JP2009293409A - Catalyst temperature estimating device and catalyst temperature estimating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further accurately estimate the temperature of a purifying catalyst of an internal combustion engine equipped with an exhaust gas supply means capable of supplying an intake system with exhaust gas according to the opening of an exhaust gas supply valve. <P>SOLUTION: A coefficient k is set based on a preceding Tcat and a future temperature T* of the catalyst set based on an intake air quantity Ga to an engine and the target step number Ns* of a stepping motor for opening an EGR valve (S230). A temperature variation ΔTegr per unit time after the EGR valve is opened is set based on the actual step number Ns obtained by applying first-order lag processing to the target step number Ns* (S250). A present temperature Tcat is estimated by adding the temperature variation ΔTegr to a temperature variation ΔT per unit time based on the state of the engine and a three-way catalyst, multiplying the added value by the coefficient k, and adding the multiplied value to the preceding Tcat (S260). The temperature of the purifying catalyst can thereby be estimated to gradually approach the future temperature T* with a first-order lag processing curve. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a catalyst temperature estimation device and a catalyst temperature estimation method, and more particularly, to an exhaust gas supply means capable of supplying exhaust gas to an intake system according to the opening degree of the exhaust gas supply valve, and the exhaust gas supply valve based on a target opening degree. The present invention relates to a catalyst temperature estimation device and a catalyst temperature estimation method that are provided in an internal combustion engine that includes an exhaust gas supply control means that controls the exhaust gas and a purification catalyst that purifies exhaust gas, and that estimates the temperature of the purification catalyst.

Conventionally, as a device for grasping the temperature of a purification catalyst of an internal combustion engine provided with an exhaust gas recirculation (EGR) device that supplies exhaust gas to an intake system, a device that directly detects the catalyst temperature by a temperature sensor attached to the purification catalyst has been proposed. (For example, refer to Patent Document 1).
JP 2006-118358 A

  By the way, the device for grasping the temperature of the purification catalyst is not limited to the one that is directly detected as described above, and there is one that estimates the catalyst temperature based on the amount of intake air taken into the internal combustion engine. The estimated catalyst temperature is used, for example, to determine whether or not the purification catalyst has reached a predetermined activation temperature. When it is determined that the purification catalyst has reached, diagnosis of deterioration of the purification catalyst may be performed. Here, in the case of judging the deterioration of the purification catalyst based on the oxygen storage amount of the catalyst, the oxygen storage amount also changes depending on the catalyst temperature. Therefore, if it is erroneously determined that the activation temperature has been reached, the deterioration of the purification catalyst Cannot be determined correctly. For this reason, it is required to accurately estimate the catalyst temperature. Further, in an internal combustion engine equipped with an EGR device as described above, even if the EGR valve is controlled at the target opening, there is a delay until the EGR valve opens, or the exhaust gas is actually discharged from the start of the valve opening. Since there is a delay before it is introduced into the cylinder of the engine, it may be difficult to accurately estimate the catalyst temperature based on the target opening.

  The catalyst temperature estimation device and the catalyst temperature estimation method according to the present invention more accurately estimate the temperature of a purification catalyst of an internal combustion engine including an exhaust gas supply unit capable of supplying exhaust gas to an intake system according to the opening of an exhaust gas supply valve. The main purpose.

  The catalyst temperature estimation apparatus and the catalyst temperature estimation method of the present invention employ the following means in order to achieve the above-described main object.

The catalyst temperature estimation device of the present invention is
Exhaust supply means capable of supplying exhaust to the intake system according to the opening of the exhaust supply valve, exhaust supply control means for controlling the exhaust supply valve based on the target opening, and a purification catalyst for purifying the exhaust A catalyst temperature estimation device provided in an internal combustion engine for estimating the temperature of the purification catalyst,
Intake air amount detection means for detecting the amount of intake air taken into the intake system of the internal combustion engine;
Future temperature setting means for setting a future temperature of the purification catalyst based on the detected intake air amount and the target opening;
The present invention includes a current temperature estimating means for estimating a current temperature of the purification catalyst so as to gradually approach the set future temperature with a first-order lag processing curve.

