JP5692135B2 - In-cylinder moisture detection device for internal combustion engine, control device for internal combustion engine - Google Patents

Description

  The present invention relates to an in-cylinder moisture detection device for an internal combustion engine and a control device for the internal combustion engine.

  2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-299631, a control device for an internal combustion engine that performs control for suppressing the generation of condensed water when moisture is generated in the exhaust pipe is known. ing. The exhaust gas contains water vapor generated by a combustion reaction. For example, if the temperature of the exhaust pipe is low immediately after starting the internal combustion engine, the exhaust gas containing water vapor is cooled in the exhaust pipe. As a result, the water vapor in the exhaust gas is condensed to produce liquid water. That is, condensed water is generated. In the control device for an internal combustion engine according to the above publication, such condensed water suppression control for suppressing condensed water can be executed. As a specific example of the condensed water suppression control, the steam is contained from the idle cylinder during fuel cut. A small amount of high-temperature air is discharged to the exhaust pipe (paragraph 0009 etc. of the publication).

JP 2009-299631 A JP 2009-235908 A JP 2009-185721 A JP 2009-235909 A

  There is also a concern that liquid water (specifically, condensate as in the above publication) may enter the cylinder and cause harmful effects. Typical examples of the harmful effects concerned include corrosion of the fuel injection valve (cylinder fuel injector) and corrosion of the spark plug. Some measures should be taken against the water in the cylinder. However, although the above publication considers measures against water in the exhaust pipe, detection of water in the cylinder has not been studied.

  By the way, in recent years, the technical development of in-cylinder pressure sensors has been remarkable. According to the in-cylinder pressure sensor, the combustion pressure of the cylinder can be detected directly and accurately. The in-cylinder pressure sensor has been studied for application not only to detection of combustion pressure but also to detection of various combustion parameters. As a result of intensive studies, the inventor of the present application has found a novel technique capable of detecting water in a cylinder using an in-cylinder pressure sensor.

One object of the present invention is to provide an in-cylinder moisture detecting device for an internal combustion engine capable of detecting water in a cylinder.
Another object of the present invention is to provide a control device for an internal combustion engine that can execute appropriate control in accordance with detection of water in the cylinder.

In order to achieve the above object, a first invention is an in-cylinder moisture detection device for an internal combustion engine,
The internal combustion engine includes at least one cylinder, an intake valve provided in an intake port of the cylinder, a fuel injection valve for injecting fuel into the cylinder, and an in-cylinder pressure sensor provided in the cylinder. And
Obtaining means for obtaining an output from the in-cylinder pressure sensor;
Calculating means for calculating a heat release rate of the cylinder based on an output of the in-cylinder pressure sensor;
Detecting means for detecting water in the cylinder based on a magnitude of the heat generation rate in a period from when the intake valve is closed to when the fuel injection by the fuel injection valve is started;
It is characterized by providing.

According to a second invention, in the first invention,
If the magnitude of the heat generation rate during a period from the closing of the intake valve of the cylinder to the start of fuel injection falls below a predetermined value, the detection means indicates that a predetermined amount or more of water exists in the cylinder. It is characterized by including the means to detect.

According to a third invention, in the first or second invention,
The detection means detects water in the cylinder based on whether or not the heat generation rate during the period from when the intake valve of the cylinder is closed to when fuel injection starts indicates a negative heat generation rate. It is characterized by including.

A fourth aspect of the invention is a control device for an internal combustion engine in order to achieve the other object,
The internal combustion engine includes at least one cylinder, an intake valve provided in an intake port of the cylinder, a fuel injection valve for injecting fuel into the cylinder, and an in-cylinder pressure sensor provided in the cylinder. And
Obtaining means for obtaining an output from the in-cylinder pressure sensor;
Calculating means for calculating a heat release rate of the cylinder based on an output of the in-cylinder pressure sensor;
Detecting means for detecting water in the cylinder based on a magnitude of the heat generation rate in a period from when the intake valve is closed to when the fuel injection by the fuel injection valve is started;
When the water is detected by the detection means, control means for executing condensed water suppression control,
It is characterized by providing.

A fifth invention is the fourth invention,
The internal combustion engine includes at least one of an EGR system and an intake heater;
The condensed water suppression control is at least one of control for reducing the EGR amount by the EGR system, control for relatively increasing the EGR gas temperature by the EGR system, and control for operating the intake heater. It is characterized by including.

