JPS61218744A - Fuel-cut system - Google Patents

Abstract

PURPOSE:To effectively improve economic efficiency by executing fuel-cut by switching a fuel-cut valve from opened position to cut-off position when the output torque of an engine reduces to a little decleration region. CONSTITUTION:A microcomputer system 7 judges if the little deceleration fuel- cut execution conditions where a throttle valve 2 returns to the vicinity of a closure position and the engine output torque becomes zero or less are met or not in traveling. When the condition is met, a fuel-cut signal (d) is inputted into fuel-cut valves 5 and 6, and fuel cut is executed by switching the both valves 5 and 6 from opened position to cut-off position. Thus, fuel economic efficiency can be improved effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a vine cut system mainly applied to carrots for automobiles.

[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 related to this type of fuel cut system, the previously filed patent application No. 58-17664
As shown in No. 0, a fuel cut pulp is provided in the fuel supply path communicating with the engine's intake system, and a predetermined deceleration operation range (this specification) in which the accelerator is completely released and the throttle valve is closed is provided. In this manual, this operating region is abbreviated as "large deceleration region").
The valve is moved from the open position to the closed position! ! (The "blocking position" as used in this specification includes not only a position where the fuel supply path is completely closed, but also a position where a small amount of fuel is allowed to flow).

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's output torque may drop to approximately zero. Therefore, it is theoretically possible to perform fuel cut in such an operating region (hereinafter referred to as "small deceleration fuel cut region") in this operating region (hereinafter referred to as "small deceleration fuel cut region"). In this way, the fuel economy can be further improved than that of the prior art.

However, if the car only has this, if the throttle valve is slowly opened by slowly stepping on the accelerator during fuel cut in the small deceleration fuel cut region (hereinafter referred to as a case of slow acceleration), this Until the opening of the throttle valve leaves the above-mentioned small deceleration fuel cut area, the fuel car/ )
Since this is not released, there is a problem in that the return of fuel is delayed and a stalemate occurs.

Furthermore, at the start of acceleration, the air-fuel mixture temporarily becomes lean, so unless rich fuel is supplied, drivability will deteriorate. Therefore, even when the above-mentioned slow acceleration is performed, it is desirable to not only cancel the fuel cut but also supply auxiliary fuel to improve drivability.

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 account the fact that the fuel is cut even in the small deceleration range mentioned above, and cannot solve the above-mentioned problem.

[Problems to be Solved by the Invention J Kokuhatsu 11 was made with a focus on these 8 situations, and it is possible to effectively improve fuel economy by cutting fuel even in a small deceleration range, and It is an object of the present invention to solve the problem that breathing occurs when slow acceleration is performed in the small deceleration region, and to improve cartwheeling performance during the slow acceleration.

[Means for Solving the Problems] In order to achieve the L1 objective, the present invention provides a fuel supply path that communicates with the intake system of the engine, as shown in FIG. A fuel cut valve (5), (6) for shutting off the fuel, a fuel injection means (4) for replenishing the intake system with auxiliary fuel corresponding to the injection command signal, and a throttle valve (2) for supplying the intake system with fuel cut off during driving. ) is returned to a region near the closed position, whereby the output torque of the engine becomes approximately zero or less, and a fuel cut command means (26) that outputs a fuel cut signal when the output torque of the engine decreases to an upper region; The throttle valve (2) after outputting the fuel car signal
a minimum opening degree storage means (32) for storing the lowest value of the opening degree as the minimum opening degree;
the fuel cut release command means (28), and the throttle valve (28) within the fuel cut area i.
) a second fuel cut release command means (29) that outputs a fuel cut release signal and also outputs an injection command signal to the fuel injection means (4) when the opening degree exceeds the minimum opening degree by a set value or more. and when a fuel cut signal is output from the fuel cut command means (26), the fuel cut valves (5) and (6)
A fuel cut start means (27) for switching from the open position to the cutoff position, and the fuel cut when a fuel cut release signal is output from the first or second fuel cut release command means (28) or (29). The present invention is characterized in that it is equipped with fuel cut release means (31) for switching the valves (5) and (6) from the shutoff position to the open position.

According to such a configuration, when the throttle valve (2) is returned to a region near the closed position while the vehicle is running, and 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 (26) outputs a fuel cut signal, and the fuel cut start means c27> outputs a fuel cut signal.
5).

