JP2010024848A - Automatic stopping and restarting device of internal combustion engine - Google Patents

Abstract

An automatic stop / restart apparatus for an internal combustion engine provides a technique for accurately estimating a catalyst bed temperature even during an automatic stop of the internal combustion engine.
An automatic control means for automatically stopping an internal combustion engine when an automatic stop condition is satisfied and automatically restarting the internal combustion engine when an automatic restart condition is satisfied, and an exhaust control passage disposed in the internal combustion engine And an exhaust temperature sensor disposed in an exhaust passage upstream of the DPNR and detecting an exhaust temperature upstream of the DPNR, and the automatic control means automatically stops the internal combustion engine during the automatic stop. The DPNR floor temperature is estimated based on the DPNR upstream exhaust temperature detected by, and the automatic stop map representing the temperature difference between the DPNR upstream exhaust temperature and the DPNR temperature.
[Selection] Figure 5

Description

  The present invention relates to an automatic stop / restart device for an internal combustion engine.

  2. Description of the Related Art In recent years, vehicles that perform control to automatically stop an internal combustion engine when a preset automatic stop condition is satisfied and to automatically restart the internal combustion engine when an automatic restart condition is satisfied during the automatic stop have become widespread. ing. Such vehicles include eco-run (economy running) vehicles and hybrid vehicles.

  In these vehicles, it is possible to perform so-called idling stop control in which the internal combustion engine is automatically stopped at a temporary stop such as waiting for a signal and the internal combustion engine is restarted when the vehicle restarts. In addition, since the hybrid vehicle includes a driving source (for example, an electric motor) in addition to the internal combustion engine, the internal combustion engine is controlled to be automatically stopped or automatically restarted according to the operating conditions or the like even while the vehicle is running. be able to. As a result, it is possible to improve fuel consumption and reduce emissions.

  Even in such a vehicle, in order to achieve both protection of the catalyst disposed in the exhaust passage of the internal combustion engine and improvement in fuel consumption, estimation of the catalyst bed temperature is performed. However, during the automatic stop of the internal combustion engine, if the catalyst bed temperature is estimated in the same manner as during the operation of the internal combustion engine, there may be a difference between the estimated catalyst bed temperature and the actual catalyst bed temperature.

For this reason, a technique is disclosed in which the catalyst bed temperature is estimated based on a predetermined value for stopping the internal combustion engine during the automatic stop of the internal combustion engine (see, for example, Patent Document 1).
JP 2001-173504 A JP 2007-113467 A JP 2007-239472 A JP 2006-291837 A

  However, as described in Patent Document 1, when estimating the catalyst bed temperature during the automatic stop of the internal combustion engine, it is based on a predetermined value regardless of the stop time during the automatic stop of the internal combustion engine. In some cases, such as when the operation is stopped for some time, there may be a difference between the estimated catalyst bed temperature and the actual catalyst bed temperature.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technology for accurately estimating the catalyst bed temperature even during the automatic stop of the internal combustion engine in the automatic stop and restart device of the internal combustion engine. There is to do.

In the first aspect of the present invention, the following configuration is adopted. That is, the first aspect of the present invention is
Automatic control means for automatically stopping the internal combustion engine when the automatic stop condition is satisfied and automatically restarting the internal combustion engine when the automatic restart condition is satisfied;
A catalyst disposed in an exhaust passage of the internal combustion engine for purifying exhaust;
A near-catalyst exhaust temperature detecting means that is disposed in an exhaust passage near the catalyst and detects a near-catalyst exhaust temperature;
While the automatic control means automatically stops the internal combustion engine, the automatic stop that represents the exhaust temperature near the catalyst detected by the exhaust gas temperature detecting means near the catalyst and the temperature difference between the exhaust gas temperature near the catalyst and the catalyst temperature A first automatic stop catalyst bed temperature estimating means for estimating the catalyst bed temperature based on
An automatic stop / restart device for an internal combustion engine.

  In order to achieve both protection of the catalyst disposed in the exhaust passage of the internal combustion engine and improvement of fuel consumption, estimation of the catalyst bed temperature is performed. However, during the automatic stop of the internal combustion engine, if the catalyst bed temperature is estimated in the same manner as during the operation of the internal combustion engine, there may be a difference between the estimated catalyst bed temperature and the actual catalyst bed temperature.

  Therefore, in the present invention, during the automatic stop of the internal combustion engine, the near-catalyst exhaust temperature detected by the near-catalyst exhaust temperature detection means and the automatic stop map that represents the temperature difference between the near-catalyst exhaust temperature and the catalyst temperature. Based on this, the catalyst bed temperature was estimated.

  During the automatic stop of the internal combustion engine, there is a strong correlation between the near-catalyst exhaust temperature detected by the near-catalyst exhaust temperature detecting means and the catalyst temperature. For this reason, if the correlation between the exhaust temperature near the catalyst and the catalyst temperature is previously stored as an automatic stop map, the exhaust gas temperature detection means near the catalyst detects the exhaust temperature near the catalyst, thereby The catalyst bed temperature during stoppage can be estimated. Therefore, the catalyst bed temperature during the automatic stop of the internal combustion engine can be accurately estimated.

