JPH0236768B2 - NAINENKIKANNONENRYOKYOKYUSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel supply system for an internal combustion engine that uses an air supply amount control method and is configured so that the flow rate of air to be supplied to the internal combustion engine can be controlled by an actuator operated by a computer.

Conventionally, the supply of air to the internal combustion engine of automobiles, etc. was controlled by opening and closing a throttle valve mechanically connected to the accelerator pedal via a transmission mechanism when the driver depressed the accelerator pedal. . Also, the throttle valve can be electric, pneumatic,
The movement of the accelerator pedal is electrically detected so that it can be opened and closed by a hydraulic actuator, and this detection signal is processed by an electronic control unit such as a computer in consideration of the engine state.
It is also conceivable to operate the actuator in such a way that the necessary air flow rate for the internal combustion engine is obtained. Through this control mechanism, the rotational speed is maintained constant during idling, and the air-fuel ratio (A/
Some methods have been put into practical use, such as keeping the F value constant. Furthermore, attempts have been made to similarly control the air supply amount under all operating conditions. However, in conventional fuel supply systems that use air supply amount control, the air flow rate passing through a throttle valve equipped with an actuator is determined by an air detector (for example, an air flow sensor) or by actual measurement of the air amount based on the operating conditions of the internal combustion engine. It can be calculated and controlled from the value. However, air flow sensors for automobiles tend to be difficult to manufacture and have complex structures because they require high measurement accuracy, resulting in high manufacturing costs.Furthermore, they are susceptible to the effects of the engine's intake system, so Since it is placed away from the main body, it reduces responsiveness, creates resistance in the air flow path, causes pressure loss, occupies a large amount of space, and increases the weight of the vehicle. Ta. On the other hand, the method of determining the air flow rate by comparing the actual values from the operating conditions of the internal combustion engine, such as the intake manifold pressure and engine speed, does not require an air flow sensor, which has various drawbacks, but due to differences in the characteristics of the internal combustion engine, Because it is directly affected, it is greatly affected by variations in engine characteristics and changes over time. For example, changes over time can cause the air flow path to change under the same engine speed and intake manifold pressure, so it is important to always maintain high accuracy. Difficult to adjust. Furthermore, it is extremely problematic in practical terms because it is necessary to accumulate and manage an extremely large amount of measured data according to the characteristics set according to the type and purpose of the engine. Furthermore, when adjusting the amount of air in A/F control, the servo mechanism increases or decreases the opening of the throttle valve so that the output value of the exhaust gas sensor reaches the target value, so there is no need to detect the adjusted amount of air. No, but
This is because the amount of air that is adjusted is small and does not bring about a change in the engine output that can be felt by the driver, and is essentially different from controlling the amount of air for controlling the engine output.

In view of the above points, the present invention provides an air supply amount control type fuel that does not require an air flow sensor, has a simple structure, can be manufactured at low cost, and can be easily changed to high-speed control of air amount or other control. The present invention is to provide a supply device, which will be explained below with reference to an embodiment shown in the drawings. 1 is an accelerator pedal, 2 is a sensor that detects the position of the accelerator pedal 1, and 3 is a sensor 2 that detects the position of the accelerator pedal. A computer 6 is supplied into the engine 4, into which electric signals generated according to the position of the engine 1 are inputted, and signals from a plurality of sensors 5 provided in the engine 4 for detecting various states are inputted. An air control actuator 7 controls air, and a fuel control actuator 7 controls fuel supplied into the engine 4. 2 to 4 show details of the air control actuator 6 according to the present invention, in which 11 is a throttle valve body, 12 is fixed to a shaft 13 rotatably supported within the throttle valve body 11. A gear 16 that meshes with a gear 15 fixed to the shaft of a stepping motor 14 is attached to one end of the shaft 13, and the valve plate 12 is adjusted to a predetermined opening degree by the operation of the stepping motor 14. It is becoming possible to do so. In addition, the opening degree of the valve plate 12 (the third
The opening degree at position A in the figure) θ is the angle from position B to position A, with the reference opening degree being 0°, which is the position immediately before the valve is fully opened (FIG. 3B). Therefore, at the fully open position C, θ _nax . At θ=0°, ie at position B, the air flow rate is less than the minimum air flow rate required by the engine. Further, the reference opening position B is determined by the lever 17 attached to the gear 16 as shown in FIG.
is detected by contacting the switch 18,
Or it can be detected by an absolute position sensor built into the motor or throttle shaft.
In the case of FIG. 4, the reference opening position B can be adjusted by a stop screw 17a attached to the lever 17. 19 is a pressure detection port provided on the upstream side of the valve plate 12 of the valve body 11; 20 is the valve plate 12 of the valve body 11;
A pressure detection port 21 provided on the downstream side of the pressure detection port 21 is a differential pressure sensor that is connected to the two pressure detection ports 19 and 20 by a pressure transmission pipe, detects the pressure difference ΔP, and outputs the detected pressure difference ΔP to the computer 3. The air flow characteristics of the above-mentioned throttle valve are shown in FIG. 5, where the horizontal axis is the air flow rate QA, and the vertical axis is the pressure difference ΔP, each plotted on a logarithmic scale. in this case,
The reference opening position is inclined at 5° with respect to the plane perpendicular to the flow path, and 0°≦85°. Also, the valve plate 12
The opening θ is determined by the number of pulses from a reference point for driving the stepping motor 14 (that is, the reference opening B of the valve plate 12), and an opening sensor (not shown) that counts this number of pulses is used. It is then detected.

