EP1160437A2

EP1160437A2 - Control apparatus and method of internal combustion engine

Info

Publication number: EP1160437A2
Application number: EP01113403A
Authority: EP
Inventors: Yasushi Ito
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 2000-06-02
Filing date: 2001-06-01
Publication date: 2001-12-05
Also published as: EP1160437A3; JP2001342878A

Abstract

A control apparatus of an internal combustion engine for performing fuel cut control for suspending fuel supply to the internal combustion engine during the operation, comprising at least any one of means for controlling immediately before the fuel cut control to control the torque from the internal combustion engine to driving wheels in a power transmission system from the internal combustion engine to the driving wheels in the decrease direction, immediately before performing the fuel cut control, in case when the fuel cut control execution is determined (steps S5, S6), and means for controlling immediately after the fuel cut control to control the torque from the internal combustion engine to the driving wheels in the power transmission system from the internal combustion engine to the driving wheels in the increase direction, immediately after performing the fuel cut control, in case when the fuel cut control is executed.

Description

BACKGROUND OF THE INVENTION 1.Field of the invention

The invention relates to a control apparatus and method for an internal combustion engine for outputting power by fuel combustion such as gasoline engine and, especially, it relates to a control apparatus and method for executing the fuel cut control for stopping fuel supply during the operation in order to improve the fuel efficiency.

2.Description of Related Art

In the internal combustion engine such as gasoline engine, it is necessary to start from the stop state by forced rotation through external force of an electric motor or the like. However, in case of coasting where the vehicle travels by inertia force as during the deceleration, the engine is rotated by force through external force, so the fuel supply is stopped to improve the fuel efficiency. This is so-called fuel cut control.

The fuel cut control is performed within the revolution range when the engine can maintain its autonomic rotation, by resuming the fuel supply. In other words, the fuel supply is cut until the engine revolution reduces to the return revolution during the deceleration. Here, if the engine revolution is controlled not to drop to its return revolution, the fuel supply suspension time period will be prolonged, and the fuel efficiency improvement effect will be enhanced. Therefore, conventionally, the engine revolution is prevented from lowering due to so-called sliding in the power transmission system, by setting the power transmission system from engine to driving wheels near a so-called mechanical direct coupling state. An embodiment thereof is a control for relatively increasing the engine revolution during the deceleration, by engaging a lockup clutch (direct coupling clutch) in a fluid torque transfer such as torque converter.

However, since the lockup clutch is an apparatus for mechanically connecting an input side member and an output side member in place of a fluid, the torque variation is transmitted as it is. Therefore, for example, when the engine revolution lowers to the so-called return revolution to resume the fuel supply, the engine forced to rotate by external force starts autonomic rotation by fuel combustion, in short, it starts outputting torque, thereby changing suddenly the torque effect state to the power transmission system from engine to driving wheels from so-called negative torque applied state to the positive torque application state. When such a sudden torque variation occurs with the lockup clutch completely engaged, this torque variation is transmitted to the vehicle as it is and may be felt sometimes as a shock. In the related art, in order to solve such inconvenience, the invention described in Japanese Utility Model Application Laid-open No. 5-27249 is devised to control the lockup clutch to the half-clutch state immediately before the engine revolution lowers to the return revolution, and to absorb torque variation by sliding in the lockup clutch.

The fuel cut control mentioned above is performed when the throttle valve is closed in the normal driving state upon completion of engine idling or the like, and the engine revolution is equal or superior to the predetermined revolution. To be more specific, the fuel supply is suspended based on the fact that the throttle opening is closed to about the idle opening or so, or the accelerator pedal is released. Therefore, the engine operation state changes from the driving state that was outputting power to the driven state where the engine is forced to rotate by external force. Therefore, the torque action state changes in the power transmission system by performing the fuel cut control, and this may cause a shock or vibration.

In the invention described in the aforementioned publication, the lockup clutch is controlled to the half-clutch state during the return from the fuel cut control; here, if the lockup clutch transmission torque capacity is lowered, the power forcing the engine to rotate lowers, the engine revolution drops and, therefore, the return from fuel cut control becomes earlier, reducing the fuel cut period. Further, if such lockup clutch release direction control is performed when the fuel cut control starts, the engine revolution lowers making sometimes impossible to perform the fuel cut control that ought to be performed. Thus, the invention described in the aforementioned publication concerns the control during the return from the fuel cut control, and problems occur in the practice, if it is used when the fuel cut control starts.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a control apparatus and method allowing to prevent shock or vibration from occurring when fuel cut control starts.

According to a first aspect of the invention, a control apparatus of an internal combustion engine for performing fuel cut control for suspending fuel supply to the internal combustion engine during the operation is characterized by comprising at least any one of means for controlling immediately before the fuel cut control to control the torque from the internal combustion engine to driving wheels in a power transmission system from the internal combustion engine to the driving wheels in the decrease direction, immediately before performing the fuel cut control, in case when the fuel cut control execution is determined, and means for controlling immediately after the fuel cut control to control the torque from the internal combustion engine to the driving wheels in the power transmission system from the internal combustion engine to the driving wheels in the increase direction, immediately after performing the fuel cut control, in case when the fuel cut control is executed.

Therefore, in case where the execution of fuel cut control for suspending fuel supply to the internal combustion engine during the operation is determined, the torque from the internal combustion engine to the driving wheels is decreased immediately before performing that fuel cut control. As the result, the torque directed to the driving wheel has been already decreased somehow, at the moment when the output torque of the internal combustion engine decreases according to the fuel cut control execution, reducing a variation range of driving wheel torque in case when the torque decreases according to the fuel cut control execution. Besides, when the means for controlling immediately after the fuel cut control is provided, since control to increase the torque directed to the driving wheels in the power transmission system immediately after performing the fuel cut control is executed, the output torque of the internal combustion engine and the torque increase due to the means for controlling immediately after the fuel cut control cancel the torque variation amount, and as the result, reduce a variation range of the torque in the driving wheel or power transmission system torque even when the output torque of the internal combustion engine decreases according to the fuel cut control execution.

The means for controlling immediately before the fuel cut generating such effects can be means for reducing air intake amount to the internal combustion engine, while the means for controlling immediately after the fuel cut control can be means for increasing air intake amount to the internal combustion engine.

Here, a throttle valve can be adopted as the means for reducing or increasing air intake amount.

Otherwise, means for reducing an opening of another valve for controlling the amount of the air inhaled bypassing the throttle valve can be adopted as the means for reducing or increasing air intake amount. An example of this another valve is an idle speed control valve.

