JPS635126A - Fuel cut control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent cutting of the feed of fuel during running in a very low load region, by a method wherein a throttle full closing switch and a throttle opening sensor are provided, and when a throttle opening is below a given value, it is decided that a throttle valve is brought into a full closed state, and the feed of fuel is cut. CONSTITUTION:A throttle position sensor 4 is situated to a throttle valve 3 of an intake air pipe 5. A position sensor 4 is provided with a moving contact 18 for detecting a throttle opening, attached on a plate rotated in linkage with the throttle valve 3, and a moving contact 19 for detecting full closing of a throttle. A control circuit 16 inputs a signal from a position sensor 4, a throttle full closing signal is detected, and when a throttle opening detecting signal is below a given value, the feed of fuel from an injection valve 8 is cut. This constitution enables high-precise detection of the full closed state of the throttle valve, and prevention of cutting of the feed of fuel during very low load running.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel cut control device for an internal combustion engine, and more particularly to a fuel cut control device for an internal combustion engine that stops the supply of fuel during deceleration.

[Conventional technology]

Conventionally, internal combustion engines have been equipped with a fuel cut control device that injects fuel based on the basic fuel injection time determined based on the engine speed and engine load (intake air amount or intake pipe pressure), and stops fuel injection during deceleration. The institution is known. This fuel cut control device determines the state of deceleration based on the on/off state of the throttle fully closed switch, which is turned on when the throttle valve is close to fully closed, and determines whether or not to stop fuel injection based on the engine rotation speed. When the throttle fully closed switch is on and the engine speed is above the fuel cut speed, fuel injection is stopped and the fuel cut is executed, and when the throttle fully closed switch is on, the engine speed is When the rotational speed becomes lower than the fuel injection return rotational speed, which is lower than the fuel cut rotational speed, fuel injection is resumed. Incidentally, as a technique related to fuel cut, there is a technique described in Japanese Patent Application Laid-Open No. 56-92332.

[Problem that the invention seeks to solve]

However, the throttle opening is -1.5± for boat fishing.
There is a tolerance of 0.5° or less, and therefore, even when the throttle valve is not completely closed, the throttle valve fully closed switch may output a throttle valve fully closed signal (on signal). Therefore, when operating in an extremely low load range, the throttle fully closed switch is turned on, and if the engine speed at this time exceeds the fuel cut speed, a fuel cut is executed and the driver intends to decelerate. Even when the vehicle is not in use, the vehicle will be decelerated and the feeling will deteriorate. In particular, in large internal combustion engines, the diameter of the throttle valve becomes large due to the large bore diameter.
Since the direction tolerance is between a small internal combustion engine and a road, the throttle fully closed switch is turned on even when the amount of intake air is large, and the above-mentioned tendency becomes noticeable.

The present invention has been made to solve the above problems, and is a fuel cut control for an internal combustion engine that prevents a fuel cut from being executed during operation in an extremely low load range by increasing the detection accuracy when the throttle valve is fully closed. The purpose is to provide equipment.

[Means for solving problems]

To achieve the above object, the present invention provides a rotational speed sensor that detects engine rotational speed, a throttle fully closed switch that outputs a throttle fully closed signal when the throttle valve is near fully closed, and a throttle valve opening degree. a throttle opening sensor that detects the throttle opening and outputs a throttle opening signal corresponding to the opening; a storage means that stores a determination level corresponding to a throttle valve fully closed state; and a storage means that outputs the throttle fully closed signal. In some cases, the output of the throttle opening sensor is compared with the determination level to determine whether the throttle valve is in a fully closed state, and whether or not to stop the fuel supply based on the engine rotation speed. The fuel supply system is configured to include a determining means for determining, and a fuel supply stop means for stopping the supply of fuel based on the determination result of the determining means.

[Effect]

According to the present invention, the engine rotation speed is detected by the rotation speed sensor, the throttle opening is detected by the throttle opening sensor, a throttle opening signal corresponding to the throttle opening is output, and the throttle valve is fully closed. When the throttle is located nearby, the throttle fully closed switch outputs a throttle fully closed signal. The storage means stores a determination level corresponding to the throttle valve fully closed state, and the determination means compares the throttle opening sensor output with the determination level to determine whether the throttle valve is in the fully closed state. do.

