control device

Abstract

The object of the present invention is to provide a control device that can reduce the rate of catalyst degradation. [Solution] The present invention is a control device for a vehicle comprising an engine, a motor generator, a motor, and a catalyst. The motor generator generates electricity using the power generated by the engine. The motor generates power to move the vehicle using the electricity generated by the motor generator. The catalyst purifies the exhaust gas flowing out of the engine. In motoring operation, the engine is operated by an external force applied from outside the engine without burning fuel. In firing operation, the engine is operated by burning fuel. If the temperature of the catalyst is higher than a predetermined temperature while motoring is in progress, the control device stops the motoring operation and performs the firing operation.

Description

[Technical Field]

[0001] The present invention relates to a control device. [Background Art]

[0002] As an invention relating to a conventional control device, for example, the control device described in Patent Document 1 is known. This control device controls a hybrid vehicle equipped with an internal combustion engine and an electric motor as power sources, and when a predetermined condition that enables stopping of the internal combustion engine that has been operated by firing is satisfied, the control device for a hybrid vehicle is configured such that the length of the period from the satisfaction of the condition to the actual stop of the internal combustion engine is changed according to the temperature of the exhaust purification catalyst at that time. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2022-72799 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In the engine control device as described above, there is a demand to reduce the progression rate of catalyst deterioration.

[0005] Accordingly, an object of the present invention is to provide a control device capable of reducing the progression rate of catalyst deterioration. [Means for Solving the Problem]

[0006] A first aspect provides: A control device for a vehicle, the vehicle comprising an engine, a motor generator, a motor, and a catalyst, the motor generator generates electric power using power generated by the engine, the motor generates power for causing the vehicle to travel using electric power generated by the motor generator, The catalyst purifies the exhaust gas flowing out of the engine, In motoring operation, the engine is operated by an external force applied from outside the engine without burning fuel. During firing, the engine is operated by burning fuel. The control device, when performing the motoring operation, stops the motoring operation and performs the firing operation if the temperature of the catalyst is higher than a predetermined temperature. It is a control device.

[0007] The second aspect is, A control device for a vehicle comprising an engine, a motor generator, a motor, a catalyst, and an EGR valve, The motor generator generates electricity using the power generated by the engine, The motor generates power to move the vehicle using the electricity generated by the motor generator. The engine is connected to an intake path and an exhaust path. The EGR path connects the intake path and the exhaust path. The EGR valve adjusts the amount of exhaust gas flowing from the exhaust path to the intake path. The catalyst is provided in the exhaust path and purifies the exhaust gas flowing out from the engine. In motoring operation, the engine is operated by an external force applied from outside the engine without burning fuel. When the motoring operation is performed when the temperature of the catalyst is higher than a predetermined temperature, the control device controls the EGR valve so that exhaust gas flows from the exhaust path to the intake path. It is a control device.

[0008] The third aspect is, The aforementioned vehicle further includes a throttle valve, The throttle valve adjusts the amount of air flowing from the intake path into the engine. The control device controls the throttle valve such that an opening degree of the throttle valve when performing the motoring operation when a temperature of the catalyst is higher than a predetermined temperature is smaller than the opening degree of the throttle valve when performing the motoring operation when the temperature of the catalyst is lower than the predetermined temperature, The control device according to the second aspect. Effects of the Invention

[0009] According to the present invention, the progression rate of catalyst deterioration can be reduced. Brief Description of the Drawings

[0010] [Figure 1] Figure 1 is a schematic diagram of vehicles 1 and 1a. [Figure 2] Figure 2 is a schematic diagram of engine systems 2 and 2a. [Figure 3] Figure 3 is a timing chart of the operation of the engine system 2. [Figure 4] Figure 4 is a flowchart executed by the control device 100. [Figure 5] Figure 5 is a flowchart executed by the control device 100. Mode for Carrying Out the Invention

[0011] (Embodiment) [Structure of Vehicle 1] Hereinafter, the structure of a vehicle 1 including a control device 100 according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 is a schematic diagram of vehicles 1 and 1a. Figure 2 is a schematic diagram of engine systems 2 and 2a.

[0012] The vehicle 1 is, for example, a four-wheeled motor vehicle. The vehicle 1 is a hybrid vehicle. In the present embodiment, the vehicle 1 is a series hybrid vehicle. As shown in FIG. 1, the vehicle 1 includes an engine system 2, a motor generator 3, an inverter 4, a battery 5, a motor 6, a power transmission device 7, a left front wheel 8L, a right front wheel 8R, and a control device 100 (see FIG. 2).

