JP3562315B2 - Evaporative fuel supply control device for lean burn internal combustion engine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for treating evaporated fuel generated in a fuel tank provided in an internal combustion engine, and more particularly to a technique for treating evaporated fuel in a lean burn internal combustion engine.
[0002]
[Prior art]
In recent years, in order to reduce the fuel consumption of the internal combustion engine, the development of a lean-burn internal combustion engine capable of burning a mixture having an air-fuel ratio higher than the stoichiometric air-fuel ratio (an air-fuel-rich mixture) has been promoted. As such a lean-burn internal combustion engine, an in-cylinder injection type internal combustion engine in which a fuel injection valve is attached so that an injection hole faces a combustion chamber is known.
[0003]
In a low-load operation range, a direct injection internal combustion engine introduces fresh air into a combustion chamber during an intake stroke, injects fuel from a fuel injection valve during a subsequent compression stroke, and emits a combustible mixture only near an ignition plug. Form. That is, the air-fuel mixture in the combustion chamber is in a so-called stratified state in which the vicinity of the ignition plug becomes a combustible air-fuel mixture layer and the other area becomes an air layer. The stratified air-fuel mixture is burned using a combustible air-fuel mixture layer near the ignition plug as an ignition source.
[0004]
Further, in the direct injection type internal combustion engine, in the medium load operation region, fuel is injected from the fuel injection valve at the same time as fresh air is introduced into the combustion chamber during the intake stroke. At this time, the amount of fuel injected from the fuel injection valve is such that the ratio of the amount of fuel to the amount of fresh air becomes higher than the stoichiometric air-fuel ratio. In this case, a lean mixture in which the fuel and fresh air are homogeneously mixed is formed over substantially the entire region in the combustion chamber.
[0005]
Subsequently, in the high-load operation region, the direct injection internal combustion engine introduces fresh air into the combustion chamber during the intake stroke and simultaneously injects fuel from the fuel injection valve. At this time, the amount of fuel injected from the fuel injection valve is an amount at which the ratio between the amount of fuel and the amount of fresh air is substantially equal to the stoichiometric air-fuel ratio. In this case, a stoichiometric mixture in which fuel and fresh air are homogeneously mixed is formed over substantially the entire area of the combustion chamber.
[0006]
As described above, the in-cylinder injection type internal combustion engine can realize lean combustion in the low-to-medium load operation region, and therefore can significantly reduce fuel consumption.
[0007]
On the other hand, an internal combustion engine mounted on an automobile or the like is provided with an evaporative fuel processing device for processing evaporative fuel generated in a fuel tank or the like. This evaporative fuel processing device is configured to temporarily store the evaporative fuel generated in the fuel tank, a charcoal canister, an air introduction passage for introducing air into the charcoal canister, and a suction pipe negative pressure generated in an intake passage downstream of the throttle valve. It comprises a negative pressure introducing passage for introducing into the charcoal canister, and a flow control valve for adjusting a flow rate in the negative pressure introducing passage.
[0008]
In the evaporative fuel processing apparatus configured as described above, when the flow control valve is closed, the evaporative fuel generated in the fuel tank is adsorbed by the adsorbent such as activated carbon installed in the charcoal canister. When the flow control valve is opened, the intake pipe negative pressure generated in the intake passage is applied to the charcoal canister via the negative pressure introduction passage. Thereby, the air is sucked into the charcoal canister through the air introduction passage. The air sucked into the charcoal canister is sucked into the intake passage through the negative pressure introduction passage. As described above, when the flow control valve is opened, a flow of the atmosphere flowing through the charcoal canister is generated.
[0009]
The fuel vapor adsorbed by the adsorbent is desorbed by the above-mentioned flow of the atmosphere, and is led to the intake passage together with the atmosphere. Evaporated fuel and air introduced into the intake passage (hereinafter, evaporative fuel and air introduced from the purge passage into the intake passage are referred to as purge gas) are mixed with fresh air from the upstream of the intake passage to the combustion chamber of the internal combustion engine. It is introduced and combusted and processed with the fuel injected from the fuel injection valve.
[0010]
When the purge of the fuel vapor is executed, the fuel injected from the fuel injection valve and the fuel vapor purged by the fuel vapor processing device are supplied to the combustion chamber of the internal combustion engine, and the air-fuel mixture becomes empty. The fuel ratio fluctuates. For this reason, in the internal combustion engine provided with the evaporative fuel processing device, it is necessary to control the purge supply amount and the fuel injection amount of the evaporative fuel in order to suppress the fluctuation of the air-fuel ratio.
[0011]
In response to such demands, a fuel supply control device for an internal combustion engine described in Japanese Patent Application Laid-Open No. 5-52139 is known. This supply fuel control device includes a purge control valve for adjusting a flow rate of a purge gas in a purge passage, and a reference purge rate which is a ratio of a purge amount to an intake air amount and is determined by an engine operating state for the same purge control valve opening. Purge control valve opening control means for controlling the opening of the purge control valve in accordance with the ratio of the purge control valve to the target purge rate; fuel injection quantity calculation means for calculating the fuel injection quantity; and an air-fuel ratio sensor provided in the exhaust system. A first injection amount correction means for correcting the fuel injection amount by a feedback correction coefficient so that the air-fuel ratio becomes a target air-fuel ratio based on an output signal of the air-fuel ratio sensor; Purge vapor concentration calculating means for calculating a purge vapor concentration based on the purge gas concentration, and second injection amount correcting means for correcting the fuel injection amount based on the purge vapor concentration at the time of executing the purge. And Bei, even when such that the purge vapor concentration in the intake air such as during acceleration operation decreases, a device which attempts to converge the air-fuel ratio to the target air-fuel ratio.
[0012]
[Problems to be solved by the invention]
In the fuel supply control device described above, when it is necessary to rapidly change the amount of fuel to be supplied to the combustion chamber (the amount of fuel supplied to the engine), the amount of fuel supplied to the engine is rapidly increased, for example, during deceleration. In the case of decreasing the fuel injection amount and the purge control valve, the fuel injection amount and the purge supply amount are reduced by controlling the fuel injection valve and the purge control valve.
