JP2004270471A - Emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust control device for an internal combustion engine capable of reducing the white smoke discharged from an internal combustion engine through simple constitution. <P>SOLUTION: In the exhaust control device for an internal combustion engine which controls the properties of exhaust gas discharged from the internal combustion engine controlled such that an amount of fuel fed in a combustion chamber according to a demanded load or during idling is regulated and the number of revolutions of an output shaft comes to a given value, the exhaust control device comprises a calculating means to calculate an amount of an unburnt fuel component discharged from the internal combustion engine; and a load increasing means to increase the load of an auxiliary machinery driven by the output shaft of the internal combustion engine when an amount of the unburnt fuel component discharged from the internal combustion engine exceeds a given amount. A temperature in the combustion chamber can be early increased through simple constitution wherein the load of the auxiliary machinery driven by the output shaft of the internal combustion engine is only increased, and the white smoke mainly consisting of the unburnt fuel component discharged from the internal combustion engine can be reduced. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD 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 emitted 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 emitted during cold start or under low pressure conditions, particularly for environmental protection. As a measure to prevent the emission of such white smoke, an intake heater is disposed at the gathering portion of the intake manifold, and when the engine is started at a low temperature, the intake heater is warmed to promote the vaporization of fuel. A technique for reducing the amount of white smoke emitted has been proposed.
[0003]
Another technique for reducing the white smoke by promoting the temperature rise in the combustion chamber is to provide an exhaust brake valve in an exhaust passage of an engine, close the exhaust brake valve when starting the engine, and in that state, close the cylinder inside the cylinder. A technique has been proposed in which the piston is reciprocated to raise the temperature of the air-fuel mixture sealed inside the cylinder and the exhaust manifold, thereby reducing the emission of white smoke (for example, see Patent Document 1). ).
[0004]
[Patent Document 1]
JP-A-6-280721
[0005]
[Problems to be solved by the invention]
However, in the technology of heating the intake air by the above-described intake heater, the temperature of the intake port and the combustion chamber remains low, so that the air heated by the heater is deprived of heat by the intake port to the combustion chamber or the wall of the combustion chamber. Because it is cooled, it is 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 Literature 1, although white smoke is reduced immediately after the start of operation (immediately after the first explosion), the temperature of new intake air does not increase, so that white smoke reduction is not possible. The effect does not last.
[0007]
Further, in order to provide the above-described intake heater and exhaust brake valve, parts, space, and cost are necessary, and thus there is a problem that the structure is complicated and the cost is increased.
[0008]
The present invention has been made in view of the above-mentioned 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 apparatus for an internal combustion engine according to the present invention, the amount of fuel supplied to the combustion chamber is adjusted according to a required load, and the output shaft reaches a predetermined rotational speed. Control device for controlling the properties of exhaust gas discharged from the internal combustion engine controlled as described above, wherein the calculating device calculates the amount of unburned fuel component discharged from the internal combustion engine, and the calculating device And a load increasing means for increasing a load on an auxiliary machine driven by an output shaft of the internal combustion engine when the amount of the unburned fuel component calculated in the step (b) is equal to or more than a predetermined amount.
[0010]
The internal combustion engine is controlled so that the amount of fuel supplied into the combustion chamber is adjusted according to a required load, and the output shaft of the internal combustion engine has a predetermined rotation speed. For example, when the internal combustion engine is mounted on a vehicle such as an automobile, a high load is required on the internal combustion engine such that the driver steps on the accelerator pedal to increase the speed of the vehicle. As a result, the amount of fuel supplied into the combustion chamber is increased so that the internal combustion engine responds to the request, and the rotation speed of the output shaft is controlled to be a desired predetermined rotation speed.
[0011]
On the other hand, when the amount of the unburned fuel component calculated by the calculating unit that calculates the amount of the unburned fuel component discharged from the internal combustion engine is equal to or more than a predetermined amount, the load increasing unit is driven by the output shaft of the internal combustion engine. When the load on the auxiliary equipment is increased, the load on the internal combustion engine also increases. Then, the internal combustion engine is adjusted so that the amount of fuel supplied to the combustion chamber is increased so that the rotation speed of the output shaft corresponds to the load required by the user. As a result, the amount of heat supplied to the combustion chamber increases, so that the temperature of the combustion chamber increases accordingly. In addition, incomplete combustion mainly caused by the low temperature of the combustion chamber can be prevented, and the amount of unburned fuel component discharged from the internal combustion engine can be reduced.