Therefore, according to these aspects, since the amount of the air inhaled into the internal combustion engine as mixed air with fuel immediately before execution of the fuel cut control decreases, the output torque of the internal combustion engine decreases. The torque variation range reduces even when the torque directed to the driving wheel decreases according to the fuel cut control, by performing the fuel cut control in this state. On the other hand, when the intake air amount is controlled immediately after performing the fuel cut, since the amount of the air inhaled as a single substance into the internal combustion engine immediately after performing the fuel cut control, the negative work amount by the internal combustion engine or pumping loss decreases and, as the result, the reduction of the output torque of the internal combustion engine is controlled, and the output torque increased relatively. Therefore, even when the fuel supply to the internal combustion engine is suspended, the negative work amount generated immediately after that is controlled, thereby reducing the variation range of the output torque of the internal combustion engine. In other words, the variation range of the torque directed to the driving wheel in the power transmission system is reduced.

On the other hand, in the aforementioned first aspect, the internal combustion engine may be a reciprocating type internal combustion engine having a piston reciprocating in the cylinder and comprises an intake valve for opening/closing an intake port of the cylinder according to the piston motion, and the means for controlling immediately before the fuel cut control and means for controlling immediately after the fuel cut control may be means for changing the intake valve closing timing in a direction decreasing the air intake amount in the cylinder.

In this aspect, "means for changing in a direction decreasing the air intake amount in the cylinder" is means for delaying the valve closing timing in case when for example the intake valve closes after an intake bottom dead center and, on the contrary, it is means for advancing the valve closing timing in case when the intake valve closes before the intake bottom dead center. Therefore, in case when the intake valve is closed after the intake bottom dead center immediately before performing the fuel cut control, a part of air inhaled into the cylinder is pushed back from the intake port and discharged from the cylinder by a relative delay, while in case when the valve is closed before the intake bottom dead center, the air intake is suspended by the advancement, and as the result, in both cases, the amount of the air substantially inhaled into the cylinder decreases, lowering the output torque of the internal combustion engine. Consequently, the torque directed to the driving wheel in the power transmission system immediately before performing the fuel cut control decreases, and as the fuel cut control is performed in this state, thereby reducing the variation range of the output torque of the internal combustion engine even when the output torque of the internal combustion engine lowers according to the execution of fuel cut control.

In addition, after the execution of fuel cut control, in case when the intake closing timing closes the valve after the intake bottom dead center in the state of suspending fuel supply, a part of air inhaled into the cylinder is pushed back from the intake port and discharged from the cylinder by a relative delay, weakening the intake pipe negative pressure, while in case when the valve is closed before the intake bottom dead center, the air intake is suspended by the advancement, weakening the intake pipe negative pressure, and as the result, in both cases, the negative work amount by the internal combustion engine is controlled. That is, the decrease of the output torque of the internal combustion engine is restrained, thereby increasing relatively the output torque. Consequently, even when the fuel supply to the internal combustion engine is suspended, the negative work amount generated immediately after that is restrained, thereby reducing the variation range of the output torque of the internal combustion engine. In other words, the variation range of the torque directed to the driving wheel in the power transmission system is reduced.

In addition, in the aforementioned first aspect, an operation member for receiving torque from the power transmission system is further provided, and the means for controlling immediately before the fuel cut control may be means for reducing the torque of the power transmission system by increasing the torque to be input into the operation member, and moreover, the means for controlling immediately after the fuel cut control may be means for relatively increasing the torque of the power transmission system by decreasing the torque to be input into the operation member.

As such operation member, auxiliary equipment coupled to the internal combustion engine may be adopted, and the means for controlling immediately before the fuel cut control may be means for increasing the driving torque of the auxiliary equipment, while the means for controlling immediately after the fuel cut control may be means for decreasing the driving torque of the auxiliary equipment.

Consequently, in these aspects, the torque directed to the driving wheel from the internal combustion engine is reduced by increasing the torque to be input into the operation member such as auxiliary equipment, immediately before the fuel cut control and, as the result, the variation range of the torque in the driving wheel or power transmission system is reduced, even when the output torque of the internal combustion engine lowers according to the execution of fuel cut control. In addition, the torque directed to the driving wheel from the internal combustion engine is increased relatively by reducing the torque to be input into the operation member such as auxiliary equipment, immediately after the fuel cut control and, as the result, the variation range of the torque in the driving wheel or power transmission system is reduced even when the output torque of the internal combustion engine lowers according to the execution of fuel cut control.

Further, in the aforementioned respective aspects, the power transmission system may include a torque transmission variable mechanism for changing the torque transmission efficiency between the internal combustion engine and the driving wheels and, at the same time, may include further a torque transmission variable control means for setting this torque transmission variable mechanism in a state where the torque transmission efficiency becomes relatively high before and after performing the fuel cut control.

Consequently, even in a state where the internal combustion engine and the driving wheel are coupled more firmly, the variation range of the torque directed to the driving wheel in the power transmission system by the change of the output torque of the internal combustion engine according to the execution of fuel cut control is restricted.

According to a second aspect of the invention, a control method of an internal combustion engine for performing fuel cut control for suspending fuel supply to the internal combustion engine during the operation is characterized by comprising at least any one of step for controlling the torque from the internal combustion engine to driving wheels in a power transmission system from the internal combustion engine to the driving wheels in the decrease direction, immediately before performing the fuel cut control, in case when the fuel cut control execution is determined, and step for controlling the torque from the internal combustion engine to the driving wheels in the power transmission system from the internal combustion engine to the driving wheels in the increase direction, immediately after performing the fuel cut control, in case when the fuel cut control is executed.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a flow chart showing an embodiment of a control according to the invention;

Fig. 2 is a time chart schematically showing the change of the output torque in case of executing the control of Fig. 1;

Fig. 3 is a flow chart showing another embodiment of control according to the invention;

Fig. 4 is a flow chart showing still another embodiment of control according to the invention;

Fig. 5 is a time chart schematically showing the output torque change in case of executing the control shown in Fig. 4;

Fig. 6 is a flow chart showing another embodiment of control according to the invention;

Fig. 7 is a flow chart showing still another embodiment of control according to the invention;

Fig. 8 is a diagram schematically showing an embodiment of a power transmission system of a vehicle loaded with the internal combustion engine to be object of the invention; and

Fig. 9 is a view schematically showing the coupling relation of intake and exhaust system and auxiliary equipment for the internal combustion engine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments of the invention will be described. The internal combustion engine, object of the invention, is a power apparatus outputting power by fuel combustion such as gasoline or diesel engine, and as an example, is an internal combustion engine loaded to a vehicle and used mainly as power source for travel. Fig. 8 shows schematically a power transmission system of an embodiment wherein an internal combustion engine (E/G) 1 is used as vehicle power source, and an output shaft of an internal combustion engine 1 is coupled to a transmission 2.

