JP2003239791A - Engine fuel supply control device - Google Patents

Abstract

[PROBLEMS] To provide a fuel supply control device for an engine that can avoid engine stall due to tire lock on a low friction road surface condition such as an ice burn or a low μ road under fuel cut control during deceleration. . SOLUTION: An accelerator opening detecting means 7 for detecting an opening of an accelerator pedal, an engine speed detecting means 8 for detecting an engine speed, and the accelerator pedal is in a fully closed state and the engine speed is lower. A deceleration fuel cut-off control means for executing fuel cut to the engine when the engine cutoff speed is equal to or more than a first predetermined value and prohibiting the fuel cut when the engine speed becomes equal to or lower than a second predetermined value. In the fuel supply control device, the road surface condition determining means 5b for determining the road surface condition is provided, and the deceleration-time fuel cut control means 5a determines that the road surface is in the low friction road surface condition by the road surface condition determining device 5b. A predetermined value changing means for changing the second predetermined value to a high value, and a low friction road surface condition such as an ice burn or a low μ road under deceleration fuel cut control. And so as to avoid the engine stall due to the tire lock.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an automobile engine.

[0002]

[Prior Art and Problems to be Solved by the Invention] Current A
T (Automatic Transmission) or CVT
(Continuous Variable Transmission)
In a vehicle equipped with a vehicle, when the vehicle is started, the vehicle is fixed at the second speed so that the engine torque rises more slowly than when the vehicle is started normally when the accelerator is operated (when the driver fixes the shift lever at the second speed or when the vehicle is mounted on the vehicle). Even when the snow mode is selected with the switch etc.), the engine speed for recovery (recovery) in deceleration fuel cut control is set to the same value as during normal start.

That is, the conventional fuel cut control during deceleration is
As shown in the flowchart of FIG. 3, when the fuel cut condition during deceleration is satisfied in step P1, it is determined in step P2 whether or not the engine speed exceeds a predetermined value (for example, 800 to 1000 rpm). The fuel cut is executed in step P3, and if not exceeded, the fuel cut is prohibited in step P4, and the predetermined value (for example, 800 to 1000 rpm) is always fixed.

Further, in a vehicle equipped with a torque converter with a lock-up clutch and an automatic transmission, a control for directly connecting the lock-up clutch during deceleration (deceleration direct connection control) is adopted in order to expand the operating range of fuel cut. is doing. In this deceleration direct connection control, the deceleration direct connection control is released and the direct connection is released when the engine speed falls below a set value in order to prevent engine stalling. However, in low friction road conditions such as ice burn or low μ road, the time until the tire locks during a sudden braking operation (during rapid deceleration) is extremely short, and the engine speed increases rapidly when the lockup clutch is directly connected. Since the engine speed drops below the set value and the lockup clutch is released from the direct connection, the direct connection cannot be released in time, and the engine speed continues to decrease rapidly. At this time, if the fuel cut control during deceleration is working, the engine speed will decrease more rapidly,
Even if the engine speed is below the predetermined value and the fuel cut is prohibited, the engine stall may occur if the return from the fuel cut is delayed.

Therefore, an object of the present invention is to provide an engine fuel supply control device capable of avoiding engine stall due to tire lock under a low friction road surface condition such as ice burn or low μ road under fuel cut control during deceleration. To provide.

[0006]

In order to achieve the above object, the invention according to claim 1 is an engine load detecting means for detecting an engine load, an engine speed detecting means for detecting an engine speed, and When the engine load is zero or minimum and the engine speed is equal to or higher than a first predetermined value, the fuel cut to the engine is executed, and when the engine speed is equal to or lower than a second predetermined value, the fuel cut is performed. A fuel supply control device for an engine, comprising: a fuel cut control means during deceleration for prohibiting the road surface state determination means for determining a road surface state, wherein the fuel cut control means during deceleration is determined by the road surface state determination means. Is determined to be a low friction road surface state, a predetermined value changing means for changing the second predetermined value to a high value is provided, and the fuel cut control during deceleration is performed. And so as to avoid an engine stall due to tire lock in the low friction road surface state such as Isuban or low μ road.

