JP2014118874A - Exhaust purification control device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably perform power supply to an electric heater for heating an exhaust purification device and power supply to an on-vehicle electric device other than the electric heater by a single accumulator.SOLUTION: This exhaust purification control device of an engine comprises an electric heater 24 for heating the exhaust purification device, control means and activation continuing means. The control means carries electricity to an on-vehicle electric device 52 and the electric heater 24 until a power accumulation amount of the accumulator 51 is lowered to a threshold power accumulation amount when a temperature of the exhaust purification device is lower than a prescribed threshold temperature in a state where power is supplied to only the on-vehicle electric device 52 from the accumulator 51. The activation continuing means continues the activation of the exhaust purification device when the temperature of the exhaust purification device is lower than the threshold temperature after electricity-carrying to the electric heater 24.

Description

  The present invention relates to an engine exhaust purification control device that controls an exhaust purification device provided in an exhaust passage of an engine.

  An engine with excellent fuel efficiency is ecological and is preferably evaluated as being economical, while the exhaust gas temperature is lowered as fuel efficiency is improved. There is a problem that it becomes difficult to activate an exhaust purification device such as a catalyst or an oxidation catalyst.

  In Patent Document 1, a filter that is provided in an exhaust gas passage of a vehicle and captures particulates in the exhaust gas, an electric heater for heating and regenerating the filter, and a first battery that supplies a power source current to various devices of the vehicle And an exhaust gas purifying apparatus including a second battery different from the first battery as a power source of the electric heater. In that case, a lead-acid battery is used as the first battery, and a capacitor capable of discharging a large current in a short time is used as the second battery.

  Patent Document 2 discloses that a filter with a catalyst that is provided in an exhaust pipe and collects particulates in exhaust gas is heated and regenerated by an electric heater and additional injection of fuel in an expansion stroke.

JP 2008-8239 A (paragraphs 0010 and 0024) JP-A-7-279645 (paragraphs 0025, 0043-0046)

  As a measure for actively activating the exhaust purification device on the exhaust passage, it is conceivable to forcibly heat the exhaust purification device using an electric heater as described in Patent Documents 1 and 2. However, since the electric heater consumes a large amount of power, the use of the electric heater significantly reduces the amount of electricity stored in the power storage device that is the power source, and there is a concern that power will be insufficient for other in-vehicle electric devices such as audio and air conditioners. The

  An object of the present invention is to stably supply power to an electric heater for heating an exhaust purification device and power supply to an in-vehicle electric device other than the electric heater with a single power storage device. And

  In order to solve the above-mentioned problems, the present invention relates to an engine exhaust purification control device that controls an exhaust purification device provided in an exhaust passage of an engine, and a heating device for heating the exhaust purification device A vehicle-mounted electrical device other than the heating device, a power storage device for supplying power to the heating device and the vehicle-mounted electrical device, temperature detection means for detecting the temperature of the exhaust purification device, and the power storage device When the temperature detected by the temperature detecting means is lower than a predetermined threshold temperature in a state where electric power is supplied only to the in-vehicle electric device from until the electric storage amount of the electric storage device decreases to the predetermined threshold electric storage amount A control means for energizing the in-vehicle electrical device and the heating device from the power storage device, and after energization to the heating device by the control means, An engine exhaust gas purification control apparatus comprising: an activation continuation means for continuing activation of the exhaust gas purification apparatus when the temperature detected by the temperature detection means is lower than the threshold temperature. (Claim 1).

  According to the present invention, when the temperature of the exhaust gas purification device provided in the exhaust passage of the engine is lower than a predetermined threshold temperature, the heating device for heating the exhaust gas purification device is energized. Even when the apparatus is forcibly heated by the heating device and the exhaust purification apparatus on the exhaust passage is difficult to activate, the exhaust purification apparatus can be actively activated.

  At that time, since the power storage device is energized to the heating device until the power storage amount of the power storage device decreases to a predetermined threshold power storage amount, even if the heating device is used, the power storage amount of the power storage device is significantly reduced. Even so, there is no drop below the threshold power storage amount, and a shortage of electric power to the in-vehicle electric device is avoided. Therefore, the power supply to the heating device and the power supply to the other on-vehicle electric devices are stably covered by a single power storage device.

  Furthermore, after the energization of the heating device, when the temperature of the exhaust purification device has not yet risen to the threshold temperature, the exhaust purification device continues to be activated, so that the function of the exhaust purification device is reliably realized. Or recover.

  In the present invention, it is preferable that the control unit performs the heating until the amount of power stored in the power storage device is reduced to the threshold power storage amount when power is also supplied from the power storage device to the heating device. The time that can be energized to the power device is calculated from the current power storage amount of the power storage device and the current consumption of the in-vehicle electric device, and from the power storage device to the in-vehicle electric device and the heating device until the calculated time elapses. It supplies electricity (Claim 2).

  According to this configuration, it is possible to energize the heating device from the current power storage amount of the power storage device and the current consumption of the in-vehicle electrical device other than the heating device until the power storage amount of the power storage device decreases to the threshold power storage amount. Time is calculated, and the power storage device is energized from the power storage device for the calculated time, so even if the power storage amount of the power storage device significantly decreases due to the use of the heating device, the power storage device decreases below the threshold power storage amount. Insufficient power to the in-vehicle electric device is avoided. Therefore, the power supply to the heating device and the power supply to the other on-vehicle electric devices are stably covered by a single power storage device.

  Further, it is not necessary to determine whether or not the amount of electricity stored in the power storage device has decreased to the threshold amount of electricity during energization of the heating device.

  In the present invention, preferably, the control unit stops energization of the heating device when the temperature detected by the temperature detection unit rises to the threshold temperature during energization of the heating device. (Claim 3).

  According to this configuration, it is possible to avoid wasteful consumption of the amount of power stored when the temperature of the exhaust emission control device reaches the threshold temperature during energization of the heating device.

  In the present invention, it is preferable that the activation continuation unit performs post injection in which fuel is injected between an expansion stroke and an exhaust stroke.

  According to this configuration, the temperature of the exhaust gas flowing into the exhaust gas purification device becomes higher due to post-injection. Therefore, after the energization of the heating device is stopped while the energization of the heating device is stopped to avoid overdischarge of the power storage device However, the activation of the exhaust emission control device can be continued by post injection.

  In the present invention, preferably, the activation continuation means suppresses or stops energization to a predetermined on-vehicle electric device among the on-vehicle electric devices, while continuing to energize the heating device (claim). Item 5).

  According to this configuration, since the rate of decrease in the amount of power stored in the power storage device is reduced by suppressing or stopping the power supply to a predetermined in-vehicle electric device, the power supply to the heating device is avoided while avoiding overdischarge of the power storage device. By continuing the above, the activation of the exhaust emission control device can be continued by the heating device.

  In the present invention, it is preferable that the activation continuation unit charges the power storage device and supplies power to the heating device again (claim 6).

  According to this configuration, it is possible to continue the activation of the exhaust emission control device by the heating device by repeatedly energizing the heating device while avoiding overdischarge of the power storage device by charging the power storage device. .

  In the present invention, it is preferable that the activation continuation unit performs post-injection in which fuel is injected between an expansion stroke and an exhaust stroke during charging of the power storage device.

  According to this configuration, the activation of the exhaust emission control device can be continued by post injection even during charging of the power storage device.

  In this invention, Preferably, the said activation continuation means makes a power generation device generate electric power, and supplies with electricity the said heating device with the generated electric power (Claim 8).

  According to this configuration, by energizing the heating device with the electric power generated by the power generation device, the activation of the exhaust emission control device can be continued by the heating device while avoiding overdischarge of the power storage device.

