Treatment method for three-way catalyst, control device for vehicle and control program for vehicle

Abstract

To improve oxygen storage capacity of a three-way catalyst.SOLUTION: A vehicle includes an internal combustion engine and a control device. The internal combustion engine includes: a cylinder for burning fuel; an exhaust passage for causing exhaust gas discharged from the cylinder to flow; a three-way catalyst located in the exhaust passage; a fuel injection valve for supplying the fuel to the cylinder; and a throttle valve for regulating an amount of intake air to be supplied to the cylinder. The three-way catalyst includes: a solid solution containing ceria and zirconia; and rhodium supported by the zirconia. When a temperature predetermined to 850°C or higher is defined as a specified temperature, the control device executes first treatment for supplying gas leaner than that when an air-fuel mixture comprising the fuel and the intake air is burned at a theoretical air-fuel ratio to the three-way catalyst having the specified temperature or higher. After the first treatment, the control device executes second treatment for supplying gas richer than that when the air-fuel mixture is burned at the theoretical air-fuel ratio to the three-way catalyst having the specified temperature or higher.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for treating a three-way catalyst, a vehicle control device, and a vehicle control program. [Background technology]

[0002] The vehicle of Patent Document 1 includes an internal combustion engine and a control device. The control device controls the internal combustion engine. The internal combustion engine includes a cylinder, an exhaust passage, and a three-way catalyst. The cylinder is a space for burning fuel. The exhaust passage is a passage through which exhaust gas discharged from the cylinder flows. The three-way catalyst is located midway through the exhaust passage. The three-way catalyst has the function of purifying exhaust gas and the function of storing oxygen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 061394 Summary of the Invention [Problem to be solved by the invention]

[0004] In an internal combustion engine such as that described in Patent Document 1, the three-way catalyst deteriorates due to sulfur and the like. Therefore, the oxygen storage capacity of the three-way catalyst is relatively high immediately after manufacture. Thereafter, the oxygen storage capacity of the three-way catalyst decreases due to poisoning caused by operation of the internal combustion engine. However, the oxygen storage capacity of the three-way catalyst can also increase or decrease due to reasons other than poisoning. Therefore, there is a demand for a technology that increases the oxygen storage capacity of the three-way catalyst by a process other than the elimination of poisoning. [Means for solving the problem]

[0005] A method for treating a three-way catalyst for solving the above problems is a method for treating a three-way catalyst comprising a solid solution containing ceria and zirconia, and rhodium supported on the zirconia, and includes a first process in which, when a predetermined temperature of 850°C or higher is set as a specified temperature, a gas that is leaner than the gas obtained when a mixture of fuel and intake air is burned at a stoichiometric air-fuel ratio is supplied to the three-way catalyst at a temperature equal to or higher than the specified temperature, and a second process in which, after the first process, a gas that is richer than the gas obtained when the mixture is burned at a stoichiometric air-fuel ratio is supplied to the three-way catalyst at a temperature equal to or higher than the specified temperature.

[0006] A vehicle control device for solving the above problems is a control device applied to a vehicle equipped with an internal combustion engine, the internal combustion engine comprising: a cylinder for burning fuel; an exhaust passage for circulating exhaust gas discharged from the cylinder; a three-way catalyst located in the exhaust passage; a fuel injection valve for supplying fuel to the cylinder; and a throttle valve for adjusting the amount of intake air supplied to the cylinder, the three-way catalyst comprising a solid solution containing ceria and zirconia, and rhodium supported on the zirconia, and when a predetermined temperature that is 850° C. or higher is set as a specified temperature, the three-way catalyst is adapted to control the amount of intake air and the amount of fuel burned by the cylinder; a first process for supplying gas that is leaner than the gas obtained when an air-fuel mixture of air and fuel is burned at the stoichiometric air-fuel ratio to the three-way catalyst at a temperature equal to or higher than the specified temperature; and a second process for supplying gas that is richer than the gas obtained when the air-fuel mixture is burned at the stoichiometric air-fuel ratio to the three-way catalyst at a temperature equal to or higher than the specified temperature after the first process. In the first process, the fuel injection valve and the throttle valve are controlled to achieve a state leaner than the stoichiometric air-fuel ratio, and in the second process, the fuel injection valve and the throttle valve are controlled to achieve a state richer than the stoichiometric air-fuel ratio.

[0007] A vehicle control program for solving the above-mentioned problems is targeted at a control device applied to a vehicle equipped with an internal combustion engine, the internal combustion engine comprising: a cylinder for burning fuel; an exhaust passage for circulating exhaust gas discharged from the cylinder; a three-way catalyst located in the exhaust passage; a fuel injection valve for supplying fuel to the cylinder; and a throttle valve for adjusting the amount of intake air supplied to the cylinder, the three-way catalyst comprising a solid solution containing ceria and zirconia, and rhodium supported on the zirconia, and the control device controls the control device to perform a predetermined control when a predetermined temperature of 850° C. or higher is set as a specified temperature. The system executes a first process of supplying gas that is leaner than the gas obtained when a mixture of fuel and intake air is burned at the theoretical air-fuel ratio to the three-way catalyst at a temperature equal to or higher than the specified temperature, and a second process of supplying gas that is richer than the gas obtained when the mixture is burned at the theoretical air-fuel ratio to the three-way catalyst at a temperature equal to or higher than the specified temperature after the first process.In the first process, the fuel injection valve and the throttle valve are controlled to achieve a state leaner than the theoretical air-fuel ratio, and in the second process, the fuel injection valve and the throttle valve are controlled to achieve a state richer than the theoretical air-fuel ratio. Effect of the Invention

