JP2006194116A - Exhaust emission control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device for an internal combustion engine which gathers and collects exhaust gas fine particulate matters (PM) contained in the exhaust gas of the internal combustion engine by corona discharge, in which it is possible to judge whether a trouble occurs in the exhaust emission control device or not. <P>SOLUTION: The exhaust emission control device includes a judgement means which measures electric current by applying voltage to a discharge electrode so as to judge whether or not a failure occurs in the exhaust emission control device before starting the internal combustion engine based on an insulation resistance value calculated from the measured current value. And especially, the exhaust emission control device includes a judgement means which compares the measured current value with a predetermined current judgement value based on the applied voltage, the exhaust gas temperature and the operating conditions of the internal combustion engine, so as to judge whether or not a failure occurs in the exhaust emission control device before starting the internal combustion engine. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine exhaust gas purification apparatus that collects, collects and collects exhaust particulate (PM) contained in exhaust gas of an internal combustion engine by corona discharge, and can determine whether or not the exhaust gas purification apparatus has failed. The present invention relates to an exhaust emission control device for an engine.

  The treatment of exhaust particulates (PM) contained in the exhaust of an internal combustion engine has become a major issue. As a conventional technique, there is Patent Document 1, which is provided between a pair of electrode portions that are provided with a predetermined interval portion sandwiched in an exhaust path of a diesel engine for a vehicle, and in which a negative electrode electrostatically collects diesel particulates, and between the electrode portions. There has been proposed a technology related to an exhaust gas purifying device for a diesel engine for a vehicle, which has a high voltage power supply unit that supplies a high voltage and generates an electric field for collecting diesel particulates in the gap.

However, the exhaust gas purifying apparatus has a general configuration in which a high voltage is applied between the electrode portions to generate corona discharge to charge negative ions to the diesel particulates. Although there is a statement that a voltage equal to or lower than the discharge generation voltage is applied, in that case, the purpose is to accelerate electrostatically toward the positive electrode. There is no suggestion about the technology to inform.
For this reason, for example, in the above configuration, even when the exhaust purification device is out of order, the driver cannot immediately know it before starting operation or during operation, and leave it without noticing the failure. There is a problem that the exhaust particulate (PM) is not charged efficiently for a long period of time, and as a result, the exhaust particulate (PM) cannot be efficiently aggregated and collected.

JP-A-4-121411

  The present invention seeks to improve the above-mentioned drawbacks of the prior art, and in particular, an internal combustion engine in which exhaust particulates (PM) contained in the exhaust gas of the internal combustion engine are charged by a corona discharge to aggregate and collect. Therefore, an exhaust gas purification apparatus for an internal combustion engine that determines the presence or absence of a failure of the exhaust gas purification apparatus by measuring the current value of the applied voltage is intended to be realized. For this reason, the driver can always check the exhaust purification device for failure at an early stage, and can quickly cope with the failure. As a result, the exhaust particulate matter (PM) is always charged stably and continuously. Further, it is possible to efficiently collect or collect exhaust particulates (PM) using corona discharge, and to realize a practical and high performance exhaust purification device for an internal combustion engine.

  In the exhaust gas purification apparatus for an internal combustion engine according to claim 1, a high voltage is applied between the electrodes in the exhaust part of the internal combustion engine to generate corona discharge to charge the exhaust particulates and to aggregate the charged exhaust particulates. The exhaust gas purification apparatus for an internal combustion engine to be collected is characterized by comprising a judging means for judging whether or not there is a failure of the exhaust gas purification apparatus based on the measured current value.

  Since the internal combustion engine exhaust gas purification device has such a configuration, since it is a very simple device that can determine whether or not the exhaust gas purification device has failed only from the measured current value, it is compact. Yes, it is very suitable for mounting on a car. For this reason, as a result, the driver can always easily check whether or not the exhaust purification device is out of order before starting operation or during operation, and in the event of a failure, it has the effect of being able to quickly cope with it. Is.

  According to a second aspect of the present invention, preferably, the determination means determines whether or not the exhaust purification device has failed before starting the internal combustion engine based on an insulation resistance value calculated from the measured current value. It is.

  Experience shows that if the inside of the exhaust gas purification device, especially the insulator part, is contaminated with exhaust particulates (PM), the insulation resistance value is significantly lower than a certain normal value. As a result, the voltage does not increase even when a high voltage is applied. It becomes an abnormal state where it descends. Therefore, the exhaust gas purification device before starting the internal combustion engine is calculated by calculating the insulation resistance value based on the measured current value (resistance value R = applied voltage V / current I) and checking the difference between the insulation resistance value and the normal value. There is an effect that it is possible to easily check whether or not there is a failure.

