TW202210710A - Exhaust gas treatment system of series hybrid vehicle capable of suppressing the emission of unpurified exhaust gas - Google Patents

Abstract

The invention aims to suppress the emission of unpurified exhaust gas. When there is a request to start an engine, an ECU operates an EHC heater to warm up the EHC three-way catalytic converter (S3). Further, the ECU makes a switching valve in a first state (S5). When the three-way catalytic converter is activated, the ECU starts the engine and operates the engine in the first operation (S7, S9). The exhaust gas at this time flows through a bypass passage and is purified by the three-way catalytic converter, and then flows into an exhaust gas treatment device to warm up the NOx purification catalyst. When the NOx purification catalyst is activated, the ECU sets the switching valve to the second state (S11, S13) and switches the engine operation from the first operation to the second operation (S15).

Description

Exhaust treatment system for series hybrid vehicle

The present invention relates to an exhaust gas treatment system for a series hybrid vehicle equipped with an engine for power generation.

Japanese Patent Laid-Open No. 2018-178892 (Patent Document 1) discloses a catalyst warm-up device arranged on an exhaust passage of an internal combustion engine having a supercharger. The catalytic converter warm-up device has an exhaust gas bypass passage that bypasses the turbo of the supercharger and is connected to the exhaust gas passage upstream of the catalytic converter that purifies the exhaust gas. A heat generating portion is provided at a portion of the exhaust bypass valve that opens and closes the exhaust bypass passage and is in contact with the exhaust gas flowing in the exhaust bypass passage. The catalytic converter warm-up device warms up the catalytic converter early by passing the exhaust gas through the exhaust bypass passage and heating the exhaust gas by the heat generating part. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2018-178892

[Problems to be Solved by Invention]

However, in the catalyst warm-up device of Patent Document 1, unpurified exhaust gas may be discharged before the catalyst is activated by the warm-up.

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to suppress the discharge of unpurified exhaust gas. [Technical means to solve problems]

(1) The exhaust gas treatment system of the present invention is an exhaust gas treatment system of a series hybrid vehicle having an engine for power generation. An exhaust gas treatment system for a series hybrid vehicle includes: a first catalyst installed in an exhaust passage of an engine for power generation; a second catalyst installed upstream of the first catalyst in the exhaust passage; and a heating device , which is configured to be able to raise the temperature of the second catalyst or the exhaust gas flowing into the second catalyst; and a control device that controls the power generation engine and the temperature raising device. When there is a start request of the power generation engine, the control device operates the power generation engine in a normal operation mode after executing the warm-up control. In the warm-up control, the control device operates the temperature raising device to activate the second catalyst before starting the power generation engine, and after activating the second catalyst, the power generation engine is started to activate the first catalyst.

According to the above configuration, the exhaust gas treatment system includes the first catalyst, the second catalyst, and the temperature raising device configured to be able to raise the temperature of the second catalyst or the exhaust gas flowing into the second catalyst. When there is a request for starting the engine for power generation (ie, a request for power generation), the control device operates the heating device to activate the second catalyst before starting the engine for power generation. After activating the second catalyst, the control device starts the engine for power generation, and activates the first catalyst using the exhaust gas. The exhaust gas at this time is purified by the second catalyst, and then flows into the first catalyst to activate the first catalyst. Therefore, the discharge of unpurified exhaust gas to the outside of the vehicle can also be suppressed during the period before the activation of the first catalyst.

(2) In one embodiment, the first catalyst is configured to be able to purify the exhaust gas during normal operation. In addition, the heat capacity of the second catalytic converter is smaller than that of the first catalytic converter, and it is configured to purify exhaust gas during low-speed operation in which the power generation engine is operated at a lower rotational speed than normal operation. In the warm-up control, the control device operates the heating device to activate the second catalytic converter before starting the engine for power generation, starts the engine for power generation after activating the second catalytic converter, and operates the engine for power generation at a low speed. Then, the first catalytic converter is activated, and after the first catalytic converter is activated, the power generation engine is operated in the normal operation mode.

The temperature raising means should just have the performance which can raise the temperature of a 2nd catalyst. According to the above configuration, the heat capacity of the second catalyst is smaller than that of the first catalyst, and it is configured to be able to purify the exhaust gas during low-speed operation. Therefore, compared with the case where a temperature raising device for raising the temperature of the first catalyst is provided, for example, a low-performance and small-sized temperature raising device can be used, so that cost reduction and space saving can be achieved.

Furthermore, since the thermal capacity of the second catalytic converter is smaller than that of the first catalytic converter, the power consumption required for the activation of the catalytic converter can be reduced as compared with the case where the temperature riser is used to activate the first catalytic converter.

(3) In one embodiment, the second catalytic converter is a three-way catalytic converter. In the warm-up control, the control device operates the heating device to activate the second catalytic converter before starting the power generation engine, starts the power generation engine after activating the second catalytic converter, and operates the power generation engine at a low speed with The first catalyst is activated by operating so that the air-fuel ratio becomes the theoretical air-fuel ratio, and after activating the first catalyst, the power generation engine is operated in the normal operation mode.

According to the above configuration, the three-way catalytic converter is used for the second catalyst, and the power generation engine is operated so that the air-fuel ratio becomes the theoretical air-fuel ratio in the warm-up control. Generally speaking, since a three-way catalytic converter is cheaper than a Nox purifying catalyst, by using the three-way catalytic converter as the second catalyst, it is possible to suppress exhaust emissions compared with the case of using a Nox purifying catalyst. The cost of parts for the gas treatment system. In addition, in the warm-up control, the control device operates the power generation engine so that the air-fuel ratio becomes the theoretical air-fuel ratio, whereby the exhaust gas can be efficiently purified by the ternary catalytic converter.

(4) In one embodiment, the power generation engine includes a turbocharger. The first catalyst is provided in the exhaust passage downstream of the turbine of the turbocharger. The exhaust gas treatment system of the series hybrid vehicle further includes: a bypass passage that branches from the exhaust passage upstream of the turbine, bypasses the turbine and merges with the exhaust passage upstream of the first catalyst; and a switching valve, It is configured to be switchable between a first state in which the exhaust gas flows through the bypass passage and a second state in which the exhaust gas does not flow through the bypass passage. The second catalyst and the temperature raising device are provided in the bypass passage. In the warm-up control, the control device sets the switching valve to the first state before the activation of the first catalytic converter, and sets the switching valve to the second state when the first catalytic converter is activated.

When a bypass passage is not provided, but a second catalytic converter is provided in the exhaust passage upstream of the turbine, for example, during normal operation, the second catalytic converter is used to throttle the airflow of the exhaust gas to generate a pressure drop, thereby causing a pressure drop. There is a possibility of a boost delay. According to the above configuration, the exhaust gas treatment system is provided with a bypass passage that bypasses the turbine, and the second catalyst is provided in the bypass passage. Then, the exhaust gas is bypassed by the bypass passage before the first catalyst is activated, and the exhaust gas is caused to flow to the turbine when the first catalyst is activated. That is, during the normal operation of the power generation engine, the exhaust gas flows to the turbine without passing through the second catalyst. Thereby, since it is possible to avoid the occurrence of a pressure drop caused by throttling the flow of exhaust gas by the second catalyst during normal operation, it is possible to suppress the occurrence of a supercharging delay.

(5) In one embodiment, the temperature increasing device is an electric heater provided in contact with the second catalyst. In the warm-up control, before starting the engine for power generation, the control device operates the electric heater to heat up and activate the second catalyst, and after activating the second catalyst, the engine for power generation is started, and the first catalyst is activated. activation.

According to the above configuration, when there is a request to start the power generation engine, the control device activates the second catalyst by operating the electric heater provided in contact with the second catalyst before starting the power generation engine. After activating the second catalyst, the control device starts the engine for power generation, and activates the first catalyst using the exhaust gas. The exhaust gas at this time is purified by the second catalyst, and then flows into the first catalyst to activate the first catalyst. Therefore, it is possible to suppress the discharge of unpurified exhaust gas to the outside of the vehicle before the activation of the first catalyst.

