GB482294A - Improvements in or relating to apparatus for measuring, indicating and/or recording a value which is a function of differential pressure - Google Patents

Abstract

482,294. Indicating and recording apparatus. ASKANIA-WERKE AKT.-GES. VORM. CENTRALWERKSTATT DESSAU UND C. BAMBERG-FRIEDENAU. Sept. 25, 1936, No. 26117. Convention date, Sept. 25, 1935. [Class 106 (iv)] [Also in Group XXIX] Apparatus for measuring, indicating, and /or recording a value which is a function of differential pressure especially when variations of such pressure are consequent on the variations of the rate of flow of a fluid or the translational speed of a vehicle, of the kind including a relay provided with a follow-up gear, the displacement of a member of which serves as a measure of said differential pressure, said follow-up gear including a loading device following a square law and acting in opposition to the pressure so that an evenly divided scale may be employed, has a linearly movable cam actuated by a screw included in the followup train. The Figure shows the invention applied to the indication of the flow in a conduit. Opposed diaphragms 15, 16 acted on by pressures derived from Pitot tubes 11, 13 arranged in the conduit 10, actuate a lever 20 provided with adjustable stops 21, 22 and coupled by a strut 25 with a three-armed lever 24. This lever which is counterweighted at 31 acts through an adjustable roller 29 on a bell-crank lever 30 to operate a swinging jet tube 28 so as to direct fluid arriving by the conduit 32 into one or other of the tubes 33, 34 leading to a reversible rotary fluid motor 35. This motor rotates a screw 36 carrying a traversing nut 39 fitted with pointers adapted to co-operate with a fixed scale 51 and a clockwork driven recording drum 53. The nut 39 also carries an arm 40 fitted with an adjustable wedge surface adapted to co-operate with a pin 42 on a bell-crank lever 43, one arm of which is connected by a spring 45 with the third arm of the lever 24 while the other arm is loaded by a spring 49 anchored to a fixed point. As the nut moves upward the tension of the spring 45 is increased and the effective radius at which it acts is increased at the same time. The springs 45 and 49 first act together in pressing the pin 42 against the wedge, afterwards the spring 49 opposes the spring 45 so assuring substantially constant contact pressure between the pin and wedge surface.