[0008] According to the above configuration, in the first treatment, rhodium supported on zirconia moves to the inside of the zirconia. Then, in the second treatment, the rhodium located inside the zirconia is precipitated on the surface of the zirconia. Furthermore, in the second treatment, a part of the rhodium precipitated on the surface of the zirconia evaporates and moves to the ceria. By this migration of rhodium to the ceria, the oxygen storage capacity of the three-way catalyst can be improved. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a vehicle. [Diagram 2] FIG. 2 is a flowchart showing the determination control. [Diagram 3] FIG. 3 is a flowchart showing the storage amount improvement control. [Figure 4]FIG. 4 is an explanatory diagram showing the three-way catalyst before the first process is executed. [Diagram 5] FIG. 5 is an explanatory diagram showing the three-way catalyst after the first process has been executed. [Figure 6] FIG. 6 is an explanatory diagram showing the three-way catalyst after the second process has been executed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Vehicle Overview> An embodiment of the present invention will now be described with reference to Figures 1 to 6. First, a schematic configuration of a vehicle 100 will be described.

[0011] 1, the vehicle 100 includes a spark ignition internal combustion engine 10. The vehicle 100 also includes a first motor generator 71 and a second motor generator 72 that function as both an electric motor and a generator. Therefore, the vehicle 100 is a so-called hybrid vehicle.

[0012] The internal combustion engine 10 includes a plurality of cylinders 11, a crankshaft 12, an intake passage 21, a throttle valve 22, and a plurality of fuel injectors 23. The internal combustion engine 10 also includes a plurality of ignition devices 24, an exhaust passage 26, a three-way catalyst 27, and a filter 28.

[0013] Each cylinder 11 is a space for burning a mixture of fuel and intake air. The internal combustion engine 10 has four cylinders 11. A crankshaft 12 is connected to a piston (not shown) located in each cylinder 11. The crankshaft 12 rotates by the combustion of the mixture of fuel and intake air in the cylinders 11. In this embodiment, an example of the fuel is gasoline.

[0014] The intake passage 21 is connected to the cylinders 11. A portion of the intake passage 21, including the downstream end, branches into four. Each branched passage is connected to each cylinder 11. The intake passage 21 introduces intake air from outside the internal combustion engine 10 to each cylinder 11. An intake valve (not shown) is located at the connection between the intake passage 21 and each cylinder 11. The intake valve opens and closes the connection between the intake passage 21 and the cylinder 11. The throttle valve 22 is located upstream of the branched portion of the intake passage 21. The throttle valve 22 adjusts the amount of intake air flowing through the intake passage 21.

[0015] The fuel injection valves 23 are located near the downstream end of the intake passage 21. The internal combustion engine 10 is provided with four fuel injection valves 23 corresponding to the four cylinders 11. The fuel injection valves 23 inject fuel supplied from a fuel tank (not shown) into the intake passage 21. As a result, fuel from the fuel injection valves 23 is supplied to the cylinders 11. The ignition devices 24 are located in the cylinders 11. The internal combustion engine 10 is provided with four ignition devices 24 corresponding to the four cylinders 11. The ignition devices 24 ignite a mixture of fuel and intake air by spark discharge.

[0016] The exhaust passage 26 is connected to the cylinders 11. A portion of the exhaust passage 26, including the upstream end, branches into four. Each branched passage is connected to each cylinder 11. The exhaust passage 26 discharges exhaust gas from each cylinder 11 to the outside of the internal combustion engine 10. Note that exhaust valves (not shown) are located at the connections between the exhaust passage 26 and each cylinder 11. The exhaust valves open and close the connections between the exhaust passage 26 and the cylinders 11.

[0017] The three-way catalyst 27 is located downstream of the branched portion of the exhaust passage 26. The three-way catalyst 27 purifies the exhaust gas flowing through the exhaust passage 26. The three-way catalyst 27 includes a solid solution and precious metal particles supported on the solid solution. The solid solution is composed of alumina, ceria, and zirconia. The precious metal particles include platinum, palladium, and rhodium. Therefore, the three-way catalyst 27 has a function of purifying hydrocarbons, carbon monoxide, and nitrogen oxides in the exhaust gas. The three-way catalyst 27 also has a function of storing oxygen in the exhaust gas. In this embodiment, rhodium is supported on the zirconia when the three-way catalyst 27 is manufactured. Note that alumina is also called aluminum oxide. Ceria is also called cerium oxide. Zirconia is also called zirconium dioxide. The filter 28 is located downstream of the three-way catalyst 27 in the exhaust passage 26. The filter 28 collects particulate matter contained in the exhaust gas flowing through the exhaust passage 26 .

[0018] The vehicle 100 includes a first planetary gear mechanism 40, a ring gear shaft 45, a second planetary gear mechanism 50, a reduction mechanism 62, a differential mechanism 63, and a plurality of drive wheels 64. The first planetary gear mechanism 40 includes a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a carrier 44. The sun gear 41 is an external gear. The sun gear 41 is connected to the first motor generator 71. The ring gear 42 is an internal gear and is located coaxially with the sun gear 41. Each pinion gear 43 is located between the sun gear 41 and the ring gear 42. Each pinion gear 43 meshes with both the sun gear 41 and the ring gear 42. The carrier 44 supports the pinion gear 43. The pinion gear 43 is rotatable on its own axis and is revolvable by rotating together with the carrier 44. The carrier 44 is connected to the crankshaft 12. Therefore, the first motor generator 71 is connected to the crankshaft 12 via the first planetary gear mechanism 40.

