JP4134762B2 - Exhaust control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exhaust control device for an internal combustion engine, and more particularly to a technique for reducing white smoke discharged from an internal combustion engine.
[0002]
[Prior art]
2. Description of the Related Art In recent years, internal combustion engines mounted on automobiles and the like have been required to reduce white smoke discharged particularly during cold start and low pressure conditions for reasons such as environmental protection. In order to prevent such white smoke from being discharged, an intake heater is provided at the gathering portion of the intake manifold, and the intake heater is warmed by operating the intake heater when the engine is cold starting to promote the vaporization of fuel. Technology that reduces the white smoke emitted has been proposed.
[0003]
As another technique for reducing the white smoke by promoting the temperature rise in the combustion chamber, an exhaust brake valve is provided in the engine exhaust passage, and the exhaust brake valve is closed when the engine is started. A technique has also been proposed in which the temperature of the air-fuel mixture sealed inside the cylinder and the exhaust manifold is raised by reciprocating the piston, thereby reducing the discharge of white smoke (see, for example, Patent Document 1). ).
[0004]
[Patent Document 1]
JP-A-6-280721
[0005]
[Problems to be solved by the invention]
However, in the technology for warming the intake air by the intake heater, since the intake port and the combustion chamber remain at a low temperature, the air heated by the heater is deprived of heat to the intake port to the combustion chamber or the wall surface in the combustion chamber. Since it is cooled, it becomes difficult to maintain heat until the compression stroke following the intake stroke, and white smoke cannot be reduced early.
[0006]
Further, in the configuration using the exhaust brake valve described in Patent Document 1, white smoke immediately after the start of start (immediately after the first explosion) is reduced, but the temperature of the new intake air does not rise, so white smoke can be reduced. The effect does not last.
[0007]
In addition, in order to provide the above-described intake heater and exhaust brake valve, parts, space, and cost are required, and there is a problem that the structure is complicated and the cost increases.
[0008]
The present invention has been made paying attention to the above-described problems, and an object of the present invention is to provide an exhaust control device for an internal combustion engine that can reduce white smoke discharged from the internal combustion engine with a simple configuration. It is in.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the exhaust control device for an internal combustion engine according to the present invention, the amount of fuel supplied into the combustion chamber is adjusted according to the required load, and the output shaft has a predetermined rotational speed. An exhaust control device for an internal combustion engine for controlling the properties of exhaust discharged from the internal combustion engine controlled in this way, the calculation means for calculating the amount of unburned fuel component discharged from the internal combustion engine, and the calculation means Load increasing means for increasing the load of an auxiliary machine driven by the output shaft of the internal combustion engine when the amount of the unburned fuel component calculated in (1) is a predetermined amount or more.
[0010]
An internal combustion engine is controlled so that the amount of fuel supplied into its combustion chamber is adjusted according to a required load, and its output shaft has a predetermined rotational speed. For example, when the internal combustion engine is mounted on a vehicle such as an automobile, the driver requests a high load from the internal combustion engine so as to increase the speed of the vehicle by stepping on an accelerator pedal. As a result, the amount of fuel supplied into the combustion chamber is increased so that the internal combustion engine meets the demand, and the rotation speed of the output shaft is controlled to a desired predetermined rotation speed.
[0011]
On the other hand, the load increasing means is driven by the output shaft of the internal combustion engine when the amount of the unburned fuel component calculated by the calculating means for calculating the amount of the unburned fuel component discharged from the internal combustion engine is equal to or greater than a predetermined amount. Increasing the load on the auxiliary machine increases the load on the internal combustion engine. Then, the internal combustion engine is adjusted so that the amount of fuel supplied into the combustion chamber is increased so that the rotational speed of the output shaft according to the load required by the user is obtained. As a result, since the amount of heat supplied into the combustion chamber increases, the temperature of the combustion chamber rises accordingly. Further, incomplete combustion mainly resulting from the low temperature of the combustion chamber can be prevented, and the amount of unburned fuel components discharged from the internal combustion engine can be reduced.
[0012]
In the exhaust control device for an internal combustion engine according to the present invention, the amount of fuel supplied into the combustion chamber is adjusted during idling, and the exhaust is discharged from the internal combustion engine controlled so that the output shaft has a predetermined rotational speed. An exhaust control device for an internal combustion engine that controls the properties of the exhaust gas, the calculation means for calculating the amount of the unburned fuel component discharged from the internal combustion engine, and the unburned fuel component calculated by the calculation means And a load increasing means for increasing the load of an auxiliary machine driven by the output shaft of the internal combustion engine when the amount is equal to or greater than a predetermined amount.
