GB605194A - Improvements in effort measuring devices - Google Patents

Abstract

605,194. Dynamometers. OLAER PATENT CO., and COMPAGNIE GENERALE POUR L'EQUIPEMENT AERONAUTIQUE. July 27,1945, No. 16449. Convention date, Sept. 8, 1943. [Class 106 (ii)] An effort-measuring device comprises at least one piston and cylinder transforming the efforts to be measured into liquid pressure, characterised in that said cylinder receives, from a pump or other source of liquid under pressure, an addition of liquid intended to compensate for leakage and in that said piston and cylinder arrangement is devised in such manner as to provide a leakage which increases proportionally to the increase of the volume of liquid present in the apparatus. In Fig. 1 is shown the known type of torque-measuring device to which the invention is applied. The shaft of which the torque is to be measured carries a pinion 1 which gears with three planetwheels 2, 3 and 4 carried by a frame 5 rigid with the part to which the torque is being transmitted and gearing with an annular gearwheel 6 which is connected by the rods 7 to the pistons 8 which thus move in the pistons 9 in accordance with the movement of the wheel 6, i.e. in accordance with the torque transmitted. A pressure gauge 12 is in communication with the two cylinders 9 and so gives an indication of this torque, but due to leakage in the cylinders or friction between the pistons and cylinders the true value of the torque is not indicated. In the present invention, Fig. 2, at least one of the cylinders 9 has a triangular orifice, as shown, so that the leakage increases proportionally to the amount of liquid in the system which is being supplied with liquid at a constant rate by a pump 13. In this way the rate of leakage automatically adjusts itself to the rate of feed and the amount of liquid present in the hydraulic system and the reading on the pressure gauge is therefore a true indication of the torque. In another embodiment, not shown, the controlled leakage is obtained by providing one of the cylinders 9 with a frustoconical flaring portion instead of an orifice. If desired, a pressure accumulator may be used instead of a pump.