[0012]
In the exhaust control apparatus for an internal combustion engine according to the present invention, the amount of fuel supplied into the combustion chamber at the time of idling is adjusted, and the amount of fuel discharged from the internal combustion engine is controlled such that the output shaft is at a predetermined speed. An exhaust control device for an internal combustion engine that controls the properties of exhaust gas, comprising: a calculating unit that calculates an amount of an unburned fuel component discharged from the internal combustion engine; and an unburned fuel component calculated by the calculating unit. Load increasing means for increasing a load on an auxiliary machine driven by an output shaft of the internal combustion engine when the amount is equal to or more than a predetermined amount.
[0013]
When the internal combustion engine is idling, the amount of fuel supplied to the combustion chamber is adjusted, and the output shaft of the internal combustion engine is controlled to a predetermined rotation speed. When the amount of the unburned fuel component calculated by the calculating unit that calculates the amount of the unburned fuel component discharged from the internal combustion engine is equal to or more than a predetermined amount, the load increasing unit is driven by the output shaft of the internal combustion engine. When the load on the auxiliary equipment is increased, the load on the internal combustion engine also increases. Then, the amount of fuel supplied into the combustion chamber is adjusted so as to increase so that the predetermined number of revolutions at the time of idling is achieved. As a result, as described above, the amount of the unburned fuel component discharged from the internal combustion engine can be reduced.
[0014]
Preferably, the calculation means calculates the amount of the unburned fuel component based on the temperature of the combustion chamber of the internal combustion engine. If the temperature of the combustion chamber is low, the fuel is difficult to vaporize and atomize, and is difficult to completely burn. On the other hand, when the temperature of the combustion chamber is high, the fuel is easily vaporized and atomized, so that complete combustion is easy. Thus, there is a correlation between the temperature of the combustion chamber and the amount of unburned fuel component discharged. Therefore, a numerical map indicating the relationship between the combustion chamber temperature and the unburned fuel component amount is created in advance based on the correlation, and the calculating means substitutes the detected combustion chamber temperature into the numerical map. Calculate the amount of unburned fuel components. The temperature of the combustion chamber 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. Is also good.
[0015]
Further, it is preferable that the calculating means calculates an amount of the unburned fuel component based on a rotation speed of an output shaft of the internal combustion engine. If 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 the amount of the unburned fuel component decreases. On the other hand, if the rotation speed of the output shaft is low, the temperature of the air drawn into the combustion chamber does not increase so much that the fuel is not easily vaporized and atomized, and the amount of unburned fuel components increases. As described above, there is a correlation between the rotation speed of the output shaft and the amount of unburned fuel component discharged, so that the relationship between the rotation speed of the output shaft and the amount of unburned fuel component is determined in advance based on the correlation. A numerical map is prepared, and the calculating means calculates the amount of the unburned fuel component by substituting the calculated rotational speed of the output shaft of the internal combustion engine into the numerical map. Preferably, the rotational speed is calculated based on the output value of a crank position sensor provided in the internal combustion engine.
[0016]
Further, it is preferable that the calculation means calculates the amount of the unburned fuel component based on the pressure of intake air taken into the internal combustion engine. In the region where the intake pressure is lower than a predetermined pressure, if the intake pressure is low, the compression top dead center temperature decreases and combustion deteriorates, so that the amount of unburned fuel components increases, and if the intake pressure is high, the compression top dead center increases. Since the dead center temperature increases and the fuel easily burns, the amount of the unburned fuel component decreases. Also, in a region where the intake pressure is higher than a predetermined pressure, if the intake pressure is low, the fuel is likely to vaporize and atomize, so that the amount of unburned fuel components decreases, and if the intake pressure is high, the fuel evaporates and mist. Since it is difficult to convert, the amount of unburned fuel components increases. Since there is a correlation between the pressure of the intake air and the amount of the unburned fuel component discharged, a numerical map indicating the relationship between the pressure of the intake air and the amount of the unburned fuel component in advance based on the correlation is provided. The calculation means substitutes the intake pressure detected by the pressure sensor provided in the intake passage connected to the internal combustion engine into the numerical map to calculate the amount of the unburned fuel component.