[0013]
When idling, the internal combustion engine is controlled so that the amount of fuel supplied into the combustion chamber is adjusted and its output shaft has a predetermined rotational speed. The load increasing means is driven by the output shaft of the internal combustion engine when the amount of the unburned fuel component calculated by the calculating means for calculating the amount of the unburned fuel component discharged from the internal combustion engine is equal to or greater than a predetermined amount. Increasing the load on the auxiliary machine increases the load on the internal combustion engine. Then, the amount of fuel supplied into the combustion chamber is adjusted so as to increase so that the predetermined rotational speed at idling is obtained. As a result, as described above, the amount of unburned fuel components discharged from the internal combustion engine can be reduced.
[0014]
And it is suitable for the said calculation means to calculate the quantity of an unburned fuel component based on the combustion chamber temperature of the said internal combustion engine. If the temperature in the combustion chamber is low, the fuel is difficult to vaporize and atomize, making it difficult to burn completely. On the other hand, when the combustion chamber temperature is high, the fuel is easily vaporized and atomized, so that complete combustion is easy. Thus, there is a correlation between the combustion chamber temperature and the amount of the unburned fuel component that is discharged. Therefore, a numerical map showing the relationship between the combustion chamber temperature and the unburned fuel component amount is created in advance based on the correlation, and the calculation means substitutes the detected combustion chamber temperature in the numerical map. Calculate the amount of unburned fuel component. The combustion chamber temperature may be detected by a temperature sensor provided in or near the combustion chamber, or may be detected based on a detection value of a cooling water temperature sensor provided in a cooling water passage in the internal combustion engine. Also good.
[0015]
Further, it is preferable that the calculating means calculates the amount of unburned fuel component based on the rotational speed of the output shaft of the internal combustion engine. If the rotational speed of the output shaft is high, the temperature of the air taken into the combustion chamber rises, so that the fuel is easily vaporized and atomized, and the amount of unburned fuel component is reduced. On the other hand, when the rotational speed of the output shaft is low, the temperature of the air sucked into the combustion chamber does not rise so much, so that the fuel is difficult to vaporize and atomize and the amount of unburned fuel components increases. Thus, since there is a correlation between the rotational speed of the output shaft and the amount of unburned fuel component to be discharged, the relationship between the rotational speed of the output shaft and the amount of unburned fuel component is preliminarily determined based on the correlation. A numerical map is created, and the calculation means substitutes the calculated rotational speed of the output shaft of the internal combustion engine into the numerical map to calculate the amount of the unburned fuel component. The rotation speed is preferably calculated based on the output value of a crank position sensor provided in the internal combustion engine.
[0016]
Further, it is preferable that the calculating means calculates the amount of unburned fuel component based on the pressure of intake air taken into the internal combustion engine. In a region where the intake air pressure is lower than a predetermined pressure, if the intake air pressure is low, the compression top dead center temperature decreases and combustion worsens, increasing the amount of unburned fuel components. Since the dead point temperature becomes high and combustion is easy, the amount of unburned fuel components decreases. In a region where the intake air pressure is higher than a predetermined pressure, if the intake air pressure is low, the fuel tends to vaporize and atomize, so the amount of unburned fuel component decreases.If the intake air pressure is high, the fuel vaporizes / mists. The amount of unburned fuel component increases because it is difficult to convert. Thus, since there is a correlation between the intake pressure and the amount of unburned fuel component that is discharged, a numerical map that shows the relationship between the intake pressure and the amount of unburned fuel component in advance based on the correlation. The calculation means calculates the amount of the unburned fuel component by substituting the intake pressure detected by the pressure sensor provided in the intake passage connected to the internal combustion engine into the numerical map.
[0017]
Further, it is preferable that the calculating means calculates the amount of unburned fuel component based on the temperature of intake air taken into the internal combustion engine. When the temperature of the intake air is low, the amount of unburned fuel components increases because the fuel is difficult to vaporize and atomize. When the temperature of the intake air is high, the amount of unburned fuel components decreases because the fuel is easily vaporized and atomized. Thus, since there is a correlation between the intake air temperature and the amount of unburned fuel component to be discharged, a numerical map showing the relationship between the intake air temperature and the amount of unburned fuel component in advance based on the correlation. The calculation means calculates the amount of the unburned fuel component by substituting the intake air temperature detected by the temperature sensor provided in the intake passage connected to the internal combustion engine into the numerical map.