In the second present invention, the following configuration is adopted. That is, the second aspect of the present invention
Automatic control means for automatically stopping the internal combustion engine when the automatic stop condition is satisfied and automatically restarting the internal combustion engine when the automatic restart condition is satisfied;
A catalyst disposed in an exhaust passage of the internal combustion engine for purifying exhaust;
A catalyst inflow exhaust gas temperature detection means for detecting a catalyst inflow exhaust gas temperature disposed in an exhaust passage immediately upstream of the catalyst;
A catalyst outflow exhaust temperature detecting means disposed in an exhaust passage immediately downstream of the catalyst and detecting a catalyst outflow exhaust temperature;
An inflow side representing a catalyst inflow / exhaust temperature detected by the catalyst inflow / exhaust temperature detection means and a temperature difference between the catalyst inflow / exhaust temperature and the catalyst temperature during the automatic stop when the internal combustion engine is automatically stopped by the automatic control means An automatic stop map; and an inflow-side automatic stop catalyst bed temperature estimating means for estimating the catalyst bed temperature based on the map;
An outflow side representing a catalyst outflow exhaust temperature detected by the catalyst outflow exhaust temperature detection means and a temperature difference between the catalyst outflow exhaust temperature and the catalyst temperature during the automatic stop in which the automatic control unit automatically stops the internal combustion engine. An automatic stop map, and an outflow side automatic stop catalyst bed temperature estimating means for estimating the catalyst bed temperature based on the map,
The automatic control means sets the reflection ratio between the catalyst bed temperature estimated by the inflow-side automatic stop catalyst bed temperature estimation means and the catalyst bed temperature estimated by the outflow-side automatic stop catalyst bed temperature estimation means. Change is made according to the difference between the catalyst upstream bed temperature and the catalyst downstream bed temperature immediately before the engine is automatically stopped, and the automatic control means estimates the catalyst bed temperature during the automatic stop when the internal combustion engine is automatically stopped. A second catalyst bed temperature estimating means during automatic stop;
An automatic stop / restart device for an internal combustion engine.

  There may be a difference between the bed temperature on the upstream side of the catalyst and the bed temperature on the downstream side of the catalyst. At this time, if the catalyst bed exhaust temperature is detected from the catalyst inflow exhaust temperature detection means disposed in the exhaust passage immediately upstream of the catalyst and the catalyst bed temperature is estimated, the estimated catalyst bed temperature becomes a temperature close to the catalyst upstream bed temperature. In some cases, the bed temperature on the downstream side of the catalyst may deviate. Here, on the downstream side of the catalyst, there is a high possibility that the catalyst bed temperature is raised to a temperature higher than the allowable temperature. For this reason, it is desirable that the estimated catalyst bed temperature is calculated at a temperature closer to the catalyst downstream bed temperature than the catalyst upstream bed temperature.

  Therefore, in the present invention, when there is a difference between the catalyst upstream bed temperature immediately before the automatic stop and the catalyst downstream bed temperature, the catalyst bed temperature estimated by the catalyst bed temperature estimating means during the inflow side automatic stop, and the outflow side The reflection ratio of the catalyst bed temperature estimated by the catalyst bed temperature estimating means during automatic stop is changed according to the difference, and the automatic control means estimates the catalyst bed temperature during automatic stop when the internal combustion engine is automatically stopped. I made it.

  According to the present invention, the larger the difference between the catalyst upstream bed temperature immediately before the automatic stop and the catalyst downstream bed temperature, the larger the reflection ratio of the catalyst bed temperature estimated by the catalyst bed temperature estimating means during the outflow side automatic stop can be increased. . For this reason, the estimated catalyst bed temperature can be calculated at a temperature closer to the catalyst downstream bed temperature than the catalyst upstream bed temperature. Therefore, the catalyst bed temperature during the automatic stop of the internal combustion engine can be accurately estimated.

In the third aspect of the present invention, the following configuration is adopted. That is, the third aspect of the present invention
Automatic control means for automatically stopping the internal combustion engine when the automatic stop condition is satisfied and automatically restarting the internal combustion engine when the automatic restart condition is satisfied;
A catalyst disposed in an exhaust passage of the internal combustion engine for purifying exhaust;
A heat release amount calculation means during automatic stop for calculating a heat release amount of each part of the catalyst divided into a plurality of parts in the exhaust flow direction during the automatic stop when the automatic control means automatically stops the internal combustion engine;
An automatic stop heat transfer amount calculating means for calculating the heat transfer amount between the adjacent parts of the catalyst that are automatically stopped by the automatic control means automatically stopping the internal combustion engine;
The automatic control means automatically calculates the heat release amount calculated by the heat release amount calculation means during automatic stop and the heat transfer amount calculated by the heat transfer amount calculation means during automatic stop to the bed temperature of each part of the catalyst immediately before the internal combustion engine is automatically stopped. A catalyst bed temperature estimating means during automatic stop for estimating the bed temperature of each part of the catalyst during automatic stop in which the automatic control means automatically stops the internal combustion engine;
An automatic stop / restart device for an internal combustion engine.

  According to the present invention, the catalyst bed temperature can be estimated in consideration of the heat release amount and heat transfer amount of the catalyst during the automatic stop of the internal combustion engine. Therefore, the catalyst bed temperature during the automatic stop of the internal combustion engine can be accurately estimated.

  According to the present invention, in the automatic stop / restart device for an internal combustion engine, the catalyst bed temperature can be accurately estimated even during the automatic stop of the internal combustion engine.

  Specific examples of the present invention will be described below.

<Example 1>
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which an automatic stop / restart device for an internal combustion engine according to the present embodiment is applied and an intake system / exhaust system thereof. An internal combustion engine 1 shown in FIG. 1 is a water-cooled four-stroke cycle diesel engine having four cylinders. The vehicle on which the internal combustion engine 1 is mounted is an eco-run (economy running) vehicle. The internal combustion engine 1 is automatically stopped when the vehicle is temporarily stopped, and the internal combustion engine 1 is automatically restarted when the vehicle restarts. Stop control is performed. An intake passage 2 and an exhaust passage 3 are connected to the internal combustion engine 1.

  An air flow meter 4 that outputs a signal corresponding to the flow rate of fresh intake air (hereinafter referred to as fresh air) flowing through the intake passage 2 is disposed in the middle of the intake passage 2 connected to the internal combustion engine 1. Yes. The air flow meter 4 measures the fresh air amount (intake air amount) Ga of the internal combustion engine 1. The intake passage 2 and the devices disposed in the intake passage 2 constitute an intake system of the internal combustion engine 1.

