JPH09287512A - Detecting method for descending slope traveling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make descending slope traveling possible without using a grade sensor by detecting the total quantity within a prescribed time of fuel supplied during traveling on an about flat road as a fuel quantity during descending slope traveling in the case where the actual fuel supply quantity satisfies prescribed conditions to a reference total supply quantity computed at least on a vehicle speed. SOLUTION: An electronic controller 6 determines a basic injection time on each of output signals sent from a throttle sensor 16 and a cam position sensor 14, and the basic injection time is usually corrected by feedback-control on an output signal (h) sent from a O2 sensor to determine effective injection time. In addition, the total quantity within a prescribed time of fuel supplied to an engine 100 during traveling on an about flat road is computed as the reference total supply quantity at least based on a vehicle speed, and the total quantity of fuel actually supplied within a prescribed time is computed as the total actual supply quantity. As result of the reduction of reference integrated value from actual integrated value, the traveling is judged as the descending slope traveling in the case where the actual integrated value is less than the reference integrated value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a downhill traveling detection method for controlling a fuel injection control type internal combustion engine for an automobile.

[0002]

2. Description of the Related Art Conventionally, there is known an internal combustion engine which employs a fuel injection system called a so-called α-N system which determines a fuel injection amount based on a throttle opening and an engine speed. In a vehicle equipped with such an internal combustion engine, after learning the air-fuel ratio at high altitude, if you change to flatland running with continuous fuel cut without almost pressing the accelerator pedal, you can learn while traveling downhill. Failure to do so may cause problems in flatland traveling.
In order to solve this problem, even when traveling downhill, the air-fuel ratio is learned so that the vehicle can travel without hindrance when returning from a high altitude where the atmospheric pressure is low to a flat ground.
In order to learn the air-fuel ratio during such downhill traveling, it is known to detect downhill traveling and learn the air-fuel ratio by a method different from the usual method at that time. As the downhill traveling, for example, as described in Japanese Patent Laid-Open No. 58-214643, the inclination of the vehicle in the front-rear direction is detected by a gradient sensor.

[0003]

However, in the above, a gradient sensor which is a dedicated sensor is required only for detecting downhill traveling. In other words, in addition to the standard sensors such as the revolution speed sensor, throttle sensor, vehicle speed sensor, and shift position switch that are usually equipped to control the air-fuel ratio of the engine, it is necessary to equip a gradient sensor that is rarely used. Comes out. In addition to such a gradient sensor, in a vehicle equipped with an automatic transmission, it is used to determine whether acceleration or deceleration is being performed based on the ratio of the engine speed to the rotation speed of the torque converter of the automatic transmission. Therefore, a rotation sensor for a torque converter, a torque sensor, etc. are required. In such a case, as a result, the manufacturing cost is increased by the cost of the dedicated sensor for detecting the downhill traveling.

An object of the present invention is to solve such a problem.

[0005]

The present invention takes the following means in order to achieve such an object. That is, in the method for detecting downhill traveling according to the present invention, attention is paid to the fact that the work of the fuel injection type internal combustion engine is determined by the intake air amount, and the supply of fuel in the reference traveling state that is correlated with this intake air amount. Calculates the total amount based on at least the vehicle speed, compares the calculation result with the total supply amount in the actual traveling state, and detects the downhill traveling when the total supply amount in the actual traveling state meets the conditions for the reference traveling state To do.

With such a structure, it is not necessary to add a dedicated sensor such as a gradient sensor. That is, since the signal from the sensor necessary for performing the fuel injection control in the fuel injection type internal combustion engine can be shared, it is possible to detect the downhill traveling without increasing the cost due to the addition of the sensor or the like. .

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention calculates the total amount of fuel supplied to a fuel injection type internal combustion engine mounted on a vehicle during traveling on a substantially flat road within a predetermined time as a reference total supply amount based on at least the vehicle speed. Then, the total amount of fuel actually supplied within the predetermined time is calculated as the actual total supply amount, and when the actual total supply amount satisfies the predetermined condition with respect to the reference total supply amount, it is detected that the vehicle is traveling downhill.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. An engine 100 schematically shown in FIG. 1 is mounted on an automobile, and an intake system 1 thereof is provided with a throttle valve 2 which opens and closes in response to an accelerator pedal (not shown), and a surge tank is provided downstream thereof. 3 is provided. A fuel injection valve 5 is further provided near one end of the intake manifold 4 of the intake system 1 communicating with the surge tank 3, and the fuel injection valve 5 is controlled by the electronic control unit 6. . In addition, an O ₂ sensor 21 for measuring the oxygen concentration in the exhaust gas is attached to the exhaust system 20 at a position upstream of a three-way catalyst 22 arranged in a pipe line leading to a muffler (not shown). There is. This O ₂ sensor 21 outputs an output signal h corresponding to the oxygen concentration.

