JPH0324582B2 - - Google Patents

Description

Detailed Description of the Invention <Technical Field> The present invention relates to a device for detecting a throttle valve opening based on the output voltage of a throttle valve opening sensor connected and attached to a throttle valve of an internal combustion engine. In particular, high detection accuracy can be maintained by learning and controlling the output voltage value.

<Background Art> In an internal combustion engine equipped with an electronically controlled fuel injection device, the amount of air taken into the cylinder is determined based on the opening degree of a throttle valve installed in the intake passage and the engine speed. Some models are designed to set the basic injection amount, and in this case, a potentiometer-type throttle valve opening sensor is provided that works in conjunction with the throttle valve and outputs a voltage according to the throttle valve opening. There is.

Examples of this type of throttle valve opening sensor include those shown in FIGS. 1 and 2. This device also has a throttle valve switch that detects a predetermined opening range.

To explain this, a bush 2 is fixed to a main body plate 1 as a fixing member, and a guide contact 3 is rotatably supported on the inner peripheral side of the bush 2. A valve shaft end of a throttle valve (not shown) is press-fitted into the hole 3a of the guide contact 3, so that the guide contact 3 rotates in conjunction with the valve shaft. In addition, a ring-shaped rotating member 4 is provided on the outer peripheral side of the bush 2.
is rotatably mounted. A part of the guide contact 3 is provided with an arm 3b that protrudes laterally, and the tip of this arm 3b is located between a pair of screen parts 4a provided on the rotating member 4, so that the guide contact 3 and the rotating member 4 are engaged with each other in the rotational direction. Therefore, when the guide contact 3 rotates in conjunction with the valve shaft, the rotating member 4 also rotates in the same direction. Two brushes 5 are fixed to the rotating member 4, and as these brushes 5 move while sliding on a resistor substrate 6 fixed on the main body plate 1, a valve is actuated in a so-called potentiometer type. The opening degree is continuously detected.

Further, two cam grooves 4b are formed in the rotating member 4, and the free end of the movable piece 7 is guided by these cam grooves 4b. Then, as the rotating member 4 rotates, the contact 7a provided on the movable piece 7 comes into contact with and separates from the contact 8a of the fixed piece 8 at an appropriate rotational position,
By these contact and separation, a predetermined valve opening degree is detected on and off.

The throttle valve opening sensor outputs a voltage V _S corresponding to the throttle valve opening θ to the control unit 9 built in the microcomputer, and the control unit 9 detects the throttle valve opening θ (0≦θ≦90°). ) is calculated from the throttle valve opening sensor output characteristic equation θ=B×( _AVS ), and as described above, the basic injection amount is calculated from the throttle valve opening θ and the engine function N. After making corrections based on other operating conditions, the injector 10 is driven by outputting an injection pulse having a pulse width corresponding to the corrected injection amount to inject the amount of fuel.

By the way, the output characteristics of the throttle valve opening sensor vary from the maximum value when the throttle valve is fully closed (0°) to the maximum value when the throttle valve is fully open (90°), as shown in the above equation.
is set to change linearly between the minimum values of .

However, in reality, errors occur due to variations in the linearity of the throttle valve and the throttle valve opening sensor itself, resulting in a large error rate especially on the low opening side, which has a large impact on injection control, etc. . The error changes, for example, during operation due to differences in thermal expansion coefficients during the warm-up process and subsequent temperature changes, and also changes over time.

For example, if there is a ±0.2V variation in V _S , θ
This results in a variation of ±3.6°, but even a slight difference in the opening at low openings, especially near fully closed, causes a large change in the intake air flow rate, resulting in a significant drop in injection quantity control accuracy. I was getting used to it.

In this case, A is set as the value of V _S when the throttle valve is fully closed in the output characteristic of the throttle valve opening sensor θ = B × (A - V _S ), but as mentioned above, V The biggest cause of error is that A is set to a constant value despite the large variation in _S. In addition, B (constant of proportionality) caused by variations in the characteristics of the sensor itself, etc.
Variations in the values also cause errors. However, compared to the error caused by A, the degree of error generated is quite small. This is because A depends on the setting error (installation error) of the throttle valve and sensor and the magnitude of the resistance value variation on the fully closed side of the potentiometer.