  On the other hand, in the middle of the exhaust passage 3 connected to the internal combustion engine 1, a particulate filter (hereinafter referred to as NOx catalyst) that carries a storage reduction type NOx catalyst (hereinafter referred to as NOx catalyst) and collects particulate matter (PM) in the exhaust gas. 5) (referred to as DPNR). The NOx catalyst supported on the DPNR 5 stores NOx in the exhaust when the internal combustion engine 1 is in a normal operation state where the oxygen concentration of the exhaust flows is high, the oxygen concentration of the exhaust flowing in decreases, and the reducing agent When NO exists, it has the characteristic of releasing and reducing the stored NOx. DPNR5 in this example corresponds to the catalyst of the present invention.

  In the exhaust passage 3 upstream of the DPNR 5, a fuel addition valve 6 that adds fuel (light oil) as a reducing agent to the exhaust gas flowing through the exhaust passage 3 is disposed. The fuel addition valve 6 is opened by a signal from the ECU 20 described later to add fuel. The fuel added to the exhaust gas in the exhaust passage 3 from the fuel addition valve 6 makes the exhaust air-fuel ratio flowing into the DPNR 5 rich to release and reduce NOx occluded in the DPNR 5, or flows into the DPNR 5. The temperature of DPNR5 can be raised to oxidize and remove PM.

  An exhaust temperature sensor 7 for detecting the temperature of the exhaust gas flowing into the DPNR 5 is disposed in the exhaust passage 3 immediately upstream of the DPNR 5. The exhaust temperature sensor 7 in this embodiment corresponds to the catalyst vicinity exhaust temperature detection means of the present invention. The temperature of the exhaust gas flowing into the DPNR 5 in this embodiment corresponds to the exhaust temperature near the catalyst of the present invention. Note that the exhaust temperature sensor near the catalyst may be an exhaust temperature sensor disposed in the exhaust passage 3 immediately downstream of the DPNR 5. The exhaust passage 3 and the devices arranged in the exhaust passage 3 constitute an exhaust system of the internal combustion engine 1.

  The internal combustion engine 1 is provided with a fuel injection valve 8 that supplies fuel into the cylinder of the internal combustion engine 1. A starter motor 9 for starting the internal combustion engine 1 is attached to the internal combustion engine 1. The starter motor 9 is driven by electric power supplied from a battery (not shown). A pinion gear (not shown) is attached to the drive shaft of the starter motor 9, and a link gear (not shown) attached to one end of the crankshaft of the internal combustion engine 1 is driven by the pinion gear. By driving such a starter motor 9, the internal combustion engine 1 can be cranked and started.

  The internal combustion engine 1 configured as described above is provided with an ECU 20 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 20 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver.

  In addition to the air flow meter 4 and the exhaust gas temperature sensor 7, the ECU 20 includes an accelerator opening sensor 10 that outputs an electric signal corresponding to the amount of depression of the accelerator pedal, and a brake opening that outputs an electric signal corresponding to the amount of depression of the brake pedal. Various sensors such as a sensor 11, a crank position sensor 12 that detects the engine speed of the internal combustion engine 1, and a vehicle speed sensor 13 that outputs an electric signal corresponding to the speed (vehicle speed) of the vehicle are connected via an electrical wiring. Output signals from various sensors are input to the ECU 20.

  On the other hand, a fuel addition valve 6, a fuel injection valve 8, and a starter motor 9 are connected to the ECU 20 via electric wiring, and these devices are controlled by the ECU 20.

  Then, the ECU 20 automatically stops the internal combustion engine 1 when the eco-run vehicle of this embodiment is temporarily stopped due to a signal waiting at an intersection or the like, and automatically restarts the internal combustion engine 1 when the vehicle restarts. A so-called idling stop control is performed.

The idling stop condition (automatic stop condition), which is an execution condition of the idling stop control, is that when the ignition is on, for example, a vehicle speed detection signal from the vehicle speed sensor 13 detects that the vehicle speed is 0, and a brake opening sensor This is established when it is detected that a brake pedal depression operation is being performed by a brake pedal depression signal (brake opening degree) 11. When the idling stop condition is satisfied, the ECU 20 issues a command to the fuel injection valve 8 to automatically stop the internal combustion engine 1 by stopping the fuel injection (fuel cut).

  On the other hand, the idling stop cancellation condition (automatic restart condition), which is the cancellation condition of the idling stop control, is that the brake pedal depressing release operation is performed by the brake pedal depressing cancellation signal from the brake opening sensor 11 after the idling stop condition is satisfied. It is established when it is detected that this has been done. When the idling stop cancellation condition (automatic restart condition) is satisfied while the internal combustion engine 1 is automatically stopped, the ECU 20 issues a command to the fuel injection valve 8 and the starter motor 9 to start fuel injection and to start the starter motor 9. The engine is operated to perform cranking, and the internal combustion engine 1 is automatically restarted.

  The conditions for satisfying such an idling stop condition and an idling stop cancellation condition are examples, and may be based on other conditions. Here, the ECU that executes the idling stop control in this embodiment corresponds to the automatic control means of the present invention.

  By the way, in the DPNR 5 arranged in the exhaust passage 3, the collected PM increases with the operation time of the internal combustion engine 1. When the collected PM in DPNR5 increases, the back pressure of internal combustion engine 1 increases due to an increase in the flow resistance in DPNR5, resulting in a decrease in engine output. Therefore, in order to recover the PM trapping ability of DPNR5, when the amount of PM deposited on DPNR5 exceeds a predetermined amount, fuel is added from fuel addition valve 6, and the fuel is reacted using the NOx catalyst of DPNR5. PM forced oxidation removal control for forcibly oxidizing and removing PM from DPNR5 by raising the temperature to a high temperature may be performed.

  The bed temperature of the DPNR 5 is estimated in order to optimize the execution time of such PM forced oxidation removal control and to prevent the bed temperature of the DPNR 5 from being raised to a temperature higher than the allowable temperature. The estimated DPNR bed temperature (also referred to as estimated DPNR bed temperature) in the present embodiment corresponds to the estimated catalyst bed temperature of the present invention.

