Engine Control Unit

Abstract

The present invention provides an engine control device for quickly recovering a reducing catalyst from sulfur poisoning. The engine control device controls an engine having an occlusion reducing catalyst in an exhaust system and includes a fuel injection control unit that controls the amount of fuel injected by an injector, an EGR control unit that controls an EGR system, a sulfur purification necessity determination unit that determines whether sulfur purification by the occlusion reducing catalyst is necessary, and a sulfur purification control unit that, when sulfur purification is necessary, executes sulfur purification control by injecting fuel so that the occlusion reducing catalyst becomes rich at the inlet and causes the EGR control unit to inhibit EGR. The sulfur purification control unit executes sulfur purification waiting control by injecting fuel so that the occlusion reducing catalyst is concentrated and inhibits EGR when a sulfur purification waiting condition is satisfied. After the sulfur purification waiting control is started, if the sulfur purification waiting condition is no longer satisfied, the sulfur purification control is resumed.

Description

Technical Field

[0001] The present invention relates to an engine control device for controlling an engine having an occlusion reduction catalyst in an exhaust device. Background Art

[0002] For example, an exhaust system of an engine mounted on a vehicle such as an automobile is provided with an exhaust gas after-treatment device for reducing harmful substances in the exhaust gas.

[0003] For example, it is known that in gasoline engines, when the air-fuel ratio is set to be close to the stoichiometric ratio (theoretical air-fuel ratio), NO in exhaust gas can be reduced. X , CO, and HC three-way catalyst.

[0004] Furthermore, it is known that even when the operation is performed at an air-fuel ratio leaner than the activity range of the three-way catalyst, in order to suppress NO X The exhaust device is set to absorb NO X Occlusion reduction catalyst (NO X capture catalyst).

[0005] The occlusion reduction catalyst converts sulfur oxides (SO X ) and NO in exhaust gas X One piece of adsorption, but in SO X In the case of increased sulfur poisoning, the adsorption amount increases, which will lead to NO X The absorption performance deteriorates.

[0006] Therefore, it is known that in an engine having an occlusion reduction catalyst, unburned fuel is supplied as a reducing agent while the temperature in the catalyst layer is raised, thereby reducing SO X Reduction and desorption treatment.

[0007] As a conventional technology related to the regeneration process of the exhaust gas treatment device, for example, Patent Document 1 describes a method for regenerating the exhaust gas from SO2. X Retention agent to remove SO X Before starting to control the reducing agent supply unit, the air-fuel ratio learning value learned when the temperature of the air-fuel ratio detection unit or the exhaust temperature is lower than the predetermined temperature is reset to the initial value. The air-fuel ratio detection unit controls the air-fuel ratio of the internal combustion engine while using the air-fuel ratio learning value learned when it is not poisoned by unburned fuel components.

[0008] Patent Document 2 describes a method for storing NO contained in exhaust gas in an atmosphere with a lean air-fuel ratio. X and absorb NO in the dense atmosphere X Desorbed lean NO XIn the trap (LNT), if the desulfurization suspension condition is satisfied during the execution of the LNT desulfurization mode, the desulfurization of the LNT is suspended and the desulfurization suspension count is accumulated. When the desulfurization is completed, the desulfurization suspension count is reset.

[0009] Patent Document 3 describes a method for removing (S purification) SO2 stored in an occlusion reduction catalyst according to the operating conditions. X In order to reduce the frequency of the condition for the sulfur component to be released, a relationship between the frequency of the state in which the sulfur component is released and the set temperature value for operating the regeneration unit is predefined to obtain a frequency-temperature characteristic, the frequency-temperature characteristic is preliminarily maintained as a plurality of control maps, and the plurality of control maps are switched based on the history of the frequency of the state in which the sulfur component is released within a predetermined period.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-176632

[0013] Patent Document 2: Japanese Patent Application Laid-Open No. 2015-102089

[0014] Patent Document 3: Japanese Patent Application Laid-Open No. 2003-120268 Summary of the Invention

[0015] Technical issues

[0016] When the storage reduction catalyst is performing sulfur purification, execution of the sulfur purification control may be frequently hindered due to a temporary event such as an increase in engine output due to an accelerator operation by a driver.

[0017] In this case, even if the sulfur purification control is resumed after the cause of the interruption is resolved, the catalyst layer must be heated up again to a predetermined temperature range, and recovery of the exhaust gas purification performance takes a long time.

[0018] Furthermore, when sulfur purification is in progress, EGR, which introduces exhaust gas into the intake system, is prohibited due to the increase in temperature of the catalyst layer. However, if the EGR state frequently changes due to the interruption of sulfur purification control, the output torque will fluctuate significantly, which may also cause vehicle vibration.

[0019] Furthermore, since sulfur purification control is accompanied by a deterioration in fuel efficiency, a prolonged time until completion also adversely affects the fuel efficiency of the vehicle.

[0020] In view of the above-mentioned problems, an object of the present invention is to provide an engine control device that allows a reducing catalyst to recover from sulfur poisoning as quickly as possible.

