JP6966910B2 - Engine control unit - Google Patents

Description

The present invention relates to an engine control device that controls an engine.

A catalyst for purifying regulated substances such as hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) is provided in the exhaust flow path of the vehicle. However, the catalyst is permanently poisoned by poisonous substances such as phosphorus (P) in the engine oil mixed in the exhaust gas.

Therefore, as a technique for enhancing the poisoning resistance to phosphorus, a technique for incorporating barium (Ba), strontium (Sr), and magnesium (Mg) into the catalyst (for example, Patent Document 1) is disclosed.

Japanese Unexamined Patent Publication No. 2003-47848

However, depending on the operating condition of the engine, the amount of engine oil mixed in the exhaust gas may be larger than expected, and the amount of poisoning of the catalyst may exceed the design value. In this case, the purification performance of the catalyst may not be maintained.

Therefore, an object of the present invention is to provide an engine control device capable of maintaining the purification performance of the catalyst.

In order to solve the above problems, the engine control device of the present invention has a poisoning amount deriving unit that derives the poisoning amount of the catalyst by the poisonous substance contained in the exhaust gas, and the poisoning amount every predetermined traveling period. The poisoning amount determination unit that determines whether or not the amount is equal to or more than a predetermined threshold, and when it is determined that the poisoning amount is equal to or greater than the threshold value, the exhaust is discharged from the engine in the next running period. A control processing execution unit that executes a processing for suppressing the mixing of the poisonous substance into the gas is provided , the poisonous substance is contained in the engine oil, and the poisoning amount derivation unit uses the catalyst. the amount of engine oil that passes through, and, on the basis of the poisoning rate of the catalyst due to poisoning substances, it derives the poisoning amount.

Further, the poisoned amount deriving unit may derive the amount of engine oil passing through the catalyst based on the engine load and the engine rotation speed.

Further, the poisoning amount derivation unit may derive the poisoning rate of the catalyst by the poisoning substance based on the temperature of the exhaust gas and the flow velocity of the exhaust gas.

Further, the process of suppressing the mixing of the toxic substance into the exhaust gas is a process of controlling the throttle opening when cutting the supply of fuel to the engine, and a process of controlling the engine speed. Either one or both may be used.

According to the present invention, it is possible to maintain the purification performance of the catalyst.

It is a schematic diagram which shows the structure of an engine control device. It is a flowchart explaining the flow of an engine control process.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in the embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and the drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate explanations, and elements not directly related to the present invention are not shown. do.

FIG. 1 is a schematic view showing the configuration of the engine control device 1. However, in the following, the configurations and processes related to the present embodiment will be described in detail, and the description of the configurations and processes unrelated to the present embodiment will be omitted.

As shown in FIG. 1, the engine control device 1 is provided with an engine 2 and an ECU 3 (Engine Control Unit), and the entire engine 2 is driven and controlled by the ECU 3. The engine 2 is provided with a cylinder block 10, a crankcase 12 integrally formed with the cylinder block 10, and a cylinder head 14 connected to the cylinder block 10.

A plurality of cylinders 16 are formed in the cylinder block 10, and a piston 18 is slidably supported by the connecting rod 20 in the cylinder 16. Then, a space surrounded by the cylinder head 14, the cylinder 16, and the crown surface of the piston 18 is formed as the combustion chamber 22.

Further, in the engine 2, a crankcase 24 is formed by a crankcase 12, and a crankshaft 26 is rotatably supported in the crankcase 24. A piston 18 is connected to the crankshaft 26 via a connecting rod 20.

The cylinder head 14 is formed so that the intake port 28 and the exhaust port 30 communicate with the combustion chamber 22.

An intake flow path 34 including an intake manifold 32 is connected to the intake port 28. The intake port 28 has one opening on the upstream side of the intake air facing the intake manifold 32 and two openings on the downstream side facing the combustion chamber 22, and the flow path is on the way from the upstream to the downstream. Is branched into two. The tip of the intake valve 36 is located between the intake port 28 and the combustion chamber 22, and the intake valve 36 opens and closes the intake port 28 with respect to the combustion chamber 22 as the camshaft (not shown) rotates.

