Research And Settlement Of GALANT Vehicle Alternator Regulator Failure

As modern cars increasingly become small, light-weight, secure and environment-friendly, and national security and emission statutes are increasingly stringent, different complete vehicle and engine manufacturers constantly improve product service performance, increase product safety and reliability, and maximize satisfaction of customers'expectation so as to adapt to the international trend. The 4G69 MIVEC engine introduced by our company in 2005 is a typical example. Much improvement has been made in it as compared with previous 4G6 engines; for instance, the output power and torque have been upgraded and emission has reached the European IV Standard. In the improvement measures, the alternator and power steering pump are exchanged in positions, and the alternator is deployed in front of the engine bay, neighboring the exhaust manifold, in order to correspond to collision performance. Implementation of this measure greatly increases the safety performance of vehicles, but brings thermal hazard to alternators - the impact of high temperature in the exhaust manifold leads to burnout of alternator IC regulators of Southeast GALANT vehicles with this type of engine in many tests, and hence, failure of the alternators to generate electricity.Failure of alternator IC regulators of GALANT vehicles occurred for many time in Beijing Road Test Plant, but there have been 9,000 alternators of the same model installed in Beijing Jeep OUTLANDER models, without this failure. Therefore, SAME believes that the reason for the failure is probably not a single issue of the product quality. To find the actual reason for the failure of alternator IC regulators, our company conducted meticulous fault investigation and reason analysis, and complete vehicle thermal hazard tests for many times jointly with the alternator manufacturer Jinzhou Halla Electrical Equipment Co., Ltd., Southeast Motor, and Japan's Mitsubishi Motors. Finally, we resolved the problem and won recognition and trust from our customers. The research work in this text gives the following conclusion:1. The actual reason for failure of alternator IC regulators: ①We have confirmed that the failure modes of all alternator IC regulators are MOSFET soldering tin melting after detailed analysis of the alternator fault pieces;②We implemented a high-temperature durability test at 150oC to JHECO and KD alternators and an IC regulator individually, and specified a performance decline in the JHECO alternator after 48 hours, but it was in normal work. The KD alternator IC regulator was burnt down due to high temperature after 16 hours and unable to generate electricity. The JHECO alternator was superior to the KD parts in resistance to high temperature and had no problem;③We have carried out overcurrent and overvoltage tests to IC regulators; the failure modes are MOSFET welding lead burnout, different from the one of GALANT vehicles. That is, failure of IC regulators of GALANT vehicles was not caused from overcurrent or overvoltage;④MMC conducted thermal hazard tests to GALANT vehicles; the test results are: the vehicle cooling systems were normal, but the alternator S terminals had temperature of 151oC, exceeding the allowable value by 1oC. MMC proposed adoption of an additional heat protector to reduce 5oC;⑤We carried out investigation into the tests of GALANT vehicles by Beijing Road Test Plant, where the maximum suction temperature on the back of the alternator was 231oC in the complete vehicle tests, and the measured chip temperature of the alternator regulator was displayed as 204.6oC. According to the analysis, the inflow of thermal temperature from the alternator exterior (exhaust pipe) to the alternator side, which eventually led to the temperature rise in the regulator side, was the fundamental cause for burnout of IC regulators;⑥Conclusion: The thermal hazard of vehicles was the main reason for burnout of alternator IC regulators;Burnout of GALANT vehicle alternator regulators was hazard due to high-temperature air flow to the alternators, and thereby, in order to avoid the hazard, we judge it is necessary to lower the suction temperature on the back of alternators. Besides, the programme of additional heat protector on alternators is used according to MMC recommendations.2. Solution 1 to the thermal hazard problem - alternator improvement:①With additional heat protector on the back of alternators, exhaust manifold heat sources can be prevented from convection and radiation to the alternators, and the temperature behind a alternator (the resin part) dropped from 182oC in case of having no heat protector to 128oC. Moreover, the temperature of the alternator S terminal fell from 153oC before use of the solution to 133oC, down by 20oC, and thus, satisfying the standard requirements of not exceeding 150oC at most.②Alternator IC regulators were enhanced in their heat-resisting capacity; the MOSFET surface area increased, with the chip size changing from 3.06X2.21 to 3.52X3.41. The radiating effect was upgraded by 70%, and the bearing capacity for rapid energy changes was augmented by 127%;③The pressure-resisting level of alternator IC regulators was improved from 100V to 150V, and the ability to resist sudden pulse voltage was increased;④MOSFET S terminal leads increased from one to two, which enhanced the overcurrent-resisting capacity and alternator IC regulator reliability.3. Solution 2 to the thermal hazard problem - exhaust manifold heat protector improvement: By referring to the catalytic heat insulation structure, a 3M cushion with 6.5mm thick was inserted between two sheets of the exhaust manifold heat protector, able to effectively lower the temperature outside the heat protector of a alternator from 160oC to 135oC, down by 25oC. Therefore, the thermal hazard problem was eliminated at the source, and convection and thermal radiation to alternators were greatly decreased.4. In order to verify the effect of the solutions to the alternators, the following endurance test was conducted to individual alternators:①Destructive high-temperature endurance comparison test: Under the same high-temperature operation test condition at 150oC, alternators after use of the solutions worked normally for 300 hours, while those before use of the solutions could only maintain normal operation for 182 hours. In comparison, MELCO alternators were burnt out after 50 hours due to overheating. It can be seen that the alternators after use of the solutions were greatly enhanced in their high temperature-resisting capacity indeed.②It was OK in a high-temperature endurance test/50~100oC max/3,000rpm/1,000Hr (based on the Alternator ES-M150190 Technical Standard);③It was OK in a high-speed endurance test/12,000rpm/500Hr;④It was OK in a high-speed endurance test/0-10,000rpm/250Hr (3,600 cycles);⑤It was OK in vibration (resonance) tests/33G/342Hz/X and Y, 16 hours for each.The above test results were OK, proving that the solutions to alternators are effective.5. To validate the reliability of alternators, SAME conducted a bench endurance test of alternators for 450 hours. After the test, alternators looked good without abnormal running sounds, and the heat protector had no fracture. They carried out cold and hot performance detection on the alternators, and the performance was OK, and thus, confirming the solutions to the alternators were effective.6. In order to check the actual improvement effect of alternators after use of the solutions, these alternators were installed in Southeast GALANT test vehicles, and underwent 600 cycles (about 40,000KM) of running tests. After the tests, the alternators were in normal work without any defect, and looked good without abnormal running sounds, and the heat protector had no fracture. After that, they carried out cold and hot performance detection on the alternators, and the performance was OK, and finally confirming the solutions to the alternators were effective. During over 1 year of implementation, the above solutions have been proved in the market, and no burnout has occurred in alternator IC regulators of GALANT vehicles.The research of this text aims to reveal the impact and hazard on the service life of automotive parts like a alternator, and to seek settlement countermeasures and prevention measures, with practical guidance significance. Later, SAME conducted corresponding thermal hazard tests to BYD F6 and Jianghuai complete vehicles with 4G69 MEVIC engines. Similar failure was prevented from happening again, and thus, winning the support and trust from customers.