Measuring and testing – Dynamometers – Responsive to torque
Patent
1995-09-12
1997-02-25
Chilcot, Richard
Measuring and testing
Dynamometers
Responsive to torque
73862321, G01N 300
Patent
active
056061374
DESCRIPTION:
BRIEF SUMMARY
RELATED APPLICATIONS
This application is a continuing application based on prior copending application PCT/GB95/00050, filed Jan. 11, 1995, the benefit of the priority of which under 35 U.S.C. .sctn.120 is hereby claimed.
This invention relates to optical torque sensors especially, but not exclusively, for incorporation in vehicles.
Our European Application No. 93300792.4 describes an optical torque sensor which incorporates an input and an output member, each member being associated with a disc-shaped mask of equi-angularly spaced apertures which moves angularly with the respective member. However, this type of torque sensor requires a high degree of optical alignment. When such an optical torque sensor is designed to compensate for misalignment of the two masks, two sets of signal detectors may have to be positioned at exactly 180.degree. opposite each other. Such optical alignment accuracy presents many difficulties to manufacturers of the sensors.
According to a first aspect of the present invention a torque sensor comprises emitter means, receiver means adapted to receive a signal, signal processing means adapted to receive an output signal from the receiver means, the output signal from the receiver means being dependant upon the signal which it receives, and further comprising an electromagnetic radiation transmitting medium which alters the direction of propagation of electromagnetic radiation propagating through the medium and which is defined by a generally cylindrical body, the body being adapted to be attached to both an input member and an output member of a torsion bar which is located on a central axis of the body, the extent to which the direction of propagation is altered being dependant upon the torque applied to the medium, and the signal processing means being adapted to process the output signal from the receiver means so as to produce a modified output signal indicative of the torque applied between the input and output members.
We therefore provide a torque sensor utilising electromagnetic radiation effects which is simple to manufacture and in which alignment difficulties are reduced or substantially eliminated.
Preferably, the body comprises a cylinder, and the emitter means and the receiver means are aligned opposite each other on a line parallel with the central axis of the cylinder such that a portion of the cylinder wall is positioned between the emitter means and the receiver means. The emitter means is preferably adapted to emit a signal beam of electromagnetic radiation and the receiver means is preferably adapted to receive this signal beam radiation.
The emitter means and the receiver means may be mounted in a housing. The housing preferably prevents any electromagnetic radiation other than signal beam radiation from reaching the receiver means.
The cylinder is preferably firmly secured to both the input and the output member, the two members being aligned on the central axis of the cylinder such that the input member lies perpendicularly to one end face of the cylinder and the output member lies perpendicularly to the other end face.
Preferably the cylinder medium acts as an electromagnetic waveguide which guides the emitted signal beam of radiation along a path between the emitter means and the receiver means. Preferably, when no torque is applied between the input and output members, the cylinder medium guides the emitted signal beam along a longitudinally straight path between the emitter means and the receiver means, parallel to the central axis of the cylinder. When torque is applied between the input and output members the cylinder medium is preferably subjected to the same torque which in turn twists the medium of the cylinder to alter the path along which the signal beam radiation is guided such that the direction of propagation of the signal beam radiation leaving the cylinder medium via the end face of the cylinder which is nearest to the receiver means is not the same as the direction of propagation of the signal beam radiation which entered the cylinder mediu
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Biegel Ronald L.
Chilcot Richard
Lucas Industries Public Limited Company
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