electronic control device

Abstract

The present invention precisely estimates the temperature of a catalyst (EHC). An electronic control device of the present invention is used to control an engine system including an internal combustion engine, an electric motor capable of driving the internal combustion engine, a catalyst for purifying exhaust gas, which is provided in an exhaust passage of the internal combustion engine, has a function of being heated by power supply, and a downstream temperature sensor provided downstream of the catalyst. The electronic control device includes a control section that drives the internal combustion engine using the electric motor, and an estimation section capable of executing a first estimation process in which the temperature of the catalyst is estimated based on detection information of the downstream temperature sensor when the internal combustion engine is driven.

Description

Technical Field

[0001] This invention relates to electronic control devices. Background Technology

[0002] Internal combustion engines contain a catalyst in their exhaust pipe to purify exhaust gases. When the engine is first started, the catalyst temperature is sometimes low, and at low temperatures, it cannot function effectively. Therefore, unpurified exhaust gases may be released into the atmosphere immediately after the engine starts. Furthermore, the catalyst temperature cannot be maintained when the engine stops. Thus, even in hybrid vehicles, there is a problem where the engine cannot be stopped to maintain the catalyst temperature.

[0003] Therefore, in order to maintain the catalyst temperature even when the internal combustion engine is not in use, researchers are studying the use of an electrically heated catalyst (EHC) that can be heated by supplying an electric current. Patent Document 1 discloses a control system for an EHC. The EHC control system disclosed in Patent Document 1 is based on the premise that the resistance value of the EHC is temperature-dependent, and uses the resistance value obtained from the voltage and current when energized to control the temperature of the EHC.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-229978 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] However, depending on the material, the resistance value of an EHC may change only slightly with temperature variations. Therefore, when measurement errors in voltage or current or fluctuations in characteristics occur, it becomes difficult to determine the temperature of the EHC based solely on its resistance value.

[0009] The present invention was made in view of the above-mentioned situation, and its purpose is to estimate the temperature of EHC with high accuracy.

[0010] Technical means to solve the problem

[0011] To address the aforementioned problems and achieve the objectives of this invention, the present invention provides an electronic control device for controlling an engine system, the engine system comprising: an internal combustion engine; an electric motor capable of driving the internal combustion engine; a catalyst for purifying exhaust gases, disposed in the exhaust passage of the internal combustion engine and having the function of being heated by an electric power supply; and a downstream temperature sensor disposed downstream of the catalyst. The electronic control device includes: a control unit that drives the internal combustion engine using the electric motor; and an estimation unit capable of performing a first estimation process, in which the temperature of the catalyst is estimated based on detection information from the downstream temperature sensor when the internal combustion engine is driven.

[0012] Invention Effects

[0013] The electronic control device based on the described structure can accurately estimate the temperature of the EHC.

[0014] Furthermore, the technical issues, technical features, and technical effects other than those mentioned above will become clear through the following description of the embodiments. Attached Figure Description

[0015] Figure 1 This is a schematic structural diagram of the entire system controlled by the electronic control device according to one embodiment of the present invention.

[0016] Figure 2 This is a diagram illustrating a structural example of the functional modules of an electronic control device according to an embodiment of the present invention.

[0017] Figure 3 This is a block diagram illustrating an example of the hardware structure of an electronic control device according to an embodiment of the present invention.

[0018] Figure 4 It is a graph showing the correlation between catalyst temperature T and catalyst resistance R (temperature-resistance characteristic).

[0019] Figure 5 This is a flowchart illustrating an example of the processing performed when the power is turned on in an electronic control device.

[0020] Figure 6 This is a graph illustrating the estimation of EHC temperature based on the previous final estimate and ECU downtime.

[0021] Figure 7 This is a flowchart illustrating an example of a process performed periodically by an electronic control device according to an embodiment of the present invention.

[0022] Figure 8 This is a flowchart illustrating an example of EHC temperature estimation processing performed by an electronic control device according to an embodiment of the present invention.

[0023] Figure 9It is a graph illustrating the relationship between intake air temperature, downstream EHC temperature, and EHC temperature.

[0024] Figure 10 This is a flowchart illustrating an example of EHC power-on control processing performed by an electronic control device according to an embodiment of the present invention.

[0025] Figure 11 This is a diagram illustrating the operation of EHC temperature control performed by an electronic control device according to one embodiment of the present invention (one of the diagrams).

[0026] Figure 12 This is a diagram (second one) illustrating the operation of EHC temperature control performed by the electronic control device according to one embodiment of the present invention.

