JP2014098360A - Abnormal combustion determination device of internal combustion engine and control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately determine occurrence of abnormal combustion caused by commingling of lubricant with fuel of an internal combustion engine or to prevent the occurrence of abnormal combustion caused by the commingling of the lubricant with the fuel of the internal combustion engine.SOLUTION: An abnormal combustion determination device of an internal combustion engine comprises: hydraulic pressure detection means which detects pressure of lubricant of the internal combustion engine; determination means which determines occurrence of abnormal combustion when the pressure of the lubricant detected by the hydraulic pressure detection means is lower than a predetermined range including a reference hydraulic pressure, a reference value of the pressure of the lubricant of the internal combustion engine; and reference hydraulic pressure setting means which sets the pressure of the lubricant detected by the hydraulic pressure detection means as the reference hydraulic pressure for succeeding determination when the pressure of the lubricant detected by the hydraulic pressure detection means is higher than the predetermined range.

Description

  The present invention relates to an abnormal combustion determination device for an internal combustion engine and a control device for the internal combustion engine.

  In a spark ignition type internal combustion engine, in order to suppress abnormal combustion (preignition) where combustion starts before spark ignition, when the occurrence of preignition is detected or predicted, the fuel injection timing is determined as the operating condition of the internal combustion engine. It is known that the reference fuel injection timing is set on the retard side with respect to the reference fuel injection timing (see, for example, Patent Document 1).

  In this technique, the vibration intensity and the vibration generation timing of the vibration generated in the internal combustion engine main body are detected, and the vibration generation timing is advanced from the ignition timing when the vibration intensity exceeds a predetermined allowable range. When it is on the side, the occurrence of pre-ignition is detected. Moreover, the occurrence of pre-ignition is predicted when the engine operation in the specific operation region continues for a predetermined time or more. Furthermore, the occurrence of pre-ignition is predicted when the engine is operating in a specific operation region and the engine coolant temperature is equal to or higher than a predetermined temperature. Further, the occurrence of pre-ignition is predicted when the engine is operating in a specific operation region and the wall temperature of the combustion chamber is equal to or higher than a predetermined temperature.

  Incidentally, abnormal combustion occurs due to various other causes. Here, it has been found that when the fuel is mixed with the lubricating oil of the internal combustion engine, pre-ignition easily occurs. In the following, the mixing of the fuel with the lubricating oil is referred to as “oil dilution”, and the ratio of the amount of fuel mixed in the lubricating oil to the amount of lubricating oil is referred to as the oil dilution ratio. And if the preignition which generate | occur | produces by oil dilution can be suppressed, durability of an internal combustion engine can be improved.

JP 2002-339780 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to determine the occurrence of abnormal combustion due to the mixing of fuel with the lubricating oil of an internal combustion engine with higher accuracy, or the internal combustion engine. It is to suppress the occurrence of abnormal combustion due to the fuel mixed with the engine lubricating oil.

In order to achieve the above object, the present invention provides:
Oil pressure detection means for detecting the pressure of the lubricating oil of the internal combustion engine;
Determining means for determining that abnormal combustion occurs when the pressure of the lubricating oil detected by the oil pressure detecting means is lower than a predetermined range including a reference oil pressure that is a reference value of the lubricating oil pressure of the internal combustion engine;
In an abnormal combustion determination device for an internal combustion engine comprising:
When the pressure of the lubricating oil detected by the hydraulic pressure detection means is higher than the predetermined range, the reference hydraulic pressure that sets the pressure of the lubricating oil detected by the hydraulic pressure detection means at that time as the reference hydraulic pressure thereafter Setting means is provided.

Here, the higher the oil dilution rate, the lower the pressure detected by the oil pressure detection means, and the lower the oil dilution rate, the higher the pressure detected by the oil pressure detection means. That is, there is a correlation between the oil dilution rate and the oil pressure. The reference oil pressure is updated every time the pressure of the lubricating oil detected by the oil pressure detecting means becomes higher than a predetermined range. Note that the initial value of the reference hydraulic pressure can be the pressure of the lubricating oil when the internal combustion engine is started or the pressure of the lubricating oil when the internal combustion engine is warmed up.

  The predetermined range is a range of pressure including the reference oil pressure, and is a range in which the pressure detected by the oil pressure detecting means can be considered as not changing from the reference oil pressure. This predetermined range may be determined in consideration of pressure errors and pressure fluctuations detected by the hydraulic pressure detection means. The predetermined range may be a range in which a change in pressure does not affect the occurrence of abnormal combustion.

