GB514568A - Improvements in or relating to temperature compensating devices for measuring instruments - Google Patents

Abstract

514,568. Temperature compensating devices. BENDIX AVIATION CORPORATION. May 10, 1938. No. 13960. Convention date, May 21, 1937. [Class 106 (ii)] An indicating or measuring instrument comprises a sensitive element connected by a motion transmitting mechanism to an indicating member wherein a temperature responsive element forming part of the motion transmitting mechanism is fastened at one end for rotative adjustment about its own axis and is free at its other end. In the pressure gauge shown in Fig. 1, a diaphragm 27 receiving the pressure to be measured from an opening 26 carries a post 29 in which is mounted a bimetallic rod 30 capable of being rotated on its own axis by an upturned end 30a (not shown) and held in adjusted position by a screw 31. The rod 30 is mounted parallel to a rockshaft 32 which it rocks on movement of the diaphragm by engaging a rod 39 radially connected to the shaft 32. Another radial rod 40 on the shaft 32 engages a rod 42 which rotates a sector 45 on a shaft 44 to rotate a pinion 46. and hence a needle 18 over a dial 17. On change of temperature, the diaphragm moves. but the bimetallic rod 30 'flexes, thus altering the leverage on the rod 39, and by rotating the rod 30 through its upturned end 30a so that the flexing occurs in the right direction and to the right amount, compensation for temperature is effected. In the modification shown in Fig. 7, the diaphragm 27 carries a rod 59 which engages a notch 58 in a bimetallic strip 50 mounted for rotation in a post 54 and held by a screw 56, the effective length of the strip being capable of variation by setting a screw 57 in any one of a number of holes in the rockshaft 32 to engage a corresponding hole in the strip 50. The rockshaft carries a radial arm 40 as in Fig. 1. Change of temperature causes the strip to flex and so to alter the leverage of the rod 59 about the rockshaft 32. The amount of flexure depends on the angular position and effective length of the strip.