An exhaust flow path 40 including an exhaust manifold 38 is connected to the exhaust port 30. The exhaust port 30 has two openings on the upstream side of the exhaust facing the combustion chamber 22 and one opening on the downstream side facing the exhaust manifold 38, and the flow path is on the way from the upstream to the downstream. Are integrated into one. The tip of the exhaust valve 42 is located between the exhaust port 30 and the combustion chamber 22, and the exhaust valve 42 opens and closes the exhaust port 30 with respect to the combustion chamber 22 as the camshaft (not shown) rotates.

Further, the cylinder head 14 is provided with an injector 44 and a spark plug 46 so that the tip thereof is located in the combustion chamber 22, and the injector 44 receives air flowing into the combustion chamber 22 through the intake port 28. Fuel is injected. Then, the air-fuel mixture is ignited by the spark plug 46 at a predetermined timing and burned. Due to such combustion, the piston 18 reciprocates in the cylinder 16, and the reciprocating motion is converted into the rotational motion of the crankshaft 26 through the connecting rod 20.

The intake flow path 34 is provided with an air cleaner 48 and a throttle valve 50 in this order from the upstream side. The air cleaner 48 removes foreign matter mixed with the air sucked from the outside air. The throttle valve 50 is driven to open and close by the actuator 52 according to the opening degree of the accelerator (not shown), and adjusts the amount of air sent to the combustion chamber 22.

A catalyst 60 is provided in the exhaust flow path 40. The catalyst 60 is, for example, a three-way catalyst, which is composed of platinum (Pt), palladium (Pd), and rhodium (Rh), and is contained in the exhaust gas discharged from the combustion chamber 22. Purifies (removes) regulated substances (hydrogen (HC), carbon monoxide (CO), nitrogen oxides (NOx)).

Further, the engine control device 1 is provided with an accelerator opening degree sensor 70, a throttle opening degree sensor 72, a crank angle sensor 74, a flow meter 76, and an exhaust temperature sensor 78.

The accelerator opening sensor 70 detects the amount of depression of the accelerator pedal. The throttle opening sensor 72 detects the opening degree (engine load) of the throttle valve 50. The crank angle sensor 74 is provided in the vicinity of the crankshaft 26, and outputs a pulse signal each time the crankshaft 26 rotates by a predetermined angle. The flow meter 76 is provided downstream of the throttle valve 50 in the intake flow path 34, and detects the amount of air that passes through the throttle valve 50 and is supplied to the combustion chamber 22. The exhaust temperature sensor 78 detects the temperature of the exhaust gas in the exhaust flow path 40.

The ECU 3 is a microcomputer including a central processing unit (CPU), a ROM in which a program or the like is stored, a RAM as a work area, and the like, and controls the engine 2 in an integrated manner. In the present embodiment, the ECU 3 functions as a drive control unit 110, a poisoned amount derivation unit 112, and a poisoned amount determination unit 114 when executing the engine control process.

The drive control unit 110 derives the current engine speed based on the pulse signal detected by the crank angle sensor 74, and based on the derived engine speed and the accelerator opening detected by the accelerator opening sensor 70. , The target torque and the target engine speed are derived by referring to the target map stored in advance.

Further, the drive control unit 110 determines the target air amount to be supplied to each cylinder 16 based on the derived target engine speed and target torque, and determines the target throttle opening degree based on the determined target air amount. .. Then, the drive control unit 110 drives the actuator 52 so that the throttle valve 50 opens at the determined target throttle opening degree.

Further, the drive control unit 110 determines, for example, a fuel amount having a theoretical air-fuel ratio (λ = 1) as a target injection amount based on the determined target air amount, and takes in the fuel of the determined target injection amount from the piston 18. The target injection timing and target injection period of the injector 44 are determined in order to inject from the injector 44 in the stroke or compression stroke. Then, the drive control unit 110 drives the injector 44 at the determined target injection timing and target injection period to inject the fuel of the target injection amount from the injector 44.

Further, the drive control unit 110 determines the target ignition timing of the spark plug 46 based on the derived target engine speed and the pulse signal detected by the crank angle sensor 74. Then, the drive control unit 110 ignites the spark plug 46 at the determined target ignition timing.

By the way, engine oil is supplied as lubricating oil to each component of the engine 2 such as the piston 18, the connecting rod 20, and the crankshaft 26. The combustion chamber 22 becomes a negative pressure when the piston 18 moves toward the bottom dead center. At this time, the engine oil enters the combustion chamber 22 through the gap (clearance) formed between the cylinder block 10 and the piston 18, and is mixed with the exhaust gas. Toxic substances such as phosphorus contained in engine oil permanently poison the catalyst 60.