[0019] The ring gear shaft 45 is connected to the ring gear 42. The ring gear shaft 45 is also connected to drive wheels 64 via a reduction mechanism 62 and a differential mechanism 63. The reduction mechanism 62 reduces the rotation speed of the ring gear shaft 45 and outputs it. The differential mechanism 63 allows a difference in rotation speed to occur between the left and right drive wheels 64.

[0020] The second planetary gear mechanism 50 includes a sun gear 51, a ring gear 52, a plurality of pinion gears 53, a carrier 54, and a case 55. The sun gear 51 is an external gear. The sun gear 51 is connected to the second motor generator 72. The ring gear 52 is an internal gear and is located coaxially with the sun gear 51. The ring gear 52 is connected to the ring gear shaft 45. Each pinion gear 53 is located between the sun gear 51 and the ring gear 52. Each pinion gear 53 meshes with both the sun gear 51 and the ring gear 52. The carrier 54 supports the pinion gear 53. The pinion gear 53 is rotatable. The carrier 54 is fixed to the case 55. Therefore, the pinion gear 53 is not capable of revolving.

[0021] The vehicle 100 includes a battery 75, a first inverter 76, and a second inverter 77. The battery 75 is a secondary battery. The first inverter 76 performs AC-DC power conversion between the first motor generator 71 and the battery 75. The first inverter 76 also adjusts the amount of power exchanged between the first motor generator 71 and the battery 75. The second inverter 77 performs AC-DC power conversion between the second motor generator 72 and the battery 75. The second inverter 77 adjusts the amount of power exchanged between the second motor generator 72 and the battery 75.

[0022] The vehicle 100 is equipped with an air flow meter 81, a water temperature sensor 82, an intake air temperature sensor 83, and a crank angle sensor 84. The vehicle 100 also is equipped with an accelerator operation amount sensor 85, a vehicle speed sensor 86, an upstream air-fuel ratio sensor 87, and a downstream air-fuel ratio sensor 88.

[0023] The air flow meter 81 detects the intake air amount GA, which is the amount of intake air flowing through the intake passage 21 per unit time. The water temperature sensor 82 detects the coolant temperature THW, which is the temperature of the coolant flowing through each part of the internal combustion engine 10. The intake air temperature sensor 83 detects the intake air temperature THA, which is the temperature of the intake air flowing through the intake passage 21. The crank angle sensor 84 detects the crank angle SC, which is the rotational position of the crankshaft 12. The accelerator operation amount sensor 85 detects the accelerator operation amount ACC, which is the amount of operation of the accelerator pedal operated by the driver. The vehicle speed sensor 86 detects the vehicle speed SP, which is the speed of the vehicle 100.

[0024] The upstream air-fuel ratio sensor 87 is located downstream of the branched portion of the exhaust passage 26 and upstream of the three-way catalyst 27. The upstream air-fuel ratio sensor 87 detects an upstream air-fuel ratio AF1, which is the air-fuel ratio of the gas upstream of the three-way catalyst 27 in the exhaust passage 26. The downstream air-fuel ratio sensor 88 is located downstream of the three-way catalyst 27 and upstream of the filter 28 in the exhaust passage 26. The downstream air-fuel ratio sensor 88 detects a downstream air-fuel ratio AF2, which is the air-fuel ratio of the gas downstream of the three-way catalyst 27 in the exhaust passage 26. Here, the air-fuel ratio is a ratio obtained by dividing the mass of air by the mass of fuel. Therefore, the more air relative to the fuel, the higher the air-fuel ratio, that is, the leaner the fuel state becomes. On the other hand, the less air relative to the fuel, the lower the air-fuel ratio, that is, the richer the fuel state becomes. When the internal combustion engine 10 is running, gas from the four cylinders 11 flows continuously into the exhaust passage 26, so the upstream air-fuel ratio AF1 and the downstream air-fuel ratio AF2 become values ​​close to the average values ​​of the air-fuel ratios in the four cylinders 11.

[0025] The vehicle 100 is equipped with a control device 90. The control device 90 obtains a signal indicating the intake air amount GA from the air flow meter 81. The control device 90 obtains a signal indicating the cooling water temperature THW from the water temperature sensor 82. The control device 90 obtains a signal indicating the intake air temperature THA from the intake air temperature sensor 83. The control device 90 obtains a signal indicating the crank angle SC from the crank angle sensor 84. The control device 90 obtains a signal indicating the accelerator operation amount ACC from the accelerator operation amount sensor 85. The control device 90 obtains a signal indicating the vehicle speed SP from the vehicle speed sensor 86. The control device 90 obtains a signal indicating the upstream air-fuel ratio AF1 from the upstream air-fuel ratio sensor 87. The control device 90 obtains a signal indicating the downstream air-fuel ratio AF2 from the downstream air-fuel ratio sensor 88.

