COMBUSTION MODE SWITCHING WITH A TURBOCHARGED/SUPERCHARGED ENGINE

• US 20130125544A1
• Filed: 11/16/2012
• Published: 05/23/2013
• Est. Priority Date: 11/17/2011
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH, Robert Bosch LLC (Robert Bosch GmbH)
• Original Assignee: Robert Bosch GmbH
• Inventors: Mond, Alan, Jiang, Li
• Granted Patent: US 9,140,199 B2
• Time in Patent Office: Days
• US Class Current: 60/611
• CPC Class Codes: F01L 1/34 characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
• CPC Class Codes: F02B 1/14 Methods of operating
• CPC Class Codes: F02B 29/04 Cooling of air intake supply
• CPC Class Codes: F02B 37/04 Engines with exhaust drive and other drive of pumps, e.g. with exhaust-driven pump and mechanically-driven second pump
• CPC Class Codes: F02B 37/12 Control of the pumps
• CPC Class Codes: F02B 37/183 Arrangements of bypass valves or actuators therefor
• CPC Class Codes: F02B 39/04 Mechanical drives; Variable-gear-ratio drives non-mechanical pump drives having variable gear ratio F02B39/08
• CPC Class Codes: F02B 39/12 Drives characterised by use of couplings or clutches therein using fluid slip couplings for varying gear ratio F02B39/08
• CPC Class Codes: F02D 13/0207 changing valve lift or valve lift and timing
• CPC Class Codes: F02D 2021/083 controlling exhaust gas recirculation electronically
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 23/00 Controlling engines characterised by their being supercharged
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• CPC Class Codes: F02D 41/0057 Specific combustion modes combustion modes per se F02D41/3017
• CPC Class Codes: F02D 41/006 using internal EGR control of valve overlap for internal EGR F02D13/0261; arrangements for internal EGR F02M26/01
• CPC Class Codes: F02D 41/3035 a mode being the premixed charge compression-ignition mode
• CPC Class Codes: F02D 41/3041 with means for triggering compression ignition, e.g. spark plug
• CPC Class Codes: F02D 41/3064 with special control during transition between modes
• CPC Class Codes: F02M 26/05 High pressure loops, i.e. wherein recirculated exhaust gas is taken out from the exhaust system upstream of the turbine and reintroduced into the intake system downstream of the compressor
• CPC Class Codes: F02M 26/23 Layout, e.g. schematics
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 : Engine management systems

Abstract

A method for switching between low- and high-dilution combustion modes in an internal combustion engine having an intake passage with an exhaust-driven turbocharger, a crankshaft-driven positive displacement supercharger downstream of the turbocharger and having variable boost controllable with a supercharger bypass valve, and a throttle valve downstream of the supercharger. The current combustion mode and mass air flow are determined. A switch to the target combustion mode is commanded when an operating condition falls within a range of predetermined operating conditions. A target mass air flow to achieve a target air-fuel ratio corresponding to the current operating condition and the target combustion mode is determined. The degree of opening of the supercharger bypass valve and the throttle valve are controlled to achieve the target mass air flow. The amount of residual exhaust gas is manipulated.

Claims

1. A method for switching from a current combustion mode, which is either of a low-dilution combustion mode and a high-dilution combustion mode, to a target combustion mode, which is the other of the low-dilution and high-dilution combustion modes in an internal combustion engine having an intake passage with an exhaust-driven turbocharger, a crankshaft-driven positive displacement supercharger downstream of the turbocharger and having variable boost output controllable with a supercharger bypass valve, and a throttle valve downstream of the supercharger, the method comprising:

determining the current combustion mode;

determining current mass air flow;

commanding a combustion mode switch to the target combustion mode when a current operating condition falls within a range of predetermined operating conditions;

determining a target mass air flow amount to achieve a target air-fuel ratio corresponding to the current operating condition and the target combustion mode;

controlling the degree of opening of both the supercharger bypass valve and the throttle valve to achieve the target mass air flow; and

manipulating the amount of residual exhaust gas.