Therefore, it is conceivable to adopt a catalyst 60 having enhanced resistance to poisoning with phosphorus. However, depending on the operating state of the engine 2, the amount of engine oil mixed in the exhaust gas may be larger than expected, and the amount of poisoning of the catalyst 60 may exceed the design value. There is no problem when the poisoning amount of the catalyst 60 is less than the design value, but if the poisoning amount exceeds the design value, the purification performance of the catalyst 60 may not be maintained.

Further, it is conceivable to reduce the clearance by increasing the tension of the piston ring provided on the outer periphery of the piston 18 and reduce the amount of engine oil entering the combustion chamber 22. However, if the tension of the piston ring is increased, the friction between the piston 18 (piston ring) and the cylinder 16 increases, and the fuel consumption deteriorates.

Therefore, in the present embodiment, the poisoning amount derivation unit 112 derives the poisoning amount of the catalyst 60 by the poisoning substance, and the poisoning amount determination unit 114 determines the poisoning amount for each predetermined traveling period. Determine if it is greater than or equal to the threshold. When the poisoning amount is equal to or higher than the threshold value, the drive control unit 110 functioning as the control process execution unit executes a predetermined control process, so that the catalyst 60 is poisoned without increasing the tension of the piston ring. Keep the amount below the design value. Hereinafter, the specific configuration of the poisoning amount derivation unit 112, the poisoning amount determination unit 114, and the drive control unit 110 functioning as the control processing execution unit will be described in detail.

The poisoning amount derivation unit 112 derives the poisoning amount of the catalyst 60 by the poisonous substance contained in the exhaust gas. Specifically, the poisoning amount derivation unit 112 determines the amount of engine oil passing through the catalyst 60 (hereinafter referred to as "the amount of passing engine oil") and the poisoning rate of the catalyst 60 by the poisoning substance. Based on this, the poisoning amount of the catalyst 60 is derived. Hereinafter, the passage amount derivation process for deriving the passage amount of the engine oil, the poisoning rate derivation process for deriving the poisoning rate, and the poisoning amount derivation process for deriving the poisoning amount will be described in detail.

(Passage derivation process)
The poisoned amount derivation unit 112 refers to a passing amount map stored in advance in a memory (not shown) based on the engine speed derived by the drive control unit 110 and the engine load detected by the throttle opening sensor 72. , The current amount of engine oil passing through, and the current flow rate of exhaust gas passing through the catalyst 60, respectively.

The passing amount map is created based on the actually measured values, and is a map in which the passing amount of engine oil and the flow rate of exhaust gas are associated with the engine speed and the engine load. In the passing amount map, the larger the engine speed, the larger the passing amount of the engine oil, and the larger the engine load, the smaller the passing amount of the engine oil.

(Poisoning rate derivation process)
The poisoning amount derivation unit 112 first derives the current flow rate of the exhaust gas based on the flow rate of the exhaust gas derived in the passage amount derivation process and the flow path cross-sectional area of the exhaust flow path 40. Then, the poisoning amount derivation unit 112 refers to a poisoning rate map stored in advance in a memory (not shown) based on the temperature of the exhaust gas detected by the exhaust temperature sensor 78 and the flow velocity of the derived exhaust gas. , Derive the current poisoning rate.

The poisoning rate map is created based on the measured values, and is a map in which the poisoning rate is associated with the temperature of the exhaust gas and the flow velocity of the exhaust gas. In the poisoning rate map, the higher the temperature of the exhaust gas, the higher the poisoning rate, and the lower the flow velocity of the exhaust gas, the higher the poisoning rate.

(Toxic amount derivation process)
The poisoning amount derivation unit 112 multiplies the current passing amount of the engine oil derived by the passing amount derivation process with the current poisoning rate derived by the poisoning rate derivation process, and then multiplies the current poisoning rate (unit time). The amount of poisoning of the catalyst 60 is derived. Then, the poisoned amount derivation unit 112 adds the current poisoned amount of the catalyst 60 to the integrated value of the poisoned amount of the catalyst 60 up to the previous time. In this way, the poisoning amount of the catalyst 60 is derived.