[0018]
Further, the calculating means is configured to determine the unburned fuel component based on at least two of the combustion chamber temperature of the internal combustion engine, the rotational speed of the output shaft of the internal combustion engine, the pressure of the intake air sucked into the internal combustion engine, or the temperature of the intake air. It is preferred to calculate the quantity. This is because the unburned fuel component amount can be calculated with high accuracy. This may be close to complete combustion if the output shaft speed is high even if the temperature of the combustion chamber is low, and close to complete combustion if the temperature of the combustion chamber is high even if the output shaft speed is low. This is based on the property that the amount of the unburned fuel component changes depending on the correlation among the combustion chamber temperature, the output shaft speed, the intake pressure, or the intake temperature.
[0019]
It is preferable that the load increasing means does not increase the load of the auxiliary machine beyond a predetermined load that does not increase the amount of the unburned fuel component. As described above, when the load on the auxiliary machine increases, the amount of fuel supplied to the combustion chamber is increased and controlled to a predetermined rotational speed. Therefore, if the load on the auxiliary machine is excessively increased, The fuel amount increases excessively with the increase. If the amount of fuel increases excessively, the fuel cannot be combusted in the combustion chamber, and the amount of unburned fuel components to be discharged increases. Therefore, if the load of the auxiliary machine is not increased beyond a predetermined load that increases the unburned fuel component that is discharged without being combusted in the combustion chamber, such an adverse effect can be prevented.
[0020]
The predetermined load corresponds to a change in at least one of the combustion chamber temperature of the internal combustion engine, the rotational speed of the output shaft of the internal combustion engine, the pressure of intake air sucked into the internal combustion engine, or the temperature of the intake air. It is variable.
[0021]
As described above, there is a correlation between the combustion chamber temperature of the internal combustion engine, the rotational speed of the output shaft of the internal combustion engine, the pressure of the intake air sucked into the internal combustion engine or the temperature of the intake air and the amount of unburned fuel components. Therefore, for example, if the predetermined load is set in accordance with at least one of these changes, such as increasing the predetermined load when the combustion chamber temperature rises, the amount of the unburned fuel component to be discharged Can be minimized.
[0022]
Further, it is preferable that the auxiliary machine is a power generation means for generating electric power. Examples of the power generation means include AC generators such as alternators, DC generators such as dynamo, generators and motor generators used in so-called hybrid vehicles.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0024]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine provided with an exhaust control device according to an embodiment of the present invention. An internal combustion engine 1 shown in FIG. 1 is a water-cooled four-cylinder diesel engine having four cylinders 2.
[0025]
The internal combustion engine 1 includes a fuel injection valve 3 that injects fuel directly into the combustion chamber of each cylinder 2. Each fuel injection valve 3 is connected to a pressure accumulating chamber (common rail) 4, and the common rail 4 communicates with a fuel pump 6 through a fuel supply pipe 5.
[0026]
An intake passage 7 is connected to the internal combustion engine 1, and the intake passage 7 is connected to an air cleaner box 8. An air flow meter 9 that outputs an electric signal corresponding to the mass of the intake air flowing through the intake passage 7 is attached to the intake passage 7 downstream of the air cleaner box 8.
[0027]
A compressor housing 10 a of a supercharger (turbocharger) 10 is provided in the middle of the intake passage 7. An intercooler 11 is attached to the intake passage 7 downstream of the compressor housing 10a. Further, an intake throttle valve 12 for adjusting the flow rate of intake air flowing through the intake passage 7 is provided in the intake passage 7 downstream of the intercooler 11. An intake throttle actuator 13 that opens and closes the intake throttle valve 12 is attached to the intake throttle valve 12. The intake passage 7 is provided with an intake pressure sensor 14 for detecting the intake air pressure and an intake air temperature sensor 15 for detecting the temperature of the intake air. The intake pressure sensor 14 and the intake temperature sensor 15 are arranged as close to the internal combustion engine 1 as possible, and after the EGR gas supplied from the EGR passage 23 described later is sufficiently mixed with the intake air, the intake throttle valve It is preferable that 12 sufficiently downstream states can be detected.
[0028]
A cooling water temperature sensor 16 that detects the temperature of the cooling water flowing through the internal combustion engine is provided in the cooling water passage of the internal combustion engine 1. Further, the internal combustion engine 1 is provided with a crank position sensor 17 for detecting the rotational phase of the output shaft (crank shaft). In the present embodiment, the crank position sensor 17 is disposed in the vicinity of the camshaft of the internal combustion engine 1, and a reference pulse sensor (not shown) that outputs a reference pulse every 720 degrees in terms of a crankshaft rotation angle; Two sensors, a crank rotation angle sensor (not shown) that is disposed near the crankshaft of the internal combustion engine 1 and generates a crank angle pulse at every predetermined crank rotation angle (for example, every 15 degrees), are provided. The reference pulse and the crank angle pulse are input to an input port of the ECU 28, which will be described later, and the ECU 28 calculates the rotation speed of the crankshaft (hereinafter referred to as “engine speed”) from the frequency of the crank angle pulse signal at regular intervals. In addition to the calculation, the rotational phase of the crankshaft is calculated from the number of crank angle pulses after the input of the reference pulse.
