JP4605137B2 - Fuel cut control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel cut for a spark ignition type internal combustion engine.

  In a spark ignition type internal combustion engine mounted on a vehicle such as a passenger car, a truck, or a bus, from the viewpoint of suppressing fuel consumption, for example, when the vehicle is decelerated, a fuel cut is performed to stop fuel supply to the internal combustion engine. . When the fuel supply to the internal combustion engine is resumed from the fuel cut state, the internal combustion engine suddenly generates torque. For this reason, a shock may be given to the vehicle and the vehicle occupant. In order to reduce this shock, when the fuel supply to the internal combustion engine is restarted from the fuel cut state, control is performed so that the ignition timing of the internal combustion engine is retarded from normal (for example, Patent Document 1). ).

JP 2004-353478 A paragraph number 0060

  However, Patent Document 1 does not disclose conditions for executing fuel cut or conditions for executing retard of ignition timing when fuel supply is resumed from the fuel cut state. For this reason, the range in which the fuel cut can be executed and the range in which the retard of the ignition timing can be executed when the fuel supply is resumed from the fuel cut state is expanded to suppress the fuel consumption of the internal combustion engine, and the fuel cut state. There is room for improvement in suppressing the shock when restarting the fuel supply from the start, or more effectively avoiding the stop of the internal combustion engine during the fuel cut.

  Therefore, the present invention has been made in view of the above, and is an internal combustion engine that can expand the range in which the fuel cut can be performed and the range in which the retard of the ignition timing can be performed when the fuel supply is resumed from the fuel cut state. An object of the present invention is to provide a fuel cut control device.

  In order to solve the above-described problems and achieve the object, a fuel cut control device for an internal combustion engine according to the present invention controls execution of fuel cut for the internal combustion engine and resumption of fuel supply, and per unit time. A fuel cut condition determining unit that determines whether or not to perform a fuel cut by comparing a change in the rotational speed of the internal combustion engine with a first control determination threshold value that is changed according to the engine rotational speed; When the change in the rotational speed of the internal combustion engine per unit time is compared with the second control determination threshold value that is changed according to the engine rotational speed, and the fuel supply is resumed from the fuel cut state If it is determined that the ignition timing retarding control is to be executed, and a fuel cut return control condition determining unit that determines whether or not to execute the control to retard the ignition timing at the same time, the ignition timing of the internal combustion engine Set retard amount And, when returning from the fuel cut is characterized in that it comprises a fuel cut return time control unit to ignite on the basis of the retard amount set.

  The fuel cut control device for an internal combustion engine includes a first control determination threshold value that is changed according to a change in the rotation speed of the internal combustion engine per unit time, that is, a change rate of the rotation speed of the internal combustion engine, and the engine rotation speed. To determine whether or not to execute the fuel cut. Further, the engine speed change rate is compared with a second control determination threshold value that is changed according to the engine speed, and the ignition timing is retarded when the fuel supply is resumed from the fuel cut state. It is determined whether or not. As a result, the range in which the fuel cut can be executed and the range in which the ignition timing can be retarded when the fuel supply is resumed from the fuel cut state can be expanded.

  In the fuel cut control device for an internal combustion engine as in the fuel cut control device for an internal combustion engine according to the present invention, the first control determination threshold value and the second control determination threshold value are the engine speed. It is preferable to make it smaller with the decrease of the.

  As in the fuel cut control device for an internal combustion engine according to the next aspect of the present invention, in the fuel cut control device for the internal combustion engine, the fuel cut return control unit is configured to perform the retardation based on the pressure in the intake pipe of the internal combustion engine. It is preferable to set the amount.

  As in the fuel cut control device for an internal combustion engine according to the present invention, in the fuel cut control device for the internal combustion engine, the retard amount may be increased as the pressure in the intake pipe of the internal combustion engine decreases. preferable.

  The fuel cut control device for an internal combustion engine according to the present invention can expand the range in which the fuel cut can be executed and the range in which the ignition timing can be retarded when the fuel supply is resumed from the fuel cut state.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited by the best mode for carrying out the invention (hereinafter referred to as an embodiment). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, or those that are substantially the same, so-called equivalent ranges.

  This embodiment is control related to fuel cut for an internal combustion engine, and is characterized by the following points. That is, it is determined whether or not the fuel cut is to be executed by comparing the rate of change of the engine speed with the first control determination threshold value that is changed according to the engine speed. Further, it is determined whether or not to execute the retard of the ignition timing when returning from the fuel cut by comparing the rate of change of the engine speed with a second control determination threshold value that is changed according to the engine speed. judge.

