1. Field of the Invention
The present invention relates generally to the field of tools for tuning a diesel engine by adjusting the elevation of the follower on each mechanical injector unit, and more specifically to a tuning tool including a cylindrical housing having a perpendicularly protruding arm member for placing against the top of a follower, and including a spring-biased plunger protruding through one end of the housing for bearing against the injector fuel supply flange, and including a light source at the other end of the housing, and containing an electric power source and a circuit for delivering electricity from the power source to the light source, the circuit including a first conductor member attached to the plunger and a second conductor member attached to the housing which become aligned to complete the circuit only when the housing is moved relative to the plunger to a specific, pre-calibrated position, so that when the plunger is placed against the injector fuel supply flange and the housing is moved longitudinally against the biasing of the plunger until the housing arm member makes contact with the top of the follower, the light source is activated only when the follower elevation reaches proper adjustment.
2. Description of the Prior Art
There have long been tools for measuring the elevation of a diesel fuel injector follower relative to the injector body to determine if the injector is properly adjusted. Proper tuning is important because mis-adjustment leads to poor fuel efficiency and a heavy discharge of unburned gaseous pollutants. The Federal Government and the State of California now require that diesel engines be certified as correctly tuned, and truck drivers can receive traffic tickets if their trucks produce too much smoke.
The best known tool of this type is a shaft having one end narrowed to a needle tip and having a radially protruding arm portion. The shaft is positioned parallel to the longitudinal axis of the follower and the shaft needle tip is inserted into a small tool receiving hole in the injector fuel supply flange. The elevation of the follower is then adjusted until the tool arm portion just touches the top of the follower. This type of tool is calibrated during manufacture to one permanent tuning measurement. Therefore, a disadvantage of this tool is that a shop which services different types of diesel engines must purchase a separate tool for each engine type. Another problem is that, under normal shop lighting conditions, it can be difficult to see whether the proper contact between the tool and the top of the follower has been made. Thus the tuning work can become frustrating and time-consuming.
Another prior tuning tool is a cylinder having an adjustable calibration dial and gauge at one end, and a follower and rocker arm receiving hollow in the other end. The dial is rotated to calibrate the tool for a specific adjustment specification. An adjustable contact rod extends from the dial end parallel to the cylinder to touch the injector fuel supply flange. The hollow is placed over the follower and the follower is adjusted until the contact rod just touches the fuel supply flange. A problem with this tool is that the elongate rod can be accidentally bent or the calibration dial accidentally rotated, leading to mis-measurement and mistuning. Another problem is that this tool is expensive to manufacture and subject to failure with prolonged, rugged shop use.
It is thus an object of the present invention to provide a diesel tuning tool which clearly indicates proper adjustment by activation of a light source.
It is another object of the present invention to provide such a tool which is durable and not easily thrown out of calibration with rough handling.
It is still another object of the present invention to provide such a tool which can be calibrated to numerous settings so that a single tool can be used to tune virtually all types of diesel engines.
It is finally an object of the present invention to provide such a tool which is simple and inexpensive to manufacture.