The poisoning amount determination unit 114 determines whether or not the poisoning amount of the catalyst 60 is equal to or higher than a predetermined threshold value for each predetermined traveling period (driving cycle: for example, a period during which the traveling distance is 10,000 km). .. More specifically, the poisoning amount determination unit 114 determines whether or not the poisoning amount of the catalyst 60 is equal to or higher than a predetermined threshold value at each end of the driving cycle. Here, the threshold value Th is represented by the following equation (1).
Threshold Th = {K × (DR / SS)} × n… Equation (1)
In the formula (1), K indicates a predetermined allowable value of the poisoning amount of the catalyst 60 after a predetermined maximum assumed traveling period (for example, a period in which the traveling distance is 240,000 km) has elapsed. DR indicates the mileage of the driving cycle. SS indicates the mileage of the maximum assumed running period. n indicates the number of current driving cycles. The permissible value K of the poisoning amount of the catalyst 60 is the maximum value of the poisoning amount capable of maintaining the purification performance in which the concentration of the regulated substance in the exhaust gas passing through the catalyst 60 is less than the regulated value.

When the poisoning amount determination unit 114 determines that the poisoning amount is equal to or higher than the threshold value, the drive control unit 110 causes the engine 2 to mix the poisonous substance into the exhaust gas in the next driving cycle. The suppression process (hereinafter referred to as "mixture suppression process") is executed.

Specifically, the drive control unit 110 controls the actuator 52 when cutting the fuel supply to the engine 2 (for example, during deceleration) as a mixing suppression process to increase the opening degree of the throttle valve 50. Execute the process to be performed. As a result, the pressure in the combustion chamber 22 can be increased (the degree of negative pressure can be decreased), and the amount of engine oil entering the combustion chamber 22 from the crankcase 12 can be reduced. At this time, the drive control unit 110 adjusts the opening degree of the throttle valve 50 within a range in which the target deceleration can be maintained.

Further, the drive control unit 110 executes a process of reducing the engine speed as a process of suppressing mixing. As a result, the number of times the piston 18 slides on the cylinder block 10 (the number of times the piston 18 reciprocates in the cylinder 16) can be reduced, and the amount of engine oil entering the combustion chamber 22 from the crankcase 12 can be reduced. Is possible.

(Engine control processing)
Subsequently, the engine control process by the drive control unit 110, the poison amount derivation unit 112, and the poison amount determination unit 114 that function as the control process execution unit will be described. FIG. 2 is a flowchart illustrating a flow of engine control processing. Further, in the present embodiment, the engine control process is repeatedly executed by the interruption that occurs at predetermined time intervals.

(Step S110)
The poisoned amount derivation unit 112 executes the above-mentioned passing amount derivation process to derive the passing amount of the engine oil with respect to the catalyst 60 at the present time.

(Step S120)
The poisoning amount derivation unit 112 executes the poisoning rate derivation process to derive the poisoning rate of the catalyst 60 at the present time.

(Step S130)
The poisoned amount derivation unit 112 executes the poisoned amount derivation process, and adds the poisoned amount derived this time to the integrated value of the poisoned amount up to the previous time.

(Step S140)
The drive control unit 110 determines whether or not it is the end timing of the driving cycle. As a result, if the drive control unit 110 determines that it is not the end timing of the driving cycle, the process is transferred to step S150, and if it is determined that it is the end timing of the driving cycle, the process is transferred to step S180. ..

(Step S150)
The drive control unit 110 determines whether or not the suppression flag described later is on. As a result, when the drive control unit 110 determines that the suppression flag is on, the process is transferred to step S160, and when it is determined that the suppression flag is not on, the drive control unit 110 shifts the process to step S170.

(Step S160)
The drive control unit 110 executes the mixing suppression process and ends the engine control process. For example, the drive control unit 110 executes a process of controlling the actuator 52 to increase the opening degree of the throttle valve 50 when cutting the supply of fuel to the engine 2 (for example, during deceleration) as a mixing suppression process. do. Further, the drive control unit 110 executes a process of reducing the engine speed as a process of suppressing mixing.

(Step S170)
The drive control unit 110 executes a normal control process and ends the engine control process.