  In the present invention, it is preferable that the activation continuation unit is configured to energize the in-vehicle electrical device while reducing the generated voltage and bypassing the DC / DC converter (Claim 9).

  According to this configuration, energization of the in-vehicle electrical device is supplied without going through the DC / DC converter, and thus power consumption by the DC / DC converter can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power supply to the electric heater for heating an exhaust gas purification apparatus and the electric power supply to vehicle-mounted electric devices other than the said electric heater can be stably provided with a single electrical storage apparatus. The present invention is particularly suitable for an engine having excellent fuel efficiency.

1 is a schematic configuration diagram of an engine exhaust gas purification control apparatus according to an embodiment of the present invention. It is sectional drawing of the oxidation catalyst for showing arrangement | positioning of the electric heater employ | adopted with the said exhaust gas purification control apparatus. It is a block diagram of the electric system of the engine. It is a control system figure of the engine. 3 is a flowchart of an exhaust purification control operation according to a first control example. It is a time chart. 7 is a flowchart of an exhaust purification control operation according to a second control example. It is a time chart. 12 is a flowchart of an exhaust purification control operation according to a third control example. It is a time chart. 12 is a flowchart of an exhaust purification control operation according to a fourth control example. It is a time chart. 12 is a flowchart of an exhaust purification control operation according to a fifth control example. 14 is a flowchart of an exhaust purification control operation according to a sixth control example. 16 is a flowchart of an exhaust purification control operation according to a seventh control example. 16 is a flowchart of an exhaust purification control operation according to an eighth control example. 16 is a flowchart of an exhaust purification control operation according to a ninth control example.

(1) Overall Configuration FIG. 1 is a schematic configuration diagram of an engine exhaust purification control apparatus according to the present embodiment. The engine according to the present embodiment is a diesel engine that does not require an ignition device that self-ignites the fuel injected into the high-pressure and high-temperature combustion chamber. A plurality of cylinders 2 (only one is shown in the figure) is formed in the engine main body 1, and a piston 3 is inserted into each cylinder 2. The piston 3 is connected to the crankshaft 4 via a connecting rod. A combustion chamber 5 is formed above the piston 3, and a fuel injection valve 6 is provided at the top of the combustion chamber 5.

  The fuel injection valve 6 incorporates a needle valve and a solenoid (not shown). When a pulse signal is input, the fuel injection valve 6 is driven and opened for a time corresponding to the pulse width at the pulse input timing. A corresponding amount of fuel is injected into the combustion chamber 5.

  An intake passage 10 and an exhaust passage 20 are connected to the combustion chamber 5 of each cylinder 2. An intake valve 11 is provided between the intake passage 10 and the combustion chamber 5, and an exhaust valve 21 is provided between the exhaust passage 20 and the combustion chamber 5. A throttle valve 12 is disposed in the intake passage 10. The throttle valve 12 controls the amount of intake air flowing into the cylinder 2 by adjusting the cross-sectional area of the intake passage 10 in accordance with the opening. A DOC (oxidation catalyst) 22 and a DPF (diesel particulate filter) 23 are arranged in this order from the upstream side in the exhaust passage 20.

The DOC 22 is an exhaust purification device for promoting an oxidation reaction of exhaust gas discharged from the cylinder 2. CO (carbon monoxide) and HC (hydrocarbon) in the exhaust gas are oxidized when passing through the DOC 22 and purified to CO ₂ (carbon dioxide) and H ₂ O (water). The DOC 22 also plays a role of increasing the exhaust gas temperature by such an oxidation reaction of the exhaust gas that occurs inside the DOC 22 and causing the high-temperature exhaust gas to flow into the downstream DPF 23.

  The DPF 23 is an exhaust purification device for collecting particulates such as soot contained in the exhaust gas discharged from the cylinder 2. The DPF 23 is a wall-through filter made of ceramics such as SiC (silicon carbide). Fine particles in the exhaust gas are collected on the cell wall when passing through the cell wall of the DPF 23 from the inflow side to the outflow side. The DPF 23 is a filter with a catalyst that supports a catalyst (for example, platinum or the like) that promotes an oxidation reaction of exhaust gas. The DPF 23 has a function (self-regeneration function) of raising the exhaust gas temperature by such an oxidation reaction of the exhaust gas occurring inside the DPF 23 and burning and removing the collected fine particles.

  Since the engine according to the present embodiment has excellent fuel efficiency, the exhaust gas temperature is relatively low, and the DOC 22 and the DPF 23 provided in the exhaust passage 20 tend to be difficult to activate. Therefore, in the present embodiment, the fuel injection valve 6 is configured to be able to execute post injection that injects fuel in the expansion stroke after the main injection, in addition to main injection that injects fuel near the top dead center of the compression stroke. ing. When the post-injection is executed, the fuel is injected in the expansion stroke, so that the injected fuel is reduced in the rate at which the thermal energy of combustion is converted into mechanical energy that pushes the piston 3. Therefore, the exhaust gas temperature of the post-injected fuel becomes higher than the exhaust gas temperature of the main injected fuel. Therefore, DOC22 and DPF23 can be activated actively by performing post injection.

  However, post-injection can cause a reduction in fuel efficiency and dilution of engine oil. In this embodiment, the DOC 22 is forcibly heated using an electric heater as a heating device for heating the exhaust purification device. Thus, the DOC 22 and the DPF 23 are actively activated. Specifically, as shown in FIG. 2, in the exhaust passage 20, an electric heater 24 made of, for example, a nichrome wire is disposed immediately upstream of the catalyst carrier 22 a of the DOC 22. When the electric heater 24 is energized, the electric heater 24 generates heat to heat the exhaust gas, and the heated exhaust gas flows into the catalyst carrier 22a to heat the DOC 22 and the DOC 22 is activated.

  FIG. 2 shows an example in which the electric heater 24 is arranged on the outer peripheral portion immediately upstream of the catalyst carrier 22a. However, the electric heater 24 may be arranged in another part of the catalyst carrier 22a depending on the situation. For example, an electric heater may be wound around the outer peripheral surface of the catalyst carrier 22a or may be passed through the inside of the catalyst carrier 22a. Further, a microwave or the like may be used instead of the electric heater as a heating device of the exhaust gas purification apparatus.

  As described above, the post-injection has a problem that the fuel efficiency is lowered or the engine oil is diluted, whereas the electric heater 24 does not have such a problem. Therefore, in this embodiment, the DOC 22 and the DPF 23 are actively used. As a measure for the activation, the heating of the DOC 22 by the electric heater 24 is a main measure, and an increase in the exhaust gas temperature by the post injection is an auxiliary measure. This exhaust purification control operation will be described in detail later.

  Returning to FIG. 1, an EGR passage 30 is disposed between the exhaust passage 20 upstream of the DOC 22 and the intake passage 10 downstream of the throttle valve 12. The EGR passage 30 is a passage for returning a part of the exhaust gas flowing through the exhaust passage 20 to the intake passage 10. An EGR valve 31 is disposed in the EGR passage 30. The EGR valve 31 controls the amount of exhaust gas recirculated from the exhaust passage 20 to the intake passage 10 by adjusting the cross-sectional area of the EGR passage 30 according to the opening degree. The exhaust gas recirculated to the intake passage 10 joins fresh air flowing from the upstream side of the intake passage 10 and flows into the cylinder 2.

  FIG. 3 is a block diagram of an electric system of the engine according to the present embodiment. As shown in FIG. 3, the electric system of the engine according to the present embodiment stores an alternator (corresponding to the power generation device of the present invention) 50 that generates power by obtaining power from the engine, and stores the electric power generated by the alternator 50. Capacitor (corresponding to the power storage device of the present invention) 51, the electric heater 24 for heating the DOC 22, an in-vehicle electric device 52 other than the electric heater 24 such as an audio or an air conditioner, the capacitor 51 and the in-vehicle electric device And a DC / DC converter 53 interposed between the starter motor 52 and a starter motor 55 for applying a rotational force to the engine when the engine is started.