By the way, the air flow characteristics shown in Fig. 5 are stored in the computer 3, but the values of ΔP, QA, and θ are analog and the combinations thereof are infinite, so it is almost impossible to store these combinations. . Therefore, the computer 3 digitally measures ΔP and QA as shown in FIG.
Values of θ corresponding to combinations of QA values are stored, and this is hereinafter referred to as a θ map. The value of θ for a combination of ΔP and QA that is not in this θ map can be calculated by interpolation. That is, when the target ΔP _F and OA _F are between ΔP _n and ΔP _n+1 and QA _o and QA _o+1 , respectively, first, from the difference x between QA _F and QA _o , for example, θ is calculated by proportional division. Find _n,X and θ _n+1,X , then ΔP _F
θ _F between θ _n,X and θ _n+1,X can be determined from the difference y between and ΔP _n . That is, θ _n,X = θ _n,o + (θ _n,o+1 −θ _n,o )x/ΔQA θ _n+1,X = θ _n+1,o + (θ _{n+1,o+ 1} −θ _n+1,o )x/ΔQA θ _F =θ _n,X + (θ _n+1,X −θ _n,X )y/ΔΔP where ΔQA=QA _o+1 −QA _o , ΔΔP= ΔP _n+1 −
Calculated by ΔP _n . Therefore, when the driver depresses the accelerator pedal 1, the position is input to the computer 3 by the sensor 2, and the computer 3 determines the appropriate valve plate based on the pressure difference and air flow rate input from the sensor 5 provided in the engine 4. The stepping motor 14 calculates the opening degree θ _F of the valve and compares it with the current opening degree θ _N detected by an opening sensor (not shown) to give the motor drive circuit the necessary number of pulses and direction of rotation. Plate opening θ _F
They are becoming more and more driven to achieve their goals.

The embodiment of the present invention is configured as described above,
Next, the operation will be explained based on the flowchart of FIG. In Fig. 5, if ΔP = 100 mmHg and θ = 15°, then QA = 10 g/s (point a). Since this is uniquely determined, QA=10g/s, ΔP=
To be 100mmHg, θ must be 15°.

When the driver depresses the accelerator pedal 1, the position of the pedal is detected by the sensor 2, and the computer 3 calculates a target air flow rate _QAF that is larger than the current air flow rate _QA1 (step 101). On the other hand, the current valve plate 12 (when stepping in here)
The differential pressure sensor 21 detects that the pressure difference ΔP _N across the valve is ΔP ₁ , and the valve plate 1 at this time
An opening sensor (not shown) detects that the opening degree θ _N of No. 2 is θ ₁ (step 102). Therefore, the target opening degree θ _F of the valve plate required to obtain the target air flow rate QA _F based on the current pressure difference ΔP _N (=ΔP ₁ ) is calculated using ΔP ₁ and QA _F as shown in FIG. The magnitude θ ₂ that coincides with the characteristic curve of θ passing through the intersection b with
is calculated using the θ map shown in FIG. 6 (step 103). Then, it is determined whether the value of θ _F is the same as the detected value θ _N described above (step 104), and if not, the opening degree θ _N (θ ₁ ) is adjusted to match θ _F (θ ₂ ). The stepping motor 14 is rotated (step 105).