(6) In one embodiment, the exhaust gas treatment system of the series hybrid vehicle further includes a rotary electric machine connected to a crankshaft of an engine for power generation. The temperature-raising device is an electric heater that is installed in the exhaust passage upstream of the second catalyst and that heats the exhaust gas. In the warm-up control, before starting the engine for power generation, the control device uses a rotating electrical machine to drive the engine for power generation, operates an electric heater to raise the temperature of the exhaust gas, activates the second catalyst, and then activates the second catalytic converter. After the activation of the second catalyst, the power generation engine is started to activate the first catalyst.

According to the above configuration, when there is a request to start the power generation engine, the control device uses the rotary electric machine connected to the crankshaft of the power generation engine to motor-drive the power generation engine, and uses the electric heater to heat up the exhaust gas generated thereby. The heated exhaust gas flows into the second catalyst to activate the catalyst. Since the exhaust gas driven by the electric motor does not contain NOx or the like, it is possible to suppress the discharge of unpurified exhaust gas to the outside of the vehicle even before the activation of the second catalyst. Then, after the activation of the second catalyst, the engine for power generation is started, and the first catalyst is activated by the exhaust gas. At this time, since the exhaust gas flowing into the first catalyst is purified by the second catalyst, it is possible to suppress the discharge of unpurified exhaust gas to the outside of the vehicle even before the activation of the first catalyst.

(7) In a certain embodiment, the control apparatus operates the engine for power generation at the maximum thermal efficiency point at which the thermal efficiency of the engine for power generation becomes the maximum during normal operation.

In the series hybrid vehicle, since the engine is provided as an engine for power generation, the operating point of the engine can be appropriately controlled regardless of the running state of the vehicle. During normal operation, the efficiency can be improved by operating the power generation engine at the point of maximum thermal efficiency. [Effect of invention]

According to the present invention, the discharge of unpurified exhaust gas can be suppressed.

Hereinafter, Embodiment 1 will be described in detail with reference to the drawings. In addition, the same symbols are attached to the same or corresponding parts in the figures, and the description thereof will not be repeated.

[Embodiment 1] <Overall structure of the vehicle> FIG. 1 is a diagram schematically showing the overall configuration of a vehicle 300 according to the first embodiment. The vehicle 300 is a so-called series hybrid vehicle including the engine 1 for power generation. The vehicle 300 includes an engine 1, a first motor generator 2, a second motor generator 3, a power control unit (hereinafter also referred to as a "PCU (Power Control Unit)") 4, a transmission gear 5, a drive shaft 6, a battery 7, Monitoring unit 9 , ECU (Electronic Control Unit, electronic control unit) 200 , and battery ECU 250 . Furthermore, the vehicle 300 includes a DC (direct current)/DC converter 110 , an auxiliary battery 120 , and a low-voltage auxiliary device 130 .

The engine 1 is, for example, a common rail type diesel engine. Furthermore, as the engine 1, other types of diesel engines may also be used. The engine 1 of the first embodiment includes four cylinders 12 as shown in FIG. 2 below.

The first motor-generator 2 and the second motor-generator 3 are AC rotating electrical machines, respectively. The AC rotating electrical machine includes, for example, a permanent magnet type synchronous motor including a rotor in which permanent magnets are embedded.

The first motor generator 2 is connected to the crankshaft of the engine 1 . The first motor generator 2 uses the electric power of the battery 7 to rotate the crankshaft of the engine 1 when the engine 1 is started. In addition, the first motor generator 2 can generate electricity using the power of the engine 1 . The AC power generated by the first motor generator 2 is converted into DC power by the PCU 4 and charged into the battery 7 . In addition, the AC power generated by the first motor generator 2 may be supplied to the second motor generator 3 in some cases.

The rotor of the second motor generator 3 is mechanically connected to the drive shaft 6 via the transmission gear 5 . The second motor generator 3 rotates the drive shaft 6 using at least one of the electric power from the battery 7 and the electric power generated by the first motor generator 2 . In addition, the second motor generator 3 may generate electricity by regenerative braking during braking or when the acceleration decreases. The AC power generated by the second motor generator 3 is converted into DC power by the PCU 4 and charged into the battery 7 .

The PCU 4 converts the DC power stored in the battery 7 into AC power according to a control signal from the ECU 200 and supplies it to the first motor generator 2 and the second motor generator 3 . Moreover, the PCU 4 converts the AC power generated by the first motor generator 2 and the second motor generator 3 into DC power, and supplies it to the battery 7 . The PCU 4 is configured to be able to individually control the states (power running and regeneration) of the first motor-generator 2 and the second motor-generator 3 . The PCU 4 includes, for example, an inverter 4 a provided to the first motor generator 2 , an inverter 4 b provided to the second motor generator 3 , and an output voltage for boosting the DC voltage supplied to each inverter to the battery 7 Converter 4c above.

The battery 7 stores electric power for driving the vehicle 300 . The battery 7 includes a plurality of single cells 8 that are stacked. The unit cell 8 is, for example, a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. In addition, the unit cell 8 may be either a battery having a liquid electrolyte between the positive electrode and the negative electrode, or a battery having a solid electrolyte (all-solid-state battery). Furthermore, the battery 7 can also be a large-capacity capacitor.

The positive terminal of the battery 7 is electrically connected to the PCU 4 via the power line PL. The negative terminal of the battery 7 is electrically connected to the PCU 4 via the power line NL.

The monitoring unit 9 monitors the state of the battery 7 . Specifically, the monitoring unit 9 includes a voltage sensor for detecting the voltage of the battery 7 , a current sensor for detecting the current input and output relative to the battery 7 , and a temperature sensor for detecting the temperature of the battery 7 (all not shown in the figure). ). Each sensor outputs a signal indicating its detection result to battery ECU 250 .

The DC/DC converter 110 is electrically connected to the power lines PL and NL, and the voltage supplied from the power lines PL and NL is stepped down and supplied to the power line EL. That is, the DC/DC converter 110 steps down the output voltage of the battery 7 and generates electric power to be supplied to the auxiliary battery 120 and the low-voltage auxiliary device 130 . DC/DC converter 110 is controlled by ECU 200 .

The auxiliary battery 120 stores electric power for operating the low-voltage auxiliary device 130 mounted on the vehicle 300 . The auxiliary battery 120 includes, for example, a lead storage battery. The voltage of the auxiliary battery 120 is lower than the voltage of the battery 7, for example, about 12 V.

The low-voltage auxiliary device 130 includes a plurality of auxiliary devices mounted on the vehicle 300 . The auxiliary equipment includes, for example, audio equipment, video equipment, navigation equipment, and the following heater 77 ( FIG. 2 ). The low-voltage auxiliary device 130 is operated by receiving power supply from the battery 7 and the auxiliary battery 120 .

The ECU 200 includes a CPU (Central Processing Unit) 210 , a memory (RAM (Random Access Memory) and a ROM (Read Only Memory)) 220 , and is used to input various signals. Output I/O buffer (not shown). The CPU 210 expands and executes the program stored in the ROM in the RAM. The processing executed by the CPU 210 is described in the program stored in the ROM. The ECU 200 executes predetermined arithmetic processing by the CPU 210 based on various signals input from the input and output buffers and information stored in the memory 220 , and controls each device based on the arithmetic results to bring the vehicle 300 into a desired state. Furthermore, these controls are not limited to the processing by software, and post-processing can be constructed by using dedicated hardware (electronic circuit). The ECU 200 corresponds to the control device in the present invention.

ECU 200 controls various devices in vehicle 300 such as engine 1 , PCU 4 , and DC/DC converter 110 .

The battery ECU 250 includes a CPU, a memory, and an input/output buffer (none of which are shown) for inputting and outputting various signals. The battery ECU 250 is configured to be able to calculate the SOC (State Of Charge) of the battery 7 using detection results from various sensors of the monitoring unit 9 . As a method for calculating the SOC, for example, various well-known methods such as a method of integrating current values (coulomb counting) or a method of estimating an open circuit voltage (OCV: Open Circuit Voltage) can be employed. The battery ECU 250 monitors the SOC of the battery 7 , and when the SOC of the battery 7 is lower than a predetermined SOC, outputs a start request (in other words, a power generation request) of the engine 1 to the ECU 200 .

