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JP-2026075194-A - Control method and control device for an internal combustion engine

JP2026075194AJP 2026075194 AJP2026075194 AJP 2026075194AJP-2026075194-A

Abstract

[Problem] When the internal combustion engine is started with a delay after the start of preheating by EHC, the reduction in the accuracy of catalyst temperature estimation caused by the heat that EHC imparts to the three-way catalyst during the preheating period is suppressed. [Solution] Preheating of the EHC in the exhaust passage begins when the vehicle's main switch is turned on (time t0). The temperature of the three-way catalyst (solid line T1), which is located adjacent to the EHC, is estimated by accumulating the temperature rise per minute unit time due to the EHC temperature during the preheating period. The estimated temperature at the time of engine startup (time t1) is used as the initial temperature, and the catalyst temperature after engine startup is estimated by accumulating the temperature change per minute unit time based on the exhaust gas temperature. The accuracy of temperature estimation is higher compared to the comparative example (dashed line T2) which does not consider the heat that the EHC imparts to the three-way catalyst. [Selection Diagram] Figure 3

Inventors

  • 横山 仁
  • 井上 晶
  • 糸山 浩之
  • 西 大紀

Assignees

  • 日産自動車株式会社

Dates

Publication Date
20260508
Application Date
20241022

Claims (9)

  1. A control method for an internal combustion engine in which an electrically heated catalyst equipped with a carrier that generates heat when an electric current is applied is provided adjacent to a three-way catalyst, The temperature of the three-way catalytic converter after starting the internal combustion engine is estimated by accumulating the temperature change over minute units of time based on the exhaust gas temperature from the initial temperature at startup. The initial temperature described above is determined by including the heat that the electric heating catalyst imparts to the three-way catalyst during the preheating period of the electric heating catalyst. A method for controlling an internal combustion engine.
  2. During the preheating period of the above-mentioned electrically heated catalyst, the temperature of the three-way catalyst is estimated by accumulating the temperature rise per minute unit time due to the heat that the electrically heated catalyst imparts to the three-way catalyst. The estimated temperature when the internal combustion engine starts is defined as the initial temperature mentioned above. A method for controlling an internal combustion engine according to claim 1.
  3. Determine the temperature of the electric heating catalyst during the preheating period. Based on the temperature of this electrically heated catalyst, the temperature rise per minute unit time is determined. The method for controlling an internal combustion engine according to claim 2.
  4. Before starting the internal combustion engine, the electric heating catalyst is preheated, causing the estimated temperature of the three-way catalyst to reach its partially activated temperature. From this point until the internal combustion engine is started, the target temperature of the electric heating catalyst is gradually lowered from the basic target temperature. A method for controlling an internal combustion engine according to claim 1.
  5. Based on the energizing time of the electric heating catalyst, the integral value of the temperature of the electric heating catalyst and the energizing time, or the estimated temperature of the three-way catalyst, the amount of reduction that should be made from the basic target temperature is calculated. This decrease in temperature is used to determine the target temperature of the electroheated catalyst. The method for controlling an internal combustion engine according to claim 4.
  6. The above-mentioned internal combustion engine is an internal combustion engine that drives the generator in a series hybrid vehicle. When the main switch of the above-mentioned series hybrid vehicle is turned on, preheating of the above-mentioned electrically heated catalyst is initiated. The above internal combustion engine is started in response to power generation demands. A method for controlling an internal combustion engine according to claim 1.
  7. The above-mentioned electrically heated catalyst has a three-way catalyst positioned at both the inlet and outlet sides. We will estimate the temperature of at least one of these two three-way catalysts. A method for controlling an internal combustion engine according to claim 1.
  8. Regarding the exhaust flow, the upstream three-way catalytic converter and the downstream electrically heated catalytic converter are arranged vertically. The above-mentioned electrically heated catalyst is positioned below the above-mentioned three-way catalyst. A method for controlling an internal combustion engine according to claim 1.
  9. A control device for an internal combustion engine in which an electrically heated catalyst equipped with a carrier that generates heat when an electric current is applied is provided adjacent to a three-way catalyst, The temperature of the three-way catalytic converter after starting the internal combustion engine is estimated by accumulating the temperature change over minute units of time based on the exhaust gas temperature from the initial temperature at startup. The initial temperature described above is determined by including the heat that the electric heating catalyst imparts to the three-way catalyst during the preheating period of the electric heating catalyst. Control device for internal combustion engines.