[0026] The control device 90 includes an execution unit 91 and a storage unit 92. An example of the execution unit 91 is a CPU. The storage unit 92 includes a read-only ROM, a readable and writable volatile RAM, and a readable and writable non-volatile storage. The storage unit 92 prestores a control program 92A as one of various programs. The execution unit 91 executes the control program 92A to realize various processes described below. Therefore, the execution unit 91 executes the control program 92A to realize various processes related to the treatment method of the three-way catalyst 27.

[0027] The control device 90 calculates a vehicle required driving force, which is a required value of driving force required for the vehicle 100 to travel, based on the accelerator operation amount ACC and the vehicle speed SP. The control device 90 determines the torque distribution of the internal combustion engine 10, the first motor generator 71, and the second motor generator 72 based on the vehicle required driving force. The control device 90 controls the output of the internal combustion engine 10 and the power running and regeneration of the first motor generator 71 and the second motor generator 72 based on the torque distribution of the internal combustion engine 10, the first motor generator 71, and the second motor generator 72. Specifically, the control device 90 controls the opening degree of the throttle valve 22, the fuel injection amount from the fuel injection valve 23, the ignition timing of the ignition device 24, etc., by outputting a control signal to the internal combustion engine 10. The control device 90 also controls the first motor generator 71 via the first inverter 76 by outputting a control signal to the first inverter 76. Furthermore, the control device 90 controls the second motor generator 72 via the second inverter 77 by outputting a control signal to the second inverter 77.

[0028] Furthermore, when the vehicle 100 travels, the control device 90 selects either the EV mode or the HV mode as the travel mode of the vehicle 100. Here, the EV mode is a travel mode in which the vehicle 100 travels by driving one or more motor generators selected from the first motor generator 71 and the second motor generator 72 while stopping the internal combustion engine 10. Therefore, in the EV mode, the vehicle 100 travels by the driving force of the first motor generator 71 and the driving force of the second motor generator 72. Furthermore, the HV mode is a travel mode of the vehicle 100 in which the internal combustion engine 10 is driven in addition to the first motor generator 71 and the second motor generator 72 to travel the vehicle 100. Therefore, in the HV mode, the vehicle 100 travels by the driving force of the internal combustion engine 10 in addition to the driving force of the first motor generator 71 and the second motor generator 72.

[0029] The control device 90 selects the EV mode, for example, when the charging rate of the battery 75 has a sufficient margin and the above-mentioned vehicle required driving force is small. Examples of when the vehicle required driving force is small include when the vehicle 100 starts moving and when the vehicle 100 is running under a light load with low acceleration. On the other hand, the control device 90 selects the HV mode, for example, when the charging rate of the battery 75 does not have a sufficient margin.

[0030] The control device 90 calculates the engine speed NE, which is the number of revolutions per unit time of the crankshaft 12, based on the crank angle SC. The control device 90 also calculates the catalyst temperature TSC, which is the temperature of the three-way catalyst 27, based on the operating conditions of the internal combustion engine 10, such as the intake air charging efficiency and the engine speed NE. The intake air charging efficiency is a value obtained by dividing the mass of intake air actually introduced from the intake passage 21 to the cylinder 11 by the mass of intake air that can be introduced to the cylinder 11 under standard atmospheric conditions.

[0031] The control device 90 calculates the oxygen storage capacity Cmax of the three-way catalyst 27 based on the upstream air-fuel ratio AF1, the downstream air-fuel ratio AF2, the fuel injection amount of the fuel injection valve 23, and the like. For example, the control device 90 calculates the oxygen storage capacity Cmax of the three-way catalyst 27 every time a predetermined specified timing is reached. Here, the oxygen storage capacity Cmax indicates the maximum amount of oxygen that can be stored by the three-way catalyst 27. For example, the control device 90 calculates the oxygen storage capacity Cmax as follows. First, the control device 90 changes the state in which the mixture of fuel and intake air is burned in the cylinder 11 in a state richer than the stoichiometric air-fuel ratio AFS to a state in which the mixture of fuel and intake air is burned in the cylinder 11 in a state leaner than the stoichiometric air-fuel ratio AFS. At this time, the control device 90 calculates the oxygen storage capacity Cmax by integrating the amount of oxygen stored in the three-way catalyst 27 per unit time based on the upstream air-fuel ratio AF1, the downstream air-fuel ratio AF2, and the fuel injection amount of the fuel injection valve 23. The control device 90 also stores the calculated oxygen storage capacity Cmax in the storage unit 92. Note that a technique for calculating the oxygen storage capacity Cmax is also described in, for example, International Publication No. 2013 / 061394.

[0032] <Decision control> Next, the determination control executed by the control device 90 will be described with reference to Fig. 2. In this embodiment, the control device 90 executes the determination control every time it calculates the oxygen storage capacity Cmax.

[0033] 2, when the control device 90 starts the determination control, it executes the process of step S11. In step S11, the control device 90 determines whether the oxygen storage capacity Cmax is equal to or greater than a predetermined reference value ZA. Here, the reference value ZA is a lower limit value of the oxygen storage capacity Cmax that is a minimum required design function of the three-way catalyst 27. The reference value ZA is determined in advance through experiments, simulations, etc.

[0034] In step S11, when the control device 90 determines that the oxygen storage capacity Cmax is equal to or greater than the reference value ZA (S11: YES), the control device 90 advances the process to step S21. In step S21, the control device 90 determines that the oxygen storage capacity Cmax is normal. After step S21, the control device 90 ends the current determination control.