Next, the DPNR bed temperature estimation method will be described. Estimated DPNR bed temperature is
Estimated DPNR floor temperature = detected temperature of exhaust temperature sensor 7 + temperature difference between detected temperature of exhaust temperature sensor 7 and DPNR temperature + PM calorific value (Expression 1)
Is calculated from

  Here, the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature has a strong correlation between the detected temperature detected by the exhaust temperature sensor 7 and the amount of fresh air detected by the air flow meter 4. Therefore, the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature is shown in FIG. 2 according to the detected temperature detected by the exhaust temperature sensor 7 and the fresh air amount detected by the air flow meter 4 in advance. It can be set as a map. Therefore, the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature is calculated from the detected temperature detected by the exhaust temperature sensor 7 and the fresh air amount detected by the air flow meter 4 using the map of FIG. Is done.

  Further, the PM heat generation amount is calculated from detection values of various sensors that detect the operation state of the internal combustion engine 1 using a map corresponding to the operation state of the internal combustion engine 1.

Thus, the estimated DPNR bed temperature calculated from Equation 1 is approximately equal to the actual DPNR bed temperature during operation of the internal combustion engine 1. However, during the automatic stop in which the internal combustion engine 1 is automatically stopped by the idling stop control, the estimation method uses the estimation D
The PNR bed temperature has deviated from the actual DPNR bed temperature.

  This is because when the internal combustion engine 1 is automatically stopped, the detected temperature detected by the exhaust temperature sensor 7 is, for example, 450 ° C. or less, which is excessively low compared to when the internal combustion engine 1 is operating, The amount of fresh air detected by the engine 4 may be excessively small as compared with the operation of the internal combustion engine 1, for example, 15 g / s or less. In this case, the amount of fresh air is outside the range of the map shown in FIG. Therefore, the temperature difference between the temperature detected by the exhaust temperature sensor 7 and the DPNR temperature cannot be calculated correctly.

  Therefore, in the present embodiment, during the automatic stop of the internal combustion engine 1, the map is different from that during the operation of the internal combustion engine 1, and the automatic stop is used to calculate the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature. Added a map.

  Here, as shown in FIG. 3, the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature during the automatic stop of the internal combustion engine 1 has a strong correlation only with the detected temperature detected by the exhaust temperature sensor 7. is there. Therefore, as shown in FIG. 4, the automatic stop map can be provided as a map corresponding to only the detected temperature detected by the exhaust temperature sensor 7.

  Therefore, even when the internal combustion engine 1 is automatically stopped, the estimated DPNR floor temperature is estimated using Equation 1, but the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature in Equation 1 is the automatic stop of FIG. It is calculated from the detected temperature detected by the exhaust temperature sensor 7 using the map for operation.

  Therefore, according to the present embodiment, even during the automatic stop of the internal combustion engine 1, the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature can be accurately calculated, and the estimation during the automatic stop of the internal combustion engine 1 is possible. DPNR bed temperature can be calculated accurately. Thereby, the learning of the fuel addition valve 6 at the time of restart of the internal combustion engine 1 and the calculation of the oxidation rate of the collected PM in the DPNR 5 are correctly performed, and the fuel efficiency is deteriorated by optimizing the execution time of the PM forced oxidation removal control. It is possible to prevent the DPNR 5 from being heated to a temperature higher than the allowable temperature.

  Next, an estimated DPNR bed temperature calculation control routine according to this embodiment will be described. FIG. 5 is a flowchart showing an estimated DPNR bed temperature calculation control routine according to this embodiment. This routine is repeatedly executed every predetermined time. The ECU 20 that executes this routine corresponds to the first catalyst bed temperature estimating means during automatic stop according to the present invention.

  In step S101, the ECU 20 detects the operating state of the internal combustion engine 1. The operating state of the internal combustion engine 1 is obtained from detection values of various sensors such as an air flow meter 4, an exhaust temperature sensor 7, an accelerator opening sensor 10, a brake opening sensor 11, a crank position sensor 12, and a vehicle speed sensor 13.

  In step S102, the ECU 20 determines whether or not the internal combustion engine 1 is being automatically stopped. When the idling stop condition is satisfied from the operating state of the internal combustion engine 1 detected in step S101, it can be determined that the internal combustion engine 1 is automatically stopped.

  If it is determined in step S102 that the internal combustion engine 1 is automatically stopped, the process proceeds to step S103. If it is determined in step S102 that the internal combustion engine 1 is operating rather than being automatically stopped, the process proceeds to step S104.

  In step S103, the ECU 20 sets a map for calculating a temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature in Expression 1 to the automatic stop map shown in FIG.

  On the other hand, in step S104, the ECU 20 sets a map for calculating the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature in Equation 1 to a map used during operation of the internal combustion engine 1 shown in FIG. .

  In step S105, the ECU 20 calculates the estimated DPNR bed temperature based on Equation 1. Here, when passing through step S103, the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature is calculated using the automatic stop map shown in FIG. On the other hand, when passing through step S104, the temperature difference between the detected temperature of the exhaust temperature sensor 7 and the DPNR temperature is calculated using a map used during operation of the internal combustion engine 1 shown in FIG.

  According to the routine described above, the internal combustion engine 1 is automatically stopped by switching between the automatic stop map and the map used while the internal combustion engine 1 is operating depending on whether the internal combustion engine 1 is automatically stopped or operating. The estimated DPNR bed temperature can be accurately calculated both during operation and during operation.

  In the above embodiment, since DPNR was adopted as the catalyst of the present invention, the calorific value of PM collected in DPNR was incorporated in Equation 1, but PM was not collected as the catalyst of the present invention. If it is a catalyst, the calorific value of PM is not taken into consideration, and Equation 1 can be calculated as “estimated catalyst bed temperature = detected temperature of exhaust temperature sensor + temperature difference between detected temperature of exhaust temperature sensor and catalyst temperature”. it can. In the above embodiment, the estimated DPNR bed temperature is obtained from Equation 1 to simplify the calculation formula. In addition, the estimated DPNR bed temperature is estimated using a calculation formula that also considers the exhaust temperature after heat exchange, the previous estimated DPNR bed temperature, and the like. The DPNR bed temperature may be obtained. Even in that case, the detection temperature of the exhaust temperature sensor and the temperature difference between the detection temperature of the exhaust temperature sensor and the catalyst temperature are included in the calculation formula.

