Patent Application
20190353088
The present disclosure relates to internal combustion engines with variable compression ratios. More specifically, the present disclosure relates to a pre-chamber for varying compression ratios of internal combustion engines.
In certain internal combustion engines, the compression ratio is varied to optimize the performance of the engine. For example, a high compression ratio is utilized for lighter loads in which knock is not a primary concern. Whereas for high-load, knock limited conditions a lower compression ratio is utilized.
Typically, to vary the compression ratio the piston height was varied, which effectively changes the combustion chamber volume at top-dead-center. Such strategies, however, tend to compromise the flame propagation in the combustion chamber after the fuel-air mixture is ignited.
Thus, while current approaches achieve their intended purpose, there is a need for a new and improved system to vary the compression ratio of internal combustion engines.
According to several aspects, a pre-chamber for varying the compression ratio of an internal combustion engine includes a cylinder with an internal volume, a piston that moves within the cylinder to vary the volume of the internal volume of the cylinder, a spark plug, and a nozzle. The pre-chamber nozzle is in fluid communication with a primary cylinder of the internal combustion engine.
In an additional aspect of the present disclosure, the pre-chamber further includes a fuel injector that injects fuel into the pre-chamber cylinder, the spark plug igniting a fuel-air mixture in the cylinder.
In another aspect of the present disclosure, the primary cylinder further includes a second fuel injector that injects fuel into the primary cylinder.
In another aspect of the present disclosure, an intake port includes a second fuel injector that injects fuel into the intake port in fluid communication with the primary cylinder.
In another aspect of the present disclosure, the piston is positioned within the cylinder to reduce the volume in the cylinder for high compression ratio operation.
In another aspect of the present disclosure, the piston is positioned within the cylinder to expand the volume in the cylinder for low compression ratio operation.
In another aspect of the present disclosure, the volume in the cylinder is continuously variable.
In another aspect of the present disclosure, the volume in the cylinder is step variable.
In another aspect of the present disclosure, the nozzle is made of the same material as the pre-chamber cylinder.
In another aspect of the present disclosure, the nozzle is an insert made of a different material than the pre-chamber cylinder, the insert being made of a low heat-loss material.
According to several aspects, a pre-chamber for varying the compression ratio of an internal combustion engine includes a cylinder with an internal volume, a piston that moves within the cylinder to vary the volume of the internal volume of the cylinder, a spark plug, a fuel injector that injects fuel into the cylinder, the spark plug igniting a fuel-air mixture in the cylinder, and a nozzle. The pre-chamber nozzle is in fluid communication with a primary cylinder of the internal combustion engine.
In another aspect of the present disclosure, the primary cylinder further includes a second fuel injector that injects fuel into the primary cylinder.
In another aspect of the present disclosure, an intake port includes a second fuel injector that injects fuel into the intake port in fluid communication with the primary cylinder.
In another aspect of the present disclosure, the piston is positioned within the cylinder to reduce the volume in the cylinder for high compression ratio operation.
In another aspect of the present disclosure, the piston is positioned within the cylinder to expand the volume in the cylinder for low compression ratio operation.
In another aspect of the present disclosure, the volume in the cylinder is continuously variable.
In another aspect of the present disclosure, the volume in the cylinder is step variable.
According to several aspects, a pre-chamber for varying the compression ratio of an internal combustion engine includes a cylinder with an internal volume, a piston that moves within the cylinder to vary the volume of the internal volume of the cylinder, a fuel injector that injects fuel into a primary cylinder of the internal combustion engine and/or to an intake port in fluid communication with the primary cylinder, a spark plug and a nozzle. The pre-chamber nozzle is in fluid communication with a primary cylinder of the internal combustion engine. The spark plug ignites the mixture in the pre-chamber, with the jet of hot combustion gasses passing through the nozzle igniting the remaining fuel-air mixture in the primary cylinder.
In an additional aspect of the present disclosure, the piston is positioned within the cylinder to reduce the volume in the cylinder for high compression ratio operation.
In another aspect of the present disclosure, the piston is positioned within the cylinder to expand the volume in the cylinder for low compression ratio operation.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Referring to
Housed within the cylinder 30 is a piston 32 that reciprocates within the cylinder 30. An intake port 40 provides air into the main chamber 28 when an intake valve 44 opens as the piston 32 moves downward, and an exhaust port 42 allows combustion products to leave the main chamber 28 when an exhaust valve 46 opens and the piston 32 moves upward. In certain configurations, a second fuel injector 34 with a nozzle 36 provides direct injection of fuel into the main chamber 28. In other configurations, as shown as a pre-chamber 100 in
The sliding of the piston 13 allows the pre-chamber volume 17 to vary. For example, as shown in
The configurations described above, as well as those described below, provide improved combustion stability and dilution tolerance, enabling dilute or lean/stratified combustion strategies. Accordingly, the sliding piston 13 allows the volume of the pre-chamber 10 to be varied, which varies the compression ratio of the entire system including the cylinder 30. Depending on the actuator, the volume is continuously variable or variable in discrete steps. Note that changing the volume results in no change to the main chamber 28 geometry, which minimizes any detrimental effects on the flame propagation in the main chamber 28. The types of mechanisms utilized to actuate the piston 13 include, but are not limited to, cam-driven, screw-driven, direct acting solenoid-driven, rocker arm solenoid-driven, hydraulically actuated, and gear driven actuators.
The direct injection configuration shown in
In certain arrangements of either the direct injection configuration shown in
The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.