[0013]
By the way, when the above-described fuel supply control device is applied to a direct injection internal combustion engine, the fuel injection valve directly injects fuel into the combustion chamber, so that a change in the fuel injection amount is immediately reflected in the engine supply fuel amount. However, since the purge gas adjusted by changing the opening of the purge control valve is supplied to the combustion chamber via the intake passage, the change in the opening of the purge control valve (change in the purge supply amount) is reflected on the engine supply fuel amount. It takes some time to complete. For this reason, when the engine supply fuel amount is rapidly changed, the change in the purge supply amount cannot follow the change in the fuel injection amount.
[0014]
If the amount of fuel supplied to the engine is to be reduced rapidly, excess evaporated fuel is supplied into the combustion chamber until the change in the amount of purge supply is reflected in the amount of fuel supplied to the engine. The fuel ratio does not reach the desired air-fuel ratio, and the combustion state of the internal combustion engine becomes unstable. In particular, when lean combustion (stratified combustion) is being performed in the internal combustion engine, there is a risk that rich misfire may be induced by the supply of excessive fuel vapor.
[0015]
The present invention has been made in view of the above-described problems, and in a lean-burn internal combustion engine capable of burning an air-fuel mixture in an excess oxygen state, in particular, in a direct injection internal combustion engine, the engine operation state is a deceleration operation state. When it becomes necessary to greatly reduce the amount of fuel supplied to the engine, as in the case of the transition to, the technology to prevent the fluctuation of the air-fuel ratio due to the delay in following the change of the purge supply amount with the change of the fuel injection amount. It is an object of the present invention to stabilize the combustion state of a lean-burn internal combustion engine, particularly the combustion state during lean-burn (stratified combustion).
[0016]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems. That is, the evaporative fuel supply control device for the lean burn internal combustion engine according to the present invention is a lean burn internal combustion engine capable of burning an air-fuel mixture in an excess oxygen state,
Engine operating state detecting means for detecting an operating state of the lean burn internal combustion engine,
A purge passage that guides fuel vapor generated in a fuel tank attached to the lean burn internal combustion engine to an intake system of the lean burn internal combustion engine;
A purge supply amount control unit that controls a purge supply amount of the evaporated fuel according to the engine operation state detected by the engine operation state detection unit;
An injection amount calculation unit that calculates a basic fuel injection amount of the lean burn internal combustion engine according to the engine operation state detected by the engine operation state detection unit;
An evaporative fuel supply control device for a lean burn internal combustion engine, comprising: a fuel injection amount correction unit that corrects the basic fuel injection amount calculated by the injection amount calculation unit in accordance with the purge supply amount,
Fuel injection change amount predicting means for predicting that the change in the fuel injection amount is larger than the change in the purge supply amount;
Purge supply amount changing means for changing the purge supply amount to a minimum supply amount when a change in the fuel injection amount is predicted to be larger than a change in the purge supply amount;
A minimum injection amount calculating means for calculating a fuel injection amount according to the minimum supply amount,
It is characterized by having.
[0017]
In the evaporative fuel supply control device configured as above, the purge supply amount control means controls the purge supply amount of the evaporative fuel according to the engine operating state. At this time, the fuel injection amount correction means corrects the basic fuel injection amount calculated by the injection amount calculation means according to the purge supply amount. In this case, the amount of fuel supplied to the combustion chamber of the lean burn internal combustion engine (the amount of fuel supplied to the engine) is determined by the fuel injection amount and the purge supply amount.
[0018]
The fuel injection change amount predicting unit predicts that the change in the fuel injection amount will be larger than the change in the purge supply amount based on the basic fuel injection amount and the purge supply amount calculated by the injection amount calculating unit. That is, it is determined whether or not it is predicted that the change in the purge supply amount cannot follow the change in the fuel injection amount.
[0019]
When the fuel injection change amount predicting unit predicts that the change in the fuel injection amount will be larger than the change in the purge supply amount, the purge supply amount changing unit changes the purge supply amount to the minimum supply amount. The minimum supply amount here may be zero or the minimum value of the purge supply amount that can be realized by the purge supply amount control unit.
[0020]
Then, the minimum injection amount calculating means calculates a fuel injection amount according to the minimum supply amount.
[0021]
As described above, the evaporative fuel supply control device according to the present invention immediately changes the purge supply amount to the minimum supply amount when predicting that the change in the fuel injection amount is larger than the change in the purge supply amount. Is prevented from following the change of the purge supply amount with respect to the change of the fuel supply amount, and the excessive evaporated fuel is not supplied to the combustion chamber of the lean burn internal combustion engine.
[0022]
Note that even when a delay in following the change in the purge supply amount with respect to the change in the fuel injection amount is predicted, if the vaporized fuel concentration is sufficiently low, the air-fuel mixture will be supplied even if excessive purge gas is supplied to the combustion chamber of the lean burn internal combustion engine. In such a case, the purge supply amount may not be changed in such a case.
[0023]
That is, the purge supply amount changing unit changes the purge supply amount to the minimum supply amount when the change in the fuel injection amount is predicted to be larger than the change in the purge supply amount and the concentration of the evaporated fuel is equal to or higher than the predetermined concentration. You may make it.
[0024]
The evaporative fuel supply control device according to the present invention may further include a fuel concentration change amount estimating means for estimating that the change in the evaporative fuel concentration is larger than the change in the purge supply amount. In this case, the purge supply amount changing unit predicts that the change in the fuel injection amount is larger than the change in the purge supply amount, or that the change in the evaporated fuel concentration is larger than the change in the purge supply amount. In this case, the purge supply amount is changed to the minimum supply amount.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of an evaporative fuel supply control device according to the present invention will be described below with reference to the drawings.
[0026]
<Embodiment 1>
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which an evaporative fuel supply control device according to the present invention is applied. The internal combustion engine 1 shown in FIG. 1 is a four-cycle in-cylinder injection type internal combustion engine including a plurality of cylinders 2 and a fuel injection valve 9 for directly injecting fuel into each cylinder 2.
[0027]
The internal combustion engine 1 includes a cylinder block 1b in which a plurality of cylinders 2 and a cooling water passage 1c are formed, and a cylinder head 1a fixed to an upper portion of the cylinder block 1b.
[0028]
A crankshaft 4 as an engine output shaft is rotatably supported by the cylinder block 1b. The crankshaft 4 is connected to a piston 3 slidably mounted in each cylinder 2.
[0029]
Above the piston 3, a combustion chamber 5 surrounded by the top surface of the piston 3 and the cylinder head 1a is formed. An ignition plug 6 is attached to the cylinder head 1a so as to face the combustion chamber 5, and an igniter 6a for applying a drive current to the ignition plug 6 is connected to the ignition plug 6.
