JPH051578A - Deceleration control system of internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce a free running state at the time of deceleration as well as to secure a good drive feeling by making a valve opening period of an intake valve larger than the specified valve opening period at the time of detecting a decelerated state, while controlling the opening of a throttle valve being controlled electrically to be smaller than the specified opening. CONSTITUTION:A throttle valve 2 being controlled of its opening or closing by an actuator 3 is installed in a manifold part 1a of an intake pipe 1, and a bypass valve 7 is installed in the point midway in a bypass pipe 6 bypassing this throttle valve 2. In addition, an intake valve 15 is attached to an intake port at each cylinder, and it is controlled by a hydraulic driving valve unit. As these valves 2, 7 and this hydraulic driving valve unit are all controlled by a engine control unit 4, when an engine's decelerated state is detected, a valve opening period of the intake valve 15 is made larger than the specified valve opening period, while opening of the throttle valve 2 is controlled to be smaller than the specified opening. In succession, the valve opening period of the intake valve 15 till the valve opening period of the throttle valve 2 becomes smaller than the specified opening at this deceleration control time is made smaller than a second specified valve opening period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deceleration control method for an internal combustion engine, and more particularly to a method for enhancing an engine braking effect during deceleration.

[0002]

2. Description of the Related Art In recent years, in order to improve the controllability of an internal combustion engine, a throttle valve is configured to be driven by an actuator such as a stepping motor, and controlled in accordance with the accelerator pedal depression amount or depression speed and engine operating parameters. A technique has been proposed in which means controls the opening of a throttle valve by controlling the actuator (for example, Japanese Patent Laid-Open No. 02-169838).

[0003]

However, in the above-described actuator-driven internal combustion engine, the stepping motor as an actuator has a throttle valve drive speed in which the accelerator pedal and the throttle valve, which are generally used conventionally, are mechanically connected to each other. It is slower than in the case of driving, and for example, it takes about 1 second from full valve opening to full valve closing. Further, it is difficult to increase the driving speed of the stepping motor in relation to the control accuracy of the valve opening.

As described above, when it takes time to fully open the throttle valve from fully open, the negative pressure in the intake pipe rises slowly, and the engine brake does not work during deceleration of the engine (hereinafter referred to as "idling state"). Is called),
It is assumed that the driving feeling is not favorable.

The present invention has been made in view of the above circumstances, and relates to a deceleration control method for an internal combustion engine capable of reducing idle conditions during deceleration and obtaining a good driving feeling.

[0006]

In order to achieve the above object, the present invention provides a deceleration control method for an internal combustion engine having an intake valve whose valve opening period can be arbitrarily changed and an electrically operated throttle valve. When the deceleration state of the engine is detected, the deceleration control is performed such that the opening period of the intake valve is made longer than a predetermined opening period and the opening of the throttle valve is made smaller than a predetermined opening. An internal combustion engine, wherein an opening period of the intake valve is set to be shorter than a second predetermined opening period shorter than the predetermined opening time until the opening of the throttle valve becomes smaller than the predetermined opening. The deceleration control method is provided.

Further, in a deceleration control method for an internal combustion engine having an intake valve whose valve opening period can be changed arbitrarily and an electrically operated throttle valve, a deceleration state of the engine and a stop of fuel supply to the engine. When the states are simultaneously detected, deceleration control is performed such that the opening period of the intake valve is made longer than a predetermined opening period and the opening of the throttle valve is made smaller than a predetermined opening. The deceleration control method for an internal combustion engine, characterized in that the valve opening period of the intake valve is set to be smaller than a second predetermined valve opening period which is shorter than the predetermined valve opening time until the valve opening amount of is smaller than the predetermined valve opening amount. I will provide a.

[0008]

In the deceleration control method for the internal combustion engine according to the present invention, when the deceleration state of the engine is detected, the opening period of the intake valve is made longer than the predetermined opening period and the opening degree of the throttle valve is set to the predetermined opening degree. Make it smaller. This creates an engine braking condition due to pumping loss. At this time, the opening period of the intake valve is made shorter than the predetermined opening period until the opening of the throttle valve becomes smaller than the predetermined opening. As a result, the intake air is prevented from flowing into the combustion chamber, and the idling state during deceleration is reduced. In particular, by performing the deceleration control when the fuel supply to the engine is stopped, it is not necessary to control the fuel supply during the deceleration control, and the deceleration control can be easily and reliably performed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing an example of the overall configuration of an internal combustion engine to which the deceleration control method for an internal combustion engine according to the present invention is applied. In FIG. 1, a collecting portion 1a of the intake pipe 1
Is provided with a throttle valve 2, and an actuator 3 including, for example, a stepping motor is connected to the throttle valve 2. The actuator 3 is connected to an electronic control unit (hereinafter referred to as “ECU”) 4,
The throttle valve 2 is driven according to the control signal from U4. A throttle valve opening (θTH) sensor 5 is mechanically connected to the throttle valve 2 and a detection signal thereof is supplied to the ECU 4.

