JPS61212642A - Fuel cut system - Google Patents

Abstract

PURPOSE:To enable discontinuous combustion in gentle acceleration to be prevented, by outputting a fuel cur release signal if the minimum opening of a throttle valve exceeds a preset value or more even in a fuel cut region of small deceleration, in the case of an automobile engine. CONSTITUTION:A throttle valve 2 is returned to a region in the vicinity of a closed position in running operation of a car, and if output torque of an engine decreases to a fuel cut region of small deceleration with the torque being almost below zero, a command means 7, outputting a fuel cut signal, closes a fuel cut valve 4 through a means 8. And then the minimum opening of the throttle valve 2 is stored in a memory means 12. And when the torque is out of the small deceleration fuel cut region or if the minimum opening of the throttle valve 2 even in said region exceeds a preset value or more, a command means 9, outputting a fuel cut release signal, switches the valve 4 to an open position through a release means 11. In this way, the engine promotes the improvement of its fuel consumption further enable discontinuous combustion to be prevented when gentle acceleration is performed in a small deceleration range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel cut system mainly applied to automobile engines.

[Prior Art] Many modern automobile engines are equipped with a fuel cut system that cuts fuel during deceleration in order to improve fuel economy.

As a prior art regarding this type of fuel car I) system, the previously filed patent application No. 58-1766
As shown in No. 40, a fuel cut valve is provided in the fuel supply path communicating with the engine intake system,
The fuel car/
from the open position to the shutoff position (referred to in this specification as "
"Cutoff position" includes not only a position where the fuel supply route is completely closed, but also a position where a small amount of fuel is allowed to flow)
There is one that allows you to switch to .

By the way, if you look at the driving conditions more closely, you will find that there are driving regions where the accelerator is not fully released, in other words, driving regions where the throttle valve is returned to near the closed position and the vehicle is running inertia or descending. In,
The engine output torque may become approximately zero or less. Therefore, it is theoretically possible to perform a fuel cut in such an operating region (hereinafter referred to as the "small deceleration fuel cut region") in this operating region (hereinafter referred to as the "small deceleration fuel cut region"). In this way, the fuel economy can be further improved than that of the prior art. However, this is only the case when the throttle valve is opened slowly by slowly stepping on the accelerator during the fuel cut in the small deceleration fuel cut region (hereinafter referred to as a case of slow acceleration).

Since the fuel cut is not canceled until the opening degree of the throttle valve leaves the small deceleration fuel cut region, there is a problem in that the return of fuel is delayed accordingly and breathing occurs.

In addition, as a prior art related to a vehicle having a fuel cut system that cuts fuel during deceleration, which smoothly transitions from deceleration to acceleration operation, as shown in JP-A-56-72246, There are some models that can supply auxiliary fuel to the carburetor when transitioning from deceleration to acceleration. However, this method does not take into consideration the fact that the fuel is cut even in the small deceleration range mentioned above, and cannot solve the above-mentioned problems.Furthermore, it requires a special mechanism to supply auxiliary fuel. However, the configuration becomes more complicated.

[Problems to be solved by the invention] The present invention has been made with attention to these circumstances, and
To effectively improve fuel economy by performing a fuel cut in a small deceleration range, and to solve the problem of breathlessness occurring when slow acceleration is performed in the small deceleration range, with a simple configuration.

Means for Solving the L Problem] In order to achieve the above object, the present invention uses a fuel cut system to cut off the fuel supply path (5) communicating with the intake system of the engine, as shown in FIG. a fuel cut valve (4) for reducing engine speed, and a predetermined 7 fuel cut region where the engine output torque becomes approximately zero or less by returning the throttle valve (2) to a region near the closed position during driving, that is, a small deceleration fuel cut. a fuel cut command means (7) that outputs a fuel cut signal when the fuel has decreased to a certain level; and the above-mentioned slot after outputting the fuel cut signal.

minimum opening storage means (12) for storing the lowest opening degree of the throttle valve (2) as the minimum opening degree; valve(
A fuel cut signal is output from the fuel cut release command means (9), which outputs the fuel cut release means when the opening degree of 2) exceeds the minimum opening degree by a set value or more, and the fuel cut command means (7). a fuel cut start means (8) for switching the fuel cut valve (4) from the open position to the cutoff position when the fuel cut valve (4) is opened; and a fuel cut start means (8) for switching the fuel cut valve (4) from the open position to the cutoff position; The present invention is characterized in that it is equipped with a fuel cut release means (11) for switching the valve (4) from the shutoff position to the open position.