[0030]
Further, in the cylinder head 1a, the opening ends of two intake ports 7 and two exhaust ports 8 are formed so as to face the combustion chamber 5, and the fuel injection valve is formed so that the injection holes face the combustion chamber 5. 9 is attached.
[0031]
The opening ends of the intake and exhaust ports 7 and 8 are opened and closed by an intake valve 70 and an exhaust valve 80 supported by the cylinder head 1a so as to be able to advance and retreat, and these intake and exhaust valves 70 and 80 are rotated by the cylinder head 1a. The intake camshaft 11 and the exhaust camshaft 12 which are freely supported advance and retreat.
[0032]
The intake side camshaft 11 and the exhaust side camshaft 12 are connected to the crankshaft 4 via a timing belt (not shown), and the rotation of the crankshaft 4 causes the intake side camshaft 11 and the exhaust side via the timing belt. The power is transmitted to the side camshaft 12.
[0033]
One of the two intake ports 7 communicating with each cylinder 2 has a flow path formed linearly from an open end formed on the outer wall of the cylinder head 1 a to an open end facing the combustion chamber 5. The other intake port 7 is constituted by a helical port having a flow path formed so as to turn from the open end of the outer wall of the cylinder head 1a toward the open end of the combustion chamber 5.
[0034]
Each intake port 7 communicates with each branch pipe of the intake branch pipe 16 attached to the cylinder head 1a. A branch pipe communicating with a straight port of the two intake ports 7 is provided with a swirl control valve 10 for adjusting a flow rate in the branch pipe. The swirl control valve 10 is provided with an actuator 10a comprising a stepping motor or the like and driving the swirl control valve 10 to open and close according to an applied current.
[0035]
The intake branch pipe 16 is connected to a surge tank 17, and the surge tank 17 is connected to an air cleaner box 19 via an intake pipe 18. A vacuum sensor 20 that outputs an electric signal corresponding to the pressure in the surge tank 17 is attached to the surge tank 17.
[0036]
A throttle valve 21 for adjusting a flow rate in the intake pipe 18 is attached to the intake pipe 18. The throttle valve 21 is provided with an actuator 22 such as a step motor for opening and closing the throttle valve 21 in accordance with an applied current.
[0037]
The throttle valve 21 is provided with a throttle position sensor 23 for outputting an electric signal corresponding to the opening of the throttle valve 21 and an accelerator lever (not shown) which rotates in conjunction with an accelerator pedal 24. .
[0038]
An accelerator position sensor 25 that outputs an electric signal corresponding to the rotational position of the accelerator lever (the amount of depression of the accelerator pedal 24) is attached to the accelerator lever.
[0039]
An air flow meter 26 that outputs an electric signal corresponding to a mass of fresh air flowing through the intake pipe 18 (a mass of intake air) is attached to the intake pipe 18 upstream of the throttle valve 21.
[0040]
On the other hand, each exhaust port 8 communicates with each branch pipe of an exhaust branch pipe 27 attached to the cylinder head 1a, and the exhaust branch pipe 27 is connected to an exhaust pipe 29 via a first catalyst 28. The exhaust pipe 29 is connected downstream to a muffler (not shown).
A first air-fuel ratio sensor 30 that outputs an electric signal corresponding to the air-fuel ratio of the exhaust gas flowing through the exhaust branch pipe 27 is attached to the exhaust branch pipe 27.
[0041]
In the middle of the exhaust pipe 29, a second catalyst 31 is provided. The exhaust pipe 29 downstream of the second catalyst 31 corresponds to the air-fuel ratio of the exhaust gas flowing out of the second catalyst 31. A second air-fuel ratio sensor 32 that outputs an electric signal is attached.
[0042]
The first catalyst 28 is a three-way catalyst having a smaller capacity than the second catalyst 31, and the second catalyst 31 is a three-way catalyst, a nitrogen oxide storage reduction catalyst, or the like.
[0043]
Next, the internal combustion engine 1 is provided with a fuel tank 33 and a charcoal canister 34 for temporarily storing fuel vapor generated in the fuel tank 33. The fuel tank 33 and the charcoal canister 34 are connected via an evaporative fuel passage 35. In the middle of the evaporative fuel passage 35, a flow path in the evaporative fuel passage 35 is formed according to the pressure in the fuel tank 33. A tank internal pressure control valve 36 that opens and closes is mounted.
[0044]
The tank internal pressure control valve 36 is configured by combining a positive pressure valve and a negative pressure valve, and the positive pressure valve opens when the pressure in the fuel tank 33 becomes equal to or more than a first predetermined value due to an increase in the amount of fuel vapor. The negative pressure valve opens when the pressure in the fuel tank 33 falls below a second predetermined value (<first predetermined value) due to a decrease in fuel.
[0045]
An air introduction passage 37 is connected to the charcoal canister 34, and the air introduction passage 37 is connected to the intake pipe 18 located between the air flow meter 26 and the throttle valve 21.
[0046]
Further, a negative pressure introducing passage 38 is connected to the charcoal canister 34, and the negative pressure introducing passage 38 is connected to the intake pipe 18 downstream of the throttle valve 21. An electromagnetic valve 39 for adjusting the flow rate in the negative pressure introduction passage 38 is provided in the middle of the negative pressure introduction passage 38.
[0047]
The atmosphere introduction passage 37 and the negative pressure introduction passage 38 that communicate with each other via the charcoal canister 34 realize a purge passage according to the present invention (hereinafter, the charcoal canister 34, the atmosphere introduction passage 37, and the negative pressure introduction passage 38 are collectively referred to as the purge passage). And described as a purge passage 49).
[0048]
The internal combustion engine 1 is also provided with an electronic control unit (Electronic Control Unit: ECU) 40 for engine control. The ECU 40 includes a vacuum sensor 20, a throttle position sensor 23, an accelerator position sensor 25, an air flow meter , A first air-fuel ratio sensor 30 and a second air-fuel ratio sensor 32, a timing rotor 13a attached to the end of the crankshaft 4, and an electromagnetic pickup 13b attached to a cylinder block 1b near the timing rotor 13a. Various sensors such as a crank position sensor 13 and a water temperature sensor 14 attached to the cylinder block 1b to detect the temperature of the cooling water flowing in the cooling water passage 1c of the cylinder block 1b are connected via electric wiring.
