Method for estimating and controlling the intake efficiency of an internal combustion engine

Patent metadata

Field	Value
Publication number	US-11384701-B2
Application number	US-202117379332-A
Country	US
Kind code	B2
Filing date	Jul 19, 2021
Priority date	May 15, 2019
Publication date	Jul 12, 2022
Grant date	Jul 12, 2022

Abstract

A method for calculating the mass of an overlap gaseous flow (MOVL), wherein the exhaust pressure is higher than the intake pressure, or in the case of scavenging (SCAV), wherein the intake pressure is higher than the exhaust pressure. The overlap gaseous flow (MOVL) is the flow which flows, in overlap conditions, through the intake valve and the exhaust valve of a cylinder of an internal combustion engine. At least one intake valve is driven so as to vary the lift (H) of the intake valve in controlled manner. The overlap condition is a condition in which the intake valve and the exhaust valve are both at least partially open. The method comprises calculating the mass of the gaseous flow (MOVL) which flows through the intake valve and the exhaust valve on the basis of the relation:MOVL=PERM*β(P/P0,n)*P0/P0_REF*(T0_REF/T0)1/2/n.

First claim

The invention claimed is:

1. A method for calculating the mass of an overlap gaseous flow (M OVL ), in the case of exhaust gas internal recirculation (EGRi), wherein the exhaust pressure is higher than the intake pressure, or in the case of scavenging (SCAV), wherein the intake pressure is higher than the exhaust pressure,
said overlap gaseous flow (M OVL ) being the flow which flows, in overlap conditions, through the intake valve and the exhaust valve of a cylinder of an internal combustion engine comprising a number of cylinders, wherein each of the cylinders is connected to an intake manifold from which it receives fresh air through at least one respective intake valve, and to an exhaust manifold into which it introduces the exhaust gases generated by the combustion through at least one respective exhaust valve, wherein the at least one intake valve is driven so as to vary the lift (H) of the intake valve in controlled manner,
said overlap condition being a condition in which said intake valve and said exhaust valve are both at least partially open,
wherein the method comprises:
calculating the mass of the gaseous flow (M OVL ) which flows through the intake valve and the exhaust valve on the basis of the relation:
M OVL =PERM*β( P/P 0 ,n )* P 0 /P 0_REF *( T 0_REF /T 0 ) 1/2 /n,

where PERM is the hydraulic permeability associated to the overlap condition;
n is the engine speed;
β(P/P 0 ,n) is a compression factor of a flow through an orifice, depending on the ratio between the pressures downstream and upstream of the orifice and on the engine speed (n);
and where:
under a condition of internal recirculation of the exhausted gases, P 0 is the exhaust pressure, P 0_REF is a reference exhaust pressure value and P is the intake pressure, T 0 is the temperature of the exhaust gases, T 0_REF is a reference value for the temperature of the exhaust gases T 0 ; and/or
under a condition of scavenging, P 0 is the intake pressure, P 0_REF is a reference intake pressure value and P is the exhaust pressure, T 0 is the temperature of the intake gases, T 0_REF is a reference value for the temperature of the intake gases;
and wherein said hydraulic permeability (PERM) is calculated based on a first function and a second function, wherein the first function depends on the engine speed (n) and on the duration of the overlap condition (OVL) during which the intake valve and the exhaust valve are simultaneously opened, and the second function depends on the lift (H) and the engine speed (n).

2. The method as set forth in claim 1 , wherein said hydraulic permeability (PERM) associated to the overlap condition is calculated using the following relation:
PERM= A ( OVL,n )* fo ( H,n )* G ( g,n ),
where A(OVL,n) is said first function depending on the engine speed (n) and on the duration of the overlap condition or intersecting step (OVL) during which the intake valve and the exhaust valve are simultaneously opened;
fo(H,n) is said second function dependent on the lift (H) and the engine speed (n); and
G (g,n) is a third function representative of the center of gravity of the overlap region or intersecting region, depending on the engine speed (n) and depending on a geometrical parameter (g) representative of the angular deviation between an upper dead point and the center of gravity (G) of the overlap region.

3. The method as set forth in claim 1 , wherein said intake pressure, engine speed (n) and lift (H) are measured quantities, and said exhaust pressure is an estimated quantity or measured quantity.