<Example 2>
In this embodiment, the estimated DPNR bed temperature is calculated more accurately. In the present embodiment, the characteristic part will be described, and the other configurations are the same as those in the above embodiment, and the description thereof will be omitted.

  In the present embodiment, as shown in FIG. 6, an upstream exhaust temperature sensor 14 that detects the temperature of the exhaust gas flowing into the DPNR 5 is disposed in the exhaust passage 3 immediately upstream of the DPNR 5. A downstream exhaust temperature sensor 15 that detects the temperature of the exhaust gas flowing out from the DPNR 5 is disposed in the exhaust passage 3 immediately downstream of the DPNR 5. Here, the upstream side exhaust temperature sensor 14 in this embodiment corresponds to the catalyst inflow exhaust temperature detection means of the present invention, and the downstream side exhaust temperature sensor 15 in this embodiment corresponds to the catalyst outflow exhaust temperature detection means of the present invention. . The temperature of the exhaust gas flowing into the DPNR 5 in this embodiment corresponds to the catalyst inflow exhaust temperature of the present invention, and the temperature of the exhaust gas flowing out to the DPNR 5 in the present embodiment corresponds to the catalyst outflow exhaust temperature of the present invention.

  In the first embodiment, the estimated DPNR bed temperature is calculated based on the detected temperature of the exhaust temperature sensor 7 disposed in the exhaust passage 3 immediately upstream of the DPNR 5. In the calculation of the estimated DPNR bed temperature according to the first embodiment, as shown in FIG. 7, if the upstream bed temperature and the downstream bed temperature in the exhaust flow direction of the DPNR 5 are the same constant temperature, the estimated DPNR bed temperature is determined. The temperature is equal to the actual DPNR bed temperature and the estimated DPNR bed temperature can be calculated accurately.

However, as shown in FIGS. 8A and 8B, there may be a difference (temperature gradient) between the upstream bed temperature and the downstream bed temperature in the exhaust flow direction of DPNR5. In this case, when the estimated DPNR bed temperature is calculated according to the first embodiment, since the exhaust temperature sensor 7 detects the temperature of the exhaust immediately upstream of the DPNR, the estimated DPNR bed temperature is the upstream bed temperature of the DPNR 5. In some cases, the temperature is close to the downstream temperature of the DPNR5. Here, on the downstream side of DPNR5, there is a high possibility that the bed temperature of DPNR5 is raised to a temperature higher than the allowable temperature. For this reason, it is desirable that the estimated DPNR bed temperature is calculated at a temperature closer to the downstream bed temperature than the upstream bed temperature of DPNR5.

  Therefore, in this embodiment, the estimated DPNR bed temperature (hereinafter referred to as upstream calculated estimated DPNR bed temperature) is calculated using the detected temperature detected by the upstream side exhaust temperature sensor 14, and the downstream side exhaust temperature sensor 15 detects it. The estimated DPNR bed temperature (hereinafter referred to as downstream calculation estimated DPNR bed temperature) is calculated using the detected temperature. And, the difference between the upstream bed temperature of DPNR 5 and the downstream bed temperature of DPNR immediately before the internal combustion engine 1 is automatically stopped is reflected in the reflection ratio between the upstream calculated estimated DPNR bed temperature and the downstream calculated estimated DPNR bed temperature. Thus, the DPNR bed temperature during automatic stop when the internal combustion engine 1 is automatically stopped is estimated.

  Here, the upstream side calculated estimated DPNR bed temperature is calculated in the same manner as the estimated DPNR bed temperature of the first embodiment. That is, the upstream calculation estimated DPNR bed temperature is calculated based on Equation 1 using the temperature detected by the upstream exhaust temperature sensor 14 and the automatic stop map of FIG.

  On the other hand, the downstream side calculated estimated DPNR bed temperature is calculated in the same manner as the estimated DPNR bed temperature of the first embodiment using the detected temperature of the downstream side exhaust temperature sensor 15 instead of the detected temperature of the upstream side exhaust temperature sensor 14. . That is, the downstream side calculated estimated DPNR floor temperature is obtained by using the automatic stop map indicating the temperature difference between the detected temperature of the downstream side exhaust temperature sensor 15 and the detected temperature of the downstream side exhaust temperature sensor 15 and the DPNR temperature. Calculated based on The automatic stop map used here is different from the upstream side exhaust temperature sensor 14, and is obtained in advance by experiments or the like.

  By the way, as described in the first embodiment, the estimated DPNR bed temperature during operation of the internal combustion engine 1 is calculated to be approximately equal to the actual DPNR bed temperature. Therefore, as shown in FIG. 9, the DPNR 5 is divided into four parts A part to D part from the upstream side in the exhaust flow direction, and the estimated DPNR parts (estimated part A to D part) during the operation of the internal combustion engine 1 are divided. Each bed temperature is calculated. Here, as a method of calculating the bed temperature of each part of the estimated DPNR, when the upstream side exhaust temperature sensor 14 and the downstream side exhaust temperature sensor 15 exist as in the present embodiment, the detection of the upstream side exhaust temperature sensor 14 is performed. Using the temperature and the map during operation of the internal combustion engine 1, the bed temperature of the estimated part A is calculated based on Equation 1. Further, based on the temperature detected by the downstream side exhaust temperature sensor 15 and the map during operation of the internal combustion engine 1, the bed temperature of the estimated portion D is calculated based on the equation (1). The bed temperatures of the estimated B part and C part are calculated based on the estimated bed temperatures of the estimated A part and D part.