Whether or not the throttle valve is fully closed can be determined by determining whether the throttle opening sensor output has fallen below the determination level, and if this determination is affirmative, the throttle valve is fully closed. It is determined that it is located in the closed state. Further, the determination means determines whether or not to stop the fuel supply based on the engine rotation speed when it is determined that the throttle valve is in the fully closed state, and determines whether the engine rotation speed is equal to or higher than the fuel cut rotation speed. When the determination means determines that the fuel cut condition is met, it is determined that the fuel cut condition is satisfied.The fuel supply stop means stops the fuel supply when the determination means determines that the fuel cut condition is satisfied.

As described above, according to the present invention, the determination level corresponding to the throttle valve fully closed state is compared with the throttle opening sensor output to determine whether or not the throttle valve is in the fully closed state. It is possible to accurately detect the fully closed state of the throttle valve even if there is a tolerance in the opening degree, thereby achieving the intended purpose of preventing a fuel cut during operation in an extremely low load range. can do.

Accurately detecting the throttle valve fully closed state can also be achieved by simply comparing the throttle opening sensor output with the above judgment level, but with this configuration, when the throttle opening sensor is disconnected, There is also a risk that the throttle valve will be determined to be fully closed and a fuel cut will be executed during normal operation.

〔Effect of the invention〕

According to the present invention, when the throttle fully closed signal is output, that is, when the throttle valve is located near fully closed, it is determined whether the throttle valve is fully closed or not, and the fuel cut is executed. Therefore, even if a wire breakage or the like occurs in the throttle opening sensor, a unique effect can be obtained in that fuel cut can be executed only during deceleration.

(!IM's explanation) The present invention can be carried out in the following manner.

In a first aspect, a learned value that is updated to approach the throttle opening sensor output when the throttle fully closed signal is being output is stored as the determination level.

According to B48, the determination level is learned to be close to the throttle opening sensor output, so even if there is a tolerance in the throttle opening, the determination level is learned and converged to the value of the throttle valve fully closed state. The fully closed state of the throttle valve can be detected more accurately.

In the second aspect, in the first aspect, when the learned value is larger than the throttle opening sensor output, the learned value is updated more than when the learned value is smaller than the throttle opening sensor output. This is designed to speed up the process.

According to this aspect, when the learned value is larger than the throttle opening sensor output, that is, when the learning value is larger than the value corresponding to the actual throttle fully closed state, the learning value is updated so as to quickly approach the throttle opening sensor output. Therefore, if the learned value becomes abnormal due to tolerance, it can be brought closer to the normal value more quickly.

The third aspect is that when the learned value is smaller than the throttle opening sensor output, the difference obtained by subtracting the learning value from the throttle opening sensor output is compared with a predetermined value, and when the difference is larger than the predetermined value, the above The learning value is updated at a slower speed than when the difference is smaller than a predetermined value.

According to this aspect, when the difference is larger than the predetermined value, that is, when the throttle fully closed signal is output with a throttle opening larger than the throttle fully closed state due to the tolerance,
Since the learned value is updated slowly, the learned value is prevented from becoming abnormally large.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows an example of an internal combustion engine equipped with the fuel cut control device of this embodiment. This engine is controlled by an electronic control circuit such as a microcomputer, and is provided with an air flow meter 2 downstream of an air cleaner 1 to detect the amount of intake air.

The air flow meter 2 includes a compensation plate rotatably installed in the damping chamber, a measuring plate connected to the compensation plate, and a potentiometer that detects the opening degree of the measuring plate. Therefore, the intake air amount is determined from the intake air amount signal output from the potentiometer as a voltage value.

A throttle valve 3 is arranged downstream of the air flow meter 2, a throttle position sensor 4 is attached to the throttle valve 3, and a surge tank 17 is arranged downstream of the throttle valve 3. The surge tank 17 is connected to the engine via the intake manifold 5 and the intake port. It is connected to room A. Then, for each cylinder so as to protrude into the intake manifold 5,
Alternatively, a fuel injection valve (fuel injector) 8 is attached to each cylinder group. This fuel injection valve 8 is
It is configured to communicate with a fuel tank 6 via a fuel pump 7, and to supply fuel at a predetermined pressure to a fuel injection valve 8. Therefore, by opening the fuel injection valve 8 for a predetermined period of time, an amount of fuel corresponding to this period of time is injected.

The combustion chamber of the engine is communicated with a catalyst device (not shown) filled with a three-way catalyst via an exhaust boat and an exhaust manifold. An 02 sensor is attached to this exhaust manifold that outputs a signal determined based on the stoichiometric air-fuel ratio. Further, a cooling water temperature sensor 15 is attached to the engine block so as to penetrate the engine block and protrude into the water jacket.

