JP2006037921A - Exhaust system part temperature estimating device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately estimate the temperatures of exhaust system parts according to a fuel injection system without using a temperature sensor in an internal combustion engine switchable between an intake pipe injection and a cylinder injection. <P>SOLUTION: For each of the intake pipe injection and the cylinder injection, a converging temperature map specifying a relation between engine operating conditions (such as engine speed, and intake air volume or fuel injection volume) and the converging temperature of the exhaust system parts is stored in the ROM of an ECU, and during the operation of the engine, the converging temperature map according to a present fuel injection system stored in the ROM is retrieved to provide the converging temperatures of the exhaust parts according to the present fuel injection system and the engine operating conditions (steps 101 to 103). After that, the converging temperatures are filter-treated (annealing treatment, primary delay treatment) with a temperature variation time constant according to the operating conditions of the engine to provide the estimated temperatures of the exhaust system parts (steps 104 and 105). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine that estimates the temperature of an exhaust system component provided in an exhaust passage of an internal combustion engine that includes a fuel injection valve that injects fuel into an intake pipe and a fuel injection valve that injects fuel into a cylinder. The invention relates to an exhaust system component temperature estimation device.

  In an exhaust passage of an internal combustion engine mounted on a vehicle, exhaust system parts such as a catalyst for purifying exhaust gas and an exhaust gas sensor are provided. Since these exhaust system parts are exposed to high-temperature exhaust gas exhausted from the internal combustion engine, a certain degree of temperature rise is inevitable.However, if the exhaust system part temperature exceeds the allowable upper limit temperature, parts deterioration or failure may occur. For this reason, it is desirable to control the temperature of the exhaust gas so that the temperature of the exhaust system parts is kept below the allowable upper limit temperature. In order to realize this control, it is necessary to monitor the temperature of the exhaust system parts by some method. For this reason, if a temperature sensor for detecting the temperature of the exhaust system parts is provided, the number of sensors increases, There is a drawback of high cost.

Therefore, as described in Patent Document 1 (Japanese Patent No. 3262157), the catalyst temperature is monitored without using a temperature sensor by estimating the catalyst temperature based on the engine rotation speed and the intake pipe pressure. There is something like that.
Japanese Patent No. 3262157 ([0033] to [0035] etc.)

  Fuel injection systems for internal combustion engines are broadly classified into intake pipe injection (intake port injection) for injecting fuel into an intake pipe (intake port) and in-cylinder injection for injecting fuel into a cylinder. In recent years, fuel injection valves have been installed on the intake pipe (intake port) and the upper part of the cylinder, respectively, and by switching between intake pipe injection and in-cylinder injection according to the operating conditions of the internal combustion engine, low fuel consumption, high output, and reduced exhaust emissions There is something that has been realized. In such an internal combustion engine, even if the engine speed is the same, if the fuel injection method is different, the temperature of the exhaust gas and the flow rate of the exhaust gas are different, and the amount of temperature rise of the exhaust system parts is different.

  The catalyst temperature estimation technique of Patent Document 1 described above is a catalyst temperature estimation technique in an intake pipe injection engine. However, when this catalyst temperature estimation technique is applied to an internal combustion engine that can switch the fuel injection system, the fuel injection system is different. However, if the engine speed is the same, the catalyst temperature is estimated to be the same, and the catalyst temperature cannot be estimated with high accuracy.

  The present invention has been made in view of such circumstances. Therefore, the object of the present invention is not to use a temperature sensor in an internal combustion engine capable of switching the fuel injection system, but to adjust the exhaust system components according to the fuel injection system. An object of the present invention is to provide an exhaust system component temperature estimation device for an internal combustion engine capable of accurately estimating the temperature.

  In order to achieve the above object, an invention according to claim 1 is an internal combustion engine comprising a fuel injection valve that performs intake pipe injection for injecting fuel into an intake pipe, and a fuel injection valve that injects fuel into a cylinder. The exhaust system temperature estimating means for estimating the temperature of the exhaust system component based on the operating condition of the internal combustion engine switches the method for estimating the temperature of the exhaust system component according to the current fuel injection method, and changes the temperature of the exhaust system component. Is to be estimated. In this way, when the fuel injection method is switched, the exhaust gas temperature and the exhaust gas flow rate change, and the temperature rise of the exhaust system component changes to estimate the temperature of the exhaust system component. Since the method is switched, the temperature of the exhaust system component can be accurately estimated according to the fuel injection method without using a temperature sensor.