[0013] As shown in FIG. 2, the engine system 2 includes an engine 20, a throttle valve 22, a catalyst 24, and an EGR (Exhaust Gas Recirculation) valve 26. The engine 20 generates power using gasoline as fuel. The engine 20 is a port injection type engine. The engine 20 does not generate power to be transmitted to the left front wheel 8L and the right front wheel 8R. The engine 20 is a four-cycle engine. Although the engine 20 is an engine including one or more cylinders, it is generally an engine including a plurality of cylinders. When the engine 20 is an engine including a plurality of cylinders, the plurality of cylinders may be arranged in one row, two rows, or four rows.

[0014] An intake path R1 and an exhaust path R2 are connected to the engine 20. The intake path R1 is a space through which air or an air-fuel mixture passes. The exhaust path R2 is a space through which exhaust gas passes.

[0015] The throttle valve 22 is an electronic throttle that operates under the control of the control device 100 described later. The throttle valve 22 is provided in the intake path R1. The throttle valve 22 adjusts the amount of air flowing into the engine 20 from the intake path R1.

[0016] The catalyst 18 is a three-way catalyst. The catalyst 18 is provided in the exhaust path R2. The catalyst 18 converts carbon monoxide, hydrocarbons, and nitrogen oxides contained in exhaust gas flowing out from the engine 20 into harmless substances through oxidation reaction and reduction reaction. Thereby, the catalyst 18 purifies the exhaust gas flowing out from the engine 20.

[0017] The EGR path R3 connects the intake path R1 and the exhaust path R2. Exhaust gas flows from the exhaust path R2 through the EGR path R3 and into the intake path R1.

[0018] The EGR valve 26 is an electromagnetic valve that operates under the control of the control device 100, which will be described later. The EGR valve 26 is located in the EGR path R3. The EGR valve 26 adjusts the amount of exhaust gas flowing from the exhaust path R2 to the intake path R1.

[0019] The motor generator 3 is connected to the engine 20. The motor generator 3 generates electricity using the power produced by the engine 20. The motor generator 3 is, for example, an AC generator. The motor generator 3 also functions as a motor to start the engine 20.

[0020] Battery 5 stores the power generated by the motor generator 3. Battery 5 is a rechargeable and dischargeable secondary battery. Battery 5 is, for example, a lithium-ion battery or a solid-state battery.

[0021] Motor 6 generates power to move vehicle 1 using the electricity generated by motor generator 3. In this embodiment, motor 6 generates power transmitted to the left front wheel 8L and the right front wheel 8R of vehicle 10. Motor 6 generates power to move vehicle 10 using the electricity stored in battery 5. However, in addition to the electricity generated by motor generator 3, battery 5 may also store electricity generated by motor 6 when vehicle 10 decelerates. Motor 6 is, for example, an AC motor.

[0022] The inverter 4 controls the motor 6. In this embodiment, the inverter 4 converts the alternating current generated by the motor generator 3 into a direct current and supplies the direct current to the battery 5. As a result, the battery 5 is charged by the power generated by the motor generator 3. The inverter 4 also converts the direct current generated by the battery 5 into an alternating current and supplies the alternating current to the motor 6. The motor 6 operates using the alternating current supplied by the inverter 4.

[0023] The power generated by the motor 6 is transmitted to the power transmission device 7. The power transmission device 7 transmits the power generated by the motor 6 to the left front wheel 8L and the right front wheel 8R. Such a power transmission device 7 is, for example, a reduction gear and a differential.

[0024] The control device 100 controls the operation of the engine system 2. In this embodiment, the control device 100 controls the amount of fuel injected by the injector. The control device 100 controls the timing of the spark plug discharge. The control device 100 controls the opening degree of the throttle valve 22. The control device 100 controls the opening degree of the EGR valve 26. The control device 100 is, for example, an ECU (Engine Control Unit) and includes a circuit board and electronic components.

[0025] [Operation of Engine System 2] Next, the operation of engine system 2 will be explained with reference to the diagrams. Figure 3 is a timing chart of the operation of engine system 2.

[0026] Motoring and firing operations are defined as follows: In motoring operation, the engine 20 is operated by an external force applied from outside the engine 20 without burning fuel. In this embodiment, the engine 20 is operated by the motor generator 3 rotating the crankshaft of the engine 20. In motoring operation, the injectors do not inject fuel, and the spark plugs do not generate sparks. In motoring operation, the engine 20 does not generate power. In firing operation, the engine 20 is operated by burning fuel. In firing operation, the injectors inject fuel, and the spark plugs generate sparks. In firing operation, the engine 20 generates power.