  When the pressure of the lubricating oil detected by the oil pressure detecting means is higher than the predetermined range, it can be said that the oil dilution rate at that time is lower than when the reference oil pressure is set. That is, it can be said that the oil dilution is reduced as compared with the case where the reference oil pressure is set. By using the pressure detected at this time as the reference oil pressure, the oil pressure detected thereafter is compared with a predetermined range including the reference oil pressure, so that the reference oil pressure is set. It can be determined whether the oil dilution rate is rising or falling. When the oil dilution rate increases from the time when the reference oil pressure is set, the detected oil pressure is lower than the predetermined range, and at this time, it can be determined that abnormal combustion occurs.

  Further, as described above, when the oil dilution rate decreases, the hydraulic pressure increases, so that the lubricating oil pressure detected by the hydraulic pressure detection means becomes higher than a predetermined range including the reference hydraulic pressure. In this case, the oil dilution may be eliminated, but the oil dilution rate may still be high. Therefore, even if the oil dilution rate decreases, there is still a possibility that abnormal combustion may occur.

  On the other hand, when the pressure of the lubricating oil detected by the oil pressure detecting means becomes higher than the reference oil pressure, the pressure of the lubricating oil detected by the oil pressure detecting means at that time is used as the reference oil pressure thereafter. Thus, a higher pressure can be set as the reference hydraulic pressure. Then, when the oil dilution rate is increased next time, that is, when the hydraulic pressure is decreased, it can be immediately determined that abnormal combustion occurs. In this way, by changing the reference oil pressure in such a direction that it is easy to determine that abnormal combustion occurs when the oil pressure decreases, occurrence of abnormal combustion can be determined with higher accuracy. In addition, by using the actually detected pressure as the reference oil pressure, it is possible to cope with individual differences in the internal combustion engine, sensors, etc., changes over time, or changes in operating conditions of the internal combustion engine. In other words, if the reference hydraulic pressure is set to a fixed value, it is impossible to cope with these changes, and there is a possibility that the determination accuracy of occurrence of abnormal combustion may be reduced. be able to.

Moreover, in order to achieve the above-mentioned problem, the present invention
Oil pressure detection means for detecting the pressure of the lubricating oil of the internal combustion engine;
When the pressure of the lubricating oil detected by the hydraulic pressure detecting means is lower than a predetermined range including a reference hydraulic pressure that is a reference value of the pressure of the lubricating oil of the internal combustion engine, control is performed to suppress the occurrence of abnormal combustion. Control means;
An internal combustion engine control apparatus comprising:
When the pressure of the lubricating oil detected by the hydraulic pressure detection means is higher than the predetermined range, the reference hydraulic pressure that sets the pressure of the lubricating oil detected by the hydraulic pressure detection means at that time as the reference hydraulic pressure thereafter Setting means is provided.

The control that suppresses the occurrence of abnormal combustion is control that makes it difficult for abnormal combustion to occur, and may be a control that changes a physical quantity correlated with the occurrence of abnormal combustion in a direction that does not cause abnormal combustion. . Then, this control is performed when the pressure of the lubricating oil detected by the hydraulic pressure detection means is lower than a predetermined range, thereby suppressing the occurrence of abnormal combustion.

  Then, when the pressure of the lubricating oil detected by the hydraulic pressure detection means becomes higher than the reference hydraulic pressure, the pressure of the lubricating oil detected by the hydraulic pressure detection means at that time is used as the subsequent reference hydraulic pressure. The higher pressure can be used as the reference hydraulic pressure. Then, when the oil dilution rate is increased next time, that is, when the hydraulic pressure is decreased, control for suppressing the occurrence of abnormal combustion can be performed immediately. In this way, the occurrence of abnormal combustion can be suppressed by changing the reference oil pressure in such a direction that the control for suppressing the occurrence of abnormal combustion is easily performed when the oil pressure decreases. In addition, by using the actually detected pressure as the reference oil pressure, it is possible to cope with individual differences in the internal combustion engine, sensors, etc., changes over time, or changes in operating conditions of the internal combustion engine. That is, if the reference hydraulic pressure is a fixed value, it is not possible to cope with these changes and abnormal combustion may occur, but the occurrence of abnormal combustion can be suppressed by updating the reference hydraulic pressure.

  According to the present invention, it is possible to determine the occurrence of abnormal combustion due to mixing of fuel with lubricating oil of an internal combustion engine with higher accuracy. In addition, the occurrence of abnormal combustion due to the mixing of fuel with the lubricating oil of the internal combustion engine can be suppressed.

It is a figure which shows schematic structure of the internal combustion engine which concerns on an Example. It is the figure which showed the relationship between an engine speed, an engine torque, and the driving | running area | region (pre-ignition area | region) where pre-ignition is easy to generate | occur | produce. It is the flowchart which showed the control flow of the internal combustion engine which concerns on an Example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.

Example 1
FIG. 1 is a diagram illustrating a schematic configuration of an internal combustion engine according to the present embodiment. An internal combustion engine 1 shown in FIG. 1 is a spark ignition type gasoline engine.

  The internal combustion engine 1 is provided with a fuel injection valve 2 for injecting fuel into the cylinder and an ignition plug 3 for generating electric sparks. In addition, although the fuel injection valve 2 which concerns on a present Example injects a fuel in a cylinder, it may replace with this and may inject a fuel in the intake port or the intake pipe of the internal combustion engine 1.

  Further, the internal combustion engine 1 includes a hydraulic pressure sensor 4 that detects the pressure (hydraulic pressure) of the lubricating oil discharged from the pump, and a crank position sensor 5 that detects the rotational speed (engine rotational speed) of the output shaft of the internal combustion engine 1. It is attached. In the present embodiment, the hydraulic sensor 4 corresponds to the hydraulic pressure detection means in the present invention.

  The internal combustion engine 1 is also provided with an ECU 10 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 10 controls the internal combustion engine 1 in accordance with the operating conditions of the internal combustion engine 1 and the driver's request.

In addition to the above sensors, the ECU 10 is connected to an accelerator opening sensor 7 that outputs an electrical signal corresponding to the amount of depression of the accelerator pedal 6 by the driver and detects the engine load via electrical wiring. An output signal of the sensor is input to the ECU 10. On the other hand, the fuel injection valve 2 and the spark plug 3 are connected to the ECU 10 via electric wiring, and these devices are controlled by the ECU 10.

  Then, the ECU 10 detects a change in the oil dilution rate based on the hydraulic pressure detected by the hydraulic pressure sensor 4, and determines that pre-ignition (abnormal combustion) occurs when the oil dilution rate becomes high, and also generates pre-ignition. Implement control to suppress this. In the present embodiment, the load of the internal combustion engine 1 is limited as control for suppressing the occurrence of pre-ignition, but the occurrence of pre-ignition may be suppressed by performing other well-known controls.

  Here, when the oil dilution rate increases, the hydraulic pressure decreases accordingly. That is, since there is a correlation between the oil dilution rate and the oil pressure, it can be determined whether the oil dilution rate is rising or falling based on the transition of the oil pressure. For example, when the oil pressure increases during a predetermined period, it can be determined that the oil dilution rate has decreased, and when the oil pressure has decreased during a predetermined period, it can be determined that the oil dilution rate has increased.

  Here, FIG. 2 is a diagram showing the relationship between the engine speed, the engine torque, and the operation region in which pre-ignition is likely to occur (hereinafter referred to as pre-ignition region). As shown in FIG. 2, the pre-ignition region is a low-rotation and high-load region that is an operation region where the engine speed is relatively low and the engine torque is relatively high. On the other hand, oil dilution is likely to occur when the temperature of the internal combustion engine 1 is low or when the load is low. When the internal combustion engine 1 is operated in the pre-ignition region when oil dilution is occurring, pre-ignition can occur.

  If the internal combustion engine 1 has been warmed up, the fuel is removed from the lubricating oil by operating the internal combustion engine 1 outside the pre-ignition region. Thereby, generation | occurrence | production of preignition can be suppressed. As the oil dilution rate decreases, the hydraulic pressure increases.

  In this embodiment, the hydraulic pressure detected by the hydraulic pressure sensor 4 (hereinafter referred to as actual hydraulic pressure) is compared with a predetermined range including a reference value of hydraulic pressure (hereinafter referred to as reference hydraulic pressure). Then, when the actual oil pressure is lower than the predetermined range, it is determined that the oil pressure has decreased due to an increase in the oil dilution rate. At this time, it is determined that pre-ignition occurs, and control is performed to suppress the occurrence of pre-ignition. On the other hand, when the actual oil pressure is higher than a predetermined range including the reference oil pressure, it is determined that the oil pressure has increased due to a decrease in the oil dilution rate. At this time, the reference hydraulic pressure is updated.

  The initial value of the reference oil pressure can be the oil pressure after the internal combustion engine 1 is started and at a predetermined engine speed and a predetermined lubricating oil temperature. The actual hydraulic pressure to be compared with the reference hydraulic pressure is a hydraulic pressure detected at a predetermined engine speed and lubricating oil temperature, which are the same conditions as the reference hydraulic pressure. That is, since the actual oil pressure changes according to the engine speed and the lubricating oil temperature, the conditions are matched when comparing the actual oil pressure with the reference oil pressure. The reference oil pressure may be set for each of a plurality of conditions with different engine speeds or different lubricating oil temperatures.

There may be a case where the oil dilution rate is considerably high from the start of the internal combustion engine 1. In such a case, it is conceivable that the oil dilution ratio is still high even when the actual oil pressure increases. Therefore, in the present embodiment, it is assumed that the oil dilution ratio is already high at the time of starting the internal combustion engine 1, and the reference hydraulic pressure is updated with the actual hydraulic pressure thereafter. Here, although the actual oil pressure is higher than the previous reference oil pressure, if the actual oil pressure is decreasing, the oil dilution rate will increase even if the reference oil pressure is not changed. There is a possibility that it is determined that pre-ignition does not occur. On the other hand, by updating the reference oil pressure with a higher actual oil pressure, the oil pressure when the oil dilution rate is lower can be used as a reference, so that an increase in the oil dilution rate can be detected early. Thereby, the determination accuracy of occurrence of pre-ignition can be increased.

  FIG. 3 is a flowchart showing a control flow of the internal combustion engine 1 according to this embodiment. This routine is repeatedly executed by the ECU 10 every predetermined time.

  In step S101, the actual oil pressure at the predetermined engine speed and the predetermined lubricating oil temperature is detected as the reference oil pressure A. In this step, an initial value of the reference oil pressure A is set. It should be noted that a plurality of relationships between the engine speed and the lubricating oil temperature and the actual oil pressure may be obtained and used as the reference oil pressure at each engine speed and the lubricating oil temperature. That is, there may be a plurality of reference oil pressures A. Further, the reference oil pressure A may be an actual oil pressure at the start time of the internal combustion engine 1 (when the internal combustion engine 1 is started and reaches the idling speed), or the warm-up completion time of the internal combustion engine 1 (cooling water temperature or The actual hydraulic pressure at the time when the lubricating oil temperature reaches a predetermined value may be used.

  In step S102, it is determined whether or not an elapsed time after the hydraulic pressure is detected in step S101 is a predetermined value or more. For example, a predetermined value is set as a period during which the oil dilution rate can change. As the predetermined value is decreased, the determination frequency can be increased. However, since the change in the hydraulic pressure due to the change in the oil dilution rate is reduced, the possibility of erroneous determination is increased. Therefore, the predetermined value may be determined in consideration of determination accuracy and determination frequency. Further, the optimum value of the predetermined value may be obtained in advance by experiments or simulations. If an affirmative determination is made in step S102, the process proceeds to step S103. On the other hand, if a negative determination is made, step S102 is executed again. That is, the process proceeds to step S103 after the elapsed time becomes equal to or greater than a predetermined value.

  In step S103, the actual hydraulic pressure B at a predetermined engine speed and a predetermined lubricating oil temperature is detected. In this step, the oil pressure at the same engine speed and lubricating oil temperature as in step S101 is detected. The engine speed and the lubricating oil temperature do not have to be completely the same, and may be different as long as they do not affect the hydraulic pressure. This range can be obtained in advance by experiment or simulation.

  In step S104, it is determined whether the actual oil pressure B is lower than a predetermined range including the reference oil pressure A. In this step, it is determined whether or not pre-ignition occurs due to an increase in the oil dilution rate. That is, if the actual oil pressure B is higher than the predetermined range, it is considered that the actual oil pressure B has increased and the oil dilution rate has decreased. If the actual oil pressure B is lower than the predetermined range, the actual oil pressure B has decreased. It is thought that the oil dilution rate is rising. The predetermined range is a range including the reference oil pressure A, and is determined in consideration of an error, a pressure fluctuation, and the like. Further, the predetermined range may be a range in which the actual oil pressure B can be changed without changing the oil dilution rate. Further, the predetermined range may be a range in which the actual hydraulic pressure B can be considered as not changing from the reference hydraulic pressure A. For the predetermined range, an optimum value may be obtained in advance by experiment or simulation.

  In step S104, it may be determined whether the actual oil pressure B is lower than the reference oil pressure A. Further, the reference oil pressure A may have a certain width. For example, the reference oil pressure A may be a range in which the influence of errors, pressure fluctuations, and the like is considered with respect to the oil pressure detected by the oil pressure sensor 4.

