JP7342816B2 - Series hybrid vehicle exhaust treatment system - Google Patents

Description

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

Japanese Unexamined Patent Publication No. 2018-178892 (Patent Document 1) discloses a catalyst warm-up device disposed in an exhaust passage of an internal combustion engine having a supercharger. This catalyst warm-up device has an exhaust bypass passage that bypasses the turbine of the supercharger and is connected to the exhaust passage upstream of the catalyst that purifies exhaust gas. The exhaust bypass valve that opens and closes the exhaust bypass passage is provided with a heat generating portion at a location where the exhaust gas flowing through the exhaust bypass passage comes into contact with the exhaust bypass valve. The catalyst warm-up device warms up the catalyst early by causing exhaust gas to flow through the exhaust bypass passage and heating the exhaust gas in a heat generating section.

Japanese Patent Application Publication No. 2018-178892

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

The present disclosure has been made to solve the above problems, and its purpose is to suppress the emission of unpurified exhaust gas.

(1) The exhaust treatment system according to this disclosure is an exhaust treatment system for a series hybrid vehicle equipped with a power generation engine. The exhaust treatment system for a series hybrid vehicle includes a first catalyst provided in the exhaust passage of a power generation engine, a second catalyst provided upstream of the first catalyst in the exhaust passage, and a second catalyst or a second catalyst provided in the exhaust passage. A temperature raising device configured to be able to raise the temperature of exhaust gas flowing into the catalyst, and a control device controlling the power generation engine and the temperature raising device. When there is a request to start the power generation engine, the control device executes warm-up control and then operates the power generation engine in normal operation. 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 starts the power generation engine after activating the second catalyst. , activating the first catalyst.

According to the above configuration, the exhaust treatment system includes the first catalyst, the second catalyst, and a 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 to start the power generation engine (that is, a power generation request), the control device operates the temperature raising device to activate the second catalyst before starting the power generation engine. After activating the second catalyst, the control device starts the power generation engine and activates the first catalyst using the exhaust gas. The exhaust gas at this time passes through the second catalyst and is purified, then flows into the first catalyst and activates the first catalyst. Therefore, even before the first catalyst is activated, unpurified exhaust gas can be prevented from being discharged to the outside of the vehicle.

(2) In one embodiment, the first catalyst is configured to be able to purify exhaust gas during normal operation. Further, the second catalyst has a smaller heat capacity than the first catalyst, and is configured to be able 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 temperature raising device to activate the second catalyst before starting the power generation engine, and starts the power generation engine after activating the second catalyst. , the power generation engine is operated at low speed to activate the first catalyst, and after activating the first catalyst, the power generation engine is operated at normal operation.

It is sufficient that the temperature raising device has the ability to raise the temperature of the second catalyst. According to the above configuration, the second catalyst has a smaller heat capacity than the first catalyst, and is configured to be able to purify exhaust gas during low-speed operation. Therefore, it is possible to use a temperature raising device that is lower in performance and smaller than, for example, a case where a temperature raising device for raising the temperature of the first catalyst is provided, and cost reduction and space saving can be achieved.

Furthermore, since the heat capacity of the second catalyst is smaller than that of the first catalyst, the power consumption required for activating the catalyst can be reduced compared to when activating the first catalyst using a temperature raising device. I can do it.

(3) In some embodiments, the second catalyst is a three-way catalyst. 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 starts the power generation engine after activating the second catalyst. , the power generation engine is operated at low speed and the air-fuel ratio becomes the stoichiometric air-fuel ratio to activate the first catalyst, and after activating the first catalyst, the power generation engine is operated in normal operation. Let them drive.

According to the above configuration, a three-way catalyst is used as the second catalyst, and during warm-up control, the power generation engine is operated so that the air-fuel ratio becomes the stoichiometric air-fuel ratio. In general, three-way catalysts are cheaper than Nox purification catalysts, so by using a three-way catalyst as the second catalyst, the cost of parts for the exhaust treatment system can be reduced compared to when using a Nox purification catalyst. I can do it. Further, in the warm-up control, the control device operates the power generation engine so that the air-fuel ratio becomes the stoichiometric air-fuel ratio, so that the three-way catalyst can efficiently purify the exhaust gas.

(4) In some embodiments, the power generation engine has a turbocharger. The first catalyst is provided downstream of the turbine of the turbocharger in the exhaust passage. The exhaust treatment system of a series hybrid vehicle branches from an exhaust passage upstream of a turbine, bypasses the turbine and joins the exhaust passage upstream of a first catalyst, and flows exhaust through the bypass passage. The vehicle further includes a switching valve configured to be able to switch between the first state and a second state in which exhaust gas flows without passing through the bypass passage. The second catalyst and temperature raising device are provided in the bypass passage. In the warm-up control, the control device puts the switching valve in the first state until the first catalyst is activated, and puts the switching valve in the second state when the first catalyst is activated. .

If a second catalyst is provided in the exhaust passage upstream of the turbine without providing a bypass passage, for example, during normal operation, the second catalyst restricts the exhaust flow, causing pressure loss and causing a supercharging delay. there is a possibility. According to the above configuration, the exhaust 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 to the bypass passage until the first catalyst is activated, and once the first catalyst is activated, the exhaust gas flows to the turbine. That is, during normal operation of the power generation engine, the exhaust gas flows to the turbine without passing through the second catalyst. As a result, it is possible to avoid pressure loss caused by restricting the flow of exhaust gas by the second catalyst during normal operation, so that it is possible to suppress the occurrence of supercharging delay.

(5) In one embodiment, the temperature raising device is an electric heater provided in contact with the second catalyst. In the warm-up control, the control device activates the second catalyst by activating the electric heater to raise the temperature of the second catalyst before starting the power generation engine, and after activating the second catalyst, starts the power generation engine. to activate the first catalyst.

According to the above configuration, when there is a request to start the power generation engine, the control device operates the electric heater provided in contact with the second catalyst to start the second catalyst before starting the power generation engine. Activate the catalyst. After activating the second catalyst, the control device starts the power generation engine and activates the first catalyst using the exhaust gas. The exhaust gas at this time passes through the second catalyst and is purified, then flows into the first catalyst and activates the first catalyst. Therefore, even before the first catalyst is activated, unpurified exhaust gas can be prevented from being discharged to the outside of the vehicle.

