JPH04171242A - Engine output control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an engine output control device that regulates engine output according to vehicle driving information. A phenomenon occurs in which engine output is not sufficiently transmitted to the road surface due to slipping. Such slips frequently occur on slippery road surfaces. In order to prevent the occurrence of such slip, an engine output control device is known that reduces the engine output depending on the road surface condition to prevent the occurrence of slip of the drive wheels during acceleration.

In such engine output control devices, as a means to reduce engine output, the opening degree of the throttle valve is controlled by a separate link system with priority over the accelerator link system, or the throttle valve is placed on the intake path in two stages, front and rear. There is one placed in. Further, engine output is reduced by cutting fuel in a predetermined cylinder out of all the cylinders of the engine to perform cylinder control, or by retarding the ignition timing.

(Problem to be solved by the invention) However, when regulating the opening of the throttle valve, it is necessary to add a drive mechanism to drive the throttle valve, so it is necessary to partially change the engine hardware. This makes it difficult to reduce costs, and there is also the problem that air flow control using a throttle valve has poor responsiveness.

Furthermore, when performing engine output reduction control that increases or decreases the number of fuel cut cylinders, the number of fuel cut cylinders and ignition timing are determined based on a preset constant table (map) for the target engine torque, and then Based on this, the ignition angle (ignition timing) and the injection amount of each injector are controlled.

However, if the amount of ignition retard is increased only by considering torque reduction for output regulation, the exhaust temperature will increase rapidly, and the temperature of objects in the exhaust path, such as catalysts and sensors, may exceed the allowable limit. There is a problem that the durability of the exhaust system is reduced. Moreover, when the ignition means is a two-plug simultaneous ignition system, if the ignition timing exceeds TDC due to retard, backfire is likely to occur at the beginning of the intake process in other cylinders with a 360° phase difference, which is a problem. It has become.

An object of the present invention is to provide an engine output control device that can prevent thermal deterioration of an exhaust system due to a rise in exhaust temperature.

(Means for Solving the Problem) In order to achieve the above-mentioned object, the present invention includes a target engine torque calculation means for calculating a target engine torque according to driving state information and driving state information of the vehicle, and a fuel injection control means for injecting a predetermined amount of fuel into each cylinder of the engine; an ignition control means for injecting a predetermined amount of fuel at a predetermined ignition angle for each cylinder of the engine of the vehicle; An imaginary torque calculation means for calculating expected torque, an output regulation amount calculation means for calculating a required torque reduction amount from the torque deviation between the target engine torque and the expected torque, and a fuel cut number of cylinders according to the required torque reduction amount. and ignition timing calculation means that calculates the ignition timing based on the ignition angle corresponding to the residual by subtracting the loss torque corresponding to the number of fuel cut cylinders from the target engine torque. and ignition timing regulating means for regulating the ignition timing according to the set exhaust temperature so that the ignition timing does not exceed a limit retard amount at the set exhaust temperature, and the fuel injection control means for regulating the ignition timing according to the number of fuel cut cylinders. and engine output control means for controlling the ignition control means in accordance with the ignition timing.

(Function) The output regulation amount calculation means calculates the necessary torque reduction amount from the torque deviation between the target engine torque from the target engine torque calculation means and the predicted torque from the expected torque calculation means,
The cut cylinder number calculation means calculates the number of fuel cut cylinders according to this required torque reduction amount, and the ignition timing calculation means calculates the residual by subtracting the loss torque equivalent to the number of fff4 cut points from the target engine torque, and calculates the residual. The ignition timing is calculated based on the ignition angle equivalent to the difference, and the ignition timing regulating means regulates the ignition timing according to the set exhaust temperature so that the ignition timing does not exceed the limit retard amount at the set exhaust temperature. The output control means can control the fuel injection control means according to the calculated number of fuel cut cylinders, and can drive and control the ignition control means according to the calculated ignition angle.

(Embodiment) The engine output control device shown in FIG. 1 is installed in a front wheel drive vehicle. This engine output control device includes an engine controller (ECI controller) 16 that controls the fuel supply system and ignition system of the engine 10, and a traction controller 1 that calculates a target output value according to various driving information of the vehicle.
5, which work together to control the output of the engine 10.

