JPH033939A - Fuel control system - Google Patents

Abstract

PURPOSE:To improve air-fuel ratio precision by weighting and adding intake air quantities for a main throttle valve and an auxiliary throttle valve calculated via two types of filter constants with the opening effect coefficient, and calculating the actual intake air quantity. CONSTITUTION:A traction control circuit 15 determines the opening effect coefficient for the intake air detected by an air flow sensor 30 is response to the opening ratio between a main throttle valve 23 operated by an accelerator pedal and an auxiliary throttle valve 24 driven by a motor 24M and two types of filter constants corresponding to the intake pipe volume from both throttle valves 23 and 24 to an intake valve 201a. Intake air quantities for the main and auxiliary throttles 23 and 24 calculated via the two types of filter constants are weighted and added with the opening effect coefficient, and the actual intake air quantity is calculated. The basic fuel injection quantity is determined based on this actual intake air quantity, and the drive of a fuel injection valve 202 is controlled. The fuel injection quantity can be obtained with high precision.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to an MPI (multi-point injector) equipped with two throttle valves in the intake pipe and a fuel injection valve in each cylinder. Regarding fuel control methods in (injection) engines.

(Prior Art) Generally, in an MPI (Multi Point Injection) engine in which a fuel injector is provided for each cylinder, the amount of fuel injected by each injector is determined by the amount of fuel injected into the corresponding cylinder. Determined by the amount of intake air. Here, the amount of intake air in the intake pipe is
Normally, this is measured by an airflow sensor installed upstream of the throttle valve, but since there is a distance between the throttle valve and each cylinder's intake valve, and there is also a surge tank, the intake airflow obtained by the airflow sensor The amount of air is filtered taking into account the volume of the intake pipe from the throttle valve to the intake valve, and the actual amount of intake air actually taken into the cylinder is determined. Then, the basic fuel injection amount is determined by multiplying this actual intake air amount by a predetermined air-fuel ratio coefficient (+/14.7).

On the other hand, recently, a two-throttle type engine intake system has been considered in which, in addition to an accelerator direct-acting throttle valve that opens and closes in direct conjunction with the accelerator pedal, an electric throttle valve is arranged in series with the accelerator direct-acting throttle valve. This two-throttle type engine intake system controls the opening degree of the electric throttle valve mentioned above by computer, adjusts the engine output to the target value, and performs driving force control such as traction control. In the system, the intake pipe volume from the accelerator direct drive throttle valve to the intake valve is different from the intake pipe volume from the electric throttle valve to the intake valve.

(Problem to be Solved by the Invention) However, when the above-mentioned two-throttle system is adopted as an engine intake system, the actual intake pipe volume up to the intake valve depends on the opening degree of the accelerator direct drive throttle valve and the electric throttle valve. For example, if the actual intake air amount is determined by a certain filter process that takes into account the intake pipe volume for either throttle valve, it will be difficult to determine the accurate actual intake air amount. , an error occurs in the calculated value of the amount of fuel to be injected into the cylinder by the fuel injection valve.

The present invention has been developed in view of the above-mentioned problems, and makes it possible to always obtain an accurate amount of intake air and obtain a highly accurate fuel injection amount even in an MPI engine that employs a two-throttle intake system. The purpose is to provide a fuel control method.

(First stage and operation for solving the problem) That is, the fuel control system according to the present invention includes main and sub throttle valves arranged in series in the intake flow path in the intake pipe, and a fuel injection valve for each cylinder. In the installed engine, an air amount measuring means is provided in the intake passage upstream of the two throttle valves and measures the amount of air flowing into the intake passage, and detects the opening degree of each of the upper and sub throttle valves. means for determining the opening influence coefficient on the intake air amount according to the opening ratio of the above-mentioned upper and sub-throttle valve openings; Means for determining two types of filter constants according to the intake pipe volume, and intake air amounts for each of the main and sub throttle valves calculated using these two types of filter constants, weighted by the above-mentioned opening influence coefficient and added. This device includes means for obtaining an actual intake air amount, and means for determining a basic fuel injection amount based on this actual intake air amount.

(Example) Hereinafter, a case where the fuel control method of the present invention is implemented in an acceleration slip prevention device of a vehicle will be described with reference to the drawings.

FIG. 1(A) is a configuration diagram showing an acceleration slip prevention device for a vehicle. The figure shows a front-wheel drive vehicle, and WF
I? indicates the right front wheel, WPL indicates the left front wheel, WRR indicates the right rear wheel, and WRL indicates the left rear wheel. Also, 11 is the front right wheel (drive wheel) WFI? wheel speed VPI? 12 is a wheel speed sensor that detects the wheel speed VPL of the front left wheel (driving wheel) WPL; 13 is a wheel speed sensor that detects the wheel speed VRR of the rear right wheel (driven wheel) WRR; 14 is a wheel speed sensor that detects the wheel speed VRL of the rear left wheel (driven wheel) WRL. Wheel speeds VFR, VFL, VI? detected by the wheel speed sensors 11 to 14? R,VH
, C) Wakushi: Input to the 1-in controller 15.

The traction controller 15 sends a control signal to the engine 16 to perform control to prevent the drive wheels from slipping during acceleration.

FIG. 1(B) shows the intake system in the engine 16, in which 21 is an air cleaner;
2 is an intake pipe, 22a is a surge tank, and the intake pipe 22
In addition to the main throttle valve THI 1123 whose opening degree θm is operated by the accelerator pedal, a sub-throttle valve THs 24 whose opening degree θS is controlled by a control signal from the traction controller 15 is provided. That is, the intake air introduced into the intake pipe 22 via the air cleaner 21 is taken from the surge tank 22a to the intake valve 201a side via the sub-throttle valve THs24 and the main throttle valve THa+23 in series. The opening degree θS of the valve THs 24 is controlled by a control signal from the transmission controller 15 via the motor drive circuit 25 and its motor 24N1, and the amount of intake air to the engine is adjusted.

Here, the opening degrees θ and θS of the main throttle valve THm23 and the sub-throttle valve THs 24 are detected by a main throttle position sensor (TPSI) 26 and a sub-throttle position sensor (TPS2) 27, respectively. In addition, the main throttle valve THm23 has a main throttle idle 5W28 that detects the non-depressed state of the accelerator pedal, that is, the idling state of the engine, and the subthrottle valve THs24 has a subthrottle full open SW29.
are provided respectively.

Further, downstream of the air cleaner 21, an intake pipe 22 is provided.
An air flow sensor (AFS) 30 is provided to detect the amount of air flowing into the surge tank 22a, and the surge tank 22a is provided with a fuel mixture that is sucked into the in-cylinder combustion chamber (cylinder) 204 from the intake valve 201a. A negative pressure sensor 30a is provided to detect the negative pressure in the pipe (boost pressure) when the pipe is turned on.

Each of these sensors 26, 27, 30, 30a and 5W28
The output signals from .degree. 29 are all given to the traction controller 15.

On the other hand, a fuel injection valve (fuel pump injector) 202 is provided in the intake pipe 22 at a position immediately before the intake valve 201a that communicates with the in-cylinder combustion chamber 204. This fuel injection valve 20
2 is an engine in which fuel is injected under the control of the traction controller 15 during the intake stroke in which the piston 203 moves downward with the opening operation of the intake valve 201a, and the fuel injected from the fuel injection valve 202 in this engine intake stroke is Opening degree θm of two throttle valves 23 and 24,
The mixture is mixed with the intake air according to θS to form a mixture and is intake into the combustion chamber 204.