If an affirmative determination is made in step S104, the process proceeds to step S105. In step S105, it is determined that pre-ignition occurs. Furthermore, the internal combustion engine 1
Load is limited. That is, the load is adjusted so that the engine torque is smaller than the pre-ignition region shown in FIG. When limiting the load, the speed of the vehicle on which the internal combustion engine 1 is mounted may not be changed. For example, the transmission may be operated so that the engine speed increases as the engine torque decreases. Further, in a hybrid vehicle including an electric motor, torque may be generated from the electric motor in accordance with a reduction in engine torque. In this embodiment, the ECU 10 that processes step S105 corresponds to the determination means or control means in the present invention.

  On the other hand, if a negative determination is made in step S104, the process proceeds to step S106. In step S106, it is determined whether or not the actual oil pressure B is higher than a predetermined range including the reference oil pressure A. In this step, it is determined whether or not the oil dilution rate has decreased. The predetermined range here is the same as the predetermined range in step S104, but may be different.

  If an affirmative determination is made in step S106, the process proceeds to step S107. In step S107, the value of the reference oil pressure A is replaced with the value of the actual oil pressure B. Here, since the positive determination is made in step S106, the reference oil pressure A is considered to be the oil pressure when oil dilution occurs, so the reference oil pressure A is set to the value when oil dilution does not occur. Change to get closer. By repeating this process, the reference oil pressure A can be brought close to the value when no oil dilution occurs. Thereby, even if it is a case where an oil dilution rate is high from the starting time of the internal combustion engine 1, generation | occurrence | production of pre-ignition can be suppressed.

  If a positive determination is made in step S106 after the load restriction is actually performed in step S105, it is determined that pre-ignition does not occur, assuming that oil dilution has been reduced, and the load restriction is released. In this embodiment, the ECU 10 that processes step S107 corresponds to the reference hydraulic pressure setting means in the present invention.

  On the other hand, if a negative determination is made in step S106, the process returns to step S102. Here, if a negative determination is made in step S106, it can be considered that the oil pressure has not changed, so it is considered that there is no change in the oil dilution rate. Therefore, the process returns to step S102 without doing anything.

  As described above, according to this embodiment, it is possible to determine whether or not pre-ignition occurs based on a change in hydraulic pressure. When pre-ignition can occur, the occurrence of pre-ignition can be suppressed by limiting the load. Thereby, durability of the internal combustion engine 1 can be improved. Further, since it can be determined whether or not pre-ignition occurs based on the reference oil pressure and the actual oil pressure, the oil dilution rate does not need to be actually obtained. Furthermore, when the actual oil pressure is higher than the reference oil pressure, changing the reference oil pressure can accurately determine the occurrence of pre-ignition when the oil dilution ratio is still high, and pre-ignition occurs. Can be suppressed.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Fuel injection valve 3 Spark plug 4 Hydraulic pressure sensor 5 Crank position sensor 6 Accelerator pedal 7 Accelerator opening sensor 10 ECU

Claims (2)

Oil pressure detection means for detecting the pressure of the lubricating oil of the internal combustion engine;
Determining means for determining that abnormal combustion occurs when the pressure of the lubricating oil detected by the oil pressure detecting means is lower than a predetermined range including a reference oil pressure that is a reference value of the lubricating oil pressure of the internal combustion engine;
In an abnormal combustion determination device for an internal combustion engine comprising:
When the pressure of the lubricating oil detected by the hydraulic pressure detection means is higher than the predetermined range, the reference hydraulic pressure that sets the pressure of the lubricating oil detected by the hydraulic pressure detection means at that time as the reference hydraulic pressure thereafter An abnormal combustion determination device for an internal combustion engine comprising setting means. Oil pressure detection means for detecting the pressure of the lubricating oil of the internal combustion engine;
When the pressure of the lubricating oil detected by the hydraulic pressure detecting means is lower than a predetermined range including a reference hydraulic pressure that is a reference value of the pressure of the lubricating oil of the internal combustion engine, control is performed to suppress the occurrence of abnormal combustion. Control means;
An internal combustion engine control apparatus comprising:
When the pressure of the lubricating oil detected by the hydraulic pressure detection means is higher than the predetermined range, the reference hydraulic pressure that sets the pressure of the lubricating oil detected by the hydraulic pressure detection means at that time as the reference hydraulic pressure thereafter An internal combustion engine control device comprising setting means.

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