The transmission 2 shown here is composed by coupling a transmitting mechanism following a fluid type torque transfer, and this fluid type torque transfer is composed, as an example, of a torque converter 4 provided with a lockup clutch 3. That is, the torque converter 4, as known conventionally, is composed to rotate a turbine runner by affording oil spiral flow generated by a pump impeller to the turbine runner, and to control the flow direction of oil returning from the turbine runner to the pump impeller by a stator, and to transmit torque through oil. On the other hand, the lockup clutch 3 is disposed between an input side member to which the pump impeller is coupled and communicated and an output side member to which the turbine runner is coupled, and composed to transmit torque by mechanically engaging an input element and an output element by friction force or the like. Their engagement/release is controlled, for instance, by hydraulic pressure.

Therefore, in a state where the lockup clutch 3 is released, torque is transmitted through the torque converter 4. However, an inevitable sliding is generated since the torque converter 4 is composed to transmit torque through a fluid, and the torque transmission efficiency never attains 100%. On the other hand, since the lockup clutch 3 is composed to transmit torque by mechanical engagement, in a complete engagement state, the torque transmission efficiency becomes 100% or so, a torque transmission efficiency higher than the torque transmission efficiency through the torque converter 4. That is, the torque transmission efficiency varies higher or lower according to the engagement/release state of the lockup clutch 3 and, therefore, the lockup clutch 3 and the torque converter 4 compose the torque transmission variable mechanism in the invention.

Besides, the transmission is a mechanism composed so as to change the gear ratio by operating with driving force provided by an actuator to be controlled by artificial operation force or electrically, and belt type or toroidal type continuous transmission mechanism or gear type step transmission can be used. In the embodiment shown in the drawing, a continuous variable transmission (CVT) 5 is adopted, the gear ratio changes continuously, making the output torque variation due to change gear smoother and, thereby, allowing maintaining the lockup clutch 3 in the engagement state, until the revolution of the internal combustion engine 1 becomes considerably low.

An output shaft of the aforementioned transmission 2 is connected to right and left driving wheels 7 through a propeller shaft and a final reduction gear 6. It can also be composed to control the driving torque in the reduction direction, by attaching a brake (not shown) for driving torque control (traction control) or for antilock brake system (ABS) to all wheels including the driving wheels 7.

A reciprocating type engine is the most popular as the aforementioned internal combustion engine 1, and the embodiment shown in the drawing is composed to control electrically fuel supply/suspension or air intake amount and valve timing and further driving torque of auxiliary equipment or the like. Referring to drawings, in Fig. 9, a piston 9 moving up and down in a cylinder 8 is provided, and it is composed to output power by converting its vertical movement into rotational movement by a crank mechanism. An intake port 10 and an exhaust port 11 are provided in the upper section of this cylinder 8 and it is composed to open/close the intake port 10 by an intake valve 12 and to open/close the exhaust port 11 by an exhaust valve 13. These intake valve 12 and exhaust valve 13 are composed to open/close according to the rotation angle of a crankshaft (not shown), namely together with the piston 9.

And, a variable valve timing mechanism (VVT) 14 for controlling to relatively delay or advance their opening/closing timing, especially the intake valve 12 opening/closing timing is provided. As an example, it is composed to delay or advance the opening/closing timing by changing an attachment phase of a cam (not shown) pressing the

valves

12, 13 with respect to a cam shaft (not shown) or by changing a relative phase of a cam shaft and a pulley driving the same (respectively not shown).

A throttle valve 16 for controlling the intake amount is arranged in the middle of a intake pipe 15 communicating with the intake port 10. This throttle valve 16 is a valve for changing the opening according to the acceleration/deceleration demand by the accelerator operation or the like, and in the illustrated embodiment, an electronic throttle valve 16 to be opened/closed by an electrically controlled actuator 17 is adopted. Therefore, in the embodiment shown here, the throttle opening can be controlled independently of the accelerator operation, and it is composed to control an idle revolution (idle speed) by the electronic throttle valve 16.

In case where the throttle valve is composed to be opened/closed according only to the accelerator operation, an idle speed control valve (ISC valve) 18 controlling the air amount to intake by bypassing this throttle valve. In this case, it can be composed to control electrically the intake air amount by controlling the opening of this ISC valve 18 by an actuator 19 such as electric motor. Moreover, a fuel injector 20 is provided in the vicinity of the aforementioned intake port 10, for producing the mixture by injecting fuel into the intake air.

An engine-electronic control unit (E-ECU) 21 is provided for controlling opening/closing timing of the intake valve 12 and exhaust valve 13, opening of the throttle valve 16, opening of the ISC valve 18, fuel injection amount and injection execution/suspension by the fuel injector 20 or further ignition period or the like in the aforementioned internal combustion engine 1. This engine-electronic control unit 21 is mainly composed of a microcomputer and is composed to calculate using input data or previously stored data and output a predetermined control command signal. This engine-electronic control unit 21 includes an revolution NE of the internal combustion engine 1, vehicle speed and accelerator opening (operation amount of an accelerator pedal (not shown)) Acc and a cooling water temperature of the internal combustion engine 1 and engagement/release (ON/OFF) signal of the aforementioned lockup clutch (L/U) 3 input as data.

In addition, an transmission-electronic control unit (T-ECU) 22 for controlling engagement/release of the lockup clutch 3 in the transmission 2 or the gear ratio to be set by the continuous variable transmission 5. This transmission-electronic control unit 22 is mainly composed of a microcomputer and is composed to calculate using input data or previously stored data and output a predetermined control command signal to the transmission 2. To be more specific, control signals of gear ratio or engagement/release of the lockup clutch 3 are output based on the driving demand amount shown by the accelerator opening and the like or the driving status shown by the vehicle speed or the like. These

electronic control units

21, 22 are connected with each other allowing data exchange with each other.

Auxiliary equipment such as a compressor 23 for air conditioner or alternator 24 is coupled to an output shaft (crankshaft) of the internal combustion engine 1 trough a contact transmission mechanism such as belt. The auxiliary equipment is driven as necessary and, for example, the power transmission system to the compressor 23 for air conditioner is provided with a clutch (not shown), for transmitting the output torque of the internal combustion engine 1 to the compressor 23 for air conditioner by engaging this clutch when it is required to cool the inside of the cabin. In case of using a variable capacity type compressor 23 for air conditioner, its capacity is to be modified according to the cooling requirement amount. Consequently, the torque directed to the driving wheel from the internal combustion engine 1 increases or decreases by driving the auxiliary equipment and changing its driving torque. Here, an electronic control unit (not shown) for auxiliary equipment control is provided and connected allowing data exchange with the aforementioned respective

electronic control units

21, 22.

