Asea Aktiebolag

Allmanna Svenska Elektriska Aktiebolaget

Sture Siby

Orvar Dahle

Jan O Nordvall

Ake Widehn

Ronald Grek

Bertil Hoffman

Nils-Ove Bielsten

Lars-Erik Lindback

Folke Von Knorring

Nils Ove Bielsten

Compensation for external and internal pressure variations in hermetically closed load cells is achieved using three parallel diaphragms vacuum-tightly attached between a force-transmitting member and a surrounding housing. An internal diaphragm is located adjacent the transducer space, a preferably equally large external diaphragm is located adjacent the atmospheric pressure, and an intermediate diaphragm is located therebetween, the intermediate diaphragm being considerably larger than the other two diaphragms. The space between the external diaphragm and the intermediate diaphragm is connected to the transducer space and the space between the internal diaphragm and the intermediate diaphragm is connected to the atmospheric pressure. Any difference between the pressure in the transducer space and the atmospheric pressure will cause forces with the same direction for the internal diaphragm and the external diaphragm but with the opposite direction for the intermediate diaphragm, and with a suitable area of the latter, therefore, an equilibrium of forces can be achieved independently of the pressure variations.

Pressure-compensating device in load cells

A pressure-sensing transducer which can be used to continuously measure the pressure in the cylinder of an internal combustion engine comprising a pressure-transmitting element which includes a generally tubular seat and a metallic plate which closes off a top end of the seat, an M-shaped force-transmitting member which spans across the top end of the seat, the outer legs of the M-shaped member being connected to opposite portions of the top end of the seat and the inner legs being connected to the center of the metallic plate, and a magnetoelastic force-sensing member connected between the outer legs of the M-shaped member, such that pressure-generated forces applied to the metallic plate from within the generally tubular seat are transformed into a tensile force acting on the force-sensing member in a direction perpendicular to the longitudinal axis through the generally tubular seat.

Pressure-sensing transducer

A transducer for magneto-elastic stress measurement is formed of a holder and a core of magneto-elastic material provided with coils to generate a flux in and sense flux alterations produced by stresses of the core. The core is formed of one or more plates firmly attached to the holder and designed to be attached to the measuring object. The core may consist of a single plate attached to the holder at four symmetrical points, or of a cross having four arms the ends of which are welded to a frame of magnetic material which is secured to the holder. The holder may also be in the form of a casing of magnetic material which protects the core and coils and serves as a magnetic return path for the fluxes. For applications where disturbing magnetic fields may occur in the measuring object, the casing is preferably made of non-magnetic material and provided with a frame of magnetic material as a return path for the flux.

Magneto-elastic transducer

A transducer including four pins arranged at the corners of a square and provided with exciting and sensing windings are fixed either to the surface of a body of magnetic material to measure stresses therein or to a plate of magnetic material fixed to the body where the body is of non-magnetic material or has undesirable magnetic characteristics.

Magnetoelastic transducer arrangement

In measuring mechanical stresses in an object of hardened and tempered steel with a magnetic transducer of the type which comprises a magnetizing circuit for generating a magnetic field in the object and a measuring circuit for sensing the changes in the magnetic field which occur in the object when it is subjected to mechanical forces, in order to reduce the creep of the measuring signal which occurs in the case of continuous feeding, the magnetizing circuit is energize with energy in the form of AC pulses of a pulse length between 20 and 120 milliseconds.

Method of energizing a magnetic stress transducer to reduce the creep of

A magnetoelastic shear force measuring means for measuring shear stresses in tubular axles, preferably in aircraft landing gear axles, comprises two shear stress transducers. Each transducer has one iron core with winding to generate a magnetic field in the measuring object and a second iron core with winding to sense the field alterations generated in the measuring object by shear stresses. The two transducers are combined to form a measuring unit which is inserted in the tubular axle. The windings on the cores of the transducers are connected in such a way that the shear signals are added and signals from any torsion occurring are subtracted from each other.

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Vasteras, Sweden

Sture Siby