JPH0735737B2 - Throttle valve fully closed position detection device - Google Patents

Description

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 fuel supply during deceleration.

[Conventional technology]

Conventionally, an internal combustion engine provided with a fuel cut control device that injects fuel based on a basic fuel injection time determined based on an engine speed and an engine load (intake air amount or intake pipe pressure) and stops fuel injection during deceleration The institution is known. This fuel cut control device judges whether to decelerate based on the on / off state of the throttle fully closed switch that is turned on when the throttle valve is located near the fully closed state, and whether to stop fuel injection based on the engine speed. When the throttle fully closed switch is on and the engine speed is higher than the fuel cut speed, fuel injection is stopped and fuel cut is executed.When the throttle fully closed switch is on and the engine speed is The fuel injection is restored when the rotation speed becomes lower than the fuel injection return rotation speed lower than the fuel cut rotation speed. As a technique related to the fuel cut, there is a technique described in JP-A-56-92332.

[Problems to be solved by the invention]

However, the slot opening is typically 1.5 ± 0.5
Since there is a tolerance of less than °, the throttle valve fully closed switch may output a throttle valve fully closed signal (ON signal) even when the throttle valve is not fully closed. Therefore, when operating in the 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, the fuel cut is executed and the driver intends to decelerate. Even if it is not, there is a problem that the speed is reduced and the feeling deteriorates. Especially in a large internal combustion engine, the diameter of the throttle valve is large due to the large bore diameter, while the tolerance is almost the same as that of a small internal combustion engine, so the throttle fully closed switch is turned on even when the intake air amount is large. Therefore, the above tendency becomes remarkable.

The present invention has been made to solve the above problems, and improves the detection accuracy when the throttle valve is fully closed to prevent the fuel cut from being executed during operation in an extremely low load range. The purpose is to provide a device.

[Means for solving problems]

To achieve the above object, the present invention provides a rotation speed sensor that detects an engine rotation speed, a throttle fully closed switch that outputs a throttle fully closed signal when the throttle valve is positioned near full closure, and an opening of the throttle valve. And a storage means for storing a determination level corresponding to a fully closed state of the throttle valve, and the throttle fully closed signal. Sometimes, the output of the throttle opening sensor is compared with the determination level to determine whether the throttle valve is in the fully closed state, and whether to stop the fuel supply based on the engine speed. And a fuel supply stopping means for stopping the fuel supply based on the result of the judgment by the judging means.

[Action]

According to the present invention, the engine speed is detected by the rotation speed sensor, the slot opening is detected by the slot opening sensor, the slot opening signal corresponding to the slot opening is output, and the slot valve is fully closed. The throttle fully closed signal is output from the throttle fully closed switch when it is located in the vicinity. The storage means stores the determination level corresponding to the fully closed state of the throttle valve. In this storage means, when the throttle fully closed signal is output, the learning value updated so as to approach the throttle opening sensor output is stored as the determination level, and when the learning value is larger than the throttle opening sensor output. The speed at which the learning value is updated is stored faster than when the learning value is smaller than the throttle opening sensor output. The determination means compares the output of the throttle opening sensor with the determination level to determine whether the throttle valve is in the fully closed state. Whether or not the throttle valve is in the fully closed state can be determined by determining whether or not the output of the throttle opening sensor is below the determination level, and when this determination is affirmative, the throttle valve is fully closed. It is determined to be in the closed state. Further, when it is determined that the throttle valve is in the fully closed state, the determining means determines whether to stop the fuel supply based on the engine speed, and the engine speed becomes equal to or higher than the fuel cut speed. When the fuel cut condition is satisfied, it is determined that the fuel cut condition is satisfied. The fuel supply stopping means stops the fuel supply when the determining means determines that the fuel cut condition is satisfied.

As described above, according to the present invention, the determination level corresponding to the fully closed state of the throttle valve is compared with the output of the throttle opening sensor to determine whether or not the throttle valve is in the fully closed state. Even if there is a tolerance in the opening, it is possible to accurately detect the fully closed state of the throttle valve, which prevents the fuel cut from being executed during operation in an extremely low load range. can do.

Here, the accurate detection of the fully closed state of the throttle valve can be achieved by simply comparing the output of the throttle opening sensor with the above-mentioned determination level. In such cases as well, there is a risk that the throttle valve is determined to be fully closed and the fuel cut is executed during normal operation.

〔The invention's effect〕

According to the present invention, when the learned value is larger than the output of the throttle opening sensor (learned value> current value), there is a high possibility that the throttle valve is fully closed. Aiming at improvement, when the learned value is smaller than the throttle opening sensor output (learned value <current value), the update speed is set lower than that to reduce the possibility that the learned value is updated abnormally. The effect of is obtained.