[0027] Figure 13 This is a diagram (third one) illustrating the operation of EHC temperature control performed by the electronic control device according to an embodiment of the present invention. Detailed Implementation

[0028] 1. Implementation Method

[0029] The following is for reference Figures 1-12 An electronic control device according to one embodiment of the present invention will be described. Common components are labeled with the same reference numerals in all figures.

[0030] [System structure of the controlled object of the electronic control device]

[0031] First, a structural example of the entire engine system, which is the object of control of the electronic control device according to one embodiment of the present invention, will be described.

[0032] Figure 1 It is a schematic diagram of the entire system that is controlled by the electronic control device.

[0033] The system controlled by the electronic control device includes: internal combustion engine 1, electric generator 2, transmission 3, ECU (Electronic Control Unit) 4, EHC 5, battery 6, EHC current cut-off device 7, electric generator control circuit 8, voltage and current sensor 9, catalyst downstream temperature sensor 10, rotation sensor 11, and intake air temperature sensor 12.

[0034] An internal combustion engine 1 is equipped with a rotation sensor 11. The rotation sensor 11 detects the rotation and phase of the crankshaft located in the internal combustion engine 1. Additionally, an intake airflow path 13 and an exhaust airflow path 14 are connected to the internal combustion engine 1. An intake airflow path 13 is equipped with an intake pressure sensor 15 and an intake air temperature sensor 12. The intake pressure sensor 15 detects the amount of air flowing into the intake airflow path 13 (inflow rate). The intake air temperature sensor 12 detects the temperature of the air flowing into the intake airflow path 13.

[0035] An EHC5 and a catalyst downstream temperature sensor 10 are installed in the exhaust flow path 14. The EHC5 contains electrodes. The EHC5 heats up by allowing current to flow between the electrodes, thus purifying harmful substances in the exhaust gas. The catalyst downstream temperature sensor 10 is located downstream of the EHC5.

[0036] The downstream temperature sensor 10 detects the temperature of the air after passing through EHC5.

[0037] An electric generator 2 is positioned between the internal combustion engine 1 and the transmission 3. The electric generator 2 is controlled by an electric generator control circuit 8. The electric generator 2 drives the internal combustion engine 1. Additionally, the electric generator 2 operates to generate electricity after the internal combustion engine 1 is started. The electricity generated by the electric generator 2 (generated electricity) is fed into the high-voltage battery 6. The electric generator 2 generates driving force by supplying power from the battery 6. The transmission 3 converts the driving force of the internal combustion engine 1, the driving force of the electric generator 2, or both the driving forces of the internal combustion engine 1 and the electric generator 2 into appropriate torque and speed.

[0038] ECU4 represents a specific example of the electronic control device of the present invention. ECU4 is an arithmetic circuit that performs various data processing. Based on the detection information from the rotation sensor 11, voltage and current sensor 9, catalyst downstream temperature sensor 10, and intake air temperature sensor 12, ECU4 controls the EHC current cutoff device 7. The EHC current cutoff device 7 switches the ON / OFF state of the power supplied to EHC5. Voltage and current sensor 9 detects the voltage and current of the power supplied to EHC5.

[0039] ECU4 outputs a motoring request to the electric generator control circuit 8. Upon receiving the motoring request, the electric generator control circuit 8 controls the electric generator 2, which drives the internal combustion engine to rotate. Additionally, various sensors and actuators (not shown) are connected to ECU4. Based on the detection information from these sensors, ECU4 controls the drive of these actuators (not shown) to control the output of the internal combustion engine 1.

[0040] [Example of the structure of an ECU's functional modules]

[0041] Next, the functional structure of ECU4 will be explained.

[0042] Figure 2 This is a diagram illustrating the structure of the functional modules of ECU4.

[0043] ECU4 includes an estimation unit 41 and a control unit 42.

[0044] The estimation unit 41 acquires detection information from various sensors installed in the engine system (e.g., voltage and current sensor 9, catalyst downstream temperature sensor 10, intake air temperature sensor 12, etc.) and estimates the temperature of EHC5 (hereinafter referred to as "EHC temperature").

[0045] The control unit 42 controls the energization of the EHC 5 based on the EHC temperature estimated by the estimation unit 41. Additionally, the control unit 42 outputs a command to drive the internal combustion engine 1. A drive request is output to the electric generator control circuit 8. Therefore, the control unit 42 outputs control signals to the EHC current cutoff device 7 and the electric generator control circuit 8.

[0046] [ECU Hardware Structure]

[0047] Next, the hardware structure of ECU4 will be explained.

[0048] Figure 3 This is a block diagram representing an example of the hardware structure of ECU4.