(6) Switch from the open position to the cutoff position and execute the fuel cut. After outputting this fuel cut signal, the lowest opening degree of the throttle valve (2) is stored as the lowest opening degree in the lowest opening degree storage means (32), and
If the fuel car is substantially out of the small deceleration fuel car/ Based on this, the fuel cut release means (31) switches the seven fuel cut valves (5) and (6) from the shutoff position to the open position. Further, even if the opening degree of the throttle valve (2) is still within the small deceleration fuel cut region, if the opening degree of the throttle valve (2) exceeds the minimum opening degree by more than a set value, the second The fuel cut release command means (29) outputs a fuel cut release signal to cause the fuel cut release means (31) to switch the fuel cut valves (5) and (6) from the shutoff position to the open position, and also causes the fuel injection means ( 4) outputting an injection command signal to replenish the intake system with an amount of auxiliary fuel corresponding to the injection command signal; Therefore, even if slow acceleration is performed during small deceleration and fuel cut, there is no inconvenience such as breathing, and drivability during slow acceleration is improved.

[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 a fuel cut system according to the present invention, in which 1 is a carburetor of an automobile engine, 2 is a throttle valve of this carburetor l, 3 is a float chamber, and 4 is an injection command. This is a fuel injection means for replenishing the intake system with an amount of auxiliary fuel corresponding to the signal f. Moreover, 5.6 is a fuel cut valve provided in a main system passage and a slow system passage (not shown), which are fuel supply paths of the carburetor I, respectively. And 7 is a microcomputer system.

The fuel injection means 4 has an inlet 12 having a check valve 11 connected to the float chamber 3 via an inlet passage 13, and an outlet 14 connected to the carburetor l via an outlet passage 16 having a check valve 15. The air intake passage 1a was opened. The fuel replenishment pump 17 includes a TM-type refueling pump (SAP) 17 and a driver 18 that drives the refueling pump 17 a number of times corresponding to the injection command signal f output from the microcomputer system 7. The refueling pump 17 has a piston 2 in a cylinder zl forming a pump chamber 19.
2, and the piston 22 is moved forward and backward by the urging force of a spring 23 and the electromagnetic attraction force of a solenoid 24 to perform a pump function. Further, the driver 18 applies a pulse voltage to the solenoid 24 to move the piston 22 of the refueling pump 17 forward or backward, and applies one pulse of driving voltage to the solenoid 24 of the refueling pump 17. Each time the piston 22 is reciprocated, the refueling pump 17
A certain amount of fuel is discharged from the engine. Therefore, when the number of pulses to be applied is increased, the number of times the refueling pump 17 is driven increases and the amount of fuel discharged increases, and conversely, when the number of pulses is decreased, the number of times the refueling pump 17 is driven is decreased and the amount of fuel discharged is increased. It is starting to decrease.

4. The microcomputer system 7 includes fuel cut command means 26, fuel cut start means 27. First fuel cut release command means 2B, second
The fuel cut release command means 29° serves as the fuel cut release means 31 and the minimum opening storage means 32, and the central processing unit 1t33,
It includes a memory 34 and interfaces 35 and 36. Signals a, b, and C from the rotational speed sensor 37, throttle opening sensor 38, and vehicle speed sensor 39 are input to the interface 35, respectively, and the signals a, b, and C from the rotation speed sensor 37, the throttle opening sensor 38, and the vehicle speed sensor 39 are inputted to the interface 36, respectively, and the two-wheel cut valve 5. 6, a fuel cut signal d or a fuel cut release signal e is output, respectively, and the above-mentioned injection command signal f is output to the m fuel injection means 4. In addition, the rotation speed sensor 37
is for detecting the engine rotational speed ME, and uses, for example, an exhaust pulse. Further, the throttle opening sensor 38 includes, for example, a potentiometer that converts the opening of the throttle valve 2 into an analog electrical signal, and an A/D converter (not shown) that converts the output of this potentiometer into a digital electrical signal. Be prepared.

The microcomputer system 7 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.

Then, in step 52, the following procedure is performed.