[Description of mode]

The present invention can take the following aspects in carrying out the invention. In the first mode, a learning value updated so as to approach the output of the throttle opening sensor when the throttle fully closed signal is output is stored as the determination level.

According to this aspect, since the determination level is learned so as to approach the throttle opening sensor output, even if there is a tolerance in the throttle opening, the determination level is learned to converge to the value in the fully closed state of the throttle valve. It is possible to accurately detect the fully closed state of the throttle valve.

In a second aspect, in the first aspect, the speed at which the learned value is updated when the learned value is larger than the throttle opening sensor output than when the learned value is smaller than the throttle opening sensor output. It is intended to speed up.

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

A third mode is to compare a difference obtained by subtracting the learning value from the throttle opening sensor output with a predetermined value when the learning value is smaller than the throttle opening sensor output, and to compare the difference when the difference is larger than the predetermined value. The speed of updating the learning value is made slower 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 at a throttle opening larger than the throttle fully closed state due to the tolerance,
Since the learned value is updated gently, 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 (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 an air flow meter 2 for detecting the amount of intake air is provided downstream of the air cleaner 1. The air flow meter 2 is provided with a compensation plate rotatably provided in the damping chamber, a media ring plate connected to the media volume plate, and a potentiometer for detecting the opening of the media plate. . Therefore, the intake air amount can be obtained 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 slot 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 combustion chamber of the engine via the intake manifold 5 and the intake port. A fuel injection valve (fuel injector) 8 is attached to each cylinder or each cylinder group so as to project into the intake manifold 5. The fuel injection valve 8 is connected to the fuel tank 6 via the fuel pump 7, and is configured to supply fuel of a predetermined pressure to the fuel injection valve 8. Therefore, by opening the fuel injection valve 8 for a predetermined time, a quantity of fuel corresponding to this time is injected.

The combustion chamber of the engine is connected to a catalyst device (not shown) filled with a three-way catalyst via an exhaust port and an exhaust manifold. This exhaust manifold is equipped with an O ₂ sensor that outputs a signal determined based on the stoichiometric air-fuel ratio. A cooling water temperature sensor 15 is attached to the engine block so as to penetrate the block and project into the water jacket.
The 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 project into the combustion chamber.
The ignition 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. A cylinder discrimination sensor 13 and a rotation angle sensor 12, each of which is composed of a signal rotor fixed to the distributor viewer and a pick-up fixed to the distributor housing, are mounted in the distributor 11. . In the case of a 6-cylinder engine, the cylinder discrimination sensor 13 is 720 ° C.
A cylinder discrimination signal is output for each A, and the rotation angle sensor 12 is 30 ° CA.
An engine speed signal is output every time. The slot position sensor 4, as shown in FIG. 3, has a slot contact detection movable contact 18 and a slot fully closed detection movable contact 19 mounted on a plate that rotates in conjunction with the slot valve 3. Is equipped with. The movable contact 18 for detecting the throttle opening is arranged so as to slide on the resistor 20A and the resistor 21A on the arc printed in parallel on the board, and the movable contact 19 for detecting the fully closed slot is on the board. It is arranged so as to slide on the printed conductors 22A and 23A. One end of the resistor 20A has a terminal V connected to the power supply (5V)
The resistor 20A is electrically connected to c, and the other end of the resistor 20A is electrically connected to the grounded terminal E ₁ . Further, one end of the resistor 21A is connected to the terminal V _T , and one end of the conductor 23A is connected to the terminal IDL. The conductor 22A is electrically connected to the terminal E ₁ .

The slot position sensor 4 configured as described above.
The equivalent circuit of is shown in FIG. The slot contact detection movable contact 18 and the resistors 20A, 21A act as a slot opening sensor SN, and the slot fully closed detection movable contact
19 and the conductors 22A and 23A act as a slot fully closed switch SW. The terminal V _T output and terminal IDL output are shown in FIG. Therefore, the terminal IDL outputs a signal that is turned on when the throttle valve is located near the fully closed position, and the terminal V _T outputs a throttle opening signal proportional to the throttle opening.

Further, as shown in FIG. 6, the control unit 16 includes a central processing unit (CPU) 20, a read only memory (ROM) 20, a random access memory (RAM) 22 having a back-up memory, and an input. It is configured to include a port 23, an output port 24, and a bus 25 such as a data bus or a control bus that connects these ports. The CPU 20, analog - to-digital (A / D) air flow meter 2 via the converter 26 and multiplexer 27, the cooling water temperature sensor 15 (not shown) together with the terminal V _T of Ro Tsu torr positive Chillon sensor 4 is connected It is connected. The CPU 20 controls the multiplexer 27 to sequentially input the output of the air flow meter 2 and the terminal V _T output of the slot position sensor 4 (the output of the slot opening sensor) and activate the A / D converter 26 to input the input signal. It is converted into a digital signal and captured. A rotation angle sensor 12 and a cylinder discrimination sensor 13 are connected to the input port 23 via a waveform shaping circuit 29.
And the terminal IDL (throttle fully closed switch) of the slot position sensor 4 is connected via the buffer 32. Further, the rotation angle sensor 12 and the cylinder discrimination sensor 13 are connected to the CPU 20 via a timing generation circuit 28. 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 the interrupt signal to the CPU.
With this interrupt signal, the CPU suspends the processing of the main routine and executes the interrupt routine even while the main routine is being executed. The output port 24 is connected to the fuel injection valve 8 via a drive circuit 30 including a down counter. Reference numeral 31 is a clock generation circuit. RO above
A program for a control routine described below is stored in M in advance.