[0035] On the other hand, when the control device 90 determines in step S11 that the oxygen storage capacity Cmax is less than the reference value ZA (S11: NO), the control device 90 advances the process to step S22. In step S22, the control device 90 determines that the oxygen storage capacity Cmax is abnormal. At this time, the control device 90 outputs a control signal to a display (not shown) to display a message on the display to prompt the driver of the vehicle 100, etc., to replace the three-way catalyst 27. After step S22, the control device 90 ends the current determination control.

[0036] <Storage capacity improvement control> Next, the storage amount improvement control executed by the control device 90 will be described with reference to Fig. 3. In this embodiment, the control device 90 starts the update control when the completion flag FA is OFF. Here, the completion flag FA indicates whether or not the improvement of the oxygen storage capacity Cmax by the storage amount improvement control is completed. Note that the completion flag FA is OFF at the time of manufacturing the vehicle 100.

[0037] As shown in FIG. 3, when the control device 90 starts the storage amount improvement control, it executes the process of step S31. In step S31, the control device 90 acquires from the storage unit 92 the oxygen storage capacity Cmax last calculated in a trip before the current trip of the vehicle 100, among the oxygen storage capacities Cmax stored in the storage unit 92. Then, the control device 90 sets a value obtained by adding a predetermined value to the acquired past oxygen storage capacity Cmax as the specified value ZB. Here, the predetermined value is a value that is a certain value smaller than the improvement amount of the oxygen storage capacity Cmax that can be realized by the storage amount improvement control. Note that one trip is a period from when the system of the vehicle 100 is started to when it is ended. After step S31, the control device 90 advances the process to step S32.

[0038] In step S32, the control device 90 acquires the latest oxygen storage capacity Cmax from the storage unit 92 among the oxygen storage capacities Cmax stored in the storage unit 92. Then, the control device 90 determines whether the latest oxygen storage capacity Cmax is equal to or less than the specified value ZB. In step S32, if the control device 90 determines that the latest oxygen storage capacity Cmax is equal to or less than the specified value ZB (S32: YES), the control device 90 proceeds to step S41.

[0039] In step S41, the control device 90 determines whether or not a predetermined first condition is satisfied. Specifically, the control device 90 determines that the first condition is satisfied when the following requirements (1) and (2) are all satisfied.

[0040] Requirement (1): The vehicle 100 is traveling in a predetermined steady state. Requirement (2): The catalyst temperature TSC is equal to or higher than a predetermined start temperature TA. In this embodiment, the control device 90 determines that the requirement (1) is satisfied when the amount of fluctuation in the vehicle required driving force per unit time is equal to or less than a predetermined specified amount of fluctuation. In this embodiment, the start temperature TA is a temperature higher than the activation temperature of the three-way catalyst 27. An example of the start temperature TA is 750° C. In step S41, if the control device 90 determines that the first condition is not satisfied (S41: NO), the control device 90 executes the process of step S41 again. On the other hand, in step S41, if the control device 90 determines that the first condition is satisfied (S41: YES), the control device 90 advances the process to step S42.

[0041] In step S42, the control device 90 determines whether or not a predetermined second condition is satisfied. Specifically, the control device 90 determines that the second condition is satisfied when the following requirements (3) and (4) are all satisfied.

[0042] Requirement (3): The vehicle 100 is traveling in a predetermined steady state. Requirement (4): The catalyst temperature TSC is equal to or higher than a predetermined specified temperature TB. In this embodiment, requirement (3) of step S42 is the same as requirement (1) of step S41. Also, in this embodiment, an example of the specified temperature TB is 850° C. Therefore, the specified temperature TB is a temperature higher than the start temperature TA. If the control device 90 determines in step S42 that the second condition is satisfied (S42: YES), the control device 90 advances the process to step S51.

[0043] In step S51, the control device 90 sets the permission flag FB to ON. Here, the permission flag FB is a flag for permitting the execution of a fuel cut process for stopping the supply of fuel to the cylinder 11. Therefore, the control device 90 executes the fuel cut process when the permission flag FB is ON and a predetermined fuel cut condition is satisfied. In this embodiment, the control device 90 determines that the fuel cut condition is satisfied when the vehicle speed SP is equal to or higher than a predetermined vehicle speed, the accelerator operation amount ACC is zero, and the engine rotation speed NE is equal to or higher than a predetermined rotation speed. Therefore, for example, when the vehicle 100 is traveling downhill or the like and the driver of the vehicle 100 takes his / her foot off the accelerator pedal, the control device 90 determines that the fuel cut condition is satisfied. After step S51, the control device 90 advances the process to step S61.

[0044] In step S61, the control device 90 determines whether or not a predetermined third condition is satisfied. Specifically, the control device 90 determines that the third condition is satisfied when the following requirements (5) and (6) are all satisfied.

[0045] Requirement (5): The catalyst temperature TSC is equal to or higher than a predetermined specified temperature TB. Requirement (6): Fuel cut processing has been performed. In this embodiment, the requirement (5) of step S61 is the same as the requirement (4) of step S42. When the control device 90 determines that the third condition is satisfied in step S61 (S61: YES), the control device 90 ends the current storage amount improvement control. Then, the control device 90 advances the process to step S31 again.