Here, the engine 1o outputs air-fuel ratio (A/F) information obtained from an air-fuel ratio sensor 2 disposed in its exhaust path to an engine controller 16, and this controller 16 outputs fuel according to the air-fuel ratio information. A configuration is adopted in which the amount of fuel to be supplied is calculated, the injection nozzle 3 injects and supplies the amount of fuel to the intake passage 4 in a timely manner, and the ignition plug 22 performs ignition processing in a timely manner.

The engine 10 has six cylinders each with a fuel injection device for each cylinder, and its intake path 4 includes an air cleaner 5 and an intake pipe 6.
A throttle valve 7 is disposed in the middle. A throttle sensor 8 is attached to the throttle valve 7. The exhaust path 1 is provided with an air-fuel ratio sensor 2, a catalyst 24 downstream thereof, and a muffler (not shown).

The vehicle is provided with left and right front wheels WFL and WFR as driving wheels, and left and right rear wheels WRL and WRR as driven wheels. These left and right front wheels WFL and WFR indicate the wheel speed V of the left and right front wheels.
Wheel speed sensors 1.1.12 that output FL and VFR are provided in opposition to each other, and the left and right rear wheels WRL and WRR have wheel speed sensors 13 that output wheel speeds VRL and VRR of the left and right rear wheels.
, 14 are arranged opposite to each other.

Each of these wheel speed information is transmitted to the traction controller 15.
is input.

In addition, the traction controller 15 is connected to a throttle sensor 8 that generates throttle opening information, an air flow sensor 9 that generates intake air amount information, and a crank angle sensor 20 that generates a unit crank angle signal and engine rotation speed Ne information from that signal. has been done.

Furthermore, this traction controller 15 sends a request engine torque T ref to the engine controller 16, which will be described later.
In addition to outputting o, data from each sensor can also be output.

On the other hand, data from each sensor via the traction controller 15 is input to the engine controller 16, and the air-fuel ratio (A/
F) Information is entered. Furthermore, a water temperature sensor 19 that emits temperature information of engine cooling water. An intake temperature sensor 17 that emits intake air temperature information, an atmospheric pressure sensor 18 that emits atmospheric pressure information,
A knock sensor 21 that generates knock information about the engine 10 is connected.

The main parts of the traction controller 15 and the engine controller 16 are each made up of a microcomputer, and in particular, the traction controller 15 is
A required engine torque TrefO is calculated according to the required engine torque calculation program shown in the figure, and the value is output to the engine controller 16. The engine controller calculates control values in accordance with the control programs shown in FIGS. 13 to 16, drives the injection nozzles 15 of the cylinders other than the fuel cut cylinders to achieve a predetermined injection amount, and controls the ignition circuit 23 in a timely manner. The spark plug 22 is driven to ignite via.

Here, the traction controller 15 has a function as a required engine torque calculation means, and calculates the required engine torque T re according to the driving state information and traveling state information of the vehicle.
Calculate fo.

On the other hand, the functions of the carrot controller 16 will be explained with reference to FIG.

As shown in FIG. 2, this controller 16 includes at least a target engine torque calculation means, an expected torque calculation means, an output regulation amount calculation means, a cut cylinder number calculation means, an ignition calculation means, and an ignition timing regulation means. and has a function as an engine output control means.

FIG. 3 shows the functions of the engine output control device shown in FIG. 1. Here, the target engine torque calculation means calculates the target engine torque T ref based on the required engine torque T refo and the water temperature loss correction value Twt according to the driving state information and traveling state information of the vehicle. The expected torque calculation means calculates the current expected torque Texp based on the intake air amount A/N of the engine 10, and the output regulation amount calculation means calculates the required torque reduction amount Tred from the torque deviation between the target engine torque T ref and the expected torque T exp. Calculate.