  FIG. 1 is a cross-sectional view showing an internal combustion engine according to this embodiment. FIG. 2 is a schematic diagram showing a state in which the internal combustion engine according to the present embodiment is mounted on a vehicle. FIG. 1 shows a single cylinder provided in an internal combustion engine. The internal combustion engine shown in FIG. 2 is a four-cylinder internal combustion engine. However, the internal combustion engine to which the present invention can be applied is not limited to a multi-cylinder or a single cylinder. And the arrangement | positioning is not ask | required.

  The internal combustion engine 1 according to the present embodiment ignites an air-fuel mixture in the combustion chamber 2B by an ignition plug 7 as ignition means, and reciprocates the piston 5 in the cylinder 2 by the combustion pressure, so-called reciprocating spark. It is an ignition type internal combustion engine. The internal combustion engine 1 is a so-called direct injection internal combustion engine provided with a direct injection valve 3 that directly injects fuel F into a cylinder 2 (hereinafter referred to as “inside cylinder”) 2I as fuel supply means. In the present embodiment, the internal combustion engine 1 is not limited to a so-called direct injection internal combustion engine, but may be a so-called port injection internal combustion engine that injects fuel F into an intake port that is a part of the intake pipe 22. In the present embodiment, the internal combustion engine 1 may be an internal combustion engine that uses both direct injection and port injection. The internal combustion engine 1 may include a supercharging means and a variable compression mechanism.

  In the internal combustion engine 1, the intake air amount is adjusted by an electronic throttle valve 70 provided in the intake passage 21. The electronic throttle valve 70 includes a butterfly valve 71, an actuator 72 that drives the butterfly valve 71, and a throttle position sensor 73 that detects the opening degree of the butterfly valve 71. The ECU (Electronic Control Unit) 30 acquires the output from the accelerator opening sensor 44, sends a control signal to the actuator 72, and based on the feedback signal of the butterfly valve opening from the throttle position sensor 73, the butterfly valve 71 To an appropriate opening.

  A crank angle CA of the crankshaft 6 is detected by a crank angle sensor 41 attached to the internal combustion engine 1. The ECU 30 acquires outputs from the crank angle sensor 41, the intake pipe pressure sensor 42, the air flow sensor 43, the accelerator opening sensor 44, the water temperature sensor 45, and other sensors to obtain the ignition timing of the internal combustion engine 1 and the internal combustion engine 1. Determine the fuel injection amount. Then, based on the determined value, the fuel F is injected from the direct injection valve 3, and the spark plug 7 attached to the cylinder head 1h of the internal combustion engine 1 is energized and discharged to ignite the air-fuel mixture in the combustion chamber 2B.

  The air A from which dust and dirt have been removed by the air cleaner 81 is measured by the air flow sensor 43, passes through the intake passage 21, passes through the electronic throttle valve 70, and is guided to the surge tank 20. The air A in the surge tank 20 is introduced into the cylinder 2I from the intake pipe 22 serving as an intake passage through the intake port 9i provided in the cylinder head 1h of the internal combustion engine 1 and the intake valve 8i. Then, an air-fuel mixture is formed with the fuel spray Fm injected from the direct injection valve 3. This air-fuel mixture is ignited by the discharge of the spark plug 7 and burned by flame propagation. In the present embodiment, the ignition timing is determined based on the signal from the crank angle sensor 41, but may be determined based on the rotation angle of the exhaust camshaft Sc that operates the exhaust valve 8e.

  The combustion pressure of the air-fuel mixture is transmitted to the piston 5 and causes the piston 5 to reciprocate. The reciprocating motion of the piston 5 is transmitted to the crankshaft 6 via the connecting rod 4, where it is converted into rotational motion and taken out as the output of the internal combustion engine 1. The air-fuel mixture after combustion becomes exhaust gas Ex and passes through between the exhaust port 9e and the exhaust valve 8e and is discharged to the exhaust passage 23. The exhaust gas Ex is guided to a purification catalyst (for example, a three-way catalyst) 83 attached to the exhaust passage 23, where it is purified and discharged into the atmosphere.

  The output of the internal combustion engine 1 is guided to an automatic transmission (AT) 55 to drive the left front wheel FL and the right front wheel FR, which are drive wheels of the vehicle 100, to cause the vehicle 100 to travel. The vehicle 100 is a so-called front wheel drive (FF) vehicle having four cylinders 2 and having a so-called four-cylinder internal combustion engine 1 as a power generation source, and includes a left rear wheel RL and a right rear wheel. The wheel RR is a driven wheel that does not generate a driving force. In the present embodiment, the vehicle driving method is not limited. The traveling speed (vehicle speed) of the vehicle 100 is calculated based on a signal acquired by the ECU 30 from the vehicle speed sensor 46 and used for controlling the internal combustion engine 1. Further, the ECU 30 acquires shift information (for example, the current shift speed and shift oil temperature) of the automatic transmission 55 and uses it for control related to fuel cut of the internal combustion engine according to the present embodiment.