[0049] ECU4 includes an A / D converter 52, a CPU (Central Processing Unit) 53 as a central processing unit, a ROM (Read-Only Memory) 54, a RAM (Random Access Memory) 55, a timer circuit 56, and a drive circuit 57. The CPU 53 performs the aforementioned functions by loading a program stored in the ROM 54 (an example of a storage unit) into the RAM 55 and executing it. ECU4 may be configured as, for example, a microcomputer.

[0050] When the signal output from the sensor is an analog signal 50, the A / D converter 52 converts it into a digital signal and outputs it to the CPU 53. The CPU 53 receives the digital signal output from the A / D converter 52 and executes the control logic (program) stored in a storage medium such as ROM 54, thereby performing various calculations, diagnostics, and controls. In addition, the calculation results of the CPU 53 and the conversion results of the A / D converter 52 are temporarily stored in RAM 55.

[0051] In this embodiment, a non-volatile memory such as an EEPROM (Electrically Erasable and Programmable Read-Only Memory) is used as the ROM 54.

[0052] The estimated temperature of EHC5 is stored in ROM54 before the internal combustion engine 1 stops.

[0053] The calculation result of CPU 53 is output as control signal 58 from drive circuit 57. Therefore, the calculation result of CPU 53 is used to control controlled objects such as EHC current cut-off device 7 and electric generator control circuit 8. In addition, CPU 53 uses timer circuit 56 to measure the elapsed time (ECU pause time) from when ECU 4 is stopped until power is turned on.

[0054] When the input signal is a digital signal 51, it is sent directly to the CPU 53. The CPU 53 performs necessary calculations, diagnostics, and control. For example, signals from the rotation sensor 11, the intake cam angle sensor (not shown), and the exhaust cam angle sensor are sent to the CPU 53 as High / Low signals.

[0055] [Relationship between temperature and catalyst resistance in EHC]

[0056] Next, the relationship between catalyst temperature T and catalyst resistance R will be explained.

[0057] Figure 4 It is a graph showing the correlation between catalyst temperature T and catalyst resistance R (temperature-resistance characteristic).

[0058] like Figure 4 As shown, there is a correlation between the temperature of EHC5 (catalyst temperature T) and the resistance value of EHC5 (catalyst resistance value R). The slope of the curve representing the correlation between catalyst temperature T and catalyst resistance value R varies with temperature. In regions with a steep slope, even if there are measurement errors or fluctuations in the catalyst resistance value R, the calculated error of the catalyst temperature T is small. Therefore, in regions with a steep slope, the catalyst temperature T calculated based on the catalyst resistance value R can be used for the energization control of EHC5.

[0059] On the other hand, in regions with a shallow slope, the calculated catalyst temperature T will have a larger error due to measurement errors or fluctuations in the catalyst resistance value R. Therefore, if the catalyst temperature T calculated based on the catalyst resistance value R is used for EHC5 energization control in regions with a shallow slope, insufficient or excessive heating of EHC5 may occur.

[0060] [Handling when power is on]

[0061] Next, we will explain the power-on processing of ECU4.

[0062] Figure 5 This is a flowchart illustrating an example of the processing performed when the power to ECU4 is turned on.

[0063] First, when ECU4 is powered on, ECU4 reads its rest time (S301). In this process, ECU4 uses timer circuit 56 to measure the elapsed time from when ECU4 is at rest until when the power is turned on (hereinafter referred to as "ECU rest time") and obtains its timing result.

[0064] Next, ECU4 reads the last estimated EHC5 temperature (hereinafter referred to as the "last estimated value") from the last operation of ECU4 (S302). The last estimated value is stored, for example, in non-volatile memory. Non-volatile memory can be, for example, an HDD (Hard Disk Drive), SSD (Solid State Drive), floppy disk, optical disk, optical disc, CD-ROM, CD-R, magnetic tape, or other non-volatile memory. Then, ECU4 estimates the EHC temperature Te based on the ECU idle time and the last estimated value (S303).

[0065] The estimation of the EHC temperature Te in S303 corresponds to the second estimation process of the present invention.

[0066] Furthermore, the EHC temperature Te estimated in S303 corresponds to the initial estimated temperature of the present invention. The EHC temperature Te in S303 is estimated based on the relationship between the previous final estimated value, the ECU rest time, and the EHC temperature. Figure 6 This is a graph illustrating the estimation of EHC temperature based on the previous final estimate and ECU downtime. (Example) Figure 6 As shown, the higher the previous final estimate, the higher the estimated EHC temperature Te. Additionally, the shorter the ECU rest time, the higher the estimated EHC temperature Te.