[0017]
Further, it is preferable that the calculating means calculates the amount of the unburned fuel component based on the temperature of the intake air drawn into the internal combustion engine. If the temperature of the intake air is low, the amount of the unburned fuel component increases because the fuel is unlikely to vaporize and atomize. If the temperature of the intake air is high, the amount of the unburned fuel component decreases because the fuel easily vaporizes and atomizes. Since there is a correlation between the temperature of the intake air and the amount of the unburned fuel component discharged, a numerical map showing the relationship between the temperature of the intake air and the amount of the unburned fuel component in advance based on the correlation is provided. 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 may determine the unburned fuel component based on at least two of a combustion chamber temperature of the internal combustion engine, a rotation speed of an output shaft of the internal combustion engine, a pressure of intake air taken into the internal combustion engine, or a temperature of the intake air. It is preferred to calculate the amount. By doing so, the amount of the unburned fuel component can be accurately calculated. 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 unburned fuel component changes depending on the correlation between the temperature of the combustion chamber, the rotation speed of the output shaft, the pressure of the intake air, or the temperature of the intake air.
[0019]
It is preferable that the load increasing unit does not increase the load on 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 accessory increases, the internal combustion engine is controlled to a predetermined rotation speed by increasing the amount of fuel supplied to the combustion chamber. The fuel amount increases excessively with the increase. If the amount of fuel is excessively increased, the fuel cannot be completely burned in the combustion chamber, and the amount of unburned fuel component discharged increases. Therefore, such an adverse effect can be prevented by preventing the load of the auxiliary machine from increasing beyond a predetermined load which would increase the unburned fuel component discharged without being completely burned in the combustion chamber.
[0020]
The predetermined load is determined according to at least one of changes in a temperature of a combustion chamber of the internal combustion engine, a rotation speed of an output shaft of the internal combustion engine, a pressure of intake air taken into the internal combustion engine, and a temperature of the intake air. It is characterized by being variable.
[0021]
As described above, there is a correlation between the combustion chamber temperature of the internal combustion engine, the rotation speed of the output shaft of the internal combustion engine, the pressure of the intake air taken into the internal combustion engine, or the temperature of each intake air and the amount of the unburned fuel component. Therefore, if the predetermined load is set in accordance with at least one of these changes, for example, if the combustion chamber temperature rises, the predetermined load is increased. Can be minimized.
[0022]
Further, it is preferable that the auxiliary device is a power generation unit that generates electric power. Examples of the power generation means include an AC generator such as an alternator, a DC generator such as a dynamo, and a generator and a motor generator used in a so-called hybrid vehicle.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively 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 thereto unless otherwise specified. Absent.
[0024]
FIG. 1 is a diagram illustrating a schematic configuration of an internal combustion engine including an exhaust control device according to an embodiment of the present invention. The 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 for directly injecting fuel into a combustion chamber of each cylinder 2. Each fuel injection valve 3 is connected to a pressure accumulation chamber (common rail) 4, which communicates with a fuel pump 6 via 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]
In the middle of the intake passage 7, a compressor housing 10a of a supercharger (turbocharger) 10 is provided. 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 for driving the intake throttle valve 12 to open and close 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 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 to be able to detect a state sufficiently downstream of Twelve.
[0028]
In the cooling water passage of the internal combustion engine 1, a cooling water temperature sensor 16 for detecting the temperature of the cooling water flowing in the internal combustion engine is provided. Further, the internal combustion engine 1 is provided with a crank position sensor 17 for detecting a rotation phase of an output shaft (crank shaft). In the present embodiment, the crank position sensor 17 is disposed near the camshaft of the internal combustion engine 1 and outputs a reference pulse every 720 degrees as a crankshaft rotation angle (not shown); A crank rotation angle sensor (not shown) is provided 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). The reference pulse and the crank angle pulse are input to an input port of the ECU 28 described later, and the ECU 28 determines the rotation speed of the crankshaft (hereinafter, referred to as “engine rotation speed”) at regular intervals based on the frequency of the crank angle pulse signal. The rotation phase of the crankshaft is calculated from the number of crank angle pulses after the reference pulse is input.