[0049]
Further, the igniter 6a, the fuel injection valve 9, the actuator 10a, the actuator 22, the electromagnetic valve 39, and the like are connected to the ECU 40 via electric wiring.
[0050]
The ECU 40 determines the operating state of the internal combustion engine 1, the evaporated fuel adsorption state of the charcoal canister 34, and the like using the output signals from the various sensors as parameters, and according to the determination result, the igniter 6a, the fuel injection valve 9, the actuator 10a And various controls of the actuator 22, the electromagnetic valve 39, and the like.
[0051]
Here, as shown in FIG. 2, the ECU 40 includes a CPU 42, a ROM 43, a RAM 44, a backup RAM 45, an input port 46, and an output port 47, which are interconnected by a bidirectional bus 41. A / D converter (A / D) 48 connected to the
[0052]
The input port 46 inputs signals output from the crank position sensor 13, the throttle position sensor 23, and the accelerator position sensor 25, and transmits the output signals to the CPU 42 or the RAM 44.
[0053]
Further, the input port 46 inputs signals output from the water temperature sensor 14, the vacuum sensor 20, the air flow meter 26, and the first and second air-fuel ratio sensors 30 and 32 via the A / D 48, and outputs the signals. The signal is transmitted to the CPU 42 or the RAM 44.
[0054]
The output port 47 outputs a control signal output from the CPU 42 to the igniter 6a, the fuel injection valve 9, the actuator 10a, the actuator 22, the electromagnetic valve 39, or the like.
[0055]
The ROM 43 executes a fuel injection amount control routine for determining a fuel injection amount, a fuel injection timing control routine for determining a fuel injection timing, an ignition timing control routine for determining an ignition timing, and purging of evaporated fuel. Application programs, such as a purge execution control routine, and various control maps.
[0056]
The control map includes, for example, a fuel injection amount control map indicating the relationship between the operating state of the internal combustion engine 1 and the fuel injection amount, a fuel injection timing control map indicating the relationship between the operating state of the internal combustion engine 1 and the fuel injection timing, There are an ignition timing control map indicating the relationship between the operating state of the engine 1 and the ignition timing, a purge flow rate control map indicating the relationship between the operating state of the internal combustion engine 1 or the state of the charcoal canister 34 and the opening of the solenoid valve 39, and the like.
[0057]
The RAM 44 stores an output signal of each sensor, a calculation result of the CPU 42, and the like. The calculation result is, for example, an engine speed calculated based on an output signal of the crank position sensor 13. Then, the output signal of each sensor, the calculation result of the CPU 42 and the like are rewritten to the latest data every time the crank position sensor 13 outputs a signal.
[0058]
The backup RAM 45 is a nonvolatile memory that retains data even after the operation of the internal combustion engine 1 is stopped.
[0059]
The CPU 42 operates according to the application program stored in the ROM 43, determines the operating state of the internal combustion engine 1 and the state of the charcoal canister 34 from the output signals of the sensors, and determines the determined operating state and the state of the charcoal canister 34. From each control map, the fuel injection amount, fuel injection timing, opening degree of throttle valve 21, ignition timing, opening / closing timing of solenoid valve 39, opening degree of solenoid valve 39 (duty ratio for controlling solenoid valve 39: DPG), purge execution A correction amount of the fuel injection amount at the time (fuel injection correction amount: FPG) and the like are calculated. Then, the CPU 42 outputs a control signal to the igniter 6a, the fuel injection valve 9, the actuator 10a, the actuator 22, or the electromagnetic valve 39 based on the calculation result.
[0060]
For example, when the CPU 42 determines from the output signal value of the crank position sensor 13, the accelerator position sensor 25, or the air flow meter 26 that the operation state of the internal combustion engine 1 is in the low load operation region, the CPU 42 performs stratified combustion. The control signal is transmitted to the actuator 10a to reduce the opening of the swirl control valve 10, the control signal is transmitted to the actuator 22 to make the throttle valve 21 substantially fully open, and the fuel is supplied during the compression stroke of each cylinder 2. A compression stroke injection is performed by applying a drive current to the injection valve 9. In this case, in the combustion chamber 5 of each cylinder 2, a combustible mixture layer is formed only in the vicinity of the ignition plug 6, and an air layer is formed in other regions, so that stratified combustion is realized.
[0061]
When it is determined that the engine operation state is in the medium load operation region, the CPU 42 transmits a control signal to the actuator 10a to reduce the opening of the swirl control valve 10 in order to realize homogeneous lean combustion by the lean mixture. Further, during the intake stroke of each cylinder 2, a drive current is applied to the fuel injection valve 9 to perform the intake stroke injection. In this case, a lean mixture in which air and fuel are homogeneously mixed is formed over substantially the entire area of the combustion chamber 5 of each cylinder 2, and homogeneous lean combustion is realized.
[0062]
If it is determined that the engine operation state is in the high load operation range, the CPU 42 transmits a control signal to the actuator 10a to fully open the swirl control valve 10 in order to realize homogeneous combustion by the air-fuel mixture near the stoichiometric air-fuel ratio. A control signal is transmitted to the actuator 22 so that the throttle valve 21 has an opening corresponding to the depression amount of the accelerator pedal 24 (the output signal value of the accelerator position sensor 25). 9, a drive current is applied to perform intake stroke injection. In this case, a mixture having a stoichiometric air-fuel ratio in which air and fuel are homogeneously mixed is formed over substantially the entire area of the combustion chamber 5 of each cylinder 2, and homogeneous combustion is realized.
[0063]
When shifting from the stratified combustion control to the homogeneous combustion control, or when shifting from the homogeneous combustion control to the stratified combustion control, the CPU 42 performs the compression stroke of each cylinder 2 and the intake stroke in order to prevent the torque fluctuation of the internal combustion engine 1. A drive current is applied to the fuel injection valve 9 in two stages of the stroke. In this case, in the combustion chamber 5 of each cylinder 2, a combustible mixture layer is formed in the vicinity of the ignition plug 6, and a lean mixture layer is formed in other regions, so-called weak stratified combustion is realized. .
[0064]
When the CPU 42 determines that the engine operation state is in the idle operation region, the opening degree of the throttle valve 21 is secured to secure an intake air amount necessary for converging the actual engine speed to the target idle speed. , That is, feedback control of so-called idle speed control (ISC).