[0067] Next, ECU4 determines whether it is permissible to apply power for temperature measurement based on the EHC temperature Te estimated in S303 (S304). In this process, if the estimated EHC temperature Te is within a predetermined temperature range, ECU4 determines that it is permissible to apply power for temperature measurement ("Yes"). Conversely, if the estimated EHC temperature is outside the predetermined temperature range, ECU4 determines that it is not permissible to apply power for temperature measurement ("No").

[0068] The specified temperature range is based on the used Figure 4 The decision is made based on the region with the steepest slope. Specifically, in the S304 process, if the error in calculating the catalyst temperature T based on the catalyst resistance value R decreases, it is decided to energize EHC5 and calculate the catalyst temperature T based on the catalyst resistance value R. Conversely, if the error in calculating the catalyst temperature T based on the catalyst resistance value R increases, it is decided not to perform the calculation of the catalyst temperature T based on the catalyst resistance value R (and to perform other estimations).

[0069] In S304, if it is determined that power can be supplied for temperature measurement (S304 determines "yes"), ECU4 starts supplying power to EHC5 (S305). When this process ends, ECU4 stops the power supply process. On the other hand, if it is determined in S304 that power cannot be supplied for temperature measurement (S304 determines "no"), ECU4 requests the electric generator control circuit 8 to drive the generator for temperature measurement (S306). After processing in S306, ECU4 stops the power supply process.

[0070] Furthermore, if the previous final estimate or ECU downtime is uncertain due to an abnormality in the non-volatile memory, the EHC temperature Te is estimated to be outside the specified temperature range. Therefore, S304 makes a "no" judgment, prohibiting the power supply for temperature measurement and instead performing a drag-based temperature estimation. As a result, overheating of EHC5 can be prevented, and EHC5 melting can be suppressed.

[0071] [Periodic Processing]

[0072] Next, the cycle processing of ECU4 will be explained.

[0073] Figure 7 This is a flowchart illustrating an example of the periodic processing performed by ECU4.

[0074] The ECU4 performs cycle processing, for example, every 0.1 seconds. First, the ECU4 acquires detection information from various sensors (S501). This detection information includes the rotational speed Ne detected by the rotation sensor 11, the intake manifold pressure Pm detected by the intake pressure sensor 15, and the intake temperature Ta detected by the intake temperature sensor 12. Furthermore, this detection information also includes the EHC downstream temperature Td detected by the catalyst downstream temperature sensor 10, and the voltage Vb and current Ie detected by the voltage and current sensor 9.

[0075] Next, ECU4 performs EHC temperature estimation processing (S502). In S502, ECU4 estimates the temperature of EHC5 based on its resistance value or the downstream temperature Td of EHC5. The EHC temperature estimation processing will be discussed later. Figure 8 Detailed explanation.

[0076] Next, ECU4 performs EHC energization control processing (S503). In S503, ECU4 controls the energization of EHC5 (on / off switching) based on the estimated temperature of EHC5 (EHC estimated temperature) calculated in S502 and the target temperature of EHC5. The EHC energization control processing will be described later. Figure 10Detailed explanation.

[0077] [EHC Temperature Estimation Processing]

[0078] Next, the process of estimating EHC temperature will be explained.

[0079] Figure 8 This is a flowchart illustrating an example of EHC temperature estimation processing performed by ECU4.

[0080] First, ECU4 calculates the resistance value of EHC5 (EHC resistance value Re) based on the voltage Vb and current Ie (S601). Next, ECU4 determines whether the temperature of EHC5 can be estimated based on the calculated EHC resistance value Re (S602).

[0081] In S602, if the EHC resistance value Re is within a specified range of the correlation between the EHC resistance value Re and the EHC temperature, and the calculated EHC resistance value Re shows small and relatively stable fluctuations, ECU4 determines that it can estimate the temperature of EHC5 based on the EHC resistance value Re ("Yes"). If at least one of the above two conditions is not met, ECU4 determines that it cannot estimate the temperature of EHC5 based on the EHC resistance value Re ("No").

[0082] When S602 determines that the temperature of EHC5 can be estimated based on the EHC resistance value Re (when S602 makes a "yes" judgment), ECU4 estimates the EHC temperature Te based on the EHC resistance value Re (S603). The estimation of the EHC temperature Te in S603 corresponds to the third estimation process of the present invention. This estimation of the EHC temperature Te is performed by retrieving a table of temperature-resistance characteristics that is pre-stored in ROM54. After the processing in S603, ECU4 performs the processing in S611, which will be described later.

[0083] If S602 determines that the temperature of EHC5 cannot be estimated based on the EHC resistance value Re (S602 makes a "No" judgment), ECU4 determines whether it is in a state of drive (electric rotation) (S604). If S604 determines that it is not in a state of drive (S604 makes a "No" judgment), ECU4 performs the processing described later in S608.