  In this catalyst temperature estimation device of the present invention, the exhaust supply means capable of supplying exhaust to the intake system according to the opening of the exhaust supply valve, the exhaust supply control means for controlling the exhaust supply valve based on the target opening, and the exhaust The future temperature of the purification catalyst is set based on the amount of intake air sucked into the intake system of the internal combustion engine and the target opening degree, and the purification catalyst is gradually purified with a first-order lag processing curve. The current temperature of the purification catalyst is estimated so as to approach. Here, the temperature of the purification catalyst of the internal combustion engine provided with the exhaust supply means is affected by a delay in the operation of the exhaust supply valve, a delay in the inflow of exhaust, and the like, and does not immediately converge to the future temperature. Such a delay in the operation of the exhaust supply valve and the inflow of exhaust can be approximated as a first-order lag process, and the temperature of the purification catalyst changes to a curve like a first-order lag process with respect to the future temperature. Applicant has made it clear through experiments. Therefore, a value close to the actual temperature can be estimated by estimating the current temperature of the purification catalyst so as to gradually approach the future temperature with a first-order lag processing curve. As a result, it is possible to more accurately estimate the temperature of the purification catalyst of the internal combustion engine provided with the exhaust supply means capable of supplying exhaust to the intake system according to the opening of the exhaust supply valve.

  In such a catalyst temperature estimation device of the present invention, the current temperature estimation means may be means for estimating the current temperature so that the slope of the curve becomes gentler as the actual opening of the exhaust supply valve increases. it can. Here, since the flow rate of the exhaust gas supplied to the intake system increases as the opening degree of the exhaust supply valve increases, the influence of the delay of the inflow of exhaust gas becomes larger than when the opening degree is small. Therefore, by estimating the current temperature so that the slope of the curve becomes gentler as the actual opening increases, the catalyst temperature can be estimated in consideration of the effect of the larger actual opening.

  Further, in the catalyst temperature estimating device of the present invention, the current temperature estimating means is configured to set the future with respect to a temperature change amount per unit time determined to increase as the actual opening of the exhaust supply valve increases. It can also be a means for estimating the current temperature by adding to the current temperature estimated the previous time, a product obtained by multiplying a coefficient determined by a tendency to increase as the deviation between the temperature and the current temperature estimated last time increases. .

  Furthermore, in the catalyst temperature estimation device of the present invention, the actual opening can be estimated by performing a first-order lag process on the target opening of the exhaust supply valve. In this way, the catalyst temperature can be accurately estimated even if the actual opening is delayed with respect to the target opening due to the delay of the operation of the exhaust supply valve.

The catalyst temperature estimation method of the present invention includes:
An internal combustion engine comprising exhaust supply means capable of supplying exhaust gas to the intake system according to the opening of the exhaust supply valve, exhaust supply control means for controlling the exhaust supply valve based on a target opening, and a purification catalyst for purifying the exhaust A catalyst temperature estimation method for estimating the temperature of the purification catalyst,
(A) setting a future temperature of the purification catalyst based on an intake air amount sucked into an intake system of the internal combustion engine and the target opening;
(B) The gist is to estimate the present temperature of the purification catalyst so as to gradually approach the set future temperature with a first-order lag processing curve.

  According to the catalyst temperature estimation method of the present invention, the exhaust supply means that can supply exhaust gas to the intake system according to the opening of the exhaust supply valve, and the exhaust supply control means that controls the exhaust supply valve based on the target opening The future temperature of the purification catalyst is set based on the amount of intake air sucked into the intake system of the internal combustion engine including the purification catalyst for purifying the exhaust gas and the target opening, and the curve is like a first order lag process to the set future temperature. The current temperature of the purification catalyst is estimated so as to approach gradually. Here, the temperature of the purification catalyst of the internal combustion engine provided with the exhaust supply means is affected by a delay in the operation of the exhaust supply valve, a delay in the inflow of exhaust, and the like, and does not immediately converge to the future temperature. Such a delay in the operation of the exhaust supply valve and the inflow of exhaust can be approximated as a first-order lag process, and the temperature of the purification catalyst changes to a curve like a first-order lag process with respect to the future temperature. Applicant has made it clear through experiments. Therefore, a value close to the actual temperature can be estimated by estimating the current temperature of the purification catalyst so as to gradually approach the future temperature with a first-order lag processing curve. As a result, it is possible to more accurately estimate the temperature of the purification catalyst of the internal combustion engine provided with the exhaust supply means capable of supplying exhaust to the intake system according to the opening of the exhaust supply valve.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 20 equipped with an engine 22 including a catalyst temperature estimation device as an embodiment of the present invention, and FIG. FIG.

