JP4223580B2 - Fuel cut control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cut control device for an internal combustion engine that performs control for stopping the supply of fuel to the internal combustion engine during deceleration (hereinafter referred to as fuel cut or F / C) for the purpose of improving the fuel consumption rate. .
[0002]
[Prior art]
Conventionally, in an electronically controlled fuel injection control device for an internal combustion engine, when the throttle valve is fully closed and the engine speed is equal to or higher than a predetermined value, it is determined that the fuel supply is in an unnecessary deceleration state, and the fuel consumption rate In order to improve the fuel consumption, a fuel cut that temporarily stops fuel injection is performed.
[0003]
For example, Japanese Patent Laid-Open No. 8-148814 discloses an example of such a fuel cut control device. In this publication, by prohibiting the fuel cut during deceleration when the temperature of the catalyst provided in the exhaust system of the internal combustion engine is high, the catalyst is prevented from being exposed to a high-temperature lean atmosphere, thereby preventing deterioration of the catalyst. It has been proposed to do.
[0004]
[Problems to be solved by the invention]
By the way, in the apparatus described in the above publication, even in the same operating state, depending on the temperature of the catalyst, the fuel cut is executed and the fuel injection is stopped, and the fuel cut is prohibited and the fuel injection is stopped. There is a case where the vehicle continues, and the feeling of deceleration of the vehicle differs between the two. That is, when fuel cut is prohibited, the feeling of deceleration of the vehicle is impaired. Therefore, in such a conventional technique, such a deterioration in the feeling of deceleration gives the driver a feeling of strangeness.
[0005]
In view of such circumstances, an object of the present invention is to prevent the deterioration of the deceleration feeling of the vehicle when performing control for prohibiting fuel cut at the time of deceleration in order to prevent deterioration of the catalyst under conditions of a high temperature lean atmosphere. An object is to provide a fuel cut control device for an internal combustion engine.
[0006]
[Means for Solving the Problems]
In order to achieve the above objective, Clearly According to the present invention, fuel cut execution means for executing fuel cut when the internal combustion engine decelerates; Means for executing control for ensuring a minimum amount of intake air necessary for combustion in an operating state in which fuel cut is executed; In a fuel cut control device for an internal combustion engine, comprising: a fuel cut prohibiting means for prohibiting fuel cut by the fuel cut execution means when the temperature of a catalyst provided in an exhaust system of the internal combustion engine is high. Determining means for determining whether or not the engine is in an operating state in which the rate of contribution of the deceleration force of the internal combustion engine is high; and the determining means In And a canceling means for canceling the fuel cut prohibition by the fuel cut prohibiting means when it is determined that the operation state is present. The determination means determines that the vehicle is in the operating state when a speed smaller than a predetermined speed is selected in a transmission connected to the internal combustion engine. A fuel cut control device for an internal combustion engine is provided.
[0010]
The driving state in which the feeling of deceleration is impaired and the driver feels uncomfortable is a driving state in which the rate at which the deceleration force of the internal combustion engine contributes to the deceleration of the vehicle is high. The main structure constructed as described above. Clearly In such a fuel cut control device, the fuel cut prohibition based on the viewpoint of preventing catalyst deterioration is stopped and the fuel cut is executed under such an operating state, so that the deceleration force of the internal combustion engine increases, and the vehicle The deterioration of the feeling of deceleration is prevented.
[0012]
In particular When a small gear is selected in the transmission connected to the internal combustion engine In addition, It can be said that the ratio of the deceleration force of the internal combustion engine contributing to the deceleration of the vehicle is high. Main departure Clearly In such a fuel cut control device, the fuel cut prohibition based on the viewpoint of preventing catalyst deterioration is stopped when a speed smaller than a predetermined speed is selected in the transmission connected to the internal combustion engine, and the feeling of deceleration is deteriorated. Is prevented.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0015]
FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine equipped with a fuel cut control device according to an embodiment of the present invention. The engine 1 is an in-line four-cylinder four-cycle reciprocating gasoline engine mounted on a vehicle as an internal combustion engine. The engine 1 includes a cylinder block 2 and a cylinder head 3. In the cylinder block 2, a plurality of cylinders 4 extending in the vertical direction are arranged in parallel in the thickness direction of the paper surface, and in each cylinder 4, a piston 5 is accommodated so as to reciprocate. Each piston 5 is connected to a common crankshaft 7 via a connecting rod 6. The reciprocating motion of each piston 5 is converted into the rotational motion of the crankshaft 7 via the connecting rod 6.