Here, the basic fuel injection fflF o with respect to the intake air amount Go into the combustion chamber 204 is the ideal air-fuel ratio [A(, Al
r) 7F (Fuel) = 14, determined based on 71, so the actual intake air ff1G. By accurately determining the basic fuel amount Fo to be injected into the fuel injection valve 201a, the basic fuel amount Fo can be controlled with high precision.

First, the amount of air G1 flowing into the intake pipe 22 is measured by the air flow sensor 30, but the actual intake air m G
o is obtained by processing the inflow air amount GI using a delay time constant α1 or G2 (hereinafter referred to as a filter constant) depending on the intake pipe volume V or V+ΔV from each throttle valve 23, 24 to the intake valve 201a.

αI separation υ−η/(V+υeη) G2−υφη/(V+Δ■10−η) However, υ is the volume of the combustion chamber 204, and η is the volumetric efficiency.

In other words, when the sub-throttle valve THs 24 is fully open, the intake air, S!
The intake air ff1G when the adjustment is achieved is determined by the following formula (A1) based on the filter constant α1.

G1-α+GI+(1-G1)G, 0...(AI)
However, GIO is the intake air ff1G1 calculated in the previous detection cycle.

In addition, when the main throttle valve THm23 is fully open and the intake air is adjusted only by the opening degree θS of the sub throttle valve THs24, the intake air mG2 is calculated by the following formula (A2) based on the filter constant α2. .

G2-G2 c++ (1-722) G20 -(
A2) However, G20 is the intake air amount 62 calculated in the previous detection cycle.

Therefore, the actual intake air amount Go when the intake air is adjusted by the throttle openings θm and θS of the main throttle valve THQ123 and the sub-throttle valve THs24 is the intake air amount Go assuming that the sub-throttle valve THs2'4 is fully open. Air ink G 1, main throttle, valve THI12
The following formula (A3) is obtained by weighting and adding the intake air Hk G 2 assuming a fully open state of 3 by the opening influence coefficient β corresponding to the opening ratio of each throttle opening θ■ and θS.
It is determined by

Go-βG, + (1-β) G2 - (A3)
Here, the opening degree influence coefficient β-f (θm, θS) according to the opening ratio between the opening degree θl of the main throttle valve THm23 and the opening degree θS of the sub-throttle valve THs24 is calculated as follows: β-1 when fully open, main throttle opening θI
When is fully open, β-0, and when main throttle opening θl and sub-throttle opening θS are equal, β-0.5, and β is determined using θ■ and θS as parameters. It is determined based on the three-dimensional map (see Figure 31).

On the other hand, in FIG. 1(A), 17 is the front right wheel WP.
A wheel cylinder 18 performs braking on the front left wheel WFL. Normally, these wheel cylinders are connected to mask cylinders (not shown) by operating a brake pedal (not shown).
Pressure oil is supplied via. When traction control is activated, pressure oil can be supplied from another route as described below. Hydraulic pressure source 19 to the wheel cylinder 17
Pressure oil is supplied from the wheel cylinder 17 through the inlet valve 17i, and pressure oil is discharged from the wheel cylinder 17 to the reservoir 20 through the outlet valve 170. Further, pressure oil is supplied from the hydraulic source 19 to the wheel cylinder 18 through an inlet valve 18t, and pressure oil is discharged from the wheel cylinder 18 to the reservoir 20 through an outlet valve 18o. Opening/closing control of the inlet valves 17i and 181 and the outlet valves 17o and 18o is performed by the traction controller 15.

Here, the driving force control of the engine 16 and the driving wheel WF are performed.
Slip prevention control by braking control of R and WPL is started when the slip amount of drive wheels WFR and WFL exceeds a predetermined slip judgment value α, and when the slip amount becomes below a predetermined slip judgment value α. It will be terminated when

Furthermore, in FIG. 1(A), 81a to 81d are fuel injection injectors, and the injectors 81a to 81d are fuel injection injectors.
1d, that is, the fuel injection amount, is determined by the air flow sensor (AF) in the traction controller 15 or engine control unit (ECU) 82.
S) is set according to the intake air amount based on the signal from 30. Further, 83 is an engine rotation sensor that detects the rotation of the crankshaft of the engine 16, and 84 is an engine torque sensor that detects the output torque of the engine 16, and the engine rotation detection signal and engine torque detected by each sensor 8B and 84 are The detection signal is output to the ECU 32 mentioned above. Note that the traction controller 15 is an EC
It may be integrated with U32.

Next, the configuration of the traction controller 15 will be described with reference to FIG. 2.

In the figure, 11.12 is a wheel speed sensor that detects the wheel speeds VFR, VPL of the driving wheels WPR, WFL, and the driving wheel speeds VFR, VFL detected by this wheel speed sensor 1'1.12 are The high vehicle speed selection section 31 and the averaging section 32 are also sent. The high vehicle speed selector 31 selects the higher wheel speed of the drive wheel speeds VFR and VPL, and the drive wheel speed selected by the high vehicle speed selector 31 is outputted to a weighted section 33. Ru. Further, the averaging section 32 calculates the average driving wheel speed (V
FR+VPL)/2, and this average part 32
The average drive wheel speed calculated by is outputted to the weighted section 34. The weighting section 33 is the high vehicle speed selection section 31
Drive wheel WPR selected and output by.

Multiply the wheel speed of the higher WPL by KG (variable),
Further, the weighting section 34 multiplies (variable) the average driving wheel speed outputted by the averaging section 32 by (1-KG), and each of the above-mentioned modeling is performed by weighting the driving wheel speed weighted by the sections 33 and 34. The wheel speed and the average driving wheel speed are supplied to the adding section 35 and added, and the driving wheel speed VF is calculated.

Here, the variable KG is a variable that changes according to the centripetal acceleration GY, as shown in FIG.
is a predetermined value (for example, 0.1g-1, where g is gravitational acceleration)
It is set so that it is proportional to the magnitude of the value up to and becomes "1" above that value.

On the other hand, the driven wheel speeds VRR and VRL detected by the wheel speed sensors 13 and 14 are both sent to a low vehicle speed selection section 36 and a high vehicle speed selection section 37. The low vehicle speed selection section 36 selects the driven wheel speed VI? The low wheel speed side is selected from R and VRL, and the high vehicle speed selection section 37 selects the high wheel speed side from among the driven wheel speeds VRR and VRL. The low driven wheel speed selected by section 36 is weighted and output to section 38, and the high driven wheel speed selected by high vehicle speed selection section 37 is weighted and output to section 39.

The weighting unit 38 indicates the driven wheel W)? which is selected and output by the low vehicle speed selection unit 36. I? , WI? The lower wheel speed of L is multiplied by Kr (variable), and the weighting is
is the driven wheel Wl? selected and output by the high vehicle speed selection section 37? I? , WRL, whichever is higher, is the wheel speed (1
-Kr) times (variables), each of the above molds is part 38
The driven wheel speed weighted by
0 and is added to calculate the driven wheel speed VR. The driven wheel speed VR calculated by this addition section 40 is output to a multiplication section 40'. This multiplier 40' multiplies the calculated driven wheel speed VR by (1+α), and through this multiplier 40', the driven wheel speeds VRR, VRI,
A target driving wheel speed Vφ is calculated based on.

