GB1525233A - Temperature measurement apparatus - Google Patents

Abstract

1525233 Measuring temperature of engine part ROLLS-ROYCE MOTORS Ltd 22 Sept 1975 [31 Oct 1974] 47290/74 Heading GIN An apparatus for measuring the temperature of an engine part, e.g. a piston 1, while in cyclic motion comprises a series of thermocouples adapted to be embedded in the part, a plurality of contacts 25 arranged to move with the part and a plurality of fixed contacts 27 adapted to be disposed so that, in use, the first mentioned contacts 25 engage the fixed contacts 27 once during each cycle of the part. Means are provided for receiving the pulses produced by the repeated making and breaking of the two sets of contacts and for determining the temperature of the thermocouples therefrom. The contacts of each set of contacts may be mounted in one or two straight rows Figs. 3 and 4 (not shown), the fixed contacts 27 being pre-loaded against the carrier thereof. The fixed contacts may be of berylium copper with the carriers of the contacts being of an insulating material, e.g. a epoxide laminate. The contacts may all be silver tipped. Intermediate contacts in a row are each connected to two adjacent thermocouples Fig. 6B (not shown). The hot junction of each thermocouple is housed within a threaded member Fig. 5 (not shown) the member being in turn housed within a tapped bore in the piston Fig. 1 (not shown). The cones of the thermocouple are sheathed and mineral insulated. The fixed contacts are connected to the pulse receiving means Fig. 7 (not shown) which comprises a scanner for successively reading the pulses at the contacts and a digital channel display inductor associated with the scanner indicates which thermocouple is being scanned or monitored at any given time. A compensation signal corresponding to the temperature of the cold junction of the thermocouples which are situated, in use, remote from the engine, is fed into the scanner so that the true temperature measured by the thermocouples may eventually be recorded. The signals from the scanner pass to a sample and hold circuit, the output of which is a D.C. signal. The D.C. signal enters an amplifier and linearizor unit, the signal from the unit being used to drive a digital meter to display the temperatures of the thermocouples directly in degrees centigrade. The signal from the unit may also be used to drive a chart recorder or analogue meter. The scanner may be controlled by a datelogging system.