[0029]
The air sucked from outside air flows into the compressor housing 10a, is compressed in the compressor housing 10a, becomes high temperature, is cooled by the intercooler 11, and then the flow rate is adjusted by the intake throttle valve 12 as necessary. Then, the fuel is distributed to the combustion chambers of the respective cylinders 2 through the intake passages 7 and burned using the fuel injected from the fuel injection valves 3 of the respective cylinders 2 as an ignition source.
[0030]
Further, an exhaust passage 18 is connected to the internal combustion engine 1, and this exhaust passage 18 is connected downstream with a muffler (not shown). Further, a turbine housing 10b of the supercharger 10 is disposed in the middle of the exhaust passage 18, and an occlusion reduction type NOx catalyst (hereinafter referred to as "NOx catalyst") is disposed downstream of the turbine housing 10b of the exhaust passage 18. ”) 19 is also provided. The exhaust passage 18 downstream of the NOx catalyst 19 is supplied with an air-fuel ratio sensor 20 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing through the exhaust passage 18 and an electric signal corresponding to the temperature of the exhaust gas. An exhaust temperature sensor 21 for output is attached. An HC sensor 22 that outputs an output signal corresponding to the HC concentration of the exhaust gas is attached to the exhaust passage 18 upstream of the NOx catalyst 19.
[0031]
Then, the exhaust gas discharged from the turbine housing 10b flows into the NOx catalyst 19 through the exhaust passage 18, and the substance in the exhaust is purified.
[0032]
Further, a portion of the intake passage 7 downstream of the intake throttle valve 12 and a portion of the exhaust passage 18 upstream of the turbine housing 10 b are connected via an EGR passage 23 that recirculates part of the exhaust to the intake passage 7. It is communicated. In the middle of the EGR passage 23, an EGR that is configured by an electromagnetic valve or the like and changes the flow rate of exhaust gas (hereinafter referred to as "EGR gas") that flows through the EGR passage 23 according to the magnitude of applied power. A valve 24 is provided.
[0033]
Then, the EGR gas recirculated from the exhaust passage 18 to the intake passage 7 through the EGR passage 23 is guided to the combustion chamber of each cylinder 2 while being mixed with fresh air flowing from the upstream side of the intake passage 7. The fuel injected from the injection valve 3 is burned using an ignition source.
[0034]
An alternator 25 is connected to the internal combustion engine 1 via a belt 27, and operates using the rotational torque of the crankshaft of the internal combustion engine 1 as a drive source. Then, the energy generated by the combustion in the internal combustion engine 1 is used to generate electric power that is adjusted by the controller 27 and that corresponds to the amount of field current flowing through the rotor coil in the alternator 25. The generated power is charged in a battery (not shown).
[0035]
The internal combustion engine 1 configured as described above is provided with an electronic control unit (ECU: Electronic Control Unit) 28 for controlling the internal combustion engine 1 and the like. The ECU 28 is an arithmetic logic circuit composed of a CPU, ROM, RAM, backup RAM, and the like.
[0036]
Various types of sensors such as the air flow meter 9, the cooling water temperature sensor 16, the crank position sensor 17, the intake pressure sensor 14, the intake air temperature sensor 15, the air-fuel ratio sensor 20, the exhaust gas temperature sensor 21, and the HC sensor 22 are electrically connected to the ECU 28. Connected via wiring, the output signals of the various sensors described above are input to the ECU 28.
[0037]
On the other hand, the fuel injection valve 3, the intake throttle actuator 13, the EGR valve 24, the controller 26, and the like are connected to the ECU 28 via electrical wiring, and the ECU 28 is connected to the fuel injection valve 3, the intake throttle actuator 13, the EGR valve 19 and so on. The controller 26 and the like can be controlled.