The cut cylinder number calculation means calculates this required torque reduction amount T re
The number of fuel cut cylinders Nfc is calculated according to d, and the ignition angle calculation means subtracts the loss torque NfcXTfcl corresponding to the number of fuel cut cylinders Nfc from the target engine torque T ref to find the residual difference, and the ignition angle corresponding to the residual difference is calculated. That is, the torque Tret to be corrected by retard and the required retard amount θ
ret and the ignition timing θadν. The ignition timing regulating means regulates one ignition timing θadv according to the set exhaust temperature so that the ignition timing θadv does not exceed the limit retard amount at the set exhaust temperature. In addition, here, Fig. 10(a)
Using the limit retard amount calculation map at the set exhaust temperature (850° C.), retard exceeding TDC is particularly prohibited here. The engine output control means drives and controls the injection nozzle 3 as a fuel injection control means with the calculated number of fuel cut cylinders Nfc, and the calculated ignition timing θadν
The spark plug 22 serving as the ignition control means can be driven and controlled according to the ignition control means.

In particular, here, the ignition angle calculation means calculates the calculated ignition timing e.
It is possible to perform knock correction on ADV and control retard correction.

In the above, the current expected torque T exp is the intake air amount A
/N, but instead of this,
Intake negative pressure PB, throttle opening θ, etc. may also be used.

Here, calculation formulas used by the engine controller 16 in the following control will be sequentially explained.

Target engine torque T ref is calculated using equation (1).

Tref= Trefo+ Ttyt+ Tap+ T
1ac”・(1) Here, Trefo is the required torque, Ttit is the water temperature correction torque that compensates for friction loss torque (uses a map set so that the value Twt increases as the water temperature decreases), and Tap is the atmospheric pressure correction torque ( A map is used in which the value Tap increases as the atmospheric pressure decreases), and '14ac indicates the air conditioner correction torque (fixed value, equivalent to the load at idle).

The expected torque T exp is calculated using equation (2).

Texp= a ) is shown.

The characteristics are shown as non-reduced torque in FIG.

The required torque reduction amount T red is expressed by equation (3), T red
The number of fuel-cut cylinders (number of body cylinders) Nfc corresponding to each is calculated using equation (4).

Tred=Tref−Texp”(3)Nfc=Tr
ed/Tfcl...(4) Here, equation (3) is calculated from equations (1) and (2), and Tfcl is calculated using equation 5), which indicates the amount of torque change per cylinder. Note that Nfc is determined to be an integer value using a map as shown in FIG.

Tfcl= a X Abn/6'' (5) The torque Tret to be corrected by retard is calculated by equation (6), the required retard amount θret is calculated by equation (7), and the ignition timing θadv is calculated by equation (8).

Tret= Tred −NfcX Tfcl” (6)
θret=TretXKretX(6-Nfc)+θr
etc.

...(7) θadv=θb+Max(θwt, θap) 10at-
θret...(8) Here, Tfcl is the amount of torque reduction per cylinder, Kre
t is the retard gain (a map that can be calculated according to A and the rotational speed Ne is created in advance), and θret.

is the invalid retard amount (prepare a map that can be calculated according to A and rotation speed Ne), θb is the basic ignition timing,
θwt and θaP+θat respectively indicate ignition timing correction values based on water temperature, atmospheric pressure, and intake air temperature, and these are calculated in the same way as in a normal routine.

Note that a knock correction value may also be added to this ignition timing correction value, and a setting may be made such that a predetermined correction amount is added at the time of knock. Ineffective retard amount θret.

In this case, a region where the torque reduction effect is small due to retardation is set.

Here, the control processing by the traction controller 15 and the engine controller 16, both of which are driven with the key on, will be explained along with the control programs shown in FIGS. 12 to 16.

The traction controller 15 has a main routine (not shown) that determines the failure of each sensor and circuit, sets initial values for each area, performs initial settings, receives the output of each sensor, and sets a controller for each area, etc. is being processed. A required engine torque calculation routine is entered at each predetermined interrupt timing (time interrupt) during that time.

Here, each data is received from each wheel speed sensor and varnished at predetermined addresses VFR, VFL, VRIL, and VRL.

In step a2, the vehicle body speed Vc is determined and stored from the left and right average wheel speeds of the non-driving wheels. Furthermore, the longitudinal acceleration ac is calculated by differentiating the vehicle speed Vc. Then, in the peak value acMA of this longitudinal acceleration ac, the theory (μ
mS characteristic,), the friction coefficient of the road surface is at its maximum at that time, so the peak value a of this longitudinal acceleration
Set cMAX as the estimated value of the friction coefficient of the road surface. Then, find the slip ratio S at that point. Then, the target wheel speed ■1 is added with the wheel speed coal equivalent to the slip ratio S.
Calculate. When step a6 is reached, the target wheel speed vw
The target wheel acceleration Vw/dt is calculated by differentiating Vw/dt.