[0029]
The air sucked from the outside air flows into the compressor housing 10a, is compressed in the compressor housing 10a, has a high temperature, is cooled by the intercooler 11, and the flow rate is adjusted by the intake throttle valve 12 as necessary. The fuel is distributed to the combustion chambers of the respective cylinders 2 via the intake passages 7 and is 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 the exhaust passage 18 is connected downstream to a muffler (not shown). A turbine housing 10b of the supercharger 10 is disposed in the middle of the exhaust passage 18, and a portion of the exhaust passage 18 downstream of the turbine housing 10b is provided with a NOx storage reduction catalyst (hereinafter referred to as "NOx catalyst"). ). 19 is provided. In the exhaust passage 18 downstream of the NOx catalyst 19, 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 are provided. An output exhaust gas temperature sensor 21 is provided. 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 substances in the exhaust gas are purified.
[0032]
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 10b are connected via an EGR passage 23 for recirculating a part of exhaust gas to the intake passage 7. Are in communication. In the middle of the EGR passage 23, an EGR is formed by an electromagnetic valve or the like, and changes the flow rate of exhaust gas (hereinafter, referred to as “EGR gas”) flowing through the EGR passage 23 according to the magnitude of the applied power. A valve 24 is provided.
[0033]
The EGR gas recirculated from the exhaust passage 18 to the intake passage 7 via the EGR passage 23 is guided to the combustion chamber of each cylinder 2 while being mixed with fresh air flowing from the upstream of the intake passage 7, The fuel is burned using the fuel injected from the injection valve 3 as an ignition source.
[0034]
Further, the 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, by using the energy generated by the combustion in the internal combustion engine 1, the controller 27 generates electric power corresponding to the field current flowing through the rotor coil in the alternator 25 by adjusting the controller 27. Then, 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 and logic operation circuit including a CPU, a ROM, a RAM, a backup RAM, and the like.
[0036]
The ECU 28 includes various sensors such as the air flow meter 9, the coolant temperature sensor 16, the crank position sensor 17, the intake pressure sensor 14, the intake temperature sensor 15, the air-fuel ratio sensor 20, the exhaust temperature sensor 21, and the HC sensor 22. The output signals of the various sensors described above are connected to the ECU 28 via wiring.
[0037]
On the other hand, the ECU 28 is connected to the fuel injection valve 3, the intake throttle actuator 13, the EGR valve 24, the controller 26, and the like via electric wiring. The ECU 28 is connected to the fuel injection valve 3, the intake throttle actuator 13, the EGR valve 19 , The controller 26 and the like can be controlled.
[0038]
Then, the ECU 28 executes the input of output signals of various sensors, the calculation of the engine speed, the calculation of the fuel injection amount, the calculation of the fuel injection timing, and the like in the basic routine to be executed at regular intervals. For example, at the time of idling, in order to maintain the rotation speed of the internal combustion engine 1 at a predetermined idle rotation speed, the ECU 28 outputs an output signal from the crank position sensor 17, the cooling water temperature sensor 16, etc. The target fuel injection amount is calculated based on a numerical map or the like created in correspondence with 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 a normal operation other than the idling operation, the ECU 28 detects an operation amount (depressed amount) of a driver's accelerator pedal provided near an accelerator pedal (not shown) of the vehicle equipped with the internal combustion engine 1. Based on an output signal from an accelerator opening sensor (not shown), a crank position sensor 17, a coolant temperature sensor 16, etc., and a required map and a fuel injection amount. A target fuel injection amount is calculated based on the calculated target fuel injection amount and the pressure in the common rail 4, and the opening time of the solenoid valve of the fuel injection valve 3 is calculated. ).
[0039]
Next, the alternator 25 according to the present embodiment will be described with reference to FIG. In the figure, an alternator 25 includes a stator coil 31 for generating three-phase alternating current, a rotor coil 32 for generating a magnetic field, a diode 33 for performing three-phase full-wave rectification, an IC regulator 34 for controlling an output voltage, and an internal combustion engine. It is composed of a rotor (not shown), a cooling fan, and the like, which 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 extracting 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]
The 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 for adjusting the amount of field current flowing through the rotor coil 32 is provided between the resistor 41 and the L terminal 36. Note that the charge lamp 42 is lit during non-power generation to notify the driver of an abnormality in the charging system.
