METHOD AND APPARATUS FOR PRODUCTION HOT TESTING OF ENGINES UNDER LOAD

This application discloses a method and apparatus for hot testing on a production basis, automobile engines as they come off the assembly line, for the purpose of performing a final check on such engines before they are installed in the automobile. While previously, automotive engines have been subject to many checks of their individual systems before reaching a condition where they are to be installed in an automobile, for example, by checking of the carburation system and the ignition timing, there has been no final check of the engine, to make sure the three main systems of the automobile engine (i.e., carburetion, ignition and combustion) are all working properly together before installing the engine in the automobile. After much work it was found that such a test could be performed on the engine by running it under load and examining certain exhaust gas emissions. It has been found that carbon monoxide (CO) and hydrocarbons (HC) are the most perceptive indicators of engine malfunctions. Accordingly, the green engines coming off the assembly line are tested at three key points or KEY MODES of operation at which emission related engine malfunctions are most likely to appear, if they exist. These points of operation are high cruise, low cruise, and idle. The engine, after it comes off the assembly line is placed in a production test stand wherein the connections for water, oil and exhaust are made, the engine is started, accelerated to the high cruise speed, and allowed to warm up for a predetermined time, after which time, measurements of HC and CO are taken and an appropriate indicator light lit to indicate that the engine either is within limits of HC and CO at this speed, or does not pass for some reason. The same procedure is followed in the low cruise and idle speeds. If the engine passes all three modes of operation, it is removed from the test stand and passed for installation in the motor vehicle. If one or more of the indicator lights show a reject condition, the engine is automatically removed from the production test stand and routed to a repair loop for further testing. The CO and HC evaluations at the production test stand may be recorded on a manual or automatic system to arrive coincident with the engine at the repair stand. In the repair loop, adjustment or repair to correct malfunctions is facilitated by the use of a truth chart having a reject pattern matching that shown by the recording system. Both in the production test stand and in