JPH10331673A - Fuel injection system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promptly cope with heavy gasoline by a simple means from setting of ordinary gasoline in a simple fuel injection system. SOLUTION: This system is provided with a throttle opening detection means 2, an air intake pressure detection means 1 in the downstream of a throttle and a back fire judgement circuit 5, and when throttle opening opens at more than a specified angle, the air intake pressure detection means 1 peak-outputs a value of more than atmospheric pressure and peak-output is detected several times, it is judged as back fire by heavy gasoline by the back fire judgement circuit 5. Consequently, an injector 4 is automatically actuated by a heavy gasoline used mode. Thereafter, the heavy gasoline used mode is released by detection output of an oil supply detection means 3 to a fuel tank. As it becomes proper injection quantity at the time of acceleration, etc., exhaust gas performance is improved by this system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION There are many types of gasoline used in automobiles, and the properties of each type of gasoline throughout the year are various. In recent years, due to environmental problems, due to the movement to reduce the amount of evaporative gasoline, the use of heavy gasoline for automobile gasoline in the summer has progressed, and there is a case where a simple fuel injection system with normal settings can not cope with various types of gasoline . For this reason, the present invention relates to a fuel injection system for an internal combustion engine that can immediately respond to heavy gasoline in a normal gasoline setting.

[0002]

2. Description of the Related Art Gasoline used in automobiles has been proposed to suppress the outflow of vaporized gasoline into the atmosphere due to environmental problems. For this reason, heavy gasoline is used in summer to suppress the volatility. Also, after the summer season, MTBE (octaneization improver) is positively mixed to improve volatility with MTBE, so that heavy gasoline can be used as it is. In addition, the fuel used differs depending on the region of use, not just the season. For example, hot spots (California, Arizona, etc.)
In summer, gasoline is very heavy, and in cold climates (Minnesota, Michigan, etc.) winter gasoline is light, and the fuel actually used varies widely from low to high volatility. They are used depending on the purpose.

Here, an example of an automobile engine for an automobile fuel will be described. As shown in FIG. 4, the single-point engine (hereinafter, referred to as SPI) has an injector 2 provided on an inlet side 1 a of a throttle body 1, and a throttle device 3 has a position sensor ( TPS) 5 and a drive motor 6, and a heater 7 is provided on the outlet side 1 b of the throttle body 1.
And a temperature sensor 8. An O ₂ sensor 10 and a catalyst 11 are provided on the exhaust side of the engine body 9.
Is provided.

The fuel in the fuel tank 12 is sent to the injector 2 when the pump relay 13 operates and the fuel supply pump 14 operates. The opening and closing of the cap 15 of the fuel tank 12 is monitored by a control module 16. Further, the operation of the throttle relay 17 operates the drive motor 6 to adjust the throttle opening. In addition, reference numeral 18 is an ignition coil, 19 a battery, 20 is the O ₂ sensor relay 21 is heater relay.

In the above-described SPI engine, the fuel supplied to the engine body 9 is synchronously injected from a single injector 2 with respect to an ignition signal, in other words, an injection pulse is generated for each ignition signal to inject the fuel. . Then, during the acceleration, asynchronous temporary injection is performed to increase the injection amount,
During deceleration, fuel cut is performed by intermittent injection. In this case, the fuel injected from the injector 2 is sucked into the engine body 9 through the intake manifold 22 in the throttle body 1, so that the passage length is easily affected by the vaporization difference of the fuel gasoline.

[0006] That is, when running with heavy gasoline as it is with the specifications that match the starting system and the acceleration system with normal gasoline, fuel response to the combustion chamber during transient (acceleration) delays, so that hesitation and back Fire and stalling due to the fire easily occur. For this reason, in the specifications for heavy gasoline, including the region where heavy gasoline is used, the setting of a richer eye than the stoichiometric setting such as increased acceleration and increased warm-up is required.

[0007]

By the way, even with heavy gasoline mixed with MTBE, when a car is left for a long time under the scorching sun or the like, only MTBE having high volatility evaporates preferentially. Will be forced to run on heavy gasoline and the settings will be adjusted again. Also, if a gasoline property sensor is separately installed so that heavy gasoline is judged before driving the engine, and a system that corrects the control of the starting system and acceleration system when using heavy gasoline is installed, it will be very expensive. Therefore, the installation cost is too high for SPI which is an inexpensive system, and the cost is low.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection system for an internal combustion engine in which heavy gasoline is determined by simple means, and after the determination, the engine is automatically driven with the setting for heavy gasoline. And

[0009]

In order to achieve the above object, according to the present invention, a throttle opening detecting means, an intake pressure detecting means downstream of the throttle,
A fuel tank refueling detecting means, and when a backfire is determined based on outputs of the throttle opening degree detecting means and the intake pressure detecting means, at least one of an injector and a throttle is operated in a heavy gasoline use mode to refuel. The heavy gasoline use mode is canceled by the output of the detection means.

According to a second aspect of the present invention, in the first aspect of the present invention, when the throttle opening is opened to a predetermined angle or more and the intake pressure detecting means outputs a peak value equal to or more than the atmospheric pressure, it is determined to be backfire. It is characterized by doing.

With the above-described configuration, the characteristic of the backfire is detected by the intake pressure detecting means and the throttle opening detecting means to determine heavy gasoline, and after the determination, the heavy gasoline use mode is automatically set. Start the engine.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Air-fuel ratio (A
/ F) is usually matched with gasoline, and when accelerating, backfire may frequently occur due to lean mixture. This indicates that when the accelerator opening is increased as shown in FIG. 3A, a peak value (peak value) of the intake pressure is generated as shown in FIG. 3B. Also,
When heavy gasoline is used, fuel supply delay during transient (acceleration) occurs due to poor volatility, and the mixture becomes lean,
Backfire has occurred. Therefore, the present invention employs a determination system that distinguishes backfire when it occurs and regards it as using heavy gasoline.

