Method for Controlling Fuel Injection after Crankshaft Rotation

Abstract

A method for controlling fuel injection after engine startup, comprising performing the following steps: · a) determining or selecting a first injection curve with respect to a potential upcoming ignition or injection event for a particular cylinder, at or after synchronization; · b) determining whether there is sufficient time to implement the first injection curve; · c) if so, implementing the first injection curve with respect to the event.

Description

Technical Field

[0001] The present invention relates to controlling fuel injection in an internal combustion engine shortly after startup (i.e., after crank rotation). Background Art

[0002] When controlling fuel injection into the combustion chamber of an internal combustion engine, the fuel quantity and other injection parameters for an injection cycle are calculated at a time far in advance compared to the start of injection or spark. Far in advance is with respect to the actually defined crankshaft angular position (378°ca before ignition TDC). Other injection parameters that need to be calculated in advance are the segmented durations and / or timings of multiple injections in a single injection cycle (e.g., in the case of post-injection or pre-injection in diesel), and the main injection. These parameters can be considered as an injection profile to be applied to a potential upcoming ignition event. The advance time point when determining the injection parameters of the injection profile to be applied is typically referred to as the "fuel logic execution position".

[0003] There are problems that occur during the crank rotation phase. When the engine is driven by a starter (motor), the ECU needs to perform synchronization; this includes the ECU needing to determine the engine angular position and then start synchronization tasks (tasks executed at a defined angular position such as the fuel logic).

[0004] If synchronization is achieved a few degrees of crank after the fuel logic execution position (which can also be referred to as the fuel supply / injection curve determination position), then for the injection in a specific (upcoming) cylinder, this injection will not be programmed for that cylinder. As a result, the engine will require more time to start.

[0005] The object of the present invention is to overcome this problem. Summary of the Invention

[0006] In one aspect, there is provided a method for controlling fuel injection after engine startup, the method comprising performing the following steps:

[0007] a) At or after synchronization, determine or select a first injection curve for a potential upcoming ignition or injection event in a specific cylinder;

[0008] b) Determine whether there is sufficient time to implement the first injection curve;

[0009] c) If so, implement the first injection curve for the event.

[0010] The normal or standard time point for determining the injection curve for the upcoming event may have passed before synchronization.

[0011] In step b), if there is not enough time to implement the first injection curve, the method may not apply an injection curve with respect to the event.

[0012] Step b) may include determining whether the start of injection (SOI) of the first injection curve occurs at a time point (Tsoi1) before or after the synchronization time point (Tsynch).

[0013] In step b), if there is not enough time to implement the first injection curve, the following additional steps are performed:

[0014] d) Develop or select a second alternative injection curve;

[0015] e) Determine whether there is enough time to implement the second injection curve; if so, implement the second injection curve with respect to the event.

[0016] If there is not enough time to implement the second injection curve, an injection curve with respect to the event is not applied.

[0017] Step e) includes determining whether the start of injection (SOI) of the second injection curve occurs at a time point (Tsoi2) before or after the synchronization time point (Tsynch).

[0018] If there is not enough time to implement the second injection curve, one or more additional injection curves are selected with respect to the event. Description of the Drawings

[0019] The present invention will now be described by way of example with reference to the drawings, in which:

[0020] - Figure 1 Illustrates an example of the present invention. Detailed Description

[0021] The problem of delaying engine start (depending on where synchronization is obtained) is solved by performing a fuel determination event (i.e., an injection curve determination event) with respect to one or more injection curves at or just after synchronization, and then checking whether injection is still possible; i.e., whether there is enough time to implement the injection curve for an upcoming potential ignition / injection event.

[0022] This may occur after it has been determined that the standard or normal execution event time point has passed before synchronization.

[0023] Thus, during synchronization, for a particular potential upcoming cylinder injection / ignition event, the fuel injection quantity is determined and an injection curve is determined. The term "injection (pulse) curve" will be understood by the person skilled in the art and will be interpreted to include one or more injections in an injection cycle (e.g., one or more injections), their timing, the individual fuel quantities, etc. This can include determining the pulse curve for the fuel injector actuator.

[0024] If there is still sufficient remaining time to apply (i.e., implement) this first calculated injection curve (e.g., before the spark), then this injection curve will be used for the upcoming spark event; if not, it is determined that no injection will be made for the upcoming potential spark event, or it is determined whether at least one other (shorter) injection curve can be implemented, which has a shorter duration. If so, this shorter pulse curve will be used. As previously mentioned, if not, no injection will be applied for this ignition event. Thus, if possible, an injection curve that will fit the available time span is essentially selected.

[0025] Thus, in the example, the following steps will be taken. It should be noted that these steps do not necessarily occur in any particular order, and some steps can be provided by similar or alternative steps.