[0041]
In the alternator 25 configured as described above, when a driver operates an ignition key to turn on a starter switch (not shown), the ECU 28 calculates an appropriate field current amount, sends a command to the controller 26, and sends a command to the controller 26. The current is caused to flow by the amount corresponding to the field current in 32. As a result, electric power corresponding to the field current amount is generated as the crankshaft of the internal combustion engine 1 rotates. On the other hand, the internal combustion engine 1 needs a torque to overcome the load of the alternator 1. When the amount of the field current supplied to the rotor coil 3 is increased, the load on the internal combustion engine 1 is increased at the same time as the amount of power generated by the alternator 25 is increased. Therefore, the engine speed is reduced by the number of revolutions before the amount of the field current is increased. In order to make the same, it is necessary to increase the amount of fuel supplied into the internal combustion engine 1 so that a load corresponding to the increased amount of the field current can be output.
[0042]
Next, an exhaust control device according to the present embodiment will be described.
[0043]
The level of white smoke that is largely discharged from the internal combustion engine 1 at the time of a cold start or the like is mainly the total amount of hydrocarbons (HC) that are unburned fuel components discharged from the combustion chamber (hereinafter simply referred to as “THC”). ) Can be used as a reference. That is, it is considered that the white smoke level is bad when the amount of THC is large, and the white smoke level is relatively good when the amount of THC is small. Also, depending on changes in the temperature in the combustion chamber, the number of revolutions of the output shaft, and the like, whether or not the fuel supplied into the combustion chamber approaches complete combustion changes, and as a result, the amount of THC also changes. From these facts, in the present embodiment, the ECU 28 determines whether or not the fuel injection amount and the output signals from the crank position sensor 17, the coolant temperature sensor 16, the intake pressure sensor 14, the intake temperature sensor 15, etc. and the fuel injection amount are to be discharged from the internal combustion engine 1. The calculated THC amount is calculated, and if the calculated THC amount is equal to or greater than the target THC emission amount, the load of the alternator 25 on the internal combustion engine 1 is increased.
[0044]
By doing so, the engine speed drops as much as the load on the alternator 25 increases, so the ECU 28 sets the engine speed to 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 is increased by the increased amount of fuel injection as compared with a case where the load of the alternator 25 is not increased, and the temperature in the combustion chamber rises early. As a result, the fuel injected into the combustion chamber is likely to be completely burned early and the THC amount is reduced.
[0045]
Specifically, an exhaust control routine according to the present embodiment will be described with reference to a flowchart shown in FIG. This routine is periodically executed when the internal combustion engine 1 is operating.
[0046]
First, at step 100, the operating state of the internal combustion engine 1 is detected. This means that the ECU 28 detects the operating state of the internal combustion engine 1 from output signals of the crank position sensor 17, the coolant temperature sensor 16, the intake pressure sensor 14, the intake 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 cooling water temperature sensor 16, and the output from the intake pressure sensor 14 and the air flow meter 8 into the combustion chamber. The intake air pressure and the atmospheric pressure can be grasped, the temperature of the intake air sucked into the combustion chamber can be grasped from the output signal of the intake air temperature sensor 15, and the air-fuel ratio in the combustion chamber can be grasped from the output signal from the air-fuel ratio sensor 20. I can understand. Then, it is possible to detect the operating state of the internal combustion engine 1 such that the internal combustion engine 1 is operated in a state where the temperature of the combustion chamber is low.
[0047]
Then, the process proceeds to step 101, and it is determined whether or not the condition for discharging white smoke is satisfied from the operation state detected in step 100. 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 burned and is discharged unburned. If the temperature is low and the compression top dead center temperature drops and the combustion deteriorates, the fuel may be discharged unburned without complete combustion, or if the temperature of the atmosphere is low and the temperature of the intake air drawn into the combustion chamber is low, fuel The case where the fuel is not completely burned and exhausted unburned without being completely burned due to insufficient vaporization or atomization, or the temperature of the air taken into the combustion chamber is too low due to the low engine speed as shown in FIG. Unburned fuel is discharged because the fuel does not evaporate or atomize without rising. 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 by an empirical rule. If it is determined that the condition is the white smoke discharge condition, the process proceeds to step 102, and if it is determined that the condition is not the white smoke discharge condition, 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 it is difficult to completely burn the fuel. On the other hand, when the temperature of the combustion chamber 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 THC discharged. 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, which also functions as a calculating unit, calculates the THC amount by substituting the combustion chamber temperature detected based on the detection value of the cooling water temperature sensor 16 into the numerical value map.