2. The method of claim 1, wherein the current combustion mode is stoichiometric spark ignition (SI) and the target combustion mode is the high-dilution combustion mode of homogeneous charge compression ignition (HCCI) combustion, and wherein manipulating the amount of residual exhaust gas is carried out by adjusting the exhaust valve phasing, the method further comprising transitioning through a lean SI transition mode by reaching the target mass air flow prior to adjusting the exhaust valve phasing, and the switch into HCCI is completed by reducing the exhaust lift amount to stage the necessary in-cylinder conditions for auto-ignition within a predetermined number of engine cycles.

3. The method of claim 1, wherein manipulating the amount of residual exhaust gas includes adjusting the phasing of exhaust valve actuation.

4. The method of claim 3, wherein the spark ignition device is prevented from initiating combustion within a predetermined number of engine cycles after the phasing of exhaust valve actuation is adjusted.

5. The method of claim 1, wherein controlling the degree of opening of both the supercharger bypass valve and the throttle valve to achieve the target mass air flow includes controlling the throttle valve to move to or remain at a wide open position.

6. The method of claim 1, wherein the high-dilution combustion mode is homogeneous charge compression ignition (HCCI) combustion in which a spark ignition device of the engine does not initiate combustion, and wherein switching between the current combustion mode and the target combustion mode includes transitioning through a transition combustion mode.

7. The method of claim 6, wherein the transition combustion mode includes one of a lean spark ignition (SI) combustion mode and a stoichiometric HCCI combustion mode.

8. The method of claim 7, further comprising selecting one of the lean SI combustion mode and the stoichiometric HCCI mode based on the determination of the target mass air flow amount.

9. The method of claim 6, wherein the transition combustion mode is spark-assisted compression ignition (SACI).

10. The method of claim 1, wherein the high-dilution combustion mode is spark-assisted compression ignition (SACI).

11. The method of claim 1, further comprising adjusting at least one of intake valve timing and duration in conjunction with controlling the degree of opening of both the supercharger bypass valve and the throttle valve to achieve the target mass air flow.

12. A method for switching from low-dilution combustion mode to a high-dilution combustion mode, in an internal combustion engine having an intake passage with an exhaust-driven turbocharger, a crankshaft-driven positive displacement supercharger downstream of the turbocharger and having variable boost output controllable with a supercharger bypass valve, and a throttle valve downstream of the supercharger, the method comprising:

switching from a high lift intake valve setting to a low lift intake valve setting;

determining a target mass air flow amount to achieve a target air-fuel ratio for the high-dilution combustion mode under a current operating condition;

controlling the degree of opening of both the supercharger bypass valve and the throttle valve to achieve the target mass air flow after switching to the low lift intake valve setting to achieve a transitional combustion mode;

operating in the transitional combustion mode while adjusting the phasing of exhaust valve actuation to increase residual exhaust gas;

switching from a high lift exhaust valve setting to a low lift exhaust valve setting after the phasing of the exhaust valve actuation is adjusted; and

commencing auto-ignition within a predetermined number of engine cycles after switching to the low lift exhaust valve setting.

13. The method of claim 12, wherein controlling the degree of opening of both the supercharger bypass valve and the throttle valve to achieve the target mass air flow includes controlling the throttle valve to move to a wide open position.

14. The method of claim 12, wherein the low-dilution combustion mode is stoichiometric spark ignition (SI), and the high-dilution combustion mode is homogeneous charge compression ignition (HCCI).

15. The method of claim 12, wherein the transitional combustion mode includes one of a lean spark ignition (SI) combustion mode and a stoichiometric homogeneous charge compression ignition (HCCI) combustion mode.

16. The method of claim 15, further comprising selecting one of the lean SI combustion mode and the stoichiometric HCCI mode based on the determination of the target mass air flow amount.

17. The method of claim 12, wherein the transitional combustion mode is spark-assisted compression ignition (SACI).

18. The method of claim 12, further comprising manipulating the amount of residual exhaust gas.

19. The method of claim 12, further comprising adjusting at least one of intake valve timing and duration in conjunction with controlling the degree of opening of both the supercharger bypass valve and the throttle valve to achieve the target mass air flow.