  The electric system further includes a battery 54 that is mainly used as a power source for the starter motor 55. On the other hand, the capacitor 51 is mainly used as a power source for the electric heater 24 and the in-vehicle electric device 52.

  As shown in FIG. 3, the alternator 50 and the capacitor 51 are electrically connected to each other. Therefore, the power generated by the alternator 50 can be supplied to the capacitor 51. The electric heater 24 is electrically connected to the alternator 50 and the capacitor 51 via the heater relay 24a. Therefore, when the heater relay 24 a is turned on, the stored power of the capacitor 51 or the generated power of the alternator 50 can be supplied to the electric heater 24.

  Further, the battery 54 and the starter motor 55 are electrically connected to each other via the starter relay 56. Therefore, when the starter relay 56 is turned on, the stored power of the battery 54 can be supplied to the starter motor 55. The battery 54 and the in-vehicle electric device 52 are electrically connected to each other. Therefore, the stored power of the battery 54 can be supplied to the in-vehicle electric device 52.

  The capacitor 51 and the alternator 50, the in-vehicle electric device 52 and the battery 54 are electrically connected to each other via the DC / DC converter 53. A bypass circuit 53b that bypasses the DC / DC converter 53 is provided, and a bypass relay 53a is interposed in the bypass circuit 53b. Therefore, when the bypass relay 53 a is turned off, the stored power of the capacitor 51 or the generated power of the alternator 50 can be stepped down by the DC / DC converter 53 and supplied to the in-vehicle electric device 52 and the battery 54. On the other hand, the bypass relay 53a is turned on after waiting until the generated voltage of the alternator 50 reaches the rated voltage of the in-vehicle electric device 52. When the bypass relay 53 a is turned on, the generated power of the alternator 50 with the reduced generated voltage can be supplied to the in-vehicle electric device 52 and the battery 54 without passing through the DC / DC converter 53. In addition, a disconnect relay 26 is provided between the capacitor 51, the alternator 50 and the electric heater 24, and the DC / DC converter 53 and the bypass circuit 53b.

  The alternator 50 is connected to the crankshaft 4 (see FIG. 1) via a winding transmission member such as a belt in order to obtain power from the engine. The alternator 50 includes a rotor that rotates in conjunction with the crankshaft 4 and a stator coil that is disposed around the rotor (both not shown). A field coil for generating a magnetic field is wound around the rotor. During power generation, an electric current is applied to the field coil, and the rotor rotates in a magnetic field generated thereby, so that an induced current is generated in the stator coil.

  The alternator 50 includes a rectifier 50a that converts an alternating current into a direct current. The alternating current generated by the alternator 50 is converted to direct current by the rectifier 50a and then supplied to the capacitor 51 side.

  The capacitor 51 is an electric double layer capacitor (EDLC). Unlike the secondary battery such as the battery 54, such a capacitor 51 stores electricity by physical adsorption of electrolyte ions. Therefore, the capacitor 51 has a small internal resistance and can be charged and discharged relatively quickly. is there.

  The battery 54 is a secondary battery made of a general lead storage battery or the like as a vehicle-mounted battery. Since such a battery 54 stores electrical energy by a chemical reaction, it is not suitable for rapid charge / discharge, but has a characteristic that it can store a relatively large amount of electric power.

  In the present embodiment, the alternator 50 has an adjustable power generation voltage and can generate a maximum power of 25V. The capacitor 51 can store electric power of a maximum of 25 V and supply it to the outside. The battery 54 can supply a maximum of 14V to the outside. The onboard electric device 52 has a rated voltage of 14V, and the electric heater 24 has a rated voltage of 25V.

  Therefore, the electric power of 25 V stored in the capacitor 51 is supplied to the in-vehicle electric device 52 and the battery 54 by being stepped down to, for example, 12 V by the DC / DC converter 53, while being supplied to the electric heater 24. Can be supplied as it is at 25 V without going through the DC / DC converter 53. On the other hand, the battery 54 can supply only electric power of maximum 14V to the electric heater 24. Therefore, when the capacitor 51 is used as the power source of the electric heater 24, the electric heater 24 generates heat more quickly than when the battery 54 is used, and the DOC 22 is quickly heated and activated.

  The starter relay 56 is turned on when the engine is started, and is turned off otherwise. When the starter relay 56 is turned on, the stored power of the battery 54 is supplied to the starter motor 55, and the starter motor 55 is driven. The starter motor 55 rotates a ring gear integrally attached to the crankshaft 4 and applies a rotational force to the engine.

  The vehicle according to the present embodiment is a vehicle having a so-called idle stop function in which the engine is automatically stopped under a predetermined condition even when the ignition is ON. Therefore, the starter motor 55 is driven not only when the ignition is switched from OFF to ON, but also when restarting the automatically stopped engine. Therefore, since the battery 54 is frequently used as a power source for the starter motor 55, if the battery 54 is also used as the power source for the in-vehicle electric device 52 and the power source for the electric heater 24, the amount of power stored in the battery 54 is significantly reduced. 54 progresses.

  In summary, in the present embodiment, the capacitor 51 is mainly used as a power source for the electric heater 24 and the in-vehicle electric device 52, and the battery 54 is mainly used as a power source for the starter motor 55. Thereby, the advantage that DOC22 can be activated rapidly and deterioration of the battery 54 can be suppressed is acquired.

  Next, the time when the alternator 50 generates power will be described. As shown in FIG. 3, a transmission 40 is connected to the engine body 1, and a drive shaft 41 and wheels 42 are provided on the output side of the transmission 40. During acceleration of the vehicle, the output torque of the engine is transmitted to the drive shaft 41 via the transmission 40, and the wheels 42 are rotationally driven. When the vehicle is decelerated, the engine is rotated by the wheels 42 and the drive shaft 41 that rotate by inertia.

  Power generation by the alternator 50 is concentrated when the vehicle is decelerated. Then, the generated power (regenerated power) at that time is temporarily stored in the capacitor 51. Since the capacitor 51 can be charged relatively quickly as described above, the regenerative power supplied from the alternator 50 can be stored within a limited deceleration time without throwing away the regenerative power (the capacitor 51 is, for example, 10 seconds). Almost fully charged). When the deceleration frequency of the vehicle is high, the alternator 50 frequently generates power and generates a large amount of power. And since the capacitor 51 fully stores it without wasting it, almost all of the electric power required during traveling of the vehicle is covered by regenerative electric power. For example, when the vehicle is traveling in an urban area, the acceleration / deceleration of the vehicle is frequently repeated. Therefore, in many cases, the vehicle decelerates again before the amount of power stored in the capacitor 51 significantly decreases, and the regenerative power is reduced to the capacitor. 51.

  On the other hand, during acceleration of the vehicle, in order to minimize the resistance torque applied to the engine from the alternator 50, power generation by the alternator 50 is basically not performed. At this time, power supply to the in-vehicle electric device 52 is covered by the stored power of the capacitor 51 and the stored power of the battery 54 as necessary.

  As described above, in the electric system of the present embodiment, power generation by the alternator 50 is performed intensively when the vehicle is decelerated, and the obtained regenerative power is rapidly charged without being discarded by the capacitor 51. It is an electrical system that is good for the environment.

  FIG. 4 is a control system diagram of the engine according to the present embodiment centering on a PCM (power-train control module) 60. As is well known, the PCM 60 is a microprocessor including a CPU, a ROM, a RAM, and the like, and corresponds to a control unit and an activation continuation unit of the present invention.