[Operation] According to such a configuration, when the throttle valve (2) is returned to a region near the closed position while the vehicle is running, the output torque of the engine decreases to a small deceleration fuel cut region where it becomes approximately zero or less. , the fuel cut command means (7) outputs a fuel cut signal, and the fuel cut start means (8) outputs the 7 fuel cut valve (4).
) is switched from the open position to the cutoff position and the fuel cut is turned off. After outputting this fuel cut signal, the lowest opening degree storage means (12) stores the lowest opening degree of the throttle valve (2) as the lowest opening degree, and while this fuel cut is being executed, the small deceleration fuel cut is performed. If the opening degree of the throttle valve (2) exceeds the minimum opening degree by more than a set value even if the opening degree of the throttle valve (2) is still within the small deceleration fuel cut area. In this case, the fuel cut release command means (9) outputs a fuel cut release signal, and based on this fuel cut release signal, the fuel cut release means (11) activates the fuel cut valve (
4) Switch from the shutoff position to the open position. Therefore, even if slow acceleration is performed during execution of small deceleration and fuel cut, there is no problem such as breathing.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 2 to 4.

Fig. 2 is a system explanatory diagram of the fuel cut system according to the present invention, in which 1 is the carburetor of an automobile engine, and 2 is the carburetor! 11 is a throttle valve, and 3 is a float chamber. 4 is a fuel cut valve,
They are provided in a main system passage 5a and a slow system passage 5b, which are fuel supply paths 5 of the carburetor I, respectively. and,
6 is a fuel cut command means 7. Fuel cut initiation means8. This is a microcomputer system that functions as a fuel cut release command means 9, a fuel cut release means 11, and a minimum opening storage means 12.

The microcomputer system 6 includes a central processing unit 13, a memory 14, and interfaces 15, 16. Signals a, b, and C from the throttle opening sensor 17, rotation speed sensor 188, and vehicle speed sensor 19 are input to the interface 15, respectively, and the signals are directed from the interface 16 to the tube cut valve 4. A fuel cut signal d or a fuel cut release signal e is output. The throttle opening sensor 17 includes, for example, a potentiometer that converts the opening of the throttle valve 2 into an analog electrical signal, and an A/D converter that converts the output of this potentiometer into a digital electrical signal.
and a D converter (not shown). Further, the rotation speed sensor 18 is for detecting the rotation speed ME of the engine, and uses, for example, an ignition pulse.

The microcomputer system 6 has a built-in program as schematically shown in FIG. First, in step 51.

A fuel cut release rotation speed NRT, which is the engine rotation speed at which the fuel cut is canceled, is calculated.

