Method for fuel quantity distribution for an engine with dual injector

Abstract

A fuel quantity distribution method for distributing fuel to a plurality of injectors (20) provided on each of a plurality of cylinders of an engine having a dual injector, the method comprising: Determining by a controller whether a required fuel injection time of the dual injector of the at least one cylinder of the plurality of cylinders is shorter than a minimum injection time of each injector (20) of the plurality of injectors of the dual injector, Performing a single injection operation by the controller, in which a single injector (20) from the plurality of injectors (20) forming the dual injector injects fuel into a corresponding cylinder when the required injection time of the dual injector of at least one cylinder of the plurality of cylinders is shorter than the minimum injection time of each injector (20) from the plurality of injectors of the dual injector, and Compensating, by the controller, the set fuel injection timing using a predetermined compensation map when a fuel injector operation is switched from a dual injection operation of the fuel injection in which the plurality of injectors of the dual injector inject fuel to the single injector operation using the single injector, or when the fuel injection operation is switched from the single injection operation to the dual injection operation in which the individual injectors constituting the dual injector periodically alternately perform the single injection operation.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a method for fuel quantity distribution for an engine with a dual injector. TECHNICAL BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and do not (necessarily) represent prior art.

[0003] Generally, a conventional engine is designed with only one injector for each intake port. Specifically, an MPI (Multi-Point Injection) engine is an engine that has a fuel injector installed in each cylinder and operates by pre-injecting fuel into each intake manifold. The MPI engine uses a system that provides two intake valves and two exhaust valves for each cylinder, and uses a single injector for the two intake valves.

[0004] In contrast, an engine with a dual-port injector is configured so that two injectors inject fuel into the same cylinder. The two intake ports may communicate with the interior of the same cylinder, and two injectors may be arranged behind intake valves that are provided for opening or closing the respective intake ports. Using a dual-port injector provides advantages in that fuel efficiency can be improved by increasing volumetric efficiency, and the amount of pollutants in the exhaust gas can be reduced.

[0005] Meanwhile, an injector has a minimum injection time, and the fuel injection time of the injector cannot be controlled to a value less than the minimum injection time. In the case of a light-load driving condition, especially in the case of a high-temperature idling driving condition or a high-concentration scavenging condition, a required fuel injection amount is small, so the fuel injection time must be controlled to be short. However, we found that if the minimum injection time of the dual injector is not sufficiently short, the required injection time may be shorter than the minimum injection time. In this case, there is a problem in that the fuel injection amount cannot be controlled with a very small fuel amount.

[0006] In the conventional technique, an air-fuel ratio control operation is disabled, and the fuel injection timing is fixed at the controllable minimum injection timing of the dual injector. As a result, the amount of injected fuel becomes larger than the required fuel injection amount. For example, if the minimum injection timing of the injector is 1.0 ms, and the fuel injection amount distribution coefficients of two injectors in each cylinder are the same, and a required injection time of each injector is 0.7 ms, in the conventional technique, each injector injects fuel for a fuel injection time 1.0 ms longer than the required injection time. As a result, it is difficult to precisely control the air-fuel ratio.

[0007] US 2014 / 0 007 843 A1 describes a prior art fuel injection control device. DE 102010 064 184 A1 and DE 10 2011 007 367 A1 are further prior art. DEPICTION

[0008] In one embodiment, the present disclosure is directed to a fuel amount distribution method for an engine having a dual injector, which can provide excellent injection control performance even in a low fuel rate section.

[0009] The invention is defined by claim 1 and aims to achieve the advantages described in the preceding paragraph. Advantageous further developments are defined in the dependent claims.

[0010] Other objects and advantages of the present disclosure will be understood from the following description and will become apparent with reference to the embodiments of the present disclosure.

[0011] According to one embodiment of the present disclosure, a fuel quantity distribution method for distributing fuel to a plurality of injectors provided on each of a plurality of cylinders of an engine with a dual injector is provided. In particular, the method includes performing, by a controller, a single injection operation in which a single injector of the plurality of injectors forming a dual injector injects fuel into a corresponding cylinder when a required injection time of the dual injector of at least one cylinder of the plurality of cylinders is shorter than a minimum injection time of each injector of the plurality of injectors of the dual injector.

[0012] The method may further include a step of setting the minimum injection time of each injector as the fuel injection time when it is determined that a total required injection time obtained by adding the injection times of each injector of the corresponding cylinder is equal to or shorter than the minimum injection time of each of the injectors constituting the dual injector.

[0013] In another embodiment, the method may further include a step of setting the required injection time as the fuel injection time when it is determined that a total required injection time obtained by adding the injection times of each injector of the corresponding cylinder exceeds the minimum injection time of each of the injectors constituting the dual injector.

[0014] After a fuel injection operation is switched to a single injection operation using a single injector, the method may further perform a step of switching the single injection operation to a dual injection operation in which the plurality of injectors of the dual injector inject fuel into the corresponding cylinder when it is determined that the required fuel injection time of the dual injector of the corresponding cylinder satisfies the minimum injection time of each of the injectors constituting the dual injector.

[0015] In another embodiment, when the fuel injection operation is switched from a dual injection operation of the fuel injection from the plurality of injectors to the single injection operation using a single injector, the set fuel injection timing is compensated using a predetermined compensation map.

[0016] In yet another embodiment, when the fuel injection operation is switched from the single injection operation using the single injector to the dual injection operation, a fuel injection timing in the dual injection operation is compensated using a predetermined compensation map.

[0017] In another embodiment, when the fuel injection operation is switched from the single injection operation using the single injector to the dual injection operation, a predetermined option value (hysteresis) may be applied to the required injection time of the dual injector of the corresponding cylinder, which serves as a reference value.

[0018] The individual injectors that form the dual injector can perform single injection operation alternately on a regular basis.

[0019] The individual injectors can perform single injection operation alternately on a regular basis whenever a vehicle travels a given distance.

[0020] Further areas of applicability will become apparent from the description provided herein. It is to be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS

[0021] In order that the disclosure may be clearly understood, various embodiments thereof will now be described by way of example, with reference to the accompanying drawings in which: Fig. 1 is a view illustrating an intake passage portion of an engine with a dual injector to which the present disclosure is applied; and Fig. 2 is a flowchart illustrating a fuel quantity distribution method for a dual injector engine.

[0022] The drawings described herein are for illustrative purposes only and do not limit the scope of the present disclosure in any way. DETAILED DESCRIPTION

[0023] The following description is merely exemplary in nature and is not intended to limit the disclosure, application, or use. It should be noted that corresponding reference characters in the drawings indicate similar or corresponding parts and features.

[0024] However, the present disclosure may be embodied in various embodiments and should not be construed as limited to the embodiments set forth herein. In certain embodiments, information irrelevant to the present disclosure may be omitted to avoid obscuring the understanding of the disclosure.

[0025] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0026] Fig. 1 is a view illustrating an intake passage portion of a dual-port injector engine to which a control method of the present disclosure is applied. Referring to Fig. 1, each cylinder of an engine is provided with two intake ports 30 that communicate with a corresponding combustion chamber. Each of the intake ports 30 is provided with an intake valve 20 that opens or closes the intake port 30. Furthermore, a plurality of injectors 10 are provided, each of which is arranged downstream of the corresponding intake valve 20.

[0027] In the dual-port injector with the above-mentioned configuration, the plurality of injectors inject fuel into the same cylinder through their respective intake ports. The fuel injected through the intake ports mixes with air and is then supplied as a gas mixture into the combustion chamber.

[0028] The embodiment of the present disclosure is not limited to the Fig. 1 and can be applied to any dual-injector engine provided the engine includes a plurality of injectors.

[0029] Fig. 2 is a flowchart illustrating a fuel quantity distribution method for a dual injector engine in one embodiment of the present disclosure. In Fig. 2 illustrates a fuel quantity distribution method by which, if a required injection time in any cylinder of the dual injector engine is shorter than the minimum injection time of each of the individual injectors constituting the dual injector 10, the amount of fuel injected from each of the injectors is controlled to precisely control an air-fuel ratio.

[0030] In one embodiment, the control method may be used when the vehicle is in a low fuel rate driving state (e.g., in a light load driving mode), that is, when the driving vehicle is about to enter an idle driving state, or when the stopped vehicle is in a high-temperature idle driving state or in a high-concentration scavenging state (at step S100). Because a fuel injection rate is reduced in the light load driving state, the required fuel injection time of the dual injector 10 may be shorter than the minimum injection time, which is a preset specification of the dual injector. In this case, since the fuel injection time of the injector cannot be controlled to be less than the minimum injection time, the amount of fuel injected by the dual injector 10 exceeds a required fuel injection amount.As a result, a desired fuel / air control operation cannot be carried out properly.

[0031] Therefore, in the present disclosure, a controller such as an ECU (Electronic Control Unit) provided in the vehicle determines whether the required fuel injection time by injectors in any cylinder of the engine including a plurality of cylinders is shorter than the minimum injection time of each of the individual injectors constituting the dual injector 10 (at step S110). For example, if the minimum injection time of each of the individual injectors constituting the dual injector 10 is 1.0 ms and the fuel amount distribution coefficients between the two injectors are the same, and if the fuel injection time required by the dual injector 10 is 0.7 ms, the required fuel injection time of the dual injector 10 is shorter than the minimum injection time of each injector. In this case, according to the conventional technique, fuel is injected by each individual injector for an injection time of 1.0 ms.As a result, fuel is injected for 2.0 ms, which exceeds 1.4 ms (0.7 ms + 0.7 ms), which is a target value for the total required injection time of the cylinder in question.

[0032] With this in mind, in the present disclosure, the ECU controls the dual injector 10 such that only one injector among the plurality of injectors constituting the dual injector 10 injects fuel for the required fuel injection time. In the case of the foregoing example, unlike the conventional technique in which each of the two injectors injects fuel for 1.0 ms (the total fuel injection time: 2.0 ms), the present disclosure operates such that one injector injects fuel for 1.4 ms. Therefore, in a low fuel rate section, fuel can also be injected for the required fuel injection time, making it possible to precisely control the air-fuel ratio.

[0033] In another embodiment, it is determined whether the total required injection time (corresponding to the target fuel injection amount) obtained by adding the injection times of the respective individual injectors for the cylinder in question is the minimum injection time of each injector or shorter than it (at step S120). For example, if the fuel injection time required by the dual injector 10 is 0.4 ms and a preset minimum injection time of each individual injector is 1.0 ms, the total required injection time of the cylinder in question obtained by adding the required injection times of the respective injectors is 0.8 ms and is thus shorter than 1.0 ms, which is the minimum injection time of each injector.

[0034] Given that it is impossible to inject fuel for a time shorter than the preset minimum injection time, the ECU sets the preset minimum injection time (in this example, 1.0 ms) of each injector as a target fuel injection time and controls the dual injector 10 so that only one injector injects fuel for the corresponding injection time (in step S130). In this case, although the actual fuel injection time exceeds the target required fuel injection time, a difference between them can be remarkably reduced compared to that of the conventional technique.

[0035] On the other hand, if the total required injection time obtained by summing the injection times of the respective individual injectors for the respective cylinder exceeds the minimum injection time of each of the injectors constituting the dual injector 10, the ECU controls the dual injector 10 such that the target required injection time is set as the fuel injection time, and (in step 140) only one injector injects fuel for a corresponding injection time. With regard to the previous example, if the fuel injection time required by the dual injector 10 is 0.6 ms, the total required injection time of the respective cylinder is 1.2 ms, obtained by summing the required injection times of the respective individual injectors, and thus exceeds 1.0 ms, which is the minimum injection time of each injector.Therefore, in this case, the total required fuel injection time (1.2 ms in this example) is set as the fuel injection time, in other words, the target fuel injection time, and then the dual injector 10 is controlled so that only one injector injects fuel for the corresponding injection time (in step S140). This allows fuel to be injected by the injector at the original required target fuel amount, making it possible to precisely control the air-fuel ratio.

[0036] Meanwhile, after the injection mode of the dual injector is switched to a single injection mode using the single injector in the previous step, the ECU determines whether the required injection time of each injector of the cylinder in question has satisfied the minimum injection time of each of the injectors constituting the dual injector to determine a timing for resetting the injection mode to a dual injection mode (at step S150). If the required injection time of the dual injector 10 of the cylinder in question is the minimum injection time or more of each of the injectors constituting the dual injector, the injection mode is switched to the dual injection mode in which the plurality of injectors inject fuel (at step S160).When the vehicle is outside the low fuel rate range and the required target injection time thus exceeds the minimum injection time of each injector, it is no longer necessary to maintain the single injection mode using a single injector. Therefore, as usual, the injection mode is switched to the dual injection mode, which uses multiple injectors to inject fuel.

[0037] Meanwhile, in the case of high-temperature idle conditions and high-concentration purge conditions while the vehicle is stationary, if the injection mode regularly switches between the single-injection mode and the dual-injection mode, since the required target injection time regularly reaches the minimum injection time under light load conditions, this may affect the air-fuel ratio control and combustion stability in transient regions. Accordingly, when the injection mode is switched to the single-injection mode, the injection mode may be pre-switched when or before the required fuel injection time reaches the minimum injection time of each injector.Furthermore, when the injection mode returns from the single injection mode to the dual injection mode, hysteresis may be present, so that the injection mode is inhibited or prevented from regularly switching between the single injection mode and the dual injection mode. In one embodiment, a predetermined option value may be applied to the required fuel injection time of the dual injector, which is a reference condition for switching the injection mode back to the dual injection mode, so that the timing at which the injection mode is switched from the single injection mode to the dual injection mode can be delayed.

[0038] In the case where the vehicle is kept in a light-load or low-fuel-rate state for a long time, if only one injector continuously performs single-injection operation, the creep performance of that injector may be adversely affected. Therefore, in the single-injection mode, the injector used for one injection may be periodically changed among the plurality of injectors. For example, the injector performing single-injection operation may be replaced with another injector when a vehicle travels a predetermined distance or more, or when a predetermined time has elapsed.

[0039] In an injection system using a PFI (port fuel injection)-based dual injector, when the injection mode is switched from the dual injection mode to the single injection mode under the above-mentioned conditions, the fuel injection amount may be smaller than that in the normal dual injection mode under the same fuel amount condition, depending on both the compensation of a dead time until the injector opens caused by a battery voltage change and the actual injection position of the injector in the intake port. To compensate for this, in the single injection mode, a compensation map generated based on the engine RPM (revolutions per minute) and load conditions may be used to compensate for an injection timing in the single injection mode.

[0040] Furthermore, when the injection mode is switched to the dual injection mode after the injection operation is performed in the single injection mode, when fuel (more precisely, a fuel wall film) is removed from the wall of a portion of the intake passage where an injector that was not used for injection is located, a fuel shortage phenomenon may be caused temporarily when the injector in question re-injects fuel upon returning to the dual injection mode. Therefore, when the injection mode returns from the single injection mode to the dual injection mode, the fuel injection timing may be compensated based on the compensation map to compensate for the fuel shortage phenomenon.

[0041] In a typical PWM (Pulse-Width Modulation) method used as a method for controlling a PFI injector, it is difficult to meet the required specifications of a dual injector capable of precisely controlling an air-fuel ratio of a low fuel rate region while simultaneously satisfying high-temperature idling and high-concentration scavenging conditions. If a control method according to the present disclosure is employed, even when a dual injector with a comparatively long minimum injection time is used, it is possible to precisely control the air-fuel ratio of the low fuel rate region.

[0042] According to the present disclosure, it is not necessary to change the configuration of a controller; for example, installing an additional chipset for controlling the air-fuel ratio of the low fuel rate region is not necessary. The present disclosure only uses a technique for determining the minimum injection time in a dual injection mode and a technique for controlling switching between the dual injection mode and a single injection mode, thus making it possible to precisely control the air-fuel ratio of the low fuel rate region. This provides an advantage in that production costs can be reduced.

Claims

[1] A fuel quantity distribution method for distributing fuel to a plurality of injectors (20) provided on each of a plurality of cylinders of an engine having a dual injector, the method comprising: Determining by a controller whether a required fuel injection time of the dual injector of the at least one cylinder of the plurality of cylinders is shorter than a minimum injection time of each injector (20) of the plurality of injectors of the dual injector, Carrying out a single injection operation by the controller, in which a single injector (20) from the plurality of injectors (20) forming the dual injector injects fuel into a corresponding cylinder when the required injection time of the dual injector of at least one cylinder of the plurality of cylinders is shorter than the minimum injection time of each injector (20) from the plurality of injectors of the dual injector, and Compensating, by the controller, the set fuel injection timing using a predetermined compensation map when a fuel injector operation is switched from a dual injection operation of the fuel injection in which the plurality of injectors of the dual injector inject fuel to the single injector operation using the single injector, or when the fuel injection operation is switched from the single injection operation to the dual injection operation in which the individual injectors constituting the dual injector periodically alternately perform the single injection operation. [2] A fuel quantity distribution method according to claim 1, further comprising: Setting the minimum injection time of each of the injectors (20) as a fuel injection time when it is determined that a total required injection time obtained by adding the injection times of each injector (20) of the corresponding cylinder is equal to or shorter than the minimum injection time of each of the injectors (20) constituting the dual injector. [3] A fuel quantity distribution method according to claim 2, further comprising: Compensating the set fuel injection timing using a preset compensation map when an operation of a fuel injector is switched from a dual injection operation of the fuel injection of the plurality of injectors (20) to the single injector operation using the single injector. [4] A fuel quantity distribution method according to claim 1, further comprising: Setting the required fuel injection time as the fuel injection time when it is determined that a total required injection time obtained by adding the injection times of each injector (20) of the corresponding cylinder exceeds the minimum injection time of each of the injectors (20) constituting the dual injector. [5] A fuel quantity distribution method according to claim 1, further comprising: after a fuel injection operation is switched to a single injection operation using the single injector, switching the single injection operation to a dual injection operation in which the plurality of injectors of the dual injector inject fuel into the corresponding cylinder when it is determined that the required fuel injection time of the dual injector of the corresponding cylinder satisfies the minimum injection time of each of the injectors (20) constituting the dual injector. [6] A fuel quantity distribution method according to claim 1, further comprising: Applying a predetermined option value to the required injection time of the dual injector of the corresponding cylinder when the fuel injection mode is switched from the single injection mode using the single injector to the dual injection mode. [7] Method for fuel quantity distribution according to one of the preceding claims, wherein the individual injectors forming the dual injector carry out the single injection operation alternately. [8] A method for distributing fuel quantity according to claim 7, wherein the individual injectors alternately carry out the single injection operation whenever a vehicle travels a predetermined distance.

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