  As in the invention of claim 3, the measured current value is a current value corresponding to application of a low voltage equal to or lower than the corona discharge generation voltage.

  Since it is such a structure, there exists an effect that power consumption can be suppressed as much as possible and the presence or absence of a failure of an exhaust gas purification apparatus can be checked.

  In the exhaust emission control device for an internal combustion engine according to claim 4, the determination means compares and determines a preset current judgment value based on the applied voltage, the exhaust gas temperature, and the internal combustion engine operating condition, and the measured current value. Thus, it is a determination means for determining whether or not the exhaust gas purification device has failed after the internal combustion engine is started.

  In general, an applied voltage value is set based on the exhaust gas temperature and the amount of exhaust particulates (PM) contained in the exhaust gas, and a corona discharge is generated in the exhaust purification device by applying the set voltage. Has been done. The amount of exhaust particulate (PM) is calculated according to the internal combustion engine operating conditions. Therefore, when the applied voltage, exhaust gas temperature, and internal combustion engine operating conditions are set, the current value must be within a certain normal value range unless there is a malfunction of the apparatus. According to the present invention configured as described above, in the electronic control unit (ECU), the current judgment value set in advance according to the applied voltage, the exhaust gas temperature and the operating condition of the internal combustion engine is compared with the measured current value. Thus, after starting the internal combustion engine, that is, during driving of the vehicle, it is possible to always determine whether or not the exhaust purification device has failed, and the driver can deal with the failure of the exhaust purification device at an early stage. It plays.

  According to a fifth aspect of the invention, the internal combustion engine operating conditions are an internal combustion engine speed and a fuel injection amount.

  By configuring in this way, it is possible to reliably predict the change in the amount of exhaust particulate (PM) generation, and as a result, it is possible to accurately determine whether or not the exhaust purification device has failed.

  Due to such a configuration, the exhaust gas purification apparatus for an internal combustion engine according to the present invention is a very simple and compact apparatus that determines whether or not there is a failure of the exhaust gas purification apparatus based only on the measured current value, and is mounted on a vehicle. Very suitable for doing. For this reason, the driver can always easily check whether or not the exhaust gas purification device is out of order before or during operation, and can quickly cope with the failure. As a result, the exhaust particulates (PM) are constantly and stably charged to enable efficient aggregation or collection of the exhaust particulates (PM) using corona discharge, which is a practical and high-performance internal combustion engine. An exhaust purification device for an engine can be realized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the overall configuration of an exhaust gas purification apparatus for an internal combustion engine according to the present invention. Reference numeral 1 denotes a housing of the exhaust gas purification apparatus, which is made of stainless steel (SUS) and is electrically installed. Although not shown, the left end portion of the housing 1 is connected to an internal combustion engine (engine) via an exhaust pipe, and exhaust gas flows in from the left side of the drawing. Similarly, a stainless steel (SUS) conductive mesh 2 is disposed along the transverse direction on the downstream side (right side) of the central cylindrical portion of the housing 1, and the housing 1 is tapered to the left and right of the central cylindrical portion. Is forming. Further, the discharge electrode 3 is fixed to the wall portion at the upper center of the central cylindrical portion of the housing 1 by existing appropriate fixing means. The discharge electrode 3 hangs an L-shaped discharge part 3b from the insulator 3a inside the housing 1.

  The discharge electrode 3 is connected to a high-voltage power supply 4 (preferably a variable voltage type), and a voltmeter 6 and an ammeter 7 are connected between the discharge electrode 3 and the high-voltage power supply 4. A temperature sensor 5 for detecting the exhaust gas temperature is provided near the upstream side entrance of the housing 1 so as to constantly detect the temperature of the exhaust gas flowing in the exhaust purification device. The exhaust gas purification apparatus of the present invention is provided with an electronic control unit (ECU) 8 serving as a control means at an appropriate location. As will be described in detail later, data from the temperature sensor 5 and ammeter 7, and further, an internal combustion engine. The internal combustion engine speed and fuel injection amount data are always transferred from the engine system, and the current judgment value set in advance by setting and controlling the applied voltage value, as well as the applied voltage, exhaust gas temperature, internal combustion engine speed and fuel injection amount. And the current value sent from the ammeter 7 at all times. In the present invention, the discharge electrode 3 is a negative electrode, and a negative DC high voltage is applied to generate a corona discharge. Reference numeral 9 denotes exhaust particulates (PM).