(6) In one embodiment, the exhaust treatment system for a series hybrid vehicle further includes a rotating electrical machine connected to the crankshaft of the power generation engine. The temperature raising device is an electric heater that is provided upstream of the second catalyst in the exhaust passage and raises the temperature of the exhaust gas. In warm-up control, before starting the power generation engine, the control device motors the power generation engine using a rotating electric machine, operates an electric heater to raise the temperature of the exhaust gas, and activates the second catalyst. After activating 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 motors the power generation engine using a rotating electric machine connected to the crankshaft of the power generation engine, and uses the electric heater to generate exhaust gas from the motor. Raise the temperature. The heated exhaust gas flows into the second catalyst and activates the catalyst. Since the exhaust gas generated by motoring does not contain NOx or the like, it is possible to prevent unpurified exhaust gas from being discharged to the outside of the vehicle even before the second catalyst is activated. After the second catalyst is activated, the power generation engine is started, and the exhaust gas is used to activate the first catalyst. At this time, since the exhaust gas flowing into the first catalyst has been purified by the second catalyst, unpurified exhaust gas is discharged outside the vehicle even before the first catalyst is activated. This can be suppressed.

(7) In one embodiment, during normal operation, the control device operates the power generation engine at a maximum thermal efficiency point where the thermal efficiency of the power generation engine is maximum.

In a series hybrid vehicle, since the engine is provided as a power generation engine, the operating point of the engine can be appropriately controlled regardless of the driving state of the vehicle. In normal operation, efficiency can be increased by operating the power generation engine at the maximum thermal efficiency point.

According to the present disclosure, it is possible to suppress the discharge of unpurified exhaust gas.

1 is a diagram schematically showing the overall configuration of a vehicle according to Embodiment 1. FIG. 1 is a diagram showing a schematic configuration of an engine including an exhaust treatment system in Embodiment 1. FIG. It is a flowchart which shows the procedure of the process performed by ECU in warm-up control. 1 is a diagram showing a schematic configuration of an engine including an exhaust treatment system in which an EHC is provided in a first exhaust passage. FIG. 2 is a diagram showing a schematic configuration of an engine including an exhaust treatment system in which an EHC is provided in a second exhaust passage. 7 is a flowchart showing a procedure of processing executed by the ECU in warm-up control in Modification 1. FIG. FIG. 2 is a diagram showing a schematic configuration of an engine including an exhaust treatment system according to a second embodiment. 7 is a flowchart showing a procedure of processing executed by the ECU in warm-up control in Embodiment 2. FIG. 1 is a diagram showing a schematic configuration of an engine including an exhaust treatment system in which an EH and a three-way catalyst are provided in a first exhaust passage. FIG. 2 is a diagram showing a schematic configuration of an engine including an exhaust treatment system in which an EH and a three-way catalyst are provided in a second exhaust passage. 12 is a flowchart illustrating a procedure of processing executed by the ECU in warm-up control in Modification 3.

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

[Embodiment 1]
<Overall configuration of vehicle>
FIG. 1 is a diagram schematically showing the overall configuration of a vehicle 300 according to the first embodiment. Vehicle 300 is a so-called series hybrid vehicle that includes engine 1 for power generation. 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 "PCU (Power Control Unit)") 4 , a transmission gear 5 , and a drive shaft 6 . , a battery 7, a monitoring unit 9, an ECU (Electronic Control Unit) 200, and a battery ECU 250. Furthermore, vehicle 300 includes a DC/DC converter 110, an auxiliary battery 120, and a low voltage auxiliary device 130.

The engine 1 is, for example, a common rail diesel engine. Note that the engine 1 may be a diesel engine of another type. The engine 1 according to the first embodiment includes four cylinders 12, as shown in FIG. 2, which will be described later.

Each of the first motor generator 2 and the second motor generator 3 is an AC rotating electric machine. The AC rotating electrical machine includes, for example, a permanent magnet type synchronous motor that includes 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 rotates the crankshaft of the engine 1 using electric power from the battery 7 when starting the engine 1 . Further, 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. Further, the AC power generated by the first motor generator 2 may be supplied to the second motor generator 3.

The rotor of the second motor generator 3 is mechanically connected to a drive shaft 6 via a transmission gear 5. The second motor generator 3 rotates the drive shaft 6 using at least one of the power from the battery 7 and the power generated by the first motor generator 2 . Furthermore, the second motor generator 3 can also generate electricity through regenerative braking during braking or reducing acceleration. 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.

PCU 4 converts DC power stored in battery 7 into AC power and supplies it to first motor generator 2 and second motor generator 3 according to a control signal from ECU 200 . Further, 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 the DC power to the battery 7 . PCU 4 is configured to be able to separately control the states (power running and regeneration) of first motor generator 2 and second motor generator 3. For example, the PCU 4 boosts the DC voltage supplied to the inverter 4a provided for the first motor generator 2, the inverter 4b provided for the second motor generator 3, and each inverter to a level higher than the output voltage of the battery 7. The converter 4c is configured to include a converter 4c.

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

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

Monitoring unit 9 monitors the state of battery 7. Specifically, the monitoring unit 9 includes a voltage sensor that detects the voltage of the battery 7, a current sensor that detects the current input/output to the battery 7, and a temperature sensor that detects the temperature of the battery 7. (not shown). 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, steps down the voltage supplied from the power lines PL and NL, and supplies the voltage to the power line EL. That is, DC/DC converter 110 steps down the output voltage of battery 7 to generate power to be supplied to auxiliary battery 120 and low-voltage auxiliary device 130. DC/DC converter 110 is controlled by ECU 200.

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

Low-voltage auxiliary equipment 130 includes a plurality of auxiliary equipment mounted on vehicle 300. The auxiliary equipment includes, for example, audio equipment, video equipment, a navigation device, and a heater 77 (FIG. 2), which will be described later. The low voltage auxiliary device 130 operates by receiving power from the battery 7 and the auxiliary battery 120.

The ECU 200 includes a CPU (Central Processing Unit) 210, memory (RAM (Random Access Memory) and ROM (Read Only Memory)) 220, and an input/output buffer (not shown) for inputting and outputting various signals. be done. The CPU 210 expands the program stored in the ROM into the RAM and executes it. The program stored in the ROM describes the processing to be executed by the CPU 210. ECU 200 causes CPU 210 to execute predetermined calculation processing based on various signals input from the input/output buffer and information stored in memory 220, and causes vehicle 300 to be in a desired state based on the calculation results. Control each device. Note that these controls are not limited to processing by software, but can also be constructed and processed by dedicated hardware (electronic circuits).

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

Battery ECU 250 includes a CPU, a memory, and an input/output buffer for inputting and outputting various signals (none of which are shown). The battery ECU 250 is configured to be able to calculate the SOC (State of Charge) of the battery 7 using the detection results of various sensors from the monitoring unit 9. As a method for calculating the SOC, various known methods can be employed, such as a method based on current value integration (coulomb counting) or a method based on estimation of open circuit voltage (OCV). Battery ECU 250 monitors the SOC of battery 7, and outputs a request to start engine 1 (in other words, a request to generate power) to ECU 200 when SOC of battery 7 becomes less than a predetermined SOC.