An air cleaner 3 is provided at the upstream end of the collecting portion 1a of the intake pipe 1. A bypass pipe 6 that bypasses the throttle valve 2 is connected between the collecting portion 1a of the intake pipe 1 and a branch portion 1b on the downstream side thereof, and a bypass valve 7 including a linear solenoid or the like is provided in the middle of the bypass pipe 6. Is provided. The bypass valve 7 is opened / closed by a signal from the ECU 4.

At the branch portion 1b of the intake pipe 1, the intake air temperature (T
A) A sensor 8 and an intake pipe absolute pressure (PB) sensor 9 are mounted, and their detection signals are supplied to the ECU 4. Furthermore,
A vacuum tank 10 for accumulating negative pressure in the intake pipe is connected to a branch portion 1b of the intake pipe 1 via a check valve 11. The negative pressure sensor 12 is the vacuum tank 10.
The internal negative pressure is detected and the detection signal is supplied to the ECU 4. The negative pressure accumulated in the vacuum tank 10 is the pipe 10
It is supplied to each device of the engine which needs a negative pressure by a.
Further, a fuel injection valve 13 is attached to the branch portion 1b of the intake pipe 1, and injects fuel while being biased for a valve opening time period according to a control signal from the ECU 4.

An intake valve 15 is attached to an intake port 24 between the intake pipe 1 and each cylinder 14 of the cylinder block of the engine, and a control signal from the ECU 4 causes a hydraulic drive valve unit 30 (FIG. 2) described later to intervene. The valve opening period (valve opening timing and / or valve closing timing) is controlled. On the other hand, the exhaust pipe 16
An exhaust valve 17 is attached to an exhaust port between each cylinder 14 and each cylinder 14, and a valve opening period is controlled by a control signal from the ECU 4 via a hydraulically driven valve unit (not shown).

A (TW) sensor 18 is inserted into the water jacket on the peripheral wall of the cylinder 14 of the engine, and the detection signal thereof is supplied to the ECU 4. Also, the engine speed (N
E) A sensor 19 is arranged so as to face the crankshaft of the engine, and a pulse signal (TDC) is output at each predetermined crank angle of each cylinder.
Signal) and supplies it to the ECU 4.

The hydraulic pressure (Toi1) sensor 20 detects the temperature of the hydraulic oil of the hydraulic drive unit 30 and outputs the detection signal as E.
Send to CU4.

An O ₂ sensor 21 is attached to the exhaust pipe 16 to detect the oxygen concentration in the exhaust gas and output the detection signal to the ECU.
Supply to 4. Further, a three-way catalyst 15 for purifying exhaust gas is arranged downstream of the O ₂ sensor 21 in the exhaust pipe 16.

Further, the ECU 4 is provided with an accelerator opening sensor 6 for detecting the accelerator pedal depression amount (θACC) as a parameter representing the driver's request to the engine.
0, an atmospheric pressure sensor 61 that detects the atmospheric pressure (PA), and a vehicle speed sensor 62 that detects the traveling speed (V) of a vehicle equipped with an engine are electrically connected, and the detection signals of these sensors are It is supplied to the ECU 4. The ECU 4 is a central processing unit, a memory, a control signal output circuit, etc. (not shown)
The hydraulic drive valve unit 30 and the like are controlled based on detection signals from various sensors and the ignition timing is controlled, and the opening time of the fuel injection valve 13 is controlled.