As the main control executed by the ECU 200 of the first embodiment, the warm-up control can be exemplified. The details of the warm-up control will be described later. The warm-up control is used to suppress the discharge of unpurified exhaust gas to the outside of the vehicle. For example, the ECU 200 executes the warm-up control after receiving the start request of the engine 1 . After the ECU 200 executes the warm-up control, the engine 1 is appropriately started, and the battery 7 is charged.

＜Structure of the engine＞ FIG. 2 is a diagram showing a schematic configuration of the engine 1 including the exhaust gas treatment system in the first embodiment. The engine 1 includes an engine body 10, an air cleaner 20, an intercooler 26, an intake manifold 28, an intake throttle valve 29, a supercharger 30, an exhaust manifold 50, an exhaust treatment device 56, and an exhaust gas A recirculation device (hereinafter also referred to as “EGR (Exhaust Gas Recirculation) device”) 60 .

The engine body 10 includes a plurality of cylinders 12 , a common rail 14 , and a plurality of injectors 16 . In Embodiment 1, the engine 1 is described by taking a tandem 4-cylinder engine as an example, but it may also be an engine with other cylinder layouts (for example, a V-type or a horizontal type).

The plurality of injectors 16 are fuel injection devices, and are respectively disposed in the plurality of cylinders 12 and are respectively connected to the common rail 14 . In the common rail 14, fuel in a high-pressure state after being pressurized by a high-pressure pump (not shown) is stored. The plurality of injectors 16 are supplied with high pressure fuel stored in the common rail 14 . The plurality of injectors 16 operate according to the control signals IJ1 to IJ4 from the ECU 200 to inject fuel into the respective cylinders 12 .

The air cleaner 20 removes foreign matter in the air drawn in from the outside of the engine 1 . One end of the first intake passage 22 is connected to the air cleaner 20 .

An intake air inlet of the compressor 32 of the supercharger 30 is connected to the other end of the first intake passage 22 . One end of the second intake passage 24 is connected to the intake air outlet of the compressor 32 . The compressor 32 supercharges the air flowing in from the first intake passage 22 and supplies it to the second intake passage 24 .

One end of the intercooler 26 is connected to the other end of the second intake passage 24 . The intercooler 26 is an air-cooled or water-cooled heat exchanger that cools the air flowing through the second intake passage 24 .

One end of the third intake passage 27 is connected to the other end of the intercooler 26 . An intake manifold 28 is connected to the other end of the third intake passage 27 . The intake manifold 28 is connected to the respective intake ports of the plurality of cylinders 12 of the engine body 10 .

The intake throttle valve 29 is provided in the third intake passage 27 . More specifically, the intake throttle valve 29 is provided between the junction of the intercooler 26 and the EGR passage 66 in the third intake passage 27 . The intake throttle valve 29 operates according to a control signal from the ECU 200 . The intake throttle valve 29 adjusts, for example, the flow rate of intake air flowing from the third intake passage 27 to the intake manifold 28 .

The exhaust manifold 50 is connected to the respective exhaust ports of the plurality of cylinders 12 of the engine body 10 . One end of the first exhaust passage 52 is connected to the exhaust manifold 50 . The other end of the first exhaust passage 52 is connected to the exhaust gas inlet of the turbine 36 of the supercharger 30 .

The supercharger 30 includes a compressor 32 and a turbine 36 . The compressor wheel 34 is accommodated in the casing of the compressor 32 , and the turbine wheel 38 is accommodated in the casing of the turbine 36 . The compressor wheel 34 and the turbine wheel 38 are connected by the connecting shaft 42 and rotate integrally. Thus, the compressor wheel 34 is driven in rotation by the exhaust energy of the exhaust gas supplied to the turbine wheel 38 .

One end of the second exhaust passage 54 is connected to the exhaust gas outlet of the turbine 36 . In the second exhaust passage 54, an exhaust treatment device 56 is provided. The exhaust gas treatment device 56 includes a NOx purification catalyst 56a, a DPF (Diesel Particulate Filter) 56b, and three exhaust gas temperature sensors 56c, 56d, and 56e.

The NOx purification catalyst 56a corresponds to the first catalyst in the present invention, and has a function of purifying nitrogen oxides (NOx) in the exhaust gas. As the NOx purification catalyst 56a, for example, an LNT catalyst (Lean Nitrogen oxides Trap catalyst) can be used. The NOx purification catalyst 56a has, for example, a function of storing NOx in the exhaust gas when the exhaust air-fuel ratio is low (when ambient oxygen is excessive), and when the exhaust air-fuel ratio is the theoretical air-fuel ratio or high (ambient oxygen is excessive) in the absence of oxygen) releases NOx. When the exhaust air-fuel ratio is the theoretical air-fuel ratio or higher, the NOx released from the NOx purification catalyst 56a reduces and purifies HC (hydrocarbon) and CO (carbon monoxide) in the exhaust as reducing agents. In addition, the NOx purification catalyst 56a also has a function of oxidizing and purifying HC and CO in the exhaust gas when the exhaust air-fuel ratio is low. As the NOx purification catalyst 56a, for example, a selective reduction type NOx catalyst (SCR (Selective Catalytic Reduction) catalyst) can also be used.

The DPF 56b is provided on the downstream side of the exhaust gas flow passage (exhaust passage) than the NOx purification catalyst 56a. The DPF 56b captures particulate matter (hereinafter, also referred to as "PM (Particulate Matter)") contained in the exhaust gas flowing through it. The DPF 56b is formed of, for example, ceramics and/or stainless steel.

The first exhaust gas temperature sensor 56c is provided on the upstream side of the exhaust gas flow path rather than the NOx purification catalyst 56a. The first exhaust temperature sensor 56c detects the temperature T1 of the exhaust gas flowing into the exhaust treatment device 56 . The first exhaust gas temperature sensor 56c transmits a signal indicating the detected exhaust gas temperature T1 to the ECU 200 .

The second exhaust gas temperature sensor 56d is provided between the NOx purification catalyst 56a and the DPF 56b. The second exhaust gas temperature sensor 56d detects the temperature T2 of the exhaust gas flowing out from the NOx purification catalyst 56a. The second exhaust gas temperature sensor 56d transmits a signal indicating the detected exhaust gas temperature T2 to the ECU 200 .

The third exhaust gas temperature sensor 56e is provided on the downstream side of the exhaust gas flow path rather than the DPF 56b. The third exhaust gas temperature sensor 56e detects the temperature T3 of the exhaust gas flowing out from the DPF 56b. The third exhaust gas temperature sensor 56e transmits a signal indicating the detected exhaust gas temperature T3 to the ECU 200 .

One end of the third exhaust passage 58 is connected to the rear end of the exhaust treatment device 56 . A muffler or the like is connected to the other end of the third exhaust passage 58 . An additional exhaust gas treatment device may be connected to the other end of the third exhaust passage 58 to remove specific components from exhaust gas such as a catalyst.

The EGR device 60 connects the third intake passage 27 to the exhaust manifold 50 . The EGR device 60 includes an EGR valve 62 , an EGR cooler 64 , and an EGR passage 66 . The EGR passage 66 connects the third intake passage 27 and the exhaust manifold 50 . The EGR valve 62 and the EGR cooler 64 are provided in the middle of the EGR passage 66 .

The EGR valve 62 adjusts the exhaust gas returned from the exhaust manifold 50 to the intake manifold 28 via the EGR passage 66 according to the control signal from the ECU 200 (hereinafter, the exhaust gas returned to the intake manifold 28 is also referred to as "EGR" Gas") flow rate.

The EGR cooler 64 is, for example, a water-cooled or air-cooled heat exchanger for cooling the EGR gas flowing through the EGR passage 66 . By returning the exhaust gas in the exhaust manifold 50 to the intake side as EGR gas through the EGR device 60, the combustion temperature in the cylinder is lowered and the amount of NOx generated is reduced.

Here, the NOx purification catalyst 56a has a characteristic that the purification performance of the exhaust gas improves as the temperature thereof rises. Therefore, in order for the NOx purification catalyst 56a to perform this function (the function of purifying NOx in the exhaust gas), the NOx purification catalyst 56a must be warmed up to a predetermined temperature (for example, the second temperature Tth2 described below) or higher and activation. Therefore, for example, when the NOx purification catalyst 56a is not activated such as when the engine 1 is started, there is a possibility that unpurified exhaust gas is discharged to the outside of the vehicle before the warm-up of the NOx purification catalyst 56a is completed.