A sixth invention is an in-cylinder moisture detecting device for an internal combustion engine,
The internal combustion engine includes at least one cylinder, an intake valve provided in an intake port of the cylinder, at least one of a port injection valve and an in-cylinder injection valve provided for the cylinder, and an ignition provided in the cylinder A plug and an in-cylinder pressure sensor provided in the cylinder;
Obtaining means for obtaining an output from the in-cylinder pressure sensor;
Calculating means for calculating a heat release rate of the cylinder based on an output of the in-cylinder pressure sensor;
Detecting means for detecting water in the cylinder based on the magnitude of the heat generation rate in a period from when the intake valve is closed until ignition timing of the spark plug;
It is characterized by providing.

A seventh aspect of the invention is a control device for an internal combustion engine,
The internal combustion engine includes at least one cylinder, an intake valve provided in an intake port of the cylinder, at least one of a port injection valve and an in-cylinder injection valve provided for the cylinder, and an ignition provided in the cylinder A plug and an in-cylinder pressure sensor provided in the cylinder;
Obtaining means for obtaining an output from the in-cylinder pressure sensor;
Calculating means for calculating a heat release rate of the cylinder based on an output of the in-cylinder pressure sensor;
Detecting means for detecting water in the cylinder based on the magnitude of the heat generation rate in a period from when the intake valve is closed until ignition timing of the spark plug;
When the water is detected by the detection means, control means for executing condensed water suppression control,
It is characterized by providing.

  According to the first invention, the water in the cylinder can be detected using the in-cylinder pressure sensor.

  According to the second invention, the amount of water in the cylinder can be detected by comparing the magnitude of the heat generation rate with a predetermined value.

  According to the third invention, water in the cylinder can be detected based on whether or not the heat generation rate shows a negative heat generation rate.

  According to the fourth aspect of the invention, the condensed water suppression control can be executed in response to detection of water in the cylinder.

  According to the fifth aspect of the present invention, the EGR system and the intake heater can be controlled to suppress the condensed water, and the water in the cylinder can be reduced.

  According to the sixth aspect, the water in the cylinder can be detected using the in-cylinder pressure sensor.

  According to the seventh aspect, the condensed water suppression control can be executed in response to the detection of water in the cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram for explaining a configuration of an in-cylinder moisture detection device for an internal combustion engine and an internal combustion engine control device according to an embodiment of the present invention, together with the internal combustion engine system to which this is applied. It is a figure for demonstrating the control action in the in-cylinder moisture detection apparatus of the internal combustion engine which concerns on embodiment of this invention, and the control apparatus of an internal combustion engine. It is a figure which shows a mode that a negative heat release rate generate | occur | produces. 4 is a flowchart of a routine executed by the ECU in the in-cylinder moisture detection device for an internal combustion engine and the control device for the internal combustion engine according to the embodiment of the present invention.

Embodiment.
[Configuration of the embodiment]
FIG. 1 is a block diagram for explaining the configuration of an in-cylinder moisture detecting device and a control device for an internal combustion engine according to an embodiment of the present invention, together with the internal combustion engine system to which this is applied. The internal combustion engine system of the present embodiment includes an engine 10. Each cylinder of the engine 10 is provided with a piston, and a combustion chamber is formed by the piston. The piston is connected to a crankshaft that is an output shaft of the engine 10. The engine 10 is provided with a plurality of cylinders. In many cases, the vehicle-mounted engine 10 includes a plurality of cylinders, and the engine 10 also includes a plurality of cylinders.

  Each cylinder is provided with an intake valve that opens and closes the intake port with respect to the cylinder. The cylinder also includes a fuel injection valve (in-cylinder injection valve) 16 that directly injects fuel into the cylinder. The cylinder communicates with the exhaust port, and an exhaust valve that opens and closes the exhaust port with respect to the inside of the cylinder is provided. The engine 10 also includes an intake heater 20.

  The engine 10 includes an EGR system 18 that performs exhaust gas recirculation. Specifically, the EGR system 18 includes an EGR passage that connects the exhaust passage and the intake passage, and an EGR valve and an EGR cooler that are provided in the EGR passage. In the present embodiment, a bypass passage that bypasses the EGR cooler is provided in the EGR passage, and a bypass valve that opens and closes the bypass passage is also provided.