A system is provided for executing the fuel cut control for momentarily suspending fuel supply, when a predetermined condition is met during the operation, in order to reduce fuel consumption of the aforementioned internal combustion engine 1. To be more specific, the engine-electronic control unit 21 determines to execute the fuel cut control, and fuel supply from the fuel injector 20 is suspended by a command signal based on this determination result. Here, this fuel cut control execution is determined when, for example, idling of the internal combustion engine 1 is completed, its cooing water temperature is equal or superior to a predetermined temperature and the accelerator opening becomes zero in a state where the revolution NE of the internal combustion engine 1 is equal or superior to a predetermined revolution. The fuel supply restarts when the revolution NE of the internal combustion engine 1 becomes equal or inferior to the predetermined revolution according to the vehicle speed down.

Execution of this fuel cut control causes the output torque of the internal combustion engine 1 to decrease, and therefore, in case where the torque transmission rate in the power transmission system from the internal combustion engine 1 to the driving wheel 7 is high, in short, in case where the lockup clutch 3 is engaged and the coupling state of the internal combustion engine 1 and the driving wheel 7 becomes so-called a rigid state, the fuel cut control execution may suddenly change the driving torque and provoke a shock. Therefore, the control apparatus related to the invention mainly composed of the aforementioned transmission-electronic control unit 22 for the internal combustion engine 1 is composed to execute the following control immediately before or after performing the fuel cut control.

Fig. 1 is a flow chart showing an embodiment of a control thereof, and the control embodiment shown here is applied to the internal combustion engine 1 composed to control the idle speed by the electronic throttle valve 16. A routine shown by the flow chart of Fig. 1 is executed every predetermined time (several tens of microseconds) Δt. Now, the embodiment shown in the flow chart of Fig. 1 is described more concretely. First, it is determined whether the idle switch is ON or not (step S1). This idle switch is turned ON when the accelerator pedal is released, or when its step-on amount becomes zero and, therefore, idling state or not is determined in the step S1.

If the determination of the step S1 is affirmative according to the fact that the idle switch in ON, an opening which corresponds to the intake air amount required for maintaining the idle speed or idle speed control opening isc is set as provisory target opening tt of the electronic throttle valve 16 (step S2). Here, this idle speed control opening isc is a predetermined value, or an established value updated by learning control.

Next, it is determined whether the flag before performing the fuel cut control is ON or not (step S3). In other words, it is determined whether it is the time immediately before suspending fuel supply to the internal combustion engine 1 during the operation or not. As mentioned above, the fuel cut control is performed when the accelerator release and, moreover, other conditions are satisfied. Therefore, if any one of these conditions is not met, it is not determined to execute the fuel cut control, and the flag before performing the fuel cut control shall not be turned ON. In addition, the flag before performing the fuel cut control shall not be turned ON in case other than immediately before performing the fuel cut, for example, when the fuel cut control has already executed.

If the determined of the step S3 is affirmative according to the fact that the fuel cut control execution is determined and this control has not been executed yet, it is determined whether the lockup flag is ON or not (step S4). This lockup flag is turned ON in case where the lockup clutch 3 is in engaged state, or in case where the internal combustion engine 1 and the driving wheel 7 are coupled rigidly and the torque transmission efficiency in the driving system is high, and is switched ON/OFF by a predetermined routine executed by the transmission-electronic control unit 22.

If the determination of the step S4 is affirmative according to the fact that the lockup clutch 3 is engaged, an opening fcp before performing fuel cut control when lockup ON is set as provisory target opening tt of the electronic throttle valve 16 (step S5). Here, this opening fcp before performing fuel cut control when lockup ON is an opening smaller than the aforementioned idle speed control opening isc (fcp < isc) and, therefore, is an opening reducing the intake air amount than during the idling. Thus set provisory target opening tt is set as target throttle opening t (step S6), and the opening of the electronic throttle valve 16 is controlled to be this target opening t. Consequently, after establishment of fuel cut control execution determination, in a state immediately before the execution thereof, the throttle opening is limited to an opening smaller than the opening for maintaining the idle speed, provided that the lockup clutch 3 is engaged. As the result, the intake air amount in a state where fuel is supplied to the internal combustion engine 1 reduces, lowering the output torque of the internal combustion engine 1.

In the state immediately before performing the fuel cut control, the process from the aforementioned steps S1 to S6 is performed every predetermined time Δt and a state where the intake air amount is limited, or a state where the output torque of the internal combustion engine 1 is lowered is sustained. Then, when it comes to the time point to perform the fuel cut control when a predetermined time has elapsed after the establishment of fuel cut control execution determination, the aforementioned flag before performing the fuel cut control is turned OFF, and the determination of the aforementioned step S3 becomes negative. In this case, it advances to the step S6 skipping the steps S4 and S5, and the idle speed control opening isc being set as provisory target throttle opening tt, it is set as target throttle opening t, and the actual throttle opening is controlled to be this target throttle opening t. In other words, the throttle opening is set to an opening maintaining the normal idle speed. Therefore, in the internal combustion engine 1, as air is inhaled and exhausted with fuel supply suspended, a torque accompanying a so-called pumping loss is generated as braking torque (engine brake torque).

The change of the output torque TE of the internal combustion engine 1 in case of the aforementioned decrease control of intake air amount immediately before performing the fuel cut control is shown as in Fig. 2. In short, if the accelerator opening Acc becomes zero at the time point t0, the flag before performing the fuel cut control is turned ON at this time point, provided that idling of the internal combustion engine 1 is completed, and the revolution NE of the internal combustion engine 1 is equal or greater than the predetermined revolution. As the result, the throttle opening is controlled taking the opening fcp before performing fuel cut control when lockup ON as target throttle opening t, the output torque TE of the internal combustion engine 1 becomes a torque shown by the solid line in Fig. 2 lower than the idling time torque shown by the broken line.

Then, fuel supply to the internal combustion engine 1 is suspended by the execution of fuel cut control at the time point t1 when a predetermined time has elapsed from establishment of fuel cut control execution determiation and, at the same time, the throttle opening is controlled taking the idle speed control opening isc as target. As the result, the output torque TE of the internal combustion engine 1 becomes a negative torque turned by the vehicle travel inertia force.

Therefore, according to the aforementioned control, when the fuel cut control is to be executed, the output torque TE of the internal combustion engine 1 is lowered previously to a torque lower than the idling time torque, and the output torque TE of the internal combustion engine 1 becomes still lower (increase in the negative direction) by suspending the fuel supply in this state, making the aforementioned variation range of the torque directed to the driving wheel 7 from the internal combustion engine 1 in the power transmission system is reduced. This will be described referring to Fig. 2. When the aforementioned intake air amount reduction control is not performed, the torque reduces from the idling time output torque shown by the broken line in Fig. 2 to the fuel cut control time torque. However, when the aforementioned intake air amount reduction control is performed, the torque reduces from a torque smaller than the idling time output torque to the fuel cut control time torque, the variation range of driving torque is reduced by the torque reduced according to the intake air amount reduction control. Consequently, the torque variation according to the execution of fuel cut control is restrained, mitigating or preventing the shock.