FIG. 7 shows the main routine of this embodiment. Therefore, in step 100, the engine speed NE calculated from the intake air amount Q and the output of the rotation angle sensor is taken in.
At, the basic fuel injection time τ _BASE is calculated based on the intake air amount Q and the engine speed NE. Then, in step 104, the basic fuel injection time τ _BASE is corrected based on the engine cooling water temperature, the intake air temperature, etc. to calculate the fuel injection time τ.

FIG. 1 shows an interrupt routine executed by an interrupt signal every 50 msec generated based on the output of the clock generation circuit 31. At 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 that 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 108. At step 108, the throttle opening V _TA obtained from the terminal V _T output is compared with the learning value V _TG stored in the backup memory, and if V _TA > V _TG , at step 110 the learning value from the slot opening V _{TA is} learned. V _TG subtracted value and predetermined value Δ
Compare with V _TA2 . If it is determined in step 110 that V _TA −V _TG > ΔV _TA2 , the learning value V _TG is increased by a predetermined value Vc in step 114, and if it is determined in step 110 that V _TA −V _TG ≦ ΔV _TA2 , the step is determined. At 112, the learning value V _TG is increased by Vb. However, Vb> Vc. In the next step 116, the learning value V _TG updated in steps 112 and 114 is compared with the throttle opening V _TA, and if V _TG > V _TA , step 1
At 18, the throttle opening V _TA is set to the learning value V _TG, and when it is determined at step 116 that V _TG ≦ V _TA , the routine proceeds to step 120.

As a result of the above, when V _TA > V _TG , as shown in FIG. 8, the learning value V _TG is increased by the predetermined value Vc or the predetermined value Vb and learned so as to approach the throttle opening V _TA .

Here, when V _TA −V _TG > ΔV _TA2 , that is, when the accelerator opening is larger than the learning value by a predetermined value or more, it is considered that the accelerator pedal is depressed with a fairly high probability, so the learning speed in step 114 is considered. So that the learning value V _TG is not updated significantly. On the other hand, ΔV _TA2 ≧ V _TA −V _TG
When> 0, it is considered highly likely that the accelerator pedal is not depressed, so at step 112, step 1
The learning value V _TG is learned at a speed faster than 14 and the throttle opening V is
_{I try} to get closer to the _TA .

At the next step 120, the count value t is cleared, the fuel cut permission flag F _NC is reset, the fuel cut flag Fc is reset at the next step 122, and the process returns to the main routine.

On the other hand, when it is determined that V _TA ≤V _TG in step 108, the learning value V _{TG is set} to Va (where Va>
>Vb> Vc), and the learning value updated in step 124 is compared with the throttle opening V _TA in step 126. The Surotsutoru opening V _TA in step 128 when it is determined that V _TG <V _TA and learning value V _TG in step 126, V _TG in step 126
When it is determined that ≧ V _TA , the routine 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, 1
Value corresponding to 00msec to 150msec). This predetermined value tc corresponds to a delay time for preventing torque shock at the time of fuel cut. When it is judged at step 132 that t <tc, the routine proceeds to step 122 and at step 132 t.
When it is determined that .gtoreq.tc, the fuel cut flag Fc is set at step 134.

Here, when the throttle opening V _TA is less than or equal to the learning value V _TG , it is considered that the throttle opening V _TA indicates a more correct throttle valve fully closed state, so the learning value V _TG is learned in step 124 above. The learning value is updated so that the learning speed V _TG becomes faster than any of the above cases and the learning value V _TG quickly approaches the throttle opening V _TA .

