JPH0381543A - Emergent decrease method for engine output of vehicle - Google Patents

Abstract

PURPOSE:To prevent application of overvoltage on a spark ignition device by providing a cut-off means of fuel supply to an engine for emergently decreasing engine output, and providing a throttle opening decreasing means with an electronic device actuated prior to fuel cut. CONSTITUTION:An intake passage 30 is provided with a main throttle valve 36 opened or closed according to a step-in quantity of an accel pedal 38, and a sub-throttle valve 42 controlled to open or close with an electronic control device 46. A fuel injector 34 has its valve opening timing and valve opening duration controlled by a control signal from a fuel injection control device 40, basically controlled according to an intake air quantity. When fuel supply is cut off for emergent decrease of engine output, the throttle opening of the valve 42 is automatically decreased with the control device 46 prior to fuel cut, and hereafter fuel is cut. Therefore, after air pressure in the engine cylinder largely decreases, fuel is cut off, and voltage rise generated in a spark ignition device is cancelled.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to automatic driving control by an electronic control device of a vehicle such as an automobile, and more particularly to an automatic driving control method for urgently reducing engine output.

Conventional TechnologyIn order to greatly improve various performance in driving vehicles such as automobiles beyond the range achieved by the driving skills of ordinary drivers, electronic control equipment is used to control the internal combustion inside the vehicle. Applications have been developed for various operating parts including engines. One type of automatic driving control for such vehicles is to automatically reduce engine output when the vehicle's drive wheels skid beyond a set value relative to the road surface.
Temporarily shutting off the supply of fuel to the J fuel engine has already been proposed as one method of so-called traction control (for example, Jikai II/(60-1047'30)). In addition to the above-mentioned traction control, emergency reduction of engine output by automatic control may be carried out for the sake of vehicle driving safety when the speed exceeds a certain limit. This may be done to protect the internal combustion engine from damage if the engine speed exceeds certain permissible limits.

Problems to be Solved by the Invention It is easy to urgently cut off the supply of fuel to an internal combustion engine by means of a 1-1 dynamic control device in order to urgently reduce the engine output as necessary. However, the reason why the above-mentioned traction control is insufficient and the large slippage of the driving wheels relative to the amount of pedal operation occurs is generally caused by the driver pressing the accelerator pedal too hard and the throttle valve installed in the intake passage of the internal combustion engine being wide open. or when the vehicle speed or engine speed is increasing, when an emergency cutoff of fuel is desired.
The accelerator pedal must have been pressed down heavily.

When the accelerator pedal is depressed greatly and the throttle valve in the intake passage of a 1-no-1 combustion engine is wide open, a large amount of air is sucked into the cylinder chamber of the internal combustion engine. The air pressure of
This value is considerably higher than the standard air pressure in the cylinder chamber during the standard driving period, which covers most of the driving period of the vehicle, when the accelerator pedal is lightly depressed and the throttle valve is opened moderately. If the fuel supply to the cylinder chamber is cut off while the air pressure inside the cylinder chamber is relatively high, the voltage applied to the spark ignition device, which is generally about 25 kV, increases by about 3 to 5 kV. do.

Therefore, when the accelerator pedal is pressed heavily and the air pressure in the cylinder chamber of the internal combustion engine is higher than during normal operation, the fuel cutoff causes this additional voltage increase! When W- occurs, the voltage applied to the spark ignition system increases significantly compared to normal operation. If not, there is a risk of damage to the spark ignition device due to overpressure due to fuel cut-off.
Furthermore, when a spark ignition device is designed taking such a voltage increase into consideration, the cost of the spark ignition device naturally increases.

SUMMARY OF THE INVENTION The present invention solves the problem of the voltage increase applied to the spark ignition device when an emergency fuel cutoff is performed to reduce the engine output as described above. The objective is to solve the problem by modifying the control operation of the electronic control device, that is, the calculation process of the electronic computer, without requiring the addition of sophisticated hardware.