Therefore, in Embodiment 1, when there is a request to start the engine 1, the ECU 200 executes the warm-up control. Hereinafter, the warm-up control and the configuration for executing the warm-up control will be specifically described.

In Embodiment 1, the bypass passage 70 is provided to bypass the exhaust gas flowing out of the exhaust manifold 50 upstream of the turbine 36 to the downstream of the turbine 36 . That is, the bypass passage 70 allows the exhaust gas flowing out of the exhaust manifold 50 to flow to the exhaust gas treatment device 56 without passing through the turbine 36 . One end of the bypass passage 70 is connected to the first exhaust passage 52 . The other end of the bypass passage 70 is connected to the second exhaust passage 54 on the upstream side of the exhaust gas flow passage from the exhaust treatment device 56 .

A switching valve 72 for switching the exhaust flow path is provided at the junction of the bypass passage 70 and the second exhaust passage 54 . The switching valve 72 is configured to be able to operate between a first state in which the exhaust gas flowing out of the exhaust manifold 50 is bypassed to the bypass passage 70 and a second state in which the exhaust gas flowing out from the exhaust manifold 50 is not bypassed to the bypass passage 70 . switch between states. That is, when the switching valve 72 is in the first state, the exhaust gas flowing out of the exhaust manifold 50 flows to the exhaust gas treatment device 56 through the bypass passage 70 . When the switching valve 72 is in the second state, the exhaust gas flowing out of the exhaust manifold 50 flows to the exhaust gas treatment device 56 via the turbine 36 . The switching valve 72 is switched between the first state and the second state in accordance with a control signal from the ECU 200 .

In the bypass passage 70, an electrically heated catalyst (hereinafter also referred to as "EHC (Electrically Heated Catalyst)") 75 is provided. EHC 75 includes ternary catalytic converter 76 and heater 77 . A three-way catalytic converter is a catalyst that purifies nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons (HC) contained in exhaust gas. A ternary catalytic converter reduces NOx to nitrogen and oxygen in the presence of reducing gases ( _H2 , CO or hydrocarbons). In addition, the ternary catalytic converter oxidizes carbon monoxide to carbon dioxide in the presence of an oxidizing gas. Also, the ternary catalytic converter oxidizes unburned hydrocarbons (HC) into carbon dioxide and water in the presence of an oxidizing gas. In order to efficiently oxidize or reduce the ternary catalytic converter, it is preferable that the fuel is completely burned in the engine body 10 and the combustion is carried out at a stoichiometry air/fuel ratio with no residual oxygen. (stoichiometric combustion). In addition, the thermal capacity of the three-way catalytic converter 76 is configured to be smaller than the thermal capacity of the NOx purification catalyst 56a of the exhaust gas treatment device 56 . That is, the three-way catalytic converter 76 is constituted so as to be able to be activated with less heat than the NOx purification catalyst 56a. The three-way catalytic converter 76 corresponds to the second catalytic converter in the present invention.

The heater 77 is configured to be able to raise the temperature of the ternary catalytic converter 76 . The heater 77 corresponds to the temperature raising means in the present invention. The heater 77 is, for example, an electric heater provided in contact with the ternary catalytic converter 76 . In Embodiment 1, the heater 77 is provided on the upstream side of the exhaust gas flow path rather than the ternary catalytic converter 76 . However, the location where the heater 77 is provided is not limited to the upstream side of the exhaust gas flow path relative to the ternary catalytic converter 76 , and may be provided, for example, on the downstream side of the exhaust gas flow path relative to the ternary catalytic converter 76 . . In addition, the heater 77 may be provided so as to cover the three-way catalytic converter 76, for example.

The ECU 200 executes the warm-up control when receiving a start request of the engine 1 . In the warm-up control, the ECU 200 operates the heater 77 to warm up (raise the temperature) the ternary catalytic converter 76 before starting the engine 1 (engine body 10 ). For example, the ECU 200 operates the heater 77 with a predetermined output, and determines that the three-way catalytic converter 76 is activated when the operation time of the heater 77 has passed a predetermined first predetermined time. The first predetermined time is, for example, a time during which the temperature of the ternary catalytic converter 76 can be made equal to or higher than the first temperature Tth1 by the operation of the heater 77 at the above-mentioned predetermined output. The first temperature Tth1 is the temperature at which the ternary catalytic converter 76 is activated. That is, the first predetermined time is a time during which the heat required for activating the three-way catalytic converter 76 can be supplied to the three-way catalytic converter 76 by the operation of the heater 77 with the above-mentioned predetermined output. The first predetermined time may be determined based on the specifications of the ternary catalytic converter 76, or may be determined based on the results of experiments, simulations, or the like. Furthermore, a temperature sensor capable of detecting the temperature of the three-way catalytic converter 76 may be further provided, and when the temperature of the three-way catalytic converter 76 is equal to or higher than the first temperature Tth1, the ECU 200 can determine that the temperature is a three-way catalytic converter. The catalytic converter 76 is activated.

Furthermore, before starting the engine 1 , the ECU 200 sets the switching valve 72 to the first state, and causes the exhaust gas to flow through the bypass passage 70 . The timing for bringing the switching valve 72 to the first state can be appropriately set as long as it is before the engine 1 is started.

After the warm-up of the three-way catalytic converter 76 is completed, the ECU 200 starts the engine 1 and causes the engine 1 to perform the first operation. The first operation means operating the engine 1 at a stoichiometric air-fuel ratio and a low rotational speed. The low rotational speed refers to a rotational speed lower than the engine rotational speed in the second operation described below. The rotational speed of the engine during the first operation is determined by the relationship with the flow rate of the exhaust gas that can be properly purified by the ternary catalytic converter 76 . Since the ECU 200 operates the engine 1 at the theoretical air-fuel ratio, it is possible to efficiently purify the exhaust gas by the ternary catalytic converter 76 . Furthermore, since the ECU 200 operates the engine 1 at a low rotational speed, the exhaust gas can be properly purified by restricting the flow rate of the exhaust gas to a flow rate that can be properly purified by the ternary catalytic converter 76 . Furthermore, the operation at a low rotational speed corresponds to an example of the "low-speed operation" of the present invention.

The exhaust gas after being purified by the three-way catalytic converter 76 flows into the exhaust gas treatment device 56 . Using this exhaust gas, the NOx purification catalyst 56a of the exhaust gas treatment device 56 is warmed up (raised up). The exhaust gas flowing into the NOx purification catalyst 56a is purified by the three-way catalytic converter 76 as described above. Therefore, discharge of unpurified exhaust gas from the exhaust gas treatment device 56 can also be suppressed until the NOx purification catalyst 56a is activated.

For example, the ECU 200 monitors the temperature T2 of the second exhaust gas temperature sensor 56d, and determines that the NOx purification catalyst 56a is activated when the temperature T2 becomes equal to or higher than the second temperature Tth2. When it is determined that the NOx purification catalyst 56 a is activated, the ECU 200 sets the switching valve 72 to the second state, and flows the exhaust gas to the turbine 36 .

The ECU 200 switches the engine 1 from the first operation to the second operation. The second operation refers to setting the operating point of the engine 1 to a high thermal efficiency point, and operating the engine 1 at the operating point. The so-called high thermal efficiency point, for example, refers to the operating point with the highest thermal efficiency on the operating line of the engine 1 . Since the engine 1 of the first embodiment is an engine for power generation, the operating point of the engine 1 can be set to a high thermal efficiency point regardless of the running state of the vehicle 300 . Furthermore, in the second operation, the operation is basically performed in a state where the air-fuel ratio is lower than the theoretical air-fuel ratio. After the NOx purification catalyst 56a has been activated, the engine 1 can be efficiently driven by causing the exhaust gas to flow through the turbine 36 to perform the second operation of the engine 1 . Since the NOx purification catalyst 56a is activated even when the engine 1 is operated in the second operation, the exhaust gas can be appropriately purified. By causing the engine 1 to perform the second operation, the fuel consumption required for charging the battery 7 can be suppressed. In addition, the second operation corresponds to an example of the "normal operation" of the present invention.