[0038]
Then, the ECU 28 executes input of output signals of various sensors, calculation of the engine speed, calculation of the fuel injection amount, calculation of the fuel injection timing, and the like in a basic routine to be executed at regular intervals. For example, during idle operation, in order to maintain the rotational speed of the internal combustion engine 1 at a predetermined idle rotational speed, the ECU 28 outputs signals from the crank position sensor 17, the coolant temperature sensor 16, the engine rotational speed and cooling. A target fuel injection amount is calculated based on a numerical map or the like created corresponding to the water temperature, and the solenoid valve of the fuel injection valve 3 is calculated based on the calculated target fuel injection amount and the pressure in the common rail 4. Is calculated and output as an operation command signal (fuel injection control signal). Further, during normal operation other than idling operation, the ECU 28 detects the amount of accelerator pedal operation (depression amount) provided by the driver near the accelerator pedal (not shown) of the vehicle on which the internal combustion engine 1 is mounted. Based on an accelerator opening sensor (not shown), an output signal from the crank position sensor 17, the coolant temperature sensor 16, etc., a numerical map created corresponding to the required load and fuel injection amount, and the like. The target fuel injection amount is calculated, the opening time of the solenoid valve of the fuel injection valve 3 is calculated based on the calculated target fuel injection amount and the pressure in the common rail 4, and an operation command signal (fuel injection control signal) ).
[0039]
Next, the alternator 25 according to the present embodiment will be described with reference to FIG. In the figure, an alternator 25 includes an internal combustion engine in addition to a stator coil 31 that generates a three-phase alternating current, a rotor coil 32 that forms a magnetic field, a diode 33 that performs three-phase full-wave rectification, an IC regulator 34 that controls an output voltage, and the like. It comprises a rotor, a cooling fan, etc. (not shown) that operate using the rotational torque of one crankshaft as a drive source. Further, a rear bracket (not shown) of the alternator 25 has a B terminal 35 for taking out a generated current, an L terminal 36 for supplying a field current to the rotor coil 32, and a terminal voltage of the battery 37 to the IC regulator 34. An IG terminal 38 for supply is provided.
[0040]
A positive terminal 39 of the battery 37 is directly connected to the B terminal 35 and the IG terminal 38 of the alternator 25, and is also connected to the L terminal 36 via an ignition switch 40 and a resistor 41. A charge lamp 42 is provided in parallel with the resistor 41, and a controller 26 that adjusts the amount of field current flowing through the rotor coil 32 is provided between the resistor 41 and the L terminal 36. The charge lamp 42 is lit when no power is generated to notify the driver of an abnormality in the charging system.
[0041]
In the alternator 25 configured as described above, when a starter switch (not shown) is turned ON by the driver operating the ignition key, the ECU 28 calculates an appropriate amount of field current and sends a command to the controller 26, and the rotor coil A current is caused to flow through the field current amount 32. As a result, electric power corresponding to the amount of field current is generated with the rotation of the crankshaft of the internal combustion engine 1. On the other hand, the internal combustion engine 1 needs a torque for overcoming the load of the alternator 1. When the amount of field current supplied to the rotor coil 3 is increased, the power generation amount of the alternator 25 is increased, and at the same time, the load on the internal combustion engine 1 is increased. Therefore, the engine speed is increased before the field current amount is increased. Therefore, the amount of fuel supplied into the internal combustion engine 1 must be increased so that a load corresponding to the increased amount of field current can be output.
[0042]
Next, the exhaust control device according to the present embodiment will be described.
[0043]
The level of white smoke discharged from the internal combustion engine 1 during a cold start or the like is referred to as the total amount of hydrocarbons (HC) that are mainly unburned fuel components discharged from the combustion chamber (hereinafter simply referred to as “THC”). ) On the basis of. That is, when the amount of THC is large, the white smoke level is poor, and when the amount of THC is small, the white smoke level is relatively good. Further, according to changes in the temperature in the combustion chamber, the rotational speed of the output shaft, etc., whether or not the fuel supplied into the combustion chamber is close to complete combustion changes, and as a result, the amount of THC also changes. Therefore, in the present embodiment, the ECU 28 discharges from the internal combustion engine 1 based on the output signals from the crank position sensor 17, the cooling water temperature sensor 16, the intake pressure sensor 14, the intake air temperature sensor 15, and the like and the fuel injection amount. The amount of THC to be calculated is calculated, and when the calculated THC amount is equal to or greater than the target THC emission amount, the load on the internal combustion engine 1 of the alternator 25 is increased.
[0044]
In this way, the engine speed drops as the load of the alternator 25 increases, so the ECU 28 is at a predetermined speed or idling time according to the load required by the driver. In this case, a command signal is sent to increase the fuel injection amount in order to match the target idle speed. Then, the amount of heat supplied into the combustion chamber increases as compared with the case where the load of the alternator 25 is not increased as the fuel injection amount is increased, and the temperature in the combustion chamber rises earlier. As a result, the fuel injected into the combustion chamber is easy to burn completely at an early stage, and the THC amount is reduced.