  Specifically, as in claim 2, a convergence temperature map that defines the relationship between the operating condition of the internal combustion engine and the convergence temperature of the exhaust system parts for each fuel injection system is stored in the storage means, and the internal combustion engine is stored. During the operation of the engine, the convergence temperature map corresponding to the current fuel injection method stored in the storage means is searched, and the convergence temperature of the exhaust system parts according to the current fuel injection method and the operating condition of the internal combustion engine is obtained. Then, the estimated temperature of the exhaust system component may be obtained by filtering the convergence temperature with a predetermined temperature change time constant. Here, the “convergence temperature” is a temperature that finally becomes constant during steady operation where the operating conditions do not change. In general, the operating conditions often change before the temperature of the exhaust system components reaches the convergence temperature, and the convergence temperature differs before and after the change of the operating conditions. Actually, since it takes some time for the temperature of the exhaust system parts to reach the convergence temperature corresponding to the changed operating conditions after the operating conditions have changed, in the present invention, the temperature of the exhaust system parts is time-consuming. The behavior of the temperature change until the convergence temperature is reached with a delay is regarded as a temperature change with a delay such as a first-order lag, and the convergence temperature corresponding to the current operating condition is filtered with a predetermined temperature change time constant (an annealing process, The temperature of the exhaust system component is estimated by performing a first-order lag process or the like, thereby improving the estimation accuracy of the exhaust system component temperature.

  According to a third aspect of the present invention, there is provided a convergence temperature map that defines the relationship between the operating conditions of the internal combustion engine and the convergence temperature of exhaust system parts for a specific fuel injection system, and the specific fuel injection system and other fuel injection systems. A temperature difference map that defines the relationship between the difference in convergence temperature between the engine and the operating condition of the internal combustion engine is stored in storage means, and the convergence temperature map stored in the storage means during operation of the internal combustion engine To determine the convergence temperature of the exhaust system parts according to the current operating conditions of the internal combustion engine in the specific fuel injection method, and if the current fuel injection method is different from the specific fuel injection method, the temperature difference The map is searched to obtain a temperature difference according to the current operating condition of the internal combustion engine, the convergence temperature in the specific fuel injection method is corrected based on this temperature difference, and the convergence temperature is filtered by a predetermined temperature change time constant. It may be obtained the estimated temperature of the exhaust system component by. In this case, when the current fuel injection method is a specific fuel injection method, it is not necessary to correct the convergence temperature using the temperature difference map.

  In addition, as in claim 4, two types of convergence temperature maps that define the relationship between the operating conditions of the internal combustion engine and the convergence temperatures of the exhaust system parts for the intake pipe injection and the in-cylinder injection are stored in the storage means. In addition, during the operation of the internal combustion engine, the two types of convergence temperature maps stored in the storage means are searched, and the exhaust system parts corresponding to the current operating conditions of the internal combustion engine for intake pipe injection and in-cylinder injection, respectively. The final convergence temperature is obtained by interpolating and correcting these two convergence temperatures according to the injection ratio of the current intake pipe injection and in-cylinder injection. The estimated temperature of the exhaust system parts may be obtained by filtering with a constant. In this case, there is an advantage that the convergence temperature can be calculated using two types of convergence temperature maps regardless of how the injection ratio of the intake pipe injection and the in-cylinder injection changes.

  Alternatively, as in claim 5, the storage means stores a convergence temperature map that defines the relationship between the injection ratio of the intake pipe injection and the in-cylinder injection, the operating conditions of the internal combustion engine, and the convergence temperature of the exhaust system components. The exhaust temperature according to the operating condition of the internal combustion engine at the current injection ratio of the intake pipe injection and the in-cylinder injection is searched by searching the convergence temperature map stored in the storage means during the operation of the internal combustion engine. An estimated temperature of the exhaust system part may be obtained by obtaining a convergence temperature of the system part and filtering the convergence temperature with a predetermined temperature change time constant. In this way, the convergence temperature corresponding to the operating condition of the internal combustion engine at the current injection ratio of the intake pipe injection and the in-cylinder injection can be obtained by searching only one convergence temperature map.