Furthermore, the "exhaust gas treatment system" of the first embodiment includes an exhaust passage (the first exhaust passage 52, the second exhaust passage 54), the bypass passage 70, the switching valve 72, the EHC 75, the exhaust gas treatment device 56, and ECU200.

<Process executed by ECU during warm-up control> FIG. 3 is a flowchart showing the sequence of processing executed by ECU 200 in the warm-up control. The steps shown in the flowchart are executed after being called by a main routine (not shown) when the engine 1 is stopped. The steps of the flowcharts shown in FIG. 3 and the following FIG. 6 will be described by using software processing of ECU 200 , but a part or all of them may be implemented by hardware (electrical circuit) built in ECU 200 . In addition, below, a step is abbreviated as "S".

When the engine 1 is stopped, the ECU 200 starts to execute this flowchart. Furthermore, when the vehicle 300 is started, the ECU 200 also starts to execute the flowchart.

ECU 200 determines whether or not there is a request to start engine 1 (S1). When it is determined that there is no start request of the engine 1 (NO in S1 ), the ECU 200 executes the process of S1 again to monitor whether there is a start request of the engine 1 .

When it is determined that there is a request to start the engine 1 (YES in S1 ), the ECU 200 starts the warm-up control. In the warm-up control, the ECU 200 first operates the heater 77 to warm up the ternary catalytic converter 76 of the EHC 75 (S3). Next, the ECU 200 sets the switching valve 72 to the first state (S5). Thereby, when the engine 1 is started, the exhaust gas flows through the bypass passage 70 . Furthermore, the process of S5 only needs to be executed before the engine 1 is started, for example, it may be executed before the process of S3 or after the process of S7 described below makes a positive determination.

ECU 200 determines whether ternary catalytic converter 76 is activated (S7). Specifically, the ECU 200 determines whether or not the first predetermined time has elapsed after the heater 77 was operated. When the first predetermined time has not elapsed after the heater 77 is operated (NO in S7), the ECU 200 waits for the elapse of the first predetermined time.

When the first predetermined time elapses after the heater 77 is operated (YES in S7 ), the ECU 200 determines that the three-way catalytic converter 76 is activated. Furthermore, in this case, the ECU 200 may stop the heater 77 . When it is determined that the three-way catalytic converter 76 is activated, the ECU 200 starts the engine 1 and causes the engine 1 to perform the first operation ( S9 ). The NOx purification catalyst 56a of the exhaust gas treatment device 56 is warmed up by the exhaust gas generated by causing the engine 1 to perform the first operation.

The ECU 200 determines whether or not the NOx purification catalyst 56a of the exhaust treatment device 56 has been activated (S11). Specifically, the ECU 200 monitors the temperature T2 detected by the second exhaust gas temperature sensor 56d, and determines that the NOx purification catalyst 56a is activated when the temperature T2 is equal to or higher than the second temperature Tth2.

When the temperature T2 is lower than the second temperature Tth2 (No in S11 ), the ECU 200 waits for the temperature T2 to become equal to or higher than the second temperature Tth2 (No in S11 ). When the temperature T2 is equal to or higher than the second temperature Tth2, the ECU 200 determines that the NOx purification catalyst 56a is activated (YES in S11), and sets the switching valve 72 to the second state (S13). Thereby, the exhaust gas flows through the turbine 36 .

ECU 200 switches the engine 1 from the first operation to the second operation (S15). Thereby, the exhaust gas can be appropriately purified by the exhaust gas treatment device 56, and the engine 1 can be operated efficiently.

As described above, in the vehicle 300 provided with the exhaust gas treatment system of the first embodiment, the ECU 200 operates the heater 77 of the EHC 75 before starting the engine 1 when there is a request to start the engine 1 (request for power generation), so that the The ternary catalytic converter 76 is activated. Then, after activation of the three-way catalytic converter 76 , the ECU 200 sets the switching valve 72 to the first state, causes the engine 1 to perform the first operation (theoretical air-fuel ratio and low rotational speed), and allows the exhaust gas to flow in through the bypass passage 70 . to the exhaust treatment device 56 . The NOx purification catalyst 56a of the exhaust gas treatment device 56 is warmed up by this exhaust gas. Since the exhaust gas flowing into the exhaust treatment device 56 is purified by the three-way catalytic converter 76, it is possible to suppress the discharge of unpurified exhaust gas to the outside of the vehicle even before the NOx purification catalyst 56a is activated. Furthermore, by causing the engine 1 to perform the first operation, the ECU 200 can limit the flow rate of the exhaust gas to a flow rate that can be properly purified by the ternary catalytic converter 76 and can efficiently Exhaust purification.

In addition, in general, a three-way catalytic converter is less expensive than a NOx purification catalyst. In the first operation, the ternary catalytic converter 76 can be used for the EHC 75 by operating the engine 1 in a state where the air-fuel ratio is the theoretical air-fuel ratio. Thereby, the cost of EHC75 can be suppressed.

When activating the NOx purification catalyst 56a, the ECU 200 sets the switching valve 72 to the second state, and causes the engine 1 to perform the second operation. Thereby, the engine 1 can be operated at a high thermal efficiency point. Therefore, the fuel consumption required for charging the battery 7 can be suppressed. In addition, the exhaust gas can be appropriately purified by the exhaust gas treatment device 56 .

Furthermore, in Embodiment 1, the bypass passage 70 is provided, and the EHC 75 is provided in the bypass passage 70 . For example, if the EHC 75 is provided in the first exhaust passage 52 instead of the bypass passage 70, during the second operation, the EHC 75 restricts the flow of exhaust gas to generate a pressure drop, which may cause a supercharging delay. In the first embodiment, by providing the bypass passage 70, it is possible to suppress the occurrence of a supercharging delay during the second operation.

In addition, by bypassing the turbine 36 during the warm-up of the NOx purification catalyst 56a, for example, the rotation of the turbine 36 can prevent the thermal energy of the exhaust gas from being taken away. Thereby, the NOx purification catalyst 56a can be activated early.

It is also considered that EHC is used for the exhaust treatment device 56, and the NOx purification catalyst 56a of the exhaust treatment device 56 is warmed up and activated by a heater. However, since the NOx purification catalyst 56a is configured to be able to properly purify the exhaust gas during the second operation, its heat capacity is relatively large. Therefore, the power consumption required to activate the NOx purification catalyst 56a is relatively large. That is, in order to activate the NOx purification catalyst 56a, a large amount of electric power is extracted from the battery 7, and the distance that the vehicle 300 can travel may be shortened accordingly. In Embodiment 1, since the power consumption of the heater 77 is sufficient to activate the three-way catalytic converter 76 having a smaller thermal capacity than the NOx purification catalyst 56a, it is different from the power consumption of the NOx purification catalyst 56a by the heater. Compared with the case of activation, power consumption can be suppressed. Thereby, the distance which the vehicle 300 can travel can be suppressed from being shortened.

[Variation 1] In Embodiment 1, the bypass passage 70 is provided, and the EHC 75 is provided in the bypass passage 70 . However, from the viewpoint of purifying exhaust gas, the bypass passage 70 can also be omitted. Although the above-described pressure drop may occur, for example, the bypass passage 70 may be omitted, and the EHC 75 may be provided in the first exhaust passage 52 or the second exhaust passage 54 . Furthermore, when the EHC 75 is provided in the second exhaust passage 54 , the EHC 75 is provided at a position on the upstream side of the exhaust flow passage relative to the exhaust treatment device 56 .

FIG. 4 is a diagram showing a schematic configuration of the engine 1 including the exhaust gas treatment system provided with the EHC 75 in the first exhaust passage 52 . FIG. 5 is a diagram showing a schematic configuration of the engine 1 including the exhaust gas treatment system provided with the EHC 75 in the second exhaust passage 54 . In any configuration, the bypass passage 70 and the switching valve 72 are omitted in the configuration of the engine 1 shown in FIG. 2 of the first embodiment.