Warm-up control is one of the main controls executed by ECU 200 according to the first embodiment. The details of the warm-up control will be described later, but the warm-up control is a control for suppressing unpurified exhaust gas from being discharged to the outside of the vehicle. For example, ECU 200 executes warm-up control when receiving a request to start engine 1. ECU 200 executes warm-up control to appropriately start engine 1 and charge battery 7.

<Engine configuration>
FIG. 2 is a diagram showing a schematic configuration of the engine 1 including the exhaust treatment system according to 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 recirculation device. (hereinafter also referred to as "EGR (Exhaust Gas Recirculation) device") 60.

Engine body 10 includes a plurality of cylinders 12, a common rail 14, and a plurality of injectors 16. In the first embodiment, the engine 1 will be described as an in-line four-cylinder engine, but it may be an engine with other cylinder layouts (for example, V-type or horizontal type).

The plurality of injectors 16 are provided in each of the plurality of cylinders 12, and each of them is a fuel injection device connected to the common rail 14. The common rail 14 stores high-pressure fuel pressurized by a high-pressure pump (not shown). High-pressure fuel stored in the common rail 14 is supplied to the plurality of injectors 16 . The plurality of injectors 16 operate according to control signals IJ1 to IJ4 from the ECU 200 and inject fuel into each cylinder 12.

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

An intake inlet of a compressor 32 of a 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 an intake outlet of the compressor 32 . The compressor 32 supercharges air flowing in from the first intake passage 22 and supplies it to the second intake passage 24 .

One end of an 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 a 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 an intake port of each 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 intercooler 26 and the confluence point of the third intake passage 27 with the EGR passage 66 . Intake throttle valve 29 operates according to a control signal from ECU 200. The intake throttle valve 29 adjusts, for example, the flow rate of intake air flowing into the intake manifold 28 from the third intake passage 27.

The exhaust manifold 50 is connected to an exhaust port of each of the plurality of cylinders 12 of the engine body 10. One end of a first exhaust passage 52 is connected to the exhaust manifold 50 . The other end of the first exhaust passage 52 is connected to an exhaust inlet of the turbine 36 of the supercharger 30.

Supercharger 30 includes a compressor 32 and a turbine 36. A compressor wheel 34 is housed within the housing of the compressor 32, and a turbine wheel 38 is housed within the housing of the turbine 36. The compressor wheel 34 and the turbine wheel 38 are connected by a connecting shaft 42 and rotate together. Therefore, the compressor wheel 34 is rotationally driven 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 outlet of the turbine 36 . The second exhaust passage 54 is provided with an exhaust treatment device 56 . The exhaust treatment device 56 includes a NOx purification catalyst 56a, a DPF (Diesel Particulate Filter) 56b, and three exhaust temperature sensors 56c, 56d, and 56e.

The NOx purification catalyst 56a has a function of purifying nitrogen oxides (NOx) in exhaust gas. As the NOx purification catalyst 56a, for example, an LNT catalyst (Lean Nitrogen oxides Trap catalyst) can be used. For example, the NOx purification catalyst 56a stores NOx in the exhaust gas when the exhaust air-fuel ratio is lean (when there is excess oxygen in the surroundings), and stores NOx in the exhaust gas when the exhaust air-fuel ratio is the stoichiometric air-fuel ratio or rich. (when there is no oxygen in the surrounding area), it has the function of releasing NOx. NOx released from the NOx purification catalyst 56a when the exhaust air-fuel ratio is the stoichiometric air-fuel ratio or rich is purified by being reduced using HC (hydrocarbons) and CO (carbon monoxide) in the exhaust as reducing agents. 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 lean. As the NOx purification catalyst 56a, it is also possible to use, for example, a selective reduction type NOx catalyst (SCR (Selective Catalytic Reduction) catalyst).

The DPF 56b is provided downstream of the NOx purification catalyst 56a in the exhaust flow path (exhaust passage). The DPF 56b collects particulate matter (hereinafter also referred to as "PM (Particulate Matter)") contained in the circulating exhaust gas. The DPF 56b is made of, for example, ceramic and/or stainless steel.

The first exhaust gas temperature sensor 56c is provided upstream of the NOx purification catalyst 56a in the exhaust flow path. The first exhaust gas temperature sensor 56c detects the temperature T1 of 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 downstream of the DPF 56b in the exhaust flow path. 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 a 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 treatment device such as a catalyst that removes specific components from the exhaust gas may be connected to the other end of the third exhaust passage 58.

The EGR device 60 connects the third intake passage 27 and the exhaust manifold 50. 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 controls exhaust gas that is recirculated from the exhaust manifold 50 to the intake manifold 28 via the EGR passage 66 (hereinafter, the exhaust gas that is recirculated to the intake manifold 28 is also referred to as "EGR gas") in accordance with a control signal from the ECU 200. Adjust the flow rate.

The EGR cooler 64 is, for example, a water-cooled or air-cooled heat exchanger that cools EGR gas flowing through the EGR passage 66. The exhaust gas in the exhaust manifold 50 is returned to the intake side as EGR gas via the EGR device 60, thereby lowering the combustion temperature in the cylinder and reducing the amount of NOx produced.

Here, the NOx purification catalyst 56a has a characteristic that its exhaust purification performance increases as its temperature increases. Therefore, in order for the NOx purification catalyst 56a to perform its 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, a second temperature Tth2 described later) or higher, and activated. It is necessary to make it possible. Therefore, in a case where the NOx purification catalyst 56a is not activated, such as when starting the engine 1, unpurified exhaust gas is generated until the NOx purification catalyst 56a is completely warmed up. There is a possibility that it will be ejected outside the vehicle.

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

In the first embodiment, a bypass passage 70 is provided that bypasses exhaust gas flowing from the exhaust manifold 50 upstream of the turbine 36 to a position downstream of the turbine 36 . That is, the bypass passage 70 allows the exhaust gas flowing out from the exhaust manifold 50 to flow to the exhaust 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 upstream of the exhaust treatment device 56 in the exhaust flow path.

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 switch between a first state in which the exhaust gas flowing out from 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. Ru. That is, when the switching valve 72 is in the first state, the exhaust gas flowing out from the exhaust manifold 50 flows to the exhaust treatment device 56 via the bypass passage 70. When the switching valve 72 is in the second state, the exhaust gas flowing out from the exhaust manifold 50 flows to the exhaust treatment device 56 via the turbine 36 . The switching valve 72 switches between the first state and the second state according to a control signal from the ECU 200.