[0021] Technical Solution

[0022] The present invention solves the above-mentioned problems through the following technical solutions.

[0023] According to one embodiment of the present invention, an engine control device is an engine control device for controlling an engine having an occlusion reduction catalyst in an exhaust device, the engine control device comprising: a fuel injection control unit for controlling a fuel injection amount of an injector for injecting fuel into a combustion chamber of the engine; an EGR control unit for controlling an EGR device for introducing exhaust gas from the exhaust device to an intake device of the engine; a sulfur purification necessity determination unit for determining whether sulfur purification by the occlusion reduction catalyst is necessary; and a sulfur purification control unit for executing sulfur purification if it is determined that sulfur purification is necessary. Control, wherein the sulfur purification control causes the fuel injection control unit to inject fuel so that the air-fuel ratio at the inlet of the storage reduction catalyst is rich and causes the EGR control unit to prohibit the introduction of exhaust gas, the sulfur purification control unit executes the sulfur purification waiting control when a predetermined sulfur purification waiting condition is satisfied, and restarts the sulfur purification control when the sulfur purification waiting condition is no longer satisfied after the sulfur purification waiting control is started, the sulfur purification waiting control causing the fuel injection control unit to inject fuel so that the air-fuel ratio is close to the stoichiometric ratio and causing the EGR control unit to prohibit the introduction of exhaust gas.

[0024] Thus, when it becomes difficult to continue the sulfur purification control due to a temporary event during the execution of the sulfur purification control, the sulfur purification standby control in which fuel injection is performed in a manner close to the stoichiometric ratio and EGR is prohibited is executed, and the temperature in the layer of the storage reduction catalyst is prevented from decreasing. Thus, when the sulfur purification control can be restarted, a rich atmosphere can be formed to quickly restore the state of sulfur purification.

[0025] Thereby, the storage reduction catalyst can be recovered from sulfur poisoning at an early stage.

[0026] Furthermore, since sulfur purification control is accompanied by a deterioration in fuel efficiency, the fuel efficiency of the vehicle can be improved by terminating the sulfur purification control as early as possible.

[0027] Furthermore, frequent switching of the EGR switch can be prevented, thereby preventing the occurrence of torque shock.

[0028] In the present invention, the sulfur purification control unit may be configured to cause the fuel injection control unit to perform exhaust stroke injection when the temperature of the storage reduction catalyst is below a predetermined value during the execution of the sulfur purification control, and to stop the exhaust stroke injection during the execution of the sulfur purification waiting control.

[0029] This prevents deterioration of fuel consumption caused by exhaust stroke injection even when sulfur purification is not performed, and also prevents excessive temperature increase of the storage reduction catalyst.

[0030] In the present invention, the sulfur purification control unit may be configured to satisfy the sulfur purification waiting condition when the output demand of the engine is equal to or greater than a predetermined value.

[0031] Thus, the fuel injection control corresponding to the high output request is not hindered by the execution of the sulfur purification control, and the running performance and / or drivability (drivability) of the vehicle can be improved.

[0032] In the present invention, the sulfur purification control unit can be configured to satisfy the sulfur purification waiting condition when at least one of the intake state of the engine, the combustion state of the engine, the temperature state of the engine, the temperature state of the three-way catalyst provided in the exhaust device, the temperature state of the storage reduction catalyst, the canister adsorption state of the fuel vapor treatment device, and the detection state of the sensor provided in the engine temporarily deviates from a predetermined normal state.

[0033] Thus, when sulfur purification is interrupted due to a temporary event with a high possibility of early recovery, the storage reduction catalyst can be appropriately and early recovered from sulfur poisoning by restarting sulfur purification immediately after the event is resolved.

[0034] Effects of the Invention

[0035] As described above, according to the present invention, it is possible to provide an engine control device that allows a reduction catalyst to recover from sulfur poisoning as quickly as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a diagram schematically showing the configuration of an engine having an embodiment of an engine control device to which the present invention is applied.

[0037] Figure 2 1 is a diagram showing a state transition of sulfur purification control of an occlusion reduction catalyst in the engine control device according to the embodiment.