In any of the above configurations, when there is a request to start the engine 1, the ECU 200 executes the warm-up control. In the warm-up control in Modification 1, the ECU 200 drives the heater 77 of the EHC 75 to activate the three-way catalytic converter 76 before starting the engine 1 . After activating the three-way catalytic converter 76, the ECU 200 starts the engine 1 and operates the engine 1 in the first operation mode. The ECU 200 operates the engine 1 in the first operation mode, and activates the NOx purification catalyst 56a of the exhaust gas treatment device 56 using the exhaust gas. Since the exhaust gas when the NOx purification catalyst 56a is activated is purified by the three-way catalytic converter 76, it is possible to suppress the unpurified exhaust gas from being released from the exhaust treatment device 56 before the NOx purification catalyst 56a is activated. discharge.

When activating the NOx purification catalyst 56a, the ECU 200 switches from the first operation to the second operation to operate the engine 1 . Thereby, the engine 1 can be operated at a high thermal efficiency point.

FIG. 6 is a flowchart showing the sequence of processing executed by the ECU 200 in the warm-up control in the modification 1. FIG. The flowchart shown in FIG. 6 is a diagram in which the processes of S5 and S13 are deleted from the flowchart of FIG. 3 . As for other processing, since it is the same as the processing in the flowchart of FIG. 3 , the same step numbers are marked, and the description thereof will not be repeated.

As described above, also in the exhaust gas treatment system of Modification 1, it is possible to suppress the discharge of unpurified exhaust gas to the outside of the vehicle.

[Variation 2] In Embodiment 1 and Modification 1, an example in which the engine 1 is a diesel engine has been described. However, the engine 1 is not limited to a diesel engine, and may be a gasoline engine, for example.

When the engine 1 is a gasoline engine, the ECU 200 may also operate the engine 1 in a state where the air-fuel ratio is the theoretical air-fuel ratio during the second operation. If the engine 1 is operated with the air-fuel ratio being the theoretical air-fuel ratio in both the first operation and the second operation, even if the NOx purification catalyst 56a of the exhaust treatment device 56 is replaced with a three-way catalyst The converter can also efficiently purify the exhaust gas. As described above, in general, three-way catalytic converters are less expensive than NOx purification catalysts. Therefore, when the engine 1 is a gasoline engine, the parts cost of the exhaust gas treatment system can be suppressed.

In addition, Variation 2 can also be combined with Embodiment 2 and Variation 3 described below.

[Embodiment 2] In Embodiment 1 and Modifications 1 and 2, the warm-up control using EHC75 has been described. In Embodiment 2, the warm-up control using EH (Electric Heater, electric heater) is demonstrated.

1 again, vehicle 300A according to Embodiment 2 includes engine 1A, first motor generator 2, second motor generator 3, PCU 4, transmission gear 5, drive shaft 6, battery 7, monitoring unit 9, and ECU 200A. Furthermore, vehicle 300 includes DC/DC converter 110 , auxiliary battery 120 , and low-voltage auxiliary device 130 . That is, in the vehicle 300A of the second embodiment, the engine 1 is replaced by the engine 1A, and the ECU 200 is replaced by the ECU 200A, as compared with the vehicle 300 of the first embodiment. The other components of the vehicle 300A are the same as those of the vehicle 300, and therefore will not be described again. The engine 1A and the ECU 200A will be specifically described with reference to FIG. 7 .

FIG. 7 is a diagram showing a schematic configuration of an engine 1A including the exhaust gas treatment system in Embodiment 2. As shown in FIG. A ternary catalytic converter 76 and an EH 79 are provided in the bypass passage 70 of the exhaust gas treatment system of the engine 1A of the second embodiment. EH79 is equivalent to the heating device in the present invention. The EH 79 is provided on the upstream side of the exhaust gas flow path relative to the ternary catalytic converter 76 . The EH 79 operates according to the control signal from the ECU 200A, and increases the temperature of the exhaust gas flowing in the bypass passage 70 . In addition, since the structure other than EH79 and ECU200A is the same as that of the engine 1 of Embodiment 1, description is not repeated. In addition, the heat capacity of the three-way catalytic converter 76 is configured to be smaller than the heat capacity of the NOx purification catalyst 56a of the exhaust gas treatment device 56, as in the first embodiment.

The ECU 200A executes the warm-up control when receiving the start request of the engine 1A. In the warm-up control, the ECU 200A operates the EH 79 before starting the engine 1A. The ECU 200A sets the switching valve 72 to the first state. Then, the ECU 200A uses the first motor generator 2 to perform motor driving of the engine 1A. Furthermore, the ECU 200A prohibits fuel injection into the engine 1A (engine body 10 ) when the motor drive is executed. The exhaust gas is discharged from the engine body 10 by the motor drive. The exhaust gas is heated up by the EH 79, and the ternary catalytic converter 76 is warmed up by the heated exhaust gas.

NOx etc. are not contained in the exhaust gas discharged|emitted from the engine main body 10 by a motor drive. Therefore, by using this exhaust gas to warm up the three-way catalytic converter 76, it is possible to suppress the discharge of exhaust gas including NOx and the like to the outside of the vehicle, and to activate the three-way catalytic converter 76.

During the execution of the motor drive, the ECU 200A monitors whether the three-way catalytic converter 76 is activated. Specifically, ECU 200A operates EH 79 with a predetermined output, for example, and a predetermined time elapses after the start of motor driving (ie, the time after exhaust gas heated up by EH 79 starts to flow into ternary catalytic converter 76 ). In the case of the second predetermined time, it is determined that the ternary catalytic converter 76 is activated. The second predetermined time is, for example, a time during which the temperature of the ternary catalytic converter 76 can be made equal to or higher than the first temperature Tth1 when the EH 79 is operated with the above-mentioned predetermined output and the motor is driven. The second predetermined time may be determined based on the specifications of the ternary catalytic converter 76, or may be determined based on the results of experiments or simulations. Furthermore, a temperature sensor capable of detecting the temperature of the three-way catalytic converter 76 may be further provided, and the ECU 200A determines that the three-way catalytic converter is a three-way catalytic converter when the temperature of the three-way catalytic converter 76 is equal to or higher than the first temperature Tth1 Converter 76 is activated. When it is determined that the three-way catalytic converter 76 is activated, the ECU 200A starts the engine 1A and causes the engine 1A to perform the first operation.

The ternary catalytic converter 76 is properly purified after the exhaust gas caused by the first operation of the engine 1A is activated. Then, the exhaust gas purified by the three-way catalytic converter 76 flows into the exhaust gas treatment device 56 . Using this exhaust gas, the NOx purification catalyst 56a of the exhaust gas treatment device 56 is warmed up (raised up). The exhaust gas flowing into the NOx purification catalyst 56a is purified by the three-way catalytic converter 76 as described above. Therefore, discharge of unpurified exhaust gas from the exhaust gas treatment device 56 can also be suppressed until the NOx purification catalyst 56a is activated.

For example, the ECU 200A monitors the temperature T2 of the second exhaust gas temperature sensor 56d, and determines that the NOx purification catalyst 56a is activated when the temperature T2 becomes equal to or higher than the second temperature Tth2. When it is determined that the NOx purification catalyst 56a is activated, the ECU 200A sets the switching valve 72 to the second state, and causes the exhaust gas to flow to the turbine 36 .

Furthermore, ECU 200A switches the engine 1A from the first operation to the second operation. The exhaust gas generated by the second operation of the engine 1A is appropriately purified by the NOx purification catalyst 56a. By causing the engine 1A to perform the second operation, the engine 1A can be operated at an operating point with good thermal efficiency. Therefore, the fuel consumption required for charging the battery 7 can be suppressed.

As described above, when the NOx purification catalyst 56a is warmed up, the exhaust gas is made to bypass the turbine 36 and circulate. Thereby, for example, it is possible to prevent the thermal energy of the exhaust gas from being taken away by the rotation of the turbine 36 , so that the NOx purification catalyst 56a can be activated earlier than the case where the turbine 36 is not bypassed. That is, since the time required to drive the electric motor can be shortened, the power consumption of the battery 7 can be suppressed, and the reduction in the distance that the vehicle 300A can travel can be suppressed.