According to the present invention, such an object is to urgently reduce the engine output in a vehicle equipped with an internal combustion engine in which the throttle opening degree is controlled by a combination of accelerator pedal depression operation and automatic control operation by an electronic control device. This is achieved by a method characterized by cutting off the supply of fuel to the internal combustion engine in order to urgently reduce the engine output, and reducing the throttle opening by the electronic control device prior to cutting off the fuel. be done.

Operation and Effect of the Invention Modern vehicles such as automobiles equipped with electronic automatic control devices leave control of the output of the internal combustion engine, which affects many of the various driving performances, entirely to the free will of the driver. In order to make corrections to the amount of accelerator pedal depression by the driver in consideration of various parameters related to the driving environment and driving state of the vehicle, the intake passage of the internal combustion engine is designed to open and close according to the amount of depression of the accelerator pedal. The main throttle valve is connected in series with a sub-throttle valve that is opened and closed under automatic control of the vehicle by an electronic control device, or the throttle valve is opened and closed based on the combination of the amount of depression of the accelerator pedal and the control output of the electronic control device. It has a so-called linkless throttle valve that is controlled, and the throttle opening of the internal combustion engine is controlled by pressing the accelerator pedal (1□1) with the intervention of a 7L child control device. The method of the present invention as described above can be implemented in a medium-sized vehicle equipped with such a 71i control device by making software modifications to the operating program of the electronic control device.

As mentioned above, when fuel is cut off for emergency reduction of engine output, the throttle opening is automatically reduced by the derailleur control device in advance of each cut-off, thereby reducing the amount of water inside the cylinder chamber of the internal combustion engine. The air pressure is greatly reduced and the subsequent fuel disposal is sufficient to offset the voltage increase that occurs in the spark ignition system.

As mentioned above, the emergency fuel cutoff is performed for the purpose of urgently reducing the engine output, so the throttle opening is reduced immediately before the emergency fuel cutoff, thereby reducing the amount of air supplied to the cylinder chamber of the internal combustion engine. This reduction also meets the purpose of emergency reduction of engine output. Therefore, the throttle opening reduction operation according to the method of the present invention reduces engine output by emergency fuel cutoff, and prevents spark ignition by cutting off fuel. This simultaneously achieves two desirable effects of suppressing the voltage rise of the device.

The degree to which the throttle opening is reduced by the method of the present invention is as follows:
It may be controlled to an appropriate degree by an electronic control unit taking into account the driving condition of the vehicle at that time, thereby achieving the purpose without subjecting the vehicle to a severe impact, as will be explained in detail later. be able to.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 is an illustrative plan view showing an example of a vehicle incorporating an automatic driving control device capable of implementing the method of urgently and rapidly reducing engine output according to the present invention. Here, the automatic driving control device for a vehicle is a device that automatically operates to supplement the manual driving of a normal driver, as described above, and that calculates and integrates various parameters related to the driving environment and driving state of the vehicle. This is a device that processes and improves the driving performance of vehicles from moment to moment. In FIG. 1, 10.12 indicates left and right front wheels configured as driven wheels, and 14.16 indicates left and right rear wheels configured as driving wheels. Left and right rear wheels 1
4 and 16, the output torque of the internal combustion engine 18 is transmitted to the transmission 20.
, the propeller shaft 22, the differential device 24, and the left and right axles 26 and 28.

A cylinder chamber (not shown) inside the internal combustion engine 18 takes in air through an intake passage 30 and a surge tank 32, is injected with fuel from a fuel injector 34, and is injected and supplied with the amount of intake air. The output is controlled by controlling the amount of fuel.