Here, the variable K" is a variable that changes between "1" and "0" according to the centripetal acceleration GY, as shown in FIG.

Then, the driving wheel speed V calculated by the adding section 35
F and the target driving wheel speed Vφ calculated by the multiplication section 40' are given to the subtraction section 41.

This subtraction unit 41 subtracts the target driving wheel speed Vφ from the driving wheel speed VF, and calculates the slip f of the driving wheels WPR, WFL.
It calculates f1DVi (-VF-Vφ),
The slip ffi D calculated by this subtraction unit 41
V i ' is given to the adder 42. This addition section 4
2 is the slip amount DV i′ expressed as the centripetal acceleration GY
The slip correction mVg (see FIG. 5), which changes according to the centripetal acceleration GY, is given from the slip amount correction section 43, and is corrected according to the rate of change ΔGY of the centripetal acceleration GY. Changing slip correction f
f1Vd (sixth reference) is given from the slip amount correction section 44. That is, the addition section 42 adds each slip correction amount Vg to the slip RDVi' obtained from the subtraction section.
The slip Q D V i corrected according to the centripetal acceleration GY and its rate of change ΔGY is added to the TSn calculation unit 45 and TPn calculation unit 4
Sent to 6.

The calculation unit 45a in the TSn calculation unit 45 calculates an integral correction torque TSn′ (−ΣKl·DVi) obtained by multiplying the slip 1DVi by a coefficient Kl and integrating the result.
This integral type correction torque "rsn' is sent to the coefficient multiplier 45b. In other words, the integral type correction torque TSn'
Is the drive wheel WFI? , is a correction value for the drive torque of WPL, and is the drive wheel w pR.

It is necessary to adjust the control gain according to changes in the speed change characteristics of the power transmission mechanism existing between the WFL and the engine 16.
The integral correction torque TSn' obtained from a is multiplied by a coefficient GKi that differs depending on the gear position to calculate the integral correction torque TSn corresponding to the gear position. Here, the above variable K
l is a coefficient that changes depending on the slip amount DVi.

On the other hand, the calculation unit 46a in the TPnm nose section 46 calculates the proportional correction torque TPn' (=DV1-Kp) by multiplying the slip 1DVi by the coefficient Kp. Section 46
sent to b. In other words, this proportional correction torque TPn
Similarly to the above integral correction torque TSn', the driving wheel W
A correction value for the drive torque of the FR and WFL, and the control gain thereof needs to be adjusted in accordance with changes in the speed change characteristics of the power transmission mechanism that exists between the drive wheels WFR and WPL and the engine 16. Then, the coefficient multiplier 46b calculates the proportional correction torque T obtained from the arithmetic unit 46a.
Multiply Sn' by a coefficient GKp that differs depending on the gear position,
A proportional correction torque TPn corresponding to the gear position is calculated.

On the other hand, the driven wheel speed VR obtained by the addition section 40 is sent to the reference torque calculation section 47 as the vehicle body speed VB. The reference torque calculation section 47 first calculates the acceleration GB of the vehicle speed VB in a vehicle acceleration calculation section 47a.The vehicle acceleration GB obtained by the vehicle acceleration calculation section 47a is passed through a filter 47b to the vehicle acceleration GB.
It is sent as F to the reference torque calculation unit 47c. This reference torque calculation unit 47c calculates the reference torque TG(-
GBPXWXRe), and this reference torque TO becomes the torque value that the engine 16 should originally output when accelerating at the vehicle body acceleration GBF.

The filter 47b determines, for example, in three stages how far in time the reference torque TG calculated by the reference torque calculating section 47c is calculated based on the vehicle body acceleration GB. The vehicle body acceleration GBP is the vehicle body acceleration GBn detected this time and the vehicle body acceleration G which is the output of the filter 47b up to the previous time.
BPn-1 is calculated according to the current slip ratio S and acceleration state.

For example, if the current acceleration of the vehicle is increasing and its slip ratio S is in the state shown in range "1j" in Fig. 15, it will quickly shift to the state in range "2" in response to the increase in acceleration. In order to
The latest vehicle acceleration GB is calculated by averaging the values with the same weighting as
Fn is calculated by the following formula (1).

GBFn-(GBn+GBFn-1)/2
-(1) Also, for example, if the current acceleration of the vehicle is decreasing and the slip ratio S is S>Sl and shifts from the range "2" to "3" shown in Fig. 15, it is possible to In order to maintain control according to the state in range "2" as much as possible, the vehicle body acceleration GBF is determined by the previous output G B of the filter 47b.
Weight is placed on Fn-1, and the vehicle acceleration GBPn is calculated using the following formula (2) as having a value closer to the previously calculated vehicle body acceleration GBFn-1 compared to when calculating using the above formula (1). .

GBFn=(GBn+7GBFn-1)/8-(2
) Furthermore, for example, when the acceleration of the vehicle is currently decreasing, the slip rate S is within the range r shown in FIG. 15 at SOS 1.
2J -rlJ, in order to further increase the degree of maintenance of control according to the state in the range "2" as much as possible, the vehicle body acceleration GBF is changed from the previous output GBFn-1 of the filter 47b. Further weight is placed on , and the above formula (2)
The previously calculated vehicle body acceleration G BP
The vehicle body acceleration GBPn having a value close to n-1 is calculated by the following equation (3).

GBPn = (GBn+15GBPn-1) /16
-(3) Next, the reference torque TG calculated by the reference torque calculation section 47 is output to the subtraction section 48.

This subtraction section 48 subtracts the integral correction torque TSn calculated by the TSn calculation section 45 from the reference torque TG obtained from the reference torque calculation section 47, and the subtraction data is further sent to the subtraction section 49. It will be done. This subtraction unit 49 further subtracts the proportional correction torque TPn calculated by the TPn calculation unit 46 from the subtraction data obtained from the subtraction unit 48, and the subtraction data drives the drive wheels WPR, WFL. Target torque Tφ of the axle torque to be
It is sent to the engine torque calculation unit 50 via switch S1. In other words, the target torque Tφ has a value according to the following equation (4).

T?

The target torque Tφ for the WFL is divided by the total gear ratio between the engine 16 and the drive wheel axle to convert it into a target engine torque Te.
is sent to the lower limit setting section 501. This lower limit value setting section 5
01 is the lower limit value of the target engine torque Te calculated by the engine torque output section 50, as shown in FIGS. 16 and 17, depending on the elapsed time t from the start of traction control or the vehicle speed VB. The lower limit value setting section 5017 sends the target engine torque Tel, whose lower limit value is limited, to the target air amount calculation section 502. This target air amount calculation unit 502 calculates a target air amount ((
This target air amount A/N m is calculated based on the engine rotational speed Ne and the above-mentioned "1 standard engine torque Tel", with reference to a three-dimensional map as shown in Fig. 20. is required.

A/NI! -f [Ne, Te1l, where the above A
/ N ra is the amount of intake air per 21 rotations of the edge (
mass), and f[Ne, Tel] is a three-dimensional map with engine rotational speed Ne and target engine torque Tel as parameters.

Note that the target air amount (quality ff1) A/Nm is determined by a coefficient K as shown in FIG. 21 with respect to the engine rotation speed Ne.
It may be obtained by multiplying a by the target engine torque Tel as shown in the following formula.

A/Nta - Ka (Ne) * TelThen, the target air amount calculation unit 502 calculates the above intake air amount (
The mass) A/NTI+ is corrected according to the intake air temperature and atmospheric pressure, and converted to the intake air amount (volume) A/NV under standard atmospheric conditions.

