FR2611078A1 - RETENTION DEVICE FOR AN ELECTRIC RESISTOR WITH A THIN FILM REALIZED IN THE FORM OF A WAFER - Google Patents

Abstract

IN KNOWN RETAINING DEVICES OF THIS KIND, THROUGH THEM, AN UNDESIRABLE HEAT DISSIPATION WHICH HAS THE EFFECT OF FALSE THE MEASUREMENT VALUES. THE MECHANICAL STRESSES ON THE SUPPORT OF THE THIN-FILM RESISTOR REDUCE ITS LIFETIME. TO REMEDY TO THESE DISADVANTAGES A PARALLEPIPEDIC RETAINER 4 IN THERMALLY INSULATING MATERIALS AND PROVIDED FOR EACH OF THE SMALL DIMENSIONS 3 OF THE SUPPORT 1 IS BUILT, BY AN APPROPRIATE ARRANGEMENT OF OBLIQUE PLANS 7 AND RECESSES 9 IN THE FORM OF A CORNER, PRODUCE A SELF-CENTERING EFFECT AND SUPPORT 1 IS RETAINED UNDER COMPRESSIVE EFFORTS. THE RETAINING DEVICE ACCORDING TO THE INVENTION IS APPLICABLE TO THIN FILM RESISTORS INTENDED TO MEASURE AIR MASSES IN THE INTAKE MANIFOLD OF INTERNAL COMBUSTION ENGINES.

Description

Retainer for thin film electrical resistance

  produced in the form of a wafer A retaining device of this kind for a thin film electrical resistance produced in the form of a wafer, which consists of a thin layer of metal on a rectangular electrically insulating support and is intended in particular to measure the mass of in the intake manifold of an internal combustion engine, the support being partially enclosed at each of

  its short sides by a retaining member so as to

  to put the support to a compression force, is known thanks to the German patent application published under the born 3328853. In this respect there is a problem which consists in that during the measurement of the air mass in the collector d intake of an internal combustion engine the measurement values are distorted because it is not only the flowing fluid which gives off heat from the

  metallic resistance electrically heated but equal to

  heat transmission via the sup-

  port to the retainer, so that the measured value

  re found distorted. The retaining member itself is fixed on a plate. When the assembly is subjected to DEM ME2 cushions caused by the engine, the resistance must be

  thin film and the electrical connection means con-

  due to the latter are substantially protected from bending forces. To this end, the retaining members exert on

  the support an initial compression tension.

  The object of the present invention is to obtain

  thermal decoupling of the resistance & cou-

  thin che and retainer by a mode of con-

  appropriate struction of the retaining member. This object is achieved according to the invention by the fact that the retaining member is formed of a parallelepiped made of thermally insulating material and whose side facing the support has a recessed region centrally, so that from from it extends on each side an oblique plane towards the front sides and that it is executed horizontally in each oblique plane, in order to receive the support, a wedge-shaped recess

  whose depth is constant with respect to the oblique plane

  that serving as a reference plane. An advantageous embodiment consists in that a projection is provided on

  the side of the parallelepiped opposite the recessed surface.

  The solution proposed by the present invention makes it possible to obtain very rapid establishment of the thermal equilibrium and to prevent the amount of heat released from being influenced by the retaining member, that is to say that the heat transfer remains constant throughout the

resistance life.

  An exemplary embodiment of the invention is shown in the accompanying drawing and described in more detail below. The thin-plate electrical resistance is applied as a metallic layer 2

  on a rectangular support 1. The support is fixed to the ni-

  calf on each of its short sides 3, by means of a retaining member produced in the form of a parallelepiped 4 and a fastener 5, to a plate not shown. The unique figure

  represents only half of the entire construction

  tion since the two sides are symmetrical. The parallel

  piped 4 is made of a thermally insulating material.

  It has on the side of the support 1 a recessed region produced in the form of the surface 6. From the surface 6 extend oblique planes 7 towards the sides

  frontal 8. In each oblique plane 7 is executed horizon-

  talement, in order to receive the support 1, a wedge-shaped recess 9 whose depth is constant relative

  in the respective oblique plane serving as a reference plane.

  On the side opposite surface 6 is provided on the

  parallelepiped 4 a projection 10 which fits into the

  spot 5. Since the fastener 5 consists of a strip of elastic sheet metal and that such a fastener is on

  each small side 3 of the support, the latter is assu

  jetti being subjected to an initial compression tension

  if we. If another arrangement is chosen and the

  5 fasteners would be removed, the compression force

  siré can be produced by a compression spring mounted

  behind one of the parallelepipeds 4.

  In the exemplary embodiment shown the electrical circuiting of the metal layer 2 is carried out

  by means of supply conductors not shown which pre-

  feel a soldering point on layer 2 and another

  brazing point on the clip 5. Thanks to a length ap-

  propriée conductors these are kept free of tensile forces so that the solder is not stressed even in the case of length variations of thermal origin or when the assembly is subjected to shaking. Thanks to the execution of two oblique planes 7 in each parallelepiped 4 and to the presence of the recesses 9

  in the form of a wedge in planes 7 there is a self-centered

  trage of the support 1 between the parallelepipeds and a

  thinking of dimensional deviations of the constituent elements as a result of the initial compression tension. The support

  1 is received in the recesses 9 in the form of a practical wedge

  only occasionally, so the contact surfaces are small and heat dissipation at this

level is minimal.

Claims (2)

  1 - Retaining device for an electrical resistance with a thin layer produced in the form of a wafer, which resistance consists of a thin layer of metal on an electrically insulating rectangular support and is intended in particular for the measurement of air masses in the collector engine intake & internal combustion, the support being partially enclosed on each of its short sides by a retaining member which subjects the support to a compressive stress, characterized in that the retaining member is formed of a parallelepiped (4) composed of thermally insulating material and whose side facing the support (1) has a region (6) recessed centrally, so that from the latter extends on each side an oblique plane ( 7) towards the front sides (8) and that in each oblique plane (7) is executed horizontally, in order to receive the support (1), a wedge-shaped recess (9) whose depth is constant with respect to the pl oblique year (7) serving as a plane reference.   2 - Device according to claim 1, character-   rised in that a projection (10) is provided on the side of the   parallelepiped (4) opposite the recessed surface (6).