<Purpose of the Invention> The present invention was made in view of these conventional problems, and it absorbs errors in the output characteristics by learning and controlling the output state of the throttle valve, and can always open the throttle valve with high precision. An object of the present invention is to provide a throttle opening degree detection device capable of detecting the degree of throttle opening.

<Summary of the Invention> Therefore, the first aspect of the present invention is to provide a throttle valve opening sensor that outputs a voltage signal according to the throttle valve opening as shown by the solid line in FIG. In a throttle valve opening detection device equipped with a θ calculation means that calculates θ from the output voltage characteristic equation θ=B×( _AVS ) of the throttle valve opening sensor, the means for detecting that the throttle valve is fully closed when the engine speed is controlled to a target speed for a predetermined period of time by an idle control valve that controls an air flow rate that bypasses the throttle valve when the throttle valve is closed; means for updating the value of A in the voltage characteristic equation to a value corrected based on the output voltage value from the throttle valve opening sensor each time the throttle valve is fully closed by the throttle valve fully closed detection means; The configuration includes the following.

In addition to the configuration of the first invention, a second invention provides a structure in which, as shown by the dotted line in FIG. A means for detecting that the valve is fully open, and an output voltage value from the throttle valve opening sensor and and means for updating the value of A to a corrected value based on the updated value of A.

<Example> The present invention will be described below based on an example shown in the drawings.

A throttle valve opening sensor 14 similar to that shown in FIGS. 1 and 2 is attached to the end of the valve shaft of the throttle valve 13 installed in the intake passage 12 of the internal combustion engine 11. This signal is input to a control unit 15 containing a microcomputer. The throttle valve opening sensor 14 includes a throttle valve 13.
A fully closed throttle valve switch that turns on when the valve is fully closed is integrated. The control unit 15 includes a rotation speed sensor 1 for detecting the engine rotation speed of the throttle valve opening sensor 14.
6. A signal from a water temperature sensor 17 or the like that detects the engine cooling water temperature is input.

On the other hand, an injector 18 is attached to the intake passage 12, and a bypass passage 19 is formed to bypass the throttle valve 13. An electromagnetic idle control valve 20 is interposed in the bypass passage 19.

The control unit 15 then controls the injector 18 based on the signals from the various sensors.
A drive pulse is output to control the fuel injection amount, and a drive pulse is output to the idle control valve 20 to control the idle rotation speed (ISC). The value of the constant A of the output characteristic equation θ=B×( _AVS ) of the throttle valve opening sensor 14 for calculating the throttle angle is corrected and updated.

Next, a routine for controlling the fuel injection amount by the control unit 15 will be explained with reference to the flowchart shown in FIG. First, in S1, the output voltage signal V _S from the throttle valve opening sensor 14 is converted from analog to digital and read in. In S2, the throttle valve opening θ is calculated by the formula θ = B × (A - V _S ). . Next, in S3, the rotation speed N is detected from the rotation speed sensor 16.
After reading the signal, the basic injection amount Tp is calculated based on θ and N in S4, the injection amount is corrected based on water temperature, etc. in S4, and injection with a pulse width corresponding to the corrected injection amount is performed in S5. A pulse is output to the injector 18 to drive it and inject a predetermined amount of fuel.

Then, the same control unit 15
The ISC and the A value updating routine performed during the ISC will be explained according to the flowchart of FIG.