[0038] Explanation of symbols

[0039] 1: Engine

[0040] 10: Crankshaft

[0041] 11: Crankshaft angle sensor

[0042] 20: Cylinder block

[0043] 30: Cylinder head

[0044] 31: Combustion Chamber

[0045] 32: Spark plug

[0046] 33: Air intake

[0047] 34: Exhaust port

[0048] 35: Intake valve

[0049] 36: Exhaust valve

[0050] 37: Intake camshaft

[0051] 38: Exhaust camshaft

[0052] 40: Turbocharger

[0053] 41: Turbine

[0054] 42: Compressor

[0055] 43: Air bypass flow path

[0056] 44: Air bypass valve

[0057] 45: Exhaust gas bypass flow path

[0058] 46: Wastegate valve

[0059] 50: Intake system

[0060] 51: Intake pipe

[0061] 52: Room

[0062] 53: Air filter

[0063] 54: Air flow meter

[0064] 55: Intercooler

[0065] 56: Throttle valve

[0066] 57: Intake manifold

[0067] 58: Intake pressure sensor

[0068] 59: Injector

[0069] 60: Exhaust

[0070] 61: Exhaust manifold

[0071] 62: Exhaust pipe

[0072] 63: Three-way catalyst

[0073] 64: Oscillation reduction catalyst

[0074] 65: Silencer

[0075] 66, 67: Air-fuel ratio sensor

[0076] 70: Can

[0077] 71: Purification pipeline

[0078] 72: Purge control valve

[0079] 73: Purification pipeline

[0080] 74: Purge control valve

[0081] 80: EGR device

[0082] 81: EGR pipeline

[0083] 82: EGR valve

[0084] 83: EGR cooler

[0085] 100: Engine Control Unit (ECU)

[0086] 101: Accelerator pedal sensor DETAILED DESCRIPTION

[0087] Hereinafter, an embodiment of an engine control device to which the present invention is applied will be described.

[0088] The engine control device of the embodiment is a device that centrally controls a horizontally opposed four-cylinder gasoline direct injection turbocharged engine and its auxiliary machines, which is mounted on a vehicle such as a passenger car as a driving power source.

[0089] Figure 1 It is a diagram schematically showing the configuration of an engine including the engine control device according to the embodiment.

[0090] The engine 1 includes a crankshaft 10 , a cylinder block 20 , a cylinder head 30 , a turbocharger 40 , an intake system 50 , an exhaust device 60 , a canister 70 , an EGR device 80 , an engine control unit (ECU) 100 , and the like.

[0091] The crankshaft 10 is a rotating shaft serving as an output shaft of the engine 1 .

[0092] A power transmission mechanism such as a transmission (not shown) is connected to one end portion of the crankshaft 10 .

[0093] A piston is connected to the crankshaft 10 via a connecting rod (not shown).

[0094] A crankshaft angle sensor 11 for detecting the angular position of the crankshaft is provided at the end of the crankshaft 10 .

[0095] The output of the crank angle sensor 11 is transmitted to the ECU 100 .

[0096] The cylinder block 20 is structured in two parts so as to sandwich the crankshaft 10 in the left-right direction when the cylinder block 20 is mounted vertically on the vehicle body.

[0097] The crankshaft 10 is housed in the center of the cylinder block 20 , and a crankcase portion having a main bearing for rotatably supporting the crankshaft 10 is provided.

[0098] Inside the left and right cylinder banks of the cylinder block 20 , which are arranged on both sides of the crankcase portion, there are formed, for example, a pair of cylinders (in the case of four cylinders) in which pistons are inserted and reciprocate.

[0099] The cylinder heads 30 are respectively provided at the ends (left and right ends) of the cylinder block 20 on the opposite side from the crankshaft 10 .

[0100] The cylinder head 30 is configured to include a combustion chamber 31 , a spark plug 32 , an intake port 33 , an exhaust port 34 , an intake valve 35 , an exhaust valve 36 , an intake camshaft 37 , an exhaust camshaft 38 , and the like.

[0101] The combustion chamber 31 is formed by recessing a portion of the cylinder head 30 that faces the piston top surface, for example, in a roof-like shape.

[0102] The spark plug 32 is provided at the center of the combustion chamber 31 and generates a spark in response to an ignition signal from the ECU 100 to ignite the air-fuel mixture.

[0103] The air intake port 33 is a flow path for introducing combustion air (fresh air) into the combustion chamber 31 .

[0104] The exhaust port 34 is a flow path for discharging burned gas (exhaust gas) from the combustion chamber 31 .

[0105] The intake valve 35 and the exhaust valve 36 open and close the intake port 33 and the exhaust port 34 at predetermined valve timings.

[0106] For example, two intake valves 35 and two exhaust valves 36 are provided in each cylinder.

[0107] The intake valve 35 and the exhaust valve 36 are opened and closed by an intake camshaft 37 and an exhaust camshaft 38 that rotate synchronously at half the rotation speed of the crankshaft 10 .

[0108] The cam sprockets of the intake camshaft 37 and the exhaust camshaft 38 are provided with variable valve timing mechanisms (not shown). The variable valve timing mechanisms advance and retard the phases of the camshafts to change the opening and closing timings of the valves.

[0109] The turbocharger 40 is a supercharger that compresses and supercharges combustion air (fresh air) using energy contained in the exhaust gas of the engine 1 .

[0110] The turbocharger 40 includes a turbine 41 , a compressor 42 , an air bypass flow path 43 , an air bypass valve 44 , an exhaust gas bypass flow path 45 , a exhaust gas bypass valve 46 , and the like.

[0111] The turbine 41 is rotationally driven by the exhaust gas of the engine 1 .

[0112] The compressor 42 is coaxially mounted on the turbine 41 and is rotationally driven by the turbine 41 to compress air.

[0113] The air bypass flow path 43 is a flow path that extracts a portion of the air from the downstream side of the compressor 42 and returns the air to the upstream side of the compressor 42 .

[0114] The air bypass valve 44 is provided in the air bypass flow path 43 and switches in two stages between a closed state that substantially closes the air bypass flow path 43 and an open state that allows air to pass through the air bypass flow path 43 in response to a command from the ECU 100 .

[0115] The air bypass valve 44 is an electric valve having a valve body that is driven to open and close by an electric actuator.

[0116] The air bypass valve 44 is set to an open state in order to prevent surge of the turbocharger 40 and / or protect the blades, for example, when the throttle valve 56 is suddenly closed, so that the air in the intake pipe downstream of the compressor 42 flows back to the upstream side of the compressor 42, thereby reducing the residual pressure.

[0117] The exhaust gas bypass flow path 45 is a flow path that extracts a portion of the exhaust gas from the upstream side of the turbine 41 and bypasses it to the downstream side of the turbine 41 for the purpose of supercharging pressure control and / or catalyst temperature increase.

[0118] The exhaust gas bypass flow path 45 is formed integrally with the casing of the turbine 41 .

[0119] The wastegate valve 46 is provided in the wastegate flow path 45 , has a valve body for opening and closing the flow path, and controls the flow rate of the exhaust gas passing through the wastegate flow path 45 .

[0120] The wastegate valve 46 is an electric wastegate valve including an electric actuator that drives a valve body to open and close in response to a command from the ECU 100 .

[0121] The wastegate valve 46 can be switched between a fully open state and a fully closed state, and can also be set to any opening degree at an intermediate position between these states.

[0122] The air intake system 50 is a system that introduces air into the air intake port 33 .

[0123] The intake system 50 includes an intake pipe 51 , a chamber 52 , an air cleaner 53 , an air flow meter 54 , an intercooler 55 , a throttle valve 56 , an intake manifold 57 , an intake pressure sensor 58 , an injector 59 , and the like.

[0124] The intake duct 51 is a flow path that draws in external air and guides it into the intake port 33 .

[0125] The chamber 52 is a space portion provided to communicate with the vicinity of the inlet portion of the intake pipe 51 .

[0126] The air cleaner 53 is provided on the downstream side of the portion of the intake duct 51 communicating with the chamber 52 , and filters the air to remove dust and the like.

[0127] The air flow meter 54 is provided near the outlet of the air cleaner 53 and is a device for measuring the flow rate of air passing through the intake pipe 51 .

[0128] The output of the air flow meter 54 is transmitted to the ECU 100 .

[0129] The compressor 42 of the turbocharger 40 is provided downstream of the air flow meter 54 .

[0130] The intercooler 55 is a heat exchanger provided on the downstream side of the compressor 42 in the intake pipe 51 and cools compressed and high-temperature air by exchanging heat with, for example, traveling air.

[0131] The throttle valve 56 is a butterfly valve provided on the downstream side of the intercooler 55 in the intake pipe 51 , and adjusts the flow rate of air to control the output of the engine 1 .

[0132] The throttle valve 56 is driven to open and close by a throttle valve actuator (not shown) in response to an accelerator pedal operation (not shown) by the driver.

[0133] The throttle valve 56 is provided with a throttle valve sensor for detecting the degree of opening thereof, and the output thereof is transmitted to the ECU 100 .

[0134] The intake manifold 57 is a branch pipe provided on the downstream side of the throttle valve 56 and distributes air to the intake ports 33 of the cylinders.

[0135] The intake pressure sensor 58 is a sensor that detects the pressure of the air in the intake manifold 57 (intake pressure).

[0136] The output of the intake pressure sensor 58 is transmitted to the ECU 100 .

[0137] The injector 59 is provided at the end portion of the intake manifold 57 on the cylinder head 30 side, and is a device that injects fuel into the combustion chamber 31 to form a mixture gas in response to an injection signal instructed by the ECU 100 .

[0138] The exhaust device 60 is a device that discharges the exhaust gas discharged from the exhaust port 34 to the outside.

[0139] The exhaust device 60 is configured to include an exhaust manifold 61 , an exhaust pipe 62 , a three-way catalyst 63 , an occlusion reduction catalyst 64 , a muffler 65 , air-fuel ratio sensors 66 and 67 , and the like.

[0140] The exhaust manifold 61 is a collecting pipe that collects exhaust gas discharged from the exhaust ports 34 of the cylinders.

[0141] The turbine 41 of the turbocharger 40 is arranged on the downstream side of the exhaust manifold 61 .

[0142] The exhaust pipe 62 is a pipe that discharges the exhaust gas discharged from the turbine 41 to the outside.

[0143] The three-way catalyst 63 is provided in the middle portion of the exhaust pipe 62 .

[0144] The three-way catalyst 63 converts HC and NO in the exhaust gas into X , CO and other purification catalysts.

[0145] The three-way catalyst 63 is provided adjacent to the outlet of the turbine 41 .

[0146] The three-way catalyst performs a purification function within a predetermined activity range where the air-fuel ratio is close to the theoretical air-fuel ratio (stoichiometric ratio).