In case where the determination is negative in the step S4 by the fact that the lockup clutch 3 is released, it advances immediately to the step S6, and the control to lower the output torque of the internal combustion engine 1 or control to reduce temporally the throttle opening is not performed. Because, in the state where the lockup clutch 3 is released, the aforementioned torque transmission efficiency of the power transmission system is low, therefore, the vehicle inertia force is not transmitted sufficiently to the internal combustion engine 1, the internal combustion engine 1 revolution lowers, and in an extreme case, engine stall may occur.

Further, the determination is negative in the step S1 by the fact of being out of idling state, a normal throttle opening control is executed (step S7). In short, the throttle opening is determined based on the output target torque and the internal combustion engine 1 revolution (engine speed), and set as provisory target opening tt. Thereafter, it advances to the step S6.

Here, the aforementioned control embodiment is an example applied to an internal combustion engine 1 composed to control the idle speed by the electronic throttle valve 16. However, in an internal combustion engine 1 composed to control the idle speed by the aforementioned ISC valve 18, the intake air amount reduction control immediately before performing the fuel cut control is performed by temporally reducing the ISC valve 18 opening. This control can be represented, as an example, by a control routine wherein the throttle opening in the control embodiment shown in Fig. 1 is substituted with the ISC valve opening.

On the other hand, the control to lower temporally the output torque by reducing the intake air amount can also be performed by differentiating the valve closing period of the intake valve 12 from the idling time valve closing time, other than the opening restriction of the electronic throttle valve 16 or ISC valve 18 mentioned above. Fig. 3 is a flow chart showing this embodiment of control.

The routine shown in Fig. 3 is executed every predetermined short time Δt, and first, it is determined whether the idle switch is ON or not (step S11). This is a control similar to the step S1 shown in Fig. 1. If the determination of the step S11 is affirmative according to the fact being in the idle state, an idle time valve timing Tvi is set as provisory target valve timing Tvtt (step S12). Here, this idle time valve timing Tvi is a predetermined time in connection with the crank angle or a stroke position of the piston 9.

Next, it is determined whether the flag before performing the fuel cut control is ON or not (step S13) and if the lockup flag is ON or not (step S14) consecutively. These determinations are similar to the determination process of steps S3 and S4 shown in Fig. 1 mentioned above. If the determinations of these steps S13 and S14 are affirmative, a valve timing TVfcp before performing the fuel cut control in lockup ON time is set as provisory target valve timing Tvtt (step S15). This valve timing TVfcp before performing the fuel cut control in lockup ON time is a timing delayed than the idling time valve closing period, in case when the variable valve timing mechanism 14 is used to control the valve closing period of the intake valve 12 after the time when the piston 9 attained the intake bottom dead center. Moreover, the valve timing TVfcp before performing the fuel cut control in lockup ON time is a timing advanced than the idling time valve closing period, in case when the variable valve timing mechanism 14 is used to control the valve closing period of the intake valve 12 before the time when the piston 9 attained the intake bottom dead center.

In the former case, the amount of the air substantially inhaled into the cylinder 8 decreases as a part of air inhaled once into the cylinder 8 is pushed back from the intake port 10 by the elevation of the piston 9. In the latter case, the amount of the air inhaled into the cylinder 8 is limited and reduced as the intake valve 12 is closed at an early timing before the piston 9 attains the intake bottom dead center.

Thus set provisory target valve timing Tvtt is set as target valve timing Tvt (step S16), and the variable valve timing mechanism 14 is controlled so that the actual valve closing timing of the intake valve 12 agrees with its target valve timing Tvt. As the result, the substantial intake air amount immediately before performing the fuel cut control reduces, lowering the output torque of the internal combustion engine 1.

In the state immediately before performing the fuel cut control, the process from the aforementioned steps S11 to S16 is executed every predetermined time Δt, and a state wherein the amount of the air inhaled into the cylinder 8 decreases or state wherein the output torque of the internal combustion engine 1 lowers is sustained. When a predetermined time has elapsed from establishment of fuel cut control execution determination, the aforementioned flag before performing the fuel cut control is turned OFF, and the determination in the step S13 becomes negative. In this case, it advances to the step S16 skipping the steps S14 and S15, and since the idle time valve timing Tvi is set as provisory target valve timing Tvtt, it is set as target valve timing Tvt, and the actual valve timing is controlled to be this target timing Tvt. Therefore, in the internal combustion engine 1, as air is inhaled and exhausted with fuel supply suspended, a torque accompanying a so-called pumping loss is generated as braking torque (engine brake torque).

In case where the valve closing timing of the intake valve 12 is controlled as mentioned above also, the air amount in the cylinder 8 becomes lower than the idling time and the fuel cut control is performed with the output torque of the internal combustion engine 1 lowered, and as the result, decrease of the output torque of the internal combustion engine 1 according to the fuel cut control execution occurs with a torque lower than the idling time, eventually, reducing the variation range of the torque directed to the driving wheel 7 from the internal combustion engine 1 in the power transmission system, thereby restraining or preventing shock or vibration.

If the determination is negative in the step S14 by the fact that the lockup clutch 3 is released, it advances immediately to the step S16 without modification control of the valve closing timing of the intake valve 12. This is similar to the case where the determination is negative in the step S4 in the control embodiment shown in Fig. 1. If the determination is negative in the step S11 by the fact of being out of idling state, it is set to the normal valve timing. In short, a valve timing map value is read out according to the output target torque, engine revolution and the like, and set as provisory target valve timing Tvtt (step S17). Thereafter, it advances to the step S16.

In the aforementioned respective control embodiments, the torque variation range is reduced by lowering the output torque of the internal combustion engine 1 immediately before performing the fuel cut control. However, in place of this control, or in addition to this control, the torque variation range according to the fuel cut control execution may be reduced by temporally and relatively increasing the output torque of the internal combustion engine 1 (reducing the negative torque) immediately after performing the fuel cut control. Now, an embodiment of such control immediately after performing the fuel cut control will be described.

Fig. 4 is a flow chart showing an embodiment of control thereof, and the control embodiment illustrated here applied to the internal combustion engine 1 composed to control the idle speed by the electronic throttle valve 16. In addition, the routine shown by the flow chart in Fig. 4 is executed every predetermined time (several tens of microseconds) At. In the control embodiment shown in Fig. 4, first, it is determined whether the idle switch is ON or not (step S21). This is a process for determining if it is the idling state or not and is a process similar to the step S1 shown in Fig. 1 or the step S11 shown in Fig. 3.

If the determination of the step S21 is affirmative according to the fact being in the idle state, or the idle switch is turned ON, an opening which corresponds to the intake air amount required for maintaining the idle speed or idle speed control opening isc is set as provisory target opening tt of the electronic throttle valve 16 (step S22). Here, this idle speed control opening isc is a predetermined value, or an established value updated by learning control.

