Redundant, Thin-Wing, High-Pressure, Direct-Drive Valve Actuation System

A new variable mode valve actuation system for a heavy-duty engine was proposed and designed in this paper. The variable mode valve actuation system can significantly enhance braking safety and improve fuel economy and emission of heavy-duty engines through flexible switching among four-stroke driving mode, two-stroke compression-release braking mode, and cylinder deactivation mode on a conventional four-stroke engine. The switching was controlled by four-stroke driving modules and two-stroke braking modules, both of which have two operation states: effective state and failure state. For the control of the multi-cylinder engine, all cylinders can be divided into several groups, and all the four-stroke driving modules in the same group were controlled by one solenoid valve, as well as all the two-stroke braking modules were controlled by another solenoid valve. A hydraulic-mechanical multi-body dynamics model was established to investigate the switching response of the variable mode valve actuation system. The results indicated that when the engine operated at 2000 r/min, the switching of the four-stroke driving module and the two-stroke braking module required 30 °CA and 101 °CA at most, respectively. In addition, to avoid the conflict between the four-stroke driving valve lift and the two-stroke braking valve lift, the switching between the four-stroke driving mode and the two-stroke compression-release braking mode must have a reasonable sequence. The variable mode valve actuation system has an excellent switching response and it is convenient for the control of the multi-cylinder engine. Therefore, the variable mode valve actuation system has a good application prospect for heavy-duty engines.

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Analysis and optimization of a variable mode valve actuation system

International Journal of Engine Research ◽

10.1177/1468087420905994 ◽

2020 ◽

pp. 146808742090599

Author(s):

Yang Wang ◽

Jingchen Cui ◽

Xiangyu Meng ◽

Jiangping Tian ◽

Hua Tian ◽

...

Keyword(s):

Thermal Management ◽

Flow Rate ◽

Outlet Temperature ◽

Brake Specific Fuel Consumption ◽

Cylinder Pressure ◽

Heavy Duty ◽

Cylinder Deactivation ◽

Actuation System ◽

Variable Mode ◽

Valve Actuation

Braking safety of heavy-duty engines has always been the focus of the research, and the fuel economy and after-treatment thermal management during low-load operation of heavy-duty engines have also received much attention in recent years. A variable mode valve actuation system which can realize switching between four-stroke driving, two-stroke compression release braking and cylinder deactivation modes on a traditional four-stroke engine was proposed in this article. Two-stroke compression release braking mode of the variable mode valve actuation system can greatly enhance the braking safety, while the overload of valve train was a great challenge, especially during the release event. The effects of different release opening timing on cylinder pressure and the braking performance were studied. The results indicated that a higher cylinder pressure does not always lead to higher braking power. When the release opening timing was advanced by 6 °CA, the braking power reduced by only 9 kW (2.65%) at 1900 r/min compared with the initial value, while the maximum cylinder pressure reduced by 11.4 bar (20.8%). Besides, the variable mode valve actuation system can realize alternate three-cylinder cylinder deactivation mode on a six-cylinder turbocharged engine, which can improve the brake-specific fuel consumption by 14.67% and increase the turbine outlet temperature by 63.6 °C and reduce the exhaust flow rate by 50.66% at lightly load idle. Meanwhile, when the engine load is less than 50% at the rated speed, the three-cylinder cylinder deactivation mode can improve the brake-specific fuel consumption, increase the turbine outlet temperature and reduce the exhaust flow rate. The increase of the turbine outlet temperature and the decrease of the exhaust flow rate are very beneficial to improve the efficiency of the after-treatment thermal management of heavy-duty engines.

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