[0147] The storage reduction catalyst 64 is provided in the middle portion of the exhaust pipe 62 and on the downstream side (outlet side) of the three-way catalyst 63 .

[0148] The storage reduction catalyst 64 temporarily stores NO in the exhaust gas when the air-fuel ratio is lean and the engine 1 is running. X , and when the air-fuel ratio is rich, the fuel is used as a reducing agent to reduce NO X Lean NOx X Trapping catalyst (LNT).

[0149] The inlet and outlet of the storage reduction catalyst 64 are provided with a detection device for detecting NO in the exhaust gas. X Concentration of NO (not shown) X sensor.

[0150] The muffler 65 is provided near the outlet of the exhaust pipe 62 and reduces the sound energy of the exhaust gas.

[0151] The air-fuel ratio sensor 66 is provided between the outlet of the turbine 41 and the inlet of the three-way catalyst 63 .

[0152] The air-fuel ratio sensor 67 is provided between the outlet of the three-way catalyst 63 and the inlet of the storage reduction catalyst 64 .

[0153] The air-fuel ratio sensors 66 and 67 are both linear output sensors that detect the amount of oxygen in the exhaust gas by generating an output voltage corresponding to the oxygen concentration in the exhaust gas.

[0154] The outputs of the air-fuel ratio sensors 66 and 67 are both transmitted to the ECU 100 .

[0155] The canister (carbon canister) 70 is a fuel evaporated gas processing device that introduces fuel evaporated gas (vapor) generated in a fuel tank (not shown) storing gasoline used as fuel for the engine 1 and temporarily stores the evaporated gas.

[0156] The canister 70 is configured such that activated carbon capable of temporarily adsorbing fuel evaporated gas is housed in a canister case which is a housing made of resin.

[0157] The tank 70 is configured to include a purge line 71 and a purge control valve 72 mainly used during non-pressurization, and a purge line 73 and a purge control valve 74 mainly used during pressurization.

[0158] The purge line 71 is a flow path having both ends connected to the canister 70 and the intake manifold 57 , respectively, so as to allow the interiors of these to communicate with each other.

[0159] The purge line 71 introduces purge gas consisting of fuel evaporated gas released from the canister 70 into the intake manifold 57 during non-supercharging when the pressure inside the intake manifold 57 is negative.

[0160] The purge control valve (PCV) 72 is a duty-cycle controlled solenoid valve provided midway in the purge line 71 .

[0161] The PCV 72 can be switched between an open state and a closed state and can set the opening degree in the open state in accordance with a command from the ECU 100 .

[0162] The purge line 73 is a flow path having both ends connected to the tank 70 and a region adjacent to the inlet of the compressor 42 of the intake pipe 51 , so that the interiors thereof communicate with each other.

[0163] The purge line 73 is at a positive pressure in the intake manifold 57 . During supercharging, when introduction of the purge gas via the purge line 71 becomes difficult, the purge gas is introduced into the intake pipe 51 upstream of the compressor 42 .

[0164] The purge control valve (PCV) 74 is a solenoid valve provided midway in the purge line 73 .

[0165] The PCV 74 can be switched between an open state and a closed state according to a command from the ECU 100 .

[0166] The EGR device 80 is used to reduce pump loss during part load, reduce cooling loss due to suppression of combustion temperature, and suppress NO X A device that introduces (recirculates) the exhaust gas extracted from the exhaust device 60 into the intake manifold 57 for the purpose of generating, etc.

[0167] The EGR device 80 includes an EGR line, an EGR valve 82 , an EGR cooler 83 , and the like.

[0168] The EGR line 81 is a line that introduces exhaust gas from a part of the exhaust gas flow path into the intake manifold 57 .

[0169] EGR line 81 is Figure 1 In the illustrated example, the exhaust gas is extracted from the exhaust pipe 62 , but the exhaust gas may be extracted from the exhaust manifold 61 and / or the exhaust port 34 .

[0170] The EGR valve 82 can be switched between an open state in which EGR gas (exhaust gas) can flow through the EGR line 81 and a closed state in which the EGR line 81 is closed, according to a command from the ECU 100 , and adjusts the opening degree (exhaust gas flow rate) in the open state.

[0171] The EGR cooler 83 is provided midway in the EGR line 81 and cools the exhaust gas by exchanging heat with, for example, cooling water of the engine 1 and / or running air.

[0172] The engine control unit (ECU) 100 is a unit that centrally controls the engine 1 and its auxiliary machines.

[0173] The ECU 100 is configured to include an information processing unit such as a CPU, a storage unit such as a RAM and / or a ROM, an input / output interface, and a bus connecting these interfaces.

[0174] Furthermore, the ECU 100 is provided with an accelerator pedal sensor 101 that detects the amount of depression of an accelerator pedal (not shown) by the driver.

[0175] The ECU 100 has a function of setting the driver's requested torque based on the output of the accelerator pedal sensor 101 and the like.

