FIELD OF THE INVENTION

The present invention relates to a measuring element and, more particularly, to a measuring element for measuring forces

BACKGROUND

The measurement of relatively small forces, which typically act perpendicularly onto a material, is in many technical fields an important issue in order to be able to make appropriate statements regarding the material point concerned and/or the component exerting the force. An important field of application in this respect is the ascertaining of contact forces in many types of connections, for instance plug connections, in which an electrical and mechanical contact is typically produced by a contact pin or the like being loaded with a substantially perpendicularly-acting force which is generated by a complementary contact element. The elastic force which arises thereby has the function of producing and maintaining a reliable electrical contact between the two surfaces which are in contact. The contact force applied thereby should be both sufficiently large in order to produce, at the envisaged position, a relatively planar contact between the two contact surfaces and thereby to remove possible impurities, deposits and the like, so that a contact with as low a resistance as possible is formed. On the other hand, the contact force applied should not be too large, because in that case relatively large forces are required during the deflection of the component exerting the contact force and in particular excessive wear on the contact surfaces can also occur in the event of repeated plugging-together and decoupling of the corresponding components. However, a minimal contact force must be upheld in order to repeatedly provide the desired electrical and mechanical connection during the entire duration of the contact.

In order to therefore ascertain and also monitor the corresponding occurring contact forces, measuring elements or measuring transformers are employed which, for example, take over the role of a contact element, for instance a plug, and which are connected to the complementary plug device which is to be examined. In some known systems as described by way of example in German Patent Application No. DE 10 2011 054 319 A1, a measuring arm is used which, at given positions which come into contact with the complementary component, is equipped with a measuring cell which can output a corresponding signal when loaded with a force. In other words, in these known systems, the measuring cell which is provided for example in the form of a piezoresistive material or the like, is located precisely at the point at which a contact with the surface of the complementary component is produced, meaning that a more or less direct registering of the resulting normal force is possible. A relatively exact correspondence between the registered force and the forces actually occurring between a plug connection arises only if the entire structure of the measuring arm, including the measuring cell, is modelled as identically as possible on the geometry of the corresponding point in the component to be examined, because otherwise in the event of diverging geometry there arises a force which does not correspond to the actual conditions. Furthermore, the direct contact between the measuring cell and the complementary region of the plug connection can lead to increased wear on the measuring cell, particularly if frequent measurements are carried out in order to economically exploit the measuring system efficiently. In order to keep the degree of wear low, a suitable coating is typically applied in order to increase the mechanical strength of the measuring cell. However, through the application of an appropriate mechanical or more robust coating the response sensitivity of the measuring cell and thus the exactness and the resolution of the measurement results obtained is possibly reduced.

In other known measuring systems, an “indirect” registering of the forces is carried out by a suitably formed pair of measuring arms that, in terms of their geometry and material characteristics, can be modelled to a large extent on the actual conditions. The measuring arms enable a relative deflection relative to one another which is then detected at a suitable point of the measuring system. German Patent No. DE 25 56 836, for example, describes a measuring element and a measuring head for measuring small forces, in particular contact spring forces, wherein the measuring element consists of a one-piece plate which has two legs formed by slots that are connected to one another via a short web. On the short web and at the adjacent rigid regions there is formed a strain gauge from which one part is thus deformed by the spring force exerted onto the legs due to the deformation of the short web and thus can output a signal which is proportional to this deformation. Due to the two legs which are separated by a slot, the connecting web is for instance of the size of the slot and the strain gauge has an extent which is substantially greater than the web connecting the two legs.

The conventional systems described above permit an efficient ascertainment of spring forces in a correspondingly limited measurement range, but with the response sensitivity and the resolution and measurement exactness possibly being relatively low in the “directly” measuring system due to the structure of the measuring cell and, in the event of frequently repeated measurement, there occurring, due to the unavoidable wear, a change in the overall geometry of the measuring cell which may not be noticed for a long time and which in turn has an influence on the forces ascertained.

The previously described “indirectly” measuring concept does allow a relative exact modelling of the actual conditions in the region of the measuring arms, i.e. the coupling between the corresponding plug connection can be modelled relatively realistically, but reduced measurement exactness must be expected due to the geometric configuration and the relatively long strain gauge.

SUMMARY

A measuring element for registering forces comprises a first measuring arm extending in a longitudinal direction of the measuring element, a second measuring arm extending in the longitudinal direction, a deformation section connecting the first measuring arm and the second measuring arm to one another in an elastically deformable manner, and a transformer unit arranged on a first side or a second side of the deformation section. The first measuring arm and the second measuring arm can be deflected relative to one another in a direction perpendicular to the longitudinal direction. The transformer unit responds to deformation and is situated fully within the deformation section.