The bypass passage 70 is provided with an electrically heated catalyst (hereinafter also referred to as "EHC (Electrically Heated Catalyst)") 75. EHC 75 includes a three-way catalyst 76 and a heater 77. A three-way catalyst is a catalyst that purifies nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons (HC) contained in exhaust gas. Three-way catalysts reduce NOx to nitrogen and oxygen in the presence of reducing gases (H2, CO or hydrocarbons). Three-way catalysts also oxidize carbon monoxide to carbon dioxide in the presence of an oxidizing gas. Three-way catalysts also oxidize unburned hydrocarbons (HC) to carbon dioxide and water in the presence of an oxidizing gas. In order for the three-way catalyst to oxidize or reduce efficiently, it is desirable that the fuel be completely combusted in the engine body 10 and be combusted at a stoichiometric air-fuel ratio (stoichiometry) with no surplus oxygen (stoichiometric combustion). Further, the heat capacity of the three-way catalyst 76 is configured to be smaller than the heat capacity of the NOx purification catalyst 56a of the exhaust treatment device 56. That is, the three-way catalyst 76 is configured to be activated with a smaller amount of heat than the NOx purification catalyst 56a.

The heater 77 is configured to be able to raise the temperature of the three-way catalyst 76. The heater 77 is, for example, an electric heater provided in contact with the three-way catalyst 76. In the first embodiment, the heater 77 is provided upstream of the three-way catalyst 76 in the exhaust flow path. However, the position where the heater 77 is provided is not limited to the upstream side of the three-way catalyst 76 in the exhaust flow path; for example, it may be provided downstream of the three-way catalyst 76 in the exhaust flow path. . Further, the heater 77 may be provided to cover the three-way catalyst 76, for example.

When ECU 200 receives a request to start engine 1, it executes warm-up control. In the warm-up control, the ECU 200 operates the heater 77 to warm up (raise the temperature of) the three-way catalyst 76 before starting the engine 1 (engine main body 10). For example, the ECU 200 operates the heater 77 with a specified output and determines that the three-way catalyst 76 has been activated when the operation time of the heater 77 has elapsed for a first predetermined time period. The first predetermined period of time is, for example, a period of time during which the temperature of the three-way catalyst 76 can be made equal to or higher than the first temperature Tth1 by operating the heater 77 at the specified output. The first temperature Tth1 is the temperature at which the three-way catalyst 76 is activated. That is, the first predetermined time is a time period during which the amount of heat required to activate the three-way catalyst 76 can be supplied to the three-way catalyst 76 by operating the heater 77 at the specified output. The first predetermined time may be determined based on the specifications of the three-way catalyst 76, or may be determined based on the results of experiments, simulations, or the like. Note that even if a temperature sensor capable of detecting the temperature of the three-way catalyst 76 is further provided and the ECU 200 determines that the three-way catalyst 76 has been activated when the temperature of the three-way catalyst 76 becomes equal to or higher than the first temperature Tth1. good.

Furthermore, before starting the engine 1, the ECU 200 sets the switching valve 72 to the first state so that exhaust gas flows through the bypass passage 70. The timing for setting the switching valve 72 to the first state can be set as appropriate before the engine 1 is started.

When the warm-up of the three-way catalyst 76 is completed, the ECU 200 starts the engine 1 and causes the engine 1 to perform a first operation. The first operation is to operate the engine 1 at a stoichiometric air-fuel ratio and at a low rotational speed. The low rotational speed is a rotational speed lower than the engine rotational speed in the second operation, which will be described later. The engine rotation speed in the first operation is determined by the relationship with the flow rate of exhaust gas that can be appropriately purified by the three-way catalyst 76. When the ECU 200 operates the engine 1 at the stoichiometric air-fuel ratio, the three-way catalyst 76 can efficiently purify the exhaust gas. By operating the engine 1 at a low rotation speed, the ECU 200 limits the flow rate of the exhaust gas to a flow rate that can be appropriately purified by the three-way catalyst 76, thereby making it possible to appropriately purify the exhaust gas. Note that operation at a low rotational speed corresponds to an example of "low speed operation" according to the present disclosure.

The exhaust gas purified by the three-way catalyst 76 flows into the exhaust treatment device 56 . The NOx purification catalyst 56a of the exhaust treatment device 56 is warmed up (temperature raised) by the exhaust gas. The exhaust gas flowing into the NOx purification catalyst 56a is purified by the three-way catalyst 76 as described above. Therefore, even before the NOx purification catalyst 56a is activated, unpurified exhaust gas can be prevented from being discharged from the exhaust treatment device 56.

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 has been activated when the temperature T2 becomes equal to or higher than the second temperature Tth2. When determining that the NOx purification catalyst 56a is activated, the ECU 200 sets the switching valve 72 to the second state and causes the exhaust gas to flow to the turbine 36.

ECU 200 switches engine 1 from first operation to second operation. The second operation is to set the operating point of the engine 1 to a high thermal efficiency point and operate the engine 1 at the operating point. The high thermal efficiency point is, for example, an operating point on the operating line of the engine 1 at which the thermal efficiency is the highest. Since the engine 1 according to the first embodiment is a power generation engine, the operating point of the engine 1 can be set to a high thermal efficiency point regardless of the driving state of the vehicle 300. In addition, in the second operation, the air-fuel ratio is basically operated in a state where the air-fuel ratio is leaner than the stoichiometric air-fuel ratio. After the NOx purification catalyst 56a is activated, the exhaust gas is caused to flow through the turbine 36 and the engine 1 is operated in the second operation, thereby allowing the engine 1 to be operated efficiently. Even in the second operation of the engine 1, the NOx purification catalyst 56a is activated, so that the exhaust gas can be appropriately purified. By operating the engine 1 in the second operation, fuel consumption required for charging the battery 7 can be suppressed. Note that the second operation corresponds to an example of "normal operation" according to the present disclosure.

The "exhaust treatment system" according to the first embodiment includes an exhaust passage (first exhaust passage 52, second exhaust passage 54), a bypass passage 70, a switching valve 72, an EHC 75, and an exhaust treatment device 56. , and an ECU 200.

<Processes executed by ECU in warm-up control>
FIG. 3 is a flowchart showing the procedure of processing executed by ECU 200 in warm-up control. Each step shown in this flowchart is called from a main routine (not shown) and executed when the engine 1 is stopped. Each step of the flowchart shown in FIG. 3 and FIG. 6 described later will be described as being realized by software processing by the ECU 200, but some or all of the steps may be realized by hardware (electrical circuit) fabricated within the ECU 200. It's okay. In addition, below, a step is abbreviated as "S".