4. The method as set forth in claim 1 , wherein P 0_REF is a reference pressure upstream of the passage between intake manifold and exhaust manifold, through the intake valve and the exhaust valve, in overlap condition.

5. The method as set forth in claim 1 , wherein:
under a condition of internal recirculation of the exhausted gases, T 0 is the temperature of the exhaust gases upstream of the exhaust valve, in overlap condition;
and/or, under a condition of scavenging, T 0 is the temperature of the intake gases upstream of the intake valve, in overlap condition;
and wherein said temperature of the exhaust gases upstream of the exhaust valve and/or of the intake gases upstream of the intake valve, in overlap condition, are measured or estimated quantities.

6. The method as set forth in claim 1 , comprising, when the engine operates under the condition of exhaust gas internal recirculation (EGRi), wherein the exhaust pressure (P EXH ) is greater than the intake pressure (P), the further step of:
calculating a combustion chamber volume (Vcc) of the cylinder based on a first map f e (TVC, n) which is a function of a first parameter (TVC) and of the engine rotation speed (n), on a second map g e (OVL, n) which is a function of a second parameter (OVL) and of the engine rotation speed (n), and on a third map h e (H,n) which is a function of the lift (H) and of the engine rotation speed (n),
wherein said first parameter (TVC) is alternatively equal to the closing delay angle (EVC) of the exhaust valve or to the maximum between zero and the minimum value among the closing delay angle (EVC) of the exhaust valve and the value of the opening advance angle (IVO) of the intake valve multiplied by −1, and
wherein said second parameter (OVL) is representative of the duration of the intersecting step between the intake and exhaust curves and is defined as the sum of the exhaust valve closing delay angle (EVC) and the intake valve opening advance angle (IVO).

7. The method as set forth in claim 6 , wherein the combustion chamber volume (V cc ) is calculated using the formula:
V cc =f e ( TVC,n )* g e ( OVL,n )* h e ( H,n ),
where f e , g e , h e are known functions.

8. The method as set forth in claim 1 , wherein, under a condition of exhaust gas internal recirculation (EGRi) wherein the exhaust pressure (P EXH ) is greater than the intake pressure (P), the method comprises the further step of:
calculating the total mass (M EGRi ) of gas present in the cylinder as the sum of an estimated mass (M EXH_EGR ) of exhaust gases in the combustion chamber under conditions of exhaust gas internal recirculation and of said estimated mass of gaseous flow (M OVL ) which flows through the overlap or intersection step, that is the mass of gaseous flow which flows from the exhaust to the intake through the intake valve and the exhaust valve and which is then sucked back into the cylinder through the intake valve during the intake step,
according to the formula:
M EGRi =M OVL +M EXH_EGR.

9. The method as set forth in claim 8 , wherein the estimated mass (M EXH_EGR ) of exhausted gases in the combustion chamber under conditions of exhaust gas internal recirculation is calculated by using the following relation:
M EXH_EGR =( P EXH *V cc )/( R*T EXH ),
where P EXH is the gas flow pressure detected in the exhaust;
T EXH is the gas flow temperature detected in the exhaust;
V cc is the estimated or calculated volume of the combustion chamber of the cylinder; and
R is the constant of fresh air and/or exhaust gas mix.

10. The method as set forth in claim 1 , wherein if the engine may operate under a scavenging condition (SCAV) wherein the intake pressure is greater than the exhaust pressure, thus causing the intake of fresh air which carries away the residual exhaust gases in the combustion chamber, and the method comprises the further step of:
calculating a combustion chamber volume (V cc ) of the cylinder based on a first map f s (TVC, n) which is a function of a first parameter (TVC) and of the engine rotation speed (n), based on a second map

Assignees

• Marelli Europe Spa

Inventors

• Panciroli Marco

Classifications

• F02D13/0261

  Controlling the valve overlap · CPC title

• F02D13/023

  the change of valve timing is caused by the change in valve lift, i.e. both valve lift and timing are functionally related · CPC title

• F02D41/0072 Primary

  Estimating, calculating or determining the EGR rate, amount or flow (sensors in EGR systems F02M26/45) · CPC title

• F02M35/104

  Intake manifolds · CPC title

• F02D41/0062

  Estimating, calculating or determining the internal EGR rate, amount or flow · CPC title