METHOD FOR CONTROLLING A MOTOR-VEHICLE PROVIDED WITH A PROPULSION SYSTEM OF THE "MILD-HYBRID" TYPE

• US 20140190426A1
• Filed: 07/05/2012
• Published: 07/10/2014
• 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 9,181,914 B2
• Time in Patent Office: Days
• US Class Current: 123/2
• CPC Class Codes: B60K 6/22 characterised by apparatus, components or means specially adapted for HEVs
• CPC Class Codes: B60K 6/24 characterised by the combustion engines
• CPC Class Codes: B60K 6/485 Motor-assist type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 2510/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2510/101 Transmission neutral state
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/0633 Inlet air flow rate
• CPC Class Codes: B60W 30/18072 Coasting
• CPC Class Codes: B60Y 2300/525 by reducing drag torque, e.g. by closing valves to reduce pumping
• 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 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 13/0226 : changing valve lift or valve lift and timing
• CPC Class Codes: F02D 13/0261 : Controlling the valve overlap
• CPC Class Codes: F02D 2041/001 : for engines with variable valve actuation
• CPC Class Codes: F02D 29/02 : peculiar to engines driving vehicles; peculiar to engines driving variable pitch propellers
• CPC Class Codes: F02D 41/0002 : Controlling intake air
• CPC Class Codes: F02D 41/042 : for stopping the engine
• CPC Class Codes: F02D 41/123 : the fuel injection being cut-off
• 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: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles

Abstract

In a vehicle provided with a power propulsion system of the mild-hybrid type, a BAS unit —including an electric machine connected through a belt transmission to the shaft of an internal combustion engine—is exploited as the only propulsion engine of the vehicle in given operating conditions. The internal combustion engine is provided with a system for variable actuation of the intake valves which is controlled to reduce the pumping losses of the internal combustion engine in the phase in which such engine is in cut-off condition and it is driven by the aforementioned BAS unit. It is also provided for that the system for variable actuation of the intake valves be controlled to temporarily increase the pumping losses of the internal combustion engine in a phase in which it is required to accelerate the switching off of the engine.

Claims

1. Method for controlling a motor vehicle of the type comprising:

an internal combustion engine having a drive shaft with an output end connected through a transmission to at least one pair of wheels of the motor vehicle and an upstream end connected to one or more auxiliary devices through a belt transmission,

a BAS unit comprising an electric machine connected to said upstream end of the drive shaft through said belt transmission and controlled to operate as an electrical power generator, as an electric motor for starting the internal combustion engine and as an auxiliary engine for the propulsion of the motor vehicle, additionally to the internal combustion engine,

wherein;

in given engine operating conditions said BAS unit is used as the only propulsion engine of the motor vehicle, maintaining the internal combustion engine in a cut-off condition and using the drive shaft as a simple transmission shaft,

said internal combustion engine is provided with a system for variable actuation of the intake valves, and

in the aforementioned operating conditions wherein the BAS unit used as the only propulsion engine, the system for variable actuation of the intake valves of the internal combustion engine is controlled to vary the opening time and/or the closing time and/or the lift of the intake valves, so as to reduce the losses due to a pumping effect which occur within the internal combustion engine when it is driven in rotation by said BAS unit in a cut-off condition.

2. Method according to claim 1, wherein in the aforementioned operating conditions in which the BAS unit is used as the only propulsion engine, the system for variable actuation of the intake valves of the internal combustion engine is controlled to close the intake valves in advance with respect to a conventional intake cycle.

3. Method according to claim 1, wherein said system for variable actuation of the intake valves is controlled so as to open the intake valves 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.

4. Method according to claim 1, wherein 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, wherein 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 decouple the intake valve from the respective cam and cause the closure thereof due to said return spring means.

5. 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 so as to differently actuate the same intake valve over time as a function of the engine operating conditions and detected by an electronic control unit through a plurality of sensors.

6. Method according to claims 1, wherein said operating condition, in which the BAS unit is used as the only propulsion engine, is activated with the vehicle stationary, to perform a vehicle start.

7. Method according to claim 1, wherein said operating condition, wherein the BAS unit is used as the only propulsion engine, is activated with the motor vehicle moving , when the operating conditions of the vehicle, of the engine and of the electrical system allow it.

8. Method according to claim 1, further comprising a freewheel operating mode, with the internal combustion engine off and the wheels of the vehicle not connected to the propulsion system.

9. Method according to claim 8, wherein when it is activated the freewheel operating mode, with the internal combustion engine in a run-down mode, the following strategies are activated:

if the speed of the internal combustion engine is above a minimum-run threshold, the intake valves are controlled so as to temporarily minimise the pumping losses to increase the engine run-down time, to allow a possible freewheel output with fuel re-injection (thus avoiding a BAS or starter engine start, if a starter is also provided for besides the BAS, i.e. an electric start motor);

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

the intake valves are controlled so as to temporarily minimise the pumping losses to increase the engine run-down time, to prepare to restart the engine with the engine moving;

the intake valves are controlled so as to temporarily maximise 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.

10. Method according to claim 1, wherein said operating phase, in which the BAS unit is used as the only propulsion engine of the motor vehicle, is started on the basis of a signal selected from among:

an accelerator pedal position signal,

a brake pedal position signal,

a clutch condition signal,

a signal indicating the speed of the vehicle,

a signal indicating the engaged gear, in case of a servo-assisted gearbox, or engagement of a neutral gear, in case of a manual actuation gearbox.

11. Method according to claim 1, wherein the system for variable actuation of the intake valves is controlled to reduce the pumping losses even in the phase in which said BAS unit is used as a starter, to start the internal combustion engine.

12. Method according to claim 1, wherein when it is activated the aforementioned operating condition in which said BAS unit is used as the only propulsion engine of the motor vehicle, the switching off of the engine is accelerated, with the aim of being able to promptly restart it in case of a change-of-mind of the driver.

13. Method according to claim 12, wherein the acceleration of the switching off is obtained by temporarily increasing the pumping losses of the internal combustion engine, by controlling the system for variable actuation of the intake valves such to cause a delayed opening, or a total absence of opening, of the intake valves.

14. Method according to claim 1, wherein the system for variable actuation of the intake valves of the internal combustion engine is controlled so as to reduce the pumping losses even in engine cut-off conditions in which the BAS unit is used as a regeneration unit