[0016]
Between the cylinder block 2 and the cylinder head 3, the upper side of each piston 5 is a combustion chamber 8. The cylinder head 3 is provided with an intake port 9 and an exhaust port 10 for communicating both outer side surfaces and the combustion chambers 8 respectively. In order to open and close these ports 9 and 10, an intake valve 11 and an exhaust valve 12 are supported on the cylinder head 3 so as to be able to reciprocate substantially in the vertical direction. In the cylinder head 3, an intake side camshaft 13 and an exhaust side camshaft 14 are rotatably provided above the valves 11 and 12, respectively. Cams 15 and 16 for driving the intake valve 11 and the exhaust valve 12 are attached to the camshafts 13 and 14. Timing pulleys 17 and 18 provided at end portions of the camshafts 13 and 14 are connected to a timing pulley 19 provided at an end portion of the crankshaft 7 by a timing belt 20.
[0017]
That is, when the timing pulley 19 rotates as the crankshaft 7 rotates, the rotation is transmitted to the timing pulleys 17 and 18 via the timing belt 20. At that time, the rotation of the timing pulley 19 is transmitted to the timing pulleys 17 and 18 with the rotation speed reduced to ½. When the intake side camshaft 13 rotates with the rotation of the timing pulley 17, the intake valve 11 reciprocates due to the action of the cam 15, and the intake port 9 is opened and closed. When the exhaust camshaft 14 rotates with the rotation of the timing pulley 18, the exhaust valve 12 reciprocates due to the action of the cam 16, and the exhaust port 10 is opened and closed. Thus, the camshafts 13 and 14 are driven to rotate by the crankshaft 7, and the intake valve 11 and the exhaust valve 12 are opened and closed at a constant crank angle with a period of 720 °.
[0018]
An intake passage 30 including an air cleaner 31, a throttle valve 32, a surge tank 33, an intake manifold 34 and the like is connected to the intake port 9. Air outside the engine 1 (outside air) sequentially passes through the portions 31, 32, 33, and 34 of the intake passage 30 toward the combustion chamber 8. The throttle valve 32 is rotatably provided in the intake passage 30 by a shaft 32a. The shaft 32a is connected to an accelerator pedal (not shown) of the driver's seat via a wire or the like, and is rotated integrally with the throttle valve 32 in conjunction with the depression of the accelerator pedal by the driver. The amount of air flowing through the intake passage 30 (intake air amount) is determined according to the inclination angle of the throttle valve 32 at this time. The surge tank 33 is for smoothing the pulsation (pressure vibration) of the intake air. The idle adjustment passage 35 that bypasses the throttle valve 32 is provided with an idle speed control valve (ISCV) 36 for adjusting the air flow rate during idling.
[0019]
An injector 40 that injects fuel toward each intake port 9 is attached to the intake manifold 34. The fuel is stored in the fuel tank 41, pumped up from there by the fuel pump 42, and supplied to the injector 40 through the fuel pipe 43. An air-fuel mixture comprising fuel injected from the injector 40 and air flowing through the intake passage 30 is introduced into the combustion chamber 8 via the intake valve 11 in the intake stroke, and is compressed by the piston 5 in the compression stroke.
