Abstract:

To address the issue of excessive driving system load caused by high valve opening pressure during two-stroke braking in heavy-duty diesel engines, this study proposes an integrated hydraulic variable mode valve system (HVMVS) capable of dynamic valve motion pattern switching. A six-cylinder diesel engine simulation model was established using GT-Power software to investigate optimal valve operation parameters that achieved high braking torque while maintaining low maximum cylinder pressure. Brake performance analysis was conducted across different rotational speeds for diesel engines equipped with HVMVS, including comparative evaluations with conventional variable valve systems. The results show that at rated engine speed, the HVMVS-equipped two-stroke braking system generates 1 158 Nm effective braking torque with a maximum cylinder pressure of 2.3 MPa, leading to a 62% reduction compared to alternative systems. The HVMVS demonstrates significant advantages in mitigating both maximum in-cylinder pressure and drive mechanism load during two-stroke braking operations, thereby enhancing operational reliability. These findings indicate promising application prospects for HVMVS in heavy-duty engine applications.

Key words: vehicle safety, exhaust braking technology, variable valve drive system, fully hydraulic variable valve system, two-stroke braking technology