Next, in step 52, the fuel cut opening degree TA, which is the throttle opening degree at which the fuel cut is executed, is determined.
Calculate SCUT. The fuel cut release rotation speed NR is shown in FIG. 4 by a broken line (throttle opening VTA and engine rotation speed
In addition, the fuel cut opening degree 11,501 is the lowest value of the engine speed indicated by the solid line (the throttle opening VT at which the fuel cut starts) in Fig. 4.
A and engine speed ME), select in advance the optimal throttle opening value for small deceleration fuel cut defined by engine speed ME (throttle opening at which the engine output torque becomes approximately zero). Next, in step 53, a match flag vFC5 indicating whether or not the area is in the small deceleration fuel cut area (if it is in the small deceleration fuel cut area, this match flag YFC3 is set to 1). , set to zero if it is not in the small deceleration fuel cut area)
is set to 1. If the coincidence flag YFC5 is not 1, the process proceeds to step 54, where the fuel cut release rotation speed NR↑ is added to the rotation speed calculated in step 51) IRT by hysteresis (
200 rpm), and set the throttle opening VTA and engine speed ME at which the small deceleration fuel cut is started. Also, if l, step 55
, the fuel cut opening degree TASCUT is changed to a value obtained by adding the hysteresis amount (3 degrees) to the opening degree TASCUT calculated in step 52, and the throttle opening degree VTA and engine at which the small deceleration fuel cut is canceled are changed. Set the rotation speed NE. In this way, chattering can be prevented by providing hysteresis between the throttle opening VTA and engine rotation aNE at which the small deceleration fuel cut is started and those at which the small deceleration fuel cut is released.Next, in step 56 Then, it is determined whether the actual engine rotation speed ME detected by the rotation speed sensor 18 is equal to or higher than the fuel cut release rotation speed NRT, and if the actual engine rotation speed ME detected by the rotation speed sensor 18 is equal to or higher than the fuel cut release rotation speed NRT, the process proceeds to step 57. If it is less than NR, the process proceeds to step 61. In step 57, the vehicle speed 82 detected by the vehicle speed sensor 19 is 40K.
Determine whether or not the speed is above 40 Km/h, and if it is above 40 Km/h, proceed to Step 5B. If it is less than 40 Km/h, proceed to Step 61. Step 58 is the throttle speed sensor 1.
The actual throttle opening VTA detected by 7 is the fuel cut opening TA! It is determined whether or not it is smaller than 3CUT, and if it is smaller, the process goes to step 59, and if it is not, the process goes to step 61. In this way, in steps 56 to 58, the small deceleration fuel cut execution conditions are set, that is, Engine speed ME is fuel cut release speed 1
It is determined whether the following conditions are all satisfied: 1 RT or more, vehicle speed SPD is 40 kmlb or more, and throttle opening HA is smaller than fuel cut opening TABCUT. If all of these conditions are satisfied, the small deceleration fuel cut execution condition is satisfied. In other words, it is determined that the engine has entered a predetermined small deceleration fuel cut region in which the output torque of the engine becomes approximately zero or less due to the throttle valve 2 being returned to a region near the closed position M during driving, and step 59 Proceed to , and set match flag YF (:1 to S).
If even one of the execution conditions is not satisfied, it is determined that the small deceleration fuel cut execution condition is not satisfied and the process proceeds to step 61.
If the process proceeds to step 61, the match flag YFC9 is cleared in step 61, and the match flag YFC81 indicates whether or not acceleration was determined in Step 2 Pro 2. (set to 1, otherwise set to zero), and then change the minimum opening VTALL value to the actual throttle opening VTA value in step 63, and then proceed to step 68 to cut the fuel. unlock.

In addition, if the process proceeds from steps 56 to 58 to step 59 to step 2 pro 0, the match flag YFC5I
is 1 or not. And if it is 1 then step 6
Proceed to step 8 to cancel the fuel cut. On the other hand, if it is not 1, the process proceeds to step 64. In step 64, it is determined whether the actual throttle opening degree VTA is greater than or equal to the minimum opening degree VTALL. Then, if the minimum opening VTALL is not vortex, proceed to Stay, Pro 5 and change the minimum opening VTALL.
After updating the value of the actual throttle opening V↑Todoroki,
If the minimum opening degree VTALL is greater than or equal to the minimum opening degree VTALL, the process proceeds to step 66 without updating. Therefore, the minimum opening degree VTALL is changed after the small deceleration fuel cut is started, that is, after the fuel cut signal d is output. This is the lowest value of the throttle opening VTA from 1 to 2 until the fuel cut is canceled. In step 66, it is determined whether the actual throttle opening degree VTA is smaller than the sum of the minimum opening degree VTALL and the set value (1 degree). If the opening degree is smaller than the sum of the minimum opening degree VTALL and the set value (1 degree), no acceleration judgment is made, and IIa arrest is not performed, so 7
Determining that there is no need to release the user cut, proceed to step 6.
Proceed to step 9 and perform a fuel cut. On the other hand, if it is greater than or equal to the sum of the minimum interval j [VTALL and the set value (1 degree), acceleration is determined, and since acceleration has started, it is determined that it is necessary to cancel the fuel cut, and the match flag YFC3I is set in step 67. 1 is set and the fuel cut is canceled in step 68.

Note that the microcomputer system 6 also separately stores a program for performing a fuel cut in the above-mentioned large deceleration region, but since this is a normal program, its explanation will be omitted.

Next, the operation of this device will be explained.

While the vehicle is running, signals a, b, and c are constantly input from the throttle opening sensor 17, rotation speed sensor 18, and vehicle speed sensor 19 to the interface 15 of the microcomputer 6. The generated information is input to the central processing unit 113. Further, from the table in the storage device 14, the fuel cut release rotation speed NRT and the seven-wheel cut opening degree TASCUT corresponding to the engine rotation speed NE are stored in the central processing unit 14.
(steps 51 and 52), and a vehicle deceleration fuel cut area is set in the central processing unit 13 (steps 53 to 55).