<Process executed by ECU during warm-up control> FIG. 8 is a flowchart showing the procedure of the processing executed by the ECU 200A in the warm-up control in the second embodiment. The steps shown in the flowchart are executed after being called by a main routine (not shown) when the engine 1 is stopped. The case where each step of the flowchart shown in FIG. 8 and the following FIG. 11 is realized by software processing of ECU 200A will be described, but a part or all of it may be realized by hardware (electrical circuit) produced in ECU 200A. .

When the engine 1A is stopped, the ECU 200A starts to execute this flowchart. Furthermore, when the vehicle 300A is started, the ECU 200A also starts to execute the flowchart.

The ECU 200A determines whether or not there is a request to start the engine 1A (S51). When it is determined that there is no start request of the engine 1A (NO in S51 ), the ECU 200A executes the process of S51 again, and monitors whether there is a start request of the engine 1A.

When it is determined that there is a request to start the engine 1A (YES in S51 ), the ECU 200A starts the warm-up control. In the warm-up control, the ECU 200A first sets the switching valve 72 to the first state ( S53 ). Then, ECU 200A operates EH 79 (S55). In addition, the execution order of the processing of S53, S55, and the following S57 may be suitably changed.

Then, the ECU 200A executes the motor drive of the engine 1A using the first motor generator 2 ( S57 ). In this case, ECU 200A prohibits fuel injection into engine 1A. The exhaust gas discharged from the engine body 10 driven by the motor flows in the bypass passage 70 and is heated up by the EH 79 . Then, the heated exhaust gas flows into the ternary catalytic converter 76 , thereby warming up the ternary catalytic converter 76 .

ECU 200A determines whether ternary catalytic converter 76 has been activated (S58). Specifically, ECU 200A operates EH 79 with a predetermined output, and determines whether or not a second predetermined time has elapsed after the start of motor driving. When the ECU 200A operates the EH 79 and the second predetermined time has not elapsed since the start of the motor drive (NO in S58 ), the ECU 200A waits for the elapse of the second predetermined time.

When the EH 79 is operated and the second predetermined time has elapsed after the start of the motor drive (YES in S58 ), the ECU 200A determines that the three-way catalytic converter 76 is activated. When it is determined that the three-way catalytic converter 76 is activated, the ECU 200A starts the engine 1A and causes the engine 1A to perform the first operation ( S59 ). The exhaust gas caused by the first operation of the engine 1A is purified by the ternary catalytic converter 76 and flows into the exhaust gas treatment device 56 . Then, using this exhaust gas, the NOx purification catalyst 56a of the exhaust gas treatment device 56 is warmed up.

The ECU 200A determines whether or not the NOx purification catalyst 56a of the exhaust gas treatment device 56 has been activated (S60). Specifically, the ECU 200A monitors the temperature T2 detected by the second exhaust temperature sensor 56d, and determines that the NOx purification catalyst 56a is activated when the temperature T2 is equal to or higher than the second temperature Tth2.

When the temperature T2 is lower than the second temperature Tth2 (NO in S60 ), the ECU 200A waits for the temperature T2 to become the second temperature Tth2 or higher. When the temperature T2 is equal to or higher than the second temperature Tth2, the ECU 200A determines that the NOx purification catalyst 56a is activated (YES in S60), and sets the switching valve 72 to the second state (S61). Then, the ECU 200A stops the EH 79 (S63), and switches the engine 1A from the first operation to the second operation (S65). Thereby, the exhaust gas can be appropriately purified by the exhaust gas treatment device 56, and the engine 1A can be operated efficiently.

As described above, in the vehicle 300A provided with the exhaust gas treatment system of the second embodiment, the ECU 200A sets the switching valve 72 to the first state when there is a request to start the engine 1A (request for power generation), and uses the first motor to generate power. The motor 2 performs motor drive for the engine 1A. Then, the ECU 200A raises the temperature of the exhaust gas discharged from the engine main body 10 by the electric motor drive by the EH 79 . Then, the ternary catalytic converter 76 is activated by the exhaust gas after the temperature rise. Since NOx and the like are not included in the exhaust gas discharged from the engine body 10 driven by the motor, the ternary catalytic converter 76 can be activated without discharging the exhaust gas including NOx and the like to the outside of the vehicle. Then, after the activation of the three-way catalytic converter 76 , the ECU 200A sets the switching valve 72 to the first state, starts the engine 1A to perform the first operation (theoretical air-fuel ratio and low rotational speed), and causes the exhaust gas to pass through the bypass passage 70 . The air flows into the exhaust treatment device 56 . Using this exhaust gas, the NOx purification catalyst 56a of the exhaust gas treatment device 56 is warmed up. Since the exhaust gas flowing into the exhaust treatment device 56 is purified by the three-way catalytic converter 76, the discharge of unpurified exhaust gas to the outside of the vehicle can also be suppressed until the NOx purification catalyst 56a is activated. In addition, by operating the engine 1A to perform the first operation, the ECU 200A can limit the flow rate of the exhaust gas to a flow rate that can be properly purified by the ternary catalytic converter 76, and can efficiently convert the exhaust gas by the ternary catalytic converter 76 Exhaust purification.

In addition, by bypassing the turbine 36 during the warm-up of the NOx purification catalyst 56a, for example, the rotation of the turbine 36 can prevent the thermal energy of the exhaust gas from being taken away. Thereby, the NOx purification catalyst 56a can be activated early.

When the NOx purification catalyst 56a is activated, the ECU 200A sets the switching valve 72 to the second state, and switches the engine 1A from the first operation to the second operation. During the second operation, by passing the exhaust gas through the turbine 36, the engine 1A can be operated at an operating point with good thermal efficiency. Thereby, the fuel consumption required for charging the battery 7 can be suppressed.

[Variation 3] In Embodiment 2, the bypass passage 70 is provided, and the EH 79 and the ternary catalytic converter 76 are provided in the bypass passage 70 . However, the EH 79 and the three-way catalytic converter 76 may be provided in the first exhaust passage 52 or the second exhaust passage 54 . Furthermore, when the EH 79 and the three-way catalytic converter 76 are disposed in the second exhaust passage 54 , the EH 79 and the three-way catalytic converter 76 are disposed upstream of the exhaust gas flow passage relative to the exhaust gas treatment device 56 . side position.

FIG. 9 is a diagram showing a schematic configuration of an engine 1A including an exhaust gas treatment system in which an EH 79 and a three-way catalytic converter 76 are provided in the first exhaust passage 52 . FIG. 10 is a diagram showing a schematic configuration of an engine 1A including an exhaust gas treatment system in which an EH 79 and a three-way catalytic converter 76 are provided in the second exhaust passage 54 . In any of the configurations, in the configuration of the engine 1A shown in FIG. 7 of the second embodiment, the bypass passage 70 and the switching valve 72 are omitted.

In any of the above configurations, when there is a request to start the engine 1A, the ECU 200A executes the warm-up control. In the warm-up control in the modified example 3, before starting the engine 1A, the ECU 200A operates the EH 79 and uses the first motor generator 2 to drive the engine 1A by motor. The exhaust gas discharged from the engine body 10 driven by the electric motor is heated up by the EH 79, and the ternary catalytic converter 76 is warmed up by the exhaust gas after the temperature rise. NOx etc. are not contained in the exhaust gas discharged|emitted from the engine main body 10 by a motor drive. Therefore, it is possible to activate the three-way catalytic converter 76 without discharging exhaust gas including NOx and the like to the outside of the vehicle.

When activating the three-way catalytic converter 76, the ECU 200A starts the engine 1A and operates the engine 1A in the first operation mode. Exhaust gas caused by the first operation of the engine 1A is appropriately purified by the activated ternary catalytic converter 76 . Then, the exhaust gas purified by the three-way catalytic converter 76 flows into the exhaust gas treatment device 56 . Using this exhaust gas, the NOx purification catalyst 56a of the exhaust gas treatment device 56 is warmed up (raised up). The exhaust gas flowing into the NOx purification catalyst 56a is purified by the three-way catalytic converter 76 as described above. Therefore, discharge of unpurified exhaust gas from the exhaust gas treatment device 56 can also be suppressed until the NOx purification catalyst 56a is activated.

