JPS60216041A - Fuel-cut apparatus for car engine - Google Patents

Abstract

PURPOSE:To spread the fuel-cut range without deteriorating drivability by memorizing a road-load curve into a microcomputer. CONSTITUTION:A fuel-cut means or electromagnetic fuel-cut valves 6 and 7 are installed into fuel passages 3 and 4, and the opening and closing of said valves are controlled by a microcomputer 8. A road load curve or the curve approximate to the road-load curve is memorized into the microcomputer 8. When a car-speed sensor 13 detects the car-speed, and the actual engine load at that car speed is on the light-load side in comparison with the above-described curve, fuel-cut is carried-out. Therefore, a fuel-cut range can be spread without deteriorating the drivability.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a fuel cut device used primarily in automobiles during deceleration.

(b) Conventional technology: When the accelerator pedal is released and the vehicle is decelerated by so-called engine braking, the load in the intake pipe increases rapidly and a large amount of fuel 4 is sucked out from the slow system or main system fuel passage. The concentration of harmful components such as HC in the exhaust gas increases, and
This tends to lead to the inconvenience of deteriorating fuel economy. Also,
There is also the problem that unburned gas is led to the exhaust system and causes heating of the catalyst.

Therefore, in recent automobiles, a fuel cut pulp is interposed in the fuel passage described above, and when the vehicle enters a deceleration mode due to engine braking, the 2-needle cut valve is switched to the closed position and the fuel passage is (In this specification, "blocking" means not only a state that completely blocks the passage of fuel, but also an incompletely closed state that allows the passage of a small amount of fuel.) Many of them are equipped with cutting devices.

As a prior art related to such a fuel cut device, as shown in Japanese Patent Application Laid-Open No. 56-537-g-, a fuel cut valve is provided in the fuel passage to cut off the passage, and the transmission seal is connected to the fuel passage. is not neutral, top or overtop] -
When the clutch is in the connected state, the +lt speed is equal to or higher than the set speed, and the engine load detected by the throttle opening or boost pressure is less than the set value, the fuel cant valve is filled with fuel. There is one in which the signal 41'f is set to shut off the n11 fuel passage. However, simply using this alone has the problem that the effect of improving fuel economy is insufficient, and it is also difficult to sufficiently suppress the heating of the catalyst.

The inventor of the present invention conducted research to find out the cause of this problem, and as a result, the following facts were discovered. In other words, the engine load when a car runs steadily on a horizontal flat road when there is no wind varies depending on the vehicle speed, and its value is determined by the road load curve (Road-Load curve) shown by the solid line A in Figure 1.
curve). However, when both Φ cars continue to run under a lighter load than the road load curve, they are running with engine braking applied to varying degrees, and in this case, the supply of electricity to the engine A large shock felt by the human body even if the fuel is cut (IF speed change)
On the other hand, when the vehicle is running at a higher load than the road load curve, the vehicle is traveling uphill or against a headwind with the help of the engine, and this In such cases, cutting the fuel will cause a large shock to the vehicle, worsening drivability.

However, in the conventional engine, the fuel is cut based on a constant engine load as shown by the imaginary line B in FIG. 1, regardless of the road load curve. Therefore, if the setting value for the engine load is set on the vacuum side, the fuel car/h region will become narrower and the fuel economy will deteriorate.On the other hand, if it is set on the atmospheric pressure side, the setting value will be lower than the 16 road load curve mentioned above. Fuel cut may occur on the high load side, significantly deteriorating drivability. Therefore, the conventional type has a problem in that it is difficult to significantly improve fuel economy or effectively prevent catalyst heating without deteriorating drivability.

(c) Purpose The present invention has been made with attention to the eastern situation,
3I! A vehicle engine that can expand the fuel cant area without causing deterioration of convertibility, reasonably improve fuel economy, and effectively prevent catalyst heating. The purpose of IJ is to provide a fuel cut device.

(D) Structure In order to achieve the above object, the above-mentioned road load curve or a curve approximating this curve is stored in the storage device 4, and this curve corresponds to the vehicle speed during actual driving. The present invention is characterized in that a comparison calculation is made between the actual engine load and the fuel cut when the actual engine load at the vehicle speed is on the lighter load side than the curve.

(E) Example An example of the present invention will be described below with reference to FIGS. 2 to 4.

FIG. 2 is a system explanatory diagram of the fuel cut device according to the present invention, in which 1 is a carburetor of an automobile engine;
2 is the slow/) rev of this carburetor↓, 3 is the slow system fuel passage, 4 is the main system fuel passage, and 5 is the float chamber. An electromagnetic fuel cut valve 6.7 as a fuel cut means is provided in each of the fuel passages 3.4, and the opening and closing of each fuel cut valve 6 is controlled by a computer 8. This is a normal system in which a central processing unit 9, a storage device 10, and interfaces 11 and 12 are co-located, and signals from a vehicle speed sensor 13 and an engine load detector 14 are input to the interface 11, respectively. Further, the interface 12 outputs a fuel cut signal or a fuel cut signal to the fuel car/top valve 6.7. The engine load detector 14 includes, for example, a diaphragm mechanism 15 that converts intake pipe negative pressure downstream of the throttle valve 2 into mechanical displacement, and an electrical analog signal that converts the mechanical output of the diaphragm mechanism 15 into mechanical displacement. It is equipped with a potentiometer 16 that converts the output from the potentiometer 16 into a digital signal, and an A/D converter 17 that converts the output from the potentiometer 16 into a digital signal. Then, in the storage device 10 of the computer 8,
Information regarding a curve d that approximates the road load curves a, b, and c is stored. Specifically, first, the transmission is set to third gear and the vehicle is driven at a constant speed on a flat road, and when the fuel to the carburetor is cut off, the speed change rate of the vehicle exceeds a predetermined value. Find out the limit point of carrot load (intake pipe negative pressure). Here, the predetermined value is a value determined based on whether or not a person riding in the vehicle feels a shock when the fuel is cut off. Then, by measuring this limit point while changing the vehicle speed to a plurality of stages, a road load curve a in third speed is obtained.