  By the way, the exhaust gas temperature and the exhaust gas flow rate (the amount of exhaust heat flowing around the exhaust system parts) change depending on the operating conditions of the internal combustion engine, so the delay time until the exhaust system part temperature reaches the convergence temperature (that is, the temperature change) (Time constant) varies depending on the operating conditions of the internal combustion engine. Considering this point, a temperature change time constant map that defines the relationship between the operating condition of the internal combustion engine and the temperature change time constant is stored in the storage means, and the internal combustion engine is operating. The temperature change time constant map stored in the storage means is searched to obtain a temperature change time constant according to the current operating condition of the internal combustion engine, and the convergence temperature is filtered by this temperature change time constant. It is preferable to obtain the estimated temperature of the exhaust system parts. In this way, the temperature change time constant can be changed in response to changes in the exhaust gas temperature and the exhaust gas flow rate depending on the operating conditions of the internal combustion engine, so that the appropriate temperature according to the operating conditions of the internal combustion engine can be obtained. The temperature change time constant can be set, and the estimation accuracy of the exhaust system component temperature can be further improved. However, in the present invention, in order to simplify the arithmetic processing, the temperature change time constant map may be omitted and the temperature change time constant may be set to a constant value.

  The exhaust system component that is the target of temperature estimation may be a catalyst or exhaust gas sensor for purifying exhaust gas (Claim 7), or other exhaust system component (for example, an exhaust turbine).

  According to another aspect of the present invention, when the estimated temperature of the exhaust system component reaches a predetermined upper limit temperature, the fuel injection amount may be corrected to be increased by the injection amount correction means. The increase correction of the fuel injection amount has an effect of lowering the temperature of the exhaust gas, and the temperature of the exhaust system parts can be suppressed to a predetermined upper limit temperature or less.

  Hereinafter, four Examples 1 to 4 embodying the best mode for carrying out the present invention will be described.

  A first embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 driven by a motor 15 such as a DC motor is provided on the downstream side of the air flow meter 14, and an opening degree (throttle opening degree) of the throttle valve 16 is detected by a throttle opening degree sensor 17.

  A surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and the intake manifold 20 for each cylinder is provided with a fuel injection valve 21 for injecting fuel into the intake port. Yes.

  A fuel injection valve 22 that directly injects fuel into each cylinder is attached to the upper part of the cylinder of the engine 11. A spark plug 23 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by the spark discharge of each spark plug 23.

  A cooling water temperature sensor 24 or the like for detecting the cooling water temperature is attached to the cylinder block of the engine 11. A crank angle sensor 25 that outputs a crank angle signal at every predetermined crank angle is attached to the outer peripheral side of the crankshaft (not shown). Based on the output signal of the crank angle sensor 25, the crank angle and the engine speed are detected.

  On the other hand, the exhaust pipe 26 of the engine 11 is provided with a catalyst 27 for purifying exhaust gas, and an exhaust gas sensor 28 (air-fuel ratio sensor) for detecting the air-fuel ratio or rich / lean of the exhaust gas is provided upstream of the catalyst 27. , Oxygen sensors, etc.).

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and executes various control routines stored in a built-in ROM (storage medium), thereby changing the fuel injection method according to the engine operating conditions and the fuel in the intake port. While switching to one of intake pipe injection (intake port injection) by the injection valve 21 and in-cylinder injection by the fuel injection valve 22 at the upper part of the cylinder, the fuel injection amount, injection timing, ignition timing, and the like are controlled.

  Further, the ECU 30 estimates the temperature of the exhaust system component (the catalyst 27 or the exhaust gas sensor 28) by executing an exhaust system component temperature estimation routine of FIG. Here, the exhaust system component temperature estimation method of the first embodiment will be described.

  For the intake pipe injection and the in-cylinder injection, a convergence temperature map that defines the relationship between the engine operating conditions and the convergence temperature of the exhaust system parts is stored in a ROM (storage means) that is a nonvolatile memory of the ECU 30, and the engine operation is performed. The convergence temperature map corresponding to the current fuel injection method stored in the ROM is searched to determine the convergence temperature of the exhaust system parts according to the current fuel injection method and the engine operating conditions. Is subjected to filter processing (smoothing processing, first-order lag processing, etc.) with a predetermined temperature change time constant to obtain the estimated temperature of the exhaust system parts. Here, the “convergence temperature” is a temperature that finally becomes constant during steady operation where the engine operating conditions do not change. In general, the engine operating conditions often change before the temperature of the exhaust system parts reaches the convergence temperature, and the convergence temperature differs before and after the change of the engine operating conditions. Actually, since it takes some time for the temperature of the exhaust system parts to reach the convergence temperature corresponding to the engine operating condition after the change after the engine operating conditions change, the exhaust system parts in the first embodiment. The temperature change behavior until the temperature reaches the convergence temperature with a time delay is regarded as a temperature change with a delay such as a primary delay, and the convergence temperature corresponding to the current engine operating conditions is filtered with a predetermined temperature change time constant (Smoothing process, first-order lag process, etc.) are used for estimation.