A/Nv = (A/Nm)/fKt(AT)
* Kp (8P) 1 Here, A / N v is the amount of intake air (volume) per 21 rotations of the edge, Kt is the density correction coefficient using the intake air temperature (AT) as a parameter (see Figure 22), and Kp is the large This is a density correction coefficient (see FIG. 23) using atmospheric pressure (AP) as a parameter.

In this way, the target intake air amount (volume) A/NV obtained by the target air amount calculation section 502 is determined by the target air amount correction section 503.
sent to. The target air amount correction unit 503 corrects the target intake air ff1A/Nv (volume) calculated by the target air amount calculation unit 502 according to the intake air temperature using the following formula,
Find the target air amount A/N.

A/NO-A/Nv Zero Ka' (AT) Here,
A/No is the target air amount after correction, A/Nv is the target air amount before correction, and Ka' is a correction coefficient based on the intake air temperature (8T) (see FIG. 24).

Next, the target air amount A/No corrected and output by the target air amount correction section 503 is sent to the equivalent target throttle opening calculation section 504. This equivalent target throttle opening calculation unit 504 calculates the engine rotational speed Ne and the target air amount A/
The equivalent target throttle opening θ0 is determined based on the number and the map shown in FIG. 25, and this equivalent target throttle opening θ0. is the target throttle opening calculation unit 5
Sent to 05.

Here, the equivalent target throttle opening degree θ0 is the throttle valve opening degree for achieving the target air amount A/No when the number of throttle valves in the intake pipe 22 is one.

Then, the target throttle opening calculation unit 505 determines the target for the sub throttle valve THs24 by referring to a map as shown in FIG. 30 based on the equivalent target throttle opening θ0 and the throttle opening θ1 of the main throttle valve THm23. Find the sub-throttle opening θS'.

On the other hand, the target air amount A/No corrected and output by the target air amount correction section 53 is also sent to the subtraction section 506. This subtraction unit 506 calculates the actual intake air ff1 per rotation of the edge 21 detected at each predetermined sampling time based on the target air amount A/No and the air flow sensor 30.
The difference ΔA/N between the target air ff1A/N and the actual air EIA/N is calculated, and the deviation ΔA/N between the target air ff1A/No and the actual air EIA/N is sent to the PID control unit 507. This PID control section 50
7 calculates the opening correction amount Δθ of the sub-throttle valve THs 24 corresponding to the air amount deviation ΔA/N, and this sub-throttle opening correction amount Δθ is sent to the addition section 508.

Here, the sub-throttle opening correction amount Δθ obtained by the PID control section 507 is the opening correction amount Δθ obtained by the proportional control.
This is the sum of the opening correction amount Δθ1 based on θp1 integral control and the opening correction amount Δθd based on differential control.

Δθ−Δθp+Δθ1+Δθd Δθp=Kp(Ne) zero Kth(Ne)* ΔA/
NΔθ1−Ki(Ne)* Kth (Ne)*Σ(Δ
A/l1l)Δθd−Kd(Ne)*Kth(Ne
)$1ΔAbarΔA/No1dl where each coefficient Kp,
Ki and Kd are the proportional gain (see Fig. 26), integral gain (see Fig. 27), and differential gain (see Fig. 28), respectively, with the engine rotation speed Ne as a parameter, and Kth is the engine rotation speed Ne as a parameter. Δ as a parameter
A/N-Δθ conversion gain (see Figure 29), ΔA/N is the deviation between the target air amount A/No and the actual air amount A/N, Δ
A/No1d is Δ at the previous sampling timing
This is A/N.

Then, the adding unit 508 adds the target sub-throttle opening θS' calculated by the target throttle opening calculation unit 505 and the sub-throttle opening correction amount Δθ calculated by the PID control unit 507, and performs feedback correction. The target sub-throttle opening degree θsO is calculated. This target sub-throttle opening θSO is sent to the motor drive circuit 25 as a sub-throttle valve opening signal, and the sub-throttle valve THs 2
The opening degree θS of No. 4 is controlled.

On the other hand, the driven wheel WRI detected by the wheel speed sensors 13 and 14? , WRL wheel speeds VRR and VRL are sent to the centripetal acceleration calculation section 53. The centripetal acceleration calculation section 53 calculates the centripetal acceleration GY' for determining the turning degree of the vehicle, and this centripetal acceleration GY' is sent to the centripetal acceleration correction section 54.

The centripetal acceleration correction section 54 corrects the centripetal acceleration GY' according to the vehicle speed to obtain the centripetal acceleration GY.

GY-Kv .GY' Here, Kv is a coefficient that changes depending on the vehicle speed, as shown in FIGS. 7 to 12.

By the way, the higher driven wheel speed output from the high vehicle speed selection section 37 is sent to the subtraction section 55, and the speed of the right driven wheel W
It is subtracted from the PR wheel speed VFR.

Further, the wheel speed of the larger driven wheel outputted from the high vehicle speed selection section 37 is sent to the subtraction section 56, and the wheel speed of the left driving wheel WPL is
is subtracted from the wheel speed VFL. Then, the subtraction section 55
The subtraction output by
6 is sent to the multiplier 58. The multiplication section 57 multiplies the subtraction output from the subtraction section 55 by KB (o<KB
<1) L, . . . Also, the multiplication section 58 multiplies the subtraction output from the subtraction section 56 by (1-KB), and each of these multiplication outputs is sent to the addition section 59 and added to the right drive wheel WF.
The slip ff1DVFR of R is determined.

On the other hand, the subtraction output from the subtraction section 56 is sent to the multiplication section 60, and the subtraction output from the subtraction section 55 is sent to the multiplication section 61. The multiplication section 60 converts the subtraction output from the subtraction section 56 into K
B times (0<KB<1)L, and the multiplier 61 multiplies the subtraction output from the subtraction unit 55 by (1-KB), and the respective multiplication outputs are sent to the addition unit 62 and added. The slip amount DVFL of the left drive wheel WFL is determined.

Here, the above KB is a variable that changes according to the elapsed time t from the start of traction control, as shown in FIG. 13. In this case, when traction control starts, KB-rO,5J, As the control progresses, it is set to approach KB-rO, 8J. In other words, if the brake control of the left and right drive wheels WPR and WFL is completely independent, when only one drive wheel is braked and its rotation is reduced, the opposite drive wheel will slip due to the action of the differential gear. Therefore, the brake is applied, and the structure is designed to prevent this operation from being repeated.

Next, the slip fiDVPR of the right drive wheel WPR obtained by the adding section 59 is sent to the differentiating section 63.

Further, the slip amount DVFL of the left driving wheel WPL obtained by the adding section 62 is sent to the differentiating section 64.

The differentiating sections 63 and 64 differentiate the slip amounts DVFR and DVPL of the corresponding drive wheels to obtain their temporal changes, that is, the slip accelerations GPR and GPL, and the right drive wheel WFI? Slip acceleration IfiGFR
is sent to the brake fluid pressure change ji (ΔP) calculation unit 65, and
The slip acceleration GFL of the left drive wheel WFL is sent to the brake fluid pressure change amount (ΔP) calculation unit 66. The brake fluid pressure change amount (ΔP) calculation unit 65, 66 calculates the amount of change in brake fluid pressure based on the GFR (GPL)ΔP conversion map as shown in FIG.
Slip acceleration GFI of each drive wheel WFR, WFL? ,G
The brake fluid pressure change amount ΔP for suppressing FL is determined by the brake fluid pressure change amount ΔP for the left and right drive wheels WFR, WFL, respectively, by the ΔP-T converter 67.68.
sent to.

