The Jacobs Engine Brake - A New Concept in Vehicle Retarders

Cummins, C. Lyle; Haviland, G. S.

doi:10.4271/610294

Cited by 3 publications

(2 citation statements)

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“…Compression-release brake 23,24 works through the control of the engine valves, and at least one exhaust valve per cylinder is opened to release the compressed gas to exhaust manifold when the piston is close to the top dead center (TDC) of compression stroke, which can prevent the energy stored in the compressed gas from being returned to the piston on the subsequent expansion stroke; thus, the engine is converted from a power-producing machine into a power-consuming air compressor. 11,25 The braking performance of the compression-release brake is the best of all the practical products that generate one braking event per four-stroke cycle or two crank revolutions. 10 To obtain greater brake power, the two-stroke compression-release brake has become the focus of the research, which generates one braking event per crank revolution.…”

Section: Introductionmentioning

confidence: 99%

Development of a variable mode valve actuation system for a heavy-duty engine

Wang

Long

Cui

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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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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Section: Introductionmentioning

confidence: 99%

Development of a variable mode valve actuation system for a heavy-duty engine

Wang

Long

Cui

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part D:

View full text Add to dashboard Cite

show abstract

“…Compression release brake works through the control of the engine valve, at least one exhaust valve per cylinder is opened to release the compressed gas to exhaust manifold when the piston close to top dead center (TDC) of compression stroke, 25,28 which can prevent the energy stored in the compressed gas from being returned to the piston on the subsequent expansion stroke; thus, the engine is converted from a power-producing machine into a power-consuming air compressor. 29,30 It can be divided into four-stroke compression release brake and two-stroke compression release brake. Four-stroke compression release brake generates one braking event per four-stroke cycle or two crank revolutions.…”

Section: Introductionmentioning

confidence: 99%

Research on two-stroke compression release braking performance of a variable mode valve actuation system

Wang

Long

Cui

et al. 2019

International Journal of Engine Research

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In order to enhance the braking safety and improve the fuel economy and emission of heavy-duty engines, a variable mode valve actuation system which can switch operation modes flexibly among four-stroke driving, two-stroke compression release braking, and cylinder deactivation modes on a four-stroke engine was developed in this article. The switching was controlled by the four-stroke driving module and the two-stroke braking module, both of which have two states: effective state and failure state. Besides, a full-cycle numerical model of a six-cylinder turbocharged engine was established for the performance analysis of two-stroke compression release braking mode. The orthogonal design method was introduced in the present study to obtain the optimum valve parameters which can result in high braking power and maintain the maximum cylinder pressure at a lower level at the same time. Then, the two-stroke compression release brake braking power with the optimum valve parameters was compared with four-stroke compression release braking power. Meanwhile, the two-stroke braking cam profile of the variable mode valve actuation system was designed according to the optimum valve parameters, and the two-stroke braking performance with the dynamic valve lift of the variable mode valve actuation system was validated by the numerical model including the hydraulic system. The results indicated that a higher engine speed leads to higher braking power at the same valve lift. Besides, two-stroke compression release brake braking power of the variable mode valve actuation system achieved 525.3 kW at 2600 r/min and 358.1 kW at 1900 r/min, 52.9% and 71.3% higher than four-stroke compression release braking power, respectively. Although the two-stroke compression release brake braking power with dynamic valve lift is slightly less than that with the optimum valve parameters, it is still much higher than that of the four-stroke compression release braking power. Therefore, it has a good application prospect for heavy-duty engines.

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