FIG. 12 is a sectional view of the hydraulically driven valve unit 30. The unit 30 is mounted on the cylinder head 14a of each cylinder 14 of the engine. The cylinder head 14a has an intake valve port 23 that opens at the top of the combustion chamber 14b (FIG. 1) of the engine and the other communicates with the intake port 24.
Is provided. The intake valve 15 is arranged so as to be movable in the vertical direction in the figure in the cylinder head 14a so as to open and close the intake valve port 23. A valve spring 26 is contracted between the flange portion 25 of the intake valve 15 and the cylinder head 14a. The valve spring 26 biases the intake valve 15 upward (in the valve closing direction) in the drawing. It

On the other hand, on the left side of the intake valve 15 in FIG.
A cam shaft 28 having 7 is rotatably arranged. The cam shaft 28 is connected to a crank shaft (not shown) via a timing belt (not shown). Cam shaft 2
A hydraulic drive valve unit 30 is interposed between the cam 27 integrally formed with the intake valve 8 and the intake valve 15.

The hydraulic drive valve unit 30 presses the intake valve 15 downward against the valve spring 26 according to the profile of the cam 27 to open and close the hydraulic drive mechanism 30A, and the pressing force of the hydraulic drive mechanism 30A. Disable during the valve opening operation,
Therefore, the hydraulic pressure release mechanism 30B closes the intake valve 15 regardless of the cam profile.

The hydraulic drive mechanism 30A includes the cylinder head 2
The first cylinder body 33 fixed to the block 32 formed integrally with the first cylinder body 33 and the lower end (front end) of the first cylinder body 33 are brought into contact with the upper end (rear end) of the intake valve 15 so that the cylinder hole 33a of the first cylinder body 33 is formed. A valve-side piston (valve-driving piston) 34 slidably fitted to the valve, an operating hydraulic chamber 38 defined by the first cylinder body 33 and the valve-side piston 34, and a block 3
2, a second cylinder body 36 fixed to the second cylinder body 36, a lifter 35 slidably contacting the cam 27, and a lower end of the lifter 35 abutted to be slidably fitted to a lower portion of the second cylinder body 36. Main components are a cam side piston 37, a hydraulic pressure generation chamber 39 defined by the second cylinder body 36 and the cam side piston 37, and an oil passage 40 that connects the hydraulic pressure generation chamber 39 and the working hydraulic pressure chamber 38. Then, when the hydraulic pressure in the working hydraulic chamber 38 is equal to or higher than a predetermined value, the intake valve 1 follows the profile of the cam 27.
Open and close 5

The block 32 includes a collar portion 25 of the intake valve 15.
A lift sensor 62 is arranged at a position facing to.
The lift sensor 62 is electrically connected to the ECU 4, detects the lift amount of the intake valve 15, and outputs the detection signal as E.
Supply to CU4.

On the other hand, the hydraulic pressure release mechanism 30B is provided in the oil passage 4
0 and the oil supply gallery 42, an oil passage 41, a spill valve 45 interposed in the oil passage 41, a feed valve 43 and a check valve 44 arranged in the oil passage 41, and these valves. The main constituent elements are an accumulator 46 for holding the released hydraulic pressure in the accumulator circuit 41a defined by 43 and 44 and the spill valve 45. Spill valve 4
The solenoid 45a of No. 5 is connected to the ECU 4 and is excited and demagnetized by its control signal. The oil supply gallery 42 is provided to supply hydraulic pressure to the hydraulically driven valve unit provided for each cylinder, and is connected to the oil pump 47. The oil pump 47 supplies the hydraulic oil in the auxiliary oil pan 48 provided in the cylinder head 21 to the oil supply gallery 42 as a hydraulic pressure within a predetermined range. The hydraulic oil supplied to the oil supply gallery 42 may be supplied by an oil pump from an oil pan provided under a crankcase (not shown).

The accumulator 46 is a hydraulic release mechanism 30.
A cylinder hole 461 provided in the middle of the accumulator circuit 41a for accumulating the hydraulic pressure and the exhaust oil released by the spill valve 45 of B, and the air hole 4 formed in the block 32.
A cap 463 having 62, a piston 464 slidably fitted in the cylinder hole 461, and a cap 463.
And a spring 465 contracted between the piston 464 and the piston 464.

Details of the configurations of the hydraulic drive mechanism 30A and the hydraulic release mechanism 30B are described in Japanese Patent Laid-Open No. 01-91352.

The hydraulic drive mechanism 30 configured as described above
The operation of A and the hydraulic pressure release mechanism 30B will be described below.