  Various information is input to the PCM 60 from a plurality of sensors provided in the vehicle. That is, the vehicle has a vehicle speed sensor SW1 for detecting the traveling speed of the vehicle, a brake sensor SW2 for detecting the operating force (depressing force) of the brake pedal (not shown), and a depression amount of the accelerator pedal (not shown). Accelerator opening sensor SW3 for detecting the corresponding accelerator opening, engine speed sensor SW4 (see FIG. 1) for detecting the rotational speed of crankshaft 4, and DOC temperature sensor for detecting the temperature of DOC22 SW5 (see FIG. 1: corresponding to the temperature detecting means of the present invention) and a capacitor voltage sensor SW6 for detecting the voltage (inter-terminal voltage) of the capacitor 51 are provided, and these sensors SW1 to SW6 and PCM 60 are provided. Electrically connected.

  The PCM 60 is electrically connected to the fuel injection valve 6, the heater relay 24a, the disconnect relay 26, the field coil of the alternator 50, the in-vehicle electrical device 52, the DC / DC converter 53, the bypass relay 53a, and the starter relay 56. Various control signals are output to these devices.

  For example, the PCM 60 controls the combustion of the engine so as to obtain an appropriate torque according to the traveling state of the vehicle based on various information input from the sensors SW1 to SW6, or according to the traveling state of the vehicle. The power generation amount of the alternator 50 is controlled, and the supply of regenerative power generated by the alternator 50 to the capacitor 51, the on-vehicle electric device 52, and the battery 54 is controlled.

  Since the vehicle according to the present embodiment is a vehicle with an idle stop function as described above, the PCM 60 automatically stops the engine under a predetermined condition and restarts the engine that has been automatically stopped.

  Further, as described above, the engine according to the present embodiment has excellent fuel efficiency, low exhaust gas temperature, and the DOC 22 and DPF 23 on the exhaust passage 20 are not easily activated. Therefore, the PCM 60 positively activates the DOC 22 and DPF 23. In order to activate the exhaust gas, the DOC 22 is forcibly heated mainly by the electric heater 24 and the exhaust gas temperature is increased by post injection. Next, this exhaust purification control operation performed by the PCM 60 will be described in detail.

(2) Specific Control <First Control Example>
FIG. 5 is a flowchart of an exhaust purification control operation performed by the PCM 60, and FIG. 6 is a time chart thereof. This time chart shows a case where the temperature of the DOC 22 on the exhaust passage 20 is lowered due to, for example, a fuel cut while the vehicle is running. In this case, in this embodiment, even if combustion is restarted, the activation of the DOC 22 is delayed because the exhaust gas temperature is relatively low. Therefore, in the present embodiment, in order to actively activate the DOC 22, the PCM 60 first forcibly heats the DOC 22 with the electric heater 24, and increases the exhaust gas temperature by post injection only when it is still insufficient ( Continue activation of DOC22). In addition, in that case, the PCM 60 uses the capacitor 51 that stores regenerative power as the power source of the electric heater 24 in order to activate the DOC 22 quickly, suppress deterioration of the battery 54, and further improve fuel efficiency. .

  That is, when the exhaust purification control starts, the PCM 60 measures the temperature of the DOC 22 after turning off the bypass relay 53a and turning on the disconnect relay 26 in step S1. The temperature of the DOC 22 is specified by information from the DOC temperature sensor SW5.

  Next, in step S2, the PCM 60 determines whether or not the temperature of the DOC 22 is lower than a predetermined threshold temperature. The PCM 60 proceeds to step S9 when the determination is NO, and proceeds to step S3 when the determination is YES.

  In step S3, the PCM 60 measures (or calculates) the consumption current of the in-vehicle electrical device 52 and the storage amount SOC (state of charge) of the capacitor 51. The consumption current of the in-vehicle electric device 52 and the charged amount SOC of the capacitor 51 are specified by information from the capacitor voltage sensor SW6.

  Next, in step S4, the PCM 60 sets the stored amount SOC of the capacitor 51 to a predetermined caution stored amount SOC1 (corresponding to the threshold stored amount of the present invention) based on the current consumption of the in-vehicle electrical device 52 and the stored amount SOC of the capacitor 51. The energizable time Th0 to the electric heater 24 until it decreases is calculated. That is, the energizable time Th0 continues to supply electric power from the capacitor 51 to the in-vehicle electric device 52 that is currently supplying electric power from the capacitor 51, and newly supplies electric power to the electric heater 24 from the capacitor 51 as well. This is the time required for the storage amount SOC of the capacitor 51 to decrease to the caution storage amount SOC1 when the supply starts. This energizable time Th0 is determined from the current storage amount SOC of the capacitor 51, the caution storage amount SOC1, the current consumption of the in-vehicle electric device 52, and the power consumption of the electric heater 24.

  Next, in step S5, the PCM 60 energizes the electric heater 24 from the capacitor 51 for the energizable time Th0. That is, the heater relay 24 a is turned on to supply the stored power of the capacitor 51 to the electric heater 24.

  As a result, when the temperature of the DOC 22 is lower than the threshold temperature, the DOC 22 is forcibly heated by the electric heater 24. Therefore, even if the activation of the DOC 22 is delayed, the DOC 22 is actively activated. Can be made.

  In addition, at this time, when the electric heater 24 is also energized from the capacitor 51 from the current consumption current of the in-vehicle electrical device 52 and the storage amount SOC of the capacitor 51, the storage amount SOC of the capacitor 51 decreases to the caution storage amount SOC1. The energization possible time Th0 to the electric heater 24 is calculated, and the electric power is supplied from the capacitor 51 to the electric heater 24 for the calculated energization possible time Th0. Therefore, even if the electric heater 24 is used, the storage amount SOC of the capacitor 51 is greatly increased. Even if the power storage amount SOC decreases, the power storage amount SOC of the capacitor 51 does not decrease beyond the caution power storage amount SOC1, and power shortage to the in-vehicle electrical device 52 is avoided. Therefore, the power supply to the electric heater 24 and the power supply to the other on-vehicle electric device 52 are stably covered by the single capacitor 51.

  Next, the PCM 60 measures the temperature of the DOC 22 in step S6, and determines whether or not the temperature of the DOC 22 is lower than the threshold temperature in step S7. The PCM 60 proceeds to step S9 when the determination is NO, and proceeds to step S8 when the determination is YES.

  In step S8, the PCM 60 performs post-injection in which fuel is injected in the expansion stroke after main injection in which fuel is injected near the top dead center of the compression stroke, and returns to step S6 (operation for continuing activation of the DOC 22). .

  As a result, the temperature of the exhaust gas flowing into the DOC 22 is increased by post-injection, so that the energization of the electric heater 24 is stopped to avoid overdischarge of the capacitor 51, and the post-injection is also performed after the energization of the electric heater 24 is stopped. Activation of DOC22 can be continued. Therefore, the function of DOC22 (function to promote the oxidation reaction) is reliably recovered.

  The PCM 60 proceeds to step S9 when the temperature of the DOC 22 is equal to or higher than the threshold temperature in step S2 or S7. However, in this step S9, the temperature of the DOC 22 is equal to or higher than the threshold temperature, that is, the activation temperature or higher. The energization state of the electric heater 24 is confirmed. If it is in the ON state, the energization to the electric heater 24 is turned off in step S10, and then the process returns to step S1, and if it is in the OFF state, the process returns to step S1.

  In FIG. 6, until time t <b> 1, power is supplied from the capacitor 51 only to the in-vehicle electric device 52. Therefore, the charged amount SOC of the capacitor 51 is slowly decreased due to power supply only to the in-vehicle electric device 52. When the temperature of the DOC 22 falls below the threshold temperature at time t1, the electric heater 24 is turned on for the energizable time Th0. Since the electric power consumption of the electric heater 24 is large, the storage amount SOC of the capacitor 51 rapidly decreases after time t1. In addition, at a predetermined time after time t1, the temperature of the DOC 22 has started to rise due to the heating of the DOC 22 by the electric heater 24.

