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).
Page from a publication describing the 'C.F.R.' knock-testing apparatus, detailing its engine, carburetor, and other systems.
| Identifier | ExFiles\Box 27a\4\ Scan065 | |
| Date | 1st November 1931 | |
| 86 REFINER AND NATURAL GASOLINE MANUFACTURER NOVEMBER, 1931 duced by a small direct-current generator belted to the pulley of the induction motor. The electric switches, meters, and gas cell of the bouncing-pin instrument are grouped on a panel at the side, and the whole assembly is mounted on a cast-iron base. This knock-testing apparatus is supplied complete by the Waukesha Motor Company, Waukesha, Wisconsin. ENGINE With regard to the engine, the aim of the detonation sub-committee has been to produce one which is reasonably comparable in cylinder size to conventional automobile engines, and which can be operated under conditions approximating those prevailing when the knock occurs in service. It is in order to get this result over the wide range of fuels which must be tested that the continuously variable-compression type of engine was settled upon. Automobile engines are not variable-compression engines, of course; but different engines differ considerably both in compression ratio and in compression pressure; and, in general, automobile engines do not knock except when the throttle is substantially wide open. It was in order to approximate these conditions of service with the whole range of fuels which need to be tested, and to do so conveniently, that the continuously variable-compression engine was adopted. Variation of compression ratio, coupled with operation at substantially wide-open throttle, could have been secured by a somewhat simpler engine provided with a series of cylinder heads, of course; but changing cylinder heads is a time-consuming operation that over the period of life of the engine could well cost much more than the small amount represented by the difference in cost between the so-called fixed-compression engine and the more desirable engine of continuously variable compression. FIGURE 1 Front View of “C. F.{Mr Friese} R.{Sir Henry Royce}” Knock-Testing Apparatus FIGURE 2 Rear View of “C. F.{Mr Friese} R.{Sir Henry Royce}” Knock-Testing Apparatus CARBURETOR The carburetor is a special one which was designed by C. S. Kegerreis, with the cooperation of U. S. Bureau of Standards and of the members of the sub-committee in general. It was modeled after one which was built in the laboratory of the Anglo-American Oil Company in England by E.{Mr Elliott - Chief Engineer} M.{Mr Moon / Mr Moore} Dodds and F.{Mr Friese} H.{Arthur M. Hanbury - Head Complaints} Garner, and information about which was first given H.{Arthur M. Hanbury - Head Complaints} C. Dickinson by Mr. Garner on the occasion of a visit which Mr. Dickinson made to England during the summer of 1930. In this carburetor the fuel jet is fixed in size, the metering of the fuel being accomplished by means of a stream of secondary air passing over the jet, and variations in mixture-ratio being obtained not by adjusting the size of the fuel jet, but by varying the supply of secondary air. In order to facilitate the comparison of fuels, the carburetor has either two or four float bowls, as desired. It is also provided with a muffler for silencing intake noise, as well as with small reservoirs for holding the reference fuels and the fuel under test. POWER-ABSORBING MEDIUM The slotted-rotor type induction motor, which is connected with the engine by means of V-type belts, was selected because it performs three functions. The first is to start the engine, the second is to absorb the output of the engine, and the third is to automatically to hold the engine speed constant at 600 r.{Sir Henry Royce} p. m.{Mr Moon / Mr Moore} This latter is a thing which is of particular value on account of the importance of constancy of speed in knock testing, and of the desirability of relieving the operator of the burden of ensuring it. COOLING SYSTEM The engine is cooled by the boiling of water in a large jacket surrounding the cylinder. The heat is removed not in a conventional radiator, but by condensing the steam produced by the boiling of the water and returning the liquid thus formed to the system. By this means a uniform jacket temperature | ||