  By the way, the exhaust gas temperature and the exhaust gas flow rate (the amount of exhaust heat flowing around the exhaust system parts) change depending on the engine operating conditions, so the delay time until the exhaust system part temperature reaches the convergence temperature (that is, the temperature change time constant) Varies depending on engine operating conditions. In consideration of this point, in the first embodiment, a temperature change time constant map that defines the relationship between the engine operating conditions and the temperature change time constant is stored in the ROM of the ECU 30 and stored in the ROM during engine operation. The temperature change time constant map is searched to obtain a temperature change time constant according to the current engine operating condition, and the convergence temperature is filtered by this temperature change time constant, so that the estimated temperature of the exhaust system parts Asking for. In this way, the temperature change time constant can be changed in response to changes in the exhaust gas temperature and the exhaust gas flow rate depending on the engine operating conditions, and the appropriate temperature change time constant corresponding to the engine operating conditions can be changed. Can be set.

  In this case, the engine operating condition used as a parameter of the convergence temperature map or the temperature change time constant map may be any factor that changes the exhaust gas flow rate or the exhaust gas temperature. For example, the engine rotation speed, the intake air amount ( Alternatively, the fuel injection amount), air-fuel ratio, cooling water temperature, outside air temperature, vehicle speed (cooling effect by traveling wind), ignition timing, etc. may be selected. In the first embodiment, the engine rotational speed, the intake air amount (or fuel injection amount), the convergence temperature map, and the temperature change time constant map that have a great influence on the exhaust gas flow rate and the exhaust gas temperature are used.

  The estimation of the exhaust system temperature of the first embodiment described above is executed by the ECU 30 according to the exhaust system component temperature estimation routine of FIG. This routine is executed at a predetermined cycle during engine operation, and serves as exhaust system temperature estimation means in the claims. When this routine is started, first, at step 101, it is determined whether or not the current fuel injection method is intake pipe injection. If it is intake pipe injection, the routine proceeds to step 102 and is stored in the ROM of the ECU 30. A convergence temperature map for intake pipe injection is searched, and a convergence temperature of exhaust system components corresponding to the current engine speed and intake air amount (or fuel injection amount) in intake pipe injection is calculated. On the other hand, if it is determined in step 101 that the in-cylinder injection is performed, the process proceeds to step 103, where a convergence temperature map for in-cylinder injection stored in the ROM of the ECU 30 is searched, and the current engine speed in the in-cylinder injection. And the convergence temperature of the exhaust system parts according to the intake air amount (or fuel injection amount). At this time, considering that the higher the engine rotation speed and the larger the intake air amount (or fuel injection amount), the higher the exhaust gas flow rate and the higher the exhaust heat amount, the convergence temperature map is calculated based on the engine rotation speed. The convergence temperature of the exhaust system parts is set to be higher as the speed is higher and as the intake air amount (or fuel injection amount) is increased.

  As described above, after the convergence temperature of the exhaust system parts is calculated in step 102 or 103, the process proceeds to step 104, the temperature change time constant map stored in the ROM of the ECU 30 is searched, and the current engine speed is calculated. A temperature change time constant according to the speed and the intake air amount (or fuel injection amount) is calculated. Thereafter, the routine proceeds to step 105, where the convergence temperature is filtered using the temperature change time constant (smoothing process, first-order lag process, etc.), thereby calculating the estimated temperature of the exhaust system parts and ending this routine. .

  The temperature correction routine shown in FIG. 3 is executed by the ECU 30 in synchronism with the calculation timing of the fuel injection amount, and serves as injection amount correction means in the claims. When this routine is started, first, in step 111, it is determined whether or not the estimated temperature of the exhaust system component calculated in the exhaust system component temperature estimation routine is equal to or higher than a predetermined upper limit temperature, and the exhaust system component is estimated. If the temperature is lower than the upper limit temperature, it is determined that correction of the fuel injection amount is unnecessary, and this routine ends.