[0045]
Specifically, the exhaust control routine according to the present embodiment will be described using the flowchart shown in FIG. This routine is periodically executed when the internal combustion engine 1 is in operation.
[0046]
First, at step 100, the operating state of the internal combustion engine 1 is detected. This is because the ECU 28 detects the operating state of the internal combustion engine 1 from the output signals of the crank position sensor 17, the cooling water temperature sensor 16, the intake pressure sensor 14, the intake air temperature sensor 15, the air flow meter 9, the air-fuel ratio sensor 20, and the like. It is. For example, the engine speed can be grasped from the output signal from the crank position sensor 17, the combustion chamber temperature can be grasped from the output signal from the coolant temperature sensor 16, and the combustion chamber temperature can be detected from the output signals from the intake pressure sensor 14 and the air flow meter 8. The pressure of the intake air and the pressure of the intake air can be grasped, the temperature of the intake air sucked into the combustion chamber can be grasped from the output signal of the intake temperature sensor 15, and the air-fuel ratio in the combustion chamber can be determined from the output signal from the air-fuel ratio sensor 20. I can grasp. From these, it is possible to detect the operating state of the internal combustion engine 1 such as the internal combustion engine 1 being operated with the combustion chamber temperature being low.
[0047]
And it progresses to step 101 and it is determined whether it is the conditions from which the white smoke is discharged | emitted from the driving | running state detected by step 100. FIG. White smoke is emitted when the temperature of the combustion chamber is low and the fuel injected into the combustion chamber is difficult to vaporize and atomize and cannot be completely combusted. If the compression top dead center temperature is low and combustion worsens, it is not exhausted without being completely burned, or if the temperature of the intake air drawn into the combustion chamber is low and the fuel is When the fuel is not sufficiently vaporized or atomized and the fuel is not completely burned and is discharged without being burnt, or because the engine speed is low as shown in FIG. This is because unburned fuel is discharged because the fuel does not rise and is difficult to vaporize and atomize. Therefore, in this step, the ECU 28 determines whether or not the operating state detected in step 100 is a condition for discharging these white smokes based on a map or the like derived in advance based on empirical rules. If it is determined that the white smoke discharge condition is satisfied, the process proceeds to step 102. If it is determined that the white smoke discharge condition is not satisfied, the process proceeds to step 105.
[0048]
In step 102, the amount of THC that will be discharged is calculated. Specifically, when the temperature of the combustion chamber is low, the fuel supplied into the combustion chamber is difficult to vaporize and atomize, so that complete combustion is difficult. On the other hand, when the combustion chamber temperature is high, the fuel is easily vaporized and atomized, so that complete combustion is easy. Thus, there is a correlation between the combustion chamber temperature and the amount of discharged THC. Therefore, a numerical map indicating the relationship between the combustion chamber temperature and the THC amount is created in advance based on the correlation, and is stored in the ROM in the ECU 28. Then, the ECU 28 that also functions as a calculation means calculates the THC amount by substituting the combustion chamber temperature detected based on the detection value of the coolant temperature sensor 16 into the numerical map.
[0049]
Alternatively, when the rotation speed of the output shaft is high, the temperature of the air taken into the combustion chamber rises, so that the fuel is easily vaporized and atomized and is easily burned completely. On the other hand, when the rotational speed of the output shaft is low, the temperature of the air sucked into the combustion chamber does not rise so much, and the fuel is difficult to vaporize and atomize and is difficult to burn completely. Thus, since there is a correlation as shown in FIG. 4 between the rotation speed of the output shaft and the amount of discharged THC, a numerical value indicating the relationship between the output shaft and the THC amount in advance based on the correlation. A map is created and stored in ROM. Then, the calculated engine speed is substituted into the numerical map to calculate the amount of THC.
[0050]
Alternatively, in a region where the intake air pressure is lower than a predetermined pressure, if the intake air pressure is low, the compression top dead center temperature decreases and combustion worsens, so the amount of THC increases, and if the intake air pressure is high, the compression top dead center. Since the point temperature is high and combustion is easy, the amount of THC decreases. Further, in a region where the intake pressure is higher than a predetermined pressure, if the intake pressure is low, the fuel is easily vaporized and atomized, so the amount of THC decreases, and if the intake pressure is high, the fuel is difficult to vaporize and atomize. The amount of THC increases. Thus, since there is a correlation as shown in FIG. 5 between the intake pressure and the exhausted THC amount, a numerical map showing the relationship between the intake pressure and the THC amount in advance based on the correlation. Is created and stored in the ROM. Then, the amount of THC is calculated by substituting the intake pressure detected by the intake pressure sensor 14 into the numerical map.