  Furthermore, the system of the present embodiment includes a sensor system including a crank angle sensor 12 and an in-cylinder pressure sensor 14 and an ECU 50 (Electronic Control Unit) that controls the operating state of the engine 10. First, the sensor system will be described. The crank angle sensor 12 outputs a signal synchronized with the rotation of the crankshaft, and the ECU 50 detects the engine speed (engine speed) and the crank angle based on this output. can do. The cylinder volume determined by the crank angle can also be calculated. In the present embodiment, ECU 50 detects the closing timing of the intake valve based on the crank angle. The in-cylinder pressure sensor 14 can detect the combustion pressure in the cylinder. The ECU 50 can calculate a value for each crank angle of the combustion pressure (cylinder pressure) of the engine 10 based on the output signal of the cylinder pressure sensor 14.

  The sensor system includes various sensors necessary for controlling the vehicle and the engine 10 (for example, a water temperature sensor for detecting the temperature of the engine 10 coolant, an accelerator opening sensor for detecting the accelerator opening, and a rotation angle of the camshaft). Cam angle sensors and the like), and these sensors are connected to the input side of the ECU 50. Various actuators including the fuel injection valve 16 are connected to the output side of the ECU 50. Then, the ECU 50 detects operation information of the engine 10 by a sensor system, and performs operation control by driving each actuator based on the detection result. The ECU 50 is also connected to the EGR valve and bypass valve in the EGR system 18 and the intake heater 20. The ECU 50 executes a control program for controlling them according to the operating state of the engine 10 and controls its opening, opening / closing, and on / off.

  The ECU 50 includes a heat generation rate calculation unit 52 and a condensed water suppression control unit 54. The heat generation rate calculation unit 52 calculates the heat generation rate of the cylinder to which the in-cylinder pressure sensor 14 is attached based on the output of the in-cylinder pressure sensor 14. The heat generation rate may be calculated using various known calculation methods.

The condensed water suppression control unit 54 executes the following controls (1) to (3) as “condensed water suppression control” as will be described in the flowchart of FIG.
(1) Control for reducing the amount of EGR by the EGR system 18. That is, control for reducing the opening of the EGR valve.
(2) Control for relatively increasing the EGR gas temperature by the EGR system 18. That is, control is performed so that the EGR gas flows through the bypass passage by opening the bypass valve so that the EGR gas bypasses the EGR cooler.
(3) Control for operating the intake heater 20.

[Control operation of the embodiment]
Intrusion of condensed water into the cylinder of the engine 10 may cause a problem of nozzle corrosion of the fuel injection valve 16. Therefore, it is desirable to control the engine 10 so as to suppress the generation of condensed water. Therefore, in the present embodiment, the presence or absence of liquid water (condensed water) in the cylinder is detected by the following method.

  FIG. 2 is a diagram for explaining a control operation in the in-cylinder moisture detection device for an internal combustion engine and the control device for the internal combustion engine according to the embodiment of the present invention. FIG. 2 is a graph showing a heat generation rate and a fuel injection rate according to the crank angle. The horizontal axis represents the crank angle, and the vertical axis represents the heat generation rate (upper stage in FIG. 2) or the fuel injection rate (lower stage in FIG. 2).

In the embodiment, the water in the cylinder is detected using the value of the heat generation rate in the period “from when the intake valve is closed until the start of fuel injection of the fuel injection valve 16”. When liquid water enters the cylinder, the water evaporates during the compression stroke after the intake valve is closed. Then, a negative heat generation rate is calculated due to the influence of latent heat of vaporization. That is, the value of the heat generation rate is calculated to be lower than when there is no influence of the latent heat of vaporization.
That is, when heat escapes from the cylinder for some reason, the heat generation rate becomes a negative value. Typical is the negative heat generation rate due to the latent heat of vaporization of the fuel injected into the cylinder. It is considered that basically the same phenomenon occurs when condensed water enters the cylinder and evaporates during the compression stroke. In addition, FIG. 3 is a figure which shows an example of a mode that a negative heat release rate generate | occur | produces.
On the other hand, when fuel injection starts, it is difficult to distinguish between a negative heat generation rate due to fuel evaporation and a negative heat generation rate due to water evaporation.
Therefore, in the present embodiment, as a preferred embodiment, as shown in FIG. 2, the heat generation rate during the period “after the intake valve is closed and before the fuel injection of the fuel injection valve 16 is started during the compression stroke”. The value of is used. By using the value of this period, it is possible to accurately detect liquid water in the cylinder based on the magnitude of the heat generation rate.

  Note that the presence or absence of condensed water is affected by the environment in which the engine 10 is operated, specifically, humidity, temperature, atmospheric pressure, fuel H / C ratio, and the like. It also depends on the local wall temperature of the engine 10 and the like. It is not easy to perform control taking all of these into consideration, and it is inefficient because it is necessary to keep a large safety merge even if the adaptation is performed. In this regard, according to the present embodiment, it is possible to stably detect the water in the cylinder based on the output of the in-cylinder pressure sensor 14 while avoiding the negative effects of these methods.

[Specific processing of the embodiment]
FIG. 4 is a flowchart of a routine executed by the ECU 50 in the in-cylinder moisture detection device for an internal combustion engine and the control device for the internal combustion engine according to the embodiment of the present invention. This routine is executed while the engine 10 is operating.

In the routine of FIG. 4, first, the ECU 50 executes a determination process for determining whether or not the heat generation rate in a predetermined range is below a predetermined value (step S100). The predetermined range is the “determination range” shown in FIG. 2 and is a period from when the intake valve is closed until fuel injection is started.
If the condition in step S100 is not satisfied (NO), the current routine is terminated.

  Specifically, in step S100, it is determined whether or not the magnitude of the heat generation rate in the “determination range” in FIG. 2 is so large that it falls below “−ΔQ”. If it can be determined that the heat generation rate is negative, absolute values may be simply compared. This “−ΔQ” is set to a value that can determine whether the heat generation rate can be determined to be lower than “heat escape to the engine wall surface” or not. That is, taking into account the escape of heat to the engine wall surface, the magnitude of “−ΔQ” is determined to such an extent that the negative heat generation rate can be considered to be due to the latent heat of vaporization of the condensed water. By comparing the heat generation rate within the determination range with “−ΔQ”, the water in the cylinder of the engine 10 can be detected with high accuracy. Note that the value of “−ΔQ” may be given to the ECU 50 as a map according to the driving conditions and the like.

  If the condition in step S100 is satisfied (YES), the ECU 50 next executes a process for determining that there is condensed water in the cylinder (step S102). For example, a process such as turning on a condensed water generation flag.

  Next, the ECU 50 performs condensed water suppression control (step S104). In this step, as described above, the condensed water suppression control unit 54 executes the controls (1) to (3) described above as “condensed water suppression control”. Thereby, generation | occurrence | production of condensed water can be suppressed. Thereafter, the process returns.

As shown in FIG. 2, when the “magnification of heat generation rate during the period from when the intake valve is closed until the start of fuel injection” is below a predetermined value “−ΔQ”, a predetermined amount or more in the cylinder Detection of the presence of water may be performed. That is, the correlation between the value of the negative heat generation rate and the amount of water causing the latent heat of vaporization can be used.
Note that “the magnitude of the heat generation rate during the period from when the intake valve is closed until the start of fuel injection” may be determined as to whether it is below “−ΔQ” over one point or several points of the crank angle. Further, the average value of the heat generation rate within the determination range and the maximum value on the minus side of the heat generation rate within the determination range may be compared with a predetermined value. Further, the integrated value of the heat generation rate within the determination range may be compared with other predetermined values. By using these various determination methods singly or in combination, it may be evaluated whether the magnitude of the negative heat generation rate within the determination range is affected by the latent heat of vaporization of water.

  Although not particularly specified in the present embodiment, the present invention can be used in a compression ignition engine and a spark ignition engine. In the case of a spark ignition type engine, the present invention can be applied to an engine including an in-cylinder direct injection injector or an engine including a dual injection system capable of performing both port injection and in-cylinder injection. This is because the in-cylinder direct injection injectors of those engines can perform the same role as the fuel injection valve 16 of the engine 10.

  Further, in a spark ignition type engine, there is a concern about corrosion of the spark plug due to water intrusion into the cylinder. Therefore, as a modification of the embodiment, in the case of a spark ignition type engine, water detection in the cylinder may be performed based on “the magnitude of the heat generation rate during the period from when the intake valve is closed until ignition”. Specifically, the heat generation rate may be compared with a predetermined value. From the viewpoint of dealing with the concern of spark plug corrosion, the present invention may be applied to a spark ignition engine having only port injection. In this case, in the above-described “condensed water suppression control”, “control operation according to the embodiment”, and “specific processing of the embodiment”, fuel injection is performed after the intake valve is closed as a predetermined range. The “period until the start” may be read as “the period from when the intake valve is closed until ignition”, and the accompanying deformation may be performed. For example, the predetermined range in the determination process of step S100 of the flowchart is changed, or the value of ΔQ used for comparison determination is modified to an appropriate value by experiment or the like.

