Development of a test bench for dynamic tests of part of the cooling assembly in commercial vehicles

摘要

Due to the growing need of reducing development time of new products and also to evaluate their reliability, a growing trend towards reduction of field tests has been noted. Bench tests, in contrast, are being more widely used because of the reduced time to carry them out, at much lower costs. In the automotive industry this trend has led to great efforts to make these bench tests as truthful as possible in order to increase their reliability. The quantity of simulated parameters is growing and this, or course, requires the collection of an ever increasing quantity of data from signal measurements (acceleration, temperature, pressure, flow, etc.) in experimental vehicles. The present work intends to show a test bench for durability tests of part of the cooling assembly for commercial vehicles which simulates the critical conditions of the operational torque output (mountain climbing and/or earth roads), with temperature, pressure, flow and vibration control (vertical-cross and vertical-longitudinal acceleration). Criteria have been established to accelerate the test, with extreme conditions maintained for longer periods than on actual field applications, reducing the time of low temperature, pressure, flow and acceleration incidence, thus enhancing the test time. The cooling system has gained special attention in modern engines and its components should be the object of close, detailed analysis. Previously, engines ran at lower temperatures and pressures in the system, but with the introduction of electronic engines, temperature levels usually rise to high values, around 110°C and average pressure of 1,2 bar. It is easy to conclude, therefore, that one small failure in the system can cause the loss of cooling liquid which would result in engine performance reduction, with the consequent stop of the vehicle which, of course, represents considerable costs.