From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'The Mechanical Engineer' journal detailing an optical indicator for steam and gas engines.
Identifier | ExFiles\Box 79\3\ scan0094 | |
Date | 13th March 1914 | |
MARCH 13, 1914] THE MECHANICAL ENGINEER. 235 OPTICAL INDICATOR FOR STEAM AND GAS ENGINES. The apparatus shown in the accompanying cuts has been designed and patented by Prof. W. E.{Mr Elliott - Chief Engineer} Dalby, of the City and Guilds Engineering College, London, S.W., and William Watson, Assistant Professor of Physics, of the Imperial College of Science and Technology, South Kensington, London, S.W., for recording fluid pressure variations, and is particularly adapted to obtaining indicator diagrams from high-speed engines, such as internal-combustion engines. The indicator is of the type comprising a pair of mirrors, one of which is rotated about its axis by the movement of a diaphragm under the action of the fluid pressure, while the other is rotated about an axis at right angles to the former axis by a reciprocating part of the engine, records of the various fluid pressures being made upon a photographic plate, by means of a ray after reflection from both mirrors. In the arrangement under notice the necessary adjustment of the line corresponding to atmospheric pressure when the diaphragm is changed is effected by altering the position of the mirror, the position of the diaphragm being unaltered. There is also provided an adjustable stop at the back of the diaphragm, and means whereby accumulation of liquid in contact with the diaphragm is prevented. Any existing source of light can be made use of for obtaining a photographic record of the diagram. Referring to the illustrations, Fig. 1 is a sectional elevation of the apparatus, Fig. 2 is an end elevation, Fig. 3 is a sectional plan; while Figs. 4, 5, 6, 7, and 8 are detail views, showing devices for obtaining a suitable source of light for the production of the diagram. The whole of the indicating apparatus is mounted on a rigid baseplate A adapted to be securely fixed to the engine. The diaphragm B is placed in communication with the engine cylinder through the pipe C, and a stop D, adjustable by screwing relatively to the framework A, is provided at the back of the diaphragm, the stop being adapted to bear against the diaphragm along the circumference of a circle, and to be fixed in any given position by means of a set-screw. A water-cooling chamber F is provided in the neighbourhood of the diaphragm. The diaphragm is connected to the pivoted mirror G by means of a rod H, and in order to alter the adjustment of the line corresponding to a given pressure, such as atmospheric pressure, the mirror is moved relatively to the diaphragm by rotating the piece K by means of a tommy bar inserted into one of the apertures L. This piece K carries the mirror G, and its movement in the longitudinal direction relative to the rod H, which is held steady by the diaphragm, causes the mirror to tilt to give the necessary adjustment. A drain hole M is provided in the space in front of the diaphragm, this hole being normally closed by means of a screw which can be removed in order to remove oil or other liquid from the front of the diaphragm. The camera O is mounted on the apparatus so that it can be readily removed by loosening the catch screws P. A pivoted mirror Q is provided, actuated in any suitable manner from the piston of the engine, and in any desired phase relationship with the movement of the piston. The source of light may be any suitable existing source, and an image, for instance, of an electric arc may be obtained on one of the apertures N of the diaphragm plate S, by means of a prism T and lens U, mounted so as to be capable of rotation on the spindle V.{VIENNA} The aperture R may be varied as desired by means of a pivoted plate, carrying apertures, any one of which may be placed in the operative position. A fixed concave mirror Z may be provided in the neighbourhood of the mirror G, in order to give a datum line at any determined distance from the atmospheric line. The diaphragm plate S is carried by a tubular plate, and carries the holder for the lens and mirror T U. The operation of the apparatus is as follows: The lens and mirror T U are adjusted so as to give an image of the source of light on one of the apertures R.{Sir Henry Royce} This image is focussed by means of the concave mirror G, and the plane mirror Q, on to the ground glass of the camera, which is then replaced in the usual manner by a sensitive plate. The mirror Q is given a movement corresponding with the movement of the piston of the engine by any suitable means, the driving mechanism of the mirror including an epicyclic device, whereby the phase can be altered to give any desired difference in phase between the movement of the mirror and the movement of the piston of the engine. A diaphragm suitable to the pressures to be recorded is fitted into the apparatus, and the position of the mirror G adjusted by rotating the piece K by means of a tommy bar inserted in one of the apertures L. The pressure in the cylinder acts on the front of the diaphragm B causing this to tilt the mirror G in such a manner as to cause a spot of light to move on the ground glass or sensitive plate in the direction at right angles to the paper, Fig. 1. The motion of the mirror Q imparted from the engine piston or other reciprocating part of the engine causes the spot of light to move over the ground glass or sensitive plate in the direction parallel to the paper. It will thus be seen that the pressure diagram is produced on the ground glass or on the plate, corresponding with the pressures in the cylinder at different points of the stroke of the piston of the engine. In order to keep the diaphragm cool, water may be supplied continuously through the chamber F, and any condensation takes place in the front of the diaphragm, the condensed liquid can be removed through the aperture M by removing the screw. It will be seen that in order to remove the mirror it is only necessary to remove the camera O and withdraw the piece K outwards after the screw W has been slackened. The part K being withdrawn in the holder (see Figs. 1 and 3), carries with it the mirror and the rod H, leaving the diaphragm in position so that there is no need to stop the engine to remove the mirror. OPTICAL INDICATOR FOR STEAM AND GAS ENGINES. Institution of Electrical Engineers: Manchester Local Section. The next meeting will be held at Liverpool University on Tuesday, March 24th, when Mr. F.{Mr Friese} J.{Mr Johnson W.M.} Teago will read a paper entitled “Experiments on Air Blast Cooling of Transformers.” The equipment and apparatus for the measurement used in the experiments described in the paper will be in operation. | ||