[0026] Step A

[0027] Here, for the first (standard) injection curve, the fuel determination event is performed at or just after synchronization, which occurs at a time: at least before the spark but typically at or shortly after synchronization.

[0028] Thus, at synchronization (or shortly after synchronization) for a particular (presumed / potential upcoming) combustion / ignition event regarding a particular cylinder, the first injection curve is determined and can include the following parameters: for example, the fuel injection quantity (injected by the fuel injector) for this cylinder, the timing for one or more injections to be made; that is, this can include one or more individual injections, as known in the art.

[0029] This can be considered that the fuel determination event provides (i.e., determines) the fuel supply (pulse) curve PP#1 (to be applied to the fuel injector actuator) for the upcoming potential ignition / combustion event.

[0030] Thus, in summary, at a later time point, engine synchronization, the fuel determination event are directly performed, and then parameters including one or more of fuel mass, main injection mode (segment duration and timing), and standby mode (delayed timing) are calculated for PP#1. If possible, this curve can be the standard or main curve to be applied.

[0031] Step B

[0032] This step is a comparison step. (After synchronization) it is determined (i.e., judged) whether it is possible to achieve the planned injection event of the determined curve PP#1 (in step A) for the cylinder for a putative / potential upcoming ignition / combustion event.

[0033] This can include determining the time span T1s between the synchronization time point Tsynch and the ignition time point Tspark for the upcoming potential ignition / combustion event e (or other nominal reference time point), and the time span T1pf between the injection start time point Tsoi1 of the determined curve (PP#1) and the ignition / spark time point Tspark (or other nominal time point). Or simply, whether the synchronization time point Tsynch is before the injection start (SOI) Tsoi1 of this injection curve PP#1.

[0034] Step C

[0035] If the latter (T1pf) of the injection curve PP#1 is shorter than the former (T1s), this step is achieved, i.e., if the synchronization time point (Tsynch) occurs before the SOI (T1soi) of this PP#1, then the fuel supply / pulse curve will be executed for the upcoming potential ignition / combustion event.

[0036] This is illustrated in Figure 1 Case 1 with similar reference numerals. So if the time point of Tsoi1 at synchronization has not passed, the fuel supply / pulse curve will be executed for the upcoming potential ignition / combustion event.

[0037] Step D

[0038] If (T1pf) of the injection curve PP#1 is not shorter than the former (T1s), i.e., if Tsynch is after Tsoi1 (SOI of PP#1), it is determined that there will be no injection for this upcoming spark event, or another fuel determination event will be achieved, where an alternative is determined, i.e., a different / shorter fuel supply curve (injector pulse curve), called the fuel supply / pulse curve PP#2.

[0039] In the latter case, the processing steps of step B are repeated for different pulse / fuel supply curves PP#2. Accordingly, the time span T2s between the synchronization time point Tsynch and the ignition time point Tspark (or other nominal time point) with respect to an upcoming potential ignition / combustion event is determined, as well as the time span T2pf between the injection start time point tsoi2 of the determined curve PP#2 and the ignition time point Tspark (or other nominal time point).

[0040] Or simply, whether Tsoi2 occurs after the synchronization time point Tsynch.

[0041] If (T2pf) is shorter than the former (T2s), in other words, if Tsynch occurs before the SOI (Tsoi2) of this injection curve PP#2, then the fuel supply / pulse curve PP#2 will be executed for the upcoming potential ignition / combustion event.

[0042] This is illustrated with similar reference numerals in Figure 1 case 2 of the drawings.

[0043] If not, i.e., if Tsynch occurs after Tsoi2, then another (e.g., even shorter) fuel supply pulse / curve will be selected and the appropriate steps repeated, or there will be no fuel injection for this upcoming potential ignition event (shown in Figure 1 case 3 of the drawings).

[0044] In some examples, the above steps may occur only after it is determined that the standard or normal execution event time point has passed before synchronization.

[0045] The present invention will now be explained with reference to Figure 1 This illustrates the method and shows the time lines for significant events in three cases with respect to different synchronization time lines for synchronization. Figure 1 The reference numeral 1 at T0 represents such a time point: for the spark / ignition event 2 at Tspark, the fuel (determination) event must typically (in the prior art) be determined before this time point. The reference numeral 3 represents the synchronization event, which occurs at Tsynch and occurs at different times T respectively in the three plotted graphs shown

[0046] in the three plotted graphs shown A T B T C .

[0047] In the following scenario, the nominal time point of fuel determination event 1 for a specific fuel injection and spark event in a cylinder during an engine cycle has occurred previously (i.e., before synchronization). Therefore, in the prior art, there would be no injection for the specific fuel injection and spark event in that cylinder during the engine cycle.

[0048] The following cases 1), 2), and 3) will be described with reference to Figure 1 case 1), case 2), and case 3) thereof.