This routine is performed when the throttle valve fully closed switch assembled integrally with the throttle valve opening sensor 14 is turned on, that is, when the throttle valve is fully closed, and the vehicle is in a low speed state where the vehicle speed is below a predetermined value. , or the gear shift position is in neutral (ISC condition). In S11, the target rotation speed Ns is calculated according to the water temperature, etc., and in S12, the actual rotation speed is calculated. Compare with N. When Ns and N match within the allowable range, the valve opening duty of the idle control valve 20 is maintained at the current state in S13, and when Ns>N, the valve opening duty is similarly increased in S14, and Ns<N In this case, reduce the valve opening duty in S15 as well. In this way, the amount of intake air flowing through the bypass passage 19 is increased or decreased, and the injection amount is controlled according to the opening degree of the idle control valve 20 (this routine is omitted), thereby adjusting the actual rotation speed N to the target rotation speed Ns. I am trying to control the distance to get closer. And for S13 continue
In S16, it is determined whether the predetermined time has elapsed in that state (Ns = N), and if it has, Vs is read in S17, and in S18, the weighted average value _S is subtracted from the Vs read in the previous routine. Then, in S19, this V _S is calculated using the calculation formula θ=B×(A
-V _S ) as the value of A.

In this way, even if the output voltage Vs varies due to variations in the installation position of the throttle valve opening sensor 14 or changes over time, the actual output when the throttle valve is fully closed can be adjusted by repeating the routine several times. Since the value of A is corrected and updated each time based on the voltage, the throttle valve opening calculated by θ = B × (A - V _S ) absorbs the above-mentioned variations and always maintains the true value. It is determined as a small value with a small error close to . In addition, errors that change due to differences in thermal expansion coefficients due to temperature changes during operation are also
By learning the value of , the throttle valve opening can be kept close to the true value.

In this way, the detection of the throttle valve opening degree is improved, and the detection error rate is significantly reduced, especially on the low opening side, thereby increasing the accuracy of injection amount control based on the throttle valve opening degree as a value corresponding to the intake air amount. can be significantly increased. Furthermore, even if the accuracy of the throttle valve opening sensor itself is somewhat low during manufacture, high detection accuracy of the throttle valve opening can be obtained just by performing the above-mentioned learning control of the value of A several times. Costs can also be reduced.

In addition, as a configuration according to the present invention, when the fully closed throttle valve 13 is detected from a signal other than the signal from the throttle valve opening sensor 14, not only the throttle fully closed switch is turned on, but also when Ns=N has elapsed for a predetermined period of time. The reason for this is that the output state from the throttle valve opening sensor becomes more stable if a certain amount of time elapses after the throttle valve is fully closed. In addition, the latest value of V _S when the throttle valve is fully closed is not updated directly as the value of A, but is updated as a weighted average value _S with the previous value, because of the impact when operating the throttle valve. This is to absorb variations in output voltage caused by such factors.

FIG. 7 shows an embodiment of the second invention, and FIG.
In addition to the configuration shown in the figure, as a means for detecting the fully open state of the throttle valve, the boost pressure on the downstream side of the throttle valve 13 in the intake passage 12 is detected, and when the throttle valve 13 is fully opened, the boost pressure becomes atmospheric pressure. A pressure switch 21 is provided which turns on when the pressure exceeds a set value close to .
The control unit 22 performs the routine shown in FIGS. 5 and 6, and also performs the following with the throttle valve 13 fully open based on the signal from the pressure switch 21: θ=B×( A routine is performed to correct and update the value of B in A-V _S ).

This routine will be explained below with reference to the flowchart of FIG. In S20, it is determined whether the period rotational speed N is equal to or higher than a high-speed predetermined rotational speed (for example, 6000 rpm) N _H or not. If the number of revolutions is less than a predetermined number, this routine ends, but if the number of revolutions is greater than the predetermined number, the routine proceeds to step 21. Pressure switch 21 is activated by S21.
Determine whether it is ON or not, and when it is ON,
In other words, when the throttle valve is fully open and stable,
In S22, it is determined whether this state has passed for a predetermined period of time. If the predetermined time has elapsed, the output voltage V _S from the throttle valve opening sensor 14 is read in S23, and the weighted average value _s2 of this V _S value with the V _S read in the previous routine is calculated in S24. do. Next, in S25 _{, θ 0 /} ( _S1 −
Vs ₂ ). However, θ ₀ is the angle at which the throttle valve can rotate, and is generally 90°. Then, in S26, the calculation result θ ₀ / _S1 − _S2 ) is updated as the value of B. Incidentally, since there are few opportunities to learn the value of B, the weight of the latest value is made larger than the weight of the weighted average value in the calculation of the weighted average so that correction can be made with a good response even when the number of times of learning is small.