  At time t2 when the energizable time Th0 has elapsed, the electric heater 24 is turned off. At time t2, the charged amount SOC of the capacitor 51 is reduced to the caution charged amount SOC1. In the illustrated example, since the temperature of the DOC 22 has not yet risen to the threshold temperature at time t2, post-injection is executed after time t2 instead of heating the DOC 22 by the electric heater 24 (continuation of activation of the DOC 22). ). As a result, the temperature of the DOC 22 rises to the threshold temperature at time t3, and post-injection stops at time t3. The storage amount SOC of the capacitor 51 is slowly reduced after switching to power supply only to the in-vehicle electric device 52 after time t2.

<Second control example>
Compared to the first control example, the second control example is different because part of the exhaust purification control operation performed by the PCM 60 (more specifically, the operation of continuing the activation of the DOC 22) is different, and the other is the same. Only the part will be described, and the description of the same part will be omitted.

  That is, as shown in FIG. 7, steps S11 to S17, S21, and S22 in the second control example are the same as steps S1 to S7, S9, and S10 in the first control example.

  When the determination in step S17 is YES, the PCM 60 determines in step S18 whether or not the charged amount SOC of the capacitor 51 is greater than or equal to a predetermined lower limit charged amount SOCX. This lower limit storage amount SOCX is an amount that is smaller than the caution storage amount SOC1, that is, a lower amount. When the charged amount SOC of the capacitor 51 falls below the lower limit charged amount SOCX, power is generated by the alternator 50 and the capacitor 51 is charged.

  The PCM 60 proceeds to step S19 when the determination in step S18 is YES, and proceeds to step S20 when the determination is NO.

  In step S19, the PCM 60 stops energization to a predetermined in-vehicle electric device 52 among the in-vehicle electric devices 52, continues energization to the electric heater 24, and returns to step S16.

  Thereby, since the rate of decrease in the amount of charge SOC of the capacitor 51 is slowed by stopping the energization of the predetermined on-vehicle electric device 52, by continuing the energization to the electric heater 24 while avoiding overdischarge of the capacitor 51, The activation of the DOC 22 can be continued by the electric heater 24. Therefore, the function of DOC22 (function to promote the oxidation reaction) is reliably recovered.

  Examples of the in-vehicle electrical device 52 whose power supply stop is determined in advance include those that have little influence on the running of the vehicle, and those related to temperature control that cannot be immediately detected by the occupant, such as an air conditioner, Examples include heaters.

  On the other hand, in step S20, the PCM 60 performs post injection that injects fuel in the expansion stroke after main injection that injects fuel in the vicinity of the top dead center of the compression stroke, and turns off the disconnection relay 26 to generate power from the alternator 50. To implement. Then, in step S23, the PCM 60 determines whether or not the capacitor 51 has recovered to a fully charged state. If NO, the PCM 60 repeatedly executes step S20. If YES, the process returns to step S11.

  As a result, the temperature of the exhaust gas flowing into the DOC 22 is increased by the post injection, so that the energization of the electric heater 24 is stopped, and the capacitor 51 is charged by the power generation of the alternator 50 to avoid overdischarge of the capacitor 51. Even after the energization of the heater 24 is stopped, the activation of the DOC 22 can be continued by post injection. Therefore, the function of DOC22 (function to promote the oxidation reaction) is reliably recovered.

  In FIG. 8, time t11 corresponds to time t1 in FIG. Since the temperature of the DOC 22 has not yet risen to the threshold temperature at the time t12 when the energizable time Th0 has elapsed, after the time t12, the number of the on-vehicle electric devices 52 that use the power of the capacitor 51 is reduced. 24 is continued (continuation of activation of DOC22). For this reason, after time t12, the rate of decrease in the charged amount SOC of the capacitor 51 is somewhat slower than before.

  In FIG. 8, since the temperature of the DOC 22 has not yet increased to the threshold temperature at time t13 when the charged amount SOC of the capacitor 51 has decreased to less than the lower limit charged amount SOCX, after time t13, instead of heating by the electric heater 24. , Post injection is performed (continuation of activation of DOC22). As a result, the temperature of the DOC 22 rises to the threshold temperature at time t14, and the post injection ends at time t14.

  In addition, after time t13, the disconnection relay 26 is turned off, power is generated by the alternator 50, and the capacitor 51 is charged. During this time, electric power is supplied from the battery 54 to the in-vehicle electrical device 52. At that time, when the amount of electricity stored in the battery 54 is small, power is supplied from the battery 54 to the in-vehicle electric device 52 in a state where the number of in-vehicle electric devices 52 that use power is reduced, and when the amount of electricity stored in the battery 54 is large. Electric power is supplied from the battery 54 to the in-vehicle electrical device 52 without reducing the number of in-vehicle electrical devices 52 that use power. Then, after the capacitor 51 is fully charged, electric power is supplied from the capacitor 51 to the in-vehicle electric device 52. At that time, power is supplied from the capacitor 51 to the in-vehicle electrical device 52 without reducing the number of in-vehicle electrical devices 52 that supply power. Therefore, the charged amount SOC of the capacitor 51 is slowly decreased after full charge.

<Third control example>
Compared to the first control example, the third control example is different because part of the exhaust purification control operation performed by the PCM 60 (more specifically, the operation for continuing the activation of the DOC 22) is different, and the other is the same. Only the part will be described, and the description of the same part will be omitted.

  That is, as shown in FIG. 9, steps S31 to S37, S39, and S40 in the third control example are the same as steps S1 to S7, S9, and S10 in the first control example.

  When the determination in step S37 is YES, the PCM 60 performs post injection that injects fuel in the expansion stroke after main injection that injects fuel in the vicinity of the top dead center in the compression stroke in step S38. The power is generated by the alternator 50 until the storage amount SOC rises to a predetermined recovery storage amount SOC2 (this recovery storage amount SOC2 is a value larger than the caution storage amount SOC1), the capacitor 51 is charged, and the process goes to step S33. Return. That is, again, the energizable time Th0 to the electric heater 24 is calculated based on the current consumption of the in-vehicle electric device 52 and the charged amount SOC of the capacitor 51, and the electric heater 24 is energized from the capacitor 51 for the calculated time.

  Accordingly, the DOC 22 can be continuously activated by the electric heater 24 by repeatedly energizing the electric heater 24 while avoiding overdischarge of the capacitor 51 by charging the capacitor 51. Therefore, the function of DOC22 (function to promote the oxidation reaction) is reliably recovered.

  Further, the activation of the DOC 22 can be continued by the post-injection while the capacitor 51 is being charged. Therefore, the function of DOC22 (function to promote the oxidation reaction) is reliably recovered.

  In FIG. 10, time t21 corresponds to time t1 in FIG. Since the temperature of the DOC 22 has not yet risen to the threshold temperature at the time t22 when the energizable time Th0 has elapsed, post-injection is executed instead of heating by the electric heater 24 after the time t22 (continuation of activation of the DOC 22). ). In addition, after time t22, power is generated by the alternator 50 and the capacitor 51 is charged. During this time, the in-vehicle electric device 52 is supplied with electric power from the battery 54 when the amount of electricity stored in the battery 54 is large, and is stepped down from the alternator 50 via the DC / DC converter 53 when the amount of electricity stored in the battery 54 is small. In other words, power is supplied (ie, the bypass relay 53a is maintained in an OFF state).