For example, the ECU 200A monitors the temperature T2 of the second exhaust gas temperature sensor 56d, and determines that the NOx purification catalyst 56a is activated when the temperature T2 becomes equal to or higher than the second temperature Tth2. When it is determined that the NOx purification catalyst 56a is activated, the ECU 200A switches from the first operation to the second operation. Thereby, the engine 1 can be operated at a high thermal efficiency point. By causing the engine 1A to perform the second operation, the fuel consumption required for charging the battery 7 can be suppressed. The exhaust gas at this time is appropriately purified by the exhaust gas treatment device 56 .

FIG. 11 is a flowchart showing the sequence of processing executed by the ECU 200A in the warm-up control in the modification 3. As shown in FIG. The flowchart shown in FIG. 11 has the processing of S53 and S61 deleted from the flowchart of FIG. 8 . As for other processing, since it is the same as the processing in the flowchart of FIG. 8 , the same step numbers are marked, and the description will not be repeated.

As described above, also in the exhaust gas treatment system of Modification 3, it is possible to suppress the discharge of unpurified exhaust gas to the outside of the vehicle.

The embodiments disclosed this time are considered to be illustrative and non-restrictive in all respects. The scope of the present invention is shown by the scope of the patent application, not by the description of the above-described embodiments, and includes the meaning equivalent to the scope of the patent application and all changes within the scope.

1,1A: Engine 2: 1st motor generator 3: 2nd motor generator 4: PCU 4a, 4b: Inverter 4c: Converter 5: Transmission gear 6: Drive shaft 7: Battery 8: Single battery 9: Monitoring unit 10: Engine body 12: Cylinder 14: Common Track 16: Ejector 20: Air Cleaner 22: 1st intake passage 24: Second intake passage 26: Intercooler 27: 3rd intake passage 28: Intake manifold 29: Intake throttle valve 30: Supercharger 32: Compressor 34: Compressor Wheel 36: Turbine 38: Turbine Wheel 42: connecting shaft 50: Exhaust manifold 52: 1st exhaust passage 54: Second exhaust passage 56: Exhaust treatment device 56a: NOx purification catalyst 56c: 1st exhaust temperature sensor 56d: 2nd exhaust temperature sensor 56e: 3rd exhaust temperature sensor 58: 3rd exhaust passage 60: EGR device 62: EGR valve 64: EGR cooler 66: EGR pathway 70: Bypass 72: Switching valve 75: EHC 76: Ternary catalytic converter 77: Heater 79:EH 110: DC/DC Converter 120: Auxiliary battery 130: Low-voltage auxiliary equipment 200:ECU 210:CPU 220: memory 250: Battery ECU 300,300A: Vehicle

FIG. 1 is a diagram schematically showing the overall configuration of a vehicle according to the first embodiment. FIG. 2 is a diagram showing a schematic configuration of an engine including the exhaust gas treatment system in Embodiment 1. FIG. FIG. 3 is a flowchart showing the sequence of processing executed by the ECU in the warm-up control. FIG. 4 is a diagram showing a schematic configuration of an engine including an exhaust gas treatment system provided with an EHC in a first exhaust passage. 5 is a diagram showing a schematic configuration of an engine including an exhaust gas treatment system provided with EHC in a second exhaust passage. FIG. 6 is a flowchart showing the sequence of processing performed by the ECU in the warm-up control in the modification 1. FIG. FIG. 7 is a diagram showing a schematic configuration of an engine including the exhaust gas treatment system in Embodiment 2. FIG. 8 is a flowchart showing the sequence of processing executed by the ECU in the warm-up control in the second embodiment. 9 is a diagram showing a schematic configuration of an engine including an exhaust gas treatment system in which an EH and a three-way catalytic converter are provided in the first exhaust passage. 10 is a diagram showing a schematic configuration of an engine including an exhaust gas treatment system in which an EH and a three-way catalytic converter are provided in the second exhaust passage. 11 is a flowchart showing the sequence of processing performed by the ECU in the warm-up control in the modification 3. FIG.

Claims (7)

An exhaust gas treatment system for a series hybrid vehicle, the series hybrid vehicle includes an engine for power generation, and the exhaust gas treatment system includes: a first catalytic converter installed in the exhaust passage of the power generation engine; a second catalyst disposed upstream of the first catalyst in the exhaust passage; a temperature raising device configured to be able to raise the temperature of the second catalytic converter or the exhaust gas flowing into the second catalytic converter; and a control device that controls the above-mentioned power generation engine and the above-mentioned temperature rising device; and When there is a request to start the power generation engine, the control device operates the power generation engine in a normal operation mode after performing the warm-up control, In the above-mentioned warm-up control, the above-mentioned control device is before the engine for power generation is started, the temperature raising device is operated to activate the second catalyst, After activating the said 2nd catalyst, the said engine for electric power generation is started, and the said 1st catalyst is activated. The exhaust gas treatment system of a series hybrid vehicle as claimed in claim 1, wherein The above-mentioned first catalyst is configured to be able to purify the exhaust gas during the above-mentioned normal operation, The heat capacity of the second catalytic converter is smaller than that of the first catalytic converter, and is configured to purify the exhaust gas during a low-speed operation in which the engine for power generation is operated at a rotational speed lower than the normal operation, In the above-mentioned warm-up control, the above-mentioned control device is before the engine for power generation is started, the temperature raising device is operated to activate the second catalyst, After activating the second catalytic converter, the power generation engine is started, and the power generation engine is operated in the low-speed operation mode to activate the first catalytic converter, After activating the said 1st catalyst, the said engine for electric power generation is operated in the said normal operation|movement. The exhaust gas treatment system of a series hybrid vehicle as claimed in claim 2, wherein The above-mentioned second catalytic converter is a three-way catalytic converter, In the above-mentioned warm-up control, the above-mentioned control device is before the engine for power generation is started, the temperature raising device is operated to activate the second catalyst, After activating the second catalyst, the engine for power generation is started, the engine for power generation is operated at the low speed and the air-fuel ratio becomes the theoretical air-fuel ratio, and the first catalyst is activated, After activating the said 1st catalyst, the said engine for electric power generation is operated in the said normal operation|movement. The exhaust gas treatment system of a series hybrid vehicle as claimed in any one of claims 1 to 3, wherein The above-mentioned power generation engine includes a turbocharger, The first catalyst is provided in the exhaust passage downstream of the turbine of the turbocharger, The exhaust gas treatment system of the above-mentioned series hybrid vehicle further comprises: a bypass passage that branches from the exhaust passage upstream of the turbine, bypasses the turbine, and joins the exhaust passage upstream of the first catalyst; and a switching valve configured to be switchable between a first state in which the exhaust gas flows through the bypass passage and a second state in which the exhaust gas does not flow through the bypass passage; and The second catalyst and the temperature raising device are provided in the bypass passage, In the above-mentioned warm-up control, the above-mentioned control device is before the first catalyst is activated, the switching valve is set to the first state, When the said 1st catalyst is activated, the said switching valve is made into the said 2nd state. The exhaust gas treatment system of a series hybrid vehicle as claimed in any one of claims 1 to 3, wherein The temperature-raising device is an electric heater provided in contact with the second catalytic converter, In the above-mentioned warm-up control, the above-mentioned control device is Before starting the engine for power generation, the electric heater is operated to heat up and activate the second catalyst, After activating the said 2nd catalyst, the said engine for electric power generation is started, and the said 1st catalyst is activated. The exhaust gas treatment system of a series hybrid vehicle as claimed in any one of claims 1 to 3, further comprising a rotating electrical machine connected to the crankshaft of the above-mentioned power generating engine; and The temperature raising device is installed in the exhaust passage upstream of the second catalytic converter, and is an electric heater that raises the temperature of the exhaust gas, In the above-mentioned warm-up control, the above-mentioned control device is Before starting the engine for power generation, the engine for power generation is driven by a motor using the rotating electrical machine, operating the electric heater to raise the temperature of the exhaust gas to activate the second catalyst, After activating the said 2nd catalyst, the said engine for electric power generation is started, and the said 1st catalyst is activated. The exhaust gas treatment system of a series hybrid vehicle as claimed in any one of claims 1 to 3, wherein During the normal operation, the control device operates the power generation engine at a maximum thermal efficiency point at which the thermal efficiency of the power generation engine is maximized.

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