[0176] The ECU 100 controls the throttle valve opening, boost pressure, fuel injection amount, ignition timing, valve timing, etc. so that the torque actually generated by the engine 1 approaches the set driver-required torque.

[0177] The ECU 100 functions as a fuel injection control unit that controls the fuel injection amount and fuel injection timing of the injector 59 , and an EGR control unit that controls the EGR device 80 .

[0178] In addition, the ECU 100 has a function to estimate sulfur oxides (SO X ) The amount of adsorption to the storage reduction catalyst 64, the functions of a sulfur purification necessity determination unit for determining whether sulfur purification control described later is necessary, and a sulfur purification control unit for executing sulfur purification control.

[0179] Furthermore, the ECU 100 has a function of executing sulfur purge standby control when the sulfur purge standby condition is satisfied.

[0180] This point will be described in detail below.

[0181] Figure 2 1 is a diagram showing a state transition of sulfur purification control of an occlusion reduction catalyst in the engine control device according to the embodiment.

[0182] like Figure 2 As shown, the control modes of the engine 1 include a normal mode M10 , a sulfur purification mode M20 , and an on-demand sulfur purification mode M30 .

[0183] Furthermore, the sulfur purification mode M20 includes a λ rich sulfur purification mode M21 , a post-injection sulfur purification mode M22 , and a sulfur purification waiting mode M23 .

[0184] When the vehicle starts running, the normal mode M10 is selected.

[0185] In the normal mode M10 , sulfur purification by the storage reduction catalyst 64 is not being performed.

[0186] In the normal mode M10, the stoichiometric combustion in which the average air-fuel ratio in the combustion chamber 31 is close to the stoichiometric air-fuel ratio and the lean combustion in which the fuel is lean relative to the stoichiometric air-fuel ratio are switched appropriately according to the operating state (required torque, rotation speed, etc.).

[0187] The ECU 100 has a function of estimating the sulfur poisoning amount (SO) of the storage reduction catalyst 64 based on, for example, the past operating state history of the engine 1. X function of the adsorption capacity).

[0188] In the normal mode M10, when the engine 1 is in the stoichiometric combustion process, if the estimated sulfur poisoning amount (temporary poisoning amount) is equal to or greater than a predetermined threshold value and the transition inhibition condition for inhibiting transition to the sulfur purification mode M20 is not satisfied, transition to the sulfur purification mode M20 is performed.

[0189] The transition inhibition condition for inhibiting transition to the sulfur purification mode M20 is, for example, that at least one of the following conditions is satisfied.

[0190] The vehicle speed is at the predetermined high speed

[0191] The vehicle's remaining fuel level is below a predetermined value.

[0192] The amount of permanent poisoning that cannot be purified exceeds the predetermined value (a state where the required purification rate cannot be achieved even with sulfur purification)

[0193] The cooling water temperature of engine 1 is lower than the predetermined value

[0194] The variable valve timing mechanism is not in operation

[0195] Initial learning of intake pressure sensor 58 is not completed

[0196] Air-fuel ratio learning is not completed

[0197] Air-fuel ratio sensor, NO X The sensor is inactive

[0198] Catalyst preheating or heating requirements are above the predetermined

[0199] The intake air temperature exceeds the upper limit of the predetermined temperature range (high intake air temperature) or is lower than the lower limit of the predetermined temperature range (low intake air temperature)

[0200] Atmospheric pressure is lower than the preset lower limit

[0201] · Injection quantity characteristic learning (Q min Learning) not completed

[0202] On the other hand, when the sulfur purification mode M20 is selected, the mode returns to the normal mode M10 when the sulfur purification is completed (the sulfur poisoning amount is equal to or less than a predetermined purification completion threshold) or when a predetermined sulfur purification prohibition condition is satisfied.

[0203] Examples of the sulfur purge prohibition condition include a case where a misfire is determined, or a case where a fail-safe flag indicating a failure in hardware or software such as a sensor is set.

[0204] The lambda rich sulfur purification mode M21 is a control mode for executing sulfur purification when, for example, the operating state of the engine 1 is a predetermined high load state (for example, the output torque and the rotation speed are both above predetermined values) and the storage reduction catalyst 64 is heated to a temperature range capable of sulfur purification.

[0205] In the λ rich sulfur purification mode M21, the air-fuel ratio A / F (which can be expressed by the excess air coefficient λ) of the engine 1 is made rich, fuel is supplied as a reducing agent to the high-temperature storage reduction catalyst 64, and SO stored in the storage reduction catalyst 64 is reduced. X Perform purification (desorption) treatment.

[0206] At this time, in order to suppress a drop in the exhaust gas temperature, the EGR valve 82 is fixed to the closed state, and EGR is prohibited.

[0207] The post-injection sulfur purification mode M22 is a control mode for executing sulfur purification when, for example, the operating state of the engine 1 is a predetermined medium load state (for example, the output torque and the rotational speed are each within a predetermined range lower than that of the high load state) and the temperature of the storage reduction catalyst 64 is raised to a temperature range capable of sulfur purification by performing post-injection.

