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US 5,839,453 AGranted
Internal combustion engines with combined cam and electro-hydraulic engine valve control
AssigneeDiesel Engine Retarders, Inc.
InventorHaoran Hu
Life of this patent
Estimating the term…
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AssigneeDiesel Engine Retarders, Inc.
InventorHaoran Hu
Estimating the term…
An internal combustion engine has electrically controlled hydraulic linkages between engine cams and engine cylinder valves. If it is desired to skip a cam lobe or to modify the response of an engine cylinder valve to a cam lobe, hydraulic fluid is selectively released from the associated hydraulic linkage to permit lost motion between the cam and the engine cylinder valve. Electrically controlled hydraulic fluid valves are used to produce the selective release of hydraulic fluid from the hydraulic linkages. The mode of operation of the engine can be changed (e.g., from positive power mode to compression release engine braking mode or vice versa), or more subtle changes can be made to modify the timing and/or extent of engine cylinder valve openings to optimize engine performance for various engine or vehicle operating conditions (e.g., different engine or vehicle speeds).
An internal combustion engine having a four-cycle positive power mode and including an engine cylinder valve which is selectively openable and closable, a cam having a plurality of lobes synchronized with possible openings of said engine cylinder valve, a hydraulic linkage containing hydraulic fluid operatively coupled between said cam and said engine cylinder valve for selectively responding to said lobes by causing said valve to open, and an electrically operated valve controlled by an electronic control circuitry for selectively releasing hydraulic fluid from said hydraulic linkage in order to selectively modify the openings of said engine cylinder valve in response to said lobes, said electrically operated valve being selectively operable to allow said engine cylinder valve to remain completely closed in response to any first one of said lobes and to open in response to any second one of said lobes, characterized in that said electrically operated valve is openable and closable multiple times during each time period of operation of said engine comparable to each four cycles of positive power mode operation of said engine.
The method of operating an internal combustion engine which has a selectively openable engine cylinder valve, a cam having an exhaust lobe and a compression release lobe, and a hydraulic linkage containing hydraulic fluid operatively coupled between said cam and said engine cylinder valve for selectively responding to said exhaust and compression release lobes by selectively opening said engine cylinder valve, the method including the steps of detecting whether said engine is in a positive power mode of operation or a compression release engine braking mode of operation, and if said engine is in said positive power mode of operation, controlling hydraulic fluid pressure in said hydraulic linkage so that said hydraulic linkage opens said engine cylinder valve in response to said exhaust lobe but not in response to said compression release lobe, or if said engine is in said compression release mode of operation, controlling hydraulic fluid pressure in said hydraulic linkage so that said hydraulic linkage opens said engine cylinder valve in response to said compression release lobe, characterized in that in said compression release mode of operation, the hydraulic fluid pressure in said hydraulic linkage is controlled so that said engine cylinder valve does not open in response to said exhaust lobe.
A compression release braking system for an internal combustion engine including an engine cylinder exhaust valve which is selectively openable and closable, a cam having a lobe synchronized with a possible opening of said exhaust valve, a hydraulic linkage containing hydraulic fluid operatively coupled between said cam and said exhaust valve for selectively responding to said lobe by causing said valve to open, and a hydraulic fluid control having a plurality of different operating conditions in which the hydraulic fluid control has respective different effects on the hydraulic fluid pressure in said hydraulic linkage in response to said lobe, characterized in that said lobe is a compression release engine braking lobe synchronized with a possible compression release opening of said exhaust valve, and the hydraulic fluid control is responsive to a variable operating condition of said engine by changing said operating conditions of said hydraulic fluid control at different times during response of the hydraulic linkage to said lobe.
Dependencies are inferred from the claim text.