A similar investigation was also conducted when the transmission was set to 4th and 5th speeds, and the road load surface and 9. Obtain the road load curve C in b and 5th gear. Afterwards, these road load curves a,
A curve d that approximates b and c is determined 1, and this curve d is converted into mathematical formulas and other information and stored in the storage device 10. The microcomputer 8 then compares and calculates this curve d with the actual engine load corresponding to the vehicle speed during actual driving, and calculates whether the actual engine load at that vehicle speed is on the lighter side than the surface &l1jd. There is a built-in program that can output a fuel cut signal to the fuel cut valve 6.7 when the fuel cut valve 6.7 is present. The contents of this program will be specifically explained below with reference to the flowchart shown in FIG. First, the vehicle speed sensor 13 and the engine load detector 14
, that is, a signal indicating the vehicle speed and the intake pipe negative pressure, and the intake pipe negative pressure corresponding to the vehicle speed is in the fuel cut possible region, that is, the above curve d.
1 in the figure. If it is determined that it is in that area, move to step (a),
In other cases, the process moves to step (B). When proceeding to step (a), it is determined whether the fuel car is in the process of being cut or not, and if the fuel is not being cut, a fuel cut signal is output, and if the fuel is being cut, that state is maintained. On the other hand, when moving to step (b), it is determined whether or not the fuel is being cut,
When the fuel is being cut, a fuel cut release signal is output, and when the fuel is not being cut, that state is maintained. Then, repeat the above steps for a certain period of time 4
Repeat immediately.

With this kind of configuration, a fuel cut will be performed when the vehicle is decelerated by so-called engine braking, but this system prevents the intake pipe negative pressure from becoming closer to a vacuum than a constant value. Instead of making the fuel cut a necessary condition, the fuel cut is made on the condition that the intake pipe negative pressure is on the lighter load side than a curve that approximates the road load curve. Therefore, in all vehicle speed ranges, fuel can be cut close to the limit at which drivability deteriorates, and the fuel cut range can be significantly expanded compared to conventional systems. That is, roughly speaking, it is possible to make one fuel cut even in the area above the solid line A and below the imaginary line B (see IH), which could not be a fuel cut area in the past. becomes. Therefore, it is possible to effectively improve fuel economy without causing deterioration of drivability, and along with this, it is possible to reduce harmful components in exhaust gas and improve catalyst efficiency. This makes it possible to effectively suppress heating phenomena and the like.

In addition, in the embodiment 1- below, a case has been described in which the fuel cut is performed based on a single curve d regardless of the shift position of the transmission. For example, Toranosmin Yon is not limited to 3-speed, 4-speed
The road load curves for 1st and 5th speeds, or curves that approximate these, are stored in the storage device, and the curves that serve as the reference for -fuel cut are used depending on the shift I position during actual driving. It may be possible to separate them.

Furthermore, in the above section, a case has been described in which intake pipe negative pressure is detected as the engine load, but the present invention is not necessarily limited to this. For example, the throttle opening may be used as the engine load. You can also do this. In other words, in the relationship between throttle opening and vehicle speed, there is a road load curve as shown by the solid line P in Figure 5, and the fuel cut is performed based on this road load curve or a curve similar to this. You may also do this.

Further, the I4 and both speeds may be indirectly known by measuring the engine rotational speed.

(f) Effects Since the present invention has the above-described configuration, the fuel cut area can be expanded without causing deterioration of drivability, and the fuel economy can be improved without reducing fuel economy. Accordingly, it is possible to provide a fuel cut device for a vehicle engine that can effectively prevent catalyst heating.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is an explanatory diagram for explaining a road load curve. 2 to 4 show an embodiment of the present invention, FIG. 2 is a system explanatory diagram, and FIG. 3 is an explanation for explaining a method of setting a curve serving as a reference for control. is a flowchart diagram. FIG. 5 is an explanatory diagram corresponding to FIG. 3 showing another embodiment of the present invention. l Conflict... Carburetor 2911 Throttle valve 3... Slow system fuel passage 4... Main system fuel passage 6.7... Life fuel car 2 top valve 9... Arithmetic processing unit 10... Description ( , IJ device 13... φ vehicle speed sensor 14... Engine load detector agent Patent attorney Hiroshi Akazawa Figure 1 ■ Reason for dispute - Gao Liao Figure 3 Comparison degree (in m/h) 4th Figure 5 Rito Kurumayama

Claims (1)

[Claims] A fuel cut means for cutting off the fuel passage, and a road load curve showing the engine load limit point at which the speed change rate of the vehicle exceeds a predetermined value when the fuel is cut off, corresponding to each vehicle speed. If a storage device stores a curve approximating this curve, the curve in this storage device is compared with the actual engine load corresponding to the vehicle speed during actual driving, and the actual engine load at that vehicle speed is calculated as shown above. 1. A fuel cut device for a vehicle engine, comprising: an arithmetic processing unit that outputs a fuel cut signal (No. 4) to the fuel cut means when the load is on the light load side of a curve.