When engine 1 is stopped, ECU 200 starts the flowchart. Note that the ECU 200 also starts the flowchart when the vehicle 300 is started.

ECU 200 determines whether there is a request to start engine 1 (S1). If it is determined that there is no request to start the engine 1 (NO in S1), the ECU 200 executes the process in S1 again and monitors whether there is a request to start the engine 1.

If it is determined that there is a request to start the engine 1 (YES in S1), the ECU 200 starts warm-up control. In the warm-up control, the ECU 200 first operates the heater 77 to warm up the three-way catalyst 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, exhaust gas flows through the bypass passage 70. Note that the process in S5 may be executed before the engine 1 is started, and may be executed, for example, before the process in S3 or after an affirmative determination is made in the process in S7, which will be described later.

ECU 200 determines whether three-way catalyst 76 is activated (S7). Specifically, ECU 200 determines whether a first predetermined time has elapsed since heater 77 was activated. If the first predetermined time has not elapsed since the heater 77 was activated (NO in S7), the ECU 200 waits for the first predetermined time to elapse.

If the first predetermined time has elapsed since the heater 77 was activated (YES in S7), the ECU 200 determines that the three-way catalyst 76 has been activated. Note that in this case, the ECU 200 may stop the heater 77. When determining that the three-way catalyst 76 has been activated, the ECU 200 starts the engine 1 and causes the engine 1 to operate in the first operation (S9). The NOx purification catalyst 56a of the exhaust treatment device 56 is warmed up by the exhaust gas generated by the first operation of the engine 1.

The ECU 200 determines whether 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 has been activated when the temperature T2 becomes equal to or higher than the second temperature Tth2.

If the temperature T2 is less 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 becomes 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). This allows exhaust gas to flow through the turbine 36.

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

As described above, in the vehicle 300 equipped with the exhaust treatment system according to the first embodiment, the ECU 200 activates the heater 77 of the EHC 75 before starting the engine 1 when there is a request to start the engine 1 (power generation request). It is operated to activate the three-way catalyst 76. After activating the three-way catalyst 76, the ECU 200 operates the engine 1 in the first operation (stoichiometric air-fuel ratio and low rotational speed) with the switching valve 72 in the first state, and exhausts the exhaust gas through the bypass passage 70. It is made to flow into the exhaust treatment device 56. This exhaust gas warms up the NOx purification catalyst 56a of the exhaust treatment device 56. Since the exhaust gas flowing into the exhaust treatment device 56 is purified by the three-way catalyst 76, unpurified exhaust gas is prevented from being discharged outside the vehicle even before the NOx purification catalyst 56a is activated. can do. Further, by operating the engine 1 in the first operation, the ECU 200 can limit the flow rate of exhaust gas to a flow rate that can be appropriately purified by the three-way catalyst 76, and can efficiently purify the exhaust gas by the three-way catalyst 76.

Additionally, three-way catalysts are generally cheaper than NOx purification catalysts. In the first operation, the three-way catalyst 76 can be used in the EHC 75 by operating the engine 1 with the air-fuel ratio at the stoichiometric air-fuel ratio. Thereby, the cost of the EHC 75 can be suppressed.

When the NOx purification catalyst 56a is activated, the ECU 200 operates the engine 1 in a second operation with the switching valve 72 in the second state. Thereby, the engine 1 can be operated at a high thermal efficiency point. Therefore, fuel consumption required for charging the battery 7 can be suppressed. Furthermore, the exhaust gas treatment device 56 can appropriately purify the exhaust gas.

Furthermore, in the first embodiment, a bypass passage 70 was provided, and the EHC 75 was provided in the bypass passage 70. For example, if the EHC 75 is provided in the first exhaust passage 52 without providing the bypass passage 70, the EHC 75 may restrict the flow of exhaust gas during the second operation, resulting in a pressure loss and a delay in supercharging. In the first embodiment, by providing the bypass passage 70, it is possible to suppress the supercharging delay during the second operation.

Further, by bypassing the turbine 36 when warming up the NOx purification catalyst 56a, it is possible to suppress thermal energy from the exhaust gas from being taken away by the rotation of the turbine 36, for example. Thereby, the NOx purification catalyst 56a can be activated early.

It is also conceivable to employ EHC in the exhaust treatment device 56 and to warm up and activate the NOx purification catalyst 56a of the exhaust treatment device 56 with a heater. However, since the NOx purification catalyst 56a is configured to appropriately 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 also 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 the first embodiment, the power consumption of the heater 77 is sufficient to activate the three-way catalyst 76, which has a smaller heat capacity than the NOx purification catalyst 56a, so the heater activates the NOx purification catalyst 56a. Power consumption can be reduced compared to the case where the Thereby, it is possible to suppress the travelable distance of vehicle 300 from becoming short.

[Modification 1]
In the first embodiment, the bypass passage 70 was provided, and the EHC 75 was provided in the bypass passage 70. However, from the viewpoint of purifying exhaust gas, it is also possible to omit the bypass passage 70. Although the above-mentioned pressure loss 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. Note that when the EHC 75 is provided in the second exhaust passage 54, the EHC 75 is provided at a position upstream of the exhaust treatment device 56 in the exhaust flow path.

FIG. 4 is a diagram showing a schematic configuration of the engine 1 including an exhaust treatment system in which an EHC 75 is provided in the first exhaust passage 52. FIG. 5 is a diagram showing a schematic configuration of the engine 1 including an exhaust treatment system in which an EHC 75 is provided in the second exhaust passage 54. In either configuration, the bypass passage 70 and the switching valve 72 are omitted from 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 warm-up control. In the warm-up control in Modification 1, the ECU 200 activates the three-way catalyst 76 by driving the heater 77 of the EHC 75 before starting the engine 1. After activating the three-way catalyst 76, the ECU 200 starts the engine 1 and operates the engine 1 in the first operation. The ECU 200 operates the engine 1 in the first operation and activates the NOx purification catalyst 56a of the exhaust treatment device 56 with the exhaust gas. Since the exhaust gas when activating the NOx purification catalyst 56a has been purified by the three-way catalyst 76, unpurified exhaust gas is still discharged from the exhaust treatment device 56 even before the NOx purification catalyst 56a is activated. Emissions can be suppressed.

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

FIG. 6 is a flowchart showing the procedure of processing executed by ECU 200 in warm-up control in Modification 1. The flowchart shown in FIG. 6 is the same as the flowchart shown in FIG. 3 by removing the processes in S5 and S13. Other processes are the same as those in the flowchart of FIG. 3, so the same step numbers are given and the description thereof will not be repeated.