  Since the bed temperatures of the estimated A part and D part during the operation of the internal combustion engine 1 calculated in this way are substantially equal to the actual A part bed temperature and D part bed temperature, the estimated A bed temperature is estimated as the upstream bed temperature of DPNR5. The bed temperature of the estimated D section can be used as the bed temperature downstream of the DPNR5. For this reason, the absolute value of the difference between the estimated bed temperature of the estimated A section immediately before the internal combustion engine 1 is automatically stopped and the estimated bed temperature of the estimated D section (┃ estimated A section bed temperature−estimated D section bed temperature ┃) is calculated. The reflection ratio between the upstream calculated estimated DPNR bed temperature and the downstream calculated estimated DPNR bed temperature for calculating the estimated DPNR bed temperature can be determined.

  As shown in FIG. 10, in the reflection ratio, the horizontal axis represents the absolute value of the difference between the estimated bed temperature of the estimated A section and the estimated D section immediately before the internal combustion engine 1 is automatically stopped, and the vertical axis represents the upstream Assuming that the ratio α multiplied by the side calculated estimated DPNR bed temperature is a value in the range of 0 ≦ α ≦ 1, the ratio α decreases as the absolute value increases.

Using this ratio α, the final estimated DPNR bed temperature of this example is
Estimated DPNR bed temperature = Upstream side calculated estimated DPNR bed temperature × α + Downstream side calculated estimated DPNR bed temperature × (1−α) (Equation 2)
Is calculated from

  According to the present embodiment, the larger the difference between the estimated bed temperature of the estimated A section immediately before the internal combustion engine 1 is automatically stopped and the estimated bed temperature of the estimated D section, the larger the reflection ratio of the downstream calculated estimated DPNR bed temperature can be increased. Therefore, the estimated DPNR bed temperature can be calculated at a temperature closer to the downstream bed temperature than the upstream bed temperature of DPNR 5, and the DPNR bed temperature during the automatic stop of the internal combustion engine 1 can be accurately estimated. Thereby, the learning of the fuel addition valve 6 at the time of restart of the internal combustion engine 1 and the calculation of the oxidation rate of the collected PM in the DPNR 5 are correctly performed, and the fuel efficiency is deteriorated by optimizing the execution time of the PM forced oxidation removal control. It is possible to prevent the DPNR 5 from being heated to a temperature higher than the allowable temperature.

  Next, the estimated DPNR bed temperature calculation control routine 1 during automatic stop according to the present embodiment will be described. FIG. 11 is a flowchart showing an estimated DPNR bed temperature calculation control routine 1 during automatic stop according to the present embodiment. This routine is repeatedly executed every predetermined time. The ECU 20 that executes this routine corresponds to the second catalyst bed temperature estimating means during automatic stop according to the present invention.

  In step S201, the ECU 20 calculates the upstream calculation estimated DPNR bed temperature. The upstream calculated estimated DPNR bed temperature can be obtained as in the routine of FIG. The ECU 20 that executes this step corresponds to the catalyst bed temperature estimating means during the inflow side automatic stop of the present invention.

  In step S202, the ECU 20 calculates a downstream calculation estimated DPNR bed temperature. The downstream calculated estimated DPNR bed temperature can be obtained as in the routine of FIG. 5 of the first embodiment by replacing the automatic stop map with a map corresponding to the temperature detected by the downstream exhaust temperature sensor 15. The ECU 20 that executes this step corresponds to the catalyst bed temperature estimating means during the outflow side automatic stop of the present invention.

  In step S203, the ECU 20 calculates the ratio α. The ratio α is calculated by calculating the absolute value of the difference between the estimated floor temperature of the estimated A section and the estimated floor temperature of the estimated D section immediately before the internal combustion engine 1 is automatically stopped. Can be calculated by importing into the map shown in FIG.

  In step S204, the ECU 20 calculates the estimated DPNR bed temperature based on Equation 2.

  According to this routine described above, the downstream side calculated estimated DPNR bed temperature is reflected more greatly as the difference between the bed temperature of the estimated A section immediately before the internal combustion engine 1 is automatically stopped and the bed temperature of the estimated D section is larger. The estimated DPNR bed temperature can be calculated accurately.

<Example 3>
In the present embodiment, the estimated DPNR bed temperature is calculated in consideration of the heat release amount and heat transfer amount of the DPNR 5 during the automatic stop of the internal combustion engine 1. In the present embodiment, the characteristic part will be described, and the other configurations are the same as those in the above embodiment, and the description thereof will be omitted.

  As described in the first embodiment, the estimated DPNR bed temperature is substantially equal to the actual DPNR bed temperature during operation of the internal combustion engine 1. However, during the automatic stop in which the internal combustion engine 1 is automatically stopped by the idling stop control, the estimated DPNR bed temperature has deviated from the actual DPNR bed temperature in the above estimation method.

  Therefore, in the present embodiment, the bed temperature of each part of the DPNR immediately before the internal combustion engine 1 is automatically stopped is adjacent to the heat radiation amount of each part of the DPNR during the automatic stop of the internal combustion engine 1 and during the automatic stop of the internal combustion engine 1. The amount of heat transferred between each DPNR part is added or subtracted to estimate the bed temperature of each DPNR part during the automatic stop of the internal combustion engine 1.

  By the way, as described in the first embodiment, the estimated DPNR bed temperature during operation of the internal combustion engine 1 is calculated to be approximately equal to the actual DPNR bed temperature. Therefore, as shown in FIG. 9, the DPNR 5 is divided into four parts A part to D part from the upstream side in the exhaust flow direction, and the estimated DPNR parts (estimated part A to D part) during the operation of the internal combustion engine 1 are divided. Each bed temperature is calculated. Here, as a method for calculating the bed temperature of each estimated DPNR part, when the upstream exhaust temperature sensor 14 and the downstream exhaust temperature sensor 15 are present as in the second embodiment, the detected temperature of the upstream exhaust temperature sensor 14 is detected. Then, using the map during the operation of the internal combustion engine 1, the bed temperature of the estimated part A is calculated based on Equation 1. Further, based on the temperature detected by the downstream side exhaust temperature sensor 15 and the map during operation of the internal combustion engine 1, the bed temperature of the estimated portion D is calculated based on the equation (1). The bed temperature of the estimated B part and C part is calculated based on the bed temperature of the estimated A part and D part, for example, multiplied by a ratio corresponding to the exhaust flow direction of DPNR5.

