Method of resuming multi-port injection using an intake stroke and a vehicle using same

Abstract

A method of resuming multi-port injection using an intake stroke of an engine includes performing a first refueling with immediate start of ignition injection at the time when an injection abortion angle does not pass through an intake stroke, when injection is determined to be resumed after coasting by a controller. The method can minimize an engine RPM drop caused by the early generation of torque. The method improves fuel efficiency while being advantageous to calibration of the engine by setting the engine RPM to be low at the time of fuel cut-in.

Claims

1. A method of resuming MPI using an intake stroke, the method comprising: performing a first refueling with immediate SOI injection, when an injection abortion angle does not pass through an intake stroke, when injection is determined to be resumed after coasting by a controller, wherein the immediate SOI injection includes: determining whether the injection is resumed at the time of a fuel cut-in after a fuel cut-off during the coasting; applying the injection abortion angle to a cylinder when the injection is determined to be resumed; setting a cylinder through which the injection abortion angle does not pass as a determined cylinder; determining an injection EOI command angle of the determined cylinder, and performing the first refueling in the determined cylinder through which the injection EOI command angle passes.

2. The method of claim 1, wherein the injection abortion angle is applied after refueling is performed in each cylinder of an engine.

3. The method of claim 1, wherein the determined cylinder is a cylinder having the earliest compression TDC.

4. The method of claim 1, wherein the immediate SOI injection is changed to the EOI command angle injection after the first refueling is performed.

5. The method of claim 1, wherein, in the immediate SOI injection, the first refueling is performed with the EOI command angle injection when the injection EOI command angle does not pass through the determined cylinder.

6. The method of claim 5, wherein, in the EOI command angle injection, the refueling is performed in an exhaust stroke.

7. The method of claim 1, wherein, when a clutch pedal is operated to disengage an engine from a manual transmission in an engine idle state during the coasting, the performing of the refueling is changed to all cylinders from a partial cylinder by torque filtering.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flowchart illustrating a method of resuming MPI using an intake stroke according to an embodiment of the present disclosure.

(2) FIG. 2 is an example of a timing chart applied to the method of FIG. 1 of resuming MPI using an intake stroke according to an embodiment of the present disclosure.

(3) FIG. 3 is an example of a vehicle using the method of FIG. 1 of resuming MPI using an intake stroke according to an embodiment of the present disclosure.

(4) FIG. 4 is a diagram illustrating an intake injection state in which MPI is resumed in the intake stroke of a three-cylinder MPI engine according to an embodiment of the present disclosure.

(5) FIG. 5 is a pressure diagram for each cylinder of a three-cylinder MPI engine represented in FIG. 5 in which the intake injection is performed according to an embodiment of the present disclosure.

(6) FIG. 6 is a diagram illustrating the operation of a three-cylinder MPI engine represented in FIG. 5 in which the intake injection is performed according to an embodiment of the present disclosure.

DESCRIPTION OF SPECIFIC EMBODIMENTS

(7) Embodiments of the present disclosure are described below in more detail with reference to the accompanying drawings. The present disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and so that the written description will fully convey the scope of the present disclosure to those having ordinary skill in the art. Throughout the written description, like reference numerals refer to like parts throughout the various figures and embodiments of the present disclosure.

(8) Referring to FIG. 1, a method of resuming MPI using an intake stroke according to an embodiment of the present disclosure is described. The method is mainly characterized by using the earliest cylinder among cylinders to be injected through which the injection abortion angle of a camshaft does not pass. The earliest cylinder is detected at the time when fuel cut-in for injection resumption is determined to be resumed (S20) after a coasting condition. A first refueling is performed in the earliest cylinder with immediate SOI injection using an intake stroke.

(9) Therefore, the method of resuming MPI determines the earliest cylinder for intake injection among some cylinders rather than among all cylinders. The method reflects the determined cylinder to set a fuel cut pattern for partial resumption of injection. In particular, a vehicle equipped with an engine and a manual transmission may be operating under the condition in which the engine RPM is equal to or lower than a specific RPM in an engine idle state during coasting. Under this operating condition, when the engine is determined to be disengaged from the manual transmission by pressing a clutch pedal, refueling is changed to be performed in all cylinders rather than a partial cylinder even though the refueling is performed in the partial cylinder by torque filtering.

(10) Accordingly, the method of resuming MPI using an intake stroke is characterized by performing refueling from a cylinder having the earliest ignition TDC when fuel cut-in is determined to be resumed after fuel cut-off under a coasting condition.

(11) Referring to FIG. 2, the timing chart for controlling the resumption of MPI illustrates that a combustion cycle is classified into a suction stroke (or intake stroke), a compression stroke, an expansion stroke (or explosion stroke), and an exhaust stroke. The abortion angle after a lapse of time, at which fuel injection is calculated (calc) with respect to the ignition TDC cylinder at which refueling determination is calculated in the suction stroke (or intake stroke), is set as an IAA time. As a result, a first refueling is immediately performed through the section indicated by Ti in the suction stroke (or intake stroke) through which the abortion angle does not pass. This enables intake injection (i.e. immediate SOI injection) to be resumed instead of exhaust injection (i.e. EOI command angle injection).

(12) Hereinafter, the method of resuming MPI using an intake stroke will be described in detail with reference to FIGS. 3-6. Here, the control subject is a controller 10 connected to a timing chart map 10-1. The target to be controlled is an MPI system in which an MPI control method is applied to an engine 1-1 of a vehicle 1. In one embodiment, the vehicle 1 may be a hybrid vehicle. Although the engine 1-1 has any number of cylinders, a three-cylinder engine is applied for convenience of description. In addition, the controller 10 may be an engine ECU or an HCU.