As described above, the exhaust treatment system according to Modification 1 can also prevent unpurified exhaust gas from being discharged to the outside of the vehicle.

[Modification 2]
In Embodiment 1 and Modification 1, the engine 1 is a diesel engine. However, the engine 1 is not limited to being a diesel engine, but may be a gasoline engine, for example.

When engine 1 is a gasoline engine, ECU 200 may operate engine 1 in a state where the air-fuel ratio is the stoichiometric air-fuel ratio also in the second operation. If the engine 1 is operated with the air-fuel ratio at the stoichiometric 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 exhaust gas will be reduced. It can be purified efficiently. As mentioned above, three-way catalysts are generally cheaper than NOx purification catalysts. Therefore, when the engine 1 is a gasoline engine, the cost of parts for the exhaust treatment system can be suppressed.

Note that Modification 2 can also be combined with Embodiment 2 and Modification 3, which will be described later.

[Embodiment 2]
In Embodiment 1 and Modifications 1 and 2, warm-up control using the EHC 75 has been described. In Embodiment 2, warm-up control using an EH (Electric Heater) will be described.

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

FIG. 7 is a diagram showing a schematic configuration of an engine 1A including an exhaust treatment system according to the second embodiment. A three-way catalyst 76 and an EH 79 are provided in the bypass passage 70 of the exhaust treatment system of the engine 1A according to the second embodiment. The EH 79 is provided upstream of the three-way catalyst 76 in the exhaust flow path. The EH 79 operates according to a control signal from the ECU 200A and raises the temperature of the exhaust gas flowing through the bypass passage 70. Note that the configuration other than the EH 79 and the ECU 200A is the same as that of the engine 1 according to the first embodiment, and therefore will not be repeatedly described. Note that, similarly to the first embodiment, the heat capacity of the three-way catalyst 76 is configured to be smaller than the heat capacity of the NOx purification catalyst 56a of the exhaust treatment device 56.

When ECU 200A receives a request to start engine 1A, it executes warm-up control. In warm-up control, ECU 200A operates EH 79 before starting engine 1A. ECU 200A sets switching valve 72 to the first state. Then, the ECU 200A executes motoring of the engine 1A using the first motor generator 2. Note that the ECU 200A prohibits fuel injection to the engine 1A (engine main body 10) when motoring is executed. Exhaust gas is discharged from the engine body 10 by motoring. This exhaust gas is heated by EH79, and the three-way catalyst 76 is warmed up by the heated exhaust gas.

The exhaust gas discharged from the engine body 10 by motoring does not contain NOx or the like. Therefore, by warming up the three-way catalyst 76 using the exhaust gas, the three-way catalyst 76 can be activated while suppressing exhaust gas containing NOx and the like from being discharged outside the vehicle.

During motoring, the ECU 200A monitors whether the three-way catalyst 76 is activated. Specifically, the ECU 200A operates the EH79 at a specified output, and calculates the time from the start of motoring (that is, from the time when the exhaust gas heated by the EH79 starts flowing into the three-way catalyst 76). time) has passed a predetermined second predetermined time, it is determined that the three-way catalyst 76 has been activated. The second predetermined time is, for example, a time period during which the temperature of the three-way catalyst 76 can be made equal to or higher than the first temperature Tth1 when the EH 79 is operated at the specified output and motoring is executed. The second predetermined time may be determined based on the specifications of the three-way catalyst 76, or may be determined based on the results of experiments, simulations, or the like. Further, a temperature sensor capable of detecting the temperature of the three-way catalyst 76 is further provided, and even if the ECU 200A determines that the three-way catalyst 76 is activated when the temperature of the three-way catalyst 76 becomes equal to or higher than the first temperature Tth1. good. When determining that the three-way catalyst 76 has been activated, the ECU 200A starts the engine 1A and causes the engine 1A to operate in the first operation.

The exhaust gas produced by the first operation of the engine 1A is appropriately purified by the activated three-way catalyst 76. Then, the exhaust gas purified by the three-way catalyst 76 flows into the exhaust treatment device 56. The NOx purification catalyst 56a of the exhaust treatment device 56 is warmed up (temperature raised) by the exhaust gas. The exhaust gas flowing into the NOx purification catalyst 56a is purified by the three-way catalyst 76 as described above. Therefore, even before the NOx purification catalyst 56a is activated, unpurified exhaust gas can be prevented from being discharged from the exhaust treatment device 56.

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 has been activated when the temperature T2 becomes equal to or higher than the second temperature Tth2. When determining 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.

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

As described above, when the NOx purification catalyst 56a is warmed up, the turbine 36 is bypassed to allow the exhaust gas to flow. As a result, it is possible to suppress thermal energy from the exhaust gas being taken away due to the rotation of the turbine 36, for example, so that the NOx purification catalyst 56a can be activated earlier than when the turbine 36 is not bypassed. That is, since the time required for motoring can be shortened, power consumption of the battery 7 can be suppressed, and a decrease in the travelable distance of the vehicle 300A can be suppressed.

<Processes executed by ECU in warm-up control>
FIG. 8 is a flowchart showing a procedure of processing executed by ECU 200A in warm-up control in the second embodiment. Each step shown in this flowchart is called from a main routine (not shown) and executed when the engine 1 is stopped. Each step of the flowchart shown in FIG. 8 and FIG. 11 described later will be described as being realized by software processing by the ECU 200A. It's okay.

When the engine 1A is stopped, the ECU 200A starts the flowchart. Note that the ECU 200A also starts the flowchart when the vehicle 300A is started.

ECU 200A determines whether there is a request to start engine 1A (S51). If it is determined that there is no request to start the engine 1A (NO in S51), the ECU 200A executes the process of S51 again and monitors whether there is a request to start the engine 1A.

If it is determined that there is a request to start the engine 1A (YES in S51), the ECU 200A starts warm-up control. In the warm-up control, the ECU 200A first sets the switching valve 72 to the first state (S53). Then, the ECU 200A operates the EH 79 (S55). Note that the order of execution of the processes in S53, S55, and S57, which will be described later, may be changed as appropriate.

Then, the ECU 200A executes motoring of the engine 1A using the first motor generator 2 (S57). In this case, ECU 200A prohibits fuel injection to engine 1A. Exhaust gas discharged from the engine body 10 by motoring flows through the bypass passage 70 and is heated by the EH 79. Then, the heated exhaust gas flows into the three-way catalyst 76, thereby warming up the three-way catalyst 76.

The ECU 200A determines whether the three-way catalyst 76 is activated (S58). Specifically, the ECU 200A operates the EH 79 with a specified output and determines whether a second predetermined time has elapsed since motoring was started. If the ECU 200A activates the EH 79 and the second predetermined time has not elapsed since the start of motoring (NO in S58), the ECU 200A waits for the second predetermined time to elapse.