  At time t23 when the charged amount SOC of the capacitor 51 increases to the recovered charged amount SOC2, the post injection is stopped and the heating by the electric heater 24 is resumed (continuation of activation of the DOC 22). That is, the electric heater 24 is turned on only during the energizable time Th0. Thereafter, after time t24 when the energizable time Th0 elapses and time t25 when the charged amount SOC of the capacitor 51 rises to the recovered charged amount SOC2, the heating of the electric heater 24 and the repeated post-injection are performed (activation of the DOC22). ), At a predetermined time before the time t26 when the energizable time Th0 elapses, the temperature of the DOC 22 becomes equal to or higher than the threshold temperature, and the control ends at the time t26.

<Fourth control example>
Compared to the first control example, the fourth control example is different because part of the exhaust purification control operation performed by the PCM 60 (more specifically, the operation of continuing the activation of the DOC 22) is different, and the other is the same. Only the part will be described, and the description of the same part will be omitted.

  That is, as shown in FIG. 11, steps S41 to S47, S51, and S52 in the fourth control example are the same as steps S1 to S7, S9, and S10 in the first control example.

  When the determination in step S47 is YES, the PCM 60 determines in step S48 whether or not the charged amount SOC of the capacitor 51 is greater than or equal to a predetermined lower limit charged amount SOCX. This lower limit storage amount SOCX is an amount that is smaller than the caution storage amount SOC1, that is, a lower amount. When the charged amount SOC of the capacitor 51 falls below the lower limit charged amount SOCX, power is generated by the alternator 50 and the capacitor 51 is charged.

  The PCM 60 proceeds to step S49 when the determination in step S48 is YES, and proceeds to step S50 when the determination is NO.

  In step S49, the PCM 60 turns on the bypass relay 53a, generates power by the alternator 50, energizes the electric heater 24, and returns to step S46.

  That is, as described above, the alternator 50 can adjust the power generation voltage up to a maximum of 25V. Therefore, in the fourth control example, the alternator 50 generates power of 14V, which is the rated voltage of the in-vehicle electric device 52, for example. This is supplied to the electric heater 24 as it is, and also to the in-vehicle electric device 52 via the bypass circuit 53b (that is, not via the DC / DC converter 53), and the same 14V power is supplied as it is. It is. In other words, the PCM 60 energizes the in-vehicle electrical device 52 by reducing the power generation voltage of the alternator 50 and bypassing the DC / DC converter 53.

  Thereby, by energizing the electric heater 24 with the regenerative electric power generated by the alternator 50, the electric heater 24 can continue the activation of the DOC 22 while avoiding overdischarge of the capacitor 51. Therefore, the function of DOC22 (function to promote the oxidation reaction) is reliably recovered.

  On the other hand, in step S50, the PCM 60 performs post injection that injects fuel in the expansion stroke after main injection that injects fuel near the top dead center of the compression stroke, and returns to step S46.

  As a result, the temperature of the exhaust gas flowing into the DOC 22 is increased by post-injection, so that the energization of the electric heater 24 is stopped to avoid overdischarge of the capacitor 51, and the post-injection is also performed after the energization of the electric heater 24 is stopped. Activation of DOC22 can be continued. Therefore, the function of DOC22 (function to promote the oxidation reaction) is reliably recovered.

  In FIG. 12, time t31 corresponds to time t1 in FIG. Since the temperature of the DOC 22 has not yet risen to the threshold temperature at the time t32 when the energizable time Th0 has elapsed, the electric heater 24 generates electric power (14V) from the alternator 50 after the time t32. 24 is continued (continuation of activation of DOC22). Further, after time t32, the bypass relay 53a is turned on, and the generated power (14V) of the alternator 50 is also supplied to the in-vehicle electric device 52 via the bypass circuit 53b. Therefore, after time t32, since no power is taken out from the capacitor, the storage amount SOC of the capacitor 51 is kept equal to or higher than the lower limit storage amount SOCX.

  When the temperature of the DOC 22 rises to the threshold temperature at time t33 due to the continued heating of the DOC 22 by the electric heater 24, the alternator 50 stops generating power and the heating by the electric heater 24 stops. After this time t33, since electric power is supplied to the in-vehicle electrical device 52 via the battery 54, the charged amount SOC of the capacitor 51 is kept equal to or higher than the lower limit charged amount SOCX.

  Next, fifth to eighth control examples will be described. In the fifth to eighth control examples, the first to fourth control examples calculate the energization possible time Th0 from the charged amount SOC of the capacitor 51 in advance to the electric heater 24 in advance. The power storage amount SOC 51 is calculated (or measured), and whether or not the electric heater 24 can be energized is determined based on the result.

<Fifth control example>
The fifth control example corresponds to the first control example. The first control example calculates the energizable time Th0 to the electric heater 24, and from the capacitor 51 until the energizable time Th0 elapses. Although the electric heater 24 is energized, the difference is that the amount of charge SOC stored in the capacitor 51 is always calculated, and the others are the same.

  That is, as shown in FIG. 13, steps S61, S62, S66, and S67 in the fifth control example are the same as steps S1, S2, S9, and S10 in the first control example.

  When the determination in step 62 is YES, the PCM 60 calculates the consumption current of the in-vehicle electric device 52 and the storage amount SOC of the capacitor 51 in step S63.

  Next, in step S64, the PCM 60 determines whether or not the charged amount SOC of the capacitor 51 is equal to or greater than the caution charged amount SOC1 even after the electric heater 24 is energized.

  As a result, when it is determined YES in step S64 that the stored amount SOC of the capacitor 51 is equal to or greater than the caution stored amount SOC1, the PCM 60 turns on the heater relay 24a in step S65, and starts the onboard electric device from the capacitor 51. While the energization to 52 is maintained, the energization to the electric heater 24 is performed. Then, the process returns to step S61.

  On the other hand, when it is determined in step S64 that the stored amount SOC of the capacitor 51 is less than the caution stored amount SOC1, the PCM 60 determines in step S68 whether or not the energized state of the electric heater 24 is OFF. If the determination is YES, the process proceeds directly to step S70 to perform post injection, and if the determination is NO, the heater relay 24a is turned OFF in step S69 to turn off the electric heater 24. Then, it progresses to step S70 and performs post injection. Then, the process returns to step S61.

<Sixth control example>
The sixth control example corresponds to the second control example. Compared to the fifth control example, part of the exhaust gas purification control operation performed by the PCM 60 (more specifically, the operation of continuing the activation of the DOC 22). ) Are different and the others are the same, only the different parts will be described, and the description of the same parts will be omitted.

  That is, as shown in FIG. 14, steps S71 to S77 in the sixth control example are the same as steps S61 to S67 in the fifth control example.

  When the determination in step S74 is NO, the PCM 60 determines in step S78 whether or not the charged amount SOC of the capacitor 51 is equal to or greater than the lower limit charged amount SOCX.

  When the determination in step S78 is YES, the PCM 60 stops energization to the predetermined in-vehicle electric device 52 among the in-vehicle electric devices 52 and continues energization to the electric heater 24 in step S79. Return to.

  If the determination in step S78 is NO, the PCM 60 checks the energization state of the electric heater 24 in step S80, and if it is in the ON state, the energization to the electric heater 24 is turned off in step S81, and the process proceeds to step S82. If it is in the OFF state, the process proceeds to step S82.

  In step S82, the PCM 60 performs post-injection, turns off the disconnection relay 26, performs power generation by the alternator 50, executes post-injection until the capacitor 51 recovers to a fully charged state, and returns to step S71.

<Seventh control example>
The seventh control example corresponds to the third control example. Compared to the fifth control example, part of the exhaust gas purification control operation performed by the PCM 60 (more specifically, the operation of continuing the activation of the DOC 22). ) Are different and the others are the same, only the different parts will be described, and the description of the same parts will be omitted.

  That is, as shown in FIG. 15, steps S91 to S97 in the seventh control example are the same as steps S61 to S67 in the fifth control example.