As shown in FIG. 1, among fuel injection systems having an injector, a throttle, and the like, a heavy gasoline determination system includes an intake pressure detection unit (MAPS), a throttle opening detection unit (TPS), and a refueling detection unit. And these are E. coli. C. M. (Control module)
The refueling pump or the drive motor is controlled so as to operate at least one of the injector (fuel supply means) and the throttle. The intake pressure detecting means uses a MAP sensor for detecting the intake pipe internal pressure, and the throttle opening detecting means uses a throttle position sensor (TPS).

E. C. M. Then, the intake pressure detecting means (MA
PS) and the output of the throttle opening detection means (TPS) are input to a backfire determination circuit, and are sampled and stored by a clock circuit and a memory circuit. This data is input to the fuel supply amount setting circuit and is compared with the current output of MAPS and TPS. When it is determined that heavy gasoline is used, the correction amount is added to the basic amount, and the refueling pump and the injector operate. Further, in this state, the heavy gasoline use mode is canceled at the time of refueling by refueling detection means (for example, checking opening and closing of the cap of the fuel tank).

Next, determination of backfire will be described with reference to the flowchart of FIG. First, the ignition is turned on, and PM (intake pipe pressure) is measured by MAPS. The initial input value at the time of starting is PMA (atmospheric pressure). Next, it is determined whether the PM has changed significantly beyond the PMA. That is, when a backfire occurs, the PM instantaneously jumps above the PMA. Other than this, it is unlikely that PM becomes higher than PMA during running. C. M. The (backfire determination circuit) detects this. At this time, the throttle opening T
It is checked whether or not A is equal to or greater than the predetermined opening degree, and if the confirmation item is Yes, it is determined whether or not this change has been made continuously. This can be distinguished from a normal gasoline backfire. When the determination of the continuous detection is Yes, it is determined that the backfire comes from heavy gasoline.

The change in the intake pipe pressure PM means that the difference between PMA and PM fluctuates from 50 mmHg or more to 50 mmHg or less, and when the throttle opening TA is 80 or more at the time of the fluctuation, this change is 2 within 2 seconds
When PM> PMA is detected more than once, it is determined that the backfire comes from heavy gasoline.

Immediately after the backfire determines that heavy gasoline is being used, the asynchronous injection and the acceleration increase value are increased. Further, the backfire determination is always started during the operation of the engine, and once the Yes determination is made, the Yes determination is retained regardless of the stoppage of the engine thereafter. The fuel supply amount increase correction is further increased compared to the non-Yes determination. That is, as shown in FIGS. 3C and 3D, when the air-fuel ratio is increased while the amount of the asynchronous injection and the acceleration increase correction performed at the time of normal acceleration using heavy gasoline is not changed, backfire tends to occur. According to the determination that heavy gasoline is being used, the acceleration increase correction is performed as shown by e and f in FIG. 3 to stabilize the combustion conditions.

Since the above correction is determined by what kind of fuel is currently in the fuel tank, this correction is effective until the next refueling, and is reset at the next refueling (normal gasoline use). Mode)
Things. The measurement result of the atmospheric pressure by the MAPS is valid until the engine is stopped, and is updated every time the engine is started. When the Yes determination that heavy gasoline is used is released, it is a time of refueling determination. For example, the opening of the lid is detected by a switch provided at the refueling port, and ON / OFF of the lid may be performed. The opening may be detected by a switch provided on an opener (lever) for opening the valve, or may be detected by an output of a level detecting means in the fuel tank (such as an output due to a large increase). In this way, the heavy gasoline determination system has a simple configuration and can be installed at low cost.

[0019]

The present invention is constructed as described above. In the fuel injection system, in order to provide an engine that can respond to heavy gasoline, the intake pressure detecting means and the throttle opening degree detecting means are used to control the backfire. Since the characteristic is determined to be heavy gasoline, the system configuration can be simplified without using a special sensor or the like, and it can be reliably determined that heavy gasoline is being used. After judging that heavy gasoline is being used, the engine is automatically driven with the settings for heavy gasoline, so it is possible to avoid known problems when using heavy gasoline, Matching with gasoline in mind is performed automatically, and an appropriate injection amount is obtained during acceleration or the like, thereby improving exhaust gas performance. In addition, since the heavy gasoline use mode is canceled by the output of the refueling detection means for each refueling, there is no need to manually reset.

[Brief description of the drawings]

FIG. 1 is a block diagram of a fuel injection system for an internal combustion engine according to the present invention.

FIG. 2 is a flowchart of a determination unit of the fuel injection system shown in FIG.

FIG. 3 is a graph illustrating the fuel injection system shown in FIG.

FIG. 4 is a configuration diagram of a conventional fuel injection system for an internal combustion engine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 intake pressure detecting means (MAPS) 2 throttle opening detecting means (TPS) 3 refueling detecting means 5 backfire determination circuit

Claims (2)

[Claims] 1. A throttle opening detecting means, an intake pressure detecting means downstream of a throttle, and a fuel supply detecting means to a fuel tank are provided, and a backfire is determined by an output of the throttle opening detecting means and the intake pressure detecting means. A fuel injection system for an internal combustion engine, wherein at least one of the injector and the throttle is operated in a heavy gasoline use mode, and the heavy gasoline use mode is released by an output of a refueling detection means. 2. Opening the throttle opening at a predetermined angle or more,
2. The fuel injection system for an internal combustion engine according to claim 1, wherein a backfire is determined when the intake pressure detecting means outputs a peak value equal to or higher than the atmospheric pressure.