If the EH 79 is activated and a second predetermined time period has elapsed since the start of motoring (YES in S58), the ECU 200A determines that the three-way catalyst 76 has been activated. When determining that the three-way catalyst 76 has been activated, the ECU 200A starts the engine 1A and causes the engine 1A to operate in the first operation (S59). Exhaust gas produced by the first operation of the engine 1A is purified by the three-way catalyst 76 and flows into the exhaust treatment device 56. Then, the NOx purification catalyst 56a of the exhaust treatment device 56 is warmed up by this exhaust gas.

The ECU 200A determines whether the NOx purification catalyst 56a of the exhaust treatment device 56 has been activated (S60). Specifically, the ECU 200A monitors the temperature T2 detected by the second exhaust gas temperature sensor 56d, and determines that the NOx purification catalyst 56a has been activated when the temperature T2 becomes equal to or higher than the second temperature Tth2.

If the temperature T2 is less than the second temperature Tth2 (NO in S60), the ECU 200A waits for the temperature T2 to become equal to or higher than the second temperature Tth2. When the temperature T2 becomes 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 engine 1A can be operated efficiently while the exhaust gas is appropriately purified by the exhaust treatment device 56.

As described above, in the vehicle 300A equipped with the exhaust treatment system according to the second embodiment, when there is a request to start the engine 1A (power generation request), the ECU 200A sets the switching valve 72 to the first state and sets the switching valve 72 to the first state. 1 Motoring of engine 1A using motor generator 2 is executed. Then, the ECU 200A raises the temperature of the exhaust gas discharged from the engine body 10 by motoring at EH79. Then, the three-way catalyst 76 is activated with the heated exhaust gas. Since the exhaust gas discharged from the engine body 10 by motoring does not contain NOx or the like, the three-way catalyst 76 can be activated without exhausting the exhaust gas containing NOx or the like to the outside of the vehicle. Then, after activating the three-way catalyst 76, the ECU 200A starts the engine 1A to perform the first operation (stoichiometric air-fuel ratio and low rotational speed) with the switching valve 72 in the first state, and operates the engine 1A through the bypass passage 70. to cause the exhaust gas to flow into the exhaust treatment device 56. This exhaust gas warms up the NOx purification catalyst 56a of the exhaust treatment device 56. Since the exhaust gas flowing into the exhaust treatment device 56 is purified by the three-way catalyst 76, unpurified exhaust gas is prevented from being discharged outside the vehicle even before the NOx purification catalyst 56a is activated. can do. Further, by first operating the engine 1A, the ECU 200A can limit the flow rate of exhaust gas to a flow rate that can be appropriately purified by the three-way catalyst 76, and can efficiently purify the exhaust gas by the three-way catalyst 76.

Further, by bypassing the turbine 36 when warming up the NOx purification catalyst 56a, it is possible to suppress thermal energy from the exhaust gas from being taken away by the rotation of the turbine 36, for example. 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 flowing exhaust gas through the turbine 36, the engine 1A can be operated at an operating point with good thermal efficiency. Thereby, fuel consumption required for charging the battery 7 can be suppressed.

[Modification 3]
In the second embodiment, a bypass passage 70 is provided, and an EH 79 and a three-way catalyst 76 are provided in the bypass passage 70. However, the EH 79 and the three-way catalyst 76 may be provided in the first exhaust passage 52 or the second exhaust passage 54. Note that when the EH 79 and the three-way catalyst 76 are provided in the second exhaust passage 54, the EH 79 and the three-way catalyst 76 are provided at a position upstream of the exhaust treatment device 56 in the exhaust flow path.

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

In any of the above configurations, when there is a request to start the engine 1A, the ECU 200A executes warm-up control. In the warm-up control in modification 3, the ECU 200A motors the engine 1A using the first motor generator 2 while operating the EH 79 before starting the engine 1A. The exhaust gas discharged from the engine body 10 by motoring is heated by the EH 79, and the three-way catalyst 76 is warmed up by the heated exhaust gas. The exhaust gas discharged from the engine body 10 by motoring does not contain NOx or the like. Therefore, the three-way catalyst 76 can be activated without discharging exhaust gas containing NOx and the like to the outside of the vehicle.

When the three-way catalyst 76 is activated, the ECU 200A starts the engine 1A and operates the engine 1A in the first operation. The exhaust gas produced by the first operation of the engine 1A is appropriately purified by the activated three-way catalyst 76. Then, the exhaust gas purified by the three-way catalyst 76 flows into the exhaust treatment device 56. The NOx purification catalyst 56a of the exhaust treatment device 56 is warmed up (temperature raised) by the exhaust gas. The exhaust gas flowing into the NOx purification catalyst 56a is purified by the three-way catalyst 76 as described above. Therefore, even before the NOx purification catalyst 56a is activated, unpurified exhaust gas can be prevented from being discharged from the exhaust treatment device 56.

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 has been activated when the temperature T2 becomes equal to or higher than the second temperature Tth2. When determining 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 performing the second operation of the engine 1A, fuel consumption required for charging the battery 7 can be suppressed. The exhaust gas at this time is appropriately purified by the exhaust treatment device 56.

FIG. 11 is a flowchart showing the procedure of processing executed by the ECU 200A in warm-up control in Modification 3. The flowchart shown in FIG. 11 is the same as the flowchart shown in FIG. 8, with the processes of S53 and S61 deleted. Other processes are the same as those in the flowchart of FIG. 8, so the same step numbers are given and the description thereof will not be repeated.

As described above, the exhaust treatment system according to the third modification can also prevent unpurified exhaust gas from being discharged to the outside of the vehicle.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the description of the embodiments described above, and it is intended that all changes within the meaning and scope equivalent to the claims are included.

1, 1A engine, 2 first motor generator, 3 second motor generator, 4 PCU, 4a, 4b inverter, 4c converter, 5 transmission gear, 6 drive shaft, 7 battery, 8 cell, 9 monitoring unit, 10 engine main body, 12 cylinder, 14 common rail, 16 injector, 20 air cleaner, 22 first intake passage, 24 second intake passage, 26 intercooler, 27 third 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 first exhaust passage, 54 second exhaust passage, 56 exhaust treatment device, 56a NOx purification catalyst, 56c exhaust temperature sensor, 56c first Exhaust temperature sensor, 56d Second exhaust temperature sensor, 56e Third exhaust temperature sensor, 58 Third exhaust passage, 60 EGR device, 62 EGR valve, 64 EGR cooler, 66 EGR passage, 70 Bypass passage, 72 Switching valve, 75 EHC , 76 three-way catalyst, 77 heater, 79 EH, 110 DC/DC converter, 120 auxiliary battery, 130 low-voltage auxiliary device, 200 ECU, 210 CPU, 220 memory, 250 battery ECU, 300,300A vehicle.