Next, it is determined whether the flag showing the fuel cut control execution with the lockup clutch 3 (flag of fuel cut in execution when lockup ON) is ON or not (step S23). As mentioned above, the fuel cut control to suspend fuel supply to the internal combustion engine 1 is performed when the lockup clutch 3 is engaged and the internal combustion engine 1 revolution is maintained equal or superior to a predetermined revolution, during the deceleration with the idling completed. This state can be determined based on the control state by the aforementioned engine-electronic control unit 21 and the transmission-electronic control unit 22, and the flag is set to ON or OFF based on the determination result thereof.

When the flag is turned ON by the fuel cut control execution with the lockup clutch 3 ON, or the flag is ON by the fuel cut control execution, in short, when the determination of step S23 is affirmative, it is determined whether a count time Cfc by a counter for countering the time that has elapsed after the start of the fuel cut control (fuel cut continuance counter) is shorter or not than a predetermined time (step S24). If the determined of this step S24 is affirmative, the time that has elapsed after the start of the fuel cut control is short, the state is that of immediately after performing the fuel cut control and, in this case, an opening fca after fuel cut execution when lockup ON is set as provisory target opening tt of the electronic throttle valve 16 (step S25). Here, this opening fca after fuel cut execution when lockup ON is an opening larger than the aforementioned idle speed control opening isc (fca > isc) and, therefore, is an opening increasing the intake air amount than the idling time. Thus set provisory target opening tt is set as target throttle opening t (step S26), and the opening of the electronic throttle valve 16 is controlled to be this target opening t.

Consequently, immediately after the start of fuel cut control, the throttle opening is set to an opening larger than the opening for maintaining the idle speed, provided that the lockup clutch 3 is engaged. As the result, the resistance to the air flow taken into the internal combustion engine 1 reduces in a state without fuel supply state, preventing the inside of the cylinder 8 becoming a large negative pressure. In short, the increase of negative torque (braking torque) due to the pumping loss of the internal combustion engine 1 is restrained, and the output torque of the internal combustion engine 1 increases relatively. In other words, the output torque of the internal combustion engine 1 decrease amount due to the execution of fuel cut control is reduced, and the variation range of the torque directed to the driving wheel 7 from the internal combustion engine 1 in the power transmission system is reduced, thereby restraining or preventing shock or vibration.

In the state immediately after performing the fuel cut control, the process from the aforementioned steps S21 to S26 is performed every predetermined time Δt and a state where the intake air amount is increased, or a state where the output torque of the internal combustion engine 1 is relatively increased is sustained. Then, when a predetermined time α has elapsed after the start of fuel cut control execution, the time Cfc measured by the aforementioned counter attaints the predetermined time α, and the determination of the step S24 becomes negative. In this case, it advances to the step S26 skipping the step S25, and idle speed control opening isc set previously in the step S22 as provisory target opening tt is set as target throttle opening t. In short, the throttle opening, that has been relatively increased for the predetermined time, after the start of fuel cut control is reduced to an opening for maintaining the idle speed. Consequently, as the air intake by the internal combustion engine 1 is restrained, the pumping loss increases, and the so-called engine brake is set to an expected magnitude.

Fig. 5 shows the change of the output torque TE of the internal combustion engine 1 in case of executing, as shown above, the increase control of the intake air amount immediately after performing the fuel cut control. In short, if the accelerator opening Acc becomes zero at the time point t10, the determination of fuel cut execution is established, provided that idling of the internal combustion engine 1 is completed, and the revolution NE of the internal combustion engine 1 is equal or superior to the predetermined revolution. Fuel cut control is executed at the time point 11 where a predetermined time has elapsed from this time point, and flag of fuel cut in execution when lockup ON is turned ON, and the counter Cfc starts counting the time. Further, the aforementioned opening fca after performing fuel cut control when lockup ON is set as target throttle opening t. In this case, the output torque TE of the internal combustion engine 1 lowers according to the execution of fuel cut control. However, as the throttle opening is set to an opening larger than the opening for maintaining the idle speed, the output torque TE becomes relatively high, or the negative torque increase is restrained as shown by the solid line in Fig. 5. In opposition, if it is set to the opening for maintaining the idle speed, the time torque becomes as shown by the broken line in Fig. 5, eventually, reducing the variation range of the torque according to the execution of fuel cut control, and restraining or preventing shock and vibration.

Therefore, the throttle opening is maintained at the opening fca after performing fuel cut control when lockup ON for the predetermined time α, and at the time point t12 where the predetermined time α has elapsed, the throttle opening is controlled taking the idle speed control opening isc as the target opening, and the restriction of throttle opening increases the negative torque of the internal combustion engine 1, or the output torque TE lowers. Accordingly, an expected engine brake is generated.

The determination in the step S23 becomes negative, in case where the fuel cut control is not executed even in the idling state by the fact that fuel cut control execution conditions are not met. In this case, it advances immediately to the step S26 and the control for relatively increasing the output torque of the internal combustion engine 1 or the control for temporally increasing the throttle opening is not executed. This is to prevent the output torque from increasing by the increase of intake air amount, as the fuel supply is sustained.

Further, if the determination is negative in the step S1 by the fact of being out of idling state, a normal throttle opening control is executed (step S27). In short, the throttle opening is determined based on the output target torque or the internal combustion engine revolution (engine revolution), and set as provisory target throttle opening tt. Thereafter, it advances to the step S26.

In the aforementioned control embodiment shown in Fig. 4, the embodiment is applied to an internal combustion engine 1 composed to control the idle speed by the electronic throttle valve 16. However, in the internal combustion engine 1 composed to control the idle speed by the aforementioned ISC valve 18, the increase control of the intake air amount immediately after performing the fuel cut control is performed by temporally increasing the opening of this ISC valve 18. Such control can be represented, for example, by a control routine wherein the throttle opening in the control embodiment shown in Fig. 4 is substituted with the ISC valve opening.

As mentioned before, the intake air amount into the cylinder 8 can also be controlled by changing the valve closing timing of the intake valve 12, other than the control by the electronic throttle valve 16 or ISC valve 18 disposed at the upstream side of the intake port 10. Therefore, the control to relatively increase the output torque TE of the internal combustion engine 1 for the predetermined time α immediately after performing the fuel cut control can be controlled by changing the valve closing timing of the intake valve 12. This control is similar to the control shown in Fig. 3 mentioned above, and this will be described referring to Fig. 6.

The routine shown in Fig. 6 is executed every predetermined time Δt, and, first, it is determined whether the idle switch is ON or not (step S31). This is a process similar to the step S1 shown in Fig. 1 or the step S11 shown in Fig. 3. If the determination of the step S31 is affirmative according to the fact being in the idle state, the valve timing of idle time Tvi is set as provisory target valve timing Tvtt (step S32). This is a control similar to the step S12 shown in Fig. 3 mentioned above.