  On the other hand, if it is determined in step 111 that the estimated temperature of the exhaust system component is equal to or higher than the upper limit temperature, the process proceeds to step 112, the fuel injection amount is increased and the routine is terminated. By correcting the fuel injection amount to be increased, the temperature of the exhaust gas is lowered, so that the temperature of the exhaust system parts can be suppressed to the upper limit temperature or less.

  According to the first embodiment described above, when the fuel injection method is switched, the temperature of the exhaust gas and the flow rate of the exhaust gas change, and the temperature rise amount of the exhaust system component changes. Therefore, the temperature of the exhaust system parts can be accurately estimated according to the fuel injection method without using a temperature sensor.

  Moreover, in the first embodiment, the temperature change time constant when filtering the convergence temperature of the exhaust system parts is set according to the engine operating conditions, so the exhaust gas temperature and exhaust gas flow rate depend on the engine operating conditions. As the temperature changes, the temperature change time constant can be changed, and an appropriate temperature change time constant according to the engine operating conditions can be set.

  In the first embodiment, as the temperature change time constant map, the same map is used for the intake pipe injection and the in-cylinder injection, but the temperature change time constant map for the intake pipe injection and the in-cylinder injection are used. And a temperature change time constant map corresponding to the fuel injection method may be selected from the two temperature change time constant maps.

  Of course, the present invention may omit the temperature change time constant map and set the temperature change time constant to a constant value in order to simplify the arithmetic processing.

  In the first embodiment, the convergence temperature map is provided for each of the intake pipe injection and the in-cylinder injection. However, in the second embodiment of the present invention shown in FIG. 4, either the intake pipe injection or the in-cylinder injection is selected. As a specific fuel injection method, a convergence temperature map is provided only for this specific fuel injection method, and the relationship between the difference in convergence temperature between the specific fuel injection method and other fuel injection methods and the engine operating conditions are specified. The temperature difference map to be stored is stored in the ROM of the ECU 30, and the convergence temperature map stored in the ROM is searched during engine operation, and the exhaust system according to the current engine operating condition in the specific fuel injection method If the current fuel injection method is different from a specific fuel injection method, the temperature difference corresponding to the current engine operating condition is obtained by searching the temperature difference map. The convergence temperature in the particular fuel injection system corrects the time difference, and to obtain the estimated temperature of the exhaust system components by filtering the convergence temperature at a predetermined temperature change time constant.

  The above-described estimation of the exhaust system temperature of the second embodiment is executed by the ECU 30 as follows according to the exhaust system component temperature estimation routine of FIG. In this routine, the intake pipe injection is a “specific fuel injection method”.

  When this routine is started, first, in step 201, regardless of the current fuel injection method, the intake pipe injection convergence temperature map stored in the ROM of the ECU 30 is searched, and the current in the intake pipe injection is searched. A convergence temperature Tp of the exhaust system component corresponding to the engine speed and the intake air amount (or fuel injection amount) is calculated. Thereafter, the process proceeds to step 202, where it is determined whether or not the current fuel injection system is intake pipe injection (specific fuel injection system). If it is determined that the intake pipe injection is performed, the convergence temperature calculated in step 201 is determined. Tp is used as it is.

On the other hand, if it is determined in step 202 that the in-cylinder injection is performed, the process proceeds to step 203 where a temperature difference map stored in the ROM of the ECU 30 is searched to search for the current engine speed and intake air amount (or A temperature difference ΔT corresponding to the fuel injection amount) is calculated. Thereafter, the process proceeds to step 204, where the convergence temperature Tp calculated in step 201 is corrected by the temperature difference ΔT calculated in step 203 to determine the convergence temperature Td in in-cylinder injection.
Td = Tp + ΔT

  After calculating the convergence temperature (Tp or Td) of the exhaust system parts as described above, the process proceeds to step 205, the temperature change time constant is calculated by the same method as in Example 1, and then the process proceeds to step 206. By filtering the convergence temperature (Tp or Td) using this temperature change time constant, the estimated temperature of the exhaust system parts is calculated, and this routine ends.

  In the second embodiment described above, the same effect as that of the first embodiment can be obtained.

