ELECTRICAL INSTRUMENTS FOR AUTOMOTIVE RESEARCH 250024

Electrical instrumentation for research work has been developed to a high degree because of the great speed of action and the convenience of application of the electric current. The current serves to transmit instantly to a recording instrument the impulses imparted to it by a detecting device. There is available a great wealth of indicating, integrating and recording devices that can be used readily for automotive research by the aid of auxiliary devices, some of which can be purchased and some of which can be easily made in any ordinary model shop or toolroom. In the study of automotive mechanism the research engineers have drawn upon the investigation work of men in other lines of industry and have found it necessary to go back of these men to the scientific investigators who are attacking the elements of various problems in the physical and chemical laboratories.

The authors of the paper describe a number of instruments recently developed for measuring and recording engine-cylinder pressures, detecting and recording crankshaft and camshaft vibrations, detecting the sources of the noise, and measuring the intensity of noise vibrations.

The problem in devising such apparatus is to find an electrical device that will supply current, voltage or frequency that is proportional to and caused by the quantity it is desired to measure and then to select some instrument to go with it, using a standard article whenever possible. This paper has great value because it describes the elements that have been found best suited for the desired purposes and shows how the detecting, measuring and recording elements are combined into complete, practical working instruments. The authors also tell how the instruments are calibrated and used and explain the characteristics of diagrams made with them.

Research is a matter of measurement and analysis. In the usual investigation the two operations proceed concurrently, a new measurement requiring revision of the previous analysis and the revised analysis pointing to the need of new measurements. Improved instrumentation usually leads to new results, by permitting either more accurate measurements or measurements under new conditions. It is commonly found that after a problem has been solved the successful investigator has so arranged his study that he has been able to make a new and proper evaluation of the controlling factors. To do this, new instruments have been used or new methods of using old ones have been put into effect.

Because of the speed of action and the convenience of application of the electric current, electrical instrumentation has been developed to a high degree. A great wealth of indicating, integrating and recording devices is available. These instruments can be used readily for automotive research by the aid of auxiliary devices, some of which can be purchased and some of which can be made easily in any ordinary model shop or toolroom.

The electric current, when used with electrical instruments, serves to transmit to an indicating or recording device of proper characteristics the impulses that are supplied to it by a detecting device. The problem is to find an electrical device that will supply current, voltage or frequency proportional to and caused by the quantity it is desired to measure, and then to select some instrument to go with it, using a standard device whenever possible. A familiar example is the ordinary thermocouple installation for reading temperatures. Heat supplied to the couple generates a voltage that can be read by a potentiometer or a galvanometer conveniently placed. The voltage has a definite relation to the temperature at the couple. When using it, we have only to make sure that the temperature of the thermocouple is the same as the temperature of the body to be measured and to be sure of the calibration under the conditions of the installation.