CONTROLLING AN INTERNAL COMBUSTION ENGINE

Abstract

A method and device for controlling a supercharged internal combustion engine is disclosed. An oxygen charge of a catalytic converter of the internal combustion engine is determined. A valve overlap of the internal combustion engine is increased from a lower valve overlap value to an upper valve overlap value. Increasing the valve overlap and/or for at least one phase of the increase, a control value for increasing an air-fuel ratio in at least one cylinder of the internal combustion engine is reduced as a function of the determined oxygen charge.

Claims

1-11. (canceled)

12. A method for controlling an internal combustion engine of a motor vehicle comprising: determining an oxygen charge of a catalytic converter of the internal combustion engine; and increasing a valve overlap of the internal combustion engine at a rate of change from a lower valve overlap value to an upper valve overlap value; and adjusting a control value as a function of the determined oxygen charge for at least one phase when increasing the valve overlap, wherein the control valve is associated with at least one of the valve overlap or an air-fuel ratio in at least one cylinder of the internal combustion engine.

13. The method according to claim 12, further comprising: controlling the internal combustion engine for a first determined oxygen charge such that the upper valve overlap value has a first overlap value; and controlling the internal combustion engine for a second determined oxygen charge which is greater than the first determined oxygen charge such that the upper valve overlap value has a second overlap value which is smaller than the first overlap value.

14. The method according to claim 12, further comprising controlling the internal combustion engine for a first determined oxygen charge such that the control value for the phase has a first ratio control value; and controlling the internal combustion engine for a second determined oxygen charge which is greater than the first determined oxygen charge such that the control value for the phase has a second ratio control value which is smaller than the first ratio control value.

15. The method according to claim 12, further comprising controlling the internal combustion engine for a first determined oxygen charge such that the rate of change has a first rate value; and controlling the internal combustion engine for a second determined oxygen charge which is greater than the first determined oxygen charge such that the rate of change has a second rate value which is smaller than the first rate value.

16. The method according to claim 12 further comprising: controlling the internal combustion engine for a first determined oxygen charge such that the upper valve overlap value has a first overlap value, the control value has a first ratio control value and the rate of change has a first rate valve; and controlling the internal combustion engine for a second determined oxygen charge, which is greater than the first determined oxygen charge, such that the upper valve overlap has a second overlap value which is smaller than the first overlap value, the control value for the phase has a second ratio control value which is smaller than the first ratio control value, and the rate of change has a second rate value which is smaller than the first rate value.

17. The method according to claim 12, further comprising: controlling the internal combustion engine for the phase such that the upper valve overlap value has a first overlap value when the determined oxygen charge does not exceed a preset limit value; and controlling the internal combustion engine for the phase such that the upper valve overlap value has a second overlap value which is smaller than the first overlap value when the determined oxygen charge exceeds the limit value.

18. The method according to claim 12, further comprising: controlling the internal combustion engine for the phase such that the control value has a first ratio control value when the determined oxygen charge does not exceed a preset limit value; and controlling the internal combustion engine for the phase such that the control value has a second ratio control value which is smaller than the first ratio control value when the determined oxygen charge exceeds the limit value.

19. The method according to claim 12, further comprising: controlling the internal combustion engine for the phase such that the rate of change a first rate value when the determined oxygen charge does not exceed a preset limit value; and controlling the internal combustion engine for the phase such that the rate of change has a second rate value, which is smaller than the first rate value when the determined oxygen charge exceeds the limit value.

20. The method according to claim 12, further comprising: controlling the internal combustion engine for the phase such that the upper valve overlap value has a first overlap value, the control value has a first ratio control value and the rate of change a first rate value when the determined oxygen charge does not exceed a preset limit value; and controlling the internal combustion engine for the phase such that the upper valve overlap value has a second overlap value which is smaller than the first overlap value, the control value has a second ratio control value which is smaller than the first ratio control value and the rate of change has a second rate value, which is smaller than the first rate value when the determined oxygen charge exceeds the limit value.

21. The method according to claim 12, further comprising increasing the valve overlap by a variable preset value.

22. The method according to claim 12, further comprising adjusting the control value by a variable preset value.

23. The method according to claim 12 further comprising determining the oxygen charge as a function of a duration of an unfired overrunning operation of the internal combustion engine.

24. The method according to claim 12, wherein determining the oxygen charge comprising measuring the oxygen charge with at least one sensor arranged downstream of the catalytic converter.

25. The method according to claim 12, wherein adjusting the control value comprises increasing a fuel control value for increasing a fuel supply.

26. A non-transitory computer-readable medium comprising a program code having instruction which when executed on a processor carrying out the method according to claim 12.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements.

[0049] FIG. 1 illustrates a part of an internal combustion engine according to the present disclosure; and

[0050] FIG. 2 illustrates a method for controlling the internal combustion engine according to the present disclosure.

DETAILED DESCRIPTION

[0051] The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description.