When the solenoid 45a of the spill valve 45 is excited by the control signal from the ECU 4, the spill valve 45 is closed and the hydraulic pressure generating chamber 39, the hydraulic passage 40 and the working hydraulic chamber 38 of the hydraulic drive mechanism 30A are closed. Is maintained at a high pressure equal to or higher than a predetermined value, and the intake valve 15 is opened / closed according to the profile of the cam 27. Therefore, the valve operating characteristics in this case (relationship between crank angle and valve lift)
Is shown by the solid line in FIG.

On the other hand, when the intake valve 15 is opened, the solenoid 45a of the spill valve 45 is controlled by a control signal from the ECU 4.
Is demagnetized, the spill valve 45 is opened, the hydraulic pressure in the hydraulic pressure generating chamber 39, the hydraulic passage 40, and the working hydraulic chamber 38 of the hydraulic drive mechanism 30A decreases, and the intake valve irrespective of the profile of the cam 27. 15 starts the valve closing operation. At this time,
By the hydraulic oil return amount limiting mechanism provided in the valve side piston 34, the valve closing speed of the intake valve 15 is relaxed during the valve closing operation, and the intake valve 15 is gently seated on the valve seat 21a. The valve operating characteristic in this case is as shown by the broken line in FIG. That is, in the figure, the solenoid 45 is operated with the crank angle θOFF.
When a is demagnetized, it will be slightly delayed from θOFF (θ = θS
T) The intake valve 15 starts the valve closing operation, and is in the valve closing completed state at θ = θIC.

As described above, by opening and closing the spill valve 45 by the control signal from the ECU 4 and invalidating the action of the hydraulic drive mechanism 30A when the valve is opened,
The valve closing start timing (valve closing timing) of the intake valve 15, and thus the valve opening period, can be arbitrarily set. As a result, the intake air amount of each cylinder can be controlled by the control signal of the ECU 2.

In this embodiment, a hydraulically driven valve unit (not shown) similar to that on the intake valve side is provided on the exhaust valve side, but the exhaust valve side is normally closed at a constant timing according to the cam profile. Alternatively, a variable valve timing mechanism capable of setting a plurality of valve opening / closing timings may be used.

Next, an embodiment of a deceleration control method for an internal combustion engine according to the present invention will be described with reference to FIGS.

4 and 5 are flow charts showing an embodiment. First, engine speed NE and accelerator opening θA
CC, throttle valve opening θTH, engine cooling water temperature T
W, hydraulic oil temperature Toi1 of the hydraulically driven valve unit 30, negative pressure in the intake pipe (hereinafter referred to as "intake pressure") PB, and vehicle speed V
The respective values of are read from the sensors 19, 60, 18, 20, 9, and 62 of FIG. 1 (step S1).

Next, it is detected whether or not the engine is in the decelerating state (step S2). The deceleration state is detected using the tables shown in FIGS. 6 to 8,
DR1, DR3, and DR5 are areas determined to be in a deceleration state,
DR2, DR4, and DR6 are areas that are not determined to be in a decelerated state. In FIG. 6, the horizontal axis represents the accelerator opening θACC,
The vertical axis represents the engine speed NE. As shown in the figure,
Basically, when NE is high and θACC is small, it is determined that the vehicle is in the decelerated state, and when NE is lower than a predetermined value or when θACC is greater than the predetermined value, the vehicle is not determined to be in the decelerated state. See also FIG.
Where the horizontal axis represents the accelerator opening θACC and the vertical axis represents the vehicle speed V
Indicates. As shown in the figure, V is basically large and θA
If CC is small, it is determined that the vehicle is in a decelerated state, and if θACC is smaller than a predetermined value, it is determined that the vehicle is in a decelerated state regardless of V. Further, in FIG. 8, the horizontal axis represents the accelerator opening speed ΔθACC, and the vertical axis represents the engine speed NE. As shown in FIG.
Is within the predetermined range and ΔθACC is within the predetermined range of a large negative value, it is determined that the vehicle is in the deceleration state. This is because the state where ΔθACC is in the predetermined range of a large negative value is when the accelerator pedal is suddenly released, and in this state, the driver requests deceleration. ΔθACC is θAC for each output signal (crank angle signal) pulse of the engine speed sensor 19, for example.
The C value may be read and determined from the difference in the θACC value between the time when the pulse was generated several times ago and the time when the current pulse was generated, or may be determined from the difference in the θACC value read for each pulse of a constant cycle. This deceleration determination is to determine that the region DR2 ′ in FIG. 6 is also in the decelerated state when ΔθACC is a large negative value, and in the region DR2 ′ in FIG. 6, the accelerator opening θACC is set.
Is not less than the specified value, the deceleration processing will not be performed.
By using the discrimination of FIG. 8, there is an effect that the deceleration state is discriminated early even if θACC is equal to or larger than the predetermined value. As a method of determining whether or not the vehicle is in the deceleration state, each sensor value is set to the area D.
When either one or both of R1 and DR3 is indicated, each sensor value indicates either one of the regions DR1 and DR3 or indicates DR5, or
There is a method of discriminating the deceleration state when each sensor value indicates both the regions DR1 and DR3 or indicates the region DR5.