According to a second aspect of the present invention, the road surface condition judging means selects the middle speed starting shift mode or the snowy road shift mode by the shift mode setting means for setting the shift mode of the automatic transmission. If it is, the road surface is judged to be in a low friction road surface state, so in an AT or CVT mounted vehicle or the like, special road surface state determination means (road surface μ detection means, etc.)
Is unnecessary.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a fuel supply control apparatus for an engine according to the present invention will be described in detail with reference to the accompanying drawings with reference to the accompanying drawings.

[Embodiment] FIG. 1 is a block diagram of a fuel supply control apparatus for an engine showing an embodiment of the present invention, and FIG. 2 is a flow chart of fuel cut control during deceleration.

In FIG. 1, reference numeral 1 is an engine, 2 is a torque converter, and 3 is an AT (automatic transmission). Rotation of an output shaft (not shown) of the engine 1 is transmitted to the AT 3 via the torque converter 2 and from there, a predetermined value is transmitted. The gear ratio and the rotation direction are transmitted to the left and right drive wheels (not shown).

The engine 1 is provided with a fuel injection device 4, and the fuel injection device 4 includes the torque converter 2
The operation is controlled by an electronic control unit (ECU) 5 including a microcomputer and its peripheral circuits together with AT3.

The electronic control unit (ECU) 5 has deceleration fuel cut control means 5a and road surface condition determination means 5b. Further, the electronic control unit (ECU) 5 detects a vehicle speed detecting means 6 such as a vehicle speed sensor for detecting a vehicle speed, an accelerator opening detecting means 7 for detecting an opening of an accelerator pedal as an engine load, and an engine speed. The detection signals from the engine speed detecting means 8 such as an engine rotation sensor and the shift mode setting means 9 such as a shift lever and a mode switch are input. As the engine load detecting means, instead of the accelerator opening detecting means 7, a throttle valve opening detecting means for detecting the opening of the throttle valve may be used.

In the deceleration fuel cut control means 5a, the vehicle speed is detected by the vehicle speed detection means 6, the accelerator pedal is turned off by the accelerator opening detection means 7, that is, the engine load is zero or the minimum state, and the engine speed is reduced. When it is detected by the number detecting means 8 that the engine speed (Ne) is equal to or higher than a predetermined value (first predetermined value, for example, 2000 rpm),
When the deceleration fuel cut condition is satisfied, the fuel cut to the engine 1 is executed.

The road surface condition determining means 5b is controlled by the shift mode setting means 9 such as a switch mounted on the vehicle.
When it is detected that the medium-speed start mode such as fast start or the snow mode is selected, it is determined that the road surface is in a low friction road surface state.

The deceleration fuel cut control means 5
a is a return (recovery) engine speed (second predetermined value) that prohibits fuel cut to the engine when the road surface condition determination means 5b determines that the road surface is in a low friction road surface state, Predetermined value a (for example, 800 to 1000 rpm
) To a predetermined value b (for example, 1500 to 2000 rpm) to a high value (predetermined value changing means). It should be noted that the fuel cut control is controlled by parameters other than the engine speed (vehicle speed,
Even when the engine intake air amount is used, the second predetermined value may be similarly increased.

Further, in place of the road surface condition judging means 5b, a starting gear shift stage storing means 5 for storing a shifting gear stage at the time of starting.
c is provided in an electronic control unit (ECU) 5, and the fuel cut control means 5a for deceleration is a middle speed stage (2nd and 3rd speed) in which the speed is higher than the lowest speed (1st speed) by a hold switch or the like.
When the vehicle is started in the state of being fixed to the vehicle, the fact that the gear stage at the time of starting is the medium speed stage is indicated by the gear stage storage means 5 at the time of starting.
It is stored in c and it is determined that the road surface is in a low friction road surface state when the shift speed at start is the medium speed gear, and as described above, the return engine speed for prohibiting the fuel cut to the engine is changed to a high value. You may do it. In the case of CVT, it may be determined that the road surface is in a low friction state when the vehicle is started in a state where the gear ratio is fixed to a medium speed ratio higher than the minimum gear ratio (Low).

With such a configuration, the deceleration fuel cut control by the deceleration fuel cut control means 5a will be described below with reference to the flowchart of FIG. First,
When the fuel cut condition for deceleration described above is satisfied in step P1, it is determined in step P2 whether or not the road surface is a low friction road surface based on the information from the road surface state determination means 5b or the start gear position storage means 5c.

Next, if step P2 is affirmative, the engine speed is set to a predetermined value b (eg 1500 to 20) in step P3.
00 rpm) is exceeded. If it exceeds, the fuel cut is executed in step P4, and if it does not exceed, the fuel cut is prohibited in step P5.