  Since the bed temperature of the estimated A part to D part during the operation of the internal combustion engine 1 calculated in this way is substantially equal to the actual A part to D part bed temperature, it is estimated as the A part to D part bed temperature of DPNR5. The bed temperature of part A to part D can be used. Accordingly, the bed temperature of the A part to the D part of the DPNR 5 immediately before the internal combustion engine 1 is automatically stopped can be accurately known.

  The amount of heat released from the A part to the D part of the DPNR 5 during the automatic stop of the internal combustion engine 1 is based on the map previously obtained through experiments or the like based on the bed temperature of the A part to the D part of the DPNR 5 immediately before the internal combustion engine 1 is automatically stopped. Calculated.

The amount of heat transfer between the A part to the D part of the adjacent DPNR 5 during the automatic stop of the internal combustion engine 1 is
Heat transfer amount = DPNR thermal conductivity / length between parts × (adjacent upstream side bed temperature−next downstream side bed temperature) × DPNR cross-sectional area × time from the start of automatic stop (Equation 3)
Is calculated from

  Here, immediately before the internal combustion engine 1 is automatically stopped, the bed temperature of the A part of the DPNR 5 is Te0a, the bed temperature of the same B part is Te0b, the bed temperature of the same C part is Te0c, and the bed temperature of the same D part is Te0d. In addition, the heat release amount t seconds after the start of the automatic stop of the internal combustion engine 1 in the A portion of the DPNR 5 is Qrta, the heat release amount in the same B portion is Qrtb, the heat release amount in the same C portion is Qrtc, and the heat release in the same D portion. Let the amount of heat be Qrtd. Further, the amount of heat transfer after t seconds from the start of automatic stop of the internal combustion engine 1 from the A part to the B part of the DPNR 5 calculated from the equation 3 is Qttab, the heat transfer amount from the same B part to the C part is Qttbc, and the same Let Qttcd be the amount of heat transfer from part C to part D.

Then, the bed temperature Teta after t seconds from the start of automatic stop of the internal combustion engine 1 in the A part of DPNR5 is
Teta = Te0a-Qrta-Qttab (Formula 4)
Is calculated from

Similarly, the bed temperature Tetb after t seconds from the start of the automatic stop of the internal combustion engine 1 in the B part of DPNR5 is
Tetb = Te0b−Qrtb−Qttbc + Qttab (Formula 5)
Is calculated from

Similarly, the bed temperature Tetc after t seconds from the start of the automatic stop of the internal combustion engine 1 in the part C of DPNR5 is
Tetc = Te0c−Qrtc−Qttcd + Qttbc (Expression 6)
Is calculated from

Similarly, the bed temperature Tetd after t seconds from the start of the automatic stop of the internal combustion engine 1 in the D part of DPNR5 is
Tetd = Te0d−Qrtd + Qttcd (Expression 7)
Is calculated from However, Qttcd is 0 in the case of a negative value.

  Therefore, according to the present embodiment, during the automatic stop of the internal combustion engine 1, the heat radiation amount of the A part to the D part of the DPNR 5 and the heat transfer amount between the A part to the D part of the adjacent DPNR 5 are accurately calculated. Thus, the estimated DPNR bed temperature during the automatic stop of the internal combustion engine 1 can be accurately calculated for each part of the A part to the D part of the DPNR 5. Thereby, the learning of the fuel addition valve 6 at the time of restart of the internal combustion engine 1 and the calculation of the oxidation rate of the collected PM in the DPNR 5 are correctly performed, and the fuel efficiency is deteriorated by optimizing the execution time of the PM forced oxidation removal control. It is possible to prevent the DPNR 5 from being heated to a temperature higher than the allowable temperature.

  Next, the estimated DPNR floor temperature calculation control routine 2 during automatic stop according to this embodiment will be described. FIG. 12 is a flowchart showing the routine for estimating DPNR bed temperature calculation control routine 2 during automatic stop according to the present embodiment. This routine is repeatedly executed every predetermined time.

  In step S301, the ECU 20 calculates the heat radiation amounts Qrta to Qrtd of the A part to the D part of the DPNR 5 during the automatic stop of the internal combustion engine 1. The amount of heat released from each part can be obtained by using a map based on the estimated bed temperatures of the parts A to D immediately before the internal combustion engine 1 is automatically stopped, which is stored in the ECU 20 in advance. The ECU 20 that executes this step corresponds to a heat release amount calculation means during automatic stop according to the present invention.

  In step S302, the ECU 20 calculates the heat transfer amounts Qtab to Qttcd between the A part to the D part of the adjacent DPNRs 5 during the automatic stop of the internal combustion engine 1. The amount of heat transfer between each part can be determined using Equation 3. The ECU 20 that executes this step corresponds to the heat transfer amount calculation means during automatic stop according to the present invention.

  In step S303, the ECU 20 calculates estimated DPNR bed temperatures Teta to Tetd for each part of the parts A to D of the DPNR 5 during the automatic stop of the internal combustion engine 1. The estimated DPNR floor temperature for each part of the A part to D part of the DPNR 5 is stored in the ECU 20 in advance, and from the estimated A part to D part bed temperatures Te0a to Te0d immediately before the internal combustion engine 1 is automatically stopped. The heat release amounts Qrta to Qrtd calculated in step S301 and the heat transfer amounts Qttab to Qttcd calculated in step S302 are calculated based on equations 4 to 7, which are added and subtracted. The ECU 20 executing this step corresponds to the third catalyst bed temperature estimating means during automatic stop according to the present invention.

  According to this routine described above, the estimated bed temperature of the A part to D part immediately before the internal combustion engine 1 is automatically stopped, the heat radiation amount of the A part to D part of the DPNR 5 during the automatic stop of the internal combustion engine 1, and the internal combustion engine The estimated DPNR bed temperature can be accurately calculated for each part of the A part to the D part of the DPNR 5 from the heat transfer amount between the A part to the D part of the adjacent DPNR 5 during the automatic stop of the engine 1.