This cooling water temperature sensor 15 detects the engine cooling water temperature and outputs a water temperature signal.

A spark plug 14 is attached to each cylinder so as to penetrate the cylinder head of the engine and protrude into the combustion chamber. This spark plug 14 is connected via a distributor 11, an ignition coil 10, and an igniter 9 to a control circuit 16 composed of a microcomputer or the like.

Inside the distributor 11, a cylinder discrimination sensor 13 and a rotation angle sensor 12 are installed, each of which includes a signal rotor fixed to a distributor shaft and a pickup fixed to a distributor housing. In the case of a 6-cylinder engine, the cylinder discrimination sensor 13 outputs a cylinder discrimination signal every 720° CA,
The rotation angle sensor 12 outputs an engine rotation speed signal every 30'' CA.

As shown in FIG. 3, the throttle position sensor 4 includes a movable contact 18 for detecting throttle opening and a movable contact 19 for detecting throttle fully closed, which are attached to a plate that rotates in conjunction with the throttle valve 3. ing. The movable contact 18 for throttle opening detection is arranged so as to slide on the arc-shaped resistor 20A and the resistor 21A printed in parallel on the base, and the movable contact 19 for throttle fully closed detection is disposed on the base. It is arranged so as to slide on the printed conductors 22A and 23A. Resistor 2
One end of 0A is electrically connected to the terminal Vc connected to the voltage a (sv), and the other end of the resistor 20A is connected to the grounded terminal E.
, is electrically connected to. Further, one end of the resistor 21A is connected to the terminal Vt, and one end of the conductor 23A is connected to the terminal I.
Connected to DL. The conductor 22A is connected to the terminal E.
.

electrically connected to.

Throttle position sensor 4 configured as above
FIG. 4 shows an equivalent circuit of the throttle opening detection movable contact 18 and the resistor 20A.

21A acts as a throttle opening sensor SN, and is connected to the movable contact 19 for detecting fully closed throttle and the conductor 22A.
, 23A act as a throttle fully closed switch SW. In addition, the terminal VT output and the terminal IDIL output are shown in Fig. 5. Therefore, the terminal IDL outputs a signal that turns on when the throttle valve is near the fully closed position, and the terminal V↑ outputs a signal that turns on when the throttle valve is close to fully closed. A throttle opening signal proportional to the degree is output.

Further, as shown in FIG. 6, the control device 16 includes a central processing unit (CPU) 20, a read-only memory (R
OM) Consists of a random access memory (RAM>22) with backup memory (RAM>22), an input port 23, an output port 24, and buses 25 such as a data bus and a control bus that connect these.CPU
20 is connected to an air flow meter 2 and a terminal V of a throttle position sensor 4 via an analog-to-digital (A/D) converter 26 and a multiplexer 27, as well as a cooling water temperature sensor 15 (not shown). ing.

The CPU 20 controls the multiplexer 27 to sequentially input the air flow meter 2 output, the throttle position sensor 4 terminal ■ 1 output (throttle opening sensor output), etc., and starts the A/D converter 26 to convert the input signal into a digital signal. Convert it to a signal and import it. The input boat 23 is connected to a rotation angle sensor 12 and a cylinder discrimination sensor 13 via a waveform shaping circuit 29, and is also connected to a terminal IDL (throttle fully closed switch) of a throttle position sensor 4 via a buffer 32. There is. Further, the rotation angle sensor 12 and the cylinder discrimination sensor 13 are connected to the timing generation circuit 2.
It is connected to the CPU 20 via 8. The timing generation circuit 28 generates an interrupt signal for each predetermined crank angle based on the output of the rotation angle sensor 12 and the output of the cylinder discrimination sensor 13, and inputs it to the CPU. In response to this interrupt signal, the CPU stops processing the main routine and executes the interrupt routine even if the main routine is being executed. The output boat 24 is connected to the fuel injection valve 8 via a drive circuit 30 including a down counter. Note that 31 is a clock generation circuit. The ROM stores in advance a control routine program, etc., which will be explained below.

FIG. 7 shows the main routine of this embodiment. In step 100, the engine rotation speed NE calculated from the intake air IQ and the rotation angle sensor output is taken, and in step 102, it is based on the intake air amount Q and the engine rotation speed NE. Then, the basic fuel injection time τ and Ao are calculated. Then, in step 104, the basic fuel injection time τIA is calculated based on the engine cooling water temperature, intake air temperature, etc. The fuel injection time τ is calculated by correcting E.

