WO2008156154A1

WO2008156154A1 - Control system for internal combustion engine

Info

Publication number: WO2008156154A1
Application number: PCT/JP2008/061275
Authority: WO
Inventors: Daichi Imai
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2007-06-21
Filing date: 2008-06-13
Publication date: 2008-12-24
Also published as: JP2009002234A

Abstract

Intended is to make the combustion deterioration of a fuel, as might otherwise be caused by the using environment of an internal combustion engine, as little as possible. For this intention, a control system for an internal combustion engine of a compression ignition type having a glow plug is activated when the altitude or the fuel cetane value belongs to a predetermined combustion deteriorating range.

Description

Description Internal combustion engine control system Technical field

The present invention relates to a control technique for an internal combustion engine provided with a glow plug. Background art

As a compression ignition type internal combustion engine, an internal combustion engine having a glow plug for increasing the temperature in the combustion chamber is known.

Japanese Laid-Open Patent Publication No. 6-10 8 9 60 discloses a technique for controlling the energization amount of the glove lug in accordance with the temperature of the internal combustion engine, the engine speed, and the like.

Japanese Patent Application Laid-Open No. 6-10 8 9 59 discloses a technique for controlling the energization amount of the glow plug in accordance with the intake air amount of the internal combustion engine. Disclosure of the invention

The present invention provides a control system for an internal combustion engine equipped with a glow plug, and provides a technique for controlling the glow plug in accordance with the use conditions of the internal combustion engine, thereby making it possible to improve fuel combustion and discharge white smoke. It aims to reduce it automatically.

In order to achieve the above object, the present invention provides a control system for a compression ignition type internal combustion engine equipped with a glow plug, which is caused by the altitude of the place where the internal combustion engine is used and the cetane number of the fuel used by the internal combustion engine. When the above-mentioned combustion deterioration condition is satisfied, the combustion state of the fuel f is improved by operating the glove lug.

Specifically, the present invention provides a control system for an internal combustion engine having a glow plug, wherein the first detection means for detecting an altitude at which the internal combustion engine is used and the Z or the internal combustion engine are provided. Second detection means for detecting the cetane number of the fuel to be used; and control means for operating the glow plug when the detection values of the first detection means and Z or the second detection means belong to a predetermined combustion deterioration range. I prepared.

According to this invention, since the glow plug is operated when the altitude and / or the fuel cetane number falls within the combustion deterioration range, the fuel combustion deterioration is suppressed. As a result, the emission of white smoke due to worsening combustion is also reduced. That is, according to the control system for an internal combustion engine of the present invention, the deterioration of fuel combustion and the emission of white smoke can be reduced as much as possible.

In the present invention, examples of the combustion deterioration range include a range where the altitude is higher than a predetermined altitude, and / or a range where the fuel cetane number is lower than a predetermined cetane number.

As the altitude at which the internal combustion engine is used increases, the density of air drawn into the internal combustion engine decreases. In this case, the combustion state of the fuel deteriorates due to a decrease in the compression end temperature (temperature in the cylinder at the compression top dead center) and a decrease in the in-cylinder oxygen amount. As a result, unburned fuel becomes white smoke and is easily discharged from the internal combustion engine.

Moreover, when the cetane number of the fuel used by the internal combustion engine decreases, the fuel becomes difficult to atomize and vaporize and the ignition temperature of the fuel increases. For this reason, when the cetane number of the fuel decreases, the amount of fuel that cannot be combusted in the cylinder increases. As a result, white smoke discharged from the internal combustion engine tends to increase.

Therefore, if the range where the altitude is higher than the specified altitude and / or the fuel cetane number is lower than the predetermined cetane number is defined as the burn-up deterioration range, the unburned fuel is reduced by operating the glow plug. be able to. In an internal combustion engine equipped with a supercharger, even if the pressure of the intake air compressed by the supercharger (supercharging pressure) does not reach the target supercharging pressure, the compression end temperature decreases and the in-cylinder oxygen amount Decrease.

Therefore, the control system for an internal combustion engine according to the present invention further includes third detection means for detecting the supercharging pressure of the intake air compressed by the supercharger, and the detection value of the third detection means is less than the target supercharging pressure. In this case, the glow plug may be operated.

In this case, in addition to an increase in altitude and a decrease in fuel cetane number, deterioration of combustion due to a decrease in supercharging pressure is also suppressed. As a result, the emission of white smoke due to a decrease in supercharging pressure is also suppressed.

Brief Description of Drawings

FIG. 1 is a diagram showing a schematic configuration of a control system for an internal combustion engine.