[0052] FIG. 1 shows a portion of an internal combustion engine according to the present disclosure. The engine includes a plurality of cylinders of same design or function, of which in FIG. 1 a cylinder 10 is exemplarily shown, wherein with respect to the other cylinders reference is made to the description of the former. In the cylinder 10, a piston 11 operates in the manner known per se. Through (at least) one inlet valve 12, in particular an intake gas (e.g. fresh air) can be fed to the cylinder 10, through (at least) one exhaust valve 14, exhaust gas from the cylinder 10 can be discharged into an exhaust passage 100, in which a three-way catalytic converter 30 is arranged downstream of the exhaust valve(s) 14.

[0053] In the exemplary embodiment, a fuel supply 20 is arranged upstream of or in front of the inlet valve(s) 12. Sensor 40 in the form of a lambda jump or broadband and probe is located upstream of catalytic converter 30. In a modification shown in interrupted lines, the fuel supply 20 can also be arranged in the cylinder or the cylinders 10.

[0054] The inlet valve(s) 12 are controllable by one or more adjustable inlet camshafts 13. The exhaust valve(s) 14 are controllable by one or more adjustable exhaust camshafts 15.

[0055] A control device in the form of an engine electronic control unit or ECU 1 is signal connected to the fuel supply 20 and a camshaft adjuster 16 for adjusting the camshafts 13, 15, in order to control these components. The engine ECU 1 is additionally signal connected to the lambda jump or broadband probe 40 and receives an output signal λ.sub.40 from the same.

[0056] The control device in the form of the engine ECU 1 carries out a method for controlling the internal combustion engine according to an embodiment of the present disclosure explained with reference to FIG. 2. In a step S10, the engine ECU 1 checks if a valve overlap, for example characterized by an adjusting angle of the camshaft adjuster 16, is to be increased, for example starting out from a current lower valve overlap value to an upper valve overlap value α.sub.2, d that is dependent on a rotational rate and load (demand) of the internal combustion engine. For as long as this is not the case (S10: “N”), the engine ECU 1 repeats the step S10.

[0057] If the valve overlap is to be (temporarily) increased to an upper valve overlap value α.sub.2, d (S10: “Y”), the engine ECU 1 in a step S20 determines the oxygen charge of the catalytic converter 30 or a charge value therefore. In an embodiment, the engine ECU 1 determines the oxygen charge or the charge value based on the output signal of the lambda jump or broadband probe 40. For example, a determined oxygen charge or charge value can be proportional to a reciprocal of an output voltage signal of the lambda jump or broadband probe 40, which for example below 200 mV can detect a high and/or above 600 mV a low oxygen charge.

[0058] In another embodiment, the engine ECU 1 in step S20 determines the oxygen charge of the catalytic converter 30 or the charge value therefor based on a duration t.sub.DFCO of an unfired or non-combusting overrunning operation of the internal combustion engine (“deceleration fuel cut-off”) preceding the increasing of the valve overlap. In particular, a determined oxygen charge or charge value can be proportional to a duration of an unfired or non-combusting overrunning operation of the internal combustion engine. Then, the engine ECU 1 checks in step S20 if the determined oxygen charge or the determined charge value exceeds an adjustable limit value (λ.sub.40<λ.sub.40, 0 or 1/λ.sub.40>1/λ.sub.40,0 or t.sub.DFCO>t.sub.DFCO, 0).

[0059] If this is the case, (S20: “Y”), the engine ECU 1 in a step S30 reduces a rate dα.sub.d/dt of the commanded increasing of the valve overlap for example a rate of the camshaft adjuster 16, by a preset offset Δα. Additionally, the engine ECU 1 reduces in steps S40-S70 a (first) control value for increasing an air-fuel ratio. For a commencement phase of increasing of the valve overlap carried out in step S70 up to the expiration (S40: “N”) of an adjustable period of time t.sub.s,0, it always increases and EQR or fuel control value EQR by a preset offset Δeqr.sub.0>0, so that the fuel supply 20 accordingly always supplies more fuel. The EQR or fuel control value EQR itself can be preset for example based on a load demand by the engine ECU 1 and/or a lambda control of the catalytic converter 30.

[0060] In a step S80, the engine ECU 1 checks if the temporary increasing of the oxygen charge of the catalytic converter 30 to the upper valve overlap value α.sub.2, d continues to be commanded. If this is no longer the case (S80: “N”), the engine ECU 1 or the method returns to step S10. In the case that the determined oxygen charge or the determined charge value exceeds the adjustable limit value (S20: “N”), the engine ECU 1 or the method skips step S30, i.e. does not slow down the commanded increasing, and just as after the expiration (S40: “N”) of the commencement phase also sets the offset Δeqr.sub.0 to zero, so that as a consequence the (first) control value for increasing air-fuel ratio is also no longer reduced by the offset Δeqr.sub.0 or conversely the EQR or fuel control value no longer increased by the offset Δeqr.sub.0. By way of this, the air-fuel ratio following the commencement phase or preset period of time t.sub.s, 0 of the increasing of the valve overlap or provided the oxygen charge of the catalytic converter 30 does not exceed the limit value, is no longer reduced (commanded by a constant offset).

[0061] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.