US 5,680,841 A · Internal combustion engines with combined cam and electro-hydraulic engine valve control

Abstract

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).

Claims38

Dependent claims

An internal combustion engine comprising:

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
a hydraulic fluid control for selectively controlling hydraulic fluid pressure in said hydraulic linkage to selectively modify the openings of said engine cylinder valve in response to said lobe, said hydraulic fluid control being selectively operable to allow said engine cylinder valve to remain completely closed in response to a first one of said lobes and to open in response to a second one of said lobes, each of said plurality of lobes being selectable at various times to be either said first one or said second one of said lobes.

2 more elements

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, said method comprising the steps of:

detecting whether said engine is in a positive power mode of operation or a compression release engine braking mode of operation;
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;
and
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 but not in response to said exhaust lobe.

1 more element

Dependencies are inferred from the claim text.

Internal combustion engines with combined cam and electro-hydraulic engine valve control

Life of this patent

Internal combustion engines with combined cam and electro-hydraulic engine valve control

Life of this patent

Abstract

Claims38