[0208] The post-injection sulfur purification mode M22 supplies unburned fuel to the exhaust device 60 by performing post injection during the exhaust stroke while setting the air-fuel ratio in the combustion chamber 31 at the time of ignition of the engine 1 to a fuel-low ratio.

[0209] A portion of the unburned fuel supplied to the exhaust device 60 is burned by the three-way catalyst 63 to raise the temperature of the exhaust gas, and is used to heat the storage reduction catalyst 64. The other portion of the unburned fuel is supplied to the storage reduction catalyst 64 as a reducing agent.

[0210] At this time, the EGR valve 82 is fixed in the closed state, and EGR is prohibited.

[0211] In a state where the lambda rich sulfur purification mode M21 is selected, when the load state of the engine 1 changes from a high load state to a medium load state, the mode transitions to the post injection sulfur purification mode M22 .

[0212] When the load state of the engine 1 changes from the medium load state to the high load state in the state where the post-injection sulfur purification mode M22 is selected, the mode transitions to the lambda rich sulfur purification mode M21 .

[0213] Furthermore, when the lambda rich sulfur purge mode M21 or the post-injection sulfur purge mode M22 is selected, if a predetermined sulfur purge waiting condition is satisfied, the sulfur purge waiting mode M23 is selected.

[0214] The sulfur purification waiting mode M23 is a control mode for maintaining the temperature within the layer of the storage reduction catalyst 64 so that, when sulfur purification is interrupted due to a temporary event, sulfur purification can be resumed immediately after the event is resolved.

[0215] In the sulfur purification waiting mode M23 , the engine 1 is operated in the stoichiometric combustion state, and the EGR valve 82 is set to the closed state.

[0216] The sulfur purification waiting condition for making a transition to the sulfur purification waiting mode M23 is, for example, that at least one of the following conditions is satisfied.

[0217] The required torque due to the driver's accelerator operation is greater than a predetermined value.

[0218] The vehicle speed is below the predetermined value

[0219] The transmission is in a non-driving gear (such as P or N).

[0220] · If the steam exceeds the capacity of the tank 70, the steam may escape into the atmosphere.

[0221] The estimated temperature within the layer of the three-way catalyst 63 exceeds a predetermined upper limit.

[0222] The estimated temperature within the storage reduction catalyst 64 exceeds a predetermined upper limit.

[0223] The estimated temperature within the three-way catalyst layer 63 is lower than a predetermined lower limit.

[0224] There is an ignition time delay requirement

[0225] · To avoid pre-ignition, etc., there is a demand for a richer air-fuel ratio

[0226] In addition, when a predetermined operation input is performed, for example, due to an inspection at a maintenance site, the sulfur purification waiting condition can be partially relaxed.

[0227] For example, the mode may be configured not to transition to the sulfur purification standby mode M23 even when the vehicle speed is equal to or lower than a predetermined value or when a non-driving gear is selected.

[0228] Furthermore, in order to prevent hunting, the predetermined values, upper limit values, lower limit values, and the like may be configured to provide a hysteresis between transitioning to the sulfur purification standby mode M23 and returning to the original mode from the sulfur purification standby mode M23.

[0229] When the sulfur purification waiting mode M23 is selected, if the sulfur purification waiting condition is no longer satisfied, the engine 1 is in a high load state, and the storage reduction catalyst 64 has been heated to a state capable of sulfur purification, the mode shifts to the lambda rich sulfur purification mode M21.

[0230] When the sulfur purification waiting mode M23 is selected, if the sulfur purification waiting condition is no longer satisfied, the engine 1 is in a medium load state, and the storage reduction catalyst 64 can be heated to a state capable of sulfur purification by post injection, the mode is shifted to the post injection sulfur purification mode M22.

[0231] Furthermore, in the sulfur purge mode M20, which includes the lambda rich sulfur purge mode M21, the post-injection sulfur purge mode M22, and the sulfur purge standby mode M23, if sulfur purge is not completed after a predetermined upper limit time has elapsed, which depends on, for example, the vehicle's driving mode, the driver's driving mode, etc., an interruption determination is made for the sulfur purge in that driving mode in order to suppress fuel consumption.

[0232] In the state where the sulfur purification mode M20 is selected, when the sulfur purification is completed or when the above-mentioned prohibition condition or interruption determination is satisfied, the mode transitions to the normal mode M10.

[0233] Furthermore, even when the amount of sulfur poisoning of the storage reduction catalyst 64 is less than the aforementioned threshold value, the ECU 100 has a function of executing an on-demand sulfur purification mode M30 in which sulfur purification is performed on an on-demand basis, using the same control as in the lambda rich sulfur purification mode M21, when the storage reduction catalyst 64 is heated to a state capable of sulfur purification and the engine 1 is in a high load state.

[0234] According to the present embodiment described above, the following effects can be obtained.