[0020]
In order to ignite this air-fuel mixture, a spark plug 50 is attached to the cylinder head 3. Upon ignition, the igniter 51 that has received the ignition signal controls energization and interruption of the primary current of the ignition coil 52, and the secondary current is supplied to the spark plug 50 via the ignition distributor 53. The ignition distributor 53 distributes the secondary current to the ignition plugs 50 of the respective cylinders in synchronization with the rotation of the crankshaft 7. The air-fuel mixture introduced into the combustion chamber 8 is exploded and combusted by ignition by the spark plug 50 (expansion stroke). The piston 5 is reciprocated by the high-temperature and high-pressure combustion gas generated at this time, the crankshaft 7 is rotated, and the driving force of the engine 1 is obtained.
[0021]
The combusted air-fuel mixture is guided to the exhaust port 10 through the exhaust valve 12 as exhaust gas in the exhaust stroke. Connected to the exhaust port 10 is an exhaust passage 60 including an exhaust manifold 61, a catalytic converter 62, and the like. In the catalytic converter 62, NO produced by the oxidation of HC (hydrocarbon) and CO (carbon monoxide), which are incomplete combustion components, and the reaction of nitrogen in the air and unburned oxygen. _x A three-way catalyst that simultaneously promotes the reduction of (nitrogen oxide) is accommodated. Thus, the exhaust gas purified by the catalytic converter 62 is discharged into the atmosphere.
[0022]
As shown in FIG. 1, the following various sensors are attached to the engine 1. A water temperature sensor 74 for detecting the temperature of the cooling water for the engine 1 (cooling water temperature THW) is attached to the cylinder block 2. An air flow meter 70 for detecting the intake air amount (flow rate QA) is attached to the intake passage 30. An intake air temperature sensor 73 for detecting the temperature of intake air (intake air temperature THA) is attached in the vicinity of the air cleaner 31 in the intake passage 30. In the intake passage 30, a throttle opening sensor 72 for detecting the rotation angle (throttle opening TA) of the shaft 32 a is provided in the vicinity of the throttle valve 32. When the throttle valve 32 is in the fully closed state, the idle switch 82 is turned on, and the throttle fully closed signal, which is the output thereof, becomes active. The surge tank 33 is provided with an intake pressure sensor 71 for detecting the internal pressure (intake pressure PM). In the middle of the exhaust passage 60, O for detecting the residual oxygen concentration in the exhaust gas. ₂ A sensor 75 is attached.
[0023]
The distributor 53 has a built-in rotor that rotates in synchronization with the rotation of the crankshaft 7. In order to detect the reference position of the crankshaft 7, the distributor 53 converts the crank angle (CA) to 720 based on the rotation of the rotor. A crank reference position sensor 80 for generating a reference position detection pulse for each CA is provided, and every 30 ° CA based on the rotation of the rotor to detect the rotational speed of the crankshaft 7 (engine rotational speed NE). A crank angle sensor 81 is provided for generating rotation speed detection pulses. The vehicle is provided with a vehicle speed sensor 83 that generates an output pulse for detecting the actual vehicle speed.
[0024]
An engine electronic control unit (engine ECU) 90 shown in FIG. 1 is a microcomputer system that executes fuel injection control, ignition timing control, idle rotation speed control, etc., and its hardware configuration is shown in the block diagram of FIG. It is. In accordance with a program and various maps stored in a read-only memory (ROM) 93, the central processing unit (CPU) 91 sends signals from various sensors and switches to an A / D conversion circuit (ADC) 95 or an input interface circuit 96. And the arithmetic processing is executed based on the input signal, and various actuator control signals are output via the drive control circuits 97a to 97c based on the calculation result. A random access memory (RAM) 94 is used as a temporary data storage location in the calculation / control process. Further, the backup RAM 99 is supplied with power by being directly connected to a battery (not shown), and stores data (for example, various learning values) that should be held even when the ignition switch is off. Used for. Each component in these ECUs is connected by a system bus 92 including an address bus, a data bus, and a control bus.
[0025]
In the ignition timing control, the engine state is comprehensively determined based on the engine rotation speed obtained from the crank angle sensor 81 and signals from other sensors, the optimum ignition timing is determined, and an igniter is set via the drive control circuit 97b. An ignition signal is sent to 51.