  As shown in FIG. 1, the hybrid vehicle 20 according to the embodiment includes an engine 22, an engine electronic control unit (hereinafter referred to as an engine ECU) 24 that controls the operation of the engine 22, and a crankshaft 26 of the engine 22 on a carrier. Is coupled to the drive wheels 63a and 63b via a differential gear 38 and a planetary gear having a ring gear coupled to a drive shaft 37 and a sun gear of the power distribution and integration mechanism 30. A motor MG1 capable of generating electricity connected to the motor, a motor MG2 capable of generating and outputting power to the drive shaft 37, inverters 41 and 42 as drive circuits for the motors MG1 and MG2, and power to the inverters 41 and 42 And a hybrid that controls the entire vehicle. And an electronic control unit 70 for driving, the power from the engine 22 is torque-converted by the power distribution and integration mechanism 30 and the two motors MG1 and MG2 with charging / discharging of the battery 50, and output to the drive shaft 37 to travel. In the state where the operation of the engine 22 is stopped, the motive power output from the motor MG2 is output to the drive shaft 37 by the electric power from the battery 50 and travels.

  The engine 22 is configured as an internal combustion engine capable of outputting power using a hydrocarbon-based fuel such as gasoline or light oil, and the air purified by an air cleaner 122 is passed through a throttle valve 124 as shown in FIG. Inhalation and gasoline are injected from the fuel injection valve 126 to mix the sucked air and gasoline. The mixture is sucked into the fuel chamber through the intake valve 128 and is explosively burned by an electric spark from the spark plug 130. Thus, the reciprocating motion of the piston 132 pushed down by the energy is converted into the rotational motion of the crankshaft 26. Exhaust gas from the engine 22 is discharged to the outside air through a purification device 134 (three-way catalyst 134a) that purifies harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx).

  The three-way catalyst 134a of the purifier 134 is composed of an oxidation catalyst such as platinum (Pt) or palladium (Pd), a reduction catalyst such as rhodium (Rh), and a promoter such as ceria (CeO2). When activated at a temperature higher than a predetermined activation temperature, CO and HC contained in the exhaust gas are purified to water (H2O) and carbon dioxide (CO2) by the action of the oxidation catalyst, and are contained in the exhaust gas by the action of the reduction catalyst. NOx is purified to nitrogen (N2) or oxygen (O2). Here, CeO2 has the property that the valence of cerium (Ce) changes reversibly between trivalent and tetravalent, so when the exhaust is in a lean atmosphere, it changes from trivalent to tetravalent and from the exhaust. Oxygen is occluded, and when the exhaust is in a rich atmosphere, it changes from tetravalent to trivalent and releases oxygen to the exhaust. Further, an oxygen sensor 135b is installed at the subsequent stage of the purification device 134. The oxygen sensor 135b has an output value that changes depending on whether the exhaust is rich or lean. In the embodiment, the zirconia electrolyte is sandwiched between a reference electrode that contacts the atmosphere and a measurement electrode that contacts the exhaust. A zirconia oxygen sensor that generates an electromotive force according to the difference in oxygen concentration is employed. Since the zirconia electrolyte is an insulator at normal temperature, it is necessary to reach a predetermined activation temperature in order to operate the oxygen sensor 135b normally.

  An EGR pipe 152 that supplies exhaust gas to the intake side is attached to the rear stage of the purification device 134, and the engine 22 supplies exhaust gas as non-combustion gas to the intake side to generate a mixture of air, exhaust gas, and gasoline. It can be sucked into the combustion chamber. The amount of exhaust gas supplied to the intake side of the engine 22 is adjusted by an EGR valve 154 driven by a stepping motor 153 as an actuator. Hereinafter, supplying the exhaust of the engine 22 to the intake side is referred to as EGR. FIG. 3 is a flowchart showing an example of an EGR control routine executed by the engine ECU 24. This routine is repeatedly executed every predetermined time (for example, every several msec). In the EGR control routine, the CPU 24a of the engine ECU 24 inputs data necessary for control such as the rotational speed Ne of the engine 22 and the load factor kl (step S100), and sets the input rotational speed Ne of the engine 22 and the load factor kl. Based on this, the target step number Ns * of the stepping motor 153 is set (step S110), the stepping motor 153 is driven and controlled with the set target step number Ns * (step S120), and this routine is finished. In setting the target step number Ns *, in the embodiment, the relationship among the rotational speed Ne of the engine 22, the load factor kl, and the target step number Ns * is obtained in advance and stored in the ROM 24b as a target step number setting map. When the rotation speed Ne and the load factor kl are given, the corresponding target step number Ns * is derived from the target step number setting map. An example of this map is shown in FIG. As shown in the figure, the target step number Ns * is 0 (EGR off) when the load factor kl and the rotational speed Ne are not within the exhaust introduction region in the figure, and when the load factor kl and the rotation speed Ne are within the exhaust introduction region, The rotation speed Ne is set so as to increase as it goes to a higher load and higher rotation speed. The EGR valve 154 opens with a larger opening as the number of steps driven by the stepping motor 153 increases. However, the stepping motor 153 has a limited number of steps that operate in a unit time, and the target step number Ns * is set. In practice, however, the stepping motor 153 is driven by a predetermined number of steps toward the target number of steps Ns *. Therefore, a certain amount of time is required until the actual step number of the stepping motor 153 (hereinafter, the actual step number Ns) reaches the target step number Ns *.