  FIGS. 3A and 3B are diagrams for explaining control related to fuel cut of the internal combustion engine according to the present embodiment. When the internal combustion engine 1 is mounted on the vehicle 100 as a power generation source, the fuel F supplied to the internal combustion engine 1 is cut according to the operating conditions of the vehicle 100, the internal combustion engine 1, the automatic transmission 55, and the like. The supply of fuel to the internal combustion engine 1 is stopped, and the fuel consumption of the internal combustion engine 1 is suppressed. When the rotational speed NE (hereinafter referred to as engine rotational speed) NE of the internal combustion engine 1 becomes equal to or lower than a predetermined rotational speed enrt (see FIG. 3-2), fuel supply to the internal combustion engine 1 is resumed (return from fuel cut). Here, the engine speed enrt that returns from the fuel cut is referred to as a return speed enrt.

  When the supply of fuel to the internal combustion engine 1 is resumed, if the intake air amount of the internal combustion engine 1 is large, the engine speed NE increases rapidly, which may cause a shock to the vehicle 100 and its passengers. . Therefore, at the time of return from the fuel cut, the ignition timing of the internal combustion engine 1 is set to be retarded from the ignition timing determined according to the operating conditions of the internal combustion engine 1 at that time, so that the engine speed NE is rapidly increased. Suppresses the rise. This is called fuel cut return retardation control.

  When the fuel cut is executed, for example, when the decrease in the engine speed NE is large due to a large deceleration of the vehicle 100 or the like, if the ignition timing is retarded at the time of return from the fuel cut, the internal combustion is more than necessary. There is a possibility that the torque of the engine 1 is reduced and a necessary driving force cannot be obtained, or an engine brake is applied. Further, when the engine speed NE is greatly reduced during the fuel cut, the operation of the internal combustion engine 1 may be stopped. For this reason, when the decrease in the engine speed NE during the fuel cut is large, the control that prohibits the retard of the ignition timing when returning from the fuel cut or the control that does not execute the fuel cut itself is selected and executed. The

A parameter used when selecting a control for prohibiting the retard of the ignition timing upon return from the fuel cut and a control for not executing the fuel cut itself is based on the degree of decrease in the engine speed NE. FIG. 3A shows a change in the engine speed NE when a fuel cut (F / C) is performed. As shown in Figure 3-1, when the fuel cut time t ₁ is executed (F / C_ON), the engine speed NE is decreased with time. In the example shown in Figure 3-1, the fuel cut is stopped (F / C_OFF) at time t _2. In the example shown in FIG. 3A, the engine speed NE decreases by NE_d at time Δt.

  In the present embodiment, the engine speed change rate ΔNE is used as a parameter used when selecting control for prohibiting the retard of the ignition timing upon return from the fuel cut and control for not executing the fuel cut itself. This is the absolute value of the change (more specifically, the degree of decrease) in the engine speed NE per unit time, and ΔNE = | −NE_d / Δt |. When the engine speed change rate ΔNE increases, the degree of decrease in the engine speed NE per unit time increases, and when the engine speed change rate ΔNE decreases, the degree of decrease in the engine speed NE per unit time decreases. It means to become.

  The dotted line α and dotted line β in FIG. 3-2 are threshold values (hereinafter referred to as control determination threshold values) for determining whether or not to execute fuel cut and whether or not to prohibit fuel cut return retard control. Yes, the control determination threshold values α and β are constant regardless of the engine speed NE. Note that α> β. Conventionally, when the engine speed change rate ΔNE is equal to or greater than the control determination threshold value α, the fuel cut itself is not executed (that is, the fuel cut return delay angle control itself is not executed). When the engine speed change rate ΔNE is smaller than the control determination threshold value α, the fuel cut is executed. When the engine speed change rate ΔNE is smaller than the control selection threshold value α and equal to or greater than the control determination threshold value β, the fuel cut is executed, but the fuel cut return delay angle control is prohibited. When the engine speed change rate ΔNE is smaller than the control determination threshold value β, the fuel cut is executed, and when returning from the fuel cut, the fuel cut return retarding control is executed.

  In the present embodiment, the first control determination threshold value F (α) used when determining whether or not to execute fuel cut is used when determining whether or not fuel cut return retard control is prohibited. The second control determination threshold value F (β) is a function of the engine speed NE, and these are changed according to the engine speed NE. In the present embodiment, as shown in FIG. 3-2, the first control determination threshold value F (α) and the second control determination threshold value F (β) are decreased in accordance with the decrease in the engine speed NE. .

  When the engine speed NE is large, even if the engine speed change rate ΔNE is large, there is a low possibility that the internal combustion engine 1 will stop during the fuel cut. Therefore, when the engine speed is large, the first control determination threshold value F (α) is increased. On the other hand, as the engine speed NE decreases, the risk that the internal combustion engine 1 will stop during fuel cut increases. Therefore, as the engine speed NE decreases, the first control determination threshold value F (α) is decreased.