[0051]
Alternatively, if the temperature of the intake air is low, the fuel is difficult to vaporize and atomize, so that the fuel is difficult to burn and the amount of THC increases. If the temperature of the intake air is high, the fuel easily vaporizes and atomizes, and the amount of THC decreases. Since there is a correlation between the intake air temperature and the exhausted THC amount in this way, a numerical map showing the relationship between the intake air temperature and the THC amount is created in advance based on the correlation, and stored in the ROM. Keep it. Then, the THC amount is calculated by substituting the intake air temperature detected by the intake air temperature sensor 15 into the numerical map.
[0052]
Or, even if the temperature of the combustion chamber is low, if the rotational speed of the output shaft is high, it may be close to complete combustion, and even if the rotational speed of the output shaft is low, it may be close to complete combustion if the temperature of the combustion chamber is high. Since the THC amount varies depending on the correlation between the combustion chamber temperature, the output shaft rotation speed, the intake air pressure, or the intake air temperature, the numerical map described above merely shows the relationship between the combustion chamber temperature and the THC amount. Combining various conditions such as combustion chamber temperature, engine speed, intake air pressure or intake air temperature, such as a numerical map showing the relationship between combustion chamber temperature, engine speed and THC amount A numerical map showing the relationship between the combination of the above and the amount of THC is created and stored in the ROM, and the numerical map corresponding to the combined conditions such as the calculated engine speed and the detected combustion chamber temperature is stored in the numerical map. Generation To calculate the THC amount is.
[0053]
It is also effective to consider the output value of the HC sensor 22 when calculating the THC amount. For example, a difference amount obtained by subtracting the THC amount obtained based on the above-described various numerical maps from the output value (actually discharged THC amount) of the HC sensor 22 from the previous time is learned, and the difference amounts are converted into various numerical maps. The final THC amount may be calculated by adding to the current THC amount obtained based on this.
[0054]
Then, after calculating the amount of THC that will be discharged in step 102, the routine proceeds to step 103. In step 103, it is determined whether or not the THC amount calculated in step 102 is equal to or greater than the target THC amount. This target THC amount may be set in advance as a constant amount, or may be varied depending on the temperature of the combustion chamber, the temperature of the NOx catalyst 19, and the like. However, it goes without saying that it is desirable to reduce as much as possible. If it is determined in this step that the calculated THC amount is greater than or equal to the target THC amount, the process proceeds to step 104. If it is determined that the calculated THC amount is less than the target THC amount, the process proceeds to step 105.
[0055]
In step 104, the load on the alternator 25 is increased. Specifically, the command signal is output so that the amount of field current supplied from the ECU 28 to the rotor coil 32 of the alternator 25 is increased more than usual. As a result, the power generation amount of the alternator 25 is increased, and at the same time, the load on the internal combustion engine 1 is increased. Therefore, the engine speed is set to a target speed equal to or higher than the speed before the field current amount is increased. Therefore, the amount of fuel supplied into the internal combustion engine 1 must be increased so that the load corresponding to the increased amount of field current can be output, and the fuel injection amount is increased. Then, the amount of heat supplied into the combustion chamber increases by the amount of fuel increased, and the temperature in the combustion chamber rises early. As a result, the amount of discharged THC decreases.
[0056]
However, if the load of the alternator 25 is increased too rapidly, that is, if the field current amount is increased rapidly, the fuel injection amount will increase excessively, and the fuel may not be burned in the combustion chamber but may be discharged unburned. There is. Therefore, it is important to increase the load of the alternator 25 within a predetermined load range in which the amount of discharged THC is not increased, that is, to increase the fuel injection amount within a predetermined amount (injection limit amount). The injection limit amount may be varied in accordance with changes in the engine speed or the combustion chamber temperature. In this case, as shown in FIG. 4, the amount of unburned THC decreases as the engine speed increases. Therefore, if the injection limit amount is increased accordingly, the amount of THC discharged is minimized. Can be suppressed. Further, since the amount of THC that is unburned and exhausted also decreases as the combustion chamber temperature increases, the amount of THC that is exhausted can be minimized by increasing the injection limit amount accordingly.
[0057]
In step 105, the execution of this routine is terminated with the alternator load set as normal. If it is determined in step 101 that the white smoke emission condition is not satisfied, or if it is determined that the THC amount calculated in step 103 is smaller than the target THC amount, the process proceeds to step 105. In such a case, in particular, the load on the alternator 25 is reduced. Since it is not necessary to increase the load of the internal combustion engine 1 by increasing the load, the load of the alternator is made normal. If the alternator load is increased in step 104 of the previous routine and the routine proceeds to step 105 in the current routine, the load is returned to the normal load.
[0058]
In this embodiment, the alternator 25, that is, an AC generator is used as the power generation means. However, a DC generator may be used as long as it can store the engine output as energy. A generator or a motor generator can also be used as a generator. In such a case, if the calculated THC amount is equal to or greater than the target THC emission amount, the same effect as described above can be obtained by increasing the load on the internal combustion engine 1 of various generators. .
[0059]
Further, the load on the internal combustion engine 1 need not be limited to the generator, but may be a so-called auxiliary machine such as an air conditioner compressor or an oil pump that recirculates lubricating oil. However, as in this embodiment, the alternator is used as an auxiliary device that increases the load on the internal combustion engine 1, so that the energy stored in the alternator can be used later. An alternator is desirable to prevent deterioration.
[0060]
【The invention's effect】
As described above, according to the present invention, the exhaust gas is discharged from the internal combustion engine with a simple configuration that only increases the load of the auxiliary machine driven by the output shaft of the internal combustion engine without providing a separate device such as an intake heater. White smoke that is generated can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which an exhaust control device for an internal combustion engine according to an embodiment is applied and an intake / exhaust system thereof.
FIG. 2 is a diagram showing a schematic configuration diagram of an alternator according to the embodiment.
FIG. 3 is a flowchart of an exhaust control routine according to the embodiment.
FIG. 4 is a diagram showing a correlation between the engine speed and the amount of discharged THC.
FIG. 5 is a diagram showing a correlation between intake pressure and the amount of discharged THC.
[Explanation of symbols]
1 Internal combustion engine
2-cylinder
3 Fuel injection valve
4 Common rail
5 Fuel supply pipe
6 Fuel pump
7 Intake passage
8 Air cleaner box
9 Air flow meter
10 Turbocharger
11 Intercooler
12 Inlet throttle valve
13 Inlet throttle actuator
14 Intake pressure sensor
15 Intake air temperature sensor
16 Cooling water temperature sensor
17 Crank position sensor
18 Exhaust passage
19 NOx catalyst
20 Air-fuel ratio sensor
21 Exhaust temperature sensor
22 HC sensor
23 EGR passage
24 EGR valve
25 Alternator
26 Controller
27 belt
28 ECU
31 Stator coil
32 Rotor coil
33 Diode
34 IC regulator
35 B terminal
36 L terminal
37 battery
38 IG terminal
39 Positive terminal
40 Ignition switch
41 Resistance
42 Charge lamp

Claims (6)

Exhaust control of the internal combustion engine that controls the nature of the exhaust discharged from the internal combustion engine in which the amount of fuel supplied into the combustion chamber is adjusted according to the required load and the output shaft is controlled to have a predetermined rotational speed A device,
Calculating means for calculating the amount of unburned fuel component discharged from the internal combustion engine;
Load increasing means for increasing the load of an auxiliary machine driven by the output shaft of the internal combustion engine when the amount of the unburned fuel component calculated by the calculating means is a predetermined amount or more. An exhaust control device for an internal combustion engine. An exhaust control device for an internal combustion engine that controls the properties of exhaust discharged from an internal combustion engine that is controlled such that the amount of fuel supplied to the combustion chamber during idling is adjusted and the output shaft has a predetermined rotational speed,
Calculating means for calculating the amount of unburned fuel component discharged from the internal combustion engine;
Load increasing means for increasing the load of an auxiliary machine driven by the output shaft of the internal combustion engine when the amount of the unburned fuel component calculated by the calculating means is a predetermined amount or more. An exhaust control device for an internal combustion engine. The calculating means determines the unburned fuel component based on at least one of the combustion chamber temperature of the internal combustion engine, the rotational speed of the output shaft of the internal combustion engine, the pressure of the intake air sucked into the internal combustion engine, or the temperature of the intake air. The exhaust control device for an internal combustion engine according to claim 1 or 2, wherein the amount is calculated. The exhaust control device for an internal combustion engine according to claim 1, 2 or 3, wherein the load increasing means does not increase the load of the auxiliary machine beyond a predetermined load that does not increase the amount of unburned fuel component. . The predetermined load is varied in accordance with a change in at least one of the combustion chamber temperature of the internal combustion engine, the rotational speed of the output shaft of the internal combustion engine, the pressure of intake air sucked into the internal combustion engine, or the temperature of the intake air. The exhaust control device for an internal combustion engine according to claim 4. The exhaust control device for an internal combustion engine according to any one of claims 1 to 5, wherein the auxiliary machine is power generation means for generating electric power.

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