System for variable actuation of a valve of an internal-combustion engine

Patent metadata

Field	Value
Publication number	US-10240524-B2
Application number	US-201615353068-A
Country	US
Kind code	B2
Filing date	Nov 16, 2016
Priority date	Dec 24, 2015
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

Described herein is a system for variable actuation of an engine valve of an internal-combustion engine, where the system is able to actuate the engine valves, selectively, in a four-stroke operating mode and in a two-stroke operating mode, on the basis of the operating conditions of the engine.

First claim

What is claimed is:

1. A system for variable actuation of an engine valve of an internal-combustion engine, comprising:
a hydraulic apparatus including:
a master piston,
a slave piston configured to be driven by said master piston by a volume of fluid set between said master piston and said slave piston, and
a solenoid valve;
wherein said system further comprises:
a camshaft designed to drive said master piston in motion, which has a cam profile for governing, through said master piston, said engine valve in a four-stroke engine operating mode;
a control unit configured for controlling said solenoid valve so as to govern said engine valve, within said four-stroke engine operating mode, according to a lift and/or opening and closing times that are variable as a function of one or more parameters indicative of operating conditions of the engine;
wherein:
said camshaft or a further camshaft has a second cam profile for governing said valve in a two-stroke engine operating mode;
said hydraulic apparatus comprises:
a second master piston configured to be actuated by said second cam profile and that is designed to drive said slave piston by a second volume of fluid set between said second master piston and said slave piston;
a hydraulic circuit defining:
a first chamber mobile within which is said master piston;
a second chamber mobile within which is said second master piston; and
a third chamber mobile within which is said slave piston;

said solenoid valve is configured for:
controlling communication of said first and second chambers with said third chamber and with said outlet;
assuming a first state where said first and second chambers are both in communication with said outlet so as to render said slave piston independent from movement of said first and second master pistons;
assuming a second state where i) said first chamber is in communication with said outlet so as to render said slave piston independent from movement of said first master piston, and ii) said second chamber is in communication with said third chamber; and
assuming a third state where i) said first chamber is in communication with said third chamber, and ii) said second chamber is in communication with said outlet so as to render said slave piston independent from movement of said second master piston; and

said control unit is configured for controlling said solenoid valve so as to govern said engine valve selectively in one or the other of the two-stroke engine operating mode and the four-stroke engine operating mode.

2. The system according to claim 1 , wherein said control unit is configured for selecting the two-stroke or four stroke engine operating mode and is configured for governing said solenoid valve on the basis of the two-stroke or four stroke engine operating mode selected and on the basis of one or more parameters indicative of the operating conditions of the engine.

3. The system according to claim 1 , wherein in said first state said third chamber is in communication with said outlet.

4. The system according to claim 1 , wherein said outlet is connected to a fluid accumulator.

5. The system according to claim 1 , wherein said control unit is configured for selecting the two-stroke or four-stroke engine operating mode on the basis of engine load.

6. The system according to claim 5 , wherein said control unit is configured for comparing a reference value stored therein with a measured parameter indicative of the engine load.

7. A method for controlling a system for variable actuation of an engine valve of an internal-combustion engine, wherein said system comprises:
a hydraulic apparatus including:
a master piston actuated by a camshaft, said camshaft has a first cam profile for governing said engine valve in a four-stroke engine operating mode, and said camshaft or a further camshaft has a second cam profile for governing said engine valve in a two-stroke engine operating mode;
a slave piston configured to be driven by said master piston by a volume of fluid set between said master piston and said slave piston;
a second master piston configured to be actuated by said second cam profile and that is designed to drive said slave piston by a second volume of fluid set between said second master piston and said slave piston; and
a solenoid valve configured for assuming:
a first state where said volume of fluid is set in communication with an outlet so as to render said slave piston independent from movement of said master piston;
a second state where said second volume of fluid is set in communication with the outlet so as to render said slave piston independent from movement of said second master piston; and
a third state where both of said first and second volumes are set in communication with the outlet;

a control unit configured for controlling said solenoid valve so as to govern said engine valve according to a lift and/or opening and closing times that are variable as a function of one or more parameters indicative of operating conditions of the engine;
said method further comprising:
selecting one between the two-stroke engine operating mode and the four-stroke engine operating mode on the basis of the operating condition of engine load;
controlling said solenoid valve on the basis of the selected two-stroke or four-stroke engine operating mode so as to govern said engine valve in said selected two-stroke or four-stroke engine operating mode;
for at least one of the two-stroke and four-stroke engine operating modes, controlling said solenoid valve so as to govern said engine valve according to a lift and/or opening and closing times that are variable as a function of one or more parameters indicative of the operating conditions of the engine; and
on the basis of the selected two-stroke or four-stroke operating mode, varying the state of said solenoid valve between said third state, said second state and said first state.

Assignees

• Fiat Ricerche

Inventors

• Lucatello Marco
• Vattaneo Francesco
• Doria Vittorio

Classifications

• F02D15/02

  by alteration or displacement of piston stroke · CPC title

• F02B75/02

  Engines characterised by their cycles, e.g. six-stroke · CPC title

• F01L1/245

  Hydraulic tappets · CPC title

• F01L11/02 Primary

  in piston · CPC title

• F02B69/06 Primary

  for different cycles, e.g. convertible from two-stroke to four stroke · CPC title