  The automatic stop / restart device for an internal combustion engine according to the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention.

1 is a diagram showing a schematic configuration of an internal combustion engine and an intake system / exhaust system thereof according to Embodiment 1. FIG. A map of the temperature difference between the detected temperature of the exhaust temperature sensor and the DPNR temperature during operation of the internal combustion engine. The figure which shows the correlation of the detection temperature of an exhaust temperature sensor and the DPNR floor temperature during the automatic stop of an internal combustion engine. A map of the temperature difference between the detected temperature of the exhaust temperature sensor and the DPNR temperature during the automatic stop of the internal combustion engine. 6 is a flowchart showing an estimated DPNR bed temperature calculation control routine according to the first embodiment. FIG. 3 is a diagram illustrating a schematic configuration of an internal combustion engine and an intake system and an exhaust system thereof according to a second embodiment. The figure which shows the DPNR floor temperature of constant temperature in the DPNR exhaust flow direction in the case of an automatic stop of an internal combustion engine. The figure which shows DPNR floor temperature with a temperature gradient in the DPNR exhaust flow direction in the case of an automatic stop of an internal combustion engine. The figure which shows the state which divided DPNR into the A part-D part from the upstream in the exhaust flow direction. The figure which shows the correlation with the absolute value of the difference of the estimated A part bed temperature just before the automatic stop of an internal combustion engine, and the estimated D part bed temperature, and the ratio (alpha). 7 is a flowchart showing an estimated DPNR floor temperature calculation control routine 1 during automatic stop according to a second embodiment. FIG. 9 is a flowchart illustrating an estimated DPNR floor temperature calculation control routine 2 during automatic stop according to a third embodiment.

Explanation of symbols

1 Internal combustion engine 2 Intake passage 3 Exhaust passage 4 Air flow meter 5 DPNR
6 Fuel addition valve 7 Exhaust temperature sensor 8 Fuel injection valve 9 Starter motor 10 Accelerator opening sensor 11 Brake opening sensor 12 Crank position sensor 13 Vehicle speed sensor 14 Upstream exhaust temperature sensor 15 Downstream exhaust temperature sensor 20 ECU

Claims (3)

Automatic control means for automatically stopping the internal combustion engine when the automatic stop condition is satisfied and automatically restarting the internal combustion engine when the automatic restart condition is satisfied;
A catalyst disposed in an exhaust passage of the internal combustion engine for purifying exhaust;
A near-catalyst exhaust temperature detecting means that is disposed in an exhaust passage near the catalyst and detects a near-catalyst exhaust temperature;
While the automatic control means automatically stops the internal combustion engine, the automatic stop that represents the exhaust temperature near the catalyst detected by the exhaust gas temperature detecting means near the catalyst and the temperature difference between the exhaust gas temperature near the catalyst and the catalyst temperature A first automatic stop catalyst bed temperature estimating means for estimating the catalyst bed temperature based on
An automatic stop / restart device for an internal combustion engine. Automatic control means for automatically stopping the internal combustion engine when the automatic stop condition is satisfied and automatically restarting the internal combustion engine when the automatic restart condition is satisfied;
A catalyst disposed in an exhaust passage of the internal combustion engine for purifying exhaust;
A catalyst inflow exhaust gas temperature detection means for detecting a catalyst inflow exhaust gas temperature disposed in an exhaust passage immediately upstream of the catalyst;
A catalyst outflow exhaust temperature detecting means disposed in an exhaust passage immediately downstream of the catalyst and detecting a catalyst outflow exhaust temperature;
An inflow side representing a catalyst inflow / exhaust temperature detected by the catalyst inflow / exhaust temperature detection means and a temperature difference between the catalyst inflow / exhaust temperature and the catalyst temperature during the automatic stop when the internal combustion engine is automatically stopped by the automatic control means An automatic stop map; and an inflow-side automatic stop catalyst bed temperature estimating means for estimating the catalyst bed temperature based on the map;
The outflow side representing the catalyst outflow exhaust temperature detected by the catalyst outflow exhaust temperature detection means and the temperature difference between the catalyst outflow exhaust temperature and the catalyst temperature during the automatic stop when the internal combustion engine is automatically stopped by the automatic control means An automatic stop map, and an outflow side automatic stop catalyst bed temperature estimating means for estimating the catalyst bed temperature based on the map,
The automatic control means sets the reflection ratio between the catalyst bed temperature estimated by the inflow-side automatic stop catalyst bed temperature estimation means and the catalyst bed temperature estimated by the outflow-side automatic stop catalyst bed temperature estimation means. Change according to the difference between the catalyst upstream bed temperature and the catalyst downstream bed temperature immediately before the engine is automatically stopped, and the automatic control means estimates the catalyst bed temperature during the automatic stop when the internal combustion engine is automatically stopped. A second catalyst bed temperature estimating means during automatic stop;
An automatic stop / restart device for an internal combustion engine. Automatic control means for automatically stopping the internal combustion engine when the automatic stop condition is satisfied and automatically restarting the internal combustion engine when the automatic restart condition is satisfied;
A catalyst disposed in an exhaust passage of the internal combustion engine for purifying exhaust;
A heat release amount calculation means during automatic stop for calculating a heat release amount of each part of the catalyst divided into a plurality of parts in the exhaust flow direction during the automatic stop when the automatic control means automatically stops the internal combustion engine;
An automatic stop heat transfer amount calculating means for calculating the heat transfer amount between the adjacent parts of the catalyst that are automatically stopped by the automatic control means automatically stopping the internal combustion engine;
The automatic control means automatically calculates the heat release amount calculated by the heat release amount calculation means during automatic stop and the heat transfer amount calculated by the heat transfer amount calculation means during automatic stop to the bed temperature of each part of the catalyst immediately before the internal combustion engine is automatically stopped. A catalyst bed temperature estimating means during automatic stop for estimating the bed temperature of each part of the catalyst during automatic stop in which the automatic control means automatically stops the internal combustion engine;
An automatic stop / restart device for an internal combustion engine.

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