(13) S10 is a step of entering fuel cut-off under the coasting condition of the engine 1-1 by the controller 10. Here, coasting means a state in which the engine 1-1 is maintained at a constant speed to reduce fuel in such a manner that a driver does not press an accelerator pedal while the vehicle 1 is driven on a downhill road.

(14) S20 is a step of determining whether injection is resumed at the time of fuel cut-in after fuel cut-off by the controller 10. In this case, the controller 10 applies SOI to the injection resumption determination.

(15) S30 is a step of determining a cylinder having the earliest compression TDC, through which an abortion angle does not pass, at the time when the injection is determined to be resumed by the controller 10. S40 is a step of determining whether an injection EOI command angle of the determined cylinder having the earliest compression TDC passes by the controller 10. In this case, since the abortion angle is a value set based on a fuel injection angle, the case where the abortion angle passes means the passing of the abortion angle, and the abortion angle is applied after the fuel injection angle for each cylinder of the engine. Therefore, the controller 10 performs immediate SOI injection when the injection EOI command angle passes, whereas the controller 10 performs EOI command angle injection when the injection EOI command angle does not pass.

(16) S50 is a step of performing refueling with immediate SOI injection by the controller 10. In this case, the immediate SOI injection is a method of performing refueling based on the fuel injection angle calculated in an intake stroke. Therefore, in the immediate SOI injection, fuel is injected into the cylinder through which the injection EOI command angle passes while having the earliest compression TDC through which the abortion angle does not pass.

(17) On the other hand, S60 is a step of performing refueling with EOI command angle injection by the controller 10. In this case, the EOI command angle injection is a method of typically performing refueling according to the set injection EOI command angle, and is based on the fuel injection angle calculated in an exhaust stroke.

(18) FIGS. 4 and 5 illustrate an example of immediate SOI injection.

(19) Referring to FIG. 4, a cylinder order can be seen in which refueling is performed through immediate SOI injection in the engine 1-1 having first, second, and third cylinders CYL 1, CYL 2, and CYL 3. By way of example, the cylinders within the range of IAA at the time of fuel cut-in are CYL 1, CYL 2, and CYL 3. Therefore, when the combustion cylinders are CYL 1, CYL 2, and CYL 3, the intake injection is performed in which first refueling is performed in the order of CYL 2.fwdarw.CYL 3.fwdarw.CYL 1. Here, the arrow symbol .fwdarw. refers to a progress direction.

(20) Referring to the pressure diagram for each cylinder of the engine 1-1 in FIG. 5 and the operation diagram of the engine 1-1 in FIG. 6, it can be seen that, since the intake injection is performed in the order of CYL 2.fwdarw.CYL 3.fwdarw.CYL 1, an engine torque is early generated and thus an engine RPM drop is minimized.

(21) As such, the immediate SOI injection is performed by detecting the cylinder having the earliest TDC at the time when the injection is determined to be resumed at the time of fuel cut-in after coasting. In this case, when the engine is determined to be disengaged from the manual transmission by pressing the clutch pedal under the condition in which the RPM of the engine is equal to or lower than a specific RPM in the engine idle state while the manual transmission vehicle coasts, the refueling may be performed in all cylinders even though the refueling is performed in a partial cylinder by torque filtering.

(22) Meanwhile, referring to FIG. 2, when MPI control begins by the resumption of fuel cut-in after coasting, the controller 10 performs first refueling through immediate SOI injection in the suction stroke (or intake stroke) through which the abortion angle does not pass, and then performs second refueling and subsequent refueling based on the injection EOI command angle. In this case, the EOI command angle injection shows that refueling is performed in the section indicated by T in the exhaust stroke. Therefore, the above MPI control method may be defined as an intake/exhaust mixing refueling method.

(23) As described above, the method of resuming MPI using an intake stroke according to the embodiment of the present disclosure performs the first refueling through immediate SOI injection at the time when the injection abortion angle does not pass through the intake stroke, when fuel cut-in is determined to be resumed after fuel cut-off under the coasting condition by the controller. Accordingly, it is possible to minimize an engine RPM drop caused by the early generation of torque, and particularly to improve fuel efficiency while being advantageous to calibration by setting the engine RPM to be low at the time of fuel cut-in.

(24) The method of resuming MPI according to the present disclosure has a number of advantages and effects achieved by an intake/exhaust mixing refueling method in which first refueling is performed with immediate SOI injection using an intake stroke and is then performed according to an EOI command angle.

(25) First, a new method of performing refueling at the time of fuel cut-in can be obtained using the abortion angle of a camshaft. Second, since fuel is immediately injected into the earliest cylinder among cylinders to be injected through which the abortion angle of the camshaft does not pass, an engine torque can be early generated by performing the first refueling with the immediate SOI injection. Third, an engine RPM can be set to be low at the time of fuel cut-in so as to be advantageous to calibration by minimizing an engine RPM drop caused by the early occurrence of torque. Fourth, since the fuel cut-in is controlled to be resumed at a lower engine RPM, it is possible to improve fuel efficiency. Fifth, the engine torque can be generated prior to 1-2 segments, compared to an exhaust stroke method, by performing refueling with intake injection when the injection is resumed after a coasting condition, and it is thus possible to minimize the RPM drop in an idle state and reduce the risk of engine stall.

(26) While the present disclosure has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the disclosure as defined in the following claims.