This ΔP-T converter 67, 68 converts the brake fluid pressure change amount ΔP of each corresponding drive wheel into the opening time T of the inlet valves 17i, 18i and the outlet valves 17o, 18o in FIG. 1(A). The above ΔP
When is positive, the inlet valve 17 for the right driving wheel WFR is
i, and also controls the inlet valve 18i for the left driving wheel WPL to open according to the opening time T obtained by the ΔP-T converter 68. Moreover, when the above ΔP is negative,
The opening of the outlet valve 17o for the right driving wheel WFR is controlled according to the opening time T obtained by the ΔP-T conversion section 67, and the opening of the outlet valve 17o for the right driving wheel WFR is controlled according to the opening time T obtained by the ΔP-T conversion section 68. Controls the opening of the outlet valve 18o.

In addition, the GPI? shown in FIG. 14 above? (GPL)-
The conversion value based on the broken line a in the ΔP conversion map is for strengthening the brake control for the inner drive wheel when performing brake control during a turn.

On the other hand, a switch Sl is interposed between the subtraction section 49 where the target torque Tφ is calculated and the engine torque calculation section 50, and a brake fluid pressure change amount (ΔP) calculation section 65
．． Switches 32a are provided between the ΔP-T conversion units 67 and 66 and 68, respectively.

S2b is intervened. Each of the above switches Sl.

S2a and S2b are closed/opened when slip control start/end conditions, which will be described later, are satisfied, respectively.
The switches Sl, 52a, and S2b are all controlled to open and close by a control start/end determination section 69. A slip determination signal from a slip determination section 70 is given to this control start/end determination section 69 . This slip determination section 70 calculates a slip amount DV obtained through a subtraction section 41 and an addition section 42 based on the driving wheel speed VF and the driven wheel speed VR.
+ exceeds the slip judgment value α stored in advance in the slip judgment value storage section 71, and this slip judgment signal is given to the control start/end judgment section 69.

Here, the six control start/end determination units output a control start signal when the slip determination signal (D Vi>α) is input from the slip determination unit 70, and
S2a and S2b are closed.

In addition, the six control start/end determination sections include a slip determination section 7.
When the non-slip determination signal (DVi≦α) is input from 0 to 0, a control end signal is output, and switches Sl, S2a, S
2b is opened.

Next, the operation of the acceleration slip prevention device for a vehicle according to an embodiment of the present invention configured as described above will be explained.

In Figures 1 and 2, wheel speed sensors 13.14
The wheel speed of the driven wheel (rear wheel) output from the high vehicle speed selection section 36. Low vehicle speed selection section 37. It is input to the centripetal acceleration calculation section 53. The low vehicle speed selection section 36 selects the smaller wheel speed of the left and right driven wheels, and the high vehicle speed selection section 37 selects the larger wheel speed of the left and right driven wheels. During normal straight running, if the wheel speeds of the left and right driven wheels are the same, the same wheel speed is selected from the low vehicle speed selection section 36 and the high vehicle speed selection section 37. In addition, the wheel speeds of the left and right driven wheels are input to the centripetal acceleration calculation unit 53, and the turning angle when the vehicle is turning, that is, how steep the turn is, is determined from the wheel speeds of the left and right driven wheels. The degree to which the

Hereinafter, how the centripetal acceleration is calculated in the centripetal acceleration calculating section 53 will be explained.

In a front-wheel drive vehicle, since the rear wheels are driven wheels, the vehicle speed at that position can be detected by the wheel speed sensor regardless of slip caused by the drive, so Ackermann geometry can be used. In other words, in a steady turn, the centripetal acceleration GY' is GY' -v2/r
-(5) (V-vehicle speed, r-turning radius).

For example, when the vehicle is turning to the right as shown in FIG. 19, the center of turning is MO, and the center of turning is
When the distance from to the inner wheel side (WRR) is rl, the tread is Δ'', the wheel speed of the inner wheel side (WRR) is Vl, and the wheel speed of the outer wheel side (W , V2 /Vl −(Δr+rl)/rl...(
6).

Then, by transforming the above equation (6), 1/ rl = (v2-vl)/Δr-v 1 =
473. Then, the claimed center acceleration GY' characterized by the inner ring side is GY' -vl 2/ rl -vl 2 ・(v2-vl)/Δr-v1=vl
It is calculated as (v2-vl)/Δr (8).

That is, the centripetal acceleration GY' is calculated using equation (8). By the way, when turning, the inner wheel speed v1 is smaller than the outer wheel speed v2, so the inner wheel speed v
1 is used to calculate the centripetal acceleration GY', the centripetal acceleration GY' is calculated to be smaller than the actual value. Therefore, the coefficient KG multiplied in the weighting section 33 is the centripetal acceleration GY'
is estimated to be small because it is estimated to be small. Therefore, since the driving wheel speed VF is estimated to be small, the slip amount DVi' (VP-Vφ) is also estimated to be small. As a result, since the target torque Tφ is estimated to be large, the target engine torque is also estimated to be large, thereby providing sufficient driving force even when turning.

By the way, at very low speeds, the distance from the inner wheel side to the center of turning MO is 1, as shown in Figure 19, but in a vehicle that understeers as the speed increases, the center of turning is M. , and the distance is r(r>r
l).

Even when the speed increases in this way, since the turning radius is calculated using rl, the centripetal acceleration GY' calculated based on the above equation (8) is calculated as a larger value than the actual value. Therefore, the centripetal acceleration GY′ calculated in the centripetal acceleration calculation unit 53 is
The centripetal acceleration GY' is multiplied by the coefficient Kv in FIG. 7 so that the centripetal acceleration GY becomes smaller at high speeds. This variable Kv is set to decrease according to the vehicle speed, and may be set as shown in FIG. 8 or 9. In this way, the centripetal acceleration correction unit 54 outputs the corrected centripetal acceleration GY.

On the other hand, as the speed increases, oversteer occurs (r<
rl) In the vehicle, the centripetal acceleration correction unit 54 performs a correction that is completely opposite to that of the understeering vehicle described above. That is, one of the variables Kv shown in FIGS. 10 to 12 is used to correct the centripetal acceleration GY' calculated by the centripetal acceleration calculating section 53 so that it increases as the vehicle speed increases.

By the way, the smaller wheel speed selected in the low vehicle speed selection section 36 is multiplied by the variable Kr in the weighting section 38 as shown in FIG. 4, and the high vehicle speed selected in the high vehicle speed selection section 37 is not weighted. In part 39, the variable (1-Kr
) will be multiplied. The variable Kr is the centripetal acceleration GY of 0.9, for example.
It is set to "1" when the turning becomes larger than g, and becomes "0" when the centripetal acceleration GY becomes smaller than 0.4 g.
is set to

Therefore, for a turn where the centripetal acceleration GY is greater than 0.9 g, the wheel speed of the lower vehicle speed among the driven wheels output from the low vehicle speed selection section 36, that is, the wheel speed of the inner wheel at the time of selection is selected. be done.