In the illustrated embodiment, the throttle opening is dynamically controlled by the electronic control device independently of the driver's willful depression of the accelerator pedal. A main throttle valve 36, which controls the amount of intake air according to the person's intention, is drivably connected to an accelerator pedal 38, and is provided to open and close according to the amount of depression of the accelerator pedal 38. A sub-throttle valve 42 is provided along and in series with the sub-throttle valve 42 whose opening and closing are controlled by an electronic control device. These may be replaced by a single throttle valve that is opened and closed by both the amount of depression of the accelerator pedal and the control operation of the electronic Ri controller, as described above.

The fuel injector 34 has its valve opening timing and valve opening period 114j controlled by a control signal from the fuel injection control device 40, and injects and supplies melon fuel to the cylinder chamber of the internal combustion engine 18 according to the valve opening time. There is. Fuel injection amount control by the fuel injection control device 40 is basically performed in accordance with the intake air amount.

The sub-throttle valve 42 is opened and closed by a step motor 44. The step motor 44 controls the opening degree of the sub-throttle valve 42 in response to a control signal from an electronic control device 46 for controlling automatic vehicle operation.

The electronic control device 46 may include a general microcomputer, and receives the rotation speed of the rear wheel drive system from the driving wheel speed sensor 48 as the driving wheel speed, and receives the rotation speed of the rear wheel drive system from the driving wheel speed sensor 48, and receives the rotation speed of the left and right driven wheels from the left and right driven wheel speed sensors 50 and 52. The rotation speed of the front wheels 10.12 is accepted as the vehicle speed of the left and right driving wheels, the information regarding the opening of the main throttle valve 36 is accepted from the throttle opening sensor 54, and the engine li is accepted from the engine rotation speed sensor 56.
'i1 accepting information about the number of rotations and determining whether the engine output should be urgently reduced according to these information;
If necessary, the fuel injection control device is operated to cut off the fuel supply, but before cutting off the fuel, the sub-throttle valve 42 is positioned in the manner described below with reference to FIG. A control signal (n11) is output to the step motor 44 to close the valve to the travel opening degree.

Next, referring to FIG. 2, an embodiment of the emergency fuel connection for emergency reduction of engine output and the control procedure for the 131 valve of the throttle valve 42 according to the present invention will be described. In this embodiment, the emergency reduction of the engine output occurs when the drive wheels slip beyond the set value with respect to the road surface, or when the vehicle speed becomes significantly excessive beyond the limit, the engine speed is reduced. This is done when the amount exceeds the allowable limit. Among these, control for emergency reduction of engine output, which is performed when the slippage of the drive wheels on the road surface exceeds a predetermined set value, is generally referred to as traction control.

First, in step 10, the flag Ft indicating that an emergency fuel cutoff for traction control has started is set to 1.
A determination is made as to whether this is the case.

When it is Ft-1, traction control has already been started, and at this time, the control process in the electronic control device proceeds to step 52, which will be described later. Otherwise, the control process proceeds to step 12.

In step 12, the driving wheel vehicle speed Vd detected by the driving wheel vehicle speed sensor 48 is determined from the left and right driven wheels 1. It is determined whether or not the value is greater than the sum of Vb and a predetermined amount a. When Vd>Vb10a, an acceleration slip occurs that requires traction control, and in this case, the flrlJ control process goes to steps 56 and 58, which will be described later, and the traction control routine and traction feedback control routine are executed. otherwise, the control process proceeds to step 14.

In step 14, it is determined whether a flag Fs indicating that control of the sub-throttle valve for reducing the intake air amount prior to emergency fuel connection has been started is 1 or not. When Fs-1, control of the sub-throttle valve has already started, and in this case, the control process proceeds to step 30; otherwise, the control process proceeds to step 16.

In step 16, on the ship, a determination is made as to whether the actual vehicle speed vb exceeds the limit W vehicle speed vh at which an emergency fuel cutoff should be performed, and if the answer is yes, the control process proceeds to step 26; otherwise, Sometimes the control process proceeds to step 18.

In step 18, a determination is made as to whether the engine speed Ne has exceeded the limit speed Nh at which emergency fuel measures should be taken, and if the answer is yes, the control process proceeds to step 26.
otherwise the control process proceeds to step 20
Proceed to.