Next, it is determined whether the flag showing the fuel cut control execution with the lockup clutch 3 (flag of fuel cut in execution when lockup ON) is ON or not (step S33). This is a control similar to the step S23 shown in Fig. 4 mentioned above.

When the flag is turned ON by the fuel cut control execution with the lockup clutch 3 turned ON, or the flag is ON by the fuel cut control execution, in short, when the determination of step S33 is affirmative, it is determined whether the count time Cfc by a counter for countering the time that has elapsed after the start of the fuel cut control (fuel cut continuance counter) is shorter or not than a predetermined time (step S34). This is a control similar to the step S24 shown in Fig. 4 mentioned above.

If the determination of this step S34 is affirmative, the time that has elapsed after the start of the fuel cut control is short, the state is that of immediately after performing the fuel cut control and, in this case, a valve timing Tvfca after fuel cut execution when lockup ON is set as provisory target valve timing Tvtt (step S35). Here, this valve timing Tvfca after fuel cut execution when lockup ON is a valve timing delayed than the idling time valve closing timing, in case when a variable valve timing mechanism 14 is used that controls the valve closing timing of the intake valve 12 after the time when the piston 9 has attained the intake bottom dead center is used. On the other hand, the valve timing Tvfca after fuel cut execution when lockup ON is a valve timing earlier than the idling time valve closing timing, in case when a variable valve timing mechanism 14 is used that controls the valve closing timing of the intake valve 12 before the piston 9 attains the intake bottom dead center is used.

The thus set provisory target valve timing Tvtt is set as target valve timing Tvt (step S36), and the variable valve timing mechanism 14 is controlled so that the actual valve closing timing of the intake valve 12 agrees with its target valve timing Tvt. As the result, in the former case wherein the valve closing timing of the intake valve 12 is delayed, a part of air inhaled once into the cylinder 8 is pushed back from the intake port 10 by the elevation of the piston 9, while in the latter case wherein the valve closing timing of the intake valve 12 is advanced, the amount of the air inhaled into the cylinder 8 and compressed by the reciprocation of the piston 9 is reduced as the air amount itself inhaled into the cylinder 8 is restrained. As the result, the negative torque due to pumping loss is reduced. In short, the output torque of the internal combustion engine 1 increases relatively, reducing the variation range of the torque according to the execution of fuel cut control, and restraining or preventing shock and vibration, similarly as the control embodiment shown in Fig. 4, thereby restraining or preventing shock or vibration.

If the determination in the step S33 becomes negative by the fact that flag of fuel cut in execution when lockup ON is OFF, and if the determination in the step S34 becomes negative by the fact that a time longer than the predetermined time α has elapsed, it advances to the step S36 skipping the step S35, and the idling time valve closing timing Tvi as target valve timing Tvt, as in the control embodiment shown in Fig. 3. If the determination is negative in the step S31 by the fact of being out of idling state, a valve timing map value is read out according to the output target torque, engine revolution and the like, and set as provisory target valve timing Tvtt (step S37). Thereafter, it advances to the step S36, as in the control embodiment shown in Fig. 3.

By the way, since vehicle vibration or shock is provoked by a sudden change of the driving torque of the driving wheel 7, it will be enough to reduce the driving torque change amount per unit time, in order to prevent or control vibration and shock. In each of the aforementioned embodiments, it is composed to control the magnitude of the torque directed to the driving wheel 7 in the power transmission system by controlling the substantial intake air amount of the internal combustion engine 1 which is the power source. In opposition, the torque directed to the driving wheel 7 in the power transmission system can also be controlled by changing the magnitude of the torque received by a member absorbing torque in the power system other than the internal combustion engine 1. Now, an embodiment thereof will be described.

Fig. 7 shows an embodiment of a control wherein a compressor 23 for variable capacity type air conditioner, which is auxiliary equipment, is used as an example of operation member. First, it is determined whether the flag before performing the fuel cut control is ON or not (step S41). This is a determination process similar to the step S3 shown in Fig. 1 or the step S13 shown in Fig. 3. If the fuel cut control determination is established and, at the same time, if the determination of the step S41 is affirmative by the fact that the state is before execution of this control, increase before fuel cut control execution Pacp is set as air conditioner discharge increase and decrease amount Pac (step S42). This can be performed, for instance, by an electronic control unit for air conditioner.

On the other hand, a basic air conditioner discharge amount Pb is set by the normal process (step S43). To be more specific, a basic air conditioner discharge amount Pb is calculated as the sum of the value of deviation between a room temperature tr and a set temperature tt multiplied by a predetermined coefficient K, a value F(to) determined based on an open air temperature to and a value G(h) determined based on a sunlight intensity h. The air conditioner discharge increase Pac is added to this basic air conditioner discharge amount Pb to determine a final air conditioner discharge amount P (step S44).

Therefore, immediately before performing the fuel cut control, the driving torque of the compressor 23 for air conditioner, or torque to be input to the compressor 23 for air conditioner from the internal combustion engine 1 increases, and accordingly, the torque directed to the driving wheel 7 from the internal combustion engine 1 through the transmission 2 lowers. As the result, the torque in the power transmission system from the internal combustion engine 1 to the driving wheel 7 is already decreased, even when the output torque TE of the internal combustion engine 1 decreases according to the fuel cut control execution, reducing the driving wheel torque variation range, consequently, restraining or preventing shock and vibration.

In opposition, if the determination of the step S41 is negative by the fact that the flag before performing the fuel cut control is OFF, it is determined whether the flag of fuel cut control in execution when lockup ON is ON or not (step S45). In short, it is determined whether the fuel cut control is already executed or not, or whether the fuel cut control has started of not. This is a determination similar to the step S23 shown in Fig. 4 mentioned above.

If the fuel cut control has already started, the determination of this step S45 is affirmative, as this flag is turned ON. In this case, it is determined whether the count time Cfc of the fuel cut continuance counter is shorter or not than the predetermined time α (step S46). Namely, it is determined whether it is immediately after the start of fuel cut control or not. This is a determination step similar to the step S24 shown in Fig. 4. If the determination of this step S46 is affirmative, it is the state immediately after the start of fuel cut control and decrease after fuel cut control execution Paca is set as air conditioner discharge increase and decrease amount Pac (step S47). This can be performed, for instance, by an electronic control unit for air conditioner.

Thereafter, it proceeds to the aforementioned step S43 and the step S44 consecutively, the basic air conditioner discharge amount Pb is determined, and this basic air conditioner discharge amount Pb is added to the decrease after fuel cut control execution Paca. In short, the decrease after fuel cut control execution Paca is subtracted from the basic air conditioner discharge amount Pb, to obtain the final air conditioner discharge amount P.

