System and method for variable actuation of a valve of an internal-combustion engine, with a device for dampening pressure oscillations

Patent metadata

Field	Value
Publication number	US-10156163-B2
Application number	US-201615280577-A
Country	US
Kind code	B2
Filing date	Sep 29, 2016
Priority date	Oct 13, 2015
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

A system for variable actuation of an engine valve of an internal-combustion engine includes a master piston and a slave piston, driven by the master piston. A control valve controls a communication of a volume of a pressurized fluid with a lower pressure environment, which is connected to a fluid accumulator, and an electronic control unit controls the electrically operated control valve. A device for dampening pressure oscillations is connected to the volume of pressurized fluid and includes an additional volume adapted for receiving fluid from the volume of pressurized fluid only when, following upon oscillations of the pressure in the volume of pressurized fluid, the pressure exceeds a maximum threshold value, which is higher than a mean pressure value that is set up in the volume of pressurized fluid when the master piston drives the slave piston in normal operating conditions.

First claim

What is claimed is:

1. A system for variable actuation of an engine valve of an internal-combustion engine, comprising:
a master piston driven directly or indirectly by a cam of a camshaft of the internal-combustion engine;
a slave piston, which drives said engine valve and is hydraulically driven by said master piston, by means of a volume of pressurized fluid interposed between the master piston and the slave piston;
an electrically operated control valve, which controls a communication of said volume of pressurized fluid with a lower pressure environment, said lower pressure environment being connected to a fluid accumulator; and
an electronic control unit for controlling said electrically operated control valve on the basis of one or more parameters indicating the operating conditions of the engine and/or of the system for variable actuation of the engine valve,
a device for dampening pressure oscillations in the volume of pressurized fluid connected to said volume of pressurized fluid, and
said oscillation dampening device comprising an additional volume adapted for receiving fluid from said volume of pressurized fluid only when said pressure exceeds a maximum threshold value.

2. The system according to claim 1 , further comprising an auxiliary chamber comprising said additional volume, said auxiliary chamber in communication with said volume of pressurized fluid and defined by a movement of a movable member against the action of a return spring, said spring having a load such that said movable member displaces against the action of the spring, thus creating said additional volume, only when the pressure in the volume of pressurized fluid exceeds the aforesaid maximum threshold value.

3. The system according to claim 2 , wherein the communication of the aforesaid auxiliary chamber with the volume of pressurized fluid is a permanently opened communication.

4. The system according to claim 3 , wherein said permanently opened communication includes a restricted passage.

5. The system according to claim 2 , wherein said auxiliary chamber and said movable member are provided within the body of the oscillation dampening member, said body comprising a separate element.

6. The system according to claim 2 , wherein said auxiliary chamber and said movable member are provided within the body of said slave piston.

7. The system according to claim 2 , wherein said auxiliary chamber and said movable member are provided within the body of said master piston.

8. The system according to claim 2 , wherein said auxiliary chamber and said movable member are provided within the body of said electrically operated control valve.

9. The system according to claim 1 , further comprising an auxiliary chamber in communication with said volume of pressurized fluid and defined by a movement of a movable member, the position of the movable member being controlled by an electrically driven actuator, said electronic control unit being programmed for controlling said actuator so as to cause a displacement thereof which creates the aforesaid additional volume when the pressure in the volume of pressurized fluid exceeds said maximum threshold value.

10. The system according to claim 9 , wherein the threshold pressure value that triggers the actuator is varied as a function of the operating conditions.

11. The system according to claim 9 , wherein said electronic control unit controls the actuator of said oscillation dampening device in a closed-loop mode, on the basis of a signal from at least one pressure sensor adapted to detect the pressure in the volume of pressurized fluid.

12. The system according to claim 9 , wherein said electronic control unit is programmed for controlling the actuator of the movable member of the oscillation dampening device in an open-loop mode, on the basis of stored maps, as a function of the operating conditions of the engine and/or of the system for variable actuation of the engine valve.

13. The system according to claim 9 , wherein the communication of the aforesaid auxiliary chamber with the volume of pressurized fluid is a permanently opened communication.

14. The system according to claim 9 , wherein said auxiliary chamber and said movable member are provided within the body of the oscillation dampening member, said body comprising a separate element.

15. The system according to claim 9 , wherein said auxiliary chamber and said movable member are provided within the body of said slave piston.

16. The system according to claim 9 , wherein said auxiliary chamber and said movable member are provided within the body of said master piston.

17. The system according to claim 9 , wherein said auxiliary chamber and said movable member are provided within the body of said electrically operated control valve.

Assignees

• Fiat Ricerche
• Fiat Ricerche

Inventors

• Stucchi Sergio
• Ricco Raffaele
• Gargano Marcello
• De Michele Onofrio
• Mazzarella Carlo

Classifications

• F01L1/25 Primary

  between cam and valve stem · CPC title

• F01L2810/03

  Reducing vibration · CPC title

• F01L2810/04

  Reducing noise · CPC title

• F01L2001/0537

  Double overhead camshafts [DOHC] · CPC title

• F02D13/0207

  changing valve lift or valve lift and timing · CPC title