Returning to FIGS. 4 and 5, when it is determined in step S2 that the engine is in the deceleration state, the engine is in the fuel cut (F / F /
C) It is determined whether or not it is in the area (step S3). This determination is performed using FIG. In FIG. 9, the horizontal axis represents the engine cooling water temperature TW or the oil temperature Toi1, the vertical axis represents the engine speed NE, DR7 is a region determined to be the F / C region, and DR8 is a region not determined to be the F / C region. is there. As shown in the figure, as the TW or Toi1 is higher, that is, the higher the engine temperature, the lower NE is determined as the F / C region.

If the F / C area is determined in step S3, fuel cut is executed (step S4). In this way, by executing the fuel cut, it is not necessary to control the fuel during the deceleration control, and the valve opening time of the intake valve 15 described later can be controlled by considering only the engine braking effect (FIG. 13). Engine deceleration control can be performed easily and reliably.

Next, the throttle valve opening command value THCMD
1 is output to the actuator 3 of FIG. 1 as the target throttle valve opening value THTRG during deceleration (step S
5, S6). The target value THTRG is determined according to the engine speed NE as shown in FIG. 10, but its characteristic curve varies depending on the type of engine and the like, as shown by the solid line, broken line, and chain line in the figure. The target value THTRG is NE = NE1 and θT when the throttle valve opening θTH is set to THTRG in the state of deceleration engine speed NE> NE1.
If H = THTRG1, the intake valve closing timing is set to a value such that an engine braking state can be created by setting a target value OFF MAP described later.

Next, the throttle valve opening θTH is the target throttle valve opening value THTRG + the predetermined opening value ΔTHT during deceleration.
It is determined whether or not RG (for example, 0.5 degree) or less (step S7), and if θTH> THTRG + ΔTHTRG, from ΔθTH = θTH-THTRG, the target valve closing timing of this time (closing time). θOFFTMG (n)
Is searched (steps S8 and S9). This θOFFTM
The G (n) search is performed by the OFFTR vs. ΔθTH table of FIG. 11, and the OFFTR corresponding to ΔθTH is obtained.
This OFFTR is set to θOFFTMG (n). Figure 11
As shown in, if the value of ΔθTH is small, θTH is TH
Since it is close to TRG, it is possible to open the intake valve to some extent and enter the engine braking state. OFFTRO in FIG. 11 is Δ
It is a valve opening period (predetermined valve opening period) of the intake valve 15 when θTH = 0.

Next, the flag FLG is set to "0" (step S10). The flag FLG is set in step S described later.
In 13, the closing period of the intake valve 15 is the target closing timing θOFFT.
Set to "1" when set to MG (step S
14). Next, the output routine of the target valve closing timing θOFFTMG is executed (step S11).

On the other hand, if it is determined in steps S2 and S3 that the engine is not in the decelerating state, or if it is in the decelerating state but not in the F / C region, the flag FLG is set.
Is set to "0" (step S10) and the output routine is executed (step 11). In this case, the target valve closing timing θOFFTMG of the intake valve 15 is θO during normal operation (not shown).
Determined by the FFTMG determination routine. In the above output routine, the .theta.OFFTMG value is further corrected according to the engine speed NE, the oil temperature Toil, etc., and converted into the spill valve 45 control signal to be output.

Further, in step S7, θTH ≦ THTRG
When + ΔTHTRG is reached, the process proceeds to step S12, and it is determined whether or not the flag FLG is “0”. Since FLG is “0” at first, the target closing timing θOFFTMG (n) of the intake valve 15 is set to OFFMA.
P is set (step S13), the flag FLG is set to "1" (step S14), and the process proceeds to step S11. The value of OFFMAP is obtained from the table shown in FIG. As shown in the figure, the value of OFFMAP is a value corresponding to the value of the engine speed NE, and is a fully open value at a predetermined speed or lower. The reason why the intake valve 15 is not fully opened when NE is high is that if the valve is fully opened, the intake pressure PB becomes too large and the effect of engine braking becomes abrupt, which may reduce the driving feeling.