Fig. 2 is a diagram showing the combustion deterioration range.

FIG. 3 is a diagram showing a combustion deterioration range when the glow plug is operated.

FIG. 4 is a flowchart showing a combustion deterioration suppression control routine. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a control system for an internal combustion engine according to the present invention. An internal combustion engine 1 shown in FIG. 1 is a compression ignition type internal combustion engine (diesel engine) having a plurality of cylinders 2.

A piston 3 is slidably inserted into each cylinder 2 of the internal combustion engine 1. The internal combustion engine 1 includes a fuel injection valve 4 that injects fuel into each cylinder 2 and a glow plug 5 that heats gas in each cylinder 2 (combustion chamber).

The inside of each cylinder 2 communicates with the intake passage 7 via the intake port 6. Air intake A compressor housing 80 of a centrifugal supercharger (turbocharger) 8 is arranged in the middle of the path 7.

An intake cooler 9 for cooling the intake air compressed in the compressor housing 80 is disposed in the intake passage 7 downstream of the compressor housing 80. An intake throttle valve 10 for changing the cross-sectional area of the intake passage 7 is disposed in the intake passage 7 downstream of the intercooler 9.

The interior of each cylinder 2 communicates with the exhaust passage 12 via the exhaust port 11. In the middle of the exhaust passage 12, a turbine housing 81 of the turbocharger 8 is disposed. An exhaust purification device 13 is disposed in the exhaust passage 12 downstream of the turbine housing 81.

The exhaust gas purification device 13 includes a catalyst for purifying exhaust gas (for example, an NOx storage reduction catalyst, an oxidation catalyst, a three-way catalyst, etc.) and / or particulates (PM:

Particulate Matter) is included to collect Particulate Matter). An exhaust gas recirculation (EGR) passage 14 is connected to the exhaust passage 12 upstream of the turbine housing 81. The EGR passage 14 is a passage that guides part of the exhaust gas flowing through the exhaust passage 12 to the intake passage 7 downstream of the intake throttle valve 10. An EGR valve 15 and an EGR cooler 16 are disposed in the middle of the EGR passage 14. The internal combustion engine 1 configured in this way is provided with an ECU 17. The ECU 17 is an electronic control unit composed of a CPU, ROM, RAM, backup RAM, and the like. The ECU 17 is electrically connected to various sensors such as an air flow overnight 18, an intake air temperature sensor 19, an intake air pressure sensor 20, an atmospheric pressure sensor 21, and a crank position sensor 22.

The air flow meter 18 is disposed in the intake passage 7 upstream of the compressor housing 80 and measures the amount of air sucked into the intake passage 7 from the atmosphere. Intake air temperature The sensor 19 is arranged in the intake passage 7 near the air flow 18 and measures the temperature of the air taken into the intake passage 7 from the atmosphere (atmospheric temperature). The intake pressure sensor 20 is disposed in the intake passage 7 downstream from the intake throttle valve 10 and the pressure of the intake air flowing through the intake passage 7 (in other words, the pressure of the intake air compressed by the compressor housing 80 (supercharging) Measure the pressure)). The atmospheric pressure sensor 21 measures the atmospheric pressure. The crank position sensor 22 measures the rotational position (rotation angle) of an engine output shaft (crankshaft) (not shown).

The E C U 17 electrically controls the fuel injection valve 4, the glow plug 5, the intake throttle valve 10, and the EGR valve 15 described above based on the measured values of the various sensors described above. For example, E C U 17 performs combustion deterioration reduction control that is the gist of the present invention, in addition to known fuel injection control and E G R control.

Hereinafter, the combustion deterioration suppression control in this embodiment will be described.

When the altitude of the place where the internal combustion engine 1 is used increases, the density of air sucked into the internal combustion engine 1 decreases. In this case, the compression end temperature decreases and the amount of oxygen introduced into the cylinder 2 decreases. For this reason, the combustion state of fuel deteriorates. As a result, the unburned fuel becomes white smoke and is discharged from the internal combustion engine 1.

Further, when the cetane number of the fuel used by the internal combustion engine 1 decreases, the fuel injected from the fuel injection valve 4 becomes difficult to atomize and vaporize, and the ignition temperature of the fuel increases. For this reason, when the fuel cetane number decreases, the amount of fuel that cannot be combusted in cylinder 2 increases. As a result, white smoke emitted from the internal combustion engine increases.

Figure 2 shows the correlation between altitude, fuel cetane number, and white smoke limit value. The white smoke limit value corresponds to an allowable limit amount of white smoke discharged from the internal combustion engine 1.