[0065]
Next, when performing the purge of the evaporated fuel, the CPU 42 performs control so that the electromagnetic valve 39 is normally closed. In this state, when the fuel vapor in the fuel tank 33 increases and the pressure in the fuel tank 33 exceeds the first predetermined value, the positive pressure valve of the tank internal pressure control valve 36 is opened, and the fuel vapor passage 35 is in a conductive state. It becomes. Then, the evaporated fuel in the fuel tank 33 is introduced into the charcoal canister 34 via the evaporated fuel passage 35, and is once adsorbed by an adsorbent such as activated carbon provided in the charcoal canister 34.
[0066]
Further, the CPU 42 determines whether or not the purge execution condition of the evaporated fuel is satisfied at predetermined time intervals. As this purge execution condition, for example, the fuel cut execution condition in which the warm-up of the internal combustion engine 1 and the first and second catalysts 28 and 31 is completed is not satisfied (that is, the fuel cut valve 9 The fuel injection amount is equal to or more than a predetermined amount), or a condition that a predetermined time or more has elapsed after the start of the internal combustion engine 1 can be exemplified.
[0067]
If it is determined that the purge execution condition described above is satisfied, the CPU 42 opens the solenoid valve 39. In this case, the negative pressure introduction passage 38 becomes conductive, and thereby the purge passage 49 becomes conductive.
[0068]
Here, the inside of the intake pipe 18 upstream of the throttle valve 21 corresponding to the upstream of the purge passage 49 has a substantially atmospheric pressure: PA, but the pressure in the intake pipe 18 downstream of the throttle valve 21 downstream of the purge passage 49 (intake pipe pressure). : PM becomes negative pressure due to the generation of the suction pipe negative pressure, so that a pressure difference ΔPM (= PA−PM) is generated between the upstream and downstream of the purge passage 49.
[0069]
Due to the above-mentioned pressure difference: ΔPM, a part of the atmosphere flowing in the intake pipe 18 upstream of the throttle valve 21 flows into the purge passage 49 and is guided into the intake pipe 18 downstream of the throttle valve 21. That is, in the purge passage 49, a flow of the air flowing through the charcoal canister 34 is generated.
[0070]
At this time, the evaporated fuel that has been adsorbed by the adsorbent in the charcoal canister 34 receives the flow of the air, desorbs from the adsorbent, and is introduced into the intake pipe 18 downstream of the throttle valve 21 together with the air. The atmosphere and evaporated fuel (purge gas) introduced into the intake pipe 18 are introduced into the combustion chamber 5 while being mixed with fresh air flowing from the upstream of the intake pipe 18, and are injected from the fuel injection valve 9. It is burned and processed together with the fuel.
[0071]
The amount of purge gas supplied to the combustion chamber 5 (purge supply amount) is adjusted by the CPU 42 controlling the opening of the solenoid valve 39 in accordance with the engine operating state and the state of the charcoal canister 34. Specifically, the CPU 42 accesses the purge flow rate control map in the ROM 43 using the engine operation state and the state of the charcoal canister 34 as parameters, and calculates the solenoid valve 39 control duty ratio: DPG. Then, the CPU 42 adjusts the purge supply amount by applying a drive pulse signal corresponding to the calculated electromagnetic valve 39 control duty ratio: DPG to the electromagnetic valve 39.
[0072]
On the other hand, the CPU 42 sets the air-fuel ratio of the air-fuel mixture in the combustion chamber 5 to a desired air-fuel ratio during the execution of the purge, in other words, the total amount of fuel supplied into the combustion chamber 5 (the fuel injection amount and the purge supply amount). The fuel injection amount is corrected in accordance with the purge supply amount in order to make the total amount of the fuel injection amount a desired amount.
[0073]
At that time, the CPU 42 operates in accordance with the fuel injection amount control routine, and uses the engine speed calculated based on the output signal of the crank position sensor 13 and the output signal value (accelerator opening) of the accelerator position sensor 25 as parameters in the ROM 43. The fuel injection amount control map is accessed, and a basic fuel injection amount: QALL corresponding to the engine speed and the accelerator opening is interpolatively calculated. A plurality of fuel injection amount control maps are prepared according to the operating conditions or the combustion mode, and are appropriately selected from the maps.
[0074]
Subsequently, the CPU 42 calculates the actual fuel injection amount: QALLINJ by subtracting the fuel injection correction amount: FPG from the basic fuel injection amount: QALL calculated according to the fuel injection amount control routine. Then, the CPU 42 drives the fuel injection valve 9 according to the fuel injection amount: QALLINJ.
[0075]
Further, when the vehicle decelerates during the execution of the purge, or when the vehicle shifts from a flat road traveling state to a downhill traveling state, the required amount of the total fuel amount (hereinafter, referred to as a required total fuel amount) rapidly increases. As shown in FIG. 3, the CPU 42 controls the fuel injection valve 9 and the solenoid valve 39 to decrease the actual total fuel amount.
[0076]
Here, since the fuel injection valve 9 directly injects fuel into the combustion chamber 5, the control of the fuel injection valve 9 is immediately reflected in the total fuel amount. Because of the distance, it takes some time before the control of the solenoid valve 39 is reflected on the total fuel amount. Until the control of the solenoid valve 39 is reflected in the total fuel amount, the change in the fuel injection amount becomes larger than the change in the purge supply amount. Injection amount). As a result, the actual total fuel amount becomes larger than the required total fuel amount, and the air-fuel ratio of the air-fuel mixture becomes lower than the desired air-fuel ratio. At this time, if the internal combustion engine 1 is in the stratified combustion operation state or the homogeneous lean combustion operation state, the air-fuel ratio becomes remarkably fluctuated, which may cause a rich misfire or the like.
[0077]
Therefore, in the present embodiment, when it is predicted that the required total fuel amount rapidly decreases, such as at the time of deceleration, the control of the purge supply amount cannot follow the control of the fuel injection amount, What is called a purge cut, in which the purge of the fuel vapor is stopped, is performed.
[0078]
Specifically, when the basic fuel injection amount: QALL is calculated in the fuel injection amount control routine, the CPU 42 writes the calculated basic fuel injection amount: QALL into a predetermined area of the RAM 44 and calculates the previously calculated basic fuel injection amount: QALL. Basic fuel injection amount: QALL _O From the RAM 44. Then, the CPU 42 calculates the previous basic fuel injection amount: QALL _O Is subtracted from the current basic fuel injection amount: QALL to calculate a change amount of the fuel injection amount (fuel injection change amount): △ QALL.