The fuel cut opening degree TASCU, which is the throttle opening degree for executing the cut, is calculated. The fuel cut release rotation speed NRT is the lowest value of the engine rotation speed shown by the broken line in FIG. 4 (indicating the throttle opening VTA 8 and the engine rotation speed ME at which the fuel cut is canceled) The cut opening degree TASCUT is the fourth
As shown by the solid line in the figure (indicating the throttle opening VTA and engine speed ME at which fuel cut is started), the optimum throttle opening value for small deceleration fuel cut (engine output torque Next, in step 53, a match flag YFC9 (indicating whether or not the area is in the small deceleration fuel cut area) is selected in advance and mapped. If it is, the match flag YFCS is set to 1; if it is not in the small deceleration fuel cut region, it is set to zero). If the matching flag YFC5 is not 1, step 54
, the fuel cut release rotation speed NRT is changed to a value obtained by adding a hysteresis amount (200 rpm) to the rotation speed NRT calculated in step 51, and the throttle opening VτA and Set engine speed ME. If l, proceed to step 55 and set the fuel cut opening degree TASCUf.
The opening degree TASCU calculated in step 52 is changed to a value obtained by adding a hysteresis amount (3 degrees), and the throttle opening degree VT^ and engine speed ME at which the small deceleration fuel cut is canceled are set. In this way, chattering can be prevented by providing hysteresis between the scr-, torque opening degree vTA, and engine speed ME at which small deceleration fuel cut is started and those at which it is canceled. Next, in step 56, the actual engine rotation speed M detected by the rotation speed sensor 37
Determine whether E is greater than or equal to the fuel cut release rotation speed NRT, and if the fuel cut release rotation speed is greater than or equal to the fuel cut release rotation speed NRT, proceed to step 57, and if it is less than the fuel cut release rotation speed NRT, proceed to step 61, respectively. 5
In step 7, it is determined whether the vehicle speed 52 detected by the vehicle speed sensor 39 is 40 Km/h or more, and if it is 40 Km/h or more, the process proceeds to step 58, and if it is less than 40/h, the process proceeds to step 61. 58 determines whether the actual throttle opening VTA detected by the throttle opening sensor 38 is smaller than the fuel cut opening ASCUT, and if it is smaller, the process proceeds to step 59; if not, the process proceeds to step 61. In this way, in steps 56 to 58, the small deceleration fuel cut execution condition is met, that is, the engine rotation speed MK is set to the fuel cut release rotation speed N.
It is determined whether the following conditions are all satisfied: RT or higher, vehicle speed SPD is 40 Km/b or higher, and throttle opening VT^ is smaller than fuel cut opening TASCUt. If all of these conditions are satisfied, the small deceleration fuel cut execution condition is satisfied. At step 59, it is determined that the throttle valve 2 is returned to a region close to the closed position during driving and has entered a predetermined small deceleration 7-wheel cut region in which the output torque of the carrot becomes approximately zero or less. Go to and set match flag YFCJ to 11
Set. Further, 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. Match flag YF(:S is set to zero, and match flag YFC3I(
Once the acceleration judgment is performed, this match flag YFC3
Set I to l, otherwise set to zero)
is set to zero, and then in step 63 the minimum opening VT is set to zero.
After changing the value of ALL to the value of the actual throttle opening VTA, the process advances to step 69 and the fuel cart is released.

Further, when the process proceeds from steps 56 to 58 through step 59 to step 60, it is determined whether the coincidence flag YFC9I is 1 or not. If l, step 69
Go to and release 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 equal to or greater than the minimum opening degree VTALL. If the opening degree is less than the minimum opening VTALL, the process proceeds to step 65 and the value of the minimum opening VTALL is updated to the value of the actual throttle opening VTA, and if it is the minimum opening VTALL or more, the update is performed. Therefore, the low opening degree VTALL is determined from the time when the vehicle deceleration fuel cut is started, that is, after the fuel cut signal d is output until the fuel cut is released. Throttle opening VT
This is the lowest value of A. 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). And the minimum opening VT
If it is smaller than the sum of ALL and the set value (1 degree), no acceleration determination is made, and since acceleration is not being performed, it is determined that there is no need to release the fuel cut, and the process proceeds to step 70 to execute the fuel cut. do. On the other hand, the minimum opening VTA
If it is greater than or equal to the sum of LL and the set value (1 degree), an acceleration determination is made, and since acceleration has started, it is determined that it is necessary to cancel the fuel cut, and a match flag YFC5 is set in step 67.
Add 1 to I by 7-2. Then, proceed to step 68,
In step 68, the refueling pump (SAP) 17 is operated by the number of times FTCLLI is multiplied by the temperature coefficient KWL corresponding to the engine cooling water temperature to supply auxiliary fuel to the vaporizing gll, and in step 69, the fuel is cut. Release.

Note that the microcomputer system 7 also separately stores a program to cut the fuel in the above-mentioned large deceleration range.

Since this is a normal thing, the 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 one-rotation speed sensor 37, throttle opening sensor 38, and vehicle speed sensor 39 to the interface 35 of the microcomputer 7. The generated information is input to the central processing unit 33. Also,
Memory device! From the table 134, the fuel cut release rotation speed NRT and the fuel cut opening degree TASCυ↑ corresponding to the engine rotation speed MH are determined by the central processing unit 33.
(steps 51 and 52), and a small deceleration fuel cut area is set in the central processing unit 33 (steps 53 to 55).