FIG. 1 shows an interrupt routine executed by an interrupt signal every 50 m5ec generated based on the output of the clock generation circuit 31. In step 106, the throttle valve is located near the fully closed position based on the output of the terminal IDL. It is determined whether or not the throttle fully closed switch, which is turned on when the throttle is turned on, is turned on. If the determination in step 106 is negative, the process proceeds to step 120, and if the determination in step 106 is affirmative, the process proceeds to step 10B. In step 108, the terminal v
The throttle opening degree Vta obtained from the 7 output is compared with the learned value VT6 stored in the backup memory, and the VT
If A>VTG, in step 110, the value obtained by subtracting the learning value VTG from the throttle opening degree VTA and the predetermined value ΔV
TA! Compare with. In step 110, vta v
t. 〉ΔV TA, step 11
In step 4, the learning value (IVyc) is increased by a predetermined value Vc, and when it is determined in step 110 that vta VTG≦ΔV 712, the learning value vttr is increased by vb (in step 1'12, provided that Vb>Vc).

In the next step 116, the learning value v5 updated in steps 112 and 114 and the throttle opening degree V? A
If vte>vt^, the throttle opening degree Vta is set as the learned value VTG in step 118, and if it is determined in step 116 that V0≦vyA, the process proceeds to step 120.

As a result of the above, when V, , >V□, the learning value VTG is increased by a predetermined value Vc or a predetermined value vb and learned to approach the throttle opening degree VtA, as shown in FIG.

Here, when V TA V TG > ΔVtm2171, that is, when the accelerator opening degree is greater than the learning value by a predetermined value, it is considered that the accelerator pedal is being depressed with a fairly high probability, so the learning speed in step 114 is slowed down. The learning value V,. If Δ■ ding^2 ≧vT^-VTG〉O, it is considered that there is a high probability that the accelerator pedal is not depressed, so step 112 is set to be changed from step 114 to Learn at a fast rate and get a learning value of V. is the throttle opening v
I'm trying to get closer to tm.

In the next step 120, the count value t is cleared and the fuel cut permission flag FNC is reset, and in the next step 122, the fuel cut flag Fc is reset,
Return to main routine.

On the other hand, in step 108, if VTA≦vtc (when it is broken), in step 124, the learned value VTG is made smaller by Va (where V, >>V, >Ve),
In step 126, the learning value updated in the step 124 is compared with the throttle opening VTA. Step 126
When it is determined that VTG<VTA, step 128
The throttle opening degree VTA is set to the learned value VtS, and when it is determined in step 126 that VTG≧VTA, the process proceeds to step 130. In step 130, the count value t is incremented, and in the next step 132, the count value t and a predetermined value tc (for example, 100 m5ec-150
m5ec). This predetermined value tc
corresponds to a delay time to prevent torque shock during fuel cut, and when it is determined in step 32 that t<tc, the process proceeds to step 122, and step 132
When it is determined that [≧C], a fuel cut flag Fc is set in step 134.

Here, the throttle opening vT^ is Gaku H (!! V?.

In the following cases, it is considered that the throttle opening degree vra indicates a more correct throttle valve fully closed state, so in step 124, the learned value V. The learned value is updated so that the learned value VfG quickly approaches the throttle opening Vta by making the learning speed faster than in any of the above cases.

As a result of updating the learned values as described above, as shown in FIG.
,.

When , the learning value VtC is increased by Vc and learning is performed at a slow learning speed, and VTA>VTG or VTAV
T! ≦ΔV? At At, the learning value ■,. is increased by vb and learned at a medium learning speed, and Vta≦vi,
In the case of , the throttle opening v0 is set at a fast learning speed.
is learned in such a way that it approaches As a result, the learning value VtC
converges to approach the value of the throttle opening v0 when the throttle valve is fully closed. Also, v0≦v1. The fuel cut flag Fc is set after a time corresponding to the predetermined value 1 has elapsed from the time when the throttle opening degree Vta becomes equal to or less than the learning value V converged as described above.