Then, the weighting is performed by adding the wheel speeds output from sections 38 and 39 in an adding section 40 to obtain the driven wheel speed VR.
Further, the driven wheel speed VR is multiplied by (1+α) in a multiplier 40' to obtain the target driving wheel speed Vφ.

Further, after the higher wheel speed of the drive wheels is selected in the high vehicle speed selection section 31, weighting is performed in the section 33.
In this case, the variable KG is multiplied as shown in FIG. Furthermore, the average vehicle speed (V
FR+VPL)/2 is weighted in section 34,
(1-KG), and the above-mentioned weighting is added to the output of the section 33 and the adding section 35 to obtain the driving wheel speed VF. Therefore, when the centripetal acceleration GY becomes, for example, 0.1 g or more,
KG-1, the wheel speed of the larger of the two drive wheels output from the high vehicle speed selection section 31 is output. In other words, when the turning angle of the vehicle increases and the centripetal acceleration GY becomes, for example, 0.9 g or more,
In order to obtain rKG-Kr-IJ, on the driving wheel side, the wheel speed of the outer wheel side with a higher wheel speed is set as the driving wheel speed VF, and on the driven wheel side, the wheel speed of the inner wheel side with a lower wheel speed is set as the driven wheel speed VR. Therefore, the slip amount DVi (=VF-Vφ) calculated by the subtraction unit 41 is estimated to be large. Therefore, in order to estimate the target torque Tφ to be small, the engine output is reduced, the slip ratio S is reduced, and the lateral force A can be increased as shown in FIG. can be raised to make a safe turn.

The above slip ff1DVi' is the slip amount correction section 43
, a slip correction amount Vg as shown in FIG. 5 is added only when turning when centripetal acceleration GY occurs, and
In the slip amount correction section 44, slip Ia V d as shown in FIG. 6 is added.

For example, if we assume a force that bends at a right angle,
In the first half of the turn, the centripetal acceleration GY and its rate of change over time ΔGY take positive values, but in the second half of the curve, the rate of change over time ΔGY of the centripetal acceleration GY takes a negative value.

Therefore, in the first half of the curve, in the adding section 42,
The slip correction Q shown in FIG. 5 is applied to the slip money DV i'.
Vg (〉0) and slip correction 1Vd (〉
0) is added to obtain slip ff1DVt, and in the latter half of the curve, slip correction amount Vg (>0) and slip correction amount Vd (<0) are added to obtain slip fit.
D Vi. Therefore, the slip amount DVi in the second half of the turn is the slip amount DVi in the first half of the turn.
By estimating the force to be smaller than that, the engine output is reduced in the first half of the turn to increase lateral force, and in the second half of the turn, the engine output is restored compared to the first half to improve the acceleration of the vehicle. .

In this way, the corrected slip Jet D V
i is sent to the TSnS calculator 45 with a sampling time T of, for example, 15m5. In this TSn/1lIt calculator 45, the slip, 1DVi, is multiplied by a coefficient Kl and integrated to obtain the corrected torque TSn.

That is, the correction torque obtained by integrating the slip 1DVi, that is, the integral type correction torque TSn is obtained as TSn - GKI - Σ (Kl - DVi) (Kl is a coefficient that changes depending on the slip amount DVI).

Further, the slip m D V I is sent to the T P n calculation unit 46 at every sampling time T, and the correction torque T
Pn is calculated. That is, the correction torque proportional to the lip m D Vi , that is, the proportional correction torque TPn is obtained as TPn - GKp - DVi - Kp (Kp is a coefficient).

Furthermore, the values of the coefficients GKi and GKp used in the calculations in the coefficient multipliers 45b and 46b are switched to values corresponding to the gear position after the shift after a set time from the start of the shift during upshifting. This is because it takes time from the start of the shift until the gear is actually changed and the shift is completed, and when the above-mentioned coefficients GKi and GKp corresponding to the high gear after the shift are used at the time of the shift up, the above-mentioned correction torque TS
Since the values of n and TPn correspond to the above-mentioned high speed gear, they become smaller than the values before the start of the shift even though the actual shift has not finished, and the target torque Tφ becomes large, inducing slip and causing control. This is because it becomes unstable.

Further, the driven wheel speed VR output from the addition section 40 is inputted to the reference torque calculation section 47 as the vehicle body speed VB. Then, the vehicle body acceleration calculating section 47a calculates the acceleration GB of the vehicle body speed VB. Then, the acceleration G of the vehicle body speed calculated in the vehicle body acceleration calculation section 47a
As explained in the configuration section, B is filtered by the filter 47b according to any one of equations -(1) to (3), so that GBP is set to an optimal value depending on the state of acceleration GB. There is. Then, the reference torque calculation section 47c
, the reference torque TG (-GBFXW X R
e) is calculated.

The reference torque TG and the integral correction torque T
Subtraction with Sn is performed in a subtraction unit 48, and the proportional correction torque TPn is further subtracted in a subtraction unit 49. In this way, the target torque Tφ is calculated as Tφ - TG - TSn - TPn.

This target torque Tφ, that is, the axle torque Tφ is given to the engine torque calculation unit 50 via the switch S1,
It is converted into target engine torque Te. The lower limit value of this target engine torque Te is limited by a lower limit value setting section 501 that sets a lower limit value Tl1m of engine torque. Then, the target engine torque Tel with the lower limit value is sent to the target air amount calculation section 502 and the target engine torque Te1 is sent to the target air amount calculation section 502.
A target air amount (mass) A/Nn+ for outputting l is calculated. In addition, the target air amount calculation unit 502 corrects the intake air jlA/NII (quality m) based on the intake air temperature and atmospheric pressure, and calculates the intake air amount A/N under the standard atmospheric pressure state.
It is converted to v (volume).

Target intake air amount A/Nv calculated in this way
(Volume) is corrected by the intake air temperature in the target air amount correction unit 503, and is set as the target air amount A/No.

Then, the target air ji A/N o output from the target air amount correction section 503 is sent to the equivalent target throttle opening calculation section 504, and the map in FIG. 25 is referred to to calculate the engine rotation speed Ne and the target air amount. An equivalent target throttle opening θ0 for A/No is determined.

This equivalent target throttle opening θ0 is sent to the target throttle opening calculation unit 505, and the map in FIG. The target throttle opening θS' for the target throttle opening θS' is calculated.

On the other hand, the target air amount A/No corrected and outputted from the target air amount correction section 503 is sent to a subtraction section 506, and the current air amount A/N detected by the air flow sensor 30 at every predetermined sampling time is sent to the subtraction section 506. The difference ΔA/N is calculated. This ΔA/N is sent to the PID control unit 507 and the PID
Control is performed, and the opening correction amount Δθ corresponding to the ΔA/N is
is calculated. This opening correction amount Δθ is added to the target sub-throttle opening θS' in an adding section 508, and a feedback-corrected target sub-throttle opening θSO is calculated.

Target sub-throttle opening θS obtained as above
O is sent to the motor drive circuits 2 and 5 as a sub-throttle valve opening signal, and the opening θS of the sub-throttle valve THs 24 is controlled.

In this way, when the opening degree θ1 of the main throttle valve THm23 and the opening degree θS of the sub-throttle valve THs24 are set,
Outside air is introduced into the intake pipe 22 according to the throttle opening degree θ-1θs, and fuel injection control is executed according to the intake air amount.