  The engine ECU 24 is configured as a microprocessor centered on the CPU 24a, and includes a ROM 24b that stores a processing program, a RAM 24c that temporarily stores data, an input / output port and a communication port (not shown), in addition to the CPU 24a. . The engine ECU 24 receives signals from various sensors that detect the state of the engine 22, for example, a crank position from the crank position sensor 140 that detects the rotational position of the crankshaft 26, and a water temperature that detects the temperature of cooling water in the engine 22. The temperature of the coolant from the sensor 142, the intake valve 128 that performs intake and exhaust to the combustion chamber, the cam position from the cam position sensor 144 that detects the rotational position of the camshaft that opens and closes the exhaust valve, and the throttle valve that detects the position of the throttle valve 124 The throttle position from the position sensor 146, the intake air amount Ga from the air flow meter 148 attached to the intake pipe, the intake air temperature from the temperature sensor 149 also attached to the intake pipe, the air-fuel ratio sensor 135a attached to the exhaust pipe Air-fuel ratio of, are inputted similarly as oxygen signal from an attached oxygen sensor 135b in the exhaust pipe via the input port. The engine ECU 24 also integrates various control signals for driving the engine 22, such as a drive signal to the fuel injection valve 126, a drive signal to the throttle motor 136 that adjusts the position of the throttle valve 124, and an igniter. The control signal to the ignition coil 138, the control signal to the variable valve timing mechanism 150 that can change the opening / closing timing of the intake valve 128, the drive signal to the stepping motor 153 that adjusts the opening degree of the EGR valve 154, and the like are output. It is output through the port. The engine ECU 24 is in communication with the hybrid electronic control unit 70, controls the operation of the engine 22 by a control signal from the hybrid electronic control unit 70, and outputs data related to the operation state of the engine 22 as necessary. . The engine ECU 24 calculates the rotation speed of the crankshaft 26 based on the crank position from the crank position sensor 140, that is, the rotation speed Ne of the engine 22, or the intake air amount from the air flow meter 148 with respect to the maximum intake air amount Gamax. The load factor kl as a proportion of Ga is calculated.

  Here, the air flow meter 148 and the engine ECU 24 correspond to the hardware configuration of the catalyst temperature estimation device that estimates the temperature of the three-way catalyst 134a in the engine 22.

  Next, the operation of the catalyst temperature estimation device that estimates the temperature of the three-way catalyst 134a configured as described above will be described. FIG. 5 is a flowchart showing an example of a catalyst temperature estimation processing routine executed by the engine ECU 24. This routine is repeatedly executed every predetermined time (for example, every several tens of msec).

  When the catalyst temperature estimation processing routine is executed, the CPU 24a of the engine ECU 24 first inputs necessary data such as the intake air amount Ga from the air flow meter 148 and the target step number Ns * of the stepping motor 153 (step S200). The future temperature Tcat * of the three-way catalyst 134a is set based on the input intake air amount Ga and the target step number Ns * (step S210). Here, as for the future temperature Tcat *, in the embodiment, the relationship among the intake air amount Ga, the target step number Ns *, and the future temperature Tcat * is obtained in advance and stored in the ROM 24b as a future temperature setting map. Given Ga and the target step number Ns *, the corresponding future temperature Tcat * is derived from the map and set. An example of this map is shown in FIG. As shown in the figure, the future temperature Tcat * is set so as to increase as the intake air amount Ga increases, and is set to decrease as the target step number Ns * increases. The larger the target step number Ns * is, the lower the setting is. The larger the opening degree of the EGR valve 154, the more the inert gas having a large heat capacity contained in the exhaust gas is supplied to the engine 22, By lowering the combustion temperature.