In step 20, the driving wheel speed Vd is equal to the vehicle body speed Vb.
A determination is made as to whether or not the value is greater than the value obtained by adding a relatively small predetermined ff1b (b<a) to ff1b (b<a). When Vd≧vb+b, there is a possibility that acceleration slip will occur, in which case the control process proceeds to step 28; otherwise, 11. At +7, the control process proceeds to step 22.

In step 22, it is determined whether the rate of change (d/dL)em of the opening em of the main throttle valve 36 detected by the throttle opening sensor 54 is greater than a predetermined value 0m5et. (d/di) em≧e m5
If the condition is 3, it is a sudden acceleration situation where there is a risk of acceleration slip occurring, and in this case, the control process proceeds to step 28; otherwise, the control process proceeds to step 24.

Step 24 is performed when the vehicle speed is within a range that does not require emergency fuel disconnection, the engine speed is within a range that does not require emergency fuel disconnection, and there is almost no acceleration slippage and there is no risk of such occurrence. In this step, the control target opening degree est of the sub-throttle valve 42 is set to the maximum value ○s.
It is done to set it to max. As a result, the sub-throttle valve 42 is opened to the fully open position by the step motor 44.

Step 26 is a step in which a flag Fh is set to 1 when the vehicle speed or engine speed exceeds the respective set ratio W value requiring an emergency fuel cutoff.

Step 28 is a step in which when the occurrence of acceleration slip is predicted/Jll+, a flag Fs indicating this is set to 1. From step 28, the control process begins at step 30.
Proceed to.

4. In step 30, the sub-throttle control opening degree ess for urgently closing the sub-throttle valve is determined in accordance with the current operating state of the internal combustion engine 18, particularly the engine speed. Subthrottle control opening es
It is best to set s to the minimum valve opening for closing the sub-throttle valve without significantly reducing the output torque of the internal combustion engine, and this depends on the engine speed rather than the torque characteristics of the internal combustion engine. Therefore, the sub-throttle control opening degree ess may be set to a smaller value, that is, a larger opening degree, as the engine speed is lower, depending on the engine speed.

FIG. 3 is a graph showing the relationship between throttle opening and engine output torque for various engine speeds. Since an internal combustion engine generally has such a throttle opening χ・1 output torque characteristic of H, the subthrottle control opening ess, which closes the subthrottle valve prior to emergency fuel cutoff, is determined according to the engine speed as shown in Figure 4. It may be defined according to the characteristics as shown. This can be obtained by plotting the value of the throttle opening at the inflection point of the curve 5 for each engine speed in FIG. 3 against the value of the engine speed.

After step 30, in step 32, it is determined whether the sub-throttle control opening ess determined in step 30 is smaller than the sum of the small opening Δe that becomes the opening Om of the main throttle valve 36. A determination is made. If the answer is yes, proceed to step 34, set the ess calculated in step 30 to the target value of the subthrottle control opening of 61sL, and adjust the subthrottle valve to this value.
” Control is executed to close the opening to the standard opening. Also step 3
If the determination result in step 2 is NO, the control process proceeds to step 36, where Om+ΔO is set as the target value of the sub-throttle control opening, and the sub-throttle valve is adjusted so that the opening of the sub-throttle valve is set to this target value ○sL. Control is performed to close the . The sub-throttle control opening degree 61s determined based on the engine speed in step 30 in this way
Compare the size of s with the addition of a small opening ΔO, which is the opening of the main throttle valve at that time of 61 m, and find that ess is em + Δe.
The reason why em+Δe is used as the control opening target value of the sub-throttle valve when it is smaller is that when the opening of the sub-throttle valve is too large compared to the opening of the main throttle valve, the sub-throttle valve intended by the present invention is used. This is because no effect can be obtained.