DESCRIPTION OF SYMBOLS 10 Engine 12 Crank angle sensor 14 In-cylinder pressure sensor 16 Fuel injection valve 18 EGR system 20 Intake heater 50 ECU (Electronic Control Unit)
52 Heat Release Rate Calculation Unit 54 Condensed Water Suppression Control Unit

Claims (7)

An in-cylinder moisture detection device for an internal combustion engine,
The internal combustion engine includes at least one cylinder, an intake valve provided in an intake port of the cylinder, a fuel injection valve for injecting fuel into the cylinder, and an in-cylinder pressure sensor provided in the cylinder. And
Obtaining means for obtaining an output from the in-cylinder pressure sensor;
Calculating means for calculating a heat release rate of the cylinder based on an output of the in-cylinder pressure sensor;
Detecting means for detecting water in the cylinder based on a magnitude of the heat generation rate in a period from when the intake valve is closed to when the fuel injection by the fuel injection valve is started;
An in-cylinder moisture detection device for an internal combustion engine, comprising:   If the magnitude of the heat generation rate during a period from the closing of the intake valve of the cylinder to the start of fuel injection falls below a predetermined value, the detection means indicates that a predetermined amount or more of water exists in the cylinder. The in-cylinder moisture detecting device for an internal combustion engine according to claim 1, further comprising means for detecting   The detection means detects water in the cylinder based on whether or not the heat generation rate during the period from when the intake valve of the cylinder is closed to when fuel injection starts indicates a negative heat generation rate. The in-cylinder moisture detecting device for an internal combustion engine according to claim 1 or 2, characterized by comprising: A control device for an internal combustion engine,
The internal combustion engine includes at least one cylinder, an intake valve provided in an intake port of the cylinder, a fuel injection valve for injecting fuel into the cylinder, and an in-cylinder pressure sensor provided in the cylinder. And
Obtaining means for obtaining an output from the in-cylinder pressure sensor;
Calculating means for calculating a heat release rate of the cylinder based on an output of the in-cylinder pressure sensor;
Detecting means for detecting water in the cylinder based on a magnitude of the heat generation rate in a period from when the intake valve is closed to when the fuel injection by the fuel injection valve is started;
When the water is detected by the detection means, control means for executing condensed water suppression control,
A control device for an internal combustion engine, comprising: The internal combustion engine includes at least one of an EGR system and an intake heater;
The condensed water suppression control is at least one of control for reducing the EGR amount by the EGR system, control for relatively increasing the EGR gas temperature by the EGR system, and control for operating the intake heater. The control apparatus for an internal combustion engine according to claim 4, comprising: An in-cylinder moisture detection device for an internal combustion engine,
The internal combustion engine includes at least one cylinder, an intake valve provided in an intake port of the cylinder, at least one of a port injection valve and an in-cylinder injection valve provided for the cylinder, and an ignition provided in the cylinder A plug and an in-cylinder pressure sensor provided in the cylinder;
Obtaining means for obtaining an output from the in-cylinder pressure sensor;
Calculating means for calculating a heat release rate of the cylinder based on an output of the in-cylinder pressure sensor;
Detecting means for detecting water in the cylinder based on the magnitude of the heat generation rate in a period from when the intake valve is closed until ignition timing of the spark plug;
An in-cylinder moisture detection device for an internal combustion engine, comprising: A control device for an internal combustion engine,
The internal combustion engine includes at least one cylinder, an intake valve provided in an intake port of the cylinder, at least one of a port injection valve and an in-cylinder injection valve provided for the cylinder, and an ignition provided in the cylinder A plug and an in-cylinder pressure sensor provided in the cylinder;
Obtaining means for obtaining an output from the in-cylinder pressure sensor;
Calculating means for calculating a heat release rate of the cylinder based on an output of the in-cylinder pressure sensor;
Detecting means for detecting water in the cylinder based on the magnitude of the heat generation rate in a period from when the intake valve is closed until ignition timing of the spark plug;
When the water is detected by the detection means, control means for executing condensed water suppression control,
A control device for an internal combustion engine, comprising:

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