[0027] Between times t0 and t1, vehicle 1 is driven by the power generated by motor 6 with engine 20 stopped. Between times t0 and t1, fuel injection is not taking place (hereinafter referred to as the cut-off state).

[0028] At time t1, the control device 100 starts the engine 20. Between times t1 and t2, the vehicle 1 is driven by the power generated by the motor 6 while the engine 20 is firing. Between times t1 and t2, fuel injection is occurring (hereinafter referred to as the injection state). Between times t1 and t2, the temperature of the catalyst 18 (hereinafter referred to as the catalyst temperature) is rising over time.

[0029] Between times t2 and t3, the control device 100 causes the engine 20 to perform motoring. Between times t2 and t3, the injectors are cut off, resulting in a lean air-fuel ratio. However, when the catalyst temperature is high and the air-fuel ratio is lean, the catalyst 18 is prone to deterioration. Therefore, at time t3, the control device 100 starts the engine 20. Between times t3 and t4, the vehicle 1 is driven by the power generated by the motor 6 while the engine 20 is firing. Between times t3 and t4, the injectors are in the injection state. Between times t3 and t4, the catalyst temperature decreases slightly, and the air-fuel ratio becomes slightly richer. This suppresses the deterioration of the catalyst 18. The dotted line shows the change in catalyst temperature when motoring is performed between times t3 and t4.

[0030] Between times t4 and t5, the control device 100 stops the engine 20. However, it is necessary to generate negative pressure in the brake booster of vehicle 1. Therefore, between times t5 and t6, the control device 100 causes the engine 20 to perform a motoring operation. However, because the catalyst temperature is high, the deterioration of the catalyst 18 is likely to progress when the motoring operation is performed. Therefore, at time t6, the control device 100 starts the engine 20. That is, between times t6 and t7, the control device 100 causes the engine 20 to perform a firing operation. This makes the air-fuel ratio rich, thus suppressing the deterioration of the catalyst. Subsequently, when the catalyst temperature falls below a predetermined temperature Tth, the control device 100 stops the engine 20.

[0031] When the catalyst temperature is high and the air-fuel ratio is lean, the deterioration of the catalyst 18 is likely to progress. This condition is most likely to occur during the period from time t5 to t6. In other words, when motoring is performed when the catalyst temperature is high, the air-fuel ratio is likely to become lean at high catalyst temperatures, and the deterioration of the catalyst 18 is likely to progress. Therefore, at times t6 to t7, if the catalyst temperature (temperature of catalyst 18) is higher than a predetermined temperature Tth while motoring is being performed, the control device 100 stops the motoring operation and performs firing.

[0032] Next, the operation of the control device 100 will be explained with reference to the drawings. Figure 4 is a flowchart of the actions performed by the control device 100.

[0033] First, the control device 100 determines whether or not the engine 20 is performing motoring operations (step S1). If the engine 20 is performing motoring operations, the process proceeds to step S2. If the engine 20 is not performing motoring operations, the process returns to step S1.

[0034] When the engine 20 is performing motoring operations, the control device 100 estimates the catalyst temperature (step S2). More specifically, a memory circuit (not shown) stores a map showing the relationship between the rotational speed of the engine 20, the load factor, and the catalyst temperature. Based on this, the control device 100 determines the rotational speed of the engine 20 based on the crank angle signal output from a crank angle sensor (not shown). The control device 100 determines the load factor based on the intake pressure signal output from an intake pressure sensor (not shown). Then, the control device 100 estimates the catalyst temperature based on the determined rotational speed and load factor of the engine 20.

[0035] Next, the control device 100 determines whether the catalyst temperature is higher than a predetermined temperature Tth (step S3). The predetermined temperature Tth is the temperature at which the degradation of the catalyst 18 progresses in a lean state. The predetermined temperature Tth is, for example, 800°C. If the catalyst temperature is higher than the predetermined temperature Tth, the process proceeds to step S4. If the catalyst temperature is not higher than the predetermined temperature Tth, the process proceeds to step S7.

[0036] If the catalyst temperature is higher than a predetermined temperature Tth, the control device 100 causes the engine 20 to perform a firing operation (step S4). That is, the control device 100 injects fuel into the injector and generates a spark at the spark plug.

[0037] Next, the control device 100 determines whether the catalyst temperature is higher than a predetermined temperature Tth (step S5). If the catalyst temperature is higher than the predetermined temperature Tth, the process returns to step S5. If the catalyst temperature is not higher than the predetermined temperature Tth, the process proceeds to step S6.