[0026]
In addition, the idle rotation speed control detects the idle state based on the throttle fully closed signal from the idle switch 82 and the vehicle speed signal from the vehicle speed sensor 83, and the target rotation speed determined by the engine coolant temperature from the water temperature sensor 74 and the like. By comparing the actual engine rotation speed and determining the control amount so as to reach the target rotation speed according to the difference, the ISCV 36 is controlled via the drive control circuit 97c to adjust the air amount. It maintains the idling speed.
[0027]
In this idle rotation speed control, learning control is performed together with the above-described feedback control in order to facilitate maintaining the idle rotation speed at a constant value. That is, the ISCV opening for maintaining the idle rotation speed at a constant value changes according to individual differences and changes with time of the parts. Therefore, the ISCV opening learning value DG for absorbing the difference is fed back. Learned and updated in the process of control.
[0028]
The fuel injection control basically calculates the fuel injection amount that achieves a predetermined target air-fuel ratio, that is, the injection time by the injector 40, based on the intake air amount per one rotation of the engine, and reaches a predetermined crank angle. The injector 40 is controlled via the drive control circuit 97a to inject fuel at the time. The intake air amount per one rotation of the engine is calculated from the intake air flow rate measured by the air flow meter 70 and the engine rotation speed obtained from the crank angle sensor 81, or the intake pipe obtained from the intake pressure sensor 71. Estimated by pressure and engine speed. When calculating the fuel injection amount, basic correction based on signals from the throttle opening sensor 72, the intake air temperature sensor 73, the water temperature sensor 74, and the like, O ₂ An air-fuel ratio feedback correction based on a signal from the sensor 75, an air-fuel ratio learning correction that makes the median of the feedback correction values the theoretical air-fuel ratio, and the like are added.
[0029]
The fuel injection control includes fuel cut control during deceleration. By the way, when the fuel cut is executed when the temperature of the catalyst (catalyst bed temperature) is high, the lean exhaust gas generated along with it flows into the catalyst, but it is known that the catalyst deteriorates under such a high temperature lean atmosphere. ing. Therefore, it has been conventionally proposed to prohibit fuel cut during deceleration according to the temperature of the catalyst. However, as described above, when fuel cut is prohibited and fuel injection is continued, the vehicle feels uncomfortable.
[0030]
In the present invention, in a driving state in which the feeling of deceleration is impaired and the driver feels uncomfortable, that is, in a driving state in which the deceleration force of the internal combustion engine (engine brake) contributes to the deceleration of the vehicle is high, the viewpoint of preventing catalyst deterioration. Do not ban fuel cuts based on. For example, when the traveling vehicle speed is low, the air resistance due to traveling wind is small, and it can be said that the vehicle is in an operating state in which the ratio of the deceleration force (engine brake) of the internal combustion engine to the deceleration of the vehicle is high. In the first embodiment of the present invention, when the vehicle speed is lower than a predetermined value, prohibition of fuel cut based on the viewpoint of preventing catalyst deterioration is stopped, and deterioration of the feeling of deceleration is prevented. Hereinafter, the specific process will be described in detail.
[0031]
FIG. 3 is a flowchart showing a processing procedure of a catalyst bed temperature estimation routine executed by the CPU 91 to estimate the catalyst bed temperature. This routine is executed at a predetermined cycle. The catalyst bed temperature can be estimated from the intake air flow rate QA. However, the catalyst bed temperature gradually changes with a certain delay time with respect to the change in the intake air flow rate. Therefore, the catalyst bed temperature is set to the delayed intake air flow rate DQA (delay QA) that reflects the change in the intake air flow rate QA with a delay of a certain time.