  When the future temperature Tcat * is set, the temperature deviation Td is calculated as an absolute value obtained by subtracting the current temperature (previous Tcat) of the three-way catalyst 134a estimated when the routine was previously executed from the set future temperature Tcat *. Then, the coefficient k is set based on the calculated temperature deviation Td (step S230). Here, in the embodiment, in the embodiment, the relationship between the temperature deviation Td and the coefficient k is obtained in advance and stored in the ROM 24b as a coefficient setting map. When the temperature deviation Td is given, the corresponding coefficient k is derived from the map. And set it. An example of this map is shown in FIG. As illustrated, the coefficient k is set to increase as the temperature deviation Td increases.

  When the coefficient k is set, the target step number Ns * is subjected to first-order lag processing to calculate the actual step number Ns of the stepping motor 153 (step S240). Since the first-order lag processing is a well-known technique, its description is omitted. When the actual step number Ns is calculated, a temperature change amount ΔTegr per unit time given to the three-way catalyst 134a after the EGR valve 154 is opened is set based on the calculated actual step number Ns (step S250). Here, in the embodiment, the temperature change amount ΔTegr is obtained in advance as a relationship between the actual step number Ns and the temperature change amount ΔTegr and stored in the ROM 24b as a temperature change amount setting map, and the actual step number Ns is given. The corresponding temperature change amount ΔTegr is derived from the map and set. An example of this map is shown in FIG. As shown in the figure, the temperature change amount ΔTegr is set to a value of 0 when the actual step number Ns is 0, and is set to a smaller value (a larger value as an absolute value) as the actual step number Ns is larger. Here, even if the EGR valve 154 is opened, the exhaust does not immediately flow into the engine 22, but there is a delay in the actual exhaust flow, and this delay can be approximated as a first-order delay process. it can. Then, the applicant has clarified through experiments and the like that the actual temperature change of the three-way catalyst 134a converges into a first-order delay processing curve due to the delay of the inflow of the exhaust gas. Further, the larger the opening degree (actual number of steps Ns) of the EGR valve 154, the larger the inflow amount of exhaust gas, and the greater the influence that can be caused by the inflow delay of exhaust gas. growing. For this reason, as the opening degree of the EGR valve 154 increases, the gradient of the temperature change becomes gentle, that is, the value of the time constant in the first-order lag processing curve increases. As described above, since the influence on the temperature change given to the three-way catalyst 134a after the EGR valve 154 is opened depends on the actual step number Ns, the temperature change amount ΔTegr is represented in a map as shown in FIG. It is set based on this.

  When the temperature change amount ΔTegr is set, the temperature change amount ΔT per unit time given to the three-way catalyst 134a is calculated according to the state of the engine 22 and the three-way catalyst 134a, and the temperature change amount ΔTegr is added from the calculated temperature change amount ΔT. The current temperature Tcat is estimated by adding the product of the coefficient k to the previous Tcat (step S260), and this routine is terminated. Here, the temperature change amount ΔT is, for example, a temperature change amount due to combustion exhaust based on the intake air amount Ga sucked into the engine 22, a temperature change amount due to heat radiation from the purification device 134 to the outside, or the three-way catalyst 134a itself. It can be determined by calculating the amount of temperature change due to heat of reaction. The temperature change amount ΔT is calculated in the same manner when the EGR valve 154 is closed. By adding the temperature change amount ΔTegr to such a temperature change amount ΔT, the temperature of the three-way catalyst 134a is estimated in consideration of the influence of the temperature change amount ΔTegr, that is, the influence after the EGR valve 154 is opened. Will be. Here, as described above, as the opening degree (actual step number Ns) of the EGR valve 154 increases, the temperature change amount ΔTegr decreases toward the negative side (the absolute value increases). Therefore, the temperature change amount ΔTegr is added to the temperature change amount ΔT. The value obtained by adding is small. For this reason, the current temperature Tcat tends to be estimated to be smaller as the actual step number Ns is larger.

  FIG. 9 is an explanatory diagram showing an example of the temperature transition of the current temperature Tcat estimated by the catalyst temperature estimation processing routine of the present embodiment, which is large when the opening degree (target step number Ns *) of the EGR valve 154 is small. The case is illustrated. In both cases, the future temperature Tcat * was set to the same temperature. As shown in the figure, the current temperature Tcat is estimated with a first-order lag processing curve, and the slope of the curve approaching the future temperature Tcat * becomes gentler as the target step number Ns * increases. That is, the time constant in the first-order lag process changes according to the opening degree (target step number Ns *) of the EGR valve 154, and the current temperature Tcat is estimated so that the temperature change becomes gentle.