[0049]
Alternatively, if 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 rotation speed of the output shaft is low, the temperature of the air taken into the combustion chamber does not increase so much, so that the fuel is not easily vaporized and atomized, and is difficult to completely burn. As described above, there is a correlation between the rotational speed of the output shaft and the discharged THC amount as shown in FIG. 4, and 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 the ROM. Then, the calculated engine speed is substituted into the numerical value map to calculate the amount of THC.
[0050]
Alternatively, in a region where the intake pressure is lower than a predetermined pressure, if the intake pressure is low, the compression top dead center temperature decreases and combustion deteriorates, so that the THC amount increases, and if the intake pressure is high, the compression top dead center increases. Since the point temperature is increased and the fuel is easily combusted, the THC amount is reduced. Further, in a region where the intake pressure is higher than a predetermined pressure, if the intake pressure is low, the fuel is liable to vaporize and atomize, so the THC amount is reduced, and if the intake pressure is high, the fuel is difficult to vaporize and mist. The THC amount increases. Since there is a correlation as shown in FIG. 5 between the intake pressure and the discharged THC amount, a numerical map indicating 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 intake pressure detected by the intake pressure sensor 14 is substituted into the numerical value map to calculate the THC amount.
[0051]
Alternatively, if the temperature of the intake air is low, the fuel is unlikely to vaporize and atomize, so that the fuel is unlikely to burn and the THC amount increases. If the temperature of the intake air is high, the fuel easily vaporizes and atomizes, and the THC amount decreases. Since there is a correlation between the intake air temperature and the exhausted THC amount, a numerical map indicating 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 intake air temperature detected by the intake air temperature sensor 15 is substituted into the numerical value map to calculate the THC amount.
[0052]
Alternatively, even if the temperature of the combustion chamber is low, the combustion speed may be close to complete combustion if the rotation speed of the output shaft is high. In some cases, for example, the THC amount changes depending on the correlation between the combustion chamber temperature, the rotation speed of the output shaft, the intake pressure, or the intake air temperature. Therefore, the above-described numerical map simply shows the relationship between the combustion chamber temperature and the THC amount. Instead of the numerical map shown, a numerical map showing the relationship between the combustion chamber temperature and the engine speed and the THC amount, and the like, by combining various conditions of the combustion chamber temperature, the engine speed, the pressure of the intake air or the temperature of the intake air, A numerical map showing the relationship between the combination of the above and the THC amount is created and stored in the ROM, and a map corresponding to the combined conditions such as the calculated engine speed and the detected combustion chamber temperature is stored in the numerical map. Teens To calculate the THC amount is.
[0053]
In calculating the THC amount, it is also effective to consider the output value of the HC sensor 22. For example, a difference amount obtained by subtracting the THC amount obtained previously based on the above-described various numerical maps from the output value of the HC sensor 22 (the actually discharged THC amount) is learned, and the difference amount is stored in the various numerical maps. It is preferable to calculate the final THC amount by adding the current THC amount obtained based on the above.
[0054]
After calculating the amount of THC that will be discharged in step 102, the process proceeds to step 103. In step 103, it is determined whether the THC amount calculated in step 102 is equal to or larger than the target THC amount. This target THC amount may be determined in advance as a constant amount, or may be varied according to the temperature of the combustion chamber, the temperature of the NOx catalyst 19, and the like. However, it is needless to say that it is desirable to reduce as much as possible. Then, in this step, when it is determined that the calculated THC amount is equal to or more than the target THC amount, the process proceeds to step 104, and when it is determined that the calculated THC amount is smaller 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 ECU 28 outputs a command signal so that the field current supplied to the rotor coil 32 of the alternator 25 is increased more than usual. Then, the load on the internal combustion engine 1 increases at the same time as the power generation amount of the alternator 25 increases, so that the engine speed is set to the target speed equal to or higher than the speed before the field current amount is increased. Therefore, the fuel supplied into the internal combustion engine 1 must be increased so that a load corresponding to the increased field current can be output, and the fuel injection amount is increased. Then, the amount of heat supplied to the combustion chamber is increased by an amount corresponding to the increased amount of fuel, and the temperature in the combustion chamber is increased at an early stage. As a result, the amount of discharged THC is reduced.