[0032]
First, in step 101, the current intake air flow rate QA is detected based on the output of the air flow meter 70. Next, in step 102, it is determined whether or not the current intake air flow rate QA is larger than the previously calculated intake air flow rate QAO. If so, the process proceeds to step 103, where the delayed intake air is delayed by a predetermined amount QAC. The flow rate DQA is increased. Otherwise, the routine proceeds to step 104, where the delayed intake air flow rate DQA is decreased by a predetermined amount QAD. Finally, in step 105, the QA calculated this time is stored as QAO for the next use. The delayed intake air flow rate DQA obtained in this way follows the intake air flow rate QA at a moderate speed and can be used as an amount reflecting the catalyst bed temperature. As a method for detecting the catalyst bed temperature, the temperature may be directly detected by a temperature sensor provided in the catalyst.
[0033]
FIG. 4 is a flowchart showing a processing procedure of a deceleration fuel cut execution control routine (first embodiment) executed by the CPU 91. This deceleration fuel cut execution control routine is most preferentially processed as one of the fuel injection controls, and determines whether or not the deceleration fuel cut should be executed at the next fuel injection timing. Is. This routine prohibits fuel cut during deceleration when the catalyst bed temperature is high, but further cancels fuel cut prohibition when the vehicle speed is lower than a predetermined value to prevent deterioration of the feeling of deceleration. Is.
[0034]
First, it is determined whether an idle-on F / C condition or a downhill F / C condition is satisfied as a fuel cut condition during deceleration (step 201). Here, the idle-on F / C condition refers to a condition that the idle switch 82 is on, that is, the throttle valve 32 is fully closed and the engine speed NE is equal to or higher than a predetermined value. The downhill F / C condition refers to a condition in which the intake air amount or the fuel injection amount falls below the combustion limit and misfire is likely to occur. When the determination result of step 201 is NO, that is, when the deceleration F / C condition is not satisfied, the flag XFC is set to 0 and the F / C non-execution state is set (step 205).
[0035]
On the other hand, when the determination result in step 201 is YES, that is, when the deceleration F / C condition is satisfied, it is determined whether or not the catalyst bed temperature equivalent amount DQA is smaller than a predetermined determination reference value DQAref (step 202). The determination reference value DQAref is a value corresponding to a catalyst bed temperature of 800 ° C., for example. When DQA <DQAref, that is, when the catalyst bed temperature is low, there is no possibility of catalyst deterioration due to the high temperature lean atmosphere, so the flag XFC is set to 1 to enter the F / C execution state (step 204).
[0036]
On the other hand, when DQA ≧ DQAref, that is, when the catalyst bed temperature is high, there is a risk of catalyst deterioration, and according to the prior art, the execution of F / C is prohibited. However, in the present embodiment, it is determined whether or not the vehicle speed SPD detected by the vehicle speed sensor 83 is greater than a predetermined determination reference value SPDref (step 203). When SPD> SPDref, i.e., when the vehicle speed is high, a large air resistance provides a comfortable deceleration. Therefore, in order to prevent F / C from the viewpoint of preventing catalyst deterioration, the flag XFC is set to 0 and the F / C A non-execution state is set (step 205). On the other hand, when SPD ≦ SPDref, that is, when the vehicle speed is low, deceleration due to air resistance cannot be obtained. Therefore, from the viewpoint of securing a feeling of deceleration, flag XFC is used to cancel F / C prohibition for preventing catalyst deterioration. 1 is set to the F / C execution state (step 204). The flag XFC operated in step 204 or 205 is referred to in separately executed fuel injection control. When XFC = 1, fuel injection is stopped.
[0037]
In the operation state where the fuel cut is executed, the intake air amount is set to a relatively large amount in order to reduce oil digestion due to the intake pipe negative pressure, but the combustion limit is not taken into consideration. Therefore, when fuel cut is prohibited, fuel is injected in a situation where the amount of intake air per stroke is below the combustion limit, resulting in a misfire and excessively increasing the temperature of the catalyst. Happens. That is, even though the fuel cut is prohibited to prevent the catalyst from deteriorating, it adversely affects the catalyst. Therefore, when prohibiting fuel cut during deceleration to prevent catalyst deterioration due to a high temperature lean atmosphere, it is necessary to secure an intake air amount that does not cause misfire in order to avoid such misfire. . Therefore, in this embodiment, the minimum amount of intake air necessary for combustion is ensured by using the ISCV 36 so that misfire does not occur no matter what time the fuel cut during deceleration is prohibited. Control is also executed at the same time.