  The current temperature Tcat of the three-way catalyst 134a thus estimated is used, for example, to determine whether or not the temperature of the three-way catalyst 134a reaches or exceeds a predetermined catalyst activation temperature. Execution of deterioration determination, abnormality determination of the oxygen sensor 135b, etc. is permitted. In the embodiment, the deterioration determination of the three-way catalyst 134a is performed based on the measurement result of the maximum oxygen storage amount of the three-way catalyst 134a. Here, since the maximum oxygen storage amount depends on the temperature of the three-way catalyst 134a, when the three-way catalyst 134a does not actually reach the predetermined activation temperature, the deterioration of the three-way catalyst 134a may be erroneously determined. However, in the embodiment, since the current temperature Tcat of the three-way catalyst 134a can be accurately estimated, the possibility of erroneous determination is reduced. Further, the abnormality determination of the oxygen sensor 135b is performed based on the oxygen concentration detected in a state where the fuel cut to the engine 22 is performed in the embodiment. As described above, the oxygen sensor 135b does not operate normally unless the predetermined activation temperature is reached. However, in the embodiment, the oxygen sensor 135b is brought to the activation temperature using the accurately estimated temperature of the three-way catalyst 134a. It is possible to determine whether or not the oxygen sensor has reached, and the risk of erroneous determination of the oxygen sensor 135b is reduced.

  According to the hybrid vehicle 20 of the embodiment described above, the future temperature T * and the previous Tcat of the three-way catalyst 134a set based on the intake air amount Ga to the engine 22 and the target step number Ns * of the stepping motor 153 The coefficient k is set based on the temperature deviation Td, and the temperature change amount ΔTegr per unit time after the EGR valve 154 is opened based on the actual step number Ns obtained by performing the first order lag processing on the target step number Ns *. And the temperature change amount ΔTgr per unit time calculated based on the state of the engine 22 and the three-way catalyst 134a is added to the previous Tcat by adding the temperature change amount ΔTegr and multiplied by the coefficient k to obtain the current temperature Tcat. By estimating, the current temperature Tcat is estimated so as to gradually approach the set future temperature T * with a first-order lag processing curve. It is possible. As a result, the temperature of the three-way catalyst 134a of the engine 22 that can supply exhaust gas to the intake system can be estimated more accurately according to the opening of the EGR valve 154.

  In the hybrid vehicle 20 of the embodiment, the actual step number Ns is calculated by performing the first-order lag process on the target step number Ns *. However, the present invention is not limited to this. For example, the driving from the engine ECU 24 to the stepping motor 153 is performed. The number of pulses output as a signal may be stored, and the actual step number Ns may be grasped based on the number of pulses.

  In the hybrid vehicle 20 of the embodiment, the temperature deviation Td between the future temperature T * of the three-way catalyst 134a and the previous Tcat set based on the intake air amount Ga to the engine 22 and the target step number Ns * of the stepping motor 153 is set. Based on the actual step number Ns obtained by performing the first-order lag process on the target step number Ns *, the temperature change amount ΔTegr per unit time after the EGR valve 154 is opened is set. The temperature change amount ΔTgr per unit time calculated based on the states of the 22 and the three-way catalyst 134a and the temperature change amount ΔTegr multiplied by the coefficient k are added to the previous Tcat to estimate the current temperature Tcat. However, when the time constant τ is set so as to increase as the target step number Ns * of the stepping motor 153 increases, The first-order lag processing using the number τ may to estimate the current temperature Tcat of the three-way catalyst 134a by performing.

  In the hybrid vehicle 20 of the embodiment, the power of the motor MG2 is changed by the reduction gear 35 and output to the ring gear shaft 32a. However, as illustrated in the hybrid vehicle 120 of the modification of FIG. May be connected to an axle (an axle connected to the wheels 64a and 64b in FIG. 10) different from an axle to which the ring gear shaft 32a is connected (an axle to which the drive wheels 63a and 63b are connected).