Next, the small deceleration fuel cut execution conditions (engine rotational speed ME is higher than the fuel cut release rotational speed NRT, vehicle speed is 40km/hr or higher, and throttle opening VTA is the fuel specified by the engine rotational speed) If the cut opening degree TAS (: [smaller than IT) is established and acceleration determination is not performed, the fuel cut signal d is output to the fuel cut valve 4 via the interface 16, and the fuel cut valve 4 Switch from the open position to the cutoff position and execute the fuel cut (steps 56 to 58 → 59 → 60 → 64
+ (65) → 66 → 69), and if acceleration is determined even if the small deceleration fuel cut execution conditions are met, a fuel cut release signal e is output to the fuel cut valve 4 via the interface 16. Then, the fuel cut valve 4 is switched from the cutoff position to the open position to release the fuel cut. Steps 56 to 58-
59 → 60 groan 64 → 66 → 67 → 68), if acceleration judgment has already been performed, continue canceling the fuel cut (steps 56 to 58 → 59 → 60 → 68), and execute small deceleration fuel cut If the conditions are not met, cancel the fuel cut or continue canceling (steps 56 to 58 → 61 → 62 → 63 → 68)
.

In this way, the fuel cut is executed or canceled, but according to this embodiment, even when the small deceleration fuel cut is not substantially out of the 1i range,
The throttle opening VTA is the minimum opening VTALL and the set value (
1 degree), the fuel cut is canceled and the fuel is restored.

Therefore, since the fuel cut is canceled even when the above-mentioned gentle acceleration is performed, problems such as engine sluggishness that occur in engines that do not have such a system do not occur, and in particular, in this embodiment, there is no chattering. To prevent this, the throttle opening at which the small deceleration fuel cut is canceled is set higher than the opening at which the small deceleration fuel cut is started, so that exiting the small deceleration funi nil cut region is further delayed. Therefore, (1) the present invention is more effective.Furthermore, when the small deceleration fuel cut is canceled due to slow acceleration, the fuel cut is not restarted even if the above-mentioned ``small deceleration fuel cut execution condition'' is met, so chattering occurs. There is no inconvenience to do so.

Moreover, since a complicated mechanism such as a mechanism for supplying auxiliary fuel is not required, this problem of breathing can be solved with a simple configuration.

In the above embodiment, the fuel cut command means, the fuel cut start means, the fuel cut release command means, the fuel cut release means, and the minimum opening storage means are configured by a microcomputer system. Each may be configured by a dedicated circuit.

Further, although it may be applied to a throttle valve that does not have hysteresis in the fuel cut opening degree, it is more effective if it is applied to a throttle valve that does have hysteresis.

[Effects of the Invention] As explained above, the present invention performs a 7 fuel cut in the small deceleration region, so that fuel economy can be effectively improved. It is possible to provide a fuel cut system that can solve the problem of breathing when accelerating with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a configuration explanatory diagram for clearly explaining the present invention. 2 to 4 show an embodiment of the present invention, FIG. 2 is a system explanatory diagram, FIG. 3 is a flowchart showing a control procedure, and FIG. 4 is an explanation for explaining control setting conditions. It is a diagram. L・E・Carburizer 2...Throttle valve 4...Fuel cut pulp 5...Fuel supply path 6...Microcomputer system 7...Fuel cut command means 8...Fuel cut start means 9 ...Fuel cut release command means 11...Fuel cut release means 12-...Minimum opening degree storage means

Claims (1)

[Claims] A fuel cut valve is used to cut off the fuel supply path that communicates with the engine's intake system, and a predetermined valve that reduces engine output torque to approximately zero or less when the throttle valve is returned to a region near the closed position during driving. a fuel cut command unit that outputs a fuel cut signal when the fuel cut signal has decreased to a fuel cut region; and a minimum opening storage unit that stores the lowest value of the opening degree of the throttle valve after outputting the fuel cut signal as the minimum opening degree;
a fuel cut release command means for outputting a fuel cut release signal when the throttle valve substantially deviates from the fuel cut region or when the opening degree of the throttle valve exceeds the minimum opening degree by a set value or more within the fuel cut region; a fuel cut start means for switching the fuel cut valve from an open position to a cutoff position when a fuel cut signal is output from the fuel cut command means; and a fuel cut start means for switching the fuel cut valve from an open position to a cutoff position when a fuel cut signal is output from the fuel cut release command means; 1. A fuel cut system for an engine, comprising: a fuel cut release means for switching the fuel cut from a cutoff position to an open position.