However, when the valve plate opening degree θ _N is opened from θ ₁ to θ ₂ , the flow path resistance of the valve decreases, so the pressure difference ΔP _N becomes smaller and becomes ΔP ₃ {Position C (ΔP ₃ in FIG. 5) , QA ₃ , θ ₂ )}, therefore, the air flow rate QA _N actually flowing through the throttle valve 12 is smaller than QA _F.

Therefore, the process returns to step 102 and a new current pressure difference ΔP _N (ΔP ₃ ) and opening degree θ _N (=θ ₂ ) are detected.
Also, recalculate the target opening θ _F (step
103), the stepping motor 14 is controlled so that θ _N matches θ _F (step 105), and the point d in Figure 5 (ΔP ₃ , QA _F , θ ₄ ) is reached, but in the same way as in the above case. Since the pressure difference ΔP _N becomes small, the point e (ΔP ₅ ,
QA ₅ , θ ₄ ), and the above operation is repeated to finally reach the target z point (ΔP _F , QA _F , θ _F ). At this point, the opening degree θ _N = θ _F (step
104), the target air flow rate QA _F is obtained.

Since this calculation is performed using the computer 3, the time from the measurement of ΔP _N to the output of the value of θ _N and the adjustment of θ by the air control actuator 6 is extremely short, so the adjustment action is from point a to point b. Point → c
The process is not performed from point to point d, etc., but from point a to point b to point z, as shown by the solid line in FIG.

Figure 9 shows the air flow rate characteristics when the horizontal axis is the opening degree θ and the vertical axis is the pressure difference ΔP on a logarithmic scale, and the air flow rate QA is used as a parameter. A QA map (see FIG. 10) in which the QA values corresponding to each combination of ΔP and θ values are digitally recorded is stored.

The operation in this case will be explained based on the flowchart shown in _FIG .
201), but at the same time, the current pressure difference ΔP _N and opening degree θ _N (position α in Figure 9) are detected (step 202), and the current pressure difference ΔP N and opening degree θ N are detected based on the QA map in Figure 10 using ΔP _N and θ _N. The air flow rate QA _N is calculated (step 203), and it is determined whether QA _N matches QA _F (step 204). and if not the same
The amount of movement of the opening θ is determined based on the magnitude relationship between QA _N and QA _F. For example, θ _F = θ _N + K ₁ (QA _F − QA _N ) where K ₁ is a constant. Therefore, determine the target opening degree θ _F (step
205), the stepping motor 14 is rotated so that θ _N matches θ _F (step 206), and the stepping motor 14 attempts to move from position α to position β in FIG. 9, but as described above, the opening angle θ _N When increases, the throttle valve 12
reaches position γ due to the decrease in flow path resistance. Then, as in the case described above, the process returns to step 202, where new ΔP _N , θ _N and QA _N are detected and calculated, and if QA _N is not the same as QA _F , a new θ _F smaller than the previous one is calculated. and the motor 14 is controlled. By repeating such operations, QA _N =QA _F is finally achieved at position ω (ΔP _F , Q _F , QA _F ) (step 204). In this case as well, actual operation control is performed as shown by the solid line in FIG. Also QA
Interpolation calculations can be performed on the map as well in the same way as the θ map described above.

Figure 12 shows the air flow rate characteristics when the horizontal axis is the air flow rate QA, the vertical axis is the opening degree θ on a logarithmic scale, and the pressure difference ΔP is used as a parameter. A ΔP map (see FIG. 13) in which the ΔP value corresponding to each combination of QA and θ values is digitally recorded is stored.