In this way, the value of the proportionality constant B in the output characteristic equation θ=B×(A- _VS ) of the throttle valve opening sensor 14 is controlled by learning the output V _S when the throttle valve is fully closed and when the throttle valve is fully open. By updating the correction,
In particular, variations in the linearity of the sensor itself can be sufficiently absorbed to further improve the detection accuracy of the throttle valve opening.

<Effects of the Invention> As explained above, according to the present invention, the output characteristic equation of the throttle valve opening sensor θ=B×(A−
Since the value of A at V _S ) is configured to accurately detect the fully closed state of the throttle valve and correct and update it using learning control, variations in the installation position of the throttle valve opening sensor and temperature changes during operation can be avoided. Errors in detecting the throttle valve opening due to changes over time or variations in the characteristics of the sensor itself can be eliminated as much as possible, the detection accuracy can be significantly improved, and the state can be maintained stably at all times.
Furthermore, as a result, the cost of the sensor itself can be reduced, and in systems that control the injection amount based on the throttle opening, the accuracy of the injection amount control, especially on the low opening side, can be significantly improved. Further, in the second aspect of the invention, the above-mentioned effects can be further enhanced in the second aspect of the invention, in which the value of B is also configured to detect the fully closed state of the throttle valve with high precision and to correct and update it through learning control.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the configuration of a general throttle valve opening sensor, and Fig. 2 is a plan view showing the configuration of a general throttle valve opening sensor.
3 is a block diagram showing the configuration of the present invention, FIG. 4 is a configuration diagram showing an embodiment of the first invention, and FIG. 5 is a flowchart showing an injection amount control routine in the same embodiment. Chart, Figure 6 is the same
A flowchart showing the ISC and A value update routine, FIG. 7 is a configuration diagram showing an embodiment of the second invention,
FIG. 8 is a flowchart showing the B value update routine in the same embodiment. 11... Internal combustion engine, 12... Intake passage, 13...
... Throttle valve, 14... Throttle valve opening sensor, 15, 22... Control unit, 16... Rotation speed sensor, 17... Water temperature sensor, 20... Idle control valve.

Claims (1)

[Scope of Claims] 1. Connected to the valve shaft end of a throttle valve installed in an intake passage of an internal combustion engine, and connected to the rotation of the throttle valve to generate a voltage signal corresponding to the opening degree of the throttle valve. The throttle valve opening sensor outputs the throttle valve opening θ, and the output voltage characteristic equation of the throttle valve opening sensor θ=B×
In a throttle valve opening detection device equipped with means for calculating and calculating from ( _AV means for detecting that the throttle valve is in a fully closed state when the throttle valve is controlled to a target rotational speed for a predetermined period of time; and A in the output voltage characteristic equation.
means for updating the value to a value corrected based on the output voltage value from the throttle valve opening sensor each time the throttle valve is fully closed by the throttle valve fully closed detection means. A throttle valve opening detection device featuring: 2. A throttle valve opening sensor that is connected to the valve shaft end of a throttle valve installed in the intake passage of an internal combustion engine and outputs a voltage signal corresponding to the throttle valve opening in conjunction with rotation of the throttle valve. and the throttle valve opening θ is expressed as the throttle valve opening sensor output voltage characteristic equation θ=B×
In a throttle valve opening detection device equipped with means for calculating and calculating from ( _AV means for detecting that the throttle valve is in a fully closed state when the number of rotations is controlled to the target rotational speed for a predetermined period of time; and A in the output voltage characteristic equation.
means for updating the value of the throttle valve to a value corrected based on the output voltage value from the throttle valve opening sensor each time the throttle valve is fully closed by the throttle valve fully closed detection means; means for detecting that the throttle valve is fully open when the intake pressure continues to be at or above a predetermined value under operating conditions for a predetermined time or more; A throttle valve opening detecting device comprising means for updating the value to a corrected value based on the output voltage value from the valve opening sensor and the updated value of A.