The electronic control unit 6 includes a central processing unit 7
, A storage device 8, an input interface 9, and an output interface 11. The storage device 8 is provided with a RAM area in which a start position opening degree TAO described later is temporarily stored. Input interface 9
Is a cam for detecting a shift position signal a output from a shift position switch 13 for detecting a gear position of a transmission (not shown), an engine speed NE, a cylinder discrimination, and a crank angle reference position. Rotation speed signal N output from the position sensor 14
e, a cylinder discrimination signal G1, a crank angle reference position signal G2, a vehicle speed signal c output from a vehicle speed sensor 15 for detecting a vehicle speed, and a vehicle speed signal 16 output from a throttle sensor 16 for detecting the opening of the throttle valve 2. The throttle opening signal d, the water temperature signal e output from the water temperature sensor 17 for detecting the cooling water temperature of the engine 100, the output signal h output from the O ₂ sensor 21 and the like are input. On the other hand, the output interface 11 outputs a fuel injection signal f to the fuel injection valve 5 and the spark plug 1
Ignition pulse g is output to eight.

The electronic control unit 6 includes a throttle sensor 1
The basic injection time TP is determined based on the throttle opening signal d output from 6 and the rotation speed signal Ne output from the cam position sensor 14 as main information, and in the steady state, the output signal h from the O ₂ sensor 21 is determined. A program is incorporated to correct the basic injection time TP based on the feedback control to determine the effective injection time TAU, and to inject the fuel in synchronization with the ignition timing based on the determined effective injection time TAU. In addition, the electronic control unit 6 determines that the engine 10 should be run on a substantially flat road in order to determine whether the vehicle is going downhill.
The total amount of fuel supplied to 0 within a predetermined time is calculated as a reference total supply amount based on at least the vehicle speed, the total amount of fuel actually supplied within a predetermined time is calculated as an actual total supply amount, and the actual total supply amount is a reference value. A program for detecting that the vehicle is traveling downhill when a predetermined condition is satisfied with respect to the total supply amount is incorporated.

The outline of the downhill traveling determination program is as shown in FIG. In FIG. 2, first, in step S1, a reference effective injection time TAUREF corresponding to a fuel injection amount required for traveling on a substantially flat road from the vehicle speed and the gear position detected by the vehicle speed signal c and the shift position signal a is calculated. . That is, the reference effective injection time TAUREF is calculated by estimating the intake air amount and the engine speed NE as the effective injection time required when traveling on a substantially flat road with the combination of the detected vehicle speed and the gear position. To do. This is the engine 10
It is focused on that the work amount of 0 is determined by the intake air amount, and the work amount is estimated by integrating the effective injection time correlated with the intake air amount. In step S2, the actual effective injection time TAU is calculated.
In step S3, the reference integrated value TTAUREF _n , which is the total supply amount of the reference effective injection time TAUREF, is calculated by the following equation. That is, the reference integrated value TTAURE of this time
F _n is for calculating by adding the reference integrated value TTAURFE _n-1 to the current operation criteria effective injection time TAUREF _n up to the previous. TTAUREF _n = TTAUREF _n-1 + TAUREF _n

In step S4, the actual effective injection time T
The actual integrated value TTAU which is the total supply amount of AU is calculated by the same method as the case of the reference integrated value TTAUREF. TTAU _n = TTAU _n-1 + TAU _{n In} step S5, it is determined whether the elapsed time Tl from the start of the downhill traveling determination operation exceeds the predetermined time α. The predetermined time α is set to about 3 minutes, for example. This is for detecting the downhill traveling in which there is a difference in altitude at least between the start time and the end time of the downhill traveling determination, and is not limited to this numerical value. In step S6, the actual integrated value TTAU is changed to the reference integrated value TTAU.
REF is subtracted, and it is determined whether the result exceeds a predetermined value β. The predetermined value β is, for example, 0, and when the actual integrated value TTAU is equal to or less than the reference integrated value TTAUREF, it is determined that the vehicle is traveling downhill. By setting this predetermined value β to a value other than 0 described above, for example, a small value of +, it is possible to change the determination standard, and the determination standard can be made relatively gentle, and the actual integration Value T
Even when TAU exceeds the reference integrated value TTAUREF, it is determined that the vehicle is traveling downhill. on the other hand,
Conversely, by setting the predetermined value β to a negative value,
It is also possible to make the judgment severe. In step S7, it is determined that the vehicle is not traveling downhill, and the downhill traveling determination flag is reset. In step S8, the actual integrated value TTA
Clear U and the reference integrated value TTAUREF. In step S9, the time counter for counting the elapsed time Tl is incremented. In step S10, it is determined that the vehicle is traveling downhill, and the downhill traveling determination flag is set.