(Step S180)
The poisoning amount determination unit 114 determines whether or not the poisoning amount (integrated value) derived in step S130 is equal to or greater than the threshold value Th. As a result, when the poisoning amount determination unit 114 determines that the poisoning amount is equal to or higher than the threshold value Th, the process is transferred to step S190, and when it is determined that the poisoning amount is not equal to or higher than the threshold value Th. The process is transferred to step S200.

(Step S190)
The poisoning amount determination unit 114 turns on the suppression flag and ends the engine control process.

(Step S200)
When the suppression flag is on, the poison amount determination unit 114 turns off the suppression flag and ends the engine control process.

As described above, according to the engine control device 1 and the engine control process using the engine control device 1 according to the present embodiment, the poisoning amount of the catalyst 60 is set to be equal to or less than the design value regardless of the operating state of the engine 2. can do. This makes it possible to maintain the purification performance of the catalyst 60. Further, the purification performance of the catalyst 60 can be maintained regardless of the tension of the piston ring. Therefore, the tension of the piston ring can be reduced, and the fuel efficiency can be improved. Therefore, it is possible to maintain the purification performance of the catalyst 60 and improve the fuel efficiency at the same time.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. Will be done.

In the above embodiment, the configuration in which the poisoning amount derivation unit 112 derives the poisoning amount based on the passing amount of the engine oil and the poisoning rate of the catalyst 60 by the poisoning substance has been described as an example. However, the poisoned amount derivation unit 112 may derive the poisoned amount by another method. For example, a toxic substance detection sensor for detecting a toxic substance is provided in the exhaust flow path 40, and the toxic amount derivation unit 112 derives the toxic amount based on the detection result of the toxic substance detection sensor. May be good.

Further, in the above embodiment, the configuration in which the poisoned amount deriving unit 112 derives the passing amount of the engine oil based on the engine load and the engine rotation speed has been described as an example. However, the poisoned amount deriving unit 112 may derive the passing amount of the engine oil by another method. For example, an engine oil detection sensor for detecting engine oil may be provided in the exhaust flow path 40, and the poisoning amount derivation unit 112 may derive the passing amount of engine oil based on the detection result of the engine oil detection sensor. ..

Further, in the above embodiment, the configuration in which the poisoning amount derivation unit 112 derives the poisoning rate of the catalyst 60 by the poisoning substance based on the temperature of the exhaust gas and the flow velocity of the exhaust gas has been described as an example. However, the poisoning amount derivation unit 112 does not have to derive the poisoning rate, and may be a fixed value, for example.

Further, in the above embodiment, the drive control unit 110 executes both a process of controlling the throttle opening when cutting the supply of fuel to the engine 2 and a process of controlling the engine speed as the mixing suppression process. The configuration is described as an example. However, even if the drive control unit 110 executes either a process of controlling the throttle opening when cutting the supply of fuel to the engine 2 or a process of controlling the engine speed as a mixing suppression process. good.

The present invention can be used for an engine control device that controls an engine.

1 Engine control device 110 Drive control unit (control processing execution unit)
112 Poisonous amount derivation unit 114 Poisonous amount determination unit

Claims (4)

The poisoning amount derivation unit that derives the poisoning amount of the catalyst by the poisonous substance contained in the exhaust gas, and
A poisoning amount determination unit that determines whether or not the poisoning amount is equal to or higher than a predetermined threshold value for each predetermined running period.
When it is determined that the poisoned amount is equal to or higher than the threshold value, the control process executing unit executes a process of suppressing the mixing of the poisoned substance into the exhaust gas of the engine in the next traveling period. ,
Equipped with
The toxic substance is contained in engine oil and
The poisoning amount deriving unit, the amount of engine oil that passes through the catalyst, and, on the basis of the poisoning rate of the catalyst due to poisoning substances, the engine control apparatus wherein you derive the poisoning amount. The engine control device according to claim 1 , wherein the poisoned amount deriving unit derives the amount of engine oil passing through the catalyst based on the engine load and the engine rotation speed. The engine control device according to claim 1 or 2 , wherein the poisoning amount deriving unit derives the poisoning rate of the catalyst by the poisoning substance based on the temperature of the exhaust gas and the flow velocity of the exhaust gas. The process of suppressing the mixing of the poisonous substance into the exhaust gas is either a process of controlling the throttle opening when cutting the supply of fuel to the engine or a process of controlling the engine rotation speed. The engine control device according to any one of claims 1 to 3, which is one or both.

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