Spring Contact Assembly

1. Field of the Invention

This invention relates to spring electric contact assemblies in which a resilient spring having a contact at a free end projects from an insulating body member in which it is anchored.

2. Prior Art

Spring contact devices, particularly relay devices, which utilize a movable contact spring which is secured at one end to a substantially rigid spring carrier or mounting member and which has a free end carried contact which is biased towards an opposed fixed contact and wherein the spring carrying member is angularly secured in guide slots of an insulated body are known to the art.

A contact spring arrangment of this type is shown in U.S. Pat. No. 3,819,896 wherein a contact spring carrier is utilized which is clamped in an insulating body in an L-shaped configuration with respect to the spring with the spring projecting therefrom. This type of construction allows a considerable actual contact spring free length while at the same time providing a good seat in the insulating body.

However, with the typical prior art construction, above described, the length of the spring necessitates laterally supporting the contact springs on an abuttment of the insulating body in order to produce the requisite bias force. In the known arrangement, the abuttment is formed by a protrusion of the insulating body and the bias bend of the contact spring rests on the protrusion. This has the disadvantage that variations in dimensioning of the insulating body with regard to the support wall or in the dimensioning of the spring receiving slot in the insulating body or in the spring itself can all accumulate unfavorably to the final construction. This in turn can result in a corresponding variance in the contact force at the contact end of the spring. Particularly, at high temperature loads, the danger exists that the insulating body support point will become deformed and that the spring force at the contact will thereby alter. This possibility of variance in contact force must therefore be taken into account in the design of the contact actuator system so that, for example, for safety reasons, the selected contact response actuation perameters must be designed higher than desired.

It is therefore the object of this invention to design a contact spring arrangement of the type above described in a manner that assures a low variance of contact spring force without imposing high critical accuracy demands in production. However, at the same time, it is desired to maintain the greatest possible free spring length. According to the teachings of our invention, these objects are obtained by utilizing a substantially rigid spring carrier attached to the spring on the side of the spring opposite the contact, the carrier forming a support or fulcrum edge for the contact spring at a right angle to the longitudinal extension of the spring.

A spring assembly constructed according to the teachings of this invention utilizing the herein disclosed spring carrier is, therefore, provided with both a stable support in the insulation body and a desired spring length. The contact spring is secured to the spring carrier adjacent one edge thereof, the spring carrier being preferably formed as a stable or substantially rigid plate member. The spring rests on a parallel edge of the spring carrier opposite the attachment edge with the spring extending approximately parallel to the major alignment of the spring carrier plate. Thus, in operation, the spring is freely mobile over the length of the plate and, therefore, can also be bent outwardly with respect to the plate. The fact that the contact spring is carried by and supported by its associated spring carrier insures a directionally stable, good, seat, which results in a very low variance of contact spring force. Particularly, even at high temperatures, the aforementioned danger of deformation of the spring support or fulcrum and its associated variance in contact force, is avoided.

Additionally, by utilizing this construction, an important added benefit is obtained. It is possible to eliminate the previously used expensive hardened resin or duo plastic insulator body and to replace it with a cheaper thermoplastic or unhardened resin insulator body an example of a insulator body is shown in U.S. Pat. No. 3,824,511 to Aidn et al issued July 16, 1974. Further, the substantially rigid spring carrier not only provides support for the spring during operation, but also provides protection during assembly of the contact spring device. By projecting a top side of the spring carrier beyond the insulating body, an abuttment face is therefore provided which can be used to firmly press the spring and spring carrier unit into the plastic insulating body without thereby endangering the more delicate precisely biased spring member.

The totality of reduction achieve in the contact force variance from the prior art provides a corresponding reduction in the angular deviation necessary for accurately positioning the contact end of the spring. These factors produce a more favorable force-path characteristic with a lower response exitation and a greater production reliability while maintaining a corresponding reduction in production cost.

In the preferred embodiment of this invention both the contact spring and the spring carrier are enclamped in a common slot in the insulating body. In the region of the common enclampment point, the contact spring is connected to the spring carrier by spot welding. Also, in the preferred embodiment shown, the contact spring is provided with a peaked protrusion or roof shaped bend in the area of the clamping point. Thus, the spring, together with the spring carrier, will be safely enclamped in the guide slot of the insulating body. Additionally, the spring carrier itself is expediently clamped in a further portion of the guide slot, which runs parallel to the contact spring, spaced from the common clamping point, by a bent over lug portion of the spring carrier. Additionally, it is advantageous if the spring carrier abuts its side opposite the contact spring against a support surface of the insulating body in areas other than the enclampment point. This provides for increased rigidity and directional stability without in any way limiting mobility of the contact spring.

It is therefore an object of this invention to provide an improved contact spring arrangement wherein the contact spring is affixed to a spring carrier which is received in an insulating body in a somewhat L-shaped manner, the spring carrier providing a fulcrum point for the contact spring.