  If the determination in step S94 is NO, the PCM 60 confirms the energization state of the electric heater 24 in step S98. If it is in the ON state, the PCM 60 turns off the energization of the electric heater 24 in step S99, and then proceeds to step S100. If it is in the OFF state, the process proceeds to step S100.

  In step S100, the PCM 60 performs power generation by the alternator 50 until the charged amount SOC of the capacitor 51 rises to the recovered charged amount SOC2 while performing post injection, charges the capacitor 51, and returns to step S91.

<Eighth control example>
The eighth control example corresponds to the fourth control example. Compared to the fifth control example, part of the exhaust gas purification control operation performed by the PCM 60 (more specifically, the operation of continuing the activation of the DOC 22). ) Are different and the others are the same, only the different parts will be described, and the description of the same parts will be omitted.

  That is, as shown in FIG. 16, steps S101 to S107 in the eighth control example are the same as steps S61 to S67 in the fifth control example.

  When the determination in step S104 is NO, the PCM 60 determines in step S108 whether or not the charged amount SOC of the capacitor 51 is equal to or greater than the lower limit charged amount SOCX.

  If the determination in step S108 is YES, the PCM 60 turns on the bypass relay 53a in step S109, generates power by the alternator 50, energizes the electric heater 24, and returns to step S101.

  When the determination in step S108 is NO, the PCM 60 confirms the energization state of the electric heater 24 in step S110. If it is in the ON state, the PCM 60 turns off the energization of the electric heater 24 in step S111, and then proceeds to step S112. If it is in the OFF state, the process proceeds to step S112.

  In step S112, the PCM 60 performs post injection, and returns to step S101.

<Ninth control example>
Next, a ninth control example will be described. The ninth control example corresponds to the first control example, whereas the first control example energizes the electric heater 24 from the capacitor 51 until the energizable time Th0 elapses. Even if the energizable time Th0 has not elapsed, when the temperature of the DOC 22 rises to the threshold temperature, the difference is that the energization to the electric heater 24 is stopped, and the others are the same. Description of the portion is omitted.

  That is, as shown in FIG. 17, steps S121 to S124, S130, and S131 in the ninth control example are the same as steps S1 to S4, S9, and S10 in the first control example.

  After step S124, the PCM 60 starts energization from the capacitor 51 to the electric heater 24 in step S125.

  Next, the PCM 60 measures the temperature of the DOC 22 in step S126, and determines whether or not the temperature of the DOC 22 is lower than the threshold temperature in step S127.

  When the determination in step S127 is NO, that is, when the temperature of the DOC 22 is equal to or higher than the threshold temperature (when the temperature of the DOC 22 rises to the threshold temperature), the PCM 60 sets the energization time to the electric heater 24 to the energizable time Th0. Even if not, the power supply to the electric heater 24 is stopped in steps S130 to S131.

  When the determination in step S127 is YES, that is, when the temperature of the DOC 22 is lower than the threshold temperature (when the temperature of the DOC 22 has not risen to the threshold temperature), the PCM 60 has passed the energizable time Th0 in step S128. It is determined whether or not.

  When the determination in step S128 is NO, that is, when the energization time to the electric heater 24 has not reached the energization possible time Th0, the PCM 60 returns to step S126 while energizing the electric heater 24 is kept on.

  When the determination in step S128 is YES, that is, when the energization time to the electric heater 24 has reached the energizable time Th0, the PCM 60 turns off the energization to the electric heater 24 in step S129, The injection is executed, and the process returns to step S126.

(3) Operation As described above, the engine exhaust purification control apparatus according to the present embodiment controls the exhaust purification apparatus provided in the exhaust passage 20 of the engine, and has the following characteristic configuration. I have.

  That is, an electric heater 24 for heating the DOC 22 on the exhaust passage 20, an in-vehicle electric device 52 other than the electric heater 24, a capacitor 51 for supplying electric power to the electric heater 24 and the in-vehicle electric device 52, A DOC temperature sensor SW5 that detects temperature and a PCM 60 that is a microprocessor are provided.

  When power is supplied only from the capacitor 51 to the in-vehicle electrical device 52 and the temperature detected by the DOC temperature sensor SW5 is lower than a predetermined threshold temperature, the PCM 60 has a storage amount SOC of the capacitor 51 of a predetermined attention storage. The in-vehicle electric device 52 and the electric heater 24 are energized from the capacitor 51 until the amount SOC1 is reduced. Furthermore, after energizing the electric heater 24, the PCM 60 continues to activate the DOC 22 when the temperature detected by the DOC temperature sensor SW5 is lower than the threshold temperature.

  According to the present embodiment, when the temperature of the DOC 22 provided in the exhaust passage 20 is lower than a predetermined threshold temperature, the electric heater 24 for heating the DOC 22 is energized. Even when the DOC 22 is difficult to be activated, the DOC 22 can be actively activated.

  At this time, since the capacitor 51 is energized to the electric heater 24 until the charged amount SOC of the capacitor 51 decreases to a predetermined caution charged amount SOC1, even if the electric heater 24 is used, the charged amount SOC of the capacitor 51 is greatly increased. Even if the voltage drops to a lower value, it does not drop below the caution charge amount SOC1 and the power shortage to the in-vehicle electric device 52 is avoided. Therefore, the power supply to the electric heater 24 and the power supply to the other on-vehicle electric device 52 are stably covered by the single capacitor 51.

  Furthermore, after the energization of the electric heater 24, when the temperature of the DOC 22 has not yet risen to the threshold temperature, the activation of the DOC 22 is continued, so that the function of the DOC 22 is reliably recovered.

  In particular, in the first to fourth and ninth control examples, if it is assumed that electric power is also supplied from the capacitor 51 to the electric heater 24, the amount of charge SOC of the capacitor 51 is reduced to the caution charge amount SOC1. The energizable time Th0 to the electric heater 24 is calculated from the current storage amount SOC of the capacitor 51 and the consumption current of the in-vehicle electric device 52. From the capacitor 51 to the in-vehicle electric device 52 until the calculated energized time Th0 elapses. Because the electric heater 24 is energized, even if the amount of charge SOC of the capacitor 51 is significantly reduced by using the electric heater 24, the electric charge is not reduced below the caution charge amount SOC1. Power shortage is avoided. Therefore, the power supply to the electric heater 24 and the power supply to the other on-vehicle electric device 52 are stably covered by the single capacitor 51.

  Further, in the first to fourth and ninth control examples, during the energization of the electric heater 24, it is determined whether or not the charged amount SOC of the capacitor 51 has decreased to the caution charged amount SOC1 (SOC> SOC1). There is no need.

  In the fifth to ninth control examples, since the energization to the electric heater 24 is stopped when the temperature of the DOC 22 rises to the threshold temperature during the energization of the electric heater 24, the DOC 22 is energized during the energization of the electric heater 24. When the temperature reaches the threshold temperature, useless waste of the charged amount SOC of the capacitor 51 is avoided.

  In the first, fifth, and ninth control examples, after the energization of the electric heater 24, when the temperature detected by the DOC temperature sensor SW5 is lower than the threshold temperature, the post injection for injecting the fuel in the expansion stroke is performed. Since it is executed, the temperature of the exhaust gas flowing into the DOC 22 is increased by the post injection. Therefore, the activation of the DOC 22 can be continued by post-injection even after the energization of the electric heater 24 is stopped while the energization of the electric heater 24 is stopped to avoid overdischarge of the capacitor 51.

  In the second and sixth control examples, after energization of the electric heater 24, when the temperature detected by the DOC temperature sensor SW5 is lower than the threshold temperature, to the predetermined on-vehicle electric device 52 among the on-vehicle electric devices 52. Since the energization of the electric heater 24 is stopped, the energization of the electric heater 24 is continued. Therefore, the energization of the predetermined on-vehicle electric device 52 is stopped, so that the rate of decrease in the charged amount SOC of the capacitor 51 becomes slow. Therefore, the activation of the DOC 22 can be continued by the electric heater 24 by continuing energization to the electric heater 24 while avoiding overdischarge of the capacitor 51.