The operation in this case will be explained based on _the flowchart shown in _FIG . Pressure difference ΔP _N at position f) in Figure 12,
The opening degree θ _N is detected (step 302), and the target pressure difference ΔP _F is determined based on the ΔP map in Fig. 13 using θ _N and QA _F.
is calculated (step 303), and it is determined whether ΔP _N matches ΔP _F (step 304). If they are not the same, change QA _N to QA _F while keeping the opening degree θ _N (= θ ₁ ).
In order to do this, ΔP _F must be ΔP ₂ which is larger than the magnitude ΔP ₁ at position f, but if you try to increase the intake air flow rate QA of the engine, the pressure difference ΔP will inevitably become smaller, so the opening θ must be made larger than θ _N . Let the increase in θ be a function of the difference between the target pressure difference ΔP _F and the current pressure difference ΔP _N ,
It is determined based on the difference between ΔP _F and ΔP _N. As a result, the target opening degree θ _F is determined by the equation, for example, θ _F =θ _N +K ₂ (ΔP _F −ΔP _N ), where K ₂ is a constant (step 305). Accordingly, the motor is controlled by maintaining the state of pressure difference ΔP _N (=ΔP ₁ ) (step
306), when the opening degree is increased from θ _N (=θ ₁ ) to θ _F (=θ ₂ ) and moved from position f to position g, the flow path resistance of the valve plate 12 increases as the opening degree increases. As ΔP decreases, it eventually moves to position h, but the air flow rate QA ₂ at this position h is equal to the target
QA will be smaller than _F. Then, as in the case described above, the process returns to step 302 and new ΔP _N , θ _N , ΔP _F
The above operation is repeated by detecting and calculating ΔP _N at the throttle opening θ _F at position Y.
=ΔP _F (step 304), and the target air flow path QA _F
is obtained. In this case as well, since the operating speeds of the computer 3 and the throttle valve 12 are extremely fast, the locus of operation is as shown by the solid line in FIG. 12. It goes without saying that interpolation calculations can be performed on the ΔP map in the same manner as on the above-mentioned maps.

Note that the above air flow rate control using the θ map, QA map, or ΔP map has been described for the case of increasing QA, but it can also operate in the same way when decreasing QA. Even if QA _F is constantly changing, it is always directly or indirectly linked to the current QA and target.
Since we are performing control while comparing with QA _F ,
Get it done effectively.

As described above, according to the present invention, a θ map, a QA map, or a ΔP map is stored in the computer in advance, and when the target value of a parameter is between the values obtained from the map, this value is calculated by interpolation. Since the target value, etc. is determined to obtain the target QA _F, etc., the relatively large delay time and pressure loss that occur when measuring the air flow rate using an air flow sensor can be eliminated, and the throttle valve Since the sensor itself plays the role of an air flow sensor, there is no fluid-dynamic or mechanical delay time in detecting the air flow rate, and the delay time of the differential pressure sensor that detects the pressure difference and the computer processing time can be ignored. Therefore, the air flow rate control can be performed quickly and stably, and in particular, the air flow rate control in a transient state can be performed extremely quickly and accurately.

In addition, the variables related to control are air flow rate, opening degree, and pressure difference, all related to the throttle valve, and since the opening degree and pressure difference are detected to obtain the required air flow rate, changes in the engine over time can be controlled. The change in air flow rate caused by Flow rate can be controlled with high precision. Also, even if there is a change in the differential pressure sensor over time, it is small compared to the change in the engine over time.
Since the change is also gradual, it can be corrected by learning control. Since it is not affected by the condition of the engine, it has the advantage that it can be applied without modification to many types of engines with different displacements and setting characteristics, and it is not affected by changes in engine characteristics over time. The device according to the invention can be adapted to all types of engines, reducing manufacturing costs.

Furthermore, the maps stored in the computer are not difficult to make, and once they are made, the cost becomes lower the more they are mass-produced, and there is no problem in terms of physical reliability.

In the above explanation, a stepping motor is used to adjust the opening degree θ, but if the opening degree θ is detected with a rotary encoder, potentiometer, etc. and the signal is input to a computer, the opening degree can be adjusted. It is also possible to control the air flow rate by means of a servomechanism using a DC or AC motor as the regulating motor. In addition, the control speed can be arbitrarily set according to the computer algorithm and the drive speed of the motor used, and since the computer controls the fuel supply amount and air flow rate, the engine rotation speed and vehicle speed can be changed by changing the program. , control of the air-fuel ratio, etc., and furthermore, various controls such as optimal control of the engine state can be performed only by the configuration according to the present invention.

Thus, according to the present invention, the air supplied to the engine can be controlled with high precision at any speed using a device that is simple in structure, can be manufactured at low cost, and is not affected by engine characteristics, and can also be used to control various types of engine control. There is also a possibility of It goes without saying that the present invention can be applied to either a fuel-priority type fuel supply system or an air-priority type fuel supply system.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a fuel supply system using an air supply amount control method according to the present invention, FIG. 2 is a cross-sectional view showing an example of an air control actuator according to the present invention, and FIG. Figure 4 is a schematic diagram with a reference opening detection mechanism, Figures 5, 9, and 12.
The figure shows air flow characteristics in the device according to the present invention, Figