JP5375800B2 - Heating control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating control device for an internal combustion engine capable of securing a stable combustion after starting while ensuring its durability through reduction of the electric load to a heating means. <P>SOLUTION: The heating control device of the internal combustion engine 1 having a plurality of glow plugs 4A-4D respectively installed at cylinders 1A-1D and emitting heat when current is fed, is structured so that the cylinders can be heated by the glow plugs 4A-4D before and after starting of the engine. The heating control device comprises combusting condition sensing means 15A-15D to sense the combusting condition of the cylinders, a heating control means 20 to control the heating amounts of the respective cylinders by the glow plugs 4A-4D on the basis of the combusting conditions of the cylinders sensed by the sensing means, and an output correcting means 30 to correct the output variation of the engine caused by the control of the glow plugs. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a heating control device for an internal combustion engine, and more particularly to a control technology for afterglow after starting.

  2. Description of the Related Art A diesel engine that is an internal combustion engine that injects high-pressure fuel into a cylinder from a fuel injection valve includes a glow plug serving as a heating means in the combustion chamber of each cylinder. In addition, preheating is performed by energizing the glow plug before starting, and afterglow is performed to energize the glow plug after starting, thereby ensuring startability and combustion stability immediately after starting. However, a shorter energization time to the glow plug is preferable if unnecessary because of an increase in electrical load and durability.

  Patent Document 1 discloses a configuration in which the exhaust temperature of a cylinder is detected, and when the exhaust temperature after the end of afterglow is reduced to a predetermined temperature or less, the glow plug is re-energized to resume afterglow. .

Japanese Patent Laid-Open No. 58-200080

In a diesel engine, the warm-up process after startup differs depending on variations in the fuel injection amount, friction, compression ratio, and the like for each cylinder. Therefore, afterglow for cylinders with fast warm-up will continue to apply a wasteful electrical load to the glow plug. On the other hand, for cylinders with slow warm-up, combustion will occur when the power to the glow plug is turned off quickly. Becomes unstable, leading to an increase in unburned hydrocarbon emissions and misfires. In addition, it is preferable to turn off the power after judging the energization time and warm-up completion of the glow plug after starting, but it is not possible to judge the warm-up state of each cylinder from the cooling water temperature generally used. difficult. In that respect, since the exhaust temperature after starting each cylinder is detected in Patent Document 1 and afterglow is resumed when the exhaust temperature is low, energization control of the glow plug can be performed according to the operating state of the cylinder. As long as the operation state of the cylinder is stabilized by energizing the glow plug, the energization time is not reduced, which is disadvantageous in terms of durability of the glow plug.
An object of the present invention is to provide a heating control device for an internal combustion engine that can secure stable combustion after start-up while reducing the electrical load on the heating means and achieving durability.

  The internal combustion engine heating control apparatus according to the present invention is arranged in each cylinder of the internal combustion engine, and can heat each cylinder before and after the start of the internal combustion engine by heating means that generates heat when energized. A combustion state detection means for detecting the combustion state of the cylinder, a heating control means for controlling the amount of heating by the heating means of each cylinder based on the combustion state of each cylinder detected by the combustion state detection means, and a control to the heating means It has an output correction means for correcting output fluctuation of the fluctuating internal combustion engine.

  In the heating control apparatus for an internal combustion engine according to the present invention, there is provided a fuel injection valve that is disposed in each cylinder and injects fuel into each cylinder, and the output correction means is a cylinder of the cylinder detected by the combustion state detection means. The fuel injection valve is controlled so as to increase the fuel injection amount from the fuel injection valve for cylinders other than the cylinder whose combustion state exceeds a predetermined value and the energization to the heating means is stopped.

  In the heating control apparatus for an internal combustion engine according to the present invention, there is provided a fuel injection valve that is disposed in each cylinder and injects fuel into each cylinder, and the output correction means is a cylinder of the cylinder detected by the combustion state detection means. The fuel injection valve is controlled such that the fuel injection timing from the fuel injection valve for the cylinder whose combustion state exceeds a predetermined value and the energization to the heating means is stopped is corrected.

  In the heating control apparatus for an internal combustion engine according to the present invention, the combustion state detecting means is a temperature detecting means for detecting the temperature of the exhaust gas discharged from each cylinder, and the heating control means is for the cylinder detected by the temperature detecting means. When the exhaust temperature exceeds a predetermined value, the energization to the heating means is stopped, and when the exhaust temperature of the cylinder does not exceed the predetermined value, the energization to the heating means is continued and the heating amount by the heating means is reduced. It is characterized by control.

According to the present invention, when performing heating control to continue energization to the heating means for stable combustion after start-up, the heating means is energized for each cylinder according to the combustion state of each cylinder detected by the combustion state detection means. Thus, stable combustion after start-up can be ensured while reducing the electric load. Further, since the output fluctuation of the internal combustion engine that fluctuates due to the control to the heating means is corrected by the output correction means, even when the energization is stopped after the start of the heating means and the output fluctuation occurs in the internal combustion engine, Since it is possible to suppress output fluctuations instead of control, it is possible to ensure stable combustion after start-up while further reducing the electrical load on the heating means and achieving durability.
According to the present invention, the combustion state of the cylinder detected by the combustion state detection unit exceeds a predetermined value, and the fuel injection amount from the fuel injection valve is increased for cylinders other than the cylinder in which the energization to the heating unit is stopped. Since the fuel injection valve is controlled at the same time, even if the output of the cylinder that has stopped energizing the heating means is lower than when the heating means is energized, another cylinder that is energized to the heating means, i.e., unwarmed The amount of heat generated in the cylinder of the machine increases and the reduced output can be compensated not by the energization control by the heating means but by the increase in the fuel injection amount. It is possible to ensure stable combustion after start-up while reducing the target load and improving durability.
According to the present invention, the fuel is detected so that the combustion state of the cylinder detected by the combustion state detection means exceeds a predetermined value and the fuel injection timing from the fuel injection valve for the cylinder whose energization to the heating means is stopped is advanced. Since the injection valve is controlled, even if the cylinder that has stopped energizing the heating means is delayed in arrival and combustion is delayed compared to when the energization is applied to the heating means, the fuel is not controlled by the heating means. Since combustion can be stabilized by correcting the advance angle of the injection timing, it is possible to ensure stable combustion after start-up while further reducing the electrical load on the heating means and achieving durability.

1 is a schematic configuration diagram of a heating control device for an internal combustion engine mounted on a vehicle according to the present invention. It is a flowchart which shows 1st Embodiment by the heating control apparatus shown in FIG. It is a flowchart which shows 2nd Embodiment by the heating control apparatus shown in FIG.

Hereinafter, heating control of an internal combustion engine according to the present invention will be described with reference to the drawings.
In FIG. 1, the internal combustion engine is assumed to be a four-cylinder in-line diesel engine 1 (hereinafter simply referred to as “engine 1”) which is an in-cylinder injection spontaneous ignition engine. The number of cylinders is not limited to four, but may be V-type instead of in-line.

  In FIG. 1, the fuel supply system of the engine 1 is constituted by, for example, a common rail system. In the common rail system, injectors 3 </ b> A to 3 </ b> D serving as electromagnetic open / close fuel injection valves are provided in the cylinders denoted by reference numerals 1 </ b> A to 1 </ b> D. These injectors 3A to 3D are respectively connected to a common rail 5 that holds the fuel stably at a high pressure via a fuel injection pipe. Such a common rail system is publicly known, and detailed description of the configuration of the common rail system is omitted here.

  Injectors 3A to 3D are connected to ECU 20 serving as control means, and open and close the solenoid valve at a high speed based on a fuel injection command from ECU 20, and burn high pressure fuel in common rail 4 to each cylinder at a desired timing. It is comprised so that injection to a chamber is possible. In this embodiment, the injectors 3 </ b> A to 3 </ b> D pre-supply main fuel for main combustion, and supply a smaller amount of fuel into the combustion chamber before the main injection in order to promote combustion and the like. The fuel injection is performed after the injection and the main injection so that the well-known multi-stage injection of the after injection for improving the trade-off between NOx and soot can be performed.

  Glow plugs 4A to 4D serving as glow plugs 4A to 4D as heating means that generate heat when energized are arranged above the cylinders 1A to 1D. These glow plugs 4 </ b> A to 4 </ b> D are configured to be able to heat each cylinder when energized before and after the engine 1 is started.

  The engine 1 is equipped with a turbocharger 12. An intake pipe 8 is connected via an intake manifold 6 to an intake port connected to the combustion chamber of the engine 1 and opened and closed by an intake valve. A compressor of a turbocharger 12 is connected to the intake pipe 8. An intercooler 7 and a throttle valve 9 for cooling the intake air are arranged in an intake pipe 8 between the intake manifold 6 and the compressor.

  An exhaust pipe 11 is connected via an exhaust manifold 10 to an exhaust port connected to the combustion chamber and opened and closed by an exhaust valve. A turbine of the turbocharger 12, an exhaust aftertreatment device, a silencer, and the like are interposed in the exhaust pipe 12, but description thereof is omitted here. The exhaust manifold 10 and the intake pipe 8 are connected by a known exhaust gas recirculation passage 13 for exhaust gas recirculation. The exhaust gas recirculation passage 13 is provided with an electromagnetic exhaust gas recirculation valve 14 for adjusting the exhaust gas recirculation amount. The exhaust gas recirculation valve 14 is configured to control the exhaust gas recirculation amount by controlling the opening and closing of the ECU 20 according to the operating state of the engine 1. The exhaust manifold 10 is provided with exhaust temperature sensors 15A to 15D serving as temperature detection means for detecting the temperature of exhaust discharged from the cylinders 1A to 1D. These exhaust temperature sensors 15A to 15D function as combustion state detection means for detecting the combustion states of the cylinders 1A to 1D.

  The ECU 20 is a control means for performing overall control of the engine 1 and is configured by a computer. In the present embodiment, the ECU 20 also functions as a heating control means. On the input side of the ECU 20, together with various sensors, exhaust temperature sensors 15 </ b> A to 15 </ b> D that detect the exhaust temperature Ht, a crank angle sensor 21 that serves as a rotation detection unit that detects engine rotation information Ne, and engine load information θ are detected. An accelerator opening sensor 22 serving as load detecting means is connected. The injectors 3 </ b> A to 3 </ b> D and the glow plugs 4 </ b> A to 4 </ b> D are connected to the output side of the ECU 20 along with various devices and the exhaust gas recirculation valve 14.

  In the ROM (not shown) of the ECU 20, the injection timing of pre-injection, main injection, and after-injection, and the injection period (injection amount) at each injection are set according to the engine operating state obtained from the engine rotation information Ne and the load information θ. Has been.

In the ROM (not shown) of the ECU 20, a predetermined time T1 for determining the energization time T to the glow plugs 4A to 4D and a predetermined temperature Ht1 that is a predetermined value for determining the combustion state of each cylinder are set. In the ROM (not shown) of the ECU 20, the heating time T by the glow plugs 4A to 4D has passed a predetermined time T1, and the exhaust temperature Ht of each cylinder detected by the exhaust temperature sensors 15A to 15D is equal to the predetermined temperature Ht1. When it exceeds, the energization to the glow plugs 4A to 4D is stopped, and when the exhaust temperature Ht does not exceed the predetermined temperature Ht1, the energization to the glow plugs 4A to 4D is continued and the glow plugs 4A to 4D are used. A routine for controlling the heating amount is stored. That is, the ECU 20 controls the amount of heating by the glow plugs 4A to 4D of each cylinder based on the combustion state of each cylinder detected by the exhaust temperature sensors 15A to 15D.
(First control mode)
The heating control apparatus according to this embodiment includes output correction means 30 that corrects output fluctuations of the engine 1 that fluctuate due to control of the glow plugs 4A to 4D. This output correction means 30 is for the cylinders other than the cylinders in which the exhaust gas temperature Ht detected by the exhaust gas temperature sensors 15A to 15D enters the combustion state exceeds the predetermined temperature Ht1 and the energization to the glow plugs 4A to 4D is stopped. A function of controlling each of the injectors 3A to 3D so as to increase the fuel injection amount from the injector is provided. The output correction means 30 is set in the ECU 20.

  Hereinafter, the control content by the heating control apparatus will be described along the flowchart shown in FIG. This control is applied to afterglow control in which the engine 1 is started and the glow plugs 4A to 4D are energized.

  In step ST1 of FIG. 2, the exhaust temperature from the exhaust temperature sensors 15A to 15D and the energization time T for the glow plugs 4A to 4D after the engine is started are read. As the energization time information T for the glow plugs 4A to 4D, a value measured by a known timer provided in the ECU 20 is used.

  In step ST2, it is determined whether the energization time T has passed a predetermined time T1. The predetermined time T1 is a reference time for the afterglow. If the energization time T has not passed the predetermined time T1, the process proceeds to step ST5, and energization of each of the glow plugs 4A to 4D is continued in the ON state, and when the energization time T has passed the predetermined time T1 The process proceeds to step ST3. In step ST3, it is determined whether or not the exhaust temperature Ht of each cylinder exceeds a predetermined temperature Ht1. The predetermined temperature Ht1 is an exhaust temperature in consideration of durability against the glow plugs 4A to 4D without causing unstable combustion during afterglow. If exhaust gas temperature Ht> predetermined temperature Ht1, if after-glow is possible, the process proceeds to step ST5 and energization of glow plugs 4A to 4D is turned on. If exhaust gas temperature Ht> predetermined temperature Ht1, Proceeding to step ST4, the energization of the glow plugs 4A to 4D is turned off (stopped).

  When the energization to the glow plugs 4A to 4D is turned off (stopped), in step ST6, the energization control for the glow plug is not performed again as in the prior art, but the fuel injection amount to the cylinder of the glow plug in the energized on state is determined. Control the injector to increase. For example, when the energization to the glow plug 4A of the cylinder 1A is turned off (stopped) and the glow plugs 4B to 4D corresponding to the cylinders 1B to 1D are energized, the injectors 3B to 3B corresponding to the cylinders 1B to 1D The fuel injection amount injected from 3D is corrected to be increased with respect to the reference injection amount for injection.

  According to such a configuration, when performing heating control to continue energizing the glow plugs 4A to 4D for combustion stabilization even after starting, the afterglow elapsed time T, which is the heating control period, is equal to or greater than the predetermined time T1, When the exhaust temperature Ht of the cylinder detected by the detection sensors 15A to 15D exceeds the predetermined temperature Ht1, energization to the glow plug corresponding to the cylinder exceeding the predetermined temperature Ht1 is stopped. The energization of the plug can be controlled, and stable combustion after start-up can be ensured while reducing the electric load.

Further, the exhaust temperature Ht of the cylinders detected by the temperature detection sensors 15A to 15D exceeds a predetermined temperature Ht1, and the fuel injection amount from the injector to the cylinders other than the cylinders in which the energization is stopped among the glow plugs 4A to 4D. Since the injector is controlled so as to increase the output of the cylinder, even when the output of the cylinder that has stopped energizing the glow plug is lower than when the glow plug is energized, The amount of heat generated in the unwarmed cylinder increases. For this reason, the reduced output can be compensated not by the energization control by the glow plugs 4A to 4D but by another correction method of increasing the fuel injection amount, so that the warm-up is promoted as a whole and the glow plugs 4A to 4D are further increased. It is possible to ensure stable combustion after start-up while reducing the electrical load on the battery and achieving durability.
(Second control mode)
The heating control apparatus according to this embodiment includes output correction means 40 that corrects output fluctuations of the engine 1 that fluctuate due to control of the glow plugs 4A to 4D (see FIG. 1). This output correction means 40 is a fuel from an injector for a cylinder in which the exhaust temperature Ht detected by the exhaust temperature sensors 15A to 15D is in a combustion state exceeds a predetermined temperature Ht1 and the energization to the glow plugs 4A to 4D is stopped. A function of controlling the injectors 3A to 3D so as to correct the advance angle of the injection timing is provided. The output correction means 40 is set in the ECU 20.

  Hereinafter, the control content by the heating control apparatus will be described along the flowchart shown in FIG. This control is applied to afterglow control in which the engine 1 is started and the glow plugs 4A to 4D are energized.

  In step ST11 of FIG. 3, the exhaust temperature from the exhaust temperature sensors 15A to 15D and the energization time T for the glow plugs 4A to 4D after the engine is started are read. As the energization time information T for the glow plugs 4A to 4D, a value measured by a known timer provided in the ECU 20 is used.

  In step ST12, it is determined whether the energization time T has passed a predetermined time T1. The predetermined time T1 is a reference time for the afterglow. If the energization time T has not passed the predetermined time T1, the process proceeds to step ST15, and energization to each of the glow plugs 4A to 4D is continued in the ON state, and when the energization time T has passed the predetermined time T1 The process proceeds to step ST13. In step ST13, it is determined whether or not the exhaust temperature Ht of each cylinder exceeds a predetermined temperature Ht1. The predetermined temperature Ht1 is an exhaust temperature in consideration of durability against the glow plugs 4A to 4D without causing unstable combustion during afterglow. Here, if the exhaust temperature Ht> the predetermined temperature Ht1, if after-glow is possible, the process proceeds to step ST15 and energization of the glow plugs 4A to 4D is turned on. When the exhaust temperature Ht> the predetermined temperature Ht1, Proceeding to step ST14, the energization of the glow plugs 4A to 4D is turned off (stopped).

  When the energization of the glow plugs 4A to 4D is turned off (stopped), in step ST16, the exhaust temperature Ht for each cylinder is compared with the predetermined temperature Ht1 to determine whether or not the exhaust temperature Ht <the predetermined temperature Ht1. Here, when the exhaust gas temperature Ht <the predetermined temperature Ht1, it is determined that the combustion of the cylinder that has been de-energized due to the de-energization of the glow plug has become unstable, and the energization control for the glow plug is performed again as in the past. Instead, the fuel injection timing to the cylinder in which the combustion becomes unstable is advanced with respect to the basic injection timing. Further, if the exhaust gas temperature Ht <the predetermined temperature Ht1 is not satisfied, it is determined that the combustion is stable even when the energization to the glow plug is stopped, or is stabilized by the advance correction of the fuel injection timing, and the injection timing Reset the correction.

  For example, when the energization of the glow plug 4B corresponding to the cylinder 1B is stopped, and the exhaust temperature Ht from the exhaust temperature sensor 18B after the energization is stopped is equal to or lower than the predetermined temperature Ht1, the fuel injection timing from the injector 3B is set. The advance angle is corrected with respect to the basic injection timing.

  According to such a configuration, the exhaust temperature Ht of the cylinders detected by the temperature detection sensors 15A to 15D exceeds the predetermined temperature Ht1, and the fuel injection from the injector to the cylinders that are de-energized among the glow plugs 4A to 4D. Since the injector is controlled so that the timing is advanced, even if the cylinder that has stopped energizing the glow plug has a delay in combustion compared to the time when the glow plug is energized and combustion is delayed, As described above, the combustion can be stabilized by another correction method such as the advance correction of the fuel injection timing instead of the energization control by the glow plug, so that the electrical load on the glow plugs 4A to 4D can be further reduced and the durability can be improved. As a result, stable combustion after start-up can be ensured.

  In each of the above embodiments, the individual exhaust temperature sensors 15A to 15D are installed for the cylinders 1A to 1D as the combustion state detecting means to detect the exhaust temperature Ht of each cylinder. When one exhaust temperature sensor is arranged at the collective portion 10 and the exhaust valve of each cylinder is opened, the temperature detected by the exhaust temperature sensor is set to the exhaust gas of the cylinder in which the exhaust valve is open. You may make it consider temperature. In this way, the number of exhaust temperature sensors can be reduced.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1A-1D Each cylinder 3A-3D Fuel injection valve 4A-4D Heating means 15A-15D Combustion state detection means (temperature detection means)
20 Heating control means 30 Output correction means T1 Predetermined time Ht1 Predetermined value (predetermined temperature)

Claims (3)

In the internal combustion engine heating control apparatus capable of heating each cylinder before and after the start of the internal combustion engine by heating means that is disposed in each cylinder of the internal combustion engine and generates heat when energized.
Combustion state detecting means for detecting the combustion state of each cylinder;
Heating control means for controlling the amount of heating by the heating means of each cylinder based on the combustion state of each cylinder detected by the combustion state detecting means;
A fuel injection valve disposed in each cylinder and supplying fuel into each cylinder;
Have a output correcting means for correcting the output fluctuation of the internal combustion engine to vary the control to the heating means,
The output correction means calculates the fuel injection amount from the fuel injection valve for cylinders other than the cylinder in which the combustion state of the cylinder detected by the combustion state detection means exceeds a predetermined value and the energization to the heating means is stopped. A heating control apparatus for an internal combustion engine , wherein the fuel injection valve is controlled to increase . In the internal combustion engine heating control apparatus capable of heating each cylinder before and after the start of the internal combustion engine by heating means that is disposed in each cylinder of the internal combustion engine and generates heat when energized.
Combustion state detecting means for detecting the combustion state of each cylinder;
Heating control means for controlling the amount of heating by the heating means of each cylinder based on the combustion state of each cylinder detected by the combustion state detecting means;
A fuel injection valve disposed in each cylinder and supplying fuel into each cylinder ;
Output correction means for correcting output fluctuations of the internal combustion engine that fluctuate due to control to the heating means ;
The output correcting means corrects the advance of the fuel injection timing from the fuel injection valve for the cylinder in which the combustion state of the cylinder detected by the combustion state detecting means exceeds a predetermined value and the energization to the heating means is stopped. Thus, the fuel injection valve is controlled as described above. The heating control device for an internal combustion engine according to claim 1 or 2,
The combustion state detection means is a temperature detection means for detecting the temperature of exhaust discharged from each cylinder ,
The heating control means stops energization to the heating means when the exhaust temperature of the cylinder detected by the temperature detection means exceeds a predetermined value, and the exhaust temperature of the cylinder does not exceed the predetermined value. In this case, the heating control device for the internal combustion engine , wherein the heating means is continuously energized to control the heating amount by the heating means .

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