  When the engine speed NE is large, the intake air amount of the internal combustion engine 1 also increases, so it is preferable to widen the range in which the fuel cut return retardation control is executed. In addition, when the engine speed NE is large, the possibility that the internal combustion engine 1 stops during fuel cut is low. For this reason, the second control determination threshold value F (β) is increased as the engine speed NE increases. That is, as the engine speed NE decreases, the second control determination threshold value F (β) is decreased.

  As a result, fuel cut and fuel cut delay control can be executed more appropriately. Therefore, the range in which fuel cut can be executed while avoiding the stop of the internal combustion engine 1 during fuel cut execution, and the fuel cut return delay angle The range in which control can be performed can be expanded. As a result, the fuel consumption of the internal combustion engine 1 can be suppressed, and the range in which the shock at the time of return from the fuel cut can be suppressed is expanded. Moreover, the stop of the internal combustion engine during fuel cut can be avoided more effectively. Here, the function forms of the first control determination threshold value F (α) and the second control determination threshold value F (β) are not limited to those shown in FIG. For example, it may change linearly or may change with an inflection point within the range of the engine speed NE in the operating range of the internal combustion engine 1. Further, at the same engine speed NE, the first control determination threshold value F (α)> the second control determination threshold value F (β).

  For example, as shown in FIG. 3-2, in the range where the engine speed NE is equal to or higher than the return speed enrt, the engine speed change rate ΔNE is larger than when the constant control determination threshold value α is used. Since the fuel cut can be executed up to the range (the range indicated by B in FIG. 3-2), the fuel consumption of the internal combustion engine can be further suppressed. Further, in a range where the engine speed NE is smaller than the return speed enrt, a larger range of the engine speed change rate ΔNE (in FIG. 3-2) than in the case where the control determination threshold value β which is a constant is used. Since the fuel cut return retardation control can be executed up to the range indicated by C), the range in which the shock at the time of return from the fuel cut can be suppressed is expanded. Further, in the range where the engine speed NE is smaller than the return speed enrt, the range of the engine speed change rate ΔNE in which the fuel cut is executed (in FIG. 3-2) as compared with the case where the control determination threshold value α is used. (Range indicated by D) is limited, so that the operation stop of the internal combustion engine 1 during the fuel cut can be more effectively avoided.

  The return speed enrt is constant regardless of the magnitude of the engine speed change rate ΔNE. However, as indicated by the one-dot chain line enrt1 and enrt2 shown in FIG. 3-2, the return speed enrt depends on the magnitude of ΔNE. You may change the engine speed which returns from a cut. As a result, the fuel cut and the fuel cut delay angle control can be executed more appropriately. Therefore, the fuel cut and the fuel cut return delay control are performed while avoiding the stop of the internal combustion engine 1 during the fuel cut execution. The range that can be executed can be further expanded. As a result, the fuel consumption of the internal combustion engine 1 can be further suppressed, and the range in which the shock at the time of return from the fuel cut can be suppressed can be further expanded. Next, the configuration of the fuel cut control device for an internal combustion engine according to the present embodiment will be described.

  FIG. 4 is an explanatory diagram showing a fuel cut control device for an internal combustion engine according to the present embodiment. Control regarding fuel cut of the internal combustion engine according to the present embodiment can be realized by using the fuel cut control device 10 of the internal combustion engine. As shown in FIG. 4, the fuel cut control device 10 for the internal combustion engine is built into the ECU 30. The ECU 30 includes a CPU (Central Processing Unit) 30P, a storage unit 30M, an input port 36 and an output port 37, and an input interface 38 and an output interface 39.

  In addition, separately from ECU30, the fuel cut control apparatus 10 of the internal combustion engine which concerns on this embodiment may be prepared, and this may be connected to ECU30. And in implement | achieving control regarding the fuel cut of the internal combustion engine which concerns on this embodiment, you may comprise so that the control function of the internal combustion engine 1 with which ECU30 is provided can use the said fuel cut control apparatus 10 of the said internal combustion engine. .

  The fuel cut control device 10 for an internal combustion engine according to the present embodiment includes a fuel cut condition determination unit 11, a fuel cut return control condition determination unit 12, and a fuel cut return control unit 13. Among these, the fuel cut condition determination unit 11, the fuel cut return control condition determination unit 12, and the fuel cut return control unit 13 execute control related to the fuel cut of the internal combustion engine that is the basis of the present embodiment. It becomes a part to do. In the present embodiment, the fuel cut control device 10 for an internal combustion engine is configured as a part of the CPU 30 </ b> P that constitutes the ECU 30. In addition, the CPU 30 </ b> P includes an engine control unit 30 </ b> C that controls the operation of the internal combustion engine 1.