  In the third embodiment of the present invention shown in FIG. 5, a convergence temperature map that defines the relationship between the engine operating conditions and the convergence temperature of exhaust system parts is stored in the ROM of the ECU 30 for intake pipe injection and in-cylinder injection, respectively. The two kinds of convergence temperature maps are searched during engine operation, and the convergence temperatures of the exhaust system parts corresponding to the current engine operating conditions are obtained for the intake pipe injection and the in-cylinder injection, respectively. The final convergence temperature is obtained by interpolation correction according to the injection ratio between the intake pipe injection and the in-cylinder injection, and this convergence temperature is filtered by a predetermined temperature change time constant to estimate the exhaust system part temperature. Asking for.

  The estimation of the exhaust system temperature in the third embodiment is executed by the ECU 30 according to the exhaust system component temperature estimation routine of FIG. First, in step 301, a convergence temperature map for intake pipe injection stored in the ROM of the ECU 30 is searched, and exhaust according to the current engine speed and intake air quantity (or fuel injection quantity) in the intake pipe injection. A convergence temperature Tp of the system part is calculated. Thereafter, the routine proceeds to step 302, where a convergence temperature map for in-cylinder injection stored in the ROM of the ECU 30 is searched, and according to the current engine rotation speed and intake air amount (or fuel injection amount) in in-cylinder injection. The convergence temperature Td of the exhaust system parts is calculated.

  Thereafter, the process proceeds to step 303, where the final convergence temperature is obtained by interpolating and correcting the two convergence temperatures Tp and Td in accordance with the injection ratio of the current intake pipe injection and in-cylinder injection. Thereafter, the process proceeds to step 304, and the temperature change time constant is calculated by the same method as in the first embodiment. Then, the process proceeds to step 305, and the convergence temperature is filtered using the temperature change time constant, so that the exhaust gas is exhausted. The estimated temperature of the system part is calculated, and this routine ends.

  The third embodiment described above has an advantage that the convergence temperature can be calculated using two types of convergence temperature maps regardless of how the injection ratio of the intake pipe injection and the in-cylinder injection changes.

  In the fourth embodiment of the present invention shown in FIG. 6, the relationship between the injection ratio of intake pipe injection and in-cylinder injection, engine operating conditions (engine speed and intake air amount or fuel injection amount), and the convergence temperature of exhaust system components. Is stored in the ROM of the ECU 30. Then, when the exhaust system component temperature estimation routine of FIG. 6 is started, first, in step 401, a convergence temperature map stored in the ROM of the ECU 30 is searched, and the current engine speed and intake air amount (or The convergence temperature of the exhaust system parts according to the fuel injection amount) and the injection ratio is calculated. Thereafter, the process proceeds to step 402, the temperature change time constant is calculated by the same method as in the first embodiment, and then the process proceeds to step 403, where the convergence temperature is filtered using the temperature change time constant, thereby exhausting. The estimated temperature of the system part is calculated, and this routine ends.

  The fourth embodiment has an advantage that the convergence temperature corresponding to the engine operating condition in the current injection ratio of the intake pipe injection and the in-cylinder injection can be obtained only by searching one convergence temperature map.

  In the system configuration example of FIG. 1, the fuel injection valve 21 is provided in the intake manifold 20 of each cylinder. However, a fuel injection valve may be provided in the collective intake passage on the upstream side of the intake manifold 20.

  In addition to the catalyst 27 and the exhaust gas sensor 28, the exhaust system component that is the target of temperature estimation may be, for example, an exhaust turbine.

It is a schematic block diagram of the whole engine control system in Example 1 of this invention. 6 is a flowchart illustrating a flow of processing of an exhaust system component temperature estimation routine according to the first embodiment. It is a flowchart which shows the flow of a process of a temperature correction routine. 6 is a flowchart illustrating a flow of processing of an exhaust system component temperature estimation routine according to a second embodiment. 12 is a flowchart illustrating a flow of processing of an exhaust system component temperature estimation routine according to a third embodiment. FIG. 10 is a flowchart illustrating a processing flow of an exhaust system component temperature estimation routine according to a fourth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 20 ... Intake manifold, 21 ... Fuel injection valve for intake pipe injection, 22 ... Fuel injection valve for intake pipe injection, 23 ... Spark plug, 26 ... exhaust pipe, 27 ... catalyst (exhaust system part), 28 ... exhaust gas sensor (exhaust system part), 30 ... ECU (exhaust system temperature estimating means, injection amount correcting means)

Claims (8)