It is another and more particular object of this invention to provide a contact spring arrangement wherein the spring which has a contact adjacent one end is affixed to a spring carrier adjacent its opposite end, the spring carrier comprising a plate-like member extending parallel to the spring for a portion for a length of the spring and having an edge intermediate the point of attachment of the spring and the contact end of the spring which functions as a fulcrum point for the spring, the contact spring and spring carrier being commonly received in a slot in an insulation body.

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 modification may be effected without departing form the spirit and scope of the novel concepts of the disclosure, and in which:

FIG. 1 is a fragmentary cross sectional view of a contact spring assembly constructed according to this invention.

FIG. 2 is a fragmentary cross sectional view of the assembly of FIG. 1 taken along the lines II--II of FIG. 1.

FIG. 3 is a fragmentary cross sectional view taken along the lines III--III of FIG. 1.

FIG. 4 is a fragmentary vertical cross sectional view taken along the lines IV--IV of FIG. 1.

FIG. 5 is a fragmentary plan view of the spring carrier according to this invention, illustrating, by shaded sections, contact surfaces with the insulating body.

The contact spring arrangement of our invention, as shown in FIGS. 1 to 5, includes a contact spring 5 and spring carrier 4 in an insulating body 1. The spring and spring carrier are received, preferably, in guide slots 2 and 3 which are aligned with one another. The spring carrier 4 is basically plate shaped and a resilient movable contact spring 5 is secured thereto. The spring is biased by a biasing bend 6 towards a fixed counter contact carrier 7 which is also mounted in the insulating body. The contact spring 5 can be operated by a slide member 8 or the like.

In the area of enclampment of the contact spring and spring carrier in the guide slot 2, the contact spring 5 is attached to the spring carrier 4, as by means of welding spots 9 or the like. Otherwise the contact spring runs approximately parallel to the plate shaped spring carrier and is free to move relative thereto. An edge 10, of the contact spring carrier, parallel to and opposed, to an edge forming the back of the spring carrier adjacent to the point of attachment, forms a fulcrum point for the spring. The edge 10 lies intermediate the dimensioning of the insulating body and therefore, the spring carrier is also pressed into the insulating body at the point of the edge 10. Because the contact spring is attached to its own spring carrier it exhibits good stability without its mobility being limited. This is graphically illustrated, for example, in FIG. 2, with respect to the contact spring 15 which is currently being operated by the slide 8. This spring is secured to the spring carrier 14 and engages the spring carrier edge 16. That portion of the spring intermediate the point of fixation of the spring to the spring carrier and the edge 16, if free to curve outwardly in the region 17 away from the spring carrier. This allows exploitation of the large effective spring length thereby allowing the contacts to be spaced considerably from the attachment portion of the insulating body. In such a manner, the force-path characteristic of the spring is optimized.

To improve the seating of the spring carrier 4 and the contact spring 5 in the guide slot 2, the contact spring is provided with a protrusion 11, which is preferably peaked in the manner of a triangular roof section. Thus, the spring carrier is pressed into the insulating body 1 with one side of the spring carrier, in contact with the insulating body. In order to maintain this forcing of the spring carrier to one side of the slot, a lug 12 projects forwardly of the edge 10 into the aligned guide slot 3 and is bent, as shown in FIG. 3 to urge the main portion of the spring carrier into bearing contact with the insulating body. The lug 12 is therefore effective, especially when combined with the peak 11, to press the spring carrier against bearing surfaces of the insulating body. The areas of contact of the spring carrier against the insulating body are illustrated as the shaded areas of FIG. 5. This provides the spring carrier with both good rigidity and directional stability so as to properly support and maintain the contact spring.

Additionally, the spring carrier preferably has a height greater than the depth of the slot in the insulation block. Therefore, during installation of the spring and spring carrier into the insulated body, the unit may be gripped by an insulating tool at the projecting end face 18 and pressed into the guide slots 2 and 3. Thus the end face 18 provides an abuttment face to aid in installation without in any way damaging the spring. Subsequent to pressing the unit into the slots, the lug 19, with attached wings 20 is twisted to seat the unit. During this activity, the end face 18 can serve as a counter support.

It can therefore be seen from the above that our invention provides a spring contact assembly wherein the individual contact springs have a contact adjacent a longitudinal free end thereof. The inner or opposite longitudinal end is affixed to a plate shaped spring carrier. The spring carrier has a length running parallel to the length of the spring for a portion thereof and provides a fulcrum edge for the spring intermediate the ends of the spring. The combination of the contact spring and the spring carrier is inserted in a slot in an insulating body with the spring carrier being urged against one wall of the slot whereby the spring free to move within the slot.

Although the teachings of our invention have herein been discussed with reference to specific theories and embodiments, it is to be understood that these are by way of illustration only and that others may wish to utilize our invention in different designs or applications.