And CPU30P, a storage unit 30M, are connected by a bus 35 _3. The internal combustion engine fuel cut control device 10 and the engine control unit 30C are connected via buses 35 ₁ and 35 _{2, an} input port 36 and an output port 37. Thereby, the fuel cut condition determination unit 11, the fuel cut return control condition determination unit 12, the fuel cut return control unit 13 and the engine control unit 30C constituting the fuel cut control device 10 of the internal combustion engine mutually control data. It can be exchanged and commands can be issued to one side. The internal combustion engine fuel cut control device 10 acquires data related to the operation control of the internal combustion engine 1 of the ECU 30, and controls the internal combustion engine fuel cut control device 10 to control the fuel cut of the internal combustion engine of the ECU 30. Routines can be interrupted.

  An input interface 38 is connected to the input port 36. The input interface 38 includes a crank angle sensor 41, an intake pipe pressure sensor 42, an air flow sensor 43, an accelerator opening sensor 44, a water temperature sensor 45, a vehicle speed sensor 46, and other various sensors that acquire information related to the operating state of the internal combustion engine 1. Is connected. Signals output from these sensors are converted into signals that can be used by the CPU 30P by the A / D converter 38a and the digital buffer 38d in the input interface 38 and sent to the input port 36. Thus, the CPU 30P can acquire information necessary for fuel supply control and operation control of the internal combustion engine 1.

  An output interface 39 is connected to the output port 37. The direct injection valve 3 and the ignition device 50 are connected to the output interface 39. Note that a control target (for example, an electronic throttle valve 70) 51 necessary for operation control of the internal combustion engine 1 is also connected to the output interface 39. The output interface 39 includes control circuits 39a, 39b and the like, and operates the control target based on a control signal calculated by the CPU 30P. With such a configuration, the CPU 30P of the ECU 30 can control the operation of the internal combustion engine 1 based on the output signals from the sensors.

  The storage unit 30M stores a computer program, a control map, and the like including a control processing procedure related to fuel cut of the internal combustion engine according to the present embodiment. Here, the storage unit 30M can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a flash memory, or a combination thereof.

  The computer program may be capable of realizing a control processing procedure related to fuel cut of the internal combustion engine according to the present embodiment, in combination with the computer program already recorded in the CPU 30P. The internal combustion engine fuel cut control device 10 uses dedicated hardware instead of the computer program, and includes a fuel cut condition determination unit 11, a fuel cut return control condition determination unit 12, and a fuel cut return control unit. 13 functions may be realized. Next, the control regarding the fuel cut of the internal combustion engine which concerns on this embodiment is demonstrated. In the following description, please refer to FIGS.

  FIG. 5 is a flowchart for explaining a control procedure related to fuel cut of the internal combustion engine according to the present embodiment. In executing control related to fuel cut of the internal combustion engine according to the present embodiment, the fuel cut condition determination unit 11 provided in the fuel cut control device (hereinafter referred to as fuel cut control device) 10 of the internal combustion engine is an engine control unit provided in the ECU 30. It is determined whether or not a fuel cut (F / C) is being executed based on the fuel injection command of 30C and information from the accelerator opening sensor 44 or the vehicle speed sensor 46 (step S101). When the fuel cut is not executed (step S101: No), the process returns to START and continues to monitor the operation state of the internal combustion engine 1.

  When the fuel cut (F / C) is being executed (step S101: Yes), the fuel cut condition determination unit 11 has the engine speed change rate ΔNE smaller than the first control determination threshold value F (α). Whether or not (step S102). ΔNE is calculated based on a change in the engine speed NE at a predetermined time Δt acquired from the crank angle sensor 41 by the fuel cut condition determination unit 11. When ΔNE ≧ F (α) is satisfied (step S102: No, the range of ΔNE ≧ F (α) in FIG. 3-2), the fuel cut condition determination unit 11 determines not to execute the fuel cut (step S103). . That is, the fuel cut return retardation control is not executed. In response to this determination, when the fuel cut is being executed, the engine control unit 30C of the ECU 30 stops the fuel cut being executed.

  When ΔNE <F (α) is satisfied (step S102: Yes, the range of ΔNE <F (α) in FIG. 3-2), the fuel cut condition determination unit 11 determines that the current engine speed NE and the return engine speed enrt. Are compared (step S104). If NE> enrt (step S104: No), the engine speed NE is still in the range where the fuel cut is executed, so the engine control unit 30C of the ECU 30 continues the fuel cut being executed (step S105).

  When NE ≦ enrt is satisfied (step S104: Yes), the condition is to return from the fuel cut to the internal combustion engine 1. In this case, it is necessary to return the internal combustion engine 1 from the fuel cut state, but it is necessary to determine whether or not to execute the fuel cut return retard control when returning from the fuel cut. Therefore, the fuel cut return control condition determination unit 12 of the fuel cut control device 10 determines whether or not the engine speed change rate ΔNE is smaller than the second control determination threshold value F (β) (step). S106).

  When ΔNE ≧ F (β) is satisfied (step S106: No, the range of F (α)> ΔNE ≧ F (β) in FIG. 3-2), when the fuel cut return retardation control is executed, ΔNE is large. That is, since the engine speed NE greatly decreases during the fuel cut, it is necessary to avoid the stop of the internal combustion engine 1. Accordingly, in this case, the fuel cut return control condition determination unit 12 prohibits the execution of the fuel cut return retard control (step S107), and when returning from the fuel cut, the operating condition of the internal combustion engine 1 at that time The internal combustion engine 1 is operated at the ignition timing required from As a result, the internal combustion engine 1 is reliably driven to avoid a stop.

  If ΔNE <F (β) (step S106: Yes, the range of ΔNE <F (β) in FIG. 3-2), there is a possibility that the shock at the time of return from the fuel cut exceeds the allowable value. Therefore, the fuel cut return control condition determination unit 12 determines to execute the fuel cut return retard control (step S108). In response to this determination, the fuel cut return control unit 13 of the fuel cut control device 10 calculates the retard amount of the ignition timing, and sets the ignition timing of the internal combustion engine 1 based on the retard amount. Then, in accordance with the return from the fuel cut, the fuel cut return control is executed (step S109). Next, a procedure for calculating the retard amount in the fuel cut return retard control will be described.

  FIG. 6 is a flowchart showing a procedure for calculating the retard amount in the fuel cut return control according to the present embodiment. FIG. 7 is an explanatory diagram showing an example of a map used for calculating the retard amount in the fuel cut return control according to the present embodiment. When executing the fuel cut return retard angle control, the fuel cut return control unit 13 of the fuel cut control device 10 applies pressure (hereinafter referred to as intake pipe pressure) Pi from the intake pipe pressure sensor 42 to the intake pipe 22 of the internal combustion engine 1. Is acquired (step S201). Then, the fuel cut return control unit 13 calculates the retard amount CA_r corresponding to the acquired intake pipe pressure Pi (step S202).

  In the present embodiment, as shown in the map 61 of FIG. 7, the retard amount CA_r is increased as the intake pipe pressure Pi becomes smaller (that is, the negative pressure in the intake pipe 22 becomes smaller than the atmospheric pressure). . That the intake pipe pressure Pi is small, that is, the negative pressure in the intake pipe 22 is smaller than the atmospheric pressure means that the load (or load factor) of the internal combustion engine 1 is large. When the load of the internal combustion engine 1 is large, the internal combustion engine 1 sucks in a lot of air when returning from the fuel cut, and more fuel is supplied correspondingly. As a result, the engine speed NE increases more rapidly, and the shock transmitted to the vehicle 100 and its passengers also increases.

  For this reason, in this embodiment, the retard amount CA_r is changed according to the intake pipe pressure Pi. More specifically, as the intake pipe pressure Pi decreases, the retard amount CA_r is increased, thereby further suppressing the torque generated by the internal combustion engine 1 and suppressing the rapid increase in the engine speed NE. Reduce the shock transmitted to 100 and its occupants. As described above, since the accuracy of estimating the load (load factor) of the internal combustion engine 1 is improved by using the intake pipe pressure, the amount of retardation corresponding to the load of the internal combustion engine 1 can be accurately determined. As a result, the sudden increase in the engine speed NE can be effectively suppressed, and the shock transmitted to the vehicle 100 and its occupant can be effectively reduced. Further, by using the intake pipe pressure Pi that reacts sensitively to load fluctuations of the internal combustion engine 1 with a highly responsive pressure sensor (intake pipe pressure sensor 42), control responsiveness can be improved. Furthermore, since a necessary and sufficient amount of retardation can be set, when the load on the internal combustion engine 1 is small, the amount of retardation can be minimized to improve the response of the internal combustion engine 1.

  When the retard amount CA_r corresponding to the acquired intake pipe pressure Pi is calculated (step S202), the fuel cut return control unit 13 determines the ignition timing (MBT: Minimum as much as possible) determined based on the operating conditions of the internal combustion engine 1. The ignition timing of the internal combustion engine 1 is retarded by the calculated retard amount CA_r. The fuel cut return control unit 13 executes the fuel cut return delay control in accordance with the time when the internal combustion engine 1 returns from the fuel cut, using the ignition timing delayed by the delay amount CA_r as the ignition timing at the time of return. (Step S203).

  In the procedure for determining the retard amount in the fuel cut return retard control described above, the first control determination threshold value F (α) and the second control determination threshold value F (β) are set according to the engine speed NE. The present invention can be applied to other than the control related to the fuel cut to be changed. Next, from the determination at the time of executing the fuel cut return retard control, the delay amount is determined according to the intake pipe pressure Pi in the fuel cut return retard control, and the fuel cut return retard control is executed. A series of procedures will be described.