Claims (9)

An exhaust treatment system for a series hybrid vehicle equipped with a power generation engine,
a first catalyst provided in the exhaust passage of the power generation engine;
a second catalyst provided upstream of the first catalyst in the exhaust passage;
a temperature raising device configured to be able to raise the temperature of the second catalyst or the exhaust gas flowing into the second catalyst;
comprising a control device that controls the power generation engine and the temperature raising device,
When there is a request to start the power generation engine, the control device executes warm-up control and then operates the power generation engine in normal operation;
In the warm-up control, the control device:
Activating the second catalyst by operating the temperature raising device before starting the power generation engine,
After activating the second catalyst, start the power generation engine to activate the first catalyst ,
The first catalyst is configured to be able to purify exhaust gas during the normal operation,
The second catalyst has a smaller heat capacity than the first catalyst, and is configured to be able to purify exhaust gas during low-speed operation in which the power generation engine is operated at a lower rotational speed than the normal operation,
In the warm-up control, the control device:
Activating the second catalyst by operating the temperature raising device before starting the power generation engine,
After activating the second catalyst, start the power generation engine and operate the power generation engine at the low speed to activate the first catalyst,
An exhaust treatment system for a series hybrid vehicle , wherein the power generation engine is operated in the normal operation after activating the first catalyst . The second catalyst is a three-way catalyst,
In the warm-up control, the control device:
Activating the second catalyst by operating the temperature raising device before starting the power generation engine,
After activating the second catalyst, start the power generation engine, and operate the power generation engine at low speed and at a stoichiometric air-fuel ratio to activate the first catalyst. activate,
The exhaust treatment system for a series hybrid vehicle according to claim 1 , wherein the power generation engine is operated in the normal operation after activating the first catalyst. The power generation engine has a turbocharger,
The first catalyst is provided downstream of the turbine of the turbocharger in the exhaust passage,
The exhaust treatment system of the series hybrid vehicle is:
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;
further comprising a switching valve configured to be able to switch between a first state in which exhaust gas flows through the bypass passage and a second state in which exhaust gas flows not 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:
the switching valve is in the first state until the first catalyst is activated;
The exhaust treatment system for a series hybrid vehicle according to claim 1 or 2 , wherein when the first catalyst is activated, the switching valve is placed in the second state. The temperature raising device is an electric heater provided in contact with the second catalyst,
In the warm-up control, the control device:
Before starting the power generation engine, operate the electric heater to raise the temperature of the second catalyst and activate it,
The exhaust gas of the series hybrid vehicle according to any one of claims 1 to 3 , wherein after activating the second catalyst, the power generation engine is started to activate the first catalyst. processing system. further comprising a rotating electric machine connected to the crankshaft of the power generation engine,
The temperature raising device is an electric heater that is provided upstream of the second catalyst in the exhaust passage and raises the temperature of the exhaust gas,
In the warm-up control, the control device:
Before starting the power generation engine, motoring the power generation engine using the rotating electric machine,
activating the second catalyst by operating the electric heater to raise the temperature of the exhaust gas;
The exhaust gas of the series hybrid vehicle according to any one of claims 1 to 3 , wherein after activating the second catalyst, the power generation engine is started to activate the first catalyst. processing system. The series hybrid according to any one of claims 1 to 5 , wherein the control device operates the power generation engine at a maximum thermal efficiency point where the thermal efficiency of the power generation engine is maximum during the normal operation. Vehicle exhaust treatment system. An exhaust treatment system for a series hybrid vehicle equipped with a power generation engine,
a first catalyst provided in the exhaust passage of the power generation engine;
a second catalyst provided upstream of the first catalyst in the exhaust passage;
a temperature raising device configured to be able to raise the temperature of the second catalyst or the exhaust gas flowing into the second catalyst;
comprising a control device that controls the power generation engine and the temperature raising device,
When there is a request to start the power generation engine, the control device executes warm-up control and then operates the power generation engine in normal operation;
In the warm-up control, the control device:
Activating the second catalyst by operating the temperature raising device before starting the power generation engine,
After activating the second catalyst, start the power generation engine to activate the first catalyst;
The power generation engine has a turbocharger,
The first catalyst is provided downstream of the turbine of the turbocharger in the exhaust passage,
The exhaust treatment system of the series hybrid vehicle is:
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;
further comprising a switching valve configured to be able to switch between a first state in which exhaust gas flows through the bypass passage and a second state in which exhaust gas flows not 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:
the switching valve is in the first state until the first catalyst is activated;
An exhaust treatment system for a series hybrid vehicle, wherein when the first catalyst is activated, the switching valve is placed in the second state. further comprising a rotating electric machine connected to the crankshaft of the power generation engine,
The temperature raising device is an electric heater that is provided upstream of the second catalyst in the exhaust passage and raises the temperature of the exhaust gas,
In the warm-up control, the control device:
Before starting the power generation engine, motoring the power generation engine using the rotating electric machine,
activating the second catalyst by operating the electric heater to raise the temperature of the exhaust gas;
The exhaust treatment system for a series hybrid vehicle according to claim 7, wherein after activating the second catalyst, the power generation engine is started to activate the first catalyst. An exhaust treatment system for a series hybrid vehicle equipped with a power generation engine,
a first catalyst provided in the exhaust passage of the power generation engine;
a second catalyst provided upstream of the first catalyst in the exhaust passage;
a temperature raising device configured to be able to raise the temperature of the second catalyst or the exhaust gas flowing into the second catalyst;
comprising a control device that controls the power generation engine and the temperature raising device,
When there is a request to start the power generation engine, the control device executes warm-up control and then operates the power generation engine in normal operation;
In the warm-up control, the control device:
Activating the second catalyst by operating the temperature raising device before starting the power generation engine,
After activating the second catalyst, start the power generation engine to activate the first catalyst;
further comprising a rotating electric machine connected to the crankshaft of the power generation engine,
The temperature raising device is an electric heater that is provided upstream of the second catalyst in the exhaust passage and raises the temperature of the exhaust gas,
In the warm-up control, the control device:
Before starting the power generation engine, motoring the power generation engine using the rotating electric machine,
activating the second catalyst by operating the electric heater to raise the temperature of the exhaust gas;
An exhaust treatment system for a series hybrid vehicle, wherein after activating the second catalyst, the power generation engine is started to activate the first catalyst.

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