 17 and 18, a lug or finger 19 is cut from the fixing-part 16 of the contact 5 and may be wedged in the slot 3.
The angular cut 15 in the contact 5 may determine the position of the desired bending point of the contact leg 14. A hole 20 may also be drilled through the contact 5 to increase the flexibility of said contact particularly along the bending point thereof. The position and size of the drilled hole may be varied in accordance with therequired bending point of the contact leg and flexibility thereof. At least two small holes may take the place of the large drilled hole 20 to accommodate the flexibility of the contact 5 and bending point to be readily adjusted.
The contact springs 4 and 5 have the common advantage that in addition to the right-angled clamping areas and 17 for the inner ends of the spring legs of respective contacts 4 and 5, second right-angled clamping areas 11 and 18 are provided for said respective contacts 4 and 5. With this clamping arrangement and the flexibility of the contacts relative to the clamping areas, the contacts are firmly held in position in the base and the exact positions of the contacts may be maintained where the contacts are carried in low depth clamping slots.
A variation of the L-shaped clamping of the contact figures, not shown herein, would be to have fixing or clamping grooves or areas running parallel to opposite sides of the clamping legs and separated by cuts, like the cuts 13 and 15, extending for portions of the length thereof.
We claim as our invention:
1. In an electrical switching device,
a contact spring set including at least one elongated contact spring having a contact adjacent its free end and a mounting leg extending to one side of said contact spring,
a relatively stationary flexible contact spring having a contact on its free end adapted to be engaged with the contact on the free end of said elongated contact spring,
means disengaging said contacts and accommodating engagement thereof by the bias of said elongated contact spring,
a one-piece insulating base and mounting for said contact spring and stationary contact,
said insulating base having separate right-angled clamping areas for said mounting legs of said elongated contact spring having clamping areas extending perpendicular to and generally parallel to the stationary and movable contacts and clamping the right-angled edges of said mounting leg for fixing said movable contact to said base and providing the flexibility of said movable contact to engage and disengage the contact thereon with the contact of said stationary contact.
2. The electrical switching device of claim 1, in which terminals extend from said mounting leg for said elongated contact spring through the portions of said insulating base forming the clamping areas extending generally parallel to said elongated and generally stationary contact spring sets.
3. The contact spring set of claim 1, in which the clamping areas of the mounting leg of the elongated contact spring are to one side thereof and are formed in one piece with the elongated contact spring.
4. The electrical switching device of claim 2, in which elongated contact springs are on each side of said stationary contact spring said stationary contact spring has contacts on opposite sides thereof to be alternately engaged by the contacts of said elongated contact springs and said one-piece insulating base forming a unitary mounting for said stationary contact spring and said elongated contact springs.
5. The electrical switching device of claim 4, in which the mounting legs for said elongated contact springs each have a stable L-shaped fixing part having a part secured to extend across the rear end of said contact spring, each mounting leg extending parallel to the elongated contact spring and having a terminal formed as a part thereof and extending outwardly of said base through the clamping area thereof.
6. The contact spring set of claim 5, in which the mounting leg for the stationary contact also has a terminal extending from its securing part through the clamping area of said base extending parallel to said elongated spring, and secured thereto.
7. The contact spring set of claim 6, in which the base has a clamping slot in advance of and between said clamping slots for said elongated contact spring and the stationary contact has a lug bent therefrom and wedged in said clamping slot in advance of said clamping slots for the elongated clamping springs.
8. The contact spring set of claim 6, in which the mounting leg for the movable elongated contact spring has an inclined slot extending therealong separating the elongated contact spring from the right-angled mounting leg of said contact, the inner end portion of which defines the bending point of said elongated movable contact spring.
9. The contact spring set of claim 8, in which the mounting leg for the elongated movable contact spring has a hole extending therethrough spaced from and cooperating with said inclined slot to define the bending point of said elongated movable contact spring.