  FIG. 8 is a flowchart showing a procedure for calculating the retard amount in the fuel cut return control according to the present embodiment. In calculating the retard amount in the fuel cut return retard control, the fuel cut return control unit 13 of the fuel cut control device 10 receives the coolant temperature of the internal combustion engine 1 from the water temperature sensor 45 (see FIGS. 1 and 2, etc.). Tw is acquired and compared with the fuel cut execution determination water temperature Tw_c (step S301). If the cooling water temperature Tw of the internal combustion engine 1 has not reached the fuel cut execution determination water temperature Tw_c, the fuel cut itself is not executed. In step S301, a precondition for executing the fuel cut return retard control is determined.

  When Tw <Tw_c (step S301: No), the fuel cut itself is not executed, so that the fuel cut return delay control is prohibited (step S309). When Tw ≧ Tw_c (step S301: Yes), the fuel cut return control unit 13 acquires the vehicle speed V of the vehicle 100 (see FIG. 2) from the vehicle speed sensor 46 and compares it with the fuel cut execution determination vehicle speed Vc ( Step S302). If the vehicle speed V of the vehicle 100 on which the internal combustion engine 1 is mounted does not reach the fuel cut execution determination vehicle speed Vc, the fuel cut itself is not executed. Therefore, in step S302, a precondition for executing the fuel cut return retard control Determine.

  If V <Vc (step S302: No), the fuel cut itself is not executed, so that the fuel cut return retard control is prohibited (step S309). When V ≧ Vc, the fuel cut return control unit 13 acquires the accelerator opening from the accelerator opening sensor 44 and determines whether or not the accelerator is ON (step S303). When the accelerator is stepped on (that is, the accelerator is ON), the driver of the vehicle 100 has the intention of accelerating the vehicle 100 and therefore does not perform the fuel cut. For this reason, in step S303, a precondition for executing the fuel cut return retardation control is determined.

  When the accelerator is ON (step S303: No), the fuel cut itself is not executed, so that the fuel cut return retard control is prohibited (step S309). When the accelerator is OFF (step S303: Yes), the fuel cut return control unit 13 determines whether there is a fuel cut request from the automatic transmission (AT) 55 (see FIGS. 1 and 2) (see FIG. 1). Step S304). Depending on the gear position of the automatic transmission 55, the fuel cut may not be executed. Therefore, in step S304, a precondition for executing the fuel cut return retardation control is determined. In step S304, for example, the fuel cut return control unit 13 acquires the gear position of the automatic transmission 55, and based on this, the fuel cut return control unit 13 determines whether there is a request for fuel cut. Moreover, based on the request | requirement from the control apparatus of the automatic transmission 55, the fuel cut return time control part 13 may determine the presence or absence of the request | requirement of a fuel cut.

  When there is no fuel cut request from the automatic transmission 55 (step S304: No), the fuel cut itself is not executed, and thus the fuel cut return delay angle control is prohibited (step S309). When there is a fuel cut request from the automatic transmission 55 (step S304: Yes), the fuel cut return control unit 13 determines whether there is a request for natural return (step S305). The natural return is a case where the engine speed change rate ΔNE is smaller than the first control determination threshold value F (α) and the engine speed NE is equal to or lower than the return speed enrt. In the non-natural recovery, for example, the engine speed change rate ΔNE becomes equal to or higher than the first control determination threshold value F (α) during the fuel cut, so that the internal combustion engine 1 is prevented from being stopped. This is a case where cutting is stopped.

  If there is no request for natural return (step S305: No), the fuel cut itself is not executed, so that the fuel cut return retard control is prohibited (step S309). When there is a request for natural return (step S305: Yes), the fuel cut return control unit 13 acquires the pressure (hereinafter referred to as intake pipe pressure) Pi in the intake pipe 22 of the internal combustion engine 1 from the intake pipe pressure sensor 42. (Step S306). Then, the fuel cut return control unit 13 calculates a retard amount CA_r corresponding to the acquired intake pipe pressure Pi (step S307), and the fuel cut return delay in accordance with the return of the internal combustion engine 1 from the fuel cut. Control is executed (step S308).

  The following invention is grasped | ascertained from the said embodiment. According to a first aspect of the present invention, when executing the control for retarding the ignition timing of the internal combustion engine when the supply of fuel is resumed from the fuel cut state, the control is performed based on the pressure in the intake pipe of the internal combustion engine. A fuel cut control device for an internal combustion engine that sets a retard amount of an ignition timing of the internal combustion engine.

  This fuel cut control device for an internal combustion engine changes the retard amount when resuming the supply of fuel according to the pressure in the intake pipe. Thus, since the pressure in the intake pipe is used when determining the retard amount, the estimation accuracy of the load (load factor) of the internal combustion engine is improved, and the retard amount corresponding to the load of the internal combustion engine is accurately determined. can do. As a result, it is possible to effectively suppress a sudden increase in the engine speed and effectively reduce the shock transmitted to the vehicle and its occupant. Further, the control responsiveness can be improved by using the pressure in the intake pipe that reacts sensitively to the load fluctuation of the internal combustion engine.