Thus, after the control to close the sub-throttle valve is performed in step 34 or 36, the control process proceeds to step 38, where the count value Cs for taking the time is set.
is increased by 1. Among the control steps shown in FIG. 2, subroutine steps such as steps 48, 56, and 58, which will be explained below, are bypassed and the control process runs from the start to the return in one cycle of the control process. The time required is about ten milliseconds, and if this is, for example, 1611 sec, the count number Cs increases by 1 every 16 m5 ec.

In step 40 following step 38, It is determined whether the lag Fh is 1 or not.

If the answer is no, it means that the sub-throttle control performed in step 34 or 36 causes the driving wheels to slip or sit in excess of the set value relative to the road surface, or that the main throttle valve depression speed exceeds the predetermined value. This means that the need for I-traction control was predicted and the control to close the sub-throttle valve was performed because it was detected that the I'll constant viscosity was exceeded. This means that the subthrottle control performed in step 34 or 36 was performed as a preliminary control for fuel reduction due to the vehicle speed or engine speed increasing beyond their respective set values.

If the result of the determination in step 40 is no, the control process proceeds to step 42, where it is determined whether the count number Cs has reached a set value C5sct1 corresponding to the time of skiing for traction control. will be held.

If the answer is yes, the control process proceeds to step 44, and if the answer is no, the control process repeats itself. The count number C5set 1 is set to correspond to the maximum period during which the sub-throttle valve is closed in advance to reduce the intake air amount and the air pressure in the cylinder chamber is lowered in anticipation of a fuel cutoff for traction control. At the moment when it is detected in step 20 that a small slip corresponding to the vehicle speed has occurred, or in step 22, the main throttle valve opening speed is set to the set value elTl.
C5sct from the moment it is detected that it is higher than or equal to sot.
If the slippage of the drive wheels on the road surface further increases to a vehicle speed of 8 or more before the time corresponding to The process is step 12
, the control process then proceeds to step 56 where a traction control routine is executed in the manner described below, followed by a traction feedback control routine at step 58. .

9. The traction control routine 56 and traction feedback control routine may be as shown in Figures 5 and 6, respectively.

In the traction control routine shown in FIG. 5, the flag Fs is first reset to zero;
After t is set to 1, the traction control opening e stc for the sub-throttle valve is determined in order to further reduce the opening of the sub-throttle valve for traction control, and this e sac is set as the throttle control opening target value OsL. As a result, sub-throttle control is executed to control the opening degree of the sub-throttle valve, and fuel cut-off control is also executed. This fuel cutoff control is performed by the rate of change (
d/clt) Ne becomes equal to or less than a predetermined value N esct. In the embodiment shown in FIG. 2, the subsequent automatic control of engine power for traction control is in step 58!・This is done in the traction feedback control routine.

In other words, once the traction control routine is executed, the flag Ft is set to 0, so that the control process continues from step 1.
0, the process proceeds to step 52, where it is determined whether an arbitrarily set traction control termination condition is satisfied, and if the answer is no, the control process proceeds to step 5.
8, a traction feedback control routine is executed.

The traction feedback control routine may be as shown in FIG.
The integrated value is set as the control target vehicle speed Vt, and the difference between this control target vehicle speed Vt and the drive wheel vehicle speed Vd is set as the control deviation amount Dv,
Further, the difference in the rate of change between the vehicle body speed vb and the drive wheel speed Vd is defined as Dg, and the control target opening degree est of the sub-throttle valve is determined based on a predetermined function from Dv and Dg, and based on this target value. It performs subthrottle control. If it is determined in step 52 that the traction control termination condition is satisfied, the control process proceeds to step 54, where the flag Ft is reset to 0 and the subthrottle valve opening target value est is set to e smax. Then, the sub-throttle valve is fully opened.