[0038]
That is, in step 206 executed after step 204 or 205, a minimum intake air amount at which misfire does not occur is determined based on the current engine speed NE by referring to a map as shown in FIG. The opening DOPMINmap of ISCV 36 necessary for securing is obtained. Since the air amount per engine stroke at the combustion limit is a constant value, it is necessary to increase the intake air flow rate, which is the amount per unit time, as the engine speed NE increases. Therefore, the ISCV opening DOPMINmap is also set. It needs to be bigger. This map is stored in the ROM 73 in advance.
[0039]
Next, at step 207, it is determined whether or not the engine speed NE is greater than a predetermined determination reference value NEref. This determination reference value NEref is, for example, 1000 rpm. When NE ≦ NEref, this routine is terminated. On the other hand, when NE> NEref, based on DOPMINmap and the ISCV opening learning value DG that is learned to absorb individual differences and changes over time in the idle rotation speed control as described above,
DOPMIN ← DOPMINmap + DG
The lower limit guard value DOPMIN of the ISCV opening is calculated by executing the following calculation (step 208). In a separately executed process, the ISCV 36 is controlled so that the ISCV opening DOP does not fall below this DOPMIN.
[0040]
Next, a second embodiment of the present invention will be described. Even when a small gear is selected in the transmission connected to the internal combustion engine, it can be said that the ratio of the deceleration force (engine brake) of the internal combustion engine contributing to the deceleration of the vehicle is high. In the second embodiment, the fuel cut prohibition based on the viewpoint of preventing catalyst deterioration is stopped when a gear smaller than a predetermined gear (here, the third gear) is selected in the transmission connected to the internal combustion engine, The deterioration of the feeling of deceleration is prevented.
[0041]
FIG. 6 is a flowchart showing a processing procedure of a deceleration fuel cut execution control routine according to the second embodiment. Steps 301, 302, and 304 to 308 in this routine are the same as steps 201, 202, and 204 to 208 in the first embodiment. In the first and second embodiments, step 203 Only the content and the content of step 303 are different. That is, in step 303, it is determined whether or not the shift position of the transmission is, for example, 3rd speed or higher. When the shift position is 3rd speed or higher, it is determined that there is no sense of incongruity in deceleration, and F / C prohibition control based on the viewpoint of preventing catalyst deterioration is executed (step 305). On the other hand, when the shift position is less than the third speed, the F / C prohibition control for preventing catalyst deterioration is stopped from the viewpoint of securing a feeling of deceleration (step 304). In the above embodiment, for example, the third speed is used, but the present invention is not limited to this. Further, in a vehicle equipped with a continuously variable transmission, it is possible to change to a configuration in which it is determined in step 303 whether or not the transmission gear ratio is greater than or equal to a predetermined gear ratio that affects the feeling of deceleration.
[0042]
Next, a third embodiment of the present invention will be described. When the transmission connected to the internal combustion engine is in the neutral state, it can be said that the driver is in an operating state where the driver expects an early decrease in the rotational speed of the internal combustion engine. In the third embodiment, when the transmission connected to the internal combustion engine is in the neutral state, the fuel cut prohibition based on the viewpoint of preventing catalyst deterioration is stopped, so that the driver does not feel uncomfortable.
[0043]
FIG. 7 is a flowchart showing a processing procedure of a deceleration fuel cut execution control routine according to the third embodiment. Steps 401, 402, and 404 to 408 in this routine are the same as steps 201, 202, and 204 to 208 in the first embodiment. In the first and third embodiments, step 203 Only the contents and the contents of step 403 are different. That is, in step 403, it is determined whether or not the shift position of the transmission is neutral. When the shift position is not neutral, F / C prohibition control based on the viewpoint of preventing catalyst deterioration is executed (step 405). On the other hand, when the shift position is neutral, the F / C prohibition control for preventing catalyst deterioration is stopped from the viewpoint of preventing uncomfortable feeling (step 404).