[0084] When S604 determines that the system is in a dragging state (S604 determines "yes"), ECU4 determines whether the speed Ne is above a specified value and the change in speed Ne is small (S605). When S605 determines that the speed Ne is not above a specified value and the change in speed Ne is small (S605 determines "no"), ECU4 performs the processing described later in S608.

[0085] When S605 determines that the engine speed Ne is above a specified value and the variation of engine speed Ne is small (when S605 makes a "yes" judgment), ECU4 estimates the EHC temperature Te based on the downstream EHC temperature Td (S606). The estimation of the EHC temperature Te in S606 corresponds to the first estimation process of the present invention. The estimation of the EHC temperature Te is calculated based on the relationship between the downstream EHC temperature Td, the intake air temperature Ta, and the EHC temperature Te stored in advance in ROM54.

[0086] Figure 7 This is a graph illustrating the relationship between the downstream EHC temperature Td, the intake air temperature Ta, and the EHC temperature Te. (Example) Figure 7 As shown, the lower the intake air temperature Ta, the higher the estimated EHC temperature Te. Additionally, the higher the downstream EHC temperature Td, the higher the estimated EHC temperature Te. After processing in S606, ECU4 releases the temperature measurement drag request (S607).

[0087] On the other hand, if S604 and S605 determine "No", ECU4 estimates the EHC temperature Te based on the temperature change of EHC5 (S608). The estimation of EHC temperature Te in S608 corresponds to the fourth estimation process of the present invention. In this estimation of EHC temperature Te, the temperature change of EHC5 is first estimated. Specifically, the temperature change of EHC comes from heat exchange with exhaust gas, heat dissipation to external gas, heat of reaction of catalyst, and heating generated by electricity. Then, the EHC temperature Te is estimated by adding these temperature changes of EHC to the previously estimated EHC temperature Te (the previously estimated EHC temperature Te).

[0088] Furthermore, during the period when the internal combustion engine 1 is stopped, the temperature change of EHC5 comes only from heat dissipation to the external gas and heating generated by electrical current. Additionally, the downstream EHC temperature Td can be estimated simultaneously and compared with the measured value to correct for the EHC temperature Te. The estimation of the downstream EHC temperature Td is based on the temperature of the exhaust gas before entering EHC5 and the previously estimated EHC temperature Te.

[0089] Next, ECU4 determines whether the stopping time of internal combustion engine 1 has reached the specified value (S609). If S609 determines that the stopping time of internal combustion engine 1 has not reached the specified value (the case where S609 makes a "no" judgment), ECU4 performs the processing described later in S611.

[0090] When S609 determines that the duration of the internal combustion engine 1's shutdown has reached a predetermined value (when S609 makes a "yes" judgment), ECU4 requests a temperature measurement drag from the electric generator control circuit 8 (S610). During the period when the internal combustion engine 1 is stopped, the detection information from the downstream catalyst temperature sensor 10 cannot be reflected in the estimated temperature of EHC5, and errors will accumulate. Therefore, a temperature measurement drag is performed to prevent error accumulation.

[0091] After processing in steps S603, S607, and S610, or if a "No" judgment is made in S609, ECU4 stores the estimated EHC temperature Te in non-volatile memory (S611). The EHC temperature Te stored in non-volatile memory is used as the previous final estimate during the ECU4's power-on processing. After processing in S611, ECU4 ends the EHC temperature estimation process.

[0092] [EHC Power-On Control Processing]

[0093] Next, the EHC power-on control process will be explained.

[0094] Figure 10 This is a flowchart illustrating an example of EHC power-on control processing performed by ECU4.

[0095] First, ECU4 sets the target temperature for EHC5 (S801). The target temperature for EHC5 only needs to be set to a temperature that activates the catalyst. In addition, if the temperature of the internal combustion engine 1 and the exhaust gas are expected to be low, it is best to set the target temperature higher than the temperature that activates the catalyst.

[0096] Next, ECU4 determines whether it is in the period of requesting temperature measurement drag (S802). If S802 determines that it is in the period of requesting temperature measurement drag (if S802 makes a "yes" judgment), ECU4 performs the processing described later in S805.

[0097] On the other hand, when S802 determines that it is not in the period of requesting temperature measurement for dragging (when S802 makes a "no" judgment), ECU4 determines that the EHC temperature estimation process is in progress (refer to...). Figure 8 The ECU4 checks whether the estimated EHC temperature Te is lower than the target temperature (S803). If S803 determines that the estimated EHC temperature Te is higher than the target temperature (S803 makes a "no" judgment), the ECU4 performs the processing described later in S805.