Description

This invention relates to a control technology for an internal combustion engine, which involves equipping the exhaust passage with an electrically heated catalyst and preheating the electrically heated catalyst by energizing it before starting the internal combustion engine in order to accelerate the activation of a three-way catalyst adjacent to the electrically heated catalyst. To suppress emission degradation at low temperatures of a three-way catalyst, electrically heated catalysts (so-called EHCs) are known, configured to raise the temperature of the catalyst support when electricity is applied. Such EHCs are generally small in volume and, as disclosed in Patent Document 1, are often used in combination with a general three-way catalyst. Patent Document 1 discloses a configuration in which an EHC and two three-way catalysts, positioned adjacent to each other before and after the EHC, are housed within a single casing that serves as a catalyst converter. Japanese Patent Application Publication No. 5-59938 Diagram illustrating the configuration of a series hybrid vehicle.Diagram illustrating the configuration of the intake and exhaust systems of an internal combustion engine.A time chart showing the change in the estimated catalyst temperature of one embodiment compared with conventional characteristics.A time chart showing the correction of the EHC target temperature after preheating is complete.A characteristic diagram showing the characteristics of the decrease in the EHC target temperature. The following describes in detail an embodiment of this invention based on the drawings. Figure 1 schematically shows the configuration of a series hybrid vehicle in one embodiment to which this invention is applied. The series hybrid vehicle comprises a power generation motor generator 1 that mainly operates as a generator, an internal combustion engine 2 used as a power generation internal combustion engine that drives the power generation motor generator 1 according to power demands, a traction motor generator 4 that mainly operates as a motor to drive the drive wheels 3, and a battery 5 that stores the generated electricity. The electricity obtained by the internal combustion engine 2 driving the power generation motor generator 1 is stored in the battery 5 via an inverter device (not shown). The traction motor generator 4 is driven and controlled using the power from the battery 5. The electricity generated during regeneration by the traction motor generator 4 is also stored in the battery 5 via an inverter device (not shown). The operation of the motor generators 1 and 4, the charging and discharging of the battery 5, and the operation of the internal combustion engine 2 are controlled by the controller 6. The controller 6 is composed of multiple controllers connected to each other so as to be able to communicate with one another, including a motor controller 7 that controls the motor generators 1 and 4, an engine controller 8 that controls the internal combustion engine 2, and a battery controller 9 that manages the battery 5. Information such as the opening of the accelerator pedal (not shown) and vehicle speed is input to the controller 6. The battery controller 9 also determines the State of Charge (SOC) of the battery 5 based on the voltage and current of the battery 5. When the SOC drops to a predetermined level, the internal combustion engine 2 is started via the engine controller 8 and power is generated. The driving modes of such a series hybrid vehicle include an EV mode in which the vehicle runs on the power of the battery 5 without combustion operation of the internal combustion engine 2, and a HEV mode in which the vehicle runs while generating power through combustion operation of the internal combustion engine 2. Furthermore, even if the SOC is above a certain level, if the required driving force of the vehicle is relatively large, the internal combustion engine 2 is driven and the vehicle runs in HEV mode. Therefore, while the vehicle's main switch is on, the internal combustion engine 2 will repeatedly cycle between combustion operation and combustion shutdown. Figure 2 shows the configuration of the intake and exhaust systems of the internal combustion engine 2. The internal combustion engine 2 in one embodiment is a four-stroke cycle spark-ignition internal combustion engine (a so-called gasoline engine) equipped with a turbocharger 13 as a supercharger. For example, it is a so-called direct-injection type internal combustion engine where fuel is injected directly into the cylinder by a fuel injector. A port injection type configuration is also possible. The intake passage 12 of the internal combustion engine 2 contains a compressor 15 of a turbocharger 13. Downstream of the compressor 15 is an electronically controlled throttle valve 21 that controls the intake air volume. Between the compressor 15 and the throttle valve 21 is a water-cooled intercooler 22, for example, to cool the super