On the other hand, if step P2 is negative, the engine speed is set to a predetermined value a (for example, 800 to 1000) in step P6.
rpm) is exceeded, and if so, fuel cut is executed in step P7, and if not exceeded, fuel cut is prohibited in step P8. After that, the same control operation is repeated.

As described above, in the present embodiment, when the vehicle is traveling on the low friction road surface state, the return engine speed (second predetermined value) under the fuel cut control during deceleration is set higher than that during normal vehicle traveling. Therefore, the fuel cut can be released from the region where the engine speed is higher than that during normal traveling, and the return from the fuel cut can be accelerated.

As a result, engine stall due to tire lock under a low friction road surface condition such as ice burn or low μ road under fuel cut control during deceleration can be avoided.

Needless to say, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist of the present invention. Further, the present invention is not limited to a vehicle equipped with an AT, but can be applied to a vehicle equipped with a manual transmission. In this case, the road surface μ detecting means 10 (see FIG. 1) for detecting the road surface μ may be provided as a means for determining the road surface state.

[0023]

As described above, according to the invention of claim 1, the engine load detecting means for detecting the engine load, the engine speed detecting means for detecting the engine speed, and the engine load being zero or When the engine speed is in the minimum state and the engine speed is equal to or higher than the first predetermined value, the fuel cut to the engine is executed, and when the engine speed is equal to or lower than the second predetermined value, the fuel cut is prohibited. A fuel supply control device for an engine, comprising: a cut control means; and a road surface condition determination means for determining a road surface condition, wherein the deceleration fuel cut control means determines that the road surface is in a low friction road surface condition by the road surface condition determination means. If it is determined that the predetermined value is changed, the predetermined value changing means for changing the second predetermined value to a higher value is provided. The engine stall due to tire lock in the low friction road surface condition of the low μ road or the like can be avoided in advance.

According to the second aspect of the present invention, the road surface condition determining means selects the medium-speed start shift mode or the snowy road shift mode by the shift mode setting means for setting the shift mode of the automatic transmission. If it is, it is determined that the road surface is in a low friction road surface state, so that a special road surface state determination means (road surface μ detection means, etc.) is not necessary in an AT or CVT mounted vehicle or the like.

[Brief description of drawings]

FIG. 1 is a block diagram of a fuel supply control device for an engine showing an embodiment of the present invention.

FIG. 2 is a flow chart of fuel cut control during deceleration.

FIG. 3 is a flowchart of conventional fuel cut control during deceleration.

[Explanation of symbols]

1 engine 2 Torque converter 3 AT 4 Fuel injection device 5 Electronic control unit 5a Fuel cut control means during deceleration 5b Road surface condition judging means 5c Gear shift storage means at start 6 Vehicle speed detection means 7 Accelerator opening detection means 8 Engine speed detection means 9 Shift mode setting means 10 Road surface μ detection means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 45/00 345 F02D 45/00 345G F term (reference) 3G084 BA13 CA06 CA08 DA17 DA34 EA11 FA05 FA06 FA10 FA18 FA33 3G093 AA05 BA01 BA05 CB05 CB07 CB08 DA01 DA06 DB05 DB11 EA05 FA11 3G301 JA31 JA38 KA16 KA26 KB01 KB10 MA11 MA24 NA08 PA11Z PA17Z PE01Z PF01Z PF03Z PF08Z

Claims (2)

[Claims] 1. An engine load detecting means for detecting an engine load, an engine speed detecting means for detecting an engine speed, the engine load being zero or a minimum state, and the engine speed being a first predetermined value. A fuel supply control device for an engine, comprising: a fuel cut control means for executing a fuel cut to the engine when the engine speed is equal to or more than a value, and for prohibiting the fuel cut when the engine speed becomes a second predetermined value or less. In the above, when the road surface condition determining means determines that the road surface is in a low friction road surface condition, the second predetermined condition is provided. An engine fuel supply control device comprising a predetermined value changing means for changing the value to a higher value. 2. The road surface condition determining means sets the road surface to a low friction road surface when the medium speed start gear shifting mode or the snow road gear shifting mode is selected by the gear shifting mode setting means for setting the gear shifting mode of the automatic transmission. The fuel supply control device for the engine according to claim 1, wherein the fuel supply control device is determined to be in a state.