  A second invention is the fuel cut control device for an internal combustion engine according to the first invention, wherein the retard amount is increased as the pressure in the intake pipe of the internal combustion engine decreases. As described above, the retard amount is increased as the pressure in the intake pipe decreases. Therefore, when the pressure in the intake pipe is small, that is, when the load of the internal combustion engine is large, the retard amount is increased. The torque of the internal combustion engine can be further suppressed. Thereby, it is possible to more effectively suppress the rapid increase in the engine speed, and to effectively reduce the shock transmitted to the vehicle and its occupant.

  As described above, in the present embodiment, it is determined whether or not the fuel cut is to be executed by comparing the rate of change of the engine speed with the first control determination threshold value that is changed according to the engine speed. Further, it is determined whether or not to execute the retard of the ignition timing when returning from the fuel cut by comparing the rate of change of the engine speed with a second control determination threshold value that is changed according to the engine speed. judge. As a result, fuel cut and fuel cut retard control can be executed more appropriately, so that the fuel cut can be executed and the fuel cut return retard control while avoiding the stop of the internal combustion engine 1 during the fuel cut. Can be expanded. As a result, the fuel consumption of the internal combustion engine can be suppressed, and the range in which the shock at the time of return from the fuel cut can be suppressed is expanded.

  As described above, the fuel cut control device for an internal combustion engine according to the present invention is useful for fuel cut for a spark ignition type internal combustion engine, and in particular, supplies fuel from a range where the fuel cut can be performed and from the state of the fuel cut. It is suitable for expanding the range in which the ignition timing can be retarded when resuming.

It is sectional drawing which shows the internal combustion engine which concerns on this embodiment. It is a mimetic diagram showing the state where the internal-combustion engine concerning this embodiment was carried in vehicles. It is a figure for demonstrating the control regarding the fuel cut of the internal combustion engine which concerns on this embodiment. It is a figure for demonstrating the control regarding the fuel cut of the internal combustion engine which concerns on this embodiment. It is explanatory drawing which shows the fuel cut control apparatus of the internal combustion engine which concerns on this embodiment. It is a flowchart explaining the procedure of the control regarding the fuel cut of the internal combustion engine which concerns on this embodiment. It is a flowchart which shows the calculation procedure of the retard amount in the fuel cut reset control which concerns on this embodiment. It is explanatory drawing which shows an example of the map used for calculation of the amount of retardation in the fuel cut reset control which concerns on this embodiment. It is a flowchart which shows the calculation procedure of retardation amount in the fuel cut reset control which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Direct injection valve 4 Connecting rod 5 Piston 6 Crankshaft 7 Spark plug 10 Fuel cut control device 11 Fuel cut condition determination part 12 Fuel cut return control condition determination part 13 Fuel cut return control part 22 Intake pipe 30C Engine control unit 41 Crank angle sensor 42 Intake pipe pressure sensor 43 Air flow sensor 44 Accelerator opening sensor 45 Water temperature sensor 46 Vehicle speed sensor 50 Ignition device 55 Automatic transmission 61 Map 70 Electronic throttle valve 100 Vehicle

Claims (3)

Controls the execution of fuel cut for the internal combustion engine and the restart of fuel supply ,
And the rotation speed of the change rate of the previous SL internal combustion engine, wherein by comparing the first control determination threshold value is changed according to the engine speed, determines the fuel cut condition determining whether to execute a fuel cut and parts,
The engine speed is compared with the return speed, and when the engine speed is equal to or lower than the return speed, it is determined that the fuel supply is resumed from the fuel cut state, and the fuel is cut from the fuel cut state. If it decides to supply resume compares the rotation speed of the change rate of the previous SL internal combustion engine, and a second control determination threshold value is changed according to the engine speed, the ignition timing A fuel cut return control condition determination unit that determines whether or not to execute control to retard the angle,
When it is determined that the ignition timing retard control is to be executed, the retard amount of the ignition timing of the internal combustion engine is set, and when returning from the fuel cut, the fuel cut is ignited based on the set retard amount A return control unit;
Only including said first control determination threshold value and the second control determination threshold value, the fuel cut control apparatus for an internal combustion engine, wherein the smaller with a decrease in the engine speed. The fuel cut recovery control unit
On the basis of the pressure in the intake manifold of an internal combustion engine, fuel cut control apparatus for an internal combustion engine according to claim 1, characterized in that for setting the retard amount. The fuel cut control device for an internal combustion engine according to claim 2 , wherein the retard amount is increased as the pressure in the intake pipe of the internal combustion engine decreases.

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