ISO 20574:2019 pdf download.Road vehicles – Durability test method for starter motor for stop and
start system.
Stop and start systems contribute to fuel saving by stopping the engine when its operation is not needed, and to start the engine automatically when its operation is needed. ‘l’he more frequent starting of the engine requires higher durability of the starter motor. Since there is no standard to evaluate the durability of starter motors for stop and start systems, individual specifications are used by engine and/or vehicle manufacturers and starter motor manufacturers. Because the stop and start systems require much more frequent starter motor operations, the testing period is much longer compared to conventional starter motors.
In addition to engine and/or vehicle manufacturers and starter motor manufacturers, testing companies also began to conduct tests. In order to carry out the time-consuming test accurately and to use the test results effectively, the test procedure in this document includes how to summarize the test results.
ISO 20574 defines requirements and recommendations for starter motor durability testing of 12 V start systems for internal combustion engines. This includes test methods, test procedures and capabilities of test benches.
ISO 20574 items should be specifically considered:
1) In case of engine simulator, multiple starter motors can be tested simultaneously with the same ring gear. In that case, the orientation of the starter motors deviate from those of the target application. Hence, the usage of multiple starter motors shall correspond to the test purpose (e.g. verification of brush durability but not verification of pinion and ring gear durability).
2) The starter motor manufacturer and engine and/or vehicle manufacturers should agree starter motor temperature level during the durability test. Different approaches to define temperature level are established.
For example:
— test at maximum brush temperature defined by starter motor manufacturer;
— test at maximum brush temperature derived from vehicle real drive cycle; and
— test at an average brush temperature derived from brush temperature distributions of vehicle real drive cycle.
Each approach covers different testing purposes such as focusing on thermal stress, test duration, mechanical loads or balanced field representation.
3) The starter motor manufacturer and engine and/or vehicle manufacturers should define the test pass criteria and define test stop criteria according to TabIe.ISO 20574-2019