  In the hybrid vehicle 20 of the embodiment, the power of the engine 22 is output to the ring gear shaft 32a as the drive shaft connected to the drive wheels 63a and 63b via the power distribution and integration mechanism 30, but the modified example of FIG. The hybrid vehicle 220 includes an inner rotor 232 connected to the crankshaft 26 of the engine 22 and an outer rotor 234 connected to a drive shaft that outputs power to the drive wheels 63a and 63b. A counter-rotor motor 230 that transmits a part of the power to the drive shaft and converts the remaining power into electric power may be provided.

  Further, the present invention is not limited to those applied to such a hybrid vehicle, and as long as an internal combustion engine is provided, an engine 22, an automatic transmission (AT) 330, as shown in a modified vehicle 320 in FIG. It is good also as what is applied to a normal motor vehicle provided with, and it does not matter as a form of the catalyst temperature estimation apparatus of the purification catalyst provided in internal combustion engines other than a motor vehicle. Moreover, it is good also as a form of a catalyst temperature estimation method.

  Here, the correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the engine 22 corresponds to an “internal combustion engine”, the EGR pipe 152, the stepping motor 153, and the EGR valve 154 correspond to “exhaust supply means”, and are based on the rotational speed Ne of the engine 22 and the load factor kl. The engine ECU 24 that sets the target step number Ns * of the stepping motor 153 and executes the EGR control routine of FIG. 3 for driving and controlling the stepping motor 153 with the set target step number Ns * corresponds to “exhaust supply control means”. The air flow meter 148 attached to the intake pipe corresponds to “intake air amount detection means”, and the three-way catalyst is based on the intake air amount Ga detected by the air flow meter 148 and the target step number Ns * of the stepping motor 153. The catalyst temperature estimation processing routine of FIG. 5 for setting the future temperature Tcat * of 134a The engine ECU 24 that executes the processes of steps S200 and S210 corresponds to “future temperature setting means”, sets a coefficient k based on the temperature deviation Td between the future temperature T * and the previous Tcat, and is primary to the target step number Ns *. A unit time calculated based on the state of the engine 22 and the three-way catalyst 134a is set by setting a temperature change amount ΔTegr per unit time after the EGR valve 154 is opened based on the actual step number Ns subjected to the delay process. The process of steps S220 to S260 of the catalyst temperature estimation processing routine of FIG. 5 is performed in which the current temperature Tcat is estimated by adding the temperature change amount ΔTgr to the pertinent temperature change amount ΔT and multiplying by the coefficient k and adding to the previous Tcat. The engine ECU 24 corresponds to “current temperature setting means”. Here, the “internal combustion engine” is not limited to an internal combustion engine that outputs power using a hydrocarbon fuel such as gasoline or light oil, and may be any type of internal combustion engine such as a hydrogen engine. The “exhaust supply means” is composed of the EGR pipe 152, the stepping motor 153, and the EGR valve 154. However, any means can be used as long as exhaust can be supplied to the intake system according to the opening of the exhaust supply valve. It does n’t matter. As the “exhaust supply control means”, the target step number Ns * of the stepping motor 153 is set based on the rotational speed Ne of the engine 22 and the load factor kl, and the stepping motor 153 is driven and controlled with the set target step number Ns *. However, the present invention is not limited to this, and any device that controls the exhaust supply valve based on the target opening degree may be used. The “intake air amount detection means” is not limited to the air flow meter 148, and includes a sensor that detects a physical amount related to the intake air amount and an engine ECU 24 that calculates the intake air amount based on the detected signal. Any combination may be used as long as it can detect the intake air amount. The “future temperature setting means” is limited to one that sets the future temperature Tcat * of the three-way catalyst 134a based on the intake air amount Ga detected by the air flow meter 148 and the target step number Ns * of the stepping motor 153. The present invention is not limited to this, and any device that sets the future temperature of the purification catalyst based on the detected intake air amount and the target opening of the exhaust supply valve may be used. As the “current temperature setting means”, a coefficient k is set based on the temperature deviation Td between the future temperature T * and the previous Tcat, and EGR is performed based on the actual step number Ns obtained by subjecting the target step number Ns * to the first-order lag processing. The temperature change amount ΔTegr per unit time after the valve 154 is opened is set, and the temperature change amount ΔTegr is added to the temperature change amount ΔT per unit time calculated based on the states of the engine 22 and the three-way catalyst 134a. The current temperature of the purification catalyst is not limited to the value obtained by multiplying the coefficient k by the previous Tcat and estimating the current temperature Tcat, but gradually approaches the set future temperature with a first-order lag processing curve. Any method may be used as long as it can be estimated. The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems is the same as that of the embodiment described in the column of means for solving the problems. It is an example for specifically explaining the best mode for doing so, and does not limit the elements of the invention described in the column of means for solving the problems. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  The best mode for carrying out the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it can be implemented in the form.

  The present invention is applicable to the automobile industry and the like.

1 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 20 according to an embodiment of the present invention. 2 is a configuration diagram showing an outline of a configuration of an engine 22. FIG. It is a flowchart which shows an example of the EGR control routine performed by engine ECU24 of an Example. It is explanatory drawing which shows an example of the map for target step number setting. It is a flowchart which shows an example of the catalyst temperature estimation process routine performed by engine ECU24 of an Example. It is explanatory drawing which shows an example of the map for future temperature setting. It is explanatory drawing which shows an example of the map for a coefficient setting. It is explanatory drawing which shows an example of the map for temperature variation setting. It is explanatory drawing which shows an example of the temperature transition of the present temperature Tcat estimated by the catalyst temperature estimation process routine of a present Example. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 120 according to a modification. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 220 of a modified example. It is a block diagram which shows the outline of a structure of the motor vehicle 320 of a modification.

Explanation of symbols

  20, 120, 220 Hybrid vehicle, 22 engine, 24 engine electronic control unit (engine ECU), 24a CPU, 24b ROM, 24c RAM, 26 crankshaft, 30 power distribution and integration mechanism, 37 drive shaft, 38 differential gear, 41 , 42 Inverter, 50 Battery, 63a, 63b Drive wheel, 64a, 64b Wheel, 70 Hybrid electronic control unit, 122 Air cleaner, 124 Throttle valve, 126 Fuel injection valve, 128 Intake valve, 130 Spark plug, 132 Piston, 134 Purification Equipment, 134a three-way catalyst, 135a air-fuel ratio sensor, 135b oxygen sensor, 136, throttle motor, 138 ignition coil, 140 crank position sensor, 1 2 Water temperature sensor, 144 Cam position sensor, 146 Throttle valve position sensor, 148 Air flow meter, 149 Temperature sensor, 150 Variable valve timing mechanism, 152 EGR pipe, 153 Stepping motor, 154 EGR valve, 230 Counter rotor motor, 232 Inner rotor 234 Outer rotor, 320 automobile, 330 automatic transmission, MG1, MG2 motor.

Claims (5)

Exhaust supply means capable of supplying exhaust to the intake system according to the opening of the exhaust supply valve, exhaust supply control means for controlling the exhaust supply valve based on the target opening, and a purification catalyst for purifying the exhaust A catalyst temperature estimation device provided in an internal combustion engine for estimating the temperature of the purification catalyst,
Intake air amount detection means for detecting the amount of intake air taken into the intake system of the internal combustion engine;
Future temperature setting means for setting a future temperature of the purification catalyst based on the detected intake air amount and the target opening;
A current temperature estimating means for estimating a current temperature of the purification catalyst so as to gradually approach the set future temperature with a first-order lag processing curve;
A catalyst temperature estimation device comprising:   The catalyst temperature estimating device according to claim 1, wherein the current temperature estimating means is a means for estimating the current temperature so that the slope of the curve becomes gentler as the actual opening of the exhaust supply valve increases.   The current temperature estimating means is a deviation between the set future temperature and the previously estimated current temperature with respect to a temperature change amount per unit time determined to increase as the actual opening of the exhaust supply valve increases. The catalyst temperature estimation apparatus according to claim 1 or 2, which is a means for estimating a current temperature by adding a product obtained by multiplying a coefficient determined to a tendency to increase with increasing to a current temperature estimated last time.   4. The catalyst temperature estimating apparatus according to claim 2, wherein the current temperature estimating means is means for estimating an actual opening by performing a first-order delay process on a target opening of the exhaust supply valve. An internal combustion engine comprising exhaust supply means capable of supplying exhaust gas to an intake system in accordance with the opening of the exhaust supply valve, exhaust supply control means for controlling the exhaust supply valve based on a target opening, and a purification catalyst for purifying the exhaust A catalyst temperature estimation method for estimating the temperature of the purification catalyst,
(A) setting a future temperature of the purification catalyst based on an intake air amount sucked into an intake system of the internal combustion engine and the target opening;
(B) A catalyst temperature estimation method for estimating the present temperature of the purified catalyst so as to gradually approach the set future temperature with a first-order lag processing curve.

Images