[0038] If the catalyst temperature is not higher than a predetermined temperature Tth, the control device 100 stops the firing operation of the engine 20 (step S6). As a result, the engine 20 stops. After this, the process ends.

[0039] If the catalyst temperature in step S3 is not higher than a predetermined temperature Tth, the control device 100 causes the engine 20 to continue motoring (step S7). That is, the control device 100 causes the motor generator 3 to rotate the crankshaft of the engine 20 without injecting fuel into the injectors or generating a spark in the spark plugs.

[0040] Next, the control device 100 determines whether a predetermined time has elapsed since the start of the motoring operation (step S8). The predetermined time is, for example, the time required for sufficient negative pressure to be generated in the brake booster. If the predetermined time has elapsed since the start of the motoring operation, the process proceeds to step S9. If the predetermined time has not elapsed since the start of the motoring operation, the process returns to step S8.

[0041] If a predetermined time has elapsed since the start of motoring operation, the control device 100 instructs the engine 20 to stop motoring operation (step S9). As a result, the engine 20 stops. After this, this process ends.

[0042] [effect] According to the control device 100 of this embodiment, the rate of deterioration of the catalyst 18 can be reduced. More specifically, when the catalyst temperature is high and the air-fuel ratio is lean, the deterioration of the catalyst 18 is likely to progress. Therefore, when the catalyst temperature is higher than a predetermined temperature Tth while the control device 100 is performing a motoring operation, it stops the motoring operation and performs a firing operation. As a result, the air-fuel ratio is no longer lean. Consequently, the deterioration of the catalyst 18 is less likely to progress.

[0043] (modified version) Next, we will describe vehicle 1a relating to the first modified example with reference to the drawings. Figure 5 is a flowchart of the actions performed by the control device 100.

[0044] In vehicle 1, if the catalyst temperature (temperature of catalyst 18) is higher than a predetermined temperature Tth while motoring is being performed, the control device 100 stops the motoring operation and performs firing. On the other hand, in vehicle 1a, when motoring is performed when the catalyst temperature (temperature of catalyst 18) is higher than a predetermined temperature Tth, the control device 100 controls the EGR valve 26 so that exhaust flows from the exhaust path R2 to the intake path R1. At this time, the control device 100 controls the throttle valve 22 so that the opening degree of the throttle valve 22 when motoring is performed when the catalyst temperature (temperature of catalyst 18) is higher than a predetermined temperature Tth is smaller than the opening degree of the throttle valve 22 when motoring is performed when the catalyst temperature (temperature of catalyst 18) is lower than a predetermined temperature Tth.

[0045] As a result, exhaust gas mixes with intake gas. The proportion of oxygen in exhaust gas is less than the proportion of oxygen in intake gas. Therefore, the proportion of oxygen in the gas mixture of exhaust and intake gas is less than the proportion of oxygen in intake gas. Consequently, the progression of deterioration of catalyst 18 is suppressed.

[0046] Furthermore, since exhaust gases mix with intake air, the intake pressure increases. Therefore, the control device 100 reduces the opening of the throttle valve 22. This reduces the amount of air passing through the throttle valve 22. As a result, the intake pressure does not rise as easily. This allows sufficient negative pressure to be generated in the brake booster.

[0047] Next, the operation of the control device 100 will be explained with reference to the drawings. The control device 100 determines whether or not the engine 20 is performing motoring operation (step S1). If the engine 20 is performing motoring operation, the process proceeds to step S2. If the engine 20 is not performing motoring operation, the process returns to step S1.

[0048] When the engine 20 is performing motoring operations, the control device 100 estimates the catalyst temperature (step S2). More specifically, a memory circuit (not shown) stores a map showing the relationship between the rotational speed of the engine 20, the load factor, and the catalyst temperature. Based on this, the control device 100 determines the rotational speed of the engine 20 based on the crank angle signal output from a crank angle sensor (not shown). The control device 100 determines the load factor based on the intake pressure signal output from an intake pressure sensor (not shown). Then, the control device 100 estimates the catalyst temperature based on the determined rotational speed and load factor of the engine 20.

[0049] Next, the control device 100 determines whether the catalyst temperature is higher than a predetermined temperature Tth (step S3). The predetermined temperature Tth is the temperature at which the degradation of the catalyst 18 progresses in a lean state. The predetermined temperature Tth is, for example, 800°C. If the catalyst temperature is higher than the predetermined temperature Tth, the process proceeds to step S4. If the catalyst temperature is not higher than the predetermined temperature Tth, the process proceeds to step S7.