As a result of updating the learning value as described above, the learning value V _TG is _satisfied when V _TA > V _TG and V _TA −V _TG > ΔV _TA2 as shown in FIG.
Is increased by Vc and learned at a slow learning speed, V _TA > V
_TG and V _TA −V _TG ≦ ΔV _TA2 , the learning value V _TG is increased by Vb to learn at a medium learning speed, and when V _TA ≦ V _TG , the learning value is fast and the slot opening V Learned to approach _TA . As a result, the learned value V _TG converges so as to approach the value of the throttle opening V _{TA when} the throttle valve is fully closed. Further, the fuel cut flag Fc is set after the time corresponding to the predetermined value tc has passed from the time when V _TA ≦ V _TG , that is, the time when the throttle opening V _TA becomes equal to or less than the learned value V _G converged as described above. It

FIG. 9 shows a fuel injection interruption routine executed at every predetermined crank angle. At step 136, the engine speed NE and the fuel cut speed Nc are compared, and NE ≧
If Nc, at step 138, fuel cut permission flag F _NC
The fuel cut flag Fc at step 140.
Judge whether or not is set. When the fuel cut flag Fc is set, the closed state of the fuel injection valve 8 is continued in step 142 to execute the fuel cut, and the process returns to the main routine. On the other hand, step 136 NE
If it is determined to be <Nc, the engine speed NE and the fuel injection return speed N _R are compared in step 144. When NE <N _R is determined in step 144, the fuel cut permission flag F _NC is reset in step 148, and in step 150, the count value corresponding to the fuel injection time τ is set in the down counter and the fuel injection time τ is set.
By opening the fuel injection valve 8 for a time corresponding to, fuel injection is executed and the process returns to the main routine. on the other hand,
When it is determined that NE ≧ N _R in step 144, the process proceeds to the fuel Katsuhito permission flag F _NC is determined whether it is excisional fuel Katsuhito permission flag F _NC is step 140 if it is excisional at step 146, the fuel Cut permission flag F
_{If NC} is reset, proceed to step 150.

As a result, as shown in FIG. 8, the fuel cut permission flag F _NC indicates that the engine speed NE is equal to the fuel cut speed Nc.
After the above, it is set until the fuel return rotational speed becomes less than N _R, but it is reset when the throttle fully closed switch is off or when the throttle fully closed switch is on and V _TA > V _TG . Then, when the fuel cut permission flag F _NC is set and the fuel cut flag Fc is set, the fuel injection cut is executed.

Next, another embodiment of the present invention will be described. In the present embodiment, the fuel cut routine and the like are the same as those described above, so the illustration thereof is omitted. Only the interrupt routine every 50 msec is shown in FIG. 10. In FIG. 10, the same parts as those in FIG. The description is omitted. At step 136, a value obtained by subtracting the learning value V _TG from the accelerator opening V _TA and a minute value ΔV
Comparing the _TA1, the process proceeds to V _TA -V _TG> ΔV _TA1 if step 120, the process proceeds to V _TA -V _TG ≦ ΔV _TA1 if step 130. As a result, even if V _TA > V _TG , as shown in Fig. 11, V _TA
If the difference between V _TG and V _TG is a small value ΔV _TA1 or less, it is considered that the throttle valve is fully closed, and the fuel cut is executed after a lapse of a predetermined delay time.

In the above, 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 is explained.
The present invention can also be applied to an engine that indirectly detects the intake air amount from the intake pipe pressure and calculates the basic fuel injection time.

[Brief description of drawings]

FIG. 1 is a flow chart showing an interrupt routine every 50 msec of one embodiment of the present invention, FIG. 2 is a schematic view of an engine equipped with a fuel cut control device to which the present invention is applicable, and FIG. 3 is used in this embodiment. FIG. 4 is a sectional view showing a possible slot position sensor, FIG. 4 is a circuit diagram showing an electric circuit equivalent to FIG. 3, and FIG. 5 shows signals of respective parts output from the slot position sensor shown in FIG. FIG. 6 is a block diagram showing the details of the control circuit of FIG. 2, FIG. 7 is a flow chart showing the main routine of the above embodiment, and FIG. 8 is a flag Fc, F _NC , the throttle opening sensor output. A diagram showing changes in V _TA and learning value V _TG, etc., FIG. 9 is a flow chart showing a fuel cut routine of the above embodiment, and FIG. 10 is a flow chart showing an interrupt routine every 50 msec of another embodiment of the present invention. FIG. 11 is a diagram showing the fuel cutting area of the other embodiment. is there. 4 ... Slot position sensor, 7 ... Fuel pump, 8 ... Fuel injection valve, 16 ... Control circuit.

Claims (1)

[Claims] 1. A throttle fully closed switch for outputting a throttle fully closed signal when the throttle valve is positioned near the fully closed state, and an opening of the throttle valve is detected to output a throttle opening signal corresponding to the opening. And a throttle opening sensor that stores a learning value of the throttle opening sensor output that is updated so as to approach the throttle opening sensor output when the throttle fully closed signal is being output, and the learning is performed. When the value is larger than the output of the throttle opening sensor, the learning value is stored at a higher speed to update the learning value than when the learning value is smaller than the output of the throttle opening sensor, and the throttle fully closed signal is output. The throttle opening sensor output is compared with the determination level while the throttle valve is fully closed. Fully closed position detecting apparatus of a throttle valve comprising a determining means for determining Luke, the.