METHOD FOR CONTROLLING A MOTOR-VEHICLE PROVIDED WITH AN INTERNAL COMBUSTION ENGINE HAVING A SYSTEM FOR VARIABLE ACTUATION OF THE INTAKE VALVES

• US 20140202423A1
• Filed: 07/05/2012
• Published: 07/24/2014
• Est. Priority Date: 10/03/2011
• Status: Active Grant

• Current Assignee: C.R.F. Societa Consortile Per Azioni
• Original Assignee: C.R.F. Societa Consortile Per Azioni
• Inventors: Carvignese, Cosimo, Finizio, Roberto, Borean, Fabio, Cuniberti, Marco
• Granted Patent: US 9,429,080 B2
• Time in Patent Office: Days
• US Class Current: 123/321
• CPC Class Codes: F01L 1/08 Shape of cams
• CPC Class Codes: F01L 1/185 Overhead end-pivot rocking arms
• CPC Class Codes: F01L 1/267 with means for varying the timing or the lift of the valves
• CPC Class Codes: F01L 13/0015 for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
• CPC Class Codes: F01L 13/0026 by means of an eccentric
• CPC Class Codes: F01L 2013/118 Valve lift
• CPC Class Codes: F01L 2305/00 Valve arrangements comprising rollers
• CPC Class Codes: F01L 2820/01 Absolute values
• CPC Class Codes: F01L 9/14 the volume of the chamber being variable, e.g. for varying the lift or the timing of a valve
• CPC Class Codes: F02D 13/0207 changing valve lift or valve lift and timing
• CPC Class Codes: F02D 13/0215 changing the valve timing only
• CPC Class Codes: F02D 13/0226 changing valve lift or valve lift and timing
• CPC Class Codes: F02D 13/0238 by shifting the phase, i.e. the opening periods of the valves are constant
• CPC Class Codes: F02D 13/0265 Negative valve overlap for temporarily storing residual gas in the cylinder
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 41/042 for stopping the engine
• CPC Class Codes: F02D 41/065 at hot start or restart F02D41/067 takes precedence
• CPC Class Codes: F02M 26/01 Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages
• CPC Class Codes: F02N 11/003 said electric motor being also used as a drive for auxiliaries, e.g. for driving transmission pumps or fuel pumps during engine stop
• CPC Class Codes: F02N 11/0844 with means for restarting the engine directly after an engine stop request, e.g. caused by change of driver mind
• CPC Class Codes: F02N 19/004 : Aiding engine start by using decompression means or variable valve actuation
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

A motor vehicle provided with an internal combustion engine having a system for variable actuation of the intake valves has a phase of activation of an operating mode with the engine off and the vehicle moving, in which the fuel supply to the engine is cut-off. After the cut-off of the fuel supply to the engine, the system for variable actuation of the intake valves is controlled to vary the opening time and/or closing time and/or the lift of the intake valves so as to control the losses due to the pumping effect which occur within the engine in cut-off condition.

Claims

1. Method for controlling a motor vehicle provided with an internal combustion engine having a system for variable actuation of intake valves,

wherein said method comprises a phase of activation of an operating mode with the engine off and the vehicle moving, in which the fuel supply to the engine is cut-off,

and in that after the cut-off of the fuel supply to the engine the system for variable actuation of the intake valves is controlled to vary the opening time and/or closing time and/or the lift of the intake valves so as to control the losses due to a pumping effect which occur within the engine in said cut-off condition, according to one of the following strategies:

if the speed of the engine is above a minimum-run threshold, the intake valves are controlled so as to temporarily minimize the pumping losses, to increase an engine run-down time required to reach a stop of a drive shaft of the engine, so as to allow a possible change-of-mind of the driver, and a restart of the engine by reactivating the fuel supply;

if the speed of the engine is below the minimum-run threshold one of the following strategies are actuated;

if the motor vehicle is provided with an electric start motor capable of operating with the internal combustion engine moving, the intake valves are controlled so as to temporarily minimize the pumping losses to increase the run-down time so as to be able to restart the internal combustion engine when it is still moving;

if the motor vehicle is provided with an electric start motor capable of operating only when the internal combustion engine is stationary, the intake valves are controlled so as to temporarily maximize the pumping losses to reduce the engine run-down time, with the aim of allowing a possible engine restart, with the engine stationary, as soon as possible.

2. Method according to claim 1, wherein the system for variable actuation of the intake valves is also controlled to reduce the pumping losses in the phase in which the internal combustion engine is started through an electric start motor.

3. Method according to claim 1, in which the internal combustion engine is provided with a system for variable actuation of the engine valves comprising at least one camshaft connected to the drive shaft, in which each intake valve is controlled by a respective tappet actuated by a respective cam of said camshaft, against the action of spring means associated to each intake valve which return the intake valve towards a closed position, and in which said tappet is connected to said intake valve through hydraulic actuation means, comprising a pressure hydraulic chamber which can be connected to an exhaust channel through an electronically controlled solenoid valve, so as to uncouple the intake valve from the respective cam and cause the closing thereof due to said return spring means.

4. Method according to claim 1, wherein said system for variable actuation of the intake valves is controlled so as to differently actuate intake valves associated to different cylinders and/or so as to differently actuate the same intake valve over time as a function of the engine operating conditions, detected by an electronic control unit through a plurality of sensors.

5. Method according to claim 1, wherein said vehicle is provided, additionally to the internal combustion engine, with an electric motor kinematically connected to the internal combustion engine, upstream of the internal combustion engine such that the internal combustion engine kinematically interposed between the electric motor and the driven wheels of the vehicle and in that there is provided an e-motoring phase in which the electric motor is used as the only motor vehicle propulsion engine, with the internal combustion engine in cut-off condition, and in that in such e-motoring phase the system for variable actuation of the intake valves is controlled to reduce the pumping losses of the engine.

6. Method according to claim 1, wherein the increase of the pumping losses of the internal combustion engine is obtained by controlling the system for variable actuation of the intake valves such to cause a delayed opening of the intake valves with respect to a conventional intake cycle, or a total absence of opening of the intake valves.

7. Method according to claim 1, wherein the reduction of the pumping losses of the internal combustion engine is obtained by controlling the system for variable actuation of the intake valves such to cause a closing of the intake valves in advance with respect to a conventional intake cycle.

8. Method according to claim 7, wherein said system for variable actuation of the intake valves is controlled so as to open the intake valves (5) during a phase which—

during the normal operation of the engine—

corresponds to the exhaust phase, with the aim of obtaining a recirculation—

in each cylinder—

of the exhaust gases produced in the engine immediately before the cut-off phase.