FIG. 32 shows the basic fuel injection amount F based on the fuel control method of the present invention. This is a flowchart showing the decision operation of
The inflow air i1G+ to the intake pipe 22 measured by the air flow sensor 30 is determined by the traction control
(step Sl). In addition, the main throttle opening θm1 of the main throttle valve THm23 corresponding to the accelerator pedal operation is measured by the main throttle position sensor (TPSI) 26, and the sub throttle valve T is measured by the sub throttle position sensor (TPS2) 27.
The sub-throttle opening degree θS corresponding to the motor drive control of Hs 24 is inputted to the traction controller 15 (step S2).

Then, the traction controller 15 first refers to a three-dimensional map (θ1.θS-β) stored in a memory (not shown) based on the opening ratio between the main throttle opening θ width and the sub-throttle opening θS. Then, an opening influence coefficient β that sets the weights of the main throttle valve THm23 and the sub-throttle valve THs 24 is determined (step S3).

Next, a filter constant α1 corresponding to the intake pipe volume V downstream from the main throttle valve THm23, which has been calculated and stored in advance, and an intake pipe volume V+ΔV downstream from the sub throttle valve THs24 are determined.
Based on the filter constant α2 corresponding to (A2) is obtained (step S4).

Then, in the traction controller 15, the throttle opening influence coefficient β obtained in step S3 above is
and each throttle valve THm determined in step S4 above 23. Based on the intake air ff1G+ and G2 with THs 24 as the reference, the actual intake air ff
1Go is determined by the above formula (83) (step S
5).

When the actual intake air amount Go for the cylinder combustion chamber 25 is calculated in this way, the basic fuel injection Jii F o is calculated by the following formula (A4) based on the ideal air-fuel ratio (A/F-14, 7).

Fo-k-c, -(A4) However, k←1/14.7.

Thereby, the traction controller 15 calculates the fuel injection time according to the basic fuel injection amount Fo and opens the fuel injection valve 201a.

That is, the target sub-throttle opening θSO is set according to the target air m A /N o , and the actual intake air fiG is determined thereby. The basic fuel injection amount Fo is calculated according to
6 is operated, the output torque of the engine 16 is controlled with high precision to the target engine torque Tel, and the driving wheel WFI? , the WFL is driven in an optimal driving state with suppressed slip.

Incidentally, the higher driven wheel speed output from the high vehicle speed selection section 37 is subtracted from the wheel speed VFR of the driving wheels in the subtraction section 55. Furthermore, the higher wheel speed output from the high vehicle speed selection section 37 is subtracted from the wheel speed VPI of the driving wheels in the subtraction section 56. Therefore, the outputs of the subtraction units 55 and 56 are estimated to be small to reduce the number of times the brake is used even during turning, and the slip of the driving wheels is reduced by reducing the engine torque.

The output of the subtraction unit 55 is multiplied by KB (0
<KB<1), and the output of the subtraction section 56 is outputted to the multiplication section 58.
After being multiplied by (1-KB) in the adding section 59, it is added to the slip amount DVFR of the right drive wheel.

At the same time, the output of the subtraction section 56 is multiplied by KB in a multiplication section 60, and the output of the subtraction section 55 is multiplied by (1-KB) in a multiplication section 61, and then added in an addition section 62 to produce the left driving wheel. The slip is 1 DVPL. As shown in FIG. 13, the variable KB changes according to the elapsed time t from the start of traction control, and when the traction control starts, rO
, 5J, and as the traction control progresses, it approaches "G8". In other words, when reducing the slip of the driving wheels by braking, it is possible to apply the brakes to the side wheels at the same time when braking starts, thereby reducing the unpleasant steering shock that occurs when braking starts on a split road, for example. . On the other hand, the brake control continues and the above KB
The operation when becomes ro, 8J will be explained.

In this case, when slip occurs in only one drive wheel, brake control is performed by recognizing that slip has occurred in the other drive wheel by 20% of that of the one drive wheel. This is because if the brakes on the left and right drive wheels are made completely independent, only one drive wheel will be braked, and when rotation decreases, the opposite drive wheel will slip and brake due to the action of the differential, and this operation will be interrupted. This is because it is repeated and is not desirable. The slip amount DVPR of the right drive wheel is differentiated by the differentiator 63 to calculate its temporal change amount, that is, the slip acceleration GFR, and the slip ff1DVPL of the left drive wheel is differentiated by the differentiator 63.
4 to calculate the amount of change over time, that is, the slip acceleration GFL. The slip acceleration GFR is calculated by the brake fluid pressure change ff1 (ΔP) calculation unit 6.
5, and GFR (GFL)- shown in FIG.
With reference to the ΔP conversion map, the amount of change ΔP in brake fluid pressure for suppressing slip acceleration GPR is determined.

Similarly, the slip acceleration GFL is determined by the amount of change in brake fluid pressure (ΔP)
The amount of change ΔP in brake fluid pressure for suppressing slip acceleration GPL is determined.

Furthermore, the slip acceleration GFI? output from the ΔP calculating section 65? The amount of change Δ in brake fluid pressure to suppress
P is given to the ΔP-T conversion unit 67 that calculates the opening time T of the inlet valve 17i and the outlet valve 17o when the switch S2a is closed, that is, when the control start/end determination unit 69 determines that the control start condition is satisfied. , when ΔP is positive, the opening time of the inlet valve 17i is calculated, and when ΔP is negative, the opening time of the outlet valve 170 is calculated. That is, the valve opening time T calculated by this ΔP-T converter 67 is taken as the brake operation time FR of the right drive wheel WFR. Similarly, the above ΔP
The amount of change ΔP in the brake fluid pressure for suppressing the slip acceleration GFL output from the calculation unit 66 is determined by the switch S2.
ΔP- to calculate the opening time T of the inlet valve 18i and the outlet valve 18o when the control start condition b is closed, that is, when the six control start/end determination units determine that the control start condition is satisfied.
When ΔP is positive, the opening time of the inlet valve 18i is calculated, and when ΔP is negative, the opening time of the outlet valve 180 is calculated. In other words, the valve opening time T calculated by this ΔP-T converter 68 is taken as the brake operation time FL of the left drive wheel WPL. This prevents the left and right drive wheels WFR, WPL from causing more slip.

In addition, in Fig. 14, when applying the brakes when turning, in order to strengthen the brakes on the inner drive wheels,
The inner wheel side when turning is shown by a broken line a. In this way, when turning, the load shifts to the outer wheel side and the inner wheel side becomes prone to slipping. This can sometimes prevent the inner ring from slipping.

For example, when a vehicle starts and accelerates on a low-μ road such as a snow-packed road, acceleration slip occurs in the driving wheels WPR and WFL due to an increase in engine output as the accelerator pedal is depressed, and the amount of slip DV+ is used to determine the slip. Value storage section 71
When the value exceeds the pre-stored slip determination value α, the slip determination section 70 outputs a slip determination signal (DVI>α) to the control start/end determination section 69. Then,
The control start/end determination unit 69 determines that slip suppression control of the driving wheels is required, and switches S1 and S2a.
, S2b is closed. As a result, the drive wheel WPR
, WPL, engine torque control according to the slip amount DV of WPL, and slip control by braking control are started.

On the other hand, in the state after the slip control is started, for example, as the main throttle valve THII2B is closed by returning the accelerator pedal, the engine output torque decreases and the slip factor of the drive wheels WPR, WFL is eliminated. The slip amount DVI is the slip judgment value storage unit 7
When the value becomes equal to or less than the slip determination value α stored in advance at 1, the slip determination unit 70 outputs a slip determination signal (DVI≦α) to the six control start/end determination units. Then, the control start/end determination unit 69 determines that the slip suppression control of the drive wheels is no longer necessary, and switches S1 and S2.
a. Open S2b. As a result, the drive wheel WF
The engine torque control according to the slip m DV of R and WFL and the slip control by braking control are ended.

Here, when the six control start/end determining sections determine the end of the control, the sub throttle valve THs 24
The opening degree θS is gradually controlled in the full-open direction, and the sub-throttle is on standby in a state where the full-open detection signal (ON) is obtained from the full-open 5W29.

Therefore, according to the acceleration slip prevention device for a vehicle configured as described above, it is possible to appropriately perform engine torque control and braking control, reliably suppress slip occurring in the drive wheels, and improve the acceleration performance of the vehicle. In addition, by using the fuel control method according to the present invention, a throttle opening influence coefficient β is determined according to the opening ratio between the main throttle opening θm and the sub-throttle opening θS, and this opening influence coefficient β
By adding the intake air RG based on the main throttle valve THm23 and the intake air amount G2 based on the sub throttle valve THs24 with weighting, the cylinder combustion chamber 2
Since the actual intake air amount Go for 04 is obtained, the accurate intake air amount Go is calculated taking into account the actual intake pipe 8 opening (V-V + ΔV) that constantly changes according to the fluctuations of each throttle opening θl and θS. This makes it possible to perform reliable slip prevention control through highly accurate fuel injection control.

[Effects of the Invention] As described above, according to the present invention, in an engine including main and sub throttle valves arranged in series in the intake flow path in the intake pipe, and a fuel injection valve provided for each cylinder, the above two effects can be achieved. an air amount measuring means provided in an intake flow path upstream of the throttle valve and measuring the amount of air flowing into the intake flow path; and a throttle opening detection means for detecting the opening degrees of each of the main and sub-throttle valves; Means for determining the opening degree influence coefficient on the intake air amount according to the opening ratio of the above-mentioned main and sub-throttle valve openings, and two types corresponding to different intake pipe volumes from the above-mentioned main and sub-throttle valves to the intake valve. and means for weighting the intake air amount for each of the main and sub throttle valves calculated using these two filter constants by the opening influence coefficient and adding them to obtain the actual intake air amount. and a means for determining the basic fuel injection amount based on this actual intake air amount, so even if the MPI engine employs a two-throttle intake system, the accurate intake air amount can always be determined and high It is possible to provide a fuel 1.1j control method that makes it possible to obtain an accurate fuel injection amount.

[Brief explanation of drawings]

FIG. 1(A) is an overall configuration diagram of a vehicle acceleration slip prevention device according to an embodiment of the fuel control method of the present invention.
Figure (B) is a configuration diagram showing the engine intake system in Figure 1 (A), Figure 2 is a block diagram showing the control of the traction controller in Figure 1 divided into functional blocks, and Figure 3 is a block diagram showing the centripetal acceleration. A diagram showing the relationship between GY and the variable KG, FIG. 4 is a diagram showing the relationship between the centripetal acceleration GY and the variable K, and FIG. 5 is a diagram showing the relationship between the centripetal acceleration GY and the slip correction amount Vg.
FIG. 6 is a diagram showing the relationship between the temporal change amount ΔGY of centripetal acceleration and the slip correction amount vd, FIGS. 7 to 12 are diagrams showing the relationship between the vehicle body speed VB and the variable Kv, and FIG.
The figure shows the change over time in the variable KB from the start of brake control, and Figure 14 shows the change over time in the amount of slip 1GFR (GF
A diagram showing the relationship between the amount of change ΔP in brake fluid pressure and the amount of change ΔP in brake fluid pressure,
15 and 18 are diagrams showing the relationship between slip ratio S and road surface friction coefficient μ, respectively. FIG. 16 is a diagram showing Tlim- characteristics. FIG. 17 is a diagram showing T II + nVB characteristics. Figure 20 shows the state of the vehicle when turning, Figure 20 shows the target engine torque-engine rotation speed map for determining the target air amount, and Figure 21 shows the engine rotation speed Nc characteristic of coefficient Ka. , FIG. 22 shows the coefficient Kt
FIG. 23 is a diagram showing the atmospheric pressure characteristics of the coefficient Kp, FIG. 24 is a diagram showing the intake air temperature characteristics of the coefficient Ka', and FIG. 25 is a diagram showing the intake air temperature characteristics of the coefficient Kp. A diagram showing a target A/N-engine rotation speed map, FIG. 26 is a diagram showing engine rotation speed characteristics with a proportional gain Kp, FIG. 27 is a diagram showing engine rotation speed characteristics with an integral gain of 1, and FIG. 28 is a diagram showing engine rotation speed characteristics with an integral gain of 1. FIG. 29 is a diagram showing the engine rotation speed characteristic of the differential gain Kd, FIG. 29 is a diagram showing the engine rotation speed characteristic of the conversion gain, and FIG. 30 is a graph showing the equivalent target throttle opening - raw throttle opening for determining the basic target sub-throttle opening. Figure 31 shows the main throttle opening θ■ and the sub-throttle opening θS in the above fuel control method.
FIG. 32 is a flowchart showing the basic fuel injection amount determination operation based on the above fuel control method. WPI? , WFL... Drive wheel, WRR, WRL...
- Driven wheels, 11 to 14...Wheel speed sensor, 15...
・Traction controller, 16...engine, 2
2...Intake pipe, 22a...Surge tank, 23...
・Main throttle valve THm, 24...Sub-throttle valve THs, 24M...Motor, 25...Motor drive circuit, 26...Main throttle position sensor (TPS)
I), 27... Sub throttle position sensor (T
PS2), 28...Main throttle idle SW, 2
9... Sub-throttle fully open SW, 30... Air flow sensor (AFS), 30a... Negative pressure sensor, 45.4
6... Correction torque calculating section, 47c... Reference torque calculating section, 50... Engine torque calculating section, 69... Control start/end determining section, 70... Slip determining section, 71
...Slip judgment value storage unit, 81a to 81d...Fuel injection injector, 82...Engine control unit (ECU), 83...Engine rotation sensor,
84... Engine torque sensor, 201a... Intake valve, 201b... Exhaust valve, 203... Piston, 2
04... Combustion chamber, 502... Target air amount calculation unit, 5
04...Equivalent target throttle opening calculation unit, 505...
・Target throttle opening calculation unit, Sl, S2a, 52b-
··switch.

Claims (1)

[Claims] In a fuel control system for an engine that is equipped with main and sub-throttle valves arranged in series in the intake flow path in the intake pipe, and a fuel injection valve is provided for each cylinder, the throttle valve is installed in the intake flow path upstream of the two throttle valves. an air amount measuring means for measuring the amount of air flowing into the intake flow path; a throttle opening detecting means for detecting the respective opening degrees of the main and sub throttle valves; and opening degrees of the main and sub throttle valves. a means for determining an opening influence coefficient on the intake air amount according to the ratio; a means for determining two types of filter constants corresponding to different intake pipe volumes from each of the main and sub throttle valves to the intake valve; Means for obtaining an actual intake air amount by weighting and adding the intake air amount for each of the main and auxiliary throttle valves calculated using the filter constant using the above-mentioned opening influence coefficient, and calculating the basic fuel amount based on the actual intake air amount. 1. A fuel control method characterized by comprising: means for determining an injection amount.