[0044]
【The invention's effect】
As described above, according to the present invention, in a driving state in which the feeling of deceleration is impaired and the driver feels uncomfortable, that is, in a driving state in which the ratio of the deceleration force of the internal combustion engine to the deceleration of the vehicle is high, The fuel cut prohibition based on the viewpoint of preventing catalyst deterioration under a high temperature lean atmosphere is stopped and the fuel cut is executed, so that the deceleration force of the internal combustion engine is increased and the deterioration of the vehicle deceleration feeling is prevented.
[Brief description of the drawings]
FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine equipped with a fuel cut control device according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a hardware configuration of an engine ECU.
FIG. 3 is a flowchart showing a processing procedure of a catalyst bed temperature estimation routine executed by a CPU.
FIG. 4 is a flowchart showing a processing procedure of a deceleration fuel cut execution control routine (first embodiment) executed by a CPU.
FIG. 5 is a diagram showing a map in which an ISCV opening degree DOPMINmap necessary for securing a lower limit intake air amount at which misfire does not occur is determined in accordance with an engine speed NE.
FIG. 6 is a flowchart showing a processing procedure of a deceleration fuel cut execution control routine (second embodiment) executed by a CPU.
FIG. 7 is a flowchart showing a processing procedure of a deceleration fuel cut execution control routine (third embodiment) executed by a CPU.
[Explanation of symbols]
1 ... Inline 4-cylinder 4-cycle reciprocating gasoline engine
2 ... Cylinder block
3 ... Cylinder head
4 ... Cylinder
5 ... Piston
6 ... Connecting rod
7 ... Crankshaft
8 ... Combustion chamber
9 ... Intake port
10 ... Exhaust port
11 ... Intake valve
12 ... Exhaust valve
13 ... Intake side camshaft
14 ... Exhaust camshaft
15 ... Intake side cam
16 ... Exhaust side cam
17, 18, 19 ... Timing pulley
20. Timing belt
30 ... Intake passage
31 ... Air cleaner
32 ... Throttle valve
32a ... Throttle valve shaft
33 ... Surge tank
34 ... Intake manifold
35 ... Idle adjust passage
36 ... Idle rotation speed control valve (ISCV)
40 ... Injector
41 ... Fuel tank
42 ... Fuel pump
43 ... Fuel piping
50 ... Spark plug
51 ... igniter
52 ... Ignition coil
53 ... Ignition distributor
60 ... Exhaust passage
61 ... Exhaust manifold
62 ... Catalytic converter
70 ... Air flow meter
71 ... Intake pressure sensor
72 ... Throttle opening sensor
73 ... Intake air temperature sensor
74 ... Water temperature sensor
75 ... O ₂ Sensor
80 ... Crank reference position sensor
81 ... Crank angle sensor
82 ... Idle switch
83 ... Vehicle speed sensor
90 ... Engine ECU
91 ... CPU
92 ... System bus
93 ... ROM
94 ... RAM
95 ... A / D conversion circuit
96 ... Input interface circuit
97a, 97b, 97c ... drive control circuit
99 ... Backup RAM

Claims (1)

And fuel cut means during deceleration of the internal combustion engine to execute the fuel cut, in the operating condition where fuel cut is executed and means for executing a control to ensure the minimum required amount of intake air into the combustion exhaust of the internal combustion engine a fuel cut control apparatus for an internal combustion engine having a fuel cut prohibiting means for prohibiting fuel cut by the fuel cut means when the temperature of the catalyst provided in the system is high, the deceleration of the internal combustion engine to the deceleration of the vehicle a determination unit configured to determine whether the force ratio contributes at a high operating state, stop means to stop the fuel cut prohibition by said fuel cut prohibiting means when it is determined that more are in the operating condition in said determination means And the determination means determines that the vehicle is in the operating state when a gear smaller than a predetermined gear is selected in a transmission connected to the internal combustion engine. Wherein, the fuel cut control apparatus for an internal combustion engine.

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