If the flag FLG is set to "1" instead of "0" in step S12, the process proceeds to step S15, and the value of the intake pressure PB (negative pressure) and the target pressure PAC during deceleration are set.
It is determined whether or not the absolute value of the difference from the OFF value is | PB-PACOFF | Target pressure PACOFF
Is provided in order to prevent the engine oil from rising into the engine combustion chamber due to the generation of excessive negative pressure and increasing the amount of blow bai.
Steps S21 to S21 are processing flows for bringing the value of the intake pressure PB close to the value of the target pressure PACOFF.

If │PB-PACOFF│> α,
Next, it is determined whether or not PB-PACOFF> 0 (step S16), and it is not PB-PACOFF> 0, that is, PB-P.
When ACOFF ≦ 0, the value of the intake pressure PB is smaller than the value of the target pressure PACOFF during deceleration, so θOFFTRM
G (n) is the previous intake valve target valve closing timing θOFFTMG
Since it is slower than (n-1), θOFFTMG (n) =
θOFFTMG (n-1) -β (PB-PACOFF)
(Step S17). The value of the correction coefficient β is obtained from the table of FIG. As shown in the figure, the value of β is NE
The higher is the smaller. This is because the higher the NE, the greater the pumping action of the engine. Therefore, the higher the NE, the earlier the intake valve closing timing for controlling the PB value should be corrected, that is, the opening period should be shortened. This is because the lower NE is, it is necessary to correct the intake valve closing timing in the later direction, that is, in the larger opening direction.

Next, it is determined whether or not the value of θOFFTMG (n) is less than or equal to the limit value (step S18), and if it is less than the limit value, the value of θOFFTMG (n) is left as it is and the process proceeds to step S14 to set the flag. Set FLG to "1". If the value of θOFFTMG (n) exceeds the limit value, the value of θOFFTRMG (n) is set as the limit value and the process proceeds to step S14 (step S19). This prevents a sudden change in the opening period of the intake valve.

In step S15, | PB-PACOFF |
When ≦ α, the value of the intake pressure PB is an appropriate value, and therefore the value of the intake valve target opening angle θOFFTMG (n) this time is the same as the previous valve opening angle θOFFTMG (n-1) ( In step S20), the value of the intake pressure PB is maintained at the previous value.

In step S16, PB-PACOFF> 0
In this case, the value of the intake pressure PB (negative pressure) is large, so the bypass valve 7 in FIG. 1 is opened (step S21), and the intake pressure P
Decrease the value of B. This is because the bypass valve 7 has better controllability of response and the like than the throttle valve 2, but of course, instead of the bypass valve 7, the opening degree of the throttle valve 2 may be controlled in the opening direction by a predetermined amount. However, both the bypass valve 7 and the throttle valve 2 may be controlled.

In the above embodiment, steps S8 and S
9 Incremental intake valve target opening angle θOFFTMG from ΔθTH
Although (n) is obtained, the value of θOFFTMG (n) may not be obtained from ΔθTH and may be a value in the fully closed state of the intake valve. That is, for example, as shown by the solid characteristic curve in FIG. 10, the engine speed NE decreases to NE1 (for example, 2000 rpm),
The throttle valve opening θTH is THTRG1 = THTRG +
The intake valve 15 may be fully closed until ΔTHTRG, and the closing timing of the intake valve 15 may be controlled in step S12 and subsequent steps when θTH ≦ THTRG1.

[0047]

As described above, the present invention provides a deceleration control method for an internal combustion engine having an intake valve whose valve opening period can be arbitrarily changed and an electrically operated throttle valve. When it detects that the throttle valve opening period of the intake valve is longer than a predetermined opening period and the throttle valve opening degree is smaller than the predetermined opening degree, the deceleration control is performed. The opening degree of the intake valve is made smaller than a second predetermined opening period which is shorter than the predetermined opening time until the degree of opening becomes smaller than the predetermined opening degree. Until that time, the intake valve can be controlled to be fully closed or to a predetermined opening time near it, so the influence of the drive delay of the throttle valve can be eliminated and the idling state during deceleration can be reduced. It can be made a driving feeling good.