FIG. 2 is a flowchart of the failure determination of the exhaust gas purification apparatus by the ECU 8, and will be described along the respective stage numbers S1 to S13.
First, before starting the engine, the start key of the exhaust emission control device is turned on (S1). At the same time, in order to measure the insulation resistance value, a low voltage that does not generate corona discharge is applied to the discharge electrode 3 (S2), and the current value is measured by the ammeter 7 (S3). The insulation resistance value Ra is calculated from the measured current value Ia and the applied voltage Va by the equation Ra = Va / Ia (S4), and it is determined whether or not the insulation is normal (S5).

The determination will be described with reference to the failure determination standard (before starting) in FIG. In general, the insulation resistance value is unique to each exhaust purification device, and the resistance value gradually decreases as exhaust particulates accumulate on the inner surface of the housing 1 or the insulator portion due to the period of use or the like and contamination progresses.
Therefore, a normal value range or a limit value that becomes an abnormal value is grasped in advance and input to the ECU 8, and compared with the insulation resistance value calculated from the current value measured when the failure inspection is performed. The In FIG. 3, for example, the normal value before use of the device is 1000 MΩ, the limit value due to contamination is 100 MΩ, and the device is clearly abnormal at a level of 10 MΩ that is significantly lower than that. In this way, when the numerical value is abnormal, the failure lamp is lit to notify the driver (S12), and the use of the exhaust purification device is stopped (S13). On the other hand, if the numerical value is within a normal range, the switch of the internal combustion engine is turned on to start driving the vehicle (S6).

  Next, when the internal combustion engine (engine) is started, the exhaust gas temperature is measured by the temperature sensor 5 and the exhaust gas temperature data is transferred to the ECU 8 (S7), and is equal to or higher than a preset condensation temperature (for example, 70 ° C.). Then, the switch of the high-voltage power supply 4 is turned on, and the preparation for starting the corona discharge is completed in the housing 1.

  When the internal combustion engine is started, data regarding the rotational speed and fuel injection amount of the internal combustion engine is separately measured by the internal combustion engine system and is always transferred to the ECU 8. The ECU 8 predicts the amount of exhaust particulate (PM) contained in the exhaust gas based on the internal combustion engine speed and the fuel injection amount (S7). In this way, the ECU 8 always holds data regarding the exhaust gas temperature and the amount of exhaust particulates (PM) contained in the exhaust gas.

Next, the ECU 8 enters an applied voltage value setting operation (S8).
Separately, a map I indicating the correlation between the exhaust gas temperature and the amount of exhaust particulates (PM) contained in the exhaust gas and the set voltage value is created and input in advance through experiments. . According to experiments, arc discharge occurs at a lower voltage as the exhaust gas temperature is higher, and further, arc discharge occurs at a lower voltage when the amount of exhaust particulates (PM) in the exhaust gas is larger than when it is small. It has been made clear. In the ECU 8, the applied voltage value is always generated by analyzing the data regarding the exhaust gas temperature and the amount of exhaust particulates (PM) contained in the exhaust gas and the data on the map I. It is set to be lower than the expected voltage value (S8).

  Next, corona discharge is generated in the exhaust purification device by applying a set voltage (S9). Thereafter, the current is measured by an ammeter (S10), and a current judgment value set in advance based on the applied voltage, the exhaust gas temperature and the operating condition of the internal combustion engine is compared with the measured current value. The preset current judgment value actually consists of a certain range between the upper limit current judgment value and the lower limit current judgment value, and whether or not the measured current value is included in the current judgment value within the certain range. It is determined whether or not a failure has occurred in the exhaust emission control device (S11).

In detail, it demonstrates, referring the example of failure criteria (after starting) of FIG. In FIG. 4, the horizontal axis represents the changing exhaust gas temperature (° C.), and the vertical axis represents the current value (mA). The range in which the exhaust emission control device is operating normally is indicated by two thick dotted lines, and the current value corresponding to each dotted line for each temperature is the upper limit current judgment value or the lower limit current judgment value for normal operation. . The upper limit current judgment value or the lower limit current judgment value is determined or fluctuates depending on changes in the applied voltage value, the internal combustion engine speed, the fuel injection amount, and the exhaust gas temperature. However, as described above, the applied voltage value is calculated and set based on the internal combustion engine speed, the fuel injection amount, and the exhaust gas temperature. Therefore, in practice, the upper limit current judgment value data and the lower limit current judgment value data are obtained for each point by conducting an experiment in advance using three kinds of factors, that is, the internal combustion engine speed, the fuel injection amount, and the exhaust gas temperature. Is input to the ECU 8 as Map II. The data acquired by the ECU 8 every moment, that is, the current value acquired during operation under a certain applied voltage, internal combustion engine speed, fuel injection amount and exhaust gas temperature is above the dotted line of the upper limit current judgment value. In such a case, dirt such as exhaust particulate (PM) is accumulated inside the housing 1 or the conductive mesh 2 to cause poor insulation, or the conductive mesh 2 (shown as mesh in FIG. 4) is in a long period. It is determined that it has moved to a position close to the discharge electrode.
On the other hand, when the current value acquired during the above operation is below the dotted line of the lower limit current judgment value, the discharge is insufficient, the cable is disconnected halfway, or the conductive net 2 (in FIG. 4). In this case, it is determined that the mesh has been moved away from the discharge electrode due to a long-term vibration or the like.