[0046] On the other hand, in step S61, if the control device 90 determines that the third condition is not satisfied (S61: NO), the control device 90 advances the process to step S62. In step S62, the control device 90 determines whether the catalyst temperature TSC is equal to or higher than a predetermined temperature TB. If it is determined in step S62 that the catalyst temperature TSC is equal to or higher than the predetermined temperature TB (S62: YES), the control device 90 advances the process to step S61 again.

[0047] On the other hand, when it is determined in step S62 that the catalyst temperature TSC is lower than the specified temperature TB (S62: NO), the control device 90 advances the process to step S63. In step S63, the control device 90 sets the permission flag FB to OFF. After step S63, the control device 90 advances the process to step S41 again.

[0048] On the other hand, when the control device 90 determines in step S42 that the second condition is not satisfied (S42: NO), the control device 90 advances the process to step S45. In other words, the control device 90 advances the process to step S45, assuming that the catalyst temperature TSC is equal to or higher than the start temperature TA and lower than the specified temperature TB as a necessary condition.

[0049] In step S45, the control device 90 executes an output increase process. Specifically, in the output increase process, the control device 90 increases the output of the internal combustion engine 10 by outputting a control signal to the internal combustion engine 10, compared to when the catalyst temperature TSC is equal to or higher than the specified temperature TB. At this time, the control device 90 increases the output of the internal combustion engine 10 by increasing the torque generated by the internal combustion engine 10 and increasing the engine rotation speed NE, compared to when the catalyst temperature TSC is equal to or higher than the specified temperature TB. Also, in the output increase process, the control device 90 charges the battery 75 with the electric power generated by the first motor generator 71 using the increased output of the internal combustion engine 10. At this time, the control device 90 controls the actual driving force of the vehicle 100 so that it is the same as the vehicle required driving force. In this embodiment, the output increase process in step S45 is a process for increasing the load of the internal combustion engine 10 by charging the battery 75 with the electric power generated by the first motor generator 71 using the output of the internal combustion engine 10. After step S45, the control device 90 advances the process to step S42 again.

[0050] On the other hand, when the control device 90 determines in step S32 that the latest oxygen storage capacity Cmax is greater than the specified value ZB (S32: NO), the control device 90 advances the process to step S71. In other words, when the oxygen storage capacity Cmax has improved as a result of the current storage amount improvement control, the control device 90 advances the process to step S71.

[0051] In step S71, the control device 90 turns on the completion flag FA. When the completion flag FA is turned on in this manner, the storage amount improvement control is not executed after the current storage amount improvement control. After step S71, the control device 90 ends the current storage amount improvement control.

[0052] <First process> As described above, in step S51 of the storage amount improvement control, the control device 90 sets the permission flag FB to ON, with the catalyst temperature TSC being equal to or higher than the specified temperature TB as a necessary condition. Then, when the permission flag FB is ON and a predetermined fuel cut condition is satisfied, the control device 90 executes the fuel cut process. When the fuel cut process is executed in this manner, a gas leaner than the gas obtained when the mixture of fuel and intake air is burned at the stoichiometric air-fuel ratio AFS is supplied to the three-way catalyst 27 via the exhaust passage 26. Therefore, the above process corresponds to a first process in which a gas leaner than the gas obtained when the mixture of fuel and intake air is burned at the stoichiometric air-fuel ratio AFS is supplied to the three-way catalyst 27 at a temperature equal to or higher than the specified temperature TB. Note that, as described above, in the first process, the control device 90 controls the fuel injection valve 23 and the throttle valve 22 to make the mixture leaner than the stoichiometric air-fuel ratio AFS.

[0053] <Second Processing> In the vehicle 100, for example, the catalyst temperature TSC becomes equal to or higher than the specified temperature TB by the above-mentioned storage amount improvement control. Also, for example, the catalyst temperature TSC can become equal to or higher than the specified temperature TB by burning the mixture of fuel and intake air in the cylinder 11 in a control other than the storage amount improvement control. Then, the control device 90 may burn the mixture of fuel and intake air in the cylinder 11 in a state richer than the stoichiometric air-fuel ratio AFS by controlling the fuel injection valve 23 and the throttle valve 22. At this time, gas richer than the gas when the mixture of fuel and intake air is burned at the stoichiometric air-fuel ratio AFS is supplied to the three-way catalyst 27 via the exhaust passage 26. Therefore, the above processing corresponds to a second processing in which gas richer than the gas when the mixture of fuel and intake air is burned at the stoichiometric air-fuel ratio AFS is supplied to the three-way catalyst 27 at the specified temperature TB or higher. Note that, as described above, in the second processing, the control device 90 controls the fuel injection valve 23 and the throttle valve 22 to make the state richer than the stoichiometric air-fuel ratio AFS.