Therefore, immediately after performing the fuel cut control, the driving torque of the compressor 23 for air conditioner, or torque input to the compressor 23 for air conditioner from the internal combustion engine 1 lowers, and accordingly, the torque directed to the driving wheel 7 from the internal combustion engine 1 through the transmission 2 increases. As the result, the torque in the power transmission system from the internal combustion engine 1 to the driving wheel 7 is restrained from decreasing, even when the output torque TE of the internal combustion engine 1 decreases according to the fuel cut control execution, reducing the driving wheel torque variation range, thereby restraining or preventing shock and vibration.

If the determination of the step S45 is negative, the determination for performing the fuel cut control is not established, and this control is not executed and there is no factor to increase or decrease the power system torque and, consequently, in this case, the air conditioner discharge increase and decrease amount Pac is set to "0" (step S48), then proceeding to the step S43. Also, similarly, if a time longer than the predetermined time α has elapsed after starting the fuel cut control, or if the determination in the step S46 is affirmative, as it is necessary to perform a normal fuel cut control and to generate an intended engine brake torque, it advances to the step S48, and the air conditioner discharge increase and decrease amount Pac is set to "0". Especially, the aforementioned control unit according to the invention is effective for performing fuel cut control by engaging the lockup clutch 3 up to a low speed, in a vehicle loading a continuous transmission.

Now the relation between the invention and the aforementioned respective embodiments will be described. The functional means of steps S5, S6 shown in Fig. 1, the functional means of steps S15, S16 shown in Fig. 3 and the functional means of steps S42, S44 shown in Fig. 7 correspond to means for controlling immediately before the fuel cut control of the invention, while the functional means of steps S35, S36 shown in Fig. 6 and the functional means of steps S47, S44 shown in Fig. 7 correspond to means for controlling immediately after the fuel cut control of the invention.

In the aforementioned embodiment, it is composed to decrease the torque in the power system, by changing the intake air amount to the internal combustion engine 1 in the idling time, or by increasing the load to the internal combustion engine 1 by the compressor 23 for air conditioner. However, in place of or in addition to this, the torque in the driving system immediately before the fuel cut control may also be decreased by increasing the torque absorbed by the motor generator in a hybrid vehicle, or by generating a braking power by the antilock braking system. Also, the control for temporally increasing the torque in the driving system immediately after the fuel cut control may be performed by applying torque by the motor or motor generator in a hybrid vehicle. Further, the auxiliary equipment in the invention is not limited to the variable capacity type compressor for air conditioner mentioned above, but it may be alternator, oil pump for power steering or other equipment. Though respective controls shown in Fig. 1 to Fig. 7 have been described individually, in the aforementioned embodiments, these controls may be performed in parallel provided that they do not interfere with each other.

Claims

A control apparatus of an internal combustion engine for performing fuel cut control for suspending fuel supply to the internal combustion engine during the operation, characterized in that it comprises at least any one of:

means for controlling immediately before the fuel cut control to control the torque from the internal combustion engine (1) to driving wheels (7) in a power transmission system from the internal combustion engine (1) to the driving wheels (7) in a decrease direction, immediately before performing the fuel cut control, in case when the fuel cut control execution is determined; and

means for controlling immediately after the fuel cut control to control the torque from the internal combustion engine (1) to the driving wheels (7) in the power transmission system from the internal combustion engine (1) to the driving wheels (7) in an increase direction, immediately after performing the fuel cut control in case when the fuel cut control is executed.
The control apparatus of an internal combustion engine according to claim 1, characterized in that

the means (12, 16, 18) for controlling immediately before the fuel cut control is means for reducing air intake amount to the internal combustion engine (1), and

the means (12, 16, 18) for controlling immediately after the fuel cut control is means for increasing air intake amount to the internal combustion engine (1).
The control apparatus of an internal combustion engine according to claim 1 or 2, characterized in that

the internal combustion engine (1) comprises an electrically controllable throttle valve (16),

the means for controlling immediately before the fuel cut is means for reducing the opening of the throttle valve (16), and

the means for controlling immediately after the fuel cut control is means for increasing the opening of the throttle valve (16).
The control apparatus of an internal combustion engine according to claim 1 or 2, characterized in that

the internal combustion engine (1) comprises a throttle valve (16) whose opening is changed by the acceleration or deceleration operation and another valve (18) for controlling the amount of the air inhaled bypassing the throttle valve (16),

the means for controlling immediately before the fuel cut control is means for reducing the opening of the another valve (18), and

the means for controlling immediately after the fuel cut control is means for increasing the opening of the another valve (18).
The control apparatus of an internal combustion engine according to claim 1, characterized in that

the internal combustion engine (1) is a reciprocating type internal combustion engine (1) having a piston (9) reciprocating in the cylinder (8) and an intake valve (12) for opening/closing the intake port (10) of the cylinder (8) according to the piston motion, and

the means for controlling immediately before the fuel cut control and the means for controlling immediately after the fuel cut control may are means for changing the intake valve closing timing to a direction decreasing the air intake amount in the cylinder (8).
The control apparatus of an internal combustion engine according to claim 1, further comprising an operation member (23, 24) for receiving torque from the power transmission system, characterized in that

the means for controlling immediately before the fuel cut control is means for reducing the torque of the power transmission system by increasing the torque to be input into the operation member (23, 24), and

the means for controlling immediately after the fuel cut control is means for decreasing the torque to be input into the operation member (23, 24) relatively increasing the torque of the power transmission system.
The control apparatus of an internal combustion engine according to claim 6, characterized in that

the operation member (23, 24) is auxiliary equipment coupled to the internal combustion engine,

the means for controlling immediately before the fuel cut control is means for increasing the driving torque of the auxiliary equipment, and

the means for controlling immediately after the fuel cut control is means for decreasing the driving torque of the auxiliary equipment.
The control apparatus of an internal combustion engine according to any one of claims 1 to 7, characterized in that

the power transmission system includes a torque transmission variable mechanism (2) for changing the torque transmission efficiency between the internal combustion engine (1) and the driving wheels (7), and

the apparatus further includes a torque transmission variable control means for setting this torque transmission variable mechanism (2) in a state where the torque transmission efficiency becomes relatively high before and after performing the fuel cut control.
A control method of an internal combustion engine for performing fuel cut control for suspending fuel supply to the internal combustion engine during the operation, characterized in that it comprises at least any one of steps:

controlling the torque from the internal combustion engine (1) to driving wheels (7) in a power transmission system from the internal combustion engine (1) to the driving wheels (7) in a decrease direction, immediately before performing the fuel cut control, in case when the fuel cut control execution is determined; and

controlling the torque from the internal combustion engine (1) to the driving wheels (7) in the power transmission system from the internal combustion engine (1) to the driving wheels (7) in an increase direction, immediately after performing the fuel cut control in case when the fuel cut control is executed.