[0049] To summarize briefly before this: Figure 1 The plot of shows events regarding the cylinder with respect to the crankshaft position (equivalent to time) on the x-axis in the figure. Reference numeral 1 represents the time at which the fuel determination event should typically be calculated at time T0, and reference numeral 3 represents the synchronization time. There is a planned spark / ignition / combustion event 2 at time Tspark near top dead center (TDC), and reference numeral 1 refers to the missed fuel determination event. The previous TDC (360 degrees before) at point T1 is non-ignition / spark as it is at the top of the exhaust stroke of a four-stroke engine.

[0050] Case 1

[0051] Figure 1 The plot a) of shows the events in case 1 in terms of crank angle (effectively a timeline). Here the synchronization time point Tsynch occurs at time T A at.

[0052] For the determined main standard injection curve PP#1, it will be applied with reference to the ignition point Tspark or typically TDC ignition as shown. The injection pattern / curve includes multiple main injections and multiple post-injections shortly after; this is generally represented by reference numeral PP#1. In the case of gasoline, there is usually no pre / main / post injection, but intake and compression injection.

[0053] Synchronization occurs at point T A before the time Tsoi1 which is the start of the injection pattern or curve of PP#1, i.e., before the injection start time point of the main (standard) injection pattern / scheme PP#1 (when applied to the injector of the cylinder for the injection event). Thus, this curve can then be applied to the injection of the cylinder; i.e., for this injection event, the standard injection pattern is applied to the injector.

[0054] In other words, when the pulse curve PP#1 is arranged for the corresponding spark time Tspark, here Tsych appears before Tsoi1 which is the start of the injection of the pulse curve PP#1.

[0055] T1s > t1pf, where (Tsynch - Tspark) = T1s, and (T1soi - Tspark) = T1pf.

[0056] Therefore, the method here continues with such programmed injections, which can be a standard injection pattern, or a pattern based on fixed criteria or a fixed protocol, depending on, for example, temperature, torque demand, etc.

[0057] Case 2

[0058] In this case, the synchronization time point Tsynch occurs at a time T after the injection start time point of the standard injection pattern scenario PP#1 (e.g., after point Tsoi1). B at.

[0059] Here, an additional alternative fuel supply pulse / pulse curve is selected / determined, e.g., a standby mode, called PP#2. For this, it is determined whether the injection start (called Tsoi2) of this standby mode PP#2 occurs after synchronization when applied to the ignition event. If so, this standby mode is implemented for the upcoming ignition event.

[0060] In other words, Tsoi2 is after Tsych, or

[0061] T2s > t2pf, where (Tsynch - Tspark) = T2s, and (T2soi - Tspark) = T2pf.

[0062] So, in case 2, if the injection start of the standby injection mode occurs after synchronization, the standby injection mode PP#2 is applied to the injector.

[0063] Case 3

[0064] In this case, the synchronization time point Tsynch occurs again at T C at, after the injection start time point of the standard injection pattern scenario (e.g., after point Tsoi1), and also after the injection start of the standby injection mode (e.g., after Tsoi2). Since it is too late to implement the standby injection mode, no injection occurs.

[0065] In other words, Tsoi2 is before Tsynch, or

[0066] T3s < t2pf, where (Tsynch - Tspark) = T2s, and (T2soi - Tspark) = T2pf.

[0067] This method allows for the correct management of the first fuel injection even when the synchronization point is after the normal fuel event position. Compared with the prior art, the advantage of the present invention is that the starting time is generally reduced by about 1 segment (even 2 segments for a 4-cylinder engine).

Claims

1. A method for controlling fuel injection after engine startup, the method comprising performing the following steps: a) At or after synchronization, determine or select a first injection curve with respect to a potential upcoming ignition or injection event for a particular cylinder; b) Determine whether there is sufficient time to implement the first injection curve; c) If so, implement the first injection curve with respect to the ignition or injection event; And wherein, in step b), if there is not sufficient time to implement the first injection curve, no injection curve is applied with respect to the ignition or injection event or the following additional steps are performed: d) Develop or select an alternative second injection curve; e) Determine whether there is sufficient time to implement the second injection curve; if so, implement the second injection curve with respect to the ignition or injection event.

2. The method according to claim 1, wherein, The nominal or standard time point for determining the injection curve for the ignition or injection event has passed before synchronization.

3. The method according to claim 1 or 2, wherein, Step b) includes determining whether the start of injection of the first injection curve occurs at a time point before or after the synchronization time point.

4. The method according to claim 1, wherein, If there is not sufficient time to implement the second injection curve, no injection curve is applied with respect to the ignition or injection event.

5. The method according to claim 1, wherein, Step e) includes determining whether the start of injection of the second injection curve occurs at a time point before or after the synchronization time point.

6. The method according to claim 1 or 5, wherein, If there is not sufficient time to implement the second injection curve, one or more additional injection curves are selected with respect to the ignition or injection event.

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