GB209513A - Improvements in indicators for direct measurement of the mean pressure of the working fluid in piston engines - Google Patents

Abstract

209,513. Schimanek, E. Oct. 20, 1922. Steam - engine and like indicators.-Apparatus for measuring the mean pressure in a cylinder of an internal combustion or other piston engine comprises a piston 2 in a cylinder 1 which is connected at 9 to the engine cylinder to be tested, the pistons in the two cylinders being driven svnchronouslv. The gear for driving the indicator from the crank or valve shaft of the engine comprises an epicyclic train containing an element, adapted to be displaced to give an indication of the mean pressure. The crank shaft 4 of the indicator piston 2 is connected to the epicyclic gear 15, 18, 19 to a shaft 16 which is driven by the engine at suitable speed, and in order to obtain an indication of the effect of connecting the cylinder 1 to the engine, cylinder, the stud 20 of the planet pinion 19 is mounted on an arm 21 which may rock freely on a boss 13. One end of the arm is restrained by a tension spring 23, Fig. 2, attached to a fixed part 24, and the other end 26 bears on the rod of a diaphragm 27. The chamber 28 contains liquid and has a gauge 29 for indicating the pressure imparted by displacement of the arm 21. In use, the reading of the pressure gauge 29 is taken when the engine is stationary, and this is considered zero point. When the engine is working, and the cylinder 1 is connected to the engine, the pressure on the piston 2 will cause a displacement of the planet pinion 19, and of its arm 21, in the direction of the arrow 30, Fig. 3. An increase of pressure will be indicated on the gauge 29. In order to ascertain the deduction to be made from this increase to account for frictional losses, the cylinder 1 is opened to an atmospheric port 11 by turning the valve 6 and the reading of the gauge on the other side. of the zero is taken. The gauge may be calibrated to give direct readings in lbs. per square inch. In the arrangement described above the pistons in the indicator cylinder 1 and in the engine cylinder under test are shifted in phase as the arm 21 is rocked. Fig. 3 shows a modification for eliminating this alteration in phase. The chamber 28 containing the liquid which actuates the gauge 29 has a port 38 leading to a liquid supply tank 32 and a port 39 leading to an atmospheric discharge. These ports are controlled by a valve 34 actuated by the arm 21, the arrangement being such that an increase in pressure by the arm 21 results in liquid being allowed to enter from the tank 32 to reset the parts, and a reduction in pressure allows liquid to be exhausted for the same purpose. The tank 32 may he closed, and pressure obtained by compressing air into it. For the testing of multiple cylinder engines two or three pistons 2 working in suitably positioned cylinders 1 may be arranged around a common crank shaft 4. The shaft 16 may be driven by the engine through an epicyclic gear, the axis of the planetary pinion of which is variable in position so that the piston 2 may be synchronized with different pistons in the engine. In the arrangement shown in Fig. 8 the shaft 16 is driven by a gear 43, 44, 42, the planetary pinion of which is mounted on a stud carried by an arm 45 which may be varied in position. The cylinders of the multiple cylinder engine M have valve controlled pipes leading to a pipe 46 which connects at 9 with the cylinder 1. The valves 48 are mounted on a rod 49 which is turned by the setting arm 45 through sprocket and chain gearing 50, 51, 52 in order to select the cylinder to be tested in accordance with the engine piston which is in synchronism with the piston 2. To reduce its dimensions the flywheel 5 may be driven from its crankshaft 4 by gearing.