FIG. 9 shows a fuel injection interrupt routine executed at every predetermined crank angle. In step 136, the engine rotational speed NE and the fuel cut rotational speed N are compared, and if NE≧Nc, the fuel is cut in step 138. A permission flag FNC is set, and in step 140 it is determined whether the fuel cut flag Fc is set. When the fuel cut flag Fc is set, the fuel injection valve 8 is closed to mm in step 142, a fuel cut is executed, and the process returns to the main routine. On the other hand, when it is determined in step 136 that NE < N c , the engine rotational speed NE and the fuel injection return rotational speed Nll are compared in step 14.4. When it is determined in step 144 that N E < N *, the step 148 resets the cut permission flag FNC, and in step 150 a count value corresponding to the fuel injection time τ is entered in the down counter. Fuel injection is performed by opening the fuel injection valve 8 for a time corresponding to the fuel injection time τ, and the process returns to the main routine. - On the other hand, when it is determined in step 144 that NE≧Nll, step 146
It is determined whether the fuel cut permission flag FNC is set or not, and the fuel cut permission flag F is set. If C is set, the process advances to step 140 and the fuel cut permission flag F is set.
If sc has been reset, the process advances to step 150.

As a result of the above, the fuel cut permission flag FNC is set from when the engine speed NE becomes equal to or higher than the fuel cut rotation speed Nc until it becomes less than the fuel return rotation speed N, as shown in FIG. , when the throttle fully closed switch is off or when the throttle fully closed switch is on and v
It is reset when D^>VTG. Then, when the fuel cut permission flag F+tc is set and the fuel cut flag Fc is set, the fuel injection cut is executed.

Next, other embodiments of the present invention will be described. In this embodiment, the fuel cut routine, etc. are the same as those described above, so their illustration is omitted. Only the interrupt routine every 50 m5ec is shown in FIG. 10, and in FIG. 1O, the same parts as in FIG. The explanation will be omitted. Step 1
36, the value obtained by subtracting the learning value v0 from the accelerator opening degree v0 is compared with the minute value Δvta+, and V TA V
? If G > ΔVfa+, proceed to step 120, and V
If y@V y@ ≦ΔV fi+, step 1
If the result is 0 or more, proceed to 30, VTA>V. Even in the case where the difference between Vta and VTG is a small value Δvv as shown in
If it is less than at, it is assumed that the throttle valve is fully closed, and a fuel cut is executed after a predetermined delay time has elapsed.

Above, we explained an example in which the air flow meter is opened and the intake air amount is directly detected to calculate the basic fuel injection time.
The present invention can also be applied to an engine that calculates the basic fuel injection time by indirectly detecting the intake air amount from the intake pipe pressure.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing an interrupt routine every 50m5ec according to an embodiment of the present invention, Fig. 2 is a schematic diagram of an engine equipped with a fuel cut control device to which the invention can be applied, and Fig. 3 is used in this embodiment. A sectional view showing a possible throttle position sensor, FIG. 4 is a circuit diagram showing an electric circuit equivalent to that in FIG. 3, and FIG. 5 is a diagram showing signals of each part output from the throttle position sensor in FIG. 3. FIG. 6 is a block diagram showing details of the control circuit of FIG. 2, FIG. 7 is a flowchart showing the main routine of the above embodiment, and FIG. 8 is a flag FC.
A diagram showing changes in F MC% throttle opening sensor output vra and learned value VA2, etc., FIG. 9 is a flowchart showing the fuel cut routine of the above embodiment, and FIG. 10 is a flow chart of another embodiment of the present invention. A flowchart showing an interrupt routine every 50 rasec, and FIG. 11 is a diagram showing a fuel cut area of the above other embodiment. 4... Throttle position sensor, 7... Fuel pump, 8... Fuel injection valve, 16... Control circuit.

Claims (3)

[Claims] (1) A rotation speed sensor that detects the engine rotation speed, a throttle full-close switch that outputs a throttle full-close signal when the throttle valve is close to fully closed, and a throttle full-close switch that detects the opening degree of the throttle valve and detects the opening degree. a throttle opening sensor that outputs a throttle opening signal according to the throttle opening, a storage means that stores a determination level corresponding to the throttle valve fully closed state, and a throttle opening sensor that outputs a throttle opening signal corresponding to the throttle valve fully closed state; determining means that compares the output with the determination level to determine whether the throttle valve is in a fully closed state, and determines whether or not to stop fuel supply based on the engine rotational speed; A fuel cut control device for an internal combustion engine, comprising: fuel supply stop means for stopping fuel supply based on a determination result of the determination means. (2) The storage means stores, as the determination level, a learning value that is updated to approach the throttle opening sensor output when the throttle fully closed signal is being output. The fuel cut control device for the internal combustion engine described above. (3) When the learned value is larger than the throttle opening sensor output, the learning value is updated at a faster speed than when the learning value is smaller than the throttle opening sensor output. The fuel cut control device for the internal combustion engine described above.