[0056]
However, if the load of the alternator 25 is increased too rapidly, that is, if the field current is increased abruptly, 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 on the alternator 25 within a predetermined load range that does not increase the discharged THC amount, that is, to increase the fuel injection amount within a predetermined amount (injection limit amount). The injection limit may be varied according to changes in the engine speed, the temperature of the combustion chamber, and the like. In such a case, as shown in FIG. 4, as the engine speed increases, the amount of unburned THC also decreases. Therefore, if the injection limit is increased accordingly, the amount of THC discharged is minimized. Can be suppressed. Further, as the combustion chamber temperature increases, the amount of THC discharged unburned also decreases. Therefore, if the injection limit is increased accordingly, the amount of THC discharged can be minimized.
[0057]
In step 105, the load of the alternator is set to a normal value, and the execution of this routine ends. When it is determined in step 101 that the condition is not the white smoke emission condition or when 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, the load on the alternator 25 is particularly reduced. Since it is not necessary to increase the load on the internal combustion engine 1, the load on the alternator is made normal. If the alternator load is increased in step 104 of the previous routine and the process proceeds to step 105 in this routine, the load is returned to the normal load.
[0058]
In the present embodiment, the alternator 25, that is, an AC generator is used as the power generation means, but a DC generator may be used as long as it can store the engine output as energy, and in a so-called hybrid vehicle, Generators and motor generators can also be used as generators. In such a case, if the calculated THC amount is equal to or more 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 the various generators. .
[0059]
The load on the internal combustion engine 1 is not limited to be increased by the generator, but may be an auxiliary device such as an air conditioner compressor or an oil pump for returning lubricating oil. However, as in the present embodiment, by using the alternator as an auxiliary device for increasing the load on the internal combustion engine 1, the energy stored in the alternator can be used later, so that the fuel consumption becomes excessive. An alternator is desirable in order not to make it worse.
[0060]
【The invention's effect】
As described above, according to the present invention, the exhaust gas from the internal combustion engine is simply provided without increasing the load on the auxiliary device driven by the output shaft of the internal combustion engine without separately providing a device such as an intake heater. White smoke generated can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating 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 and 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 an engine speed and a discharged THC amount.
FIG. 5 is a diagram showing a correlation between an intake pressure and a discharged THC amount.
[Explanation of symbols]
1 Internal combustion engine
2 cylinders
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 Supercharger
11 Intercooler
12 Intake throttle valve
13 Actuator for intake throttle
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 gas 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 Plus terminal
40 ignition switch
41 Resistance
42 charge lamp

Claims (6)

The amount of fuel supplied to the combustion chamber is adjusted according to the required load, and the output shaft is controlled so as to have a predetermined number of revolutions. A device,
Calculating means for calculating the amount of the unburned fuel component discharged from the internal combustion engine,
Load increasing means for increasing the load on 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 equal to or more than a predetermined amount. Exhaust control device for an internal combustion engine. An exhaust control device for an internal combustion engine, wherein an amount of fuel supplied to the combustion chamber at the time of idling is adjusted, and an output shaft of the internal combustion engine is controlled to have a predetermined number of revolutions to control a property of exhaust discharged from the internal combustion engine.
Calculating means for calculating the amount of the unburned fuel component discharged from the internal combustion engine,
Load increasing means for increasing the load on 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 equal to or more than a predetermined amount. Exhaust control device for an internal combustion engine. The calculating means is configured to determine a temperature of a combustion chamber of the internal combustion engine, a rotation speed of an output shaft of the internal combustion engine, a pressure of intake air taken into the internal combustion engine, or a temperature of the intake air based on at least one of the unburned fuel component. The exhaust control device for an internal combustion engine according to claim 1 or 2, wherein the amount is calculated. The exhaust control system for an internal combustion engine according to claim 1, 2, or 3, wherein the load increasing unit does not increase the load on the auxiliary machine beyond a predetermined load that does not increase the amount of the unburned fuel component. . The predetermined load is changed in accordance with at least one of a change in a temperature of a combustion chamber of the internal combustion engine, a rotation speed of an output shaft of the internal combustion engine, a pressure of intake air taken into the internal combustion engine, or a temperature of the intake air. The exhaust control device for an internal combustion engine according to claim 4, wherein The exhaust control device for an internal combustion engine according to any one of claims 1 to 5, wherein the auxiliary device is a power generation unit that generates electric power.

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