Method and system of improving engine braking by variable valve actuation
AssigneeDiesel Engine Retarders, Inc.
InventorsZhou Yang, James F. Egan, III
Life of this patent
Estimating the term…
Abstract
The present invention relates to methods of improving engine braking of a reciprocating piston internal combustion engine by variable valve actuation. One embodiment of the present invention enables independent two-valve actuation for each cylinder, and engine braking horsepower can be optimized using two-valve braking at high engine speeds and one-valve braking at low speeds. Another embodiment of the present invention enables better a sequential valve actuation to reduce engine braking load and compliance. Another embodiment of the present invention enables better engine starting and warming up by controlling timing and lift of each valve.
Claims29
A method of optimizing engine braking power during an engine braking event for multiple engine speeds in a multi-valve internal combustion engine having a piston which reciprocates in a cylinder, said method comprising the steps of:
- selecting an engine speed as a cross-over point between one-valve engine braking and multi-valve engine braking in the cylinder;
- measuring at least one engine parameter to determine the current engine speed;
- determining whether the current engine speed is above, equal to, or below the cross-over point engine speed;
- and
- modifying the operation of at least one engine valve in the cylinder during the engine braking event responsive to the determination of whether the current engine speed is above, equal to, or below the cross-over point engine speed.
A valve actuation system for actuating at least one engine valve to produce an engine braking event in a multi-valve internal combustion engine, the valve actuation system comprising:
- a housing, having a fluid linkage formed therein;
- means for selectively displacing hydraulic fluid located in the fluid linkage;
- means for controlling the displacement of the hydraulic fluid in the fluid linkage to modify the operation of the at least one engine valve responsive to a determination of the current engine speed;
- and
- means for actuating the at least one engine valve to produce the engine valve event, said actuation means slidably received in said housing and operatively connected to said displacement means through the fluid linkage,
- wherein said displacement control means selectively modifies the operation of the at least one engine valve between one-valve operation and multi-valve operation during the engine braking event.
A valve actuation system for selectively switching between one-valve actuation and multi-valve actuation to produce an engine valve event in a multi-valve internal combustion engine, the valve actuation system comprising:
- a housing having first, second, and third internal bores and a fluid linkage formed therein;
- a hydraulic fluid supply in communication with the fluid linkage;
- a master piston assembly slidably disposed in the first bore;
- a cam for imparting motion to said master piston assembly;
- a first slave piston assembly slidably disposed in the second bore for actuating a first engine valve;
- and
- a second slave piston assembly slidably disposed in the third bore for actuating a second engine valve, said second slave piston assembly in selective communication with said master piston assembly.
A valve actuation system for selectively switching between one-valve actuation and multi-valve actuation to produce an engine valve event in a multi-valve internal combustion engine, the valve actuation system comprising:
- a housing having first, second, and third internal bores and a fluid linkage formed therein;
- a hydraulic fluid supply in communication with the fluid linkage;
- a master piston assembly slidably disposed in the first bore;
- a cam for imparting motion to said master piston assembly;
- a first slave piston assembly slidably disposed in the second bore for actuating a first engine valve;
- a second slave piston assembly slidably disposed in the third bore for actuating a second engine valve;
- a hydraulic passage connecting said first slave piston assembly to said second slave piston assembly;
- and
- valve means disposed in said hydraulic passage for selectively supplying hydraulic fluid to said second slave piston assembly and permitting actuation of the first and second engine valves.
Dependencies are inferred from the claim text.