[0098] On the other hand, when S803 determines that the estimated EHC temperature Te is lower than the target temperature (when S803 makes a "yes" judgment), ECU4 controls the EHC current cutoff device 7 to energize EHC5 (S804). After processing in S804, ECU4 ends the EHC energization control process.

[0099] If S802 determines "yes" or S803 determines "no", ECU4 controls EHC current cutoff device 7 to stop the energization of EHC5 (S805). After processing in S805, ECU4 ends the EHC energization control process. Thus, during the period when a drag is requested for temperature measurement (S802 determines "yes"), the estimated EHC temperature Te may contain errors; therefore, to prevent melting, the energization of EHC5 is stopped.

[0100] Furthermore, the target temperature for EHC5 can also be used to induce hysteresis, thus preventing repeated energizing and de-energizing within a short period. Additionally, the voltage applied to the EHC can be adjusted based on the difference between the estimated EHC temperature and the target temperature. Furthermore, duty control can be employed for EHC energizing control, and the duty value can be varied.

[0101] [EHC Temperature Control]

[0102] Next, the temperature control operation of EHC5 will be explained.

[0103] Figure 11 This is one of the diagrams illustrating the temperature control operation of EHC5.

[0104] When ECU4 is powered on, the temperature of EHC5 is estimated based on the ECU's rest time and the previous final estimate. Then, based on the estimated EHC5 temperature, it is determined whether a temperature estimation based on the powered-on EHC5 can be performed. If it is determined that a temperature estimation based on the powered-on EHC5 cannot be performed, then... Figure 11 As shown, start temperature measurement by dragging (time a).

[0105] By using a temperature measuring device, at the point when the speed of the internal combustion engine 1 stabilizes, the temperature of EHC5 is estimated (time b) based on the detection information from the downstream temperature sensor 10 of the catalyst. At time b, there is a difference between the estimated temperature of EHC5 and the estimated temperature at time b. This is because the estimated temperature of EHC5 at time b is more accurate than that at time a.

[0106] At time b, if the estimated temperature of EHC5 has not yet reached the target EHC temperature, power is applied to EHC5. The target EHC temperature is set as a predetermined range from the upper limit to the lower limit of the target EHC temperature. After time b, the EHC temperature is estimated by accumulating the temperature changes of EHC5. When the estimated temperature of EHC5 reaches the upper limit of the target EHC temperature, power application to EHC5 is stopped (time c). Thus, the estimated temperature of EHC5 gradually decreases.

[0107] Next, when the estimated temperature of EHC5 reaches the lower limit of the target EHC temperature, EHC5 is energized (time d). Then, when the estimated temperature of EHC5 reaches the upper limit of the target EHC temperature, energizing EHC5 is stopped (time e). In this way, feedback control is performed based on the estimated temperature of EHC5 and the target EHC temperature (upper and lower limits). In addition, after the internal combustion engine 1 is started due to the driver's request or insufficient battery power (time f), the temperature of EHC5 is estimated and the decision to energize EHC5 is made one by one.

[0108] Figure 12 This is a diagram illustrating the temperature control operation of EHC5 (Part Two).

[0109] When ECU4 is powered on, the temperature of EHC5 is estimated based on the ECU's rest time and the previous final estimate. Then, based on the estimated EHC5 temperature, it is determined whether a power-on-based EHC5 temperature estimation can be performed. If it is determined that a power-on-based EHC5 temperature estimation can be performed, then... Figure 12 As shown, EHC5 is energized at time a2.

[0110] Then, the catalyst resistance R is calculated based on the voltage and current obtained from the voltage and current sensor 9, and the temperature of EHC5 is estimated based on the catalyst resistance R (time b2). At time b2, if the estimated temperature of EHC5 has not reached the target EHC temperature, the energization of EHC5 is maintained. When the estimated temperature of EHC5 reaches the upper limit of the target EHC temperature, the energization of EHC5 is stopped (time c).

[0111] After time c and use Figure 11 The actions described are the same.

[0112] Figure 13 This is a diagram illustrating the temperature control operation of EHC5 (Part 3).

[0113] When ECU4 is powered on, the temperature of EHC5 is estimated based on the ECU's rest time and the previous final estimate. Then, based on the estimated EHC5 temperature, it is determined whether a temperature estimation based on the powered-on EHC5 can be performed. If it is determined that a temperature estimation based on the powered-on EHC5 cannot be performed, then... Figure 13 As shown, start temperature measurement by dragging (time a).