  In the third and seventh control examples, after energizing the electric heater 24, when the temperature detected by the DOC temperature sensor SW5 is lower than the threshold temperature, the capacitor 51 is charged, and the electric heater 24 is energized again. Therefore, the DOC 22 can be continuously activated by the electric heater 24 by repeatedly energizing the electric heater 24 while avoiding overdischarge of the capacitor 51 by charging the capacitor 51.

  In the third and seventh control examples, since the post-injection in which the fuel is injected in the expansion stroke is performed while the capacitor 51 is being charged, the activation of the DOC 22 is continued by the post-injection while the capacitor 51 is being charged. be able to.

  In the fourth and eighth control examples, after the energization of the electric heater 24, when the temperature detected by the DOC temperature sensor SW5 is lower than the threshold temperature, the alternator 50 generates power, and the generated power is Since the heater 24 is energized, it is possible to continue the activation of the DOC 22 by the electric heater 24 while avoiding overdischarge of the capacitor 51 by energizing the electric heater 24 with the electric power generated by the alternator 50. .

  In the fourth and eighth control examples, the on-vehicle electric device 52 is energized while the generated voltage of the alternator 50 is reduced and the DC / DC converter 53 is bypassed. Is supplied without going through the DC / DC converter 53. Therefore, power consumption by the DC / DC converter 53 can be suppressed.

(4) Other Embodiments In the above embodiment, the exhaust purification device to be heated by the electric heater 24 is the DOC 22. In other words, activating the DOC 22 promotes the oxidation reaction of the exhaust gas, purifies CO and HC in the exhaust gas, raises the exhaust gas temperature by the heat of the oxidation reaction, and self-regenerates (captures) the downstream DPF 23. Function of burning and removing the collected particulates).

  However, the present invention is not limited to this, and the exhaust purification device to be heated by the electric heater 24 may be the DPF 23 with catalyst. That is, by activating a catalyst such as platinum carried by the DPF 23, the oxidation reaction of the exhaust gas can be promoted, the temperature of the exhaust gas can be raised by the heat of the oxidation reaction, and the self-regeneration function of the DPF 23 can be assisted.

  And in any case, in order to activate DOC22 or DPF23 with a catalyst in post injection, fuel was injected in the expansion stroke and the exhaust gas temperature which flows into DOC22 or DPF23 with a catalyst was raised.

  However, regarding the activation of the DPF 23 after the activation of the DOC 22, the post injection may inject the fuel in the exhaust stroke. The fuel injected in the exhaust process flows into the DOC 22 without being burned and burns in the DOC 22, so that an extremely high temperature exhaust gas flows into the DPF 23. Therefore, the activation of the DPF 23 with catalyst and the self-regeneration function of the DPF 23 can be assisted.

  In the embodiment, the engine is a diesel engine in which fuel self-ignites. However, the present invention is not limited to this, and a spark ignition type gasoline engine or the like may be used. In this case, a three-way catalyst is provided in the exhaust passage as an exhaust purification device, and the three-way catalyst is heated by an electric heater. In the post-injection, the ignition timing is retarded, the combustion timing is delayed, and the exhaust gas whose temperature is higher than usual is caused to flow into the three-way catalyst.

  In each control example, instead of measuring the temperature of the exhaust purification device, the temperature of the exhaust gas flowing into the exhaust purification device may be measured.

  In step S19 of the second control example and step S79 of the sixth control example, the energization may be suppressed instead of stopping the energization to the predetermined in-vehicle electric device 52.

  The time charts (FIGS. 6, 8, 10, and 12) of each control example are examples, and are not limited to these.

  Although the time chart of each control example was when the exhaust gas purification device was cooled while the vehicle was running, the flowchart (FIGS. 5, 7, 9, 11, 13 to 17) of each control example shows the engine It can also be applied at start-up. Unlike when the vehicle is running, the exhaust purification device has not been activated at the time of engine startup, so the activation of the exhaust purification device continues (steps S8, S19, S20, S38, S49, S50, S70, S79). , S82, S100, S109, S112, S129), the function of the exhaust emission control device is reliably realized.

20 Exhaust passage 22 DOC (Exhaust gas purification device)
23 DPF (exhaust gas purification device)
24 Electric heater (heating device)
50 Alternator (power generator)
51 Capacitor (power storage device)
52 On-vehicle electrical device 53 DC / DC converter 53b Bypass circuit 60 PCM (control means, activation continuation means)
SOC1 Attention charge amount (threshold charge amount)
SW5 DOC temperature sensor (temperature detection means)
Th0 Energized time

Claims (9)

An exhaust purification control device for an engine that controls an exhaust purification device provided in an exhaust passage of the engine,
A heating device for heating the exhaust purification device;
An in-vehicle electrical device other than the heating device;
A power storage device for supplying power to the heating device and the in-vehicle electric device;
Temperature detecting means for detecting the temperature of the exhaust purification device;
When the temperature detected by the temperature detection unit is lower than a predetermined threshold temperature in a state where electric power is supplied only from the power storage device to the in-vehicle electric device, the power storage amount of the power storage device becomes a predetermined threshold power storage amount. Control means for energizing the in-vehicle electric device and the heating device from the power storage device until the power decreases,
After the energization of the heating device by the control means, there is provided an activation continuation means for continuing the activation of the exhaust emission control device when the temperature detected by the temperature detection means is lower than the threshold temperature. An exhaust purification control apparatus for an engine characterized by comprising: The engine exhaust gas purification control device according to claim 1,
The control means may energize the heating device until the amount of electricity stored in the electricity storage device drops to the threshold amount of electricity, assuming that power is also supplied from the electricity storage device to the heating device. The current storage amount of the power storage device and the current consumption of the in-vehicle electric device are calculated, and the in-vehicle electric device and the heating device are energized from the power storage device until the calculated time elapses. An engine exhaust gas purification control device. The engine exhaust gas purification control apparatus according to claim 1 or 2,
The control unit is configured to stop energization of the heating device when the temperature detected by the temperature detection unit rises to the threshold temperature during energization of the heating device. Engine exhaust purification control device. The engine exhaust gas purification control device according to any one of claims 1 to 3,
The engine exhaust purification control apparatus according to claim 1, wherein the activation continuation means performs post injection in which fuel is injected between an expansion stroke and an exhaust stroke. The engine exhaust gas purification control apparatus according to any one of claims 1 to 4,
The activation continuation means suppresses or stops energization to a predetermined on-vehicle electric device among the on-vehicle electric devices, and continues energization to the heating device, wherein the exhaust gas purification of the engine is characterized in that Control device. The engine exhaust gas purification control device according to any one of claims 1 to 5,
The engine exhaust purification control apparatus, wherein the activation continuation means charges the power storage device and energizes the heating device again. The engine exhaust gas purification control apparatus according to claim 6,
The engine exhaust gas purification control apparatus according to claim 1, wherein the activation continuation means performs post injection for injecting fuel between an expansion stroke and an exhaust stroke during charging of the power storage device. The engine exhaust gas purification control apparatus according to any one of claims 1 to 7,
The engine exhaust purification control apparatus, wherein the activation continuation means causes the power generation apparatus to generate power and energizes the heating device with the generated power. The engine exhaust gas purification control apparatus according to claim 8,
The engine exhaust gas purification control apparatus according to claim 1, wherein the activation continuation unit is configured to energize the in-vehicle electric device while reducing the generated voltage and energizing the DC / DC converter by bypassing.

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