A fuel injection valve that performs intake pipe injection that injects fuel into the intake pipe and a fuel injection valve that injects fuel into the cylinder, and the fuel injection method is one of intake pipe injection, in-cylinder injection, or both In an internal combustion engine that operates by switching,
Exhaust system temperature estimating means for estimating the temperature of exhaust system parts provided in the exhaust passage of the internal combustion engine based on operating conditions of the internal combustion engine,
The exhaust system temperature estimation means estimates an exhaust system component temperature by switching a method for estimating the temperature of the exhaust system component according to a current fuel injection system, and estimates an exhaust system component temperature of the internal combustion engine apparatus. Storage means for storing a convergence temperature map that defines the relationship between the operating conditions of the internal combustion engine and the convergence temperature of the exhaust system parts for each fuel injection method;
The exhaust system temperature estimating means searches the convergence temperature map corresponding to the current fuel injection method stored in the storage means during operation of the internal combustion engine, and sets the current fuel injection method and the operating condition of the internal combustion engine. 2. The internal combustion engine according to claim 1, wherein a convergence temperature of the exhaust system component is obtained and an estimated temperature of the exhaust system component is obtained by filtering the convergence temperature with a predetermined temperature change time constant. Exhaust system part temperature estimation device. A convergence temperature map that defines the relationship between the operating conditions of the internal combustion engine and the convergence temperature of the exhaust system parts for a specific fuel injection system, and the difference in convergence temperature between the specific fuel injection system and another fuel injection system Storage means for storing a temperature difference map that defines the relationship between the engine and the operating conditions of the internal combustion engine,
The exhaust system temperature estimation means searches the convergence temperature map stored in the storage means during operation of the internal combustion engine, and the exhaust gas according to the current operating condition of the internal combustion engine in the specific fuel injection method If the current fuel injection method is different from the specific fuel injection method, the temperature difference map is searched to obtain the temperature difference according to the current operating condition of the internal combustion engine. 2. The estimated temperature of the exhaust system component is obtained by correcting a convergence temperature in the specific fuel injection method based on the difference and filtering the convergence temperature with a predetermined temperature change time constant. Apparatus for estimating temperature of exhaust system parts of an internal combustion engine. Storage means for storing two types of convergence temperature maps that define the relationship between the operating conditions of the internal combustion engine and the convergence temperatures of the exhaust system parts for the intake pipe injection and the in-cylinder injection,
The exhaust system temperature estimating means searches the two kinds of convergence temperature maps stored in the storage means during operation of the internal combustion engine, and the current operating conditions of the internal combustion engine for intake pipe injection and in-cylinder injection, respectively. The convergence temperature of the exhaust system component corresponding to the above is obtained, and the final convergence temperature is obtained by interpolating and correcting these two convergence temperatures according to the injection ratio of the current intake pipe injection and in-cylinder injection. The exhaust system component temperature estimation device according to claim 1, wherein the estimated temperature of the exhaust system component is obtained by filtering the temperature with a predetermined temperature change time constant. Storage means for storing a convergence temperature map that defines the relationship between the injection ratio of intake pipe injection and in-cylinder injection, the operating conditions of the internal combustion engine, and the convergence temperature of the exhaust system parts;
The exhaust system temperature estimation means searches the convergence temperature map stored in the storage means during operation of the internal combustion engine, and operates the internal combustion engine operating conditions at the current injection ratio of intake pipe injection and in-cylinder injection. 2. The internal combustion engine according to claim 1, wherein a convergence temperature of the exhaust system component in accordance with the engine temperature is obtained, and the estimated temperature of the exhaust system component is obtained by filtering the convergence temperature with a predetermined temperature change time constant. Engine exhaust system part temperature estimation device. The storage means stores a temperature change time constant map that defines the relationship between operating conditions of the internal combustion engine and the temperature change time constant;
The exhaust system temperature estimating means searches the temperature change time constant map stored in the storage means during operation of the internal combustion engine to obtain a temperature change time constant according to the current operating condition of the internal combustion engine, 6. The exhaust system component temperature estimating apparatus for an internal combustion engine according to claim 2, wherein the estimated temperature of the exhaust system component is obtained by filtering the convergence temperature with a temperature change time constant.   The exhaust system component temperature estimating device for an internal combustion engine according to any one of claims 1 to 6, wherein the exhaust system component is a catalyst or an exhaust gas sensor for purifying exhaust gas.   The internal combustion engine according to any one of claims 1 to 7, further comprising injection amount correction means for correcting an increase in fuel injection amount when an estimated temperature of the exhaust system component reaches a predetermined upper limit temperature. Exhaust system part temperature estimation device.

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