[0114] By using a temperature-measuring actuator, at the point when the internal combustion engine 1's speed stabilizes, the temperature of EHC5 is estimated (time b) based on the detection information from the downstream temperature sensor 10. After time b, feedback control is executed based on the estimated temperature of EHC5 and the target EHC temperature (upper and lower limits). Thus, by repeatedly energizing and de-energizing EHC5, the estimated temperature of EHC5 remains within the specified range.

[0115] However, when the internal combustion engine 1 is stopped, air does not flow in the exhaust flow path 14. Therefore, the downstream temperature sensor 10 cannot detect the temperature of the air after passing through EHC5. Consequently, the detection information from the downstream temperature sensor 10 cannot be reflected in the temperature estimation of EHC5. Therefore, when the internal combustion engine 1 is stopped, the estimated temperature of EHC5 is calculated by accumulating the heating generated by the energization of EHC5 and the heat dissipation to the external gas.

[0116] When calculating the estimated temperature of EHC5 by accumulating the heating generated by the energization of EHC5 and the heat dissipation to the external gas, as shown by the solid and dashed lines in the figure, an error gradually accumulates between the estimated temperature of EHC5 (solid line) and the actual temperature of EHC5 (dashed line). Therefore, at a time point (time j) after a predetermined time has elapsed after the internal combustion engine 1 stops (time i), temperature measurement is initiated. Then, the temperature of EHC5 is estimated (time k) based on the detection information from the downstream temperature sensor 10 of the catalyst. This ensures that the estimated temperature of EHC5 is consistent with or close to the actual temperature.

[0117] 2. Summary

[0118] As explained above, the electronic control unit (ECU4) of the above embodiment is used to control an engine system, which includes: an internal combustion engine (internal combustion engine 1); an electric motor (electric generator 2) capable of driving the internal combustion engine; a catalyst (EHC5) for purifying exhaust gases, which is disposed in the exhaust passage (exhaust flow path 14) of the internal combustion engine and has the function of being heated by power supply; and a downstream temperature sensor (catalyst downstream temperature sensor 10) disposed downstream of the catalyst. The electronic control unit includes: a control unit (control unit 42) capable of driving the internal combustion engine using the electric motor; and an estimation unit (estimation unit 41) capable of performing a first estimation process, in which the temperature of the catalyst is estimated based on the detection information of the downstream temperature sensor when driving the internal combustion engine. Thus, air after passing through the catalyst can be supplied to the downstream temperature sensor, so the temperature of the catalyst can be estimated with high accuracy based on the detection information of the downstream temperature sensor. In addition, the rotation of the internal combustion engine is a driven rotation without fuel supply (electric rotation), so even when the temperature of the catalyst is low and the purification capacity is low, it is impossible to release unburned gas into the atmosphere.

[0119] Furthermore, the estimation unit (estimation unit 41) of the electronic control device (ECU4) in the above embodiment performs a second estimation process before the internal combustion engine (internal combustion engine 1) is started and before the first estimation process is performed. In the second estimation process, the temperature of the catalyst is estimated based on the estimated temperature of the catalyst (EHC5) at the time of the last power cut-off and the elapsed time since the last power cut-off. Therefore, the temperature of the catalyst can be estimated before the internal combustion engine is started and before the first estimation process is performed (when the power is turned on). In addition, the temperature of the catalyst can be estimated without energizing the catalyst.

[0120] Furthermore, in the above-described embodiment, when the initial estimated temperature estimated by the second estimation process is outside the predetermined temperature range, the estimation unit (estimation unit 41) of the electronic control device (ECU4) estimates the temperature of the catalyst (EHC5) through the first estimation process. Therefore, even if the calculated catalyst temperature error increases due to measurement errors or fluctuations in the catalyst's resistance value, the catalyst temperature can be estimated with high accuracy based on the detection information from the downstream temperature sensor, even without estimating the catalyst temperature based on its resistance value.

[0121] Furthermore, in the case where the estimated temperature of the catalyst (EHC5) at the time of the last power cut-off or the elapsed time since the last power cut-off is uncertain, the estimation unit (estimation unit 41) of the electronic control device (ECU4) in the above embodiment estimates the initial estimated temperature in a manner outside the prescribed temperature range. Therefore, the catalyst temperature is not estimated based on the catalyst's resistance value, and thus the power supply to the catalyst can be stopped. As a result, overheating of the catalyst can be prevented, and catalyst melting loss can be suppressed.

[0122] Furthermore, the estimation unit (estimation unit 41) of the electronic control device (ECU4) in the above embodiment performs a third estimation process when the initial estimated temperature estimated by the second estimation process is within a predetermined temperature range. In the third estimation process, the temperature of the catalyst is estimated based on the resistance value of the catalyst (EHC5). Therefore, even if there is a measurement error or fluctuation in the resistance value of the catalyst, the error in the calculated temperature of the catalyst is small, and the temperature of the catalyst can be estimated based on the resistance value of the catalyst.

