Internal-combustion engine having a system for variable actuation of the intake valves, provided with an electrically actuated valve having two ways and three positions

Patent metadata

Field	Value
Publication number	US-9416691-B2
Application number	US-201414334955-A
Country	US
Kind code	B2
Filing date	Jul 18, 2014
Priority date	Aug 1, 2013
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

An internal-combustion engine includes a system for variable actuation of intake valves, including a control valve for each cylinder, which controls communication of a pressurized-fluid chamber with a discharge channel. The control valve has at least three different positions, namely, a first completely open position, a second partially open position, and a third completely closed position. Electronic control means are programmed for keeping the control valve in its closed position in operating stages in which the intake valve must remain coupled to the respective cam and for bringing the control valve from its completely closed position to its partially open position or to its completely open position in operating stages in which the intake valve must be uncoupled from the respective cam, selection between the first position and said second position of the control valve being made as a function of one or more operating parameters of the engine.

First claim

What is claimed is:

1. An internal-combustion engine, comprising for each cylinder of the engine:
a combustion chamber;
at least one intake duct and at least one exhaust duct opening out into said combustion chamber;
at least one intake valve and at least one exhaust valve associated to said intake and exhaust ducts and provided with respective return springs that push the at least one intake valve and the at least one exhaust valve toward a closed position; and
a camshaft for actuating the intake valves by means of respective tappets;
wherein said at least one intake valve is governed by a respective tappet of the tappets against an action of the return spring by interposition of hydraulic means including a pressurized-fluid chamber, facing which is a pumping plunger connected to the respective tappet of the valve, said pressurized-fluid chamber being capable of communicating with a chamber of a hydraulic actuator associated to said at least one intake valve;
a single electrically actuated control valve associated to said at least one intake valve of each cylinder and capable of setting said pressurized-fluid chamber in communication with a discharge channel in order to uncouple said at least one intake valve from the respective tappet and cause rapid closing of said at least one intake valve by action of the respective return spring;
electronic control means, for controlling said control valve to vary an instant of opening and/or the instant of closing and a lift of each intake valve as a function of one or more operating parameters of the engine,
the electrically actuated control valve associated to each cylinder being a two-way valve having at least three different operating positions, comprising:
a first operating position in which the control valve is completely open;
a second operating position in which the control valve is only partially open; and
a third operating position in which the control valve is completely closed, and
said electronic control means programmed for:
keeping said control valve in said third, completely closed, position in operating stages in which said at least one intake valve must remain coupled to the respective cam,
bringing said control valve from said third, completely closed, position to said second, partially open, position or to said first, completely open, position in operating stages in which said at least one intake valve must be uncoupled from the respective cam, the selection between said first position and said second position of the control valve being made as a function of one or more operating parameters of the engine.

2. The engine according to claim 1 , wherein selection between said first position and said second position is made as a function of one or more of the following parameters: engine r.p.m., engine load, a value of temperature of the engine, a temperature of a fluid used in said hydraulic means, a viscosity of said fluid.

3. The engine according to claim 1 , wherein:
said electrically actuated control valve includes a first operative port, a second operative port, a poppet element co-operating with a valve seat set hydraulically between the first operative port and the second operative port, and an electrical-actuation device for displacing the poppet element between a first operating position, a second operating position, and a third operating position, corresponding to the operating positions of the control valve,
wherein:
in the first operating position, an area of passage for a hydraulic fluid defined between said valve seat and said poppet element has a maximum value;
in the second operating position, said area of passage is partialized and has a value lower than said maximum value;
in the third operating position, said poppet element is in contact with said valve seat and the area of passage has a substantially zero value, so that the first operative port is isolated from the second operative port,
wherein:
the poppet element is moveable from the first operating position to the second operating position by a first electrical command imparted on said electrical-actuation device against the resisting action a first elastic element,
the poppet element is movable from the second operating position to the third operating position by a second electrical command imparted on said electrical-actuation device against the resisting action said first elastic element and of a second elastic element.

4. The engine according to claim 3 , wherein said poppet element is movable along a main axis of said valve and is set coaxially thereto.

5. The engine according to either claim 3 , wherein said poppet element is hydraulically balanced.

6. The engine according to claim 3 , wherein said first elastic element and said second elastic element have different stiffnesses.

7. The engine according to claim 3 , wherein said electrical-actuation device is an electromagnet and in that said first and second electrical commands correspond to two different levels of the supply current of the electromagnet.

8. The engine according to claim 7 , wherein said control valve further includes a second spacer ring bearing upon said elastic positioning ring and in turn having a stop surface for a movable core of said electromagnet, said movable core being axially constrained to said shank and being able to slide in a cavity within which said first elastic element is housed, bearing upon the shank.

9. The engine according to claim 3 , wherein said electrical-actuation device includes a piezoelectric linear actuator.

10. The engine according to claim 3 , wherein said electrical-actuation device includes a magnetostrictive linear actuator.

11. The engine according to any claim 1 , wherein said first elastic element and said second elastic element have identical stiffnesses.

12. The engine according to claim 1 , wherein said control valve includes a body having a cylindrical tubular shape, provided on which are said first operative port and said second operative port and mounted axially movable within which is said poppet element, wherein said electrical-actuation device is fixed to said body.

13. The engine according to claim 12 , wherein said poppet element includes a head and a shank, wherein the head is slidably mounted within a first section of a through hole of said body having a first diameter, and said shank traverses a second section of said through hole of said body.

14. The engine according to claim 13 , wherein housed in said second section of said axial hole of the body are:
a first spacer ring bearing upon a shoulder between said first section and said second section of the through hole; and
said second elastic element bearing upon said first spacer ring and upon an axially fixed elastic positioning ring.

Assignees

• Fiat Ricerche

Inventors

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

Classifications

• F01L13/0031 Primary

  by modification of tappet or pushrod length · CPC title

• F01L2001/3443

  Solenoid driven oil control valves · CPC title

• F01L1/14

  Tappets {(hydraulic tappets for automatically adjusting or compensating clearance F01L1/24)}; Push rods · CPC title

• F16K31/0655 Primary

  Lift valves · CPC title

• F01L9/025

  Mechanical Engineering · mapped topic