Experimental Valve Motion Measurement Study for Mid-Range Diesel Engine
2022-01-0758
03/29/2022
- Event
- Content
- Compression brake mechanism is one of the crucial technologies in diesel engines which not only reduces engine speed during downhill over speeding condition by controlled opening of the exhaust valve before the power stroke but is also helpful to reduce brake pad wear by assisting in vehicle braking. Clearance between valve and piston during compression brake event is critical design factor for successful design. Multiple events of valve to piston hitting were observed while testing in field as well as in test cells and these failures were highest in compression brake engines. Based on Fault Tree Analysis (FTA) certain design changes were implemented in engine components and to validate the design changes, a test was performed to understand valve motion dynamics during engine running condition. This valve motion measurement study has been performed for the first time for mid-range diesel engines in CTCI. The displacement sensors were used for valve lift measurement. Special instrumentation was done on valve cover to integrate sensor setup. Also, modification was done in exhaust valve spring retainers to incorporate displacement sensors for data acquisition. Steady state measurement data was taken for 50 cycles at various engine operating conditions such as motoring and firing. Peak cylinder Pressure (PCP) sensor was installed in one cylinder and valve displacement data was acquired in angle domain. Piston Profile was measured offline with 5-degree resolution in static condition. Upon test completion, acquired valve displacement data was compared graphically with piston profile to evaluate valve to piston clearances for final validation. Also, no contact was observed between valve and piston for compression brake event for all RPMs acquired for firing and motoring conditions. Initial results revealed that we have design margin greater than 3 times than minimum clearance requirement. After teardown of engine, no stamping on piston observed on any cylinder and thereby validates the valve motion study.
- Citation
- Mestry, K., Gundecha, D., Mahajan, P., Saha, S. et al., "Experimental Valve Motion Measurement Study for Mid-Range Diesel Engine," SAE Technical Paper 2022-01-0758, 2022, .