[0235] (1) During the execution of the λ rich sulfur purge mode M21 or the post-injection sulfur purge mode M22, if it becomes difficult to continue the sulfur purge control due to a temporary event, the sulfur purge standby mode M23 is executed in which fuel injection is performed in a manner close to the stoichiometric ratio and EGR is prohibited, thereby preventing the temperature in the layer of the storage reduction catalyst 64 from decreasing. When the sulfur purge control can be resumed, the mode is restored to the λ rich sulfur purge mode M21 or the post-injection sulfur purge mode M22, thereby enabling the sulfur purge to be quickly restored.

[0236] Thereby, the storage reduction catalyst 64 can be recovered from sulfur poisoning at an early stage.

[0237] (2) By stopping the post injection when transitioning from the post injection sulfur purification mode M22 to the sulfur purification waiting mode M23 , it is possible to prevent deterioration of fuel consumption caused by performing post injection even when sulfur purification is not being performed, and to prevent excessive temperature rise of the storage reduction catalyst 64 .

[0238] (3) By transitioning to the sulfur purge standby mode M23 when the required torque of the engine 1 is equal to or greater than a predetermined value, the fuel injection control corresponding to the high output demand is not hindered by the execution of the lambda rich sulfur purge mode M21 or the post-injection sulfur purge mode M22, thereby improving the vehicle's running performance and / or drivability (drivability).

[0239] (4) When at least one of the intake state, combustion state, temperature state of the engine 1, temperature state of the three-way catalyst 63 and the storage reduction catalyst 64, adsorption state of the tank 70, and detection state of various sensors temporarily deviates from the predetermined normal state, by making a transition to the sulfur purification waiting mode M23, it is possible to restart sulfur purification immediately after eliminating a temporary event with a high possibility of early recovery when sulfur purification is interrupted, and to restore the storage reduction catalyst 64 from sulfur poisoning as early as possible.

[0240] (Variation)

[0241] The present invention is not limited to the above-described embodiment, and various modifications and / or changes are possible, and these modifications and / or changes are also within the technical scope of the present invention.

[0242] (1) The configurations of the engine control device and the engine are not limited to the above-described embodiment, and can be modified as appropriate.

[0243] For example, the cylinder layout of the engine, the number of cylinders, the presence or absence of a supercharger, the arrangement of catalysts and / or sensors, etc. can be changed as appropriate.

[0244] (2) In the embodiment, the conditions for transitioning to each control mode are given as examples and can be appropriately changed, added, or omitted. Furthermore, the specific control content in each control mode is not particularly limited.

Claims

1. An engine control device, characterized in that: An engine control device is provided for controlling an engine having an occlusion reduction catalyst in an exhaust device. The engine control device includes: a fuel injection control unit that controls a fuel injection amount of an injector that injects fuel into a combustion chamber of the engine; an EGR control unit that controls an EGR device that introduces exhaust gas from the exhaust device to the intake device of the engine; a sulfur purification necessity determination unit that determines whether sulfur purification of the storage reduction catalyst is necessary; and a sulfur purification control unit that, when it is determined that the sulfur purification is necessary, executes sulfur purification control, wherein the sulfur purification control causes the fuel injection control unit to inject fuel so that the air-fuel ratio at the inlet of the storage reduction catalyst becomes rich and causes the EGR control unit to prohibit the introduction of exhaust gas; The sulfur purification control unit executes sulfur purification waiting control when a predetermined sulfur purification waiting condition is satisfied, and restarts the sulfur purification waiting control when the sulfur purification waiting condition is no longer satisfied after the sulfur purification waiting control is started. The sulfur purification waiting control causes the fuel injection control unit to inject fuel at a ratio close to the stoichiometric ratio and causes the EGR control unit to prohibit the introduction of exhaust gas.

2. The engine control device according to claim 1, characterized in that: The sulfur purification control unit causes the fuel injection control unit to perform exhaust stroke injection when the temperature of the storage reduction catalyst is equal to or lower than a predetermined value during the execution of the sulfur purification control, and stops the exhaust stroke injection during the execution of the sulfur purification waiting control.

3. The engine control device according to claim 1 or 2, characterized in that: The sulfur purification control unit satisfies the sulfur purification waiting condition when the output demand of the engine is equal to or greater than a predetermined value.

4. The engine control device according to claim 1 or 2, characterized in that: The sulfur purification control unit satisfies the sulfur purification waiting condition when at least one of an intake state of the engine, a combustion state of the engine, a temperature state of the engine, a temperature state of a three-way catalyst provided in the exhaust device, a temperature state of the storage reduction catalyst, an adsorption state of a canister of a fuel vapor treatment device, and a detection state of a sensor provided in the engine temporarily deviates from a predetermined normal state.

5. The engine control device according to claim 3, characterized in that: The sulfur purification control unit satisfies the sulfur purification waiting condition when at least one of an intake state of the engine, a combustion state of the engine, a temperature state of the engine, a temperature state of a three-way catalyst provided in the exhaust device, a temperature state of the storage reduction catalyst, an adsorption state of a canister of a fuel vapor treatment device, and a detection state of a sensor provided in the engine temporarily deviates from a predetermined normal state.

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