[0123] Furthermore, the estimation unit (estimation unit 41) of the electronic control device (ECU4) in the above embodiment performs a fourth estimation process after performing the first estimation process or the third estimation process. In the fourth estimation process, the temperature of the catalyst is estimated by accumulating the estimated value of the temperature change of the catalyst (EHC5). Thus, the temperature of the catalyst can be estimated even after performing the first estimation process or the third estimation process.

[0124] As a result, feedback control can be performed based on the catalyst temperature estimated through the fourth estimation process, and the catalyst temperature can be controlled within a specified range.

[0125] Furthermore, in the electronic control unit (ECU4) of the above embodiment, after the fourth estimation process is performed, the control unit (control unit 42) drives the internal combustion engine (internal combustion engine 1) after it has been continuously stopped for a predetermined time. The estimation unit (estimation unit 41) performs the first estimation process while driving the internal combustion engine. As a result, the estimated temperature of the catalyst (EHC5) can be made to be consistent with or close to the actual temperature of the catalyst.

[0126] The embodiments of the electronic control device of the present invention, including their effects, have been described above. However, the electronic control device of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the claimed technical solution. Furthermore, the above detailed description of the embodiments is provided for ease of understanding and explanation of the present invention, and is not limited to having all the described structures.

[0127] For example, the above embodiment employs a structure in which an electric generator 2 is installed between the internal combustion engine 1 and the gearbox 3. However, for the engine system that is the object of control of the electronic control device of the present invention, it is sufficient to have an electric motor capable of driving the internal combustion engine.

[0128] Explanation of reference numerals in the attached figures

[0129] 1…Internal combustion engine, 2…Electric generator, 3…Transmission, 4…ECU (Electronic Control Unit), 5…EHC, 6…Battery, 7…EHC current cutoff device, 8…Electric generator control circuit, 9…Voltage and current sensor, 10…Catalyst downstream temperature sensor, 11…Rotation sensor, 12…Intake air temperature sensor, 13…Intake airflow path, 14…Exhaust airflow path, 15…Intake air pressure sensor, 41…Estimation unit, 42…Control unit, 50…Analog signal, 51…Digital signal, 52…A / D converter, 53…CPU, 54…ROM, 55…RAM, 56…Timer circuit, 57…Drive circuit, 58…Control signal

Claims

1. An electronic control device for controlling an engine system, The engine system includes: An internal combustion engine; an electric motor capable of driving the internal combustion engine; The catalyst for purifying exhaust gas is disposed in the exhaust passage of the internal combustion engine and has the function of being heated by electricity. and a downstream temperature sensor located downstream of the catalyst, The electronic control device includes: The control unit, which uses the electric motor to drive the internal combustion engine without supplying fuel; and The estimation unit is capable of performing a first estimation process, in which the temperature of the catalyst is estimated based on detection information from the downstream temperature sensor when the internal combustion engine is driven without fuel supply. The estimation unit performs a second estimation process before the internal combustion engine is started and before the first estimation process is implemented. In the second estimation process, the initial estimated temperature of the catalyst is estimated based on the estimated temperature of the catalyst at the time of the last power cut-off and the elapsed time since the last power cut-off. When the initial estimated temperature obtained through the second estimation process is outside a predetermined temperature range, the estimation unit estimates the temperature of the catalyst through the first estimation process. When the initial estimated temperature is within a specified temperature range, a third estimation process is performed, in which the temperature of the catalyst is estimated based on the catalyst's resistance value. Within the specified temperature range, the slope of the temperature change characteristic of the catalyst's resistance value is greater than the slope of the temperature change characteristic outside the specified temperature range.

2. The electronic control device according to claim 1, wherein, If the estimated temperature of the catalyst at the time of the last power cut-off or the elapsed time since the last power cut-off is uncertain, the estimation unit estimates the initial estimated temperature as being outside the specified temperature range.

3. The electronic control device according to claim 1, wherein, After performing the first estimation process or the third estimation process, the estimation unit performs a fourth estimation process, in which the temperature of the catalyst is estimated by accumulating the estimated values ​​of the temperature change of the catalyst.

4. The electronic control device according to claim 3, wherein, After the fourth estimation process is performed, the control unit starts the internal combustion engine to move, provided that the internal combustion engine has been continuously stopped for a predetermined time. The estimation unit performs the first estimation process when the internal combustion engine is being towed.

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