In step a7, the driving wheel torque to achieve the target wheel speed ■7 is determined based on the target wheel acceleration Vw/dt and according to the vehicle weight W and the tire radius R1 and the running resistance.
The required engine torque Trefo is calculated by considering the drive wheel torque Tw and the transmission gear ratio, and outputted to the engine controller ]-6.

In the ECI main routine of the engine controller 16, first, initial settings (not shown) are made, and detection data from each sensor is read and taken into a predetermined area.

In step b2, whether or not the fuel cut zone is reached is determined based on the engine speed Ne and the engine load information (in this case, the intake air amount A/
N) is determined, and in the case of a cut, the process proceeds to step b3, where the air-fuel ratio feedback flag FBF is cleared, the fuel cut flag FCF is set to 1, and the process proceeds to step blO.

When step b5 is reached as it is not a fuel cut.

The fuel cut flag FCF is cleared, and it is determined whether the well-known air-fuel ratio feedback condition is satisfied. If the current operating information (A
/N, N ) is calculated, this value is input to the address KAF, and the process proceeds to step b9.

When the air-fuel ratio feedback condition is satisfied and step b7 is reached, the correction value K corresponding to the normal feedback control constant is determined based on the output of the air-fuel ratio sensor 2.
Calculate FB.

Then, this value is taken into address KAF and step b9
Proceed to.

In step b9, other fuel injection pulse width correction coefficients K
DT and the dead time correction value TD of the fuel injection valve are set according to the operating condition, and each correction value for calculating the ignition timing θadv used in equation (8) is calculated in step bl.
Proceed to O. The correction values include a water temperature correction value θwt, which is advanced in response to a decrease in water temperature, an atmospheric pressure correction value θap, which is advanced in response to a decrease in atmospheric pressure, and an intake temperature correction value, which is advanced in response to a decrease in intake temperature. Each sensor output is calculated using θat and stored in a predetermined area.

In step blo, the torque angle is set based on a predetermined map (an example of which is shown in a characteristic diagram in FIG. 9) so that the torque angle increases in accordance with the engine speed Ne.

Thereafter, the routine proceeds to step bll, an engine output regulation routine, and thereafter returns to step b1.

By the way, in the engine output regulation routine, Fig. 14 (
As shown in a) and (b), in step c1, TCL
It is checked whether the medium flag flag is set, and if it is not set, the process proceeds to step c4, and it is determined whether or not the TCL start condition is satisfied. Conditions for this determination include that there is a request signal from the TCL, that the gear position is other than N or R, that the idle switch is off, and so on. Here, if the start condition is not satisfied, the process returns to the main routine, and if it is satisfied and reaches step c5, the TCL flag is set, and then the catalyst temperature, exhaust gas temperature, etc. are initialized, and the process proceeds to step C7.

On the other hand, if the TCL flag is set in step c1,
The process advances to step C2, where it is determined whether the TCL termination condition is satisfied. This TCL termination condition is satisfied if the sensor/actuator fails, in which case the TCL flag is set in step c3 and the process returns to the main process, and if not satisfied, the process proceeds to step c7.

In step c7, loss torque (water temperature correction torque Tut, atmospheric pressure correction torque Tap, air conditioner correction torque TeaC) is added to the requested engine torque T refo from the TCL side.
Add and correct.

In steps c8 to clO, based on the intake air amount A/N, the expected torque TexP in the case where the torque is not reduced is (2
) is calculated using the formula. Then, the required torque reduction amount T red
is the expected torque Tex from the target engine torque T ref
Calculate by subtracting p by equation (3), and the number of fuel cut cylinders Nfc is calculated by dividing the required torque reduction amount T red by Tfcl (4
) and its torque reduction amount per cylinder T fcl (5
) is calculated using the formula. Note that Nfc is determined to be an integer value using a map as shown in FIG. After this step e
When it reaches ll, here the seventh cut is made according to the number of body cylinder cuts.
The cut cylinder number is determined based on the map shown in the figure. The map in Figure 7 is based on the structure of the engine 10 (in this case it is a V type 6 cylinder as shown in Figure 6) and its characteristics, and takes into account the rotational balance, cooling efficiency, etc., and calculates the cylinder number corresponding to each number of cuts. It is set.

