JP2559953B2 - Engine fuel cut control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cut (fuel cut) control device for an engine, and more particularly to a fuel cut control device for an automatic vehicle.

[0002]

2. Description of the Related Art Generally, in this type of fuel cut control, fuel cut (fuel cut) is performed when the engine speed is high and the throttle valve is fully closed (idle) to improve fuel efficiency and unburned gas (monoxide). We are trying to prevent carbon emissions. However, conventionally, the engine speed at which the fuel cut is performed (fuel cut speed) is simply a function of only the engine water temperature, so that there is a problem that fuel efficiency cannot be sufficiently improved.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the fuel cut speed is a function obtained by adding the vehicle speed and the intake pipe pressure from the conventional function of only the water temperature. As a result, the fuel cut speed is reduced to the extent that engine stalling does not occur, and fuel efficiency is further improved.

That is, if the fuel cut speed is a function of the conventional water temperature only, there is no problem in normal running,
Automatic vehicle (AT vehicle) with a vehicle speed of 60km / h or more and an engine speed of 1 when driving overdrive.
It is in the range of 300 to 2000 rpm. In this state, downhill (for example, a loose and long downhill on a highway)
When downhill, etc., torque is not transmitted from the engine to the drive wheels, but torque is applied to the engine from the drive wheels. Therefore, during such a downhill, the fuel cut speed should be able to be made lower than when traveling on a flat road or climbing.

However, in this case, in a manual car or the like,
Since the engine and the drive wheels are directly connected by the clutch, if the road goes downhill to a flat road even a little, engine stall and drivability failure (for example, shock) may occur. The cutting speed cannot be lowered. However, since an automatic vehicle (AT vehicle) using an automatic transmission is driven by a torque converter, the above torque transmission relationship (between the drive wheel and the engine) is maintained even when the vehicle goes downhill to a flat road. Does not change rapidly (does not change rapidly).
Therefore, from the information on the vehicle speed and the intake pipe pressure, the state where the torque is transmitted from the drive wheel side to the engine side (that is, the downhill state described above) is detected, and in such a case, the fuel cut speed is set to the normal time. Even if the fuel is cut to a lower value and the fuel is cut aggressively (that is, even if the fuel is cut as it is and the descent is changed to a flat road as it is), there is no risk of engine stall or poor drivability.

Therefore, the present invention is based on such an idea.
In the case of an automatic vehicle, the above-mentioned downhill condition (that is, the state where torque is transmitted from the drive wheel side to the engine side) is judged from the information on the vehicle speed and the intake pipe pressure, and the downhill condition and the fuel cut are performed. When the condition is satisfied, the fuel cut speed is reduced to improve the fuel economy accordingly.

[0007]

According to the present invention, in order to solve such a problem, a vehicle is an automatic vehicle and a manual vehicle.
Means for detecting means for identifying whether it is Al vehicle, vehicle speed and the intake pipe pressure and, respectively, and the identified
When the vehicle is an automatic vehicle, when the detected vehicle speed is equal to or higher than a predetermined value and the intake pipe pressure is equal to or lower than the predetermined value, the fuel cut speed of the engine is reduced by a predetermined speed according to the vehicle speed and the intake pipe pressure. If you correct so that
If the identified vehicle is a manual vehicle,
There is provided a fuel cut control device for an engine, characterized in that it is provided with means for not performing positive .

[0008]

According to the above construction, the downhill condition (that is, the condition in which the torque is transmitted from the driving wheel side to the engine side) in the case of the automatic vehicle is detected from the information on the vehicle speed and the intake pipe pressure to perform the fuel cut. By reducing the rotation speed, it is possible to improve fuel efficiency. Also,
If the vehicle is a manual vehicle, the fuel cut speed
Since there is no correction to reduce the
However, it may worsen stalling and drivability.
Not.

[0009]

FIG. 1 shows a system configuration of a fuel cut control device as one embodiment of the present invention. An engine control computer CONT for performing the fuel cut control includes an engine speed and an idle switch. Signals such as on / off signals, engine water temperature, vehicle speed, and intake pipe pressure are captured. And the idle switch is on (idle state with throttle valve closed)
If the engine speed at that time is equal to or higher than the fuel cut speed, the fuel cut is executed. On the other hand, if the idle switch is turned off or the engine speed becomes lower than the fuel cut return speed after the fuel cut, the fuel cut is restarted. And in Figure 3,
This is an example of the value of the fuel cut return speed,
Normally, it is variable according to the engine water temperature (set to a lower value as the engine water temperature increases).

The fuel cut rotational speed is usually set to a value higher than the fuel cut return rotational speed by 600 rpm, for example. However, in the present invention, the fuel cut rotational speed is corrected (ie, corrected) when the following conditions are satisfied. Correction is performed so as to reduce the fuel cut rotation speed. That is, in the present invention, the fuel cut rotation speed is (fuel cut return rotation speed + 600 rpm +
When the following conditions are satisfied, a map value (for example, a negative value of about −100 to −400) shown in Table 1 below is set as the corrected rotation number. In other cases, the corrected rotational speed is set to zero as shown in Table 1.