  Therefore, when the current value acquired during operation exceeds the upper limit current judgment value of the normal range, or when it is below the lower limit current judgment value of the normal value, the failure lamp is turned on (S12). The driver is notified of the failure, and the driver receives this and stops the exhaust purification device. In this case, there are two types of fault lamps (not shown) so that it is possible to determine whether the current value exceeds the upper limit current judgment value of the normal value and is faulty or is lower than the lower limit current judgment value so that the fault occurs. It is also possible to provide a lighting lamp.

  Further, when the current value is between the two dotted lines, that is, within the range of normal operation, the driver continues to operate while the switch of the exhaust purification device remains on. The ECU 8 calculates the amount of exhaust particulates (PM) based on the internal combustion engine speed and fuel injection amount that are continuously transferred, and always falls below the expected arc discharge occurrence voltage value in association with the map I together with the temperature data. The applied voltage value is set by and voltage application is performed (S7 to S9 are repeated). In addition, the exhaust gas purification device is within the normal operation range by continuously matching the current value obtained by the ammeter with the above map II together with the applied voltage value, the internal combustion engine speed, the fuel injection amount, and the exhaust gas temperature. The determination of whether or not is continued (S11).

  Thus, since it is the above configuration, the exhaust gas purification device for an internal combustion engine according to the present invention is a very simple and compact device that determines the presence or absence of a failure of the exhaust gas purification device based on the measured current value. Very suitable for mounting on a car. For this reason, the driver can always easily check whether or not the exhaust emission control device is out of order before starting operation or during operation, and has the effect of being able to quickly cope with a failure. . As a result, the exhaust particulates (PM) are constantly and stably charged to enable efficient aggregation or collection of the exhaust particulates (PM) using corona discharge, which is a practical and high-performance internal combustion engine. An exhaust purification device for an engine can be realized.

1 is an overall configuration diagram of an exhaust gas purification apparatus for an internal combustion engine in an embodiment of the present invention. 3 is a flowchart for failure determination by an ECU in the exhaust gas purification apparatus for an internal combustion engine in the embodiment of the present invention. It is an image figure which showed the idea of the failure judgment standard (before internal combustion engine starting) in the exhaust gas purification apparatus for internal combustion engines in embodiment of this invention. It is an image figure showing a way of thinking of a failure judgment standard (after an internal combustion engine start) in an exhaust gas purification device for an internal combustion engine in an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 2 Conductive net | network 3 Discharge electrode 3a insulator 3b Discharge part 4 High voltage power supply 5 Temperature sensor 6 Voltmeter 7 Ammeter 8 ECU
9 Exhaust particulate (PM)

Claims (5)

  Measurement in an exhaust purification system for an internal combustion engine that collects corona discharge by charging corona discharge by applying a high voltage between the electrodes at the exhaust part of the internal combustion engine and aggregating and collecting the charged exhaust particulates An exhaust emission control device for an internal combustion engine, comprising: determination means for determining whether or not there is a failure of the exhaust emission control device based on the current value.   2. The determination means according to claim 1, wherein the determination means is a determination means for determining whether or not the exhaust purification device has failed before starting the internal combustion engine based on an insulation resistance value calculated from the measured current value. Exhaust gas purification device for internal combustion engine.   3. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the measured current value is a current value corresponding to application of a low voltage equal to or lower than a corona discharge generation voltage.   The determination means compares the current determination value set in advance with the measured current value based on the applied voltage, the exhaust gas temperature, and the internal combustion engine operating condition, thereby determining the exhaust purification device after the start of the internal combustion engine. 2. The exhaust gas purification apparatus for an internal combustion engine according to claim 1, wherein the exhaust gas purification apparatus is a determination unit that determines whether or not there is a failure.   The internal combustion engine exhaust gas purification apparatus according to claim 4, wherein the internal combustion engine operating conditions are an internal combustion engine speed and a fuel injection amount.

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