[0050] If the catalyst temperature is higher than a predetermined temperature Tth, the control device 100 causes the engine 20 to continue motoring (step S14). That is, the control device 100 causes the motor generator 3 to rotate the crankshaft of the engine 20 without injecting fuel into the injectors or generating a spark in the spark plugs.

[0051] Next, the control device 100 increases the opening degree of the EGR valve 26 (step S15) and decreases the opening degree of the throttle valve 22 (step S16).

[0052] Next, the control device 100 determines whether a predetermined time has elapsed since the start of the motoring operation (step S17). The predetermined time is, for example, the time required for sufficient negative pressure to be generated in the brake booster. If the predetermined time has elapsed since the start of the motoring operation, the process proceeds to step S18. If the predetermined time has not elapsed since the start of the motoring operation, the process returns to step S17.

[0053] If a predetermined time has elapsed since the start of motoring operation, the control device 100 instructs the engine 20 to stop motoring operation (step S18). As a result, the engine 20 stops. After this, this process ends.

[0054] If the catalyst temperature in step S3 is not higher than a predetermined temperature Tth, the control device 100 causes the engine 20 to continue motoring (step S19). That is, the control device 100 causes the motor generator 3 to rotate the crankshaft of the engine 20 without injecting fuel into the injectors or generating a spark in the spark plugs.

[0055] Next, the control device 100 determines whether a predetermined time has elapsed since the start of the motoring operation (step S20). If the predetermined time has elapsed since the start of the motoring operation, the process proceeds to step S21. If the predetermined time has not elapsed since the start of the motoring operation, the process returns to step S20.

[0056] If a predetermined time has elapsed since the start of motoring operation, the control device 100 instructs the engine 20 to stop motoring operation (step S21). As a result, the engine 20 stops. After this, this process ends.

[0057] (Other embodiments) The control device according to the present invention is not limited to control device 100, but can be modified within the scope of its gist. Furthermore, the configuration of vehicle 1 and the configuration of vehicle 1a may be combined in any way.

[0058] Alternatively, the control device 100 may estimate the catalyst temperature based on a signal from a temperature sensor provided on the catalyst 18, rather than estimating the catalyst temperature itself.

[0059] Note that the process in step S16 is not mandatory.

[0060] Vehicle 1,1a may be a parallel hybrid vehicle. [Explanation of symbols]

[0061] 1,1a: Vehicle 2: Engine System 3: Motor Generator 4: Inverter 5: Battery 6: Motor 7: Power transmission device 8L: Left front wheel 8R: Right front wheel 10: Vehicles 18: Catalyst 20: Engine 22: Throttle valve 24: Catalyst 26: EGR valve 100: Control device R1: Intake path R2: Exhaust path R3: EGR route

Claims

1. A control device for a vehicle comprising an engine, a motor generator, a motor, and a catalyst, The motor generator generates electricity using the power generated by the engine, The motor generates power to move the vehicle using the electricity generated by the motor generator. The catalyst purifies the exhaust gas flowing out of the engine. In motoring operation, the engine is operated by an external force applied from outside the engine without burning fuel. During firing, the engine is operated by burning fuel. The control device, when performing the motoring operation, stops the motoring operation and performs the firing operation if the temperature of the catalyst is higher than a predetermined temperature. Control device.

2. A control device for a vehicle comprising an engine, a motor generator, a motor, a catalyst, and an EGR valve, The motor generator generates electricity using the power generated by the engine, The motor generates power to move the vehicle using the electricity generated by the motor generator. The engine is connected to an intake path and an exhaust path. The EGR path connects the intake path and the exhaust path. The EGR valve adjusts the amount of exhaust gas flowing from the exhaust path to the intake path. The catalyst is provided in the exhaust path and purifies the exhaust gas flowing out from the engine. In motoring operation, the engine is operated by an external force applied from outside the engine without burning fuel. When the motoring operation is performed when the temperature of the catalyst is higher than a predetermined temperature, the control device controls the EGR valve so that exhaust gas flows from the exhaust path to the intake path. Control device.

3. The aforementioned vehicle further includes a throttle valve, The throttle valve adjusts the amount of air flowing from the intake path into the engine. The control device controls the throttle valve such that when the catalyst temperature is higher than a predetermined temperature and the motoring operation is performed, the opening of the throttle valve is smaller than when the catalyst temperature is lower than a predetermined temperature and the motoring operation is performed. The control device according to claim 2.

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