In Fig. 2, in an environment where the altitude is less than EL 1 (for example, less than 100 m above sea level), the white smoke emission of the internal combustion engine 1 will not exceed the white smoke limit even if the fuel cetane number decreases. . On the other hand, if the fuel sedan number decreases in an environment where the altitude exceeds EL 1, The white smoke emission of Seki 1 exceeds the white smoke limit value and belongs to the combustion deterioration range.

On the other hand, in the combustion deterioration suppression control of the present embodiment, the ECU 17 is determined from the altitude of the place where the internal combustion engine 1 is used and the set value of the fuel used by the internal combustion engine 1 (hereinafter referred to as “ When the value belongs to the combustion deterioration range in FIG. 2 (that is, when the white smoke limit value is exceeded), the glow plug 5 is operated. When the glow plug 5 is actuated, the atmospheric temperature in the cylinder 2 increases, so that atomization and vaporization of the fuel injected from the fuel injection valve 4 is promoted and the compression end temperature rises. As a result, the amount of unburned fuel is reduced and the amount of white smoke emitted from the internal combustion engine 1 is also reduced.

FIG. 3 is a diagram showing the correlation between the altitude, the fuel cetane number, and the white smoke limit value when the glow plug 5 is operating.

In Fig. 3, the white smoke limit value when the glow plug 5 is activated (see the solid line in Fig. 3) is the white smoke limit value when the glow plug 5 is not activated (see the broken line in Fig. 3).

) Higher than In other words, when the glow plug 5 is activated, the altitude at which the amount of white smoke discharged from the internal combustion engine 1 exceeds the white smoke limit value is higher than when the glow plug 5 is inactive, and when the glow plug 5 is activated. The fuel cetane number at which the white smoke emission of the internal combustion engine 1 exceeds the white smoke limit is lower than when the glow plug 5 is not in operation.

Therefore, if the glove lag 5 is activated when the characteristic value determined from the altitude and the fuel sedan number falls within the combustion deterioration range, the fuel combustion deterioration can be suppressed and the white smoke emission of the internal combustion engine 1 can be suppressed. Can be reduced below the white smoke limit.

Here, the execution procedure of the combustion deterioration suppression control will be described with reference to FIG. Figure 4 is a flowchart showing the combustion deterioration suppression control routine. The combustion deterioration suppression control routine is a routine stored in advance in the ROM of E C U 17, and is periodically executed by E C U 17.

In the combustion deterioration suppression control routine of FIG. 4, the ECU 17 first performs the process of S 1 0 1. Execute. In SI 01, the ECU 17 determines the fuel cetane number used by the internal combustion engine 1. As this discrimination method, various known methods can be used. For example, a method of detecting the fuel ignition timing from the in-cylinder pressure or the angular acceleration of the crankshaft and determining the fuel cetane number based on the detected ignition timing can be exemplified. By the ECU 17 discriminating the fuel set value by such a method, the second detection means according to the present invention is realized.

In S102, the ECU 17 determines the altitude of the place where the internal combustion engine 1 is used. Since the altitude correlates with the atmospheric pressure, the ECU 17 may determine the altitude based on the measured value of the atmospheric pressure sensor 21. In that case, the atmospheric pressure sensor 21 corresponds to the first detection means according to the present invention.

In S 103, it is determined whether or not the characteristic value determined from the fuel sedan number determined in S 101 and the altitude determined in S 102 belongs to the above-described combustion deterioration range of FIG. If an affirmative determination is made in S103, the ECU 17 proceeds to S104.

In S 104, the ECU 17 activates the glow plug 5. In addition, when the glow plug 5 is operated, if the energization is continuously performed on the glow plug 5, there is a possibility that the power consumption is increased or the glow plug 5 is deteriorated. For this reason, it is preferable that the ECU 17 intermittently energizes the glow plug 5 and changes the ratio of the energization time and the non-energization time at that time according to the engine operating state.

Specifically, the ECU 17 is energized when the internal combustion engine 1 is in a low rotation / low load operation state, and the energization time is longer than the non-energization time, and is energized when the internal combustion engine 1 is in a high rotation / high load operation state. The power supply to the glow plug 5 may be controlled so that the time is shorter than the non-energization time.

When the energization control of the glow plug 5 is performed in this manner, the increase in power consumption and degradation of the glow plug 5 due to the combustion deterioration suppression control can be minimized. If a negative determination is made in S 103, the ECU 17 proceeds to S 105, and the execution of this routine is terminated without operating the glow plug 5.