[0079]
The CPU 42 determines whether or not the fuel injection change amount 噴射 QALL is larger than a predetermined reference value: ST, that is, whether or not the fuel injection amount tends to decrease and the decrease amount exceeds the reference value: ST. I do. The reference value: ST is the maximum value of the fuel injection change amount in a range where the control of the purge supply amount can follow the control of the fuel injection amount, and the engine speed, the intake air amount, the intake pipe pressure, and the like are used as parameters. It is calculated from the reference value control map obtained.
[0080]
When it is determined that the fuel injection change amount: △ QALL is equal to or smaller than the reference value: ST, the CPU 42 executes a normal solenoid valve 39 control duty ratio calculation process to execute the solenoid valve 39 control duty ratio: DPG. Is calculated. Next, the CPU 42
The fuel injection correction amount: FPG corresponding to the solenoid valve 39 control duty ratio: DPG is calculated, and the actual fuel injection amount: QALLINJ is calculated by subtracting the fuel injection correction amount: FPG from the basic fuel injection amount: QALL. I do.
[0081]
On the other hand, if it is determined that the fuel injection change amount: ΔQALL is larger than the reference value: ST, the CPU 42 determines that the control of the purge supply amount cannot follow the control of the fuel injection amount, and the electromagnetic valve 39. The control duty ratio: DPG is set to “0%”, and purge cut is executed.
[0082]
Subsequently, the CPU 42 calculates the fuel injection correction amount: FPG and the fuel injection amount: QALLINJ assuming that the duty ratio for control of the solenoid valve 39: DPG is “0%”, and performs the fuel injection according to the calculated fuel injection amount: QALLINJ. Actuate the valve 9. In this case, the reduction of the total amount of fuel supplied to the combustion chamber 5 of the internal combustion engine 1 is performed only by controlling the fuel injection valve 9.
[0083]
As described above, the CPU 42 executes the application program stored in the ROM 43 to execute the engine operating state detecting means, the purge supply amount controlling means, the injection amount calculating means, the fuel injection amount correcting means, the fuel injection amount correcting means, and the fuel injection change amount according to the present invention. An amount estimating unit, a purge supply amount changing unit, and a minimum injection amount calculating unit are realized.
[0084]
Hereinafter, a specific purge control according to the present embodiment will be described.
[0085]
The CPU 42 repeatedly executes a purge execution control routine as shown in FIG. 4 at predetermined time intervals when the lean burn internal combustion engine 1 is operating.
[0086]
In the purge execution control routine, the CPU 42 determines whether the purge execution condition is satisfied in S401.
[0087]
If it is determined in S401 that the purge execution condition is not satisfied, the CPU 42 proceeds to S408, sets both the fuel injection correction amount: FPG and the duty ratio DPG for controlling the solenoid valve 39 to “0”, and executes this routine. Execution is temporarily terminated.
[0088]
On the other hand, if it is determined in step S401 that the purge execution condition is satisfied, the CPU 42 proceeds to step S402, where the current basic fuel injection amount: QALL calculated by a separate fuel injection amount control routine and the previous basic fuel injection amount. Injection amount: QALL _O From the RAM 44.
[0089]
In S403, the CPU 42 determines that the previous basic fuel injection amount: QALL _O Is subtracted from the current basic fuel injection amount: QALL to calculate a fuel injection change amount: △ QALL.
[0090]
In S404, the CPU 42 accesses the reference value control map of the ROM 43 using the engine speed, the intake air amount, and the like as parameters, and calculates a reference value: ST of the fuel injection change amount.
[0091]
In S405, the CPU 42 determines whether or not the fuel injection change amount △ QALL calculated in S403 is larger than the reference value ST calculated in S404.
[0092]
When it is determined in S405 that the fuel injection change amount: △ QALL is equal to or smaller than the reference value: ST, the CPU 42 can follow the change in the fuel injection amount with the change in the purge supply amount, and executes the purge control. It is considered possible, and the process proceeds to S409.
[0093]
In S409, the CPU 42 performs a normal solenoid valve 39 control duty ratio: DPG calculation process. Specifically, the CPU 42 executes a separate purge execution control routine to calculate a duty ratio for controlling the solenoid valve 39: DPG.
[0094]
Subsequently, in S410, the CPU 42 calculates a fuel injection correction amount: FPG corresponding to the solenoid valve 39 control duty ratio: DPG calculated in S409.
[0095]
In S411, the CPU 42 subtracts the fuel injection correction amount: FPG calculated in S410 from the current basic fuel injection amount: QALL input in S402, and obtains the actual fuel injection amount: QALLINJ (= QALL-FPG). Is calculated.
[0096]
In this case, the total amount of fuel supplied to the combustion chamber 5 of the internal combustion engine 1 is adjusted by controlling the fuel injection valve 9 and the solenoid valve 39.
[0097]
On the other hand, if it is determined in S405 that the fuel injection change amount: △ QALL is larger than the reference value: ST, the CPU 42 determines that the change in the purge supply amount cannot follow the change in the fuel injection amount and the purge control Is not executable, and the process proceeds to S406.
[0098]
In S406, the CPU 42 sets both the fuel injection correction amount: FPG and the solenoid valve 39 control duty ratio: DPG to “0”.
[0099]
In S407, the CPU 42 applies a drive pulse signal (purge cut signal) corresponding to the duty ratio for controlling the electromagnetic valve 39 set in S407 to 0% to the electromagnetic valve 39, and stops purging of the fuel vapor.
[0100]
After completing the process of S407, the CPU 42 proceeds to S411, and subtracts the fuel injection correction amount: FPG (= 0) calculated in S406 from the basic fuel injection amount: QALL input in S402 to obtain the actual value. A fuel injection amount: QALLINJ (= QALL-FPG) is calculated.
[0101]
In this case, the purge of the evaporated fuel is stopped, and the total amount of fuel supplied to the combustion chamber 5 of the internal combustion engine 1 is adjusted by controlling only the fuel injection valve 9.
[0102]
According to the above-described embodiment, when it is predicted that the required total fuel amount is rapidly reduced during the execution of the purge and the change in the purge supply amount cannot follow the change in the fuel injection amount, the purge of the evaporated fuel is performed. Since the suspension is stopped and the total fuel amount is reduced only by controlling the fuel injection valve 9, the total fuel amount can be immediately reduced to the required total fuel amount. As a result, excessive fuel is not supplied into the combustion chamber 5, fluctuations in the air-fuel ratio of the air-fuel mixture are prevented, and the combustion state of the internal combustion engine 1 does not become unstable.
[0103]
<Embodiment 2>
A second embodiment of the evaporative fuel supply control device according to the present invention will be described with reference to the drawings. Here, a configuration different from that of the above-described first embodiment will be described, and a description of a similar configuration will be omitted.
[0104]
In the first embodiment, when it is predicted that the change in the purge supply amount cannot follow the change in the fuel injection amount, the purge is stopped regardless of the fuel concentration in the purge gas. As described above, in the present embodiment, it is predicted that the change in the purge supply amount cannot follow the change in the fuel injection amount, and the purge cut is performed only when the fuel concentration in the purge gas is higher than a predetermined concentration. An example of execution will be described. This is because, when the fuel concentration in the purge gas is equal to or lower than a predetermined concentration, the change in the purge supply amount cannot follow the change in the fuel injection amount. This is because the fluctuation of the air-fuel ratio does not fall outside the allowable range.
[0105]
In this case, the CPU 42 repeatedly executes a purge execution control routine as shown in FIG. 5 every predetermined time.
[0106]
In the purge execution control routine, the CPU 42 determines whether the purge execution condition is satisfied in S501.
[0107]
If it is determined in step S501 that the purge execution condition is not satisfied, the CPU 42 proceeds to step S509 and sets both the fuel injection correction amount: FPG and the duty ratio DPG for controlling the solenoid valve 39 to “0”. Execution is temporarily terminated.
[0108]
On the other hand, if it is determined in S501 that the purge execution condition is satisfied, the CPU 42 proceeds to S502 and determines whether or not the evaporated fuel concentration in the purge gas is higher than a predetermined concentration: CEVAP. Here, the concentration of the evaporated fuel is determined by providing an HC sensor in the purge passage to detect the concentration of the evaporated fuel, by providing an air-fuel ratio sensor in the intake passage or the exhaust passage to determine the concentration of the evaporated fuel, or It is obtained by a method of estimating the concentration of the evaporated fuel from a change in the operating state of the internal combustion engine at the time of purging (for example, a change in output).
[0109]
If it is determined in step S502 that the fuel vapor concentration in the purge gas is equal to or lower than the predetermined concentration: CEVAP, the CPU 42 proceeds to step S510, and executes a normal electromagnetic valve 39 control duty ratio: DPG calculation process.
[0110]
Subsequently, in S511, the CPU 42 calculates the fuel injection correction amount: FPG corresponding to the solenoid valve 39 control duty ratio: DPG calculated in S510.
[0111]
In S512, the CPU 42 calculates the actual fuel injection amount: QALLINJ (= QALL-FPG) by subtracting the fuel injection correction amount: FPG from the basic fuel injection amount: QALL.
[0112]
In this case, the total amount of fuel supplied to the combustion chamber 5 of the internal combustion engine 1 is adjusted by controlling the fuel injection valve 9 and the solenoid valve 39.
[0113]
On the other hand, if it is determined in step S502 that the fuel vapor concentration in the purge gas is higher than the predetermined concentration: CEVAP, the CPU 42 proceeds to step S503. Here, the processing after S503 is the same as the processing after S402 of the purge execution control routine according to the above-described first embodiment.
[0114]
According to the present embodiment, even if it is predicted that the change in the purge supply amount cannot follow the change in the fuel injection amount, if the fuel concentration in the purge gas is equal to or lower than the predetermined concentration, the purge of the evaporated fuel is stopped. Since the combustion is continued, it is possible to secure the purge supply amount of the evaporated fuel without making the combustion state of the internal combustion engine 1 unstable.
[0115]
<Embodiment 3>
A third embodiment of the evaporative fuel supply control device according to the present invention will be described with reference to the drawings. Here, a configuration different from that of the above-described first embodiment will be described, and a description of a similar configuration will be omitted.
[0116]
In the present embodiment, it is predicted that the change in the purge supply amount cannot follow the change in the fuel injection amount, and the purge cut-off is performed only when a predetermined amount of new fuel is supplied into the fuel tank 33. An example of executing is described.
[0117]
This is because, immediately after new fuel is supplied into the fuel tank 33, the evaporated fuel concentration becomes high, and if the refueling amount at that time is larger than a predetermined amount, the fuel vapor concentration is expected to be higher than the predetermined concentration. That's why.
[0118]
In this case, the CPU 42 repeatedly executes a purge execution control routine as shown in FIG. 6 every predetermined time.
[0119]
In the purge execution control routine, the CPU 42 determines whether the purge execution condition is satisfied in S601.
[0120]
If it is determined in step S601 that the purge execution condition is not satisfied, the CPU 42 proceeds to step S609, sets both the fuel injection correction amount: FPG and the duty ratio for control of the solenoid valve 39: DPG to “0”, and executes this routine. Execution is temporarily terminated.
[0121]
On the other hand, if it is determined in step S601 that the purge execution condition is satisfied, the CPU 42 proceeds to step S602, and determines whether the amount of fresh fuel supplied is greater than a predetermined amount: QFUEL. As a method of detecting the refueling amount of the new fuel, a method of comparing a previous output signal value of a fuel amount sensor for detecting a fuel amount in the fuel tank 33 with a current output signal value can be exemplified. The predetermined amount: QFUEL is a value obtained in advance by an experiment or the like.
[0122]
If it is determined in S602 that the refueling amount of the new fuel is equal to or less than the predetermined amount: QFUEL, the CPU 42 proceeds to S610 and executes a normal solenoid valve 39 control duty ratio: DPG calculation process.
[0123]
Subsequently, in S611, the CPU 42 calculates a fuel injection correction amount: FPG corresponding to the solenoid valve 39 control duty ratio: DPG calculated in S610.
[0124]
In S612, the CPU 42 calculates the actual fuel injection amount: QALLINJ (= QALL-FPG) by subtracting the fuel injection correction amount: FPG from the basic fuel injection amount: QALL.