Next, small deceleration fuel cut execution conditions (engine speed ME is north of fuel cut release speed NRT, vehicle speed is 40 km/hr or more, and throttle opening VTA is specified by engine speed) If the fuel cut opening degree (↑ smaller than ASCUT) is established and acceleration determination is not performed, the fuel cut signal d is output to the fuel cut valve 5.6 via the interface 36, and the fuel cut valve 5. 6 from the open position to the cut-off position and execute the fuel cut (steps 56 to 58 → 59 → 60 →
64 → (65) → 66 → 70), and if acceleration is determined even if the small deceleration fuel cut execution conditions are met, an injection command signal f is output to the driver 18 via the interface 36, and the driver 18 to the number of times corresponding to this injection command signal f, that is, the number of driving times FTCLL
IX temperature coefficient KIIL pulse voltage is applied to the fuel replenishment pump 17 to discharge auxiliary fuel to the carburetor I, and a fuel cut release signal e is output to the fuel cut valve 5.6 to close the fuel cut valve. 5. Switch 6 from the shutoff position to the open position to release the fuel cut (steps 56 to 58 → 59 → 60 →
64 → 66 groan 67 → 68 → 69), and if acceleration judgment has already been performed, continue canceling the fuel cut (steps 56 to 58 → 59 → 60 → 69), and execute small deceleration fuel cut If the condition is not met, 1. Release the fuel cart or continue releasing the fuel cart (steps 56 to 58 → 61 → 62 → 63 →
69).

In this way, the fuel cut is executed or canceled. According to this embodiment, even when the small deceleration fuel cut region is not substantially exceeded, the throttle opening VTA is equal to the minimum opening VTALL. Setting 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 II&acceleration is performed, there is no problem such as engine sluggishness that occurs in those that do not have such a system.Especially, in this embodiment,
In order to prevent chattering, the throttle opening for canceling the small deceleration fuel cut is set higher than the opening for starting the small deceleration fuel cut, which further delays exiting the small deceleration funi nil cut region. Therefore, the present invention is more effective. Furthermore, since the auxiliary fuel is supplied to the carburetor 1 when the fuel cut is canceled due to the above-mentioned slow acceleration, the air-fuel mixture is temporarily thinned at the start of acceleration, resulting in poor drivability. There is no inconvenience such as deterioration, and drivability is improved. Furthermore, once the small deceleration fuel cut is canceled due to slow acceleration, the fuel cut is not restarted even if the small deceleration fuel cut execution condition is met, so there is no problem such as chattering.

In the above embodiment, the fuel cut command means, the fuel cut start means, the first fuel cut release command means, the second fuel cut release command means, the fuel cut release means, and the minimum opening storage means are configured by a microcomputer system. Although the above-mentioned case has been described, each of the above-mentioned elements 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 J As explained below, the present invention can effectively improve fuel economy because fuel is cut even in a small deceleration range, and moreover, in the small deceleration range, It is possible to solve the problem of breathing during slow acceleration with a simple configuration, and to provide a fuel cut system that can improve drivability during slow acceleration.

4. Brief Explanation of Surfaces FIG. 1 is an explanatory diagram of the structure 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.

■#Red red circle carburetor fist...Throttle valve 4φ...Fuel injection means 5, 6...Fuel cut valve 7...Microcomputer system 26...Fuel cut command means 27 Fist...Fuel cut starting means 28 ...-First fuel cut release command means 29, second fuel cut release command means 3111, fuel cut release means 32, life number low opening storage means

Claims (1)

[Claims] A fuel cut valve for cutting off a fuel supply path communicating with the intake system of the engine; a fuel injection means for supplying the intake system with an amount of auxiliary fuel corresponding to an injection command signal; a fuel cut command means for outputting a fuel cut signal when the engine output torque decreases to a predetermined fuel cut region where the engine output torque becomes approximately zero or less by returning to a region near the closing position; a minimum opening storage means for storing a minimum value of the opening as the minimum opening; a first fuel cut release command means for outputting a fuel cut release signal when the fuel cut is substantially out of the fuel cut region; a second fuel cut release command means for outputting a fuel cut release signal and an injection command signal to the fuel injection means when the opening degree of the throttle valve exceeds the minimum opening degree by a set value or more; 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 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 release signal is output from the first or second fuel cut release command means. A fuel cut system for an engine, comprising a fuel cut release means for switching the fuel cut valve from a closed position to an open position.