In this way, the control means according to the present invention is realized by the ECU 17 executing S103 to S105. Therefore, according to the control system for an internal combustion engine according to the present embodiment, it is possible to suppress the deterioration of fuel combustion when the deterioration condition of combustion due to the altitude or the fuel sedan number is satisfied. As a result, the amount of white smoke emitted from the internal combustion engine 1 can be kept below the white smoke limit value.

In the present embodiment, an example in which the glow plug 5 is operated when the combustion deterioration condition due to the altitude and the fuel sedan number is satisfied is described. However, the pressure of the intake air compressed by the turbocharger 8 (excessive pressure) The smoke emission of the internal combustion engine 1 also increases when the (supply pressure) becomes lower than the target boost pressure. This is because when the boost pressure of the intake air becomes lower than the target boost pressure, the compression end temperature decreases and the amount of oxygen in the cylinder 2 becomes too small, resulting in an increase in the amount of unburned fuel.

Therefore, the ECU 17 determines whether the boost pressure (measured value of the intake pressure sensor 20) is lower than the target boost pressure in addition to the case where the characteristic value determined from the altitude and the fuel cetane number belongs to the combustion deterioration range. Plug 5 may be actuated.

Specifically, the ECU 17 determines whether or not the measured value of the intake pressure sensor 20 is lower than the target boost pressure when a negative determination is made in S 103 of the above-described combustion deterioration suppression control routine (see FIG. 4). To do. If it is determined that the measured value of the intake pressure sensor 20 is lower than the target boost pressure, the ECU 17 may operate the glow plug 5.

When the glow plug 5 is operated in this way, in addition to an increase in altitude and a decrease in fuel cetane number, combustion deterioration due to a decrease in supercharging pressure is also suppressed. As a result, the emission of white smoke due to the lower supercharging pressure is also suppressed.

In this embodiment, the altitude of the place where the internal combustion engine 1 is used and the internal combustion engine 1 In the above example, both of the fuel selenic value and the fuel sedan number are detected, but only one of them may be detected. In that case, the ECU 17 may operate the glow plug 5 on condition that the detected value belongs to the combustion deterioration range.

Claims

The scope of the claims

1. In an internal combustion engine control system with a glow plug,

First detection means for detecting an altitude at which the internal combustion engine is used;

Control means for operating the glow plug when the detection value of the first detection means belongs to a predetermined combustion deterioration range;

An internal combustion engine control system comprising:

2. In an internal combustion engine control system with a glow plug,

Second detection means for detecting a cetane number of fuel used by the internal combustion engine; control means for operating a glow plug when a detection value of the second detection means belongs to a predetermined combustion deterioration range;

An internal combustion engine control system comprising:

3. In an internal combustion engine control system with a glow plug,

A second detecting means for detecting a fuel titration value used by the internal combustion engine; and a glow plug when the detected value of the first detecting means and Z or the second detecting means falls within a predetermined combustion deterioration range. Control means to be activated;

An internal combustion engine control system comprising:

4. The control system for an internal combustion engine according to claim 1 or 3, wherein the combustion deterioration range is a range in which a detection value of the first detection means is not less than a predetermined altitude.

5. The combustion deterioration range according to claim 2 or 3, wherein the combustion deterioration range is detected by the second detection means. A control system for an internal combustion engine, characterized in that the value falls within a predetermined sein value.

6. The combustion deterioration range according to claim 3, wherein the range in which the detection value of the first detection means is equal to or higher than a predetermined altitude, and / or the range in which the detection value of the second detection means is equal to or lower than a predetermined set value. An internal combustion engine control system.

7. The supercharger for compressing intake air of the internal combustion engine according to any one of claims 1, 3, and 4,

A third detecting means for detecting a supercharging pressure of the intake air compressed by the supercharger;

The combustion deterioration range further includes a range in which the detection value of the third detection means is less than a target boost pressure,

The control means operates a glow plug when either one or both of the detection value of the first detection means and the detection value of the third detection means belong to the combustion deterioration range. Control system.

8. The supercharger for compressing intake air of the internal combustion engine according to any one of claims 2, 3, and 5,

The control means operates the glow plug when one or both of the detection value of the second detection means and the detection value of the third detection means belong to the combustion deterioration range. Control system for internal combustion engine characterized by

9. The turbocharger according to claim 3 or 6, further comprising: a supercharger that compresses the intake air of the internal combustion engine; and third detection means that detects a supercharging pressure of the intake air compressed by the supercharger,

The control means includes a glow plug when one or more of the detection value of the first detection means, the detection value of the second detection means, and the detection value of the third detection means belongs to the combustion deterioration range. An internal combustion engine control system which is operated.