Once the cylinder number corresponding to the number of cuts is set in this way, the process proceeds to step c12.

After that, in step c12, the torque Tret to be reduced by the ignition retard is set to the required torque reduction amount T red
Equation (6) is calculated by subtracting the amount of torque reduction due to the body cylinder. Further, in step c13, the necessary retard amount θret is determined by multiplying the torque T ret to be reduced by the ignition retard, the retard gain K ret, and the number of driven cylinders (6-Nfc) to obtain the invalid retard amount θret.
Calculate equation (7), which is obtained by adding to. Furthermore, in step c14, the ignition timing θadv is changed to the basic ignition timing θ.
b is the ignition timing correction value (θw
t, θaP+θat), and subtract the required retard amount θret.

Proceeding to step c15, a determination is made as to whether or not the ignition timing exceeds the limit retard amount at the set exhaust temperature (here set at 850° C.) using the map shown in FIG. 10(a). This map is engine speed Ne
and intake air amount A/N are set in advance as parameters. for example. When Ne=3000 and the intake air amount A/N is WOT, the limit ignition timing is θadv=10, and if the ignition timing θadv calculated in step C14 from this value is on the advanced side, leave the ignition timing θadv as it is,
Proceed to step c17.

On the other hand, if it is determined in step c15 that the current ignition timing θadv has been retarded beyond the limit retard amount, the process proceeds to step c16, where the retard limit value (850°C) on the map of FIG. 10(a) is read and this value is determined. In order to regulate the retard, set the current ignition timing θadv, and step c1
Proceed to step 7.

Here, only when the engine rotation speed is less than 200 rpm at 2°3 cylinder deactivation, which is the operating range where knock is likely to occur,
Proceed to step c18.

Here, if a knock signal is received, the ignition timing θad
Find v using the map in FIG. 10(b), and proceed to step c1.
Rewrite and correct the values in step 4. In this knock limit map, the ignition timing θadv with the engine speed Ne and the number of cylinders as parameters is set in advance according to the engine speed and the number of cylinders. After this step c18, the process returns to the main routine.

During this ECI main routine, the injector driving routine shown in FIG. 15 and the ignition driving routine shown in FIG. 16 are performed.

The injector drive routine reaches steps d1 and 2 at a predetermined crank pulse interruption, takes in the intake air amount A/N and the engine rotational speed Ne, returns when the fuel cut flag FCF is 1, and proceeds to step d4 when it is 0. Here, the basic fuel pulse width TB is set, and the main pulse width data Tinj=T++XKAFXKDT+TD is calculated,
Proceed to step d6.

Here, among the injector drive drivers, Tinj is set only to the driver of the cylinder that is not set as a fuel cut cylinder, the driver is triggered, the injection nozzle 3 injects fuel, and the process returns.

This process reduces the torque by the number of fuel cut cylinders Nfc.

On the other hand, step e1 occurs at the crank pulse interrupt in FIG.
When this is reached, a dwell angle at which the primary current is caused to flow by the dwell angle, which is the primary current energizing crank angle width, is set in the dwell angle counter. In step e2, the target ignition timing θa is input to the ignition timing counter that can output the ignition signal at the target ignition angle.
dv is set.

As a result, each counter drives the ignition circuit 23 when counting a predetermined crank pulse, and causes the ignition plug 22 to ignite. In this ignition process, the ignition timing θadv
The torque Tret to be reduced is reduced with good responsiveness by the ignition retard equal to the necessary retard amount θret included in the ignition retard. In addition, FIG. 11 shows the change characteristics of the corrected torque (corresponding to the target engine torque T ref) due to the retard process of the ignition timing θadv at the engine rotation speed N e = 30.
At 0 rpm, the intake air amount Ac is shown as a parameter. In this case, the exhaust temperature increases as the exhaust temperature increases, and in the chain line region where the ignition timing e adv is BTDCI O', the exhaust temperature reaches 850, which may cause thermal deterioration of objects in the exhaust path. °C, and in this case, it is necessary to set the ignition timing θadv at the limit retard amount to 10°.