In such a configuration, as shown in FIG. 3, when the running state is in a general running state including acceleration and deceleration, which changes variously from the steady state within a predetermined time α,
Until the predetermined time α is reached, the control is repeatedly executed from step S1 to step S5 → S9 to obtain the actual integrated value TTAU.
And the reference integrated value TTAUREF are calculated. In such a traveling state, in addition to traveling in the steady state, acceleration and rapid acceleration are performed, and therefore the effective injection time TAU is increased and corrected during the transition as compared with the steady traveling state. ,
Is increasing. Therefore, as shown in FIG. 3, the actual integrated value TTAU exceeds the value obtained by adding the predetermined value β to the reference integrated value TTAUREF. And the elapsed time T
When l exceeds the predetermined time α, the control proceeds from step S5 to steps S6 → S7 → S8, resets the downhill traveling determination flag because the vehicle is not traveling downhill, and starts the next downhill traveling determination.

On the other hand, when the vehicle travels to a high altitude and returns almost without pressing the accelerator pedal, that is, when the vehicle travels downhill with the throttle valve 2 almost fully closed,
Until the elapsed time Tl exceeds the predetermined time α, the control is performed in the same manner as in the general running, from step S1 to step S5 → S9
Is repeatedly executed. In the case of such a relatively long downhill run without uphill in the middle, for example, the accelerator pedal may be slightly operated around a curve, but the throttle valve 2 is opened as a whole. Never. Therefore, the fuel amount is hardly corrected while the fuel is being cut or only when the transient amount is slightly increased. Therefore, the actual integrated value TTAU does not exceed the reference integrated value TTAUREF. That is, FIG.
As shown in, the actual integrated value TTAU is equal to the reference integrated value TTA.
It is much less than UREF, and does not exceed the reference integrated value TTAUREF, which is the determination standard, beyond the predetermined value β. As a result, the control proceeds to step S6 → S10 → S8 after the elapsed time Tl exceeds the predetermined time α,
The downhill traveling determination flag is set to detect that the vehicle is traveling downhill.

In this way, the downhill traveling is determined at every predetermined time α, and the downhill traveling determination flag which is once set or reset holds the state until the next determination result is obtained. . This downhill traveling determination flag is used, for example, when performing learning control of the air-fuel ratio during traveling downhill. Further, in a vehicle equipped with an automatic transmission, it may be used for control for changing the shift position of the automatic transmission in order to apply the engine brake during such downhill traveling. As described above, since it is not necessary to add a dedicated sensor or the like to determine the downhill traveling, it is possible to detect that the vehicle is traveling downhill without increasing the manufacturing cost.

The present invention is not limited to the embodiment described above. In the above embodiment, the effective injection time TAU is calculated based on the engine speed NE and the throttle opening. However, the effective injection time TAU is calculated based on the engine speed NE and the intake pipe pressure or the intake air amount. It may be applied to a method of calculating TAU.

In addition, the configuration of each section is not limited to the illustrated example, and various modifications can be made without departing from the spirit of the present invention.

[0018]

As described above, according to the present invention, it is not necessary to provide a dedicated sensor for detecting the downhill traveling, and the downhill traveling can be detected inexpensively without increasing the manufacturing cost. You can Further, the detection standard for downhill traveling can be changed by changing the predetermined condition for the actual total supply amount with respect to the reference total supply amount.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory view showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of the embodiment.

FIG. 3 is an operation explanatory view of the same embodiment.

FIG. 4 is an operation explanatory view of the embodiment.

[Explanation of symbols]

 2 ... Throttle valve 5 ... Fuel injection valve 6 ... Electronic control device 7 ... Central processing unit 8 ... Memory device 9 ... Input interface 11 ... Output interface 16 ... Throttle sensor

Claims (1)

[Claims] 1. A total amount of fuel supplied to a fuel injection type internal combustion engine mounted on a vehicle during traveling on a substantially flat road within a predetermined time is calculated as a reference total supply amount based on at least a vehicle speed, and within a predetermined time. A downhill characterized by calculating the total amount of fuel actually supplied as the actual total supply amount and detecting that the vehicle is traveling downhill if the actual total supply amount satisfies a predetermined condition with respect to the reference total supply amount. How to detect running.