On the other hand, the fact that the control process reaches step 46 means that an emergency fuel cut-off should be performed because the vehicle speed or engine speed exceeds the respective drop limit, and at this time, the count number Cs is the emergency fuel cutoff. The control process cycles through step 46 to return until Cs5ei2 is reached, which corresponds to the time required to reduce the air pressure in the cylinder chamber to a predetermined value prior to shutoff. When the count number Cs reaches Cs5ct2, the control process proceeds to step 48, where an emergency fuel cutoff is performed. The fuel cutoff control routine may consist of steps as shown in FIG. Set value vh or Nh
It is performed until it decreases by a predetermined value ΔV or ΔN consisting of,
When the vehicle speed or engine speed decreases by these predetermined values, the fuel 2 cutoff is terminated. After the fuel cutoff is completed, the control process proceeds to step 50, where the flag Fh is reset to 0, and the control process further proceeds to step 44, where the flag Fs and the count number Cs are also reset to 0.

In this embodiment, the closing time of the sub-throttle valve prior to the emergency fuel cut-off when the vehicle speed increases by 7:9 and the engine speed increases is the same time corresponding to Cs5cL2. These may be set separately by dividing flag Fh into two.

FIG. 8 is a graph showing an example of the time course of main throttle valve opening 0m1 sub-throttle valve opening os1 driving wheel vehicle speed Vd=vehicle speed Vb5 engine rotation speed Ne when traction control is performed. This figure also shows the progression of the temporal change rate (d/dt)em of the main throttle valve opening em, and the start of subthrottle control prior to fuel cutoff for traction control is (d/dt). It starts when the value of em exceeds the set value em5et, and from this point the count number Cs5e mentioned above is started.
It is designed to continue for a time t corresponding to L1. During this time, if it is not determined in step 12 that the slippage of the drive wheels with respect to the road surface has reached a value at which traction control should be performed by the traction control routine, the ZUB throttle valve is returned to the fully open position after the elapse of time t. .

In the example shown in FIG. 8, traction control is started by answering YES in step 12 during the process.

Although the present invention has been described in detail with respect to several embodiments above, it will be apparent to those skilled in the art that various modifications can be made to the illustrated embodiments without departing from the scope of the present invention.

[Brief explanation of drawings]

Fig. 1 is an illustrative plan view showing an example of a refusal vehicle incorporating an automatic operation control device that implements an emergency low range of engine output according to the present invention, and Fig. 2 is a method for emergency reduction of engine output according to the present invention. FIG. 3 is a graph showing changes in engine output torque with respect to throttle opening in an internal combustion engine at various engine speeds, and FIG. 4 is derived from the graph in FIG. 3. A graph showing the target value of the subthrottle control opening with respect to the engine speed, FIG. 5 is a flowchart showing an example of the traction control routine, FIG. 6 is a flowchart showing an example of the traction feedback control routine, and FIG. FIG. 8 is a flowchart showing an example of a fuel cutoff control routine performed when the rotational speed increases excessively, and FIG. 8 is a graph illustrating intermittent changes in various parameters in traction control. 10, 12... Driven wheel, 14, 16... Drive wheel, 1
8... Internal combustion engine, 20... Transmission device, 22... Propeller shaft, 24... Differential device, 26,
28... Axle 2 30... Intake passage, 32... Surge tank 34... Fuel injector, 36... Main throttle valve, 38... Accelerator pedal, 4
0... Fuel injection control device, 42... Sub-throttle valve, 44... Step motor, 46... Electronic control device, 48... Driving wheel vehicle speed sensor, 50, 52... Driven wheel vehicle speed sensor 5 vinegar. 54...Throittle opening sensor 5 6 ・ Engine rotation speed sensor Patent applicant Toyota Motor Corporation 'f1 Agent

Claims (1)

[Claims] A method for urgently reducing engine output in a vehicle equipped with an internal combustion engine in which the throttle opening is controlled by a combination of accelerator pedal depression and automatic control operation by an electronic control device. 1. A method characterized in that the fuel supply to the internal combustion engine is cut off, and the throttle opening degree is reduced by the electronic control device prior to the fuel cutoff.