(Effects of the Invention) As described above, the present invention calculates the required torque reduction amount from the torque deviation between the target engine torque and the expected torque, calculates the number of fuel cut cylinders according to this required torque reduction amount,
Calculate the residual by subtracting the torque loss equivalent to the number of fuel-cut cylinders from the target engine torque, calculate the ignition timing based on the ignition angle equivalent to the residual, and ensure that the ignition timing does not exceed the limit retard amount at the set exhaust temperature. The ignition timing is regulated according to the set exhaust temperature, the engine output control means controls the fuel injection control means according to the calculated number of fuel cut cylinders, and the ignition control means are respectively driven and controlled according to the calculated ignition timing. Since this is made possible, it is possible to achieve a reduction in output according to the number of stopped cylinders and a reduction in output according to the amount of ignition retard, and in particular, there is an advantage that thermal deterioration of the exhaust system due to a rise in exhaust gas temperature can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an engine output control device as an embodiment of the present invention, FIG. 2 is a block diagram of a control means of the present invention, and FIG. 3 is a control means of the output control device of FIG. 1. Fig. 4 is a slip ratio-friction coefficient characteristic diagram of a vehicle equipped with the above device, Fig. 5 is an explanatory diagram of the cylinder number setting map used in the above device, and Fig. 6 is a diagram showing the same as the above device. 7 is an explanatory diagram of the cylinder number setting map used in the above device. FIG. 8 is an explanatory diagram of the driving range calculation map used in the above device. An explanatory diagram of each dwell calculation map used in the above device,
Figure 10 (a) is an explanatory diagram of the ignition timing calculation map at the retard limit used in the same device, and Figure 10 (b) is an illustration of the ignition timing calculation map at the knock limit used in the same device. 11 is a diagram showing the torque characteristics when the ignition timing is retarded using the intake air amount A as a parameter; FIG. 12 is a flowchart of the required engine torque calculation program executed by the traction controller used in the above device; FIG. 1 to 16 are flowcharts of each control program executed by the engine controller used in the above device. 2... Air-fuel ratio sensor, 3... Injection nozzle, 7...
Throttle valve, 8...throttle position sensor,
9... Air flow sensor, 10... Engine, 15
... Traction controller, 16... Engine controller, 22... Spark plug, T refo・
...Required engine torque, θadv...Ignition timing, A
/F...air-fuel ratio, T ref...target engine torque, Texp...expected torque, Nfc...number of fuel cut cylinders, θret...necessary retard amount, Tred
... Necessary torque reduction amount, T ret ... Torque to be corrected by retard, V work ... Exhaust temperature. 7'yF) 4% Light 4 Illusion V3. , E (night rule) Mo6 spot sale q phantom e Fig. 10 (a) (b) 3000 rr @ 1st term (dQ) Tokipu/Enteru 1t7 days〒5ヅ4shi〕 rδ) Rideto ID diagram

Claims (1)

[Claims] Target engine torque calculation means for calculating a target engine torque according to driving state information and driving state information of the vehicle;
a fuel injection control means for injecting a predetermined amount of fuel into each cylinder of the engine of the vehicle; an ignition control means for injecting a predetermined amount of fuel at a predetermined ignition angle for each cylinder of the engine of the vehicle; expected torque calculation means for calculating the current expected torque based on the target engine torque, output regulation amount calculation means for calculating the required torque reduction amount from the torque deviation between the target engine torque and the expected torque, and a fuel cut according to the required torque reduction amount. A cut cylinder number calculation means for calculating the number of cylinders, and an ignition timing that calculates a residual difference by subtracting a loss torque corresponding to the number of fuel cut cylinders from the target engine torque and calculates an ignition timing based on an ignition angle corresponding to the residual difference. calculation means,
ignition timing regulating means for regulating ignition timing according to a set exhaust temperature so that the ignition timing does not exceed a limit retard amount at a set exhaust temperature; and controlling the fuel injection control means according to the number of fuel cut cylinders. and engine output control means for controlling the ignition control means according to the ignition timing.