[0011]

[Table 1]

That is, according to the present invention, in the case of an automatic vehicle (A / T vehicle), for example, an overdrive (4
Only in the high speed), the map value as shown in Table 1 is set as the corrected rotation speed. Here, Table 1 exemplifies a map for reducing the fuel cut rotational speed by a predetermined value (that is, the corrected rotational speed) when the vehicle speed and the intake pipe pressure at that time are in a specific range. so,
As shown in Table 1, for example, when the vehicle speed (unit is km / hour) is 60 km / hour or more and the intake pipe pressure PM (intake pipe absolute pressure) is 300 mmHg (absolute pressure value) or less. (That is, in the map shown in Table 1, when the vehicle speed and the intake pipe pressure are in the shaded area within the frame), depending on the vehicle speed and the intake pipe pressure PM at that time, Map values shown in Table 1 (unit is rpm)
Is taken in as the corrected rotational speed. In other words, the above-mentioned area within the frame (vehicle speed 60 km / h or more, intake pipe absolute pressure 300 mmHg or less (that is, the throttle opening is almost fully closed)
Area corresponds to the downhill state (that is, the state where torque is applied from the driving wheel side to the engine side), and in such a state, the corrected rotation speed indicated by the map value Only, the fuel cut rotation speed is reduced.

FIG. 2 is a flow chart exemplifying a processing procedure for the fuel cut control performed by the engine control computer shown in FIG.
In step 1, based on the engine water temperature at that time, the fuel cut return rotational speed as shown in FIG. 3 is calculated. Next, in step 2, it is determined whether or not the vehicle is an automatic vehicle, and in step 3, it is determined whether or not the vehicle is in the overdrive (4th speed) state. If both the determinations in step 2 and step 3 are YES, the process proceeds to step 4, and the intake pipe pressure P at that time is determined.
From M and the vehicle speed, the corrected rotation speed (that is, the map value shown in Table 1) is calculated. If the determination in step 2 or step 3 is NO, the corrected rotational speed is set to zero in step 5. After the value (zero or negative value) of the corrected rotation speed is determined in this way, the process proceeds to step 6 and the fuel cut rotation speed is set to the above step 1
600 rpm for the fuel cut return speed calculated in
Is added, and the value obtained by adding the corrected rotation number is set. In this way, when the vehicle speed and the intake pipe pressure PM are within the shaded area in Table 1, the fuel cut rotational speed is reduced by the corrected rotational speed.

Next, the routine proceeds to step 7, where it is judged if the idle switch (IDL) is turned on. If the result is yes, the routine proceeds to step 8 where it is judged if the fuel cut was made at the previous calculation timing. The determination is made based on the state of the X flag (the X flag is turned on if the cutting was previously performed). If the determination in step 8 is yes, the process proceeds to step 9 and the fuel cut return rotational speed calculated in step 1 is set in the register A. On the other hand, if the determination in step 8 is NO, the process proceeds to step 10 and the fuel cut speed calculated in step 6 is set in the register A. Then, in step 11, the engine speed at that time is the register A
It is determined whether or not the value is greater than or equal to the value set in. If the determination in step 11 is YES, it means that the engine speed is equal to or higher than the value set in the register A, so that the fuel cut is executed in step 12 and the X flag is turned on. To be in a state. On the other hand, if the determination in step 11 is NO,
Since this is the case where the engine speed is lower than the value set in the register A, the routine proceeds to step 13, where a return from the fuel cut is made and the above X
The flag is turned off.

[0015]

According to the present invention, when the automatic car is downhill, by fuel cut in the region of conventional fuel cut engine speed has not, fuel economy improved and unburnt (an It is possible to prevent the emission of carbon oxide). Also, the vehicle is a manual
For cars, correction to reduce the fuel cut speed
Is not done, so even if you go downhill to a flat road,
It does not deteriorate the driveability or drivability.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of a fuel cut control device as one embodiment of the present invention.

FIG. 2 is a flowchart illustrating a processing procedure performed by the engine control computer of FIG.

FIG. 3 is a diagram illustrating a relationship between a fuel cut return rotation speed and an engine water temperature.

Claims (1)

(57) [Claims] 1. A vehicle is an automatic vehicle or a manual vehicle.
Of the vehicle, the means for detecting the vehicle speed and the intake pipe pressure, and the vehicle identified as
When the vehicle is a tomatic vehicle, when the detected vehicle speed is equal to or higher than a predetermined value and the intake pipe pressure is equal to or lower than a predetermined value, the fuel cut speed of the engine is reduced by a predetermined speed according to the vehicle speed and the intake pipe pressure. is corrected to, the
If the identified car is a manual car, perform the correction.
A fuel cut control device for an engine, which is provided with a means which does not exist.