Further, in a deceleration control method for an internal combustion engine having an intake valve whose valve opening period can be changed arbitrarily and an electrically operated throttle valve, the deceleration state of the engine and the stop of fuel supply to the engine. When the states are simultaneously detected, deceleration control is performed such that the opening period of the intake valve is made longer than a predetermined opening period and the opening of the throttle valve is made smaller than a predetermined opening. While the opening degree of the intake valve is made smaller than the second predetermined opening time shorter than the predetermined opening time until the opening degree becomes smaller than the predetermined opening degree, the same effect as the above is obtained. Since it is not necessary to control the fuel during the deceleration control, the deceleration control can be performed easily and reliably.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an overall configuration of an internal combustion engine to which a deceleration control method of the present invention is applied.

FIG. 2 is a sectional view of a hydraulically driven valve unit.

FIG. 3 is a characteristic diagram showing operating characteristics of an intake valve.

FIG. 4 is a flowchart showing an embodiment of the present invention.

FIG. 5 is a flowchart showing an example of the present invention.

FIG. 6 is a table diagram for determining a deceleration area.

FIG. 7 is a table diagram for determining a deceleration area.

FIG. 8 is a table diagram for determining a deceleration area.

FIG. 9 is a table diagram for determining a fuel cut area.

FIG. 10 is a graph showing a relationship between target throttle valve opening THTRG during deceleration and engine speed NE.

FIG. 11: Intake valve target valve opening angle θOFFTMG = OFF
6 is a graph showing a relationship of a difference ΔθTH between TR and a throttle valve opening and a target throttle valve opening THTRG during deceleration.

FIG. 12: Intake valve target valve opening angle θOFFTMG = OFF
6 is a graph showing the relationship between MAP and engine speed NE.

FIG. 13 is a graph showing the relationship between the correction coefficient β and the engine speed NE.

[Explanation of symbols]

2 Throttle valve 4 ECU 15 intake valve

Claims (6)

[Claims] 1. An intake valve whose valve opening period can be arbitrarily changed,
In a deceleration control method for an internal combustion engine having an electrically operated throttle valve, when a deceleration state of the engine is detected, an opening period of the intake valve is made longer than a predetermined opening period and the throttle valve is opened. Deceleration control to reduce the degree below a predetermined opening, and in the deceleration control,
An internal combustion engine, characterized in that the opening period of the intake valve is made shorter than a second predetermined opening period which is shorter than the predetermined opening time until the opening of the throttle valve becomes smaller than the predetermined opening. Deceleration control method. 2. An intake valve whose valve opening period can be arbitrarily changed,
In a deceleration control method for an internal combustion engine having an electrically operated throttle valve, when a deceleration state of the engine and a stop state of fuel supply to the engine are simultaneously detected, a predetermined valve opening period of the intake valve is set. A deceleration control is performed to make the opening of the throttle valve smaller than a predetermined opening while increasing the opening of the throttle valve, and in the deceleration control, the intake valve is opened until the opening of the throttle valve becomes smaller than the predetermined opening. A deceleration control method for an internal combustion engine, wherein a valve opening period is set shorter than a second predetermined valve opening period which is shorter than the predetermined valve opening time. 3. The predetermined opening period of the intake valve is a valve opening period in which the intake pipe internal pressure of the engine becomes equal to or lower than a predetermined pressure when the opening of the throttle valve is smaller than the predetermined opening. Item 3. A deceleration control method for an internal combustion engine according to Item 1 or 2. 4. In the deceleration control, the opening period of the intake valve is from zero to the predetermined period depending on the operating state of the engine until the opening of the throttle valve becomes smaller than the predetermined opening. 3. The deceleration control method for an internal combustion engine according to claim 1, wherein the deceleration control is performed so as to be a period between. 5. The opening period of the intake valve and the opening of the throttle valve so that the intake pressure of the engine becomes a target intake pressure when the opening of the throttle valve becomes smaller than the predetermined opening. 2. At least one of the openings of the throttle bypass valve is controlled.
Or the deceleration control method for an internal combustion engine according to item 2. 6. The deceleration state of the engine is detected by at least one of an accelerator opening degree and an accelerator opening speed, and the engine operating parameter including at least the engine speed. Deceleration control method for internal combustion engine of the above.