[0125]
In this case, the total amount of fuel supplied to the combustion chamber 5 of the internal combustion engine 1 is adjusted by controlling the fuel injection valve 9 and the solenoid valve 39.
[0126]
On the other hand, if it is determined in S602 that the refueling amount of the new fuel is larger than the predetermined amount: QFUEL, the CPU 42 proceeds to S603. Here, the processing after S603 is the same as the processing after S402 of the purge execution control routine according to the above-described first embodiment.
[0127]
According to the present embodiment, since the evaporative fuel concentration is estimated based on the amount of new fuel supplied, even if a sensor or the like that detects the evaporative fuel concentration fails, it is possible to suppress a change in the air-fuel ratio of the air-fuel mixture.
[0128]
In the first to third embodiments described above, when it is predicted that the change in the purge supply amount cannot follow the change in the fuel injection amount, the purge of the evaporated fuel is stopped and the mixing is stopped. Although the example of preventing the fluctuation of the air-fuel ratio of gas has been described, in addition to the case where it is predicted that the change of the purge supply amount cannot follow the change of the fuel injection amount, the change of the purge supply amount Also, when it is predicted that the change of the air-fuel ratio cannot be followed, the purge of the evaporated fuel may be stopped to prevent the fluctuation of the air-fuel ratio of the air-fuel mixture.
[0129]
In the first to third embodiments described above, the example in which the purge of the evaporated fuel is stopped when it is predicted that the change in the purge supply amount cannot follow the change in the fuel injection amount. As described above, the purge supply amount may be changed to the minimum supply amount (minimum value) without stopping the purge of the evaporated fuel. When changing the purge supply amount to the minimum supply amount, the CPU 42 sets, for example, the duty ratio DPG for controlling the solenoid valve 39 to a minimum value (for example, 10%) within a range in which the solenoid valve 39 operates effectively. Alternatively, the purge of the evaporated fuel may be continued while suppressing the fluctuation of the air-fuel ratio within an allowable range. According to such control, the purge supply amount can be ensured while the combustion of the internal combustion engine is stabilized, so that the overflow of the charcoal canister is suppressed.
[0130]
【The invention's effect】
The evaporative fuel supply control device according to the present invention, when predicting that the change in the fuel injection amount is larger than the change in the purge supply amount, that is, that the change in the purge supply amount cannot follow the change in the fuel injection amount In addition, since the purge supply amount is changed to the minimum supply amount and the fuel injection amount is controlled based on the minimum supply amount, a delay in following the change in the purge supply amount with respect to the change in the fuel injection amount is prevented, and the excess fuel vapor Is not supplied to the combustion chamber of the lean burn internal combustion engine.
[0131]
Therefore, according to the present invention, the combustion state of the lean-burn internal combustion engine, in particular, the combustion state during execution of the lean combustion does not become unstable.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a lean burn internal combustion engine to which an evaporative fuel supply control device according to the present invention is applied;
FIG. 2 is a block diagram showing an internal configuration of an ECU.
FIG. 3 is a diagram showing a relationship between a fuel injection amount and a purge supply amount during deceleration traveling.
FIG. 4 is a flowchart showing a purge execution control routine.
FIG. 5 is a flowchart illustrating a purge execution control routine according to a second embodiment;
FIG. 6 is a flowchart illustrating a purge execution control routine according to a third embodiment;
[Explanation of symbols]
1 .... lean-burn internal combustion engine
4 ... Crankshaft
5 ... Combustion chamber
7 ... intake port
9 ... fuel injection valve
13. Crank position sensor
14. Water temperature sensor
16. Intake branch pipe
17. Surge tank
18. Intake pipe
19. Air cleaner box
21 ・ ・ Throttle valve
23 Throttle position sensor
25 ・ ・ Accelerator position sensor
26 Air flow meter
33 ... Fuel tank
34 Charcoal Canister
35 ・ ・ Evaporation fuel passage
36 ・ ・ Tank internal pressure control valve
37 ... Atmosphere introduction passage
38 Negative pressure introduction passage
39 ... solenoid valve
40 ECU
49 Purge passage

Claims (5)

A lean-burn internal combustion engine capable of burning a mixture in an oxygen-excess state;
Engine operating state detecting means for detecting an operating state of the lean burn internal combustion engine,
A purge passage that guides fuel vapor generated in a fuel tank attached to the lean burn internal combustion engine to an intake system of the lean burn internal combustion engine;
A purge supply amount control unit that controls a purge supply amount of the evaporated fuel according to the engine operation state detected by the engine operation state detection unit;
An injection amount calculation unit that calculates a basic fuel injection amount of the lean burn internal combustion engine according to the engine operation state detected by the engine operation state detection unit;
An evaporative fuel supply control device for a lean burn internal combustion engine, comprising: a fuel injection amount correction unit that corrects the basic fuel injection amount calculated by the injection amount calculation unit in accordance with the purge supply amount,
Fuel injection change amount prediction means for predicting that the change in the fuel injection amount when performing fuel injection is larger than the change in the purge supply amount,
Purge supply amount changing means for changing the purge supply amount to a minimum supply amount when a change in the fuel injection amount is predicted to be larger than a change in the purge supply amount;
A minimum injection amount calculating means for calculating a fuel injection amount according to the minimum supply amount,
An evaporative fuel supply control device for a lean burn internal combustion engine, comprising: 2. The evaporative fuel supply control device for a lean burn internal combustion engine according to claim 1, wherein the lean burn internal combustion engine is a direct injection internal combustion engine. 2. The lean burn internal combustion engine according to claim 1, wherein the purge supply amount changing unit stops the purge of the evaporated fuel when the change in the fuel injection amount is predicted to be larger than the change in the purge supply amount. Evaporative fuel supply control device. The purge supply amount changing means changes the purge supply amount to the minimum supply amount when the change in the fuel injection amount is predicted to be larger than the change in the purge supply amount and the concentration of the evaporated fuel is equal to or higher than a predetermined concentration. The fuel vapor supply control device for a lean burn internal combustion engine according to claim 1, wherein: The fuel supply apparatus further includes a fuel concentration change amount estimating unit for estimating that the change in the evaporated fuel concentration is larger than the change in the purge supply amount. 2. The purge supply amount is changed to the minimum supply amount when it is predicted that the change in the evaporated fuel concentration is larger than the change in the purge supply amount. An evaporative fuel supply control device for a lean burn internal combustion engine.

Images