[0054] <Action of this embodiment> As shown in FIG. 4, the three-way catalyst 27 includes a solid solution containing ceria 27C and zirconia 27Z, and rhodium 27R supported on the zirconia 27Z. In addition, in FIG. 4 to FIG. 6, only the ceria 27C, the zirconia 27Z, and the rhodium 27R of the three-way catalyst 27 are shown in a schematic manner. In addition, in FIG. 4 to FIG. 6, some of the ceria 27C, the zirconia 27Z, and the rhodium 27R are marked with reference numerals. As shown in FIG. 3, in the storage amount improvement control, the permission flag FB is set to ON in the vehicle 100, with the catalyst temperature TSC being equal to or higher than the specified temperature TB as a necessary condition. In this manner, in a situation where the permission flag FB is ON, the fuel cut process can be executed in the vehicle 100. Then, for example, when the catalyst temperature TSC is equal to or higher than the specified temperature TB, the control device 90 executes the fuel cut process by controlling the fuel injection valve 23 and the throttle valve 22. Then, a gas leaner than the gas when the mixture of fuel and intake air is burned at the stoichiometric air-fuel ratio AFS is supplied to the three-way catalyst 27 through the exhaust passage 26. That is, a first process is realized in which a gas leaner than the gas when the mixture of fuel and intake air is burned at the stoichiometric air-fuel ratio AFS is supplied to the three-way catalyst 27 at a specified temperature TB or higher. By this first process, as shown in FIG. 5, the rhodium 27R supported on the zirconia 27Z moves to the inside of the zirconia 27Z. After that, for example, when the catalyst temperature TSC is equal to or higher than the specified temperature TB, the control device 90 controls the fuel injection valve 23 and the throttle valve 22 to burn the mixture of fuel and intake air in the cylinder 11 in a state richer than the stoichiometric air-fuel ratio AFS. Then, a gas richer than the gas when the mixture of fuel and intake air is burned at the stoichiometric air-fuel ratio AFS is supplied to the three-way catalyst 27 through the exhaust passage 26. That is, a second process is realized in which a gas richer than the gas obtained when the mixture of fuel and intake air is combusted at the theoretical air-fuel ratio AFS is supplied to the three-way catalyst 27 at a specified temperature TB or higher. This second process causes the rhodium 27R located inside the zirconia 27Z to precipitate on the surface of the zirconia 27Z, as shown in Fig. 6. Furthermore, in the second process, a part of the rhodium 27R precipitated on the surface of the zirconia 27Z evaporates and moves to the surface of the ceria 27C.

[0055] <Effects of this embodiment> (1) According to this embodiment, the rhodium 27R is transferred to the ceria 27C by the first and second treatments. By transferring the rhodium 27R to the ceria 27C in this manner, the oxygen storage capacity Cmax of the three-way catalyst 27 can be improved.

[0056] (2) In the first process, the control device 90 controls the fuel injector 23 and the throttle valve 22 to make the air-fuel ratio leaner than the stoichiometric air-fuel ratio AFS. In the second process, the control device 90 controls the fuel injector 23 and the throttle valve 22 to make the air-fuel ratio richer than the stoichiometric air-fuel ratio AFS. Therefore, for example, the first process and the second process do not need to be performed in the manufacturing process of the three-way catalyst 27. This can simplify the manufacturing process of the three-way catalyst 27 compared to the case where the first process and the second process are performed in the manufacturing process of the three-way catalyst 27.

[0057] (3) In the storage amount improvement control, the control device 90 executes the output increase process of step S45 in the first process and the second process. In this output increase process, the control device 90 increases the load of the internal combustion engine 10 by charging the battery 75 with the electric power generated by the first motor generator 71 using the output of the internal combustion engine 10. Therefore, even when the vehicle required driving force is relatively small, that is, when the load of the internal combustion engine 10 is likely to be relatively small, the load of the internal combustion engine 10 can be increased by consuming the output of the internal combustion engine 10 in the first motor generator 71. When the load of the internal combustion engine 10 is increased, the temperature of the exhaust gas discharged from the cylinder 11 increases, or the amount of exhaust gas discharged from the cylinder 11 increases. This makes it easier for the catalyst temperature TSC to reach or exceed the specified temperature TB. As a result, the number of situations in which the first process and the second process can be executed can be increased.

[0058] (4) If the output increase process of step S45 is executed when the catalyst temperature TSC is less than the start temperature TA, a situation is more likely to occur in which the load on the internal combustion engine 10 becomes excessively large in the output increase process compared to when the catalyst temperature TSC is equal to or higher than the start temperature TA.

[0059] In this regard, in the storage amount improvement control, the control device 90 executes the output increase process of step S45 under the prerequisite that the catalyst temperature TSC is equal to or higher than the start temperature TA and lower than the specified temperature TB. This makes it possible to prevent the load on the internal combustion engine 10 from becoming excessively large in the output increase process of step S45, compared to when the catalyst temperature TSC is lower than the start temperature TA.

[0060] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0061] In the above embodiment, the storage amount improvement control may be modified. For example, the second condition in step S42 may be changed. As a specific example, the specified temperature TB may be a temperature higher than 850°C.

[0062] For example, the condition for executing the output increase process of step S45 may be changed. As a specific example, when the control device 90 determines that the first condition is not satisfied in step S41 (S41: NO), the control device 90 may advance the process to step S45. In other words, the control device 90 may advance the process to step S45 on the condition that the catalyst temperature TSC is lower than the start temperature TA.

[0063] For example, the output increase process of step S45 may be omitted. As a specific example, when the control device 90 determines in step S42 that the second condition is not satisfied (S42: NO), the control device 90 may execute the process of step S42 again. In this case, the vehicle 100 may not be equipped with the first motor generator 71 and the second motor generator 72. In other words, the vehicle 100 may be equipped with only the internal combustion engine 10 as a drive source.

[0064] For example, the manner in which the first process is executed may be changed. As a specific example, the control device 90 may execute the first process by controlling the fuel injector 23 and the throttle valve 22 to combust the mixture of fuel and intake air in the cylinder 11 at a leaner air-fuel ratio than the stoichiometric air-fuel ratio AFS.

[0065] In the above embodiment, the method for treating the three-way catalyst 27 does not have to be executed by the control device 90 of the vehicle 100. For example, in a manufacturing process of the three-way catalyst 27, a control device that controls manufacturing equipment used in the manufacturing process may implement the method for treating the three-way catalyst 27. Also, in a manufacturing process of the three-way catalyst 27, a worker involved in the manufacturing process may implement the method for treating the three-way catalyst 27. Note that a heater or the like that heats the three-way catalyst 27 may be used to raise the catalyst temperature TSC to or above the specified temperature TB. [Explanation of symbols]

[0066] 10...internal combustion engine 11...cylinder 12...crankshaft 21...intake passage 22...throttle valve 23...fuel injector 24...ignition device 26...exhaust passage 27...three-way catalyst 27C...ceria 27R...rhodium 27Z...zirconia 28...filter 40...first planetary gear mechanism 50...second planetary gear mechanism 62...reduction mechanism 63...differential mechanism 64...drive wheels 71...first motor generator 72...second motor generator 75...battery 81...air flow meter 82...water temperature sensor 83...intake air temperature sensor 84...crank angle sensor 85...accelerator operation amount sensor 86...vehicle speed sensor 87...upstream air-fuel ratio sensor 88...downstream air-fuel ratio sensor 90...control device 100...vehicle

Claims

1. 1. A method for treating a three-way catalyst comprising a solid solution containing ceria and zirconia and rhodium supported on the zirconia, comprising the steps of: When a predetermined temperature of 850° C. or higher is set as the specified temperature, a first process of supplying gas that is leaner than the gas obtained when a mixture of fuel and intake air is combusted at a stoichiometric air-fuel ratio to the three-way catalyst having a temperature equal to or higher than the specified temperature; a second process for supplying, after the first process, gas that is richer than the gas obtained when the air-fuel mixture is combusted at a stoichiometric air-fuel ratio to the three-way catalyst having a temperature equal to or higher than the specified temperature; have Method for treating three-way catalyst.

2. A control device applied to a vehicle equipped with an internal combustion engine, the internal combustion engine includes a cylinder that combusts fuel, an exhaust passage through which exhaust gas discharged from the cylinder flows, a three-way catalyst located in the exhaust passage, a fuel injection valve for supplying fuel to the cylinder, and a throttle valve for adjusting the amount of intake air supplied to the cylinder; The three-way catalyst comprises a solid solution containing ceria and zirconia, and rhodium supported on the zirconia; When a predetermined temperature of 850° C. or higher is set as the specified temperature, a first process of supplying gas that is leaner than the gas obtained when a mixture of fuel and intake air is combusted at a stoichiometric air-fuel ratio to the three-way catalyst having a temperature equal to or higher than the specified temperature; a second process for supplying, after the first process, gas that is richer than the gas obtained when the air-fuel mixture is combusted at a stoichiometric air-fuel ratio to the three-way catalyst having a temperature equal to or higher than the specified temperature; It is possible to execute In the first process, the fuel injection valve and the throttle valve are controlled to make the air-fuel ratio leaner than the theoretical air-fuel ratio, In the second process, the fuel injection valve and the throttle valve are controlled to make the air-fuel ratio richer than the theoretical air-fuel ratio. Vehicle control device.

3. The vehicle includes, in addition to the internal combustion engine, a motor generator coupled to a crankshaft of the internal combustion engine, and a battery that can be charged by electric power generated by the motor generator, When one or more of the first process and the second process are executed, the load on the internal combustion engine is increased by charging the battery with electric power generated by the motor generator using an output of the internal combustion engine. The vehicle control device according to claim 2.

4. When a predetermined temperature lower than the specified temperature is set as a start temperature, When performing one or more of the first process and the second process, a necessary condition is that the temperature of the three-way catalyst is equal to or higher than the start temperature and lower than the specified temperature, the load on the internal combustion engine is increased by charging the battery with electric power generated by the motor generator using an output of the internal combustion engine. The vehicle control device according to claim 3.

5. The present invention is directed to a control device applied to a vehicle equipped with an internal combustion engine, the internal combustion engine includes a cylinder that combusts fuel, an exhaust passage through which exhaust gas discharged from the cylinder flows, a three-way catalyst located in the exhaust passage, a fuel injection valve for supplying fuel to the cylinder, and a throttle valve for adjusting the amount of intake air supplied to the cylinder; The three-way catalyst comprises a solid solution containing ceria and zirconia, and rhodium supported on the zirconia; When a predetermined temperature of 850° C. or higher is set as the specified temperature, The control device includes: a first process of supplying gas that is leaner than the gas obtained when a mixture of fuel and intake air is combusted at a stoichiometric air-fuel ratio to the three-way catalyst having a temperature equal to or higher than the specified temperature; a second process for supplying, after the first process, gas that is richer than the gas obtained when the air-fuel mixture is combusted at a stoichiometric air-fuel ratio to the three-way catalyst having a temperature equal to or higher than the specified temperature; Run the command, In the first process, the fuel injection valve and the throttle valve are controlled to make the air-fuel ratio leaner than the theoretical air-fuel ratio, In the second process, the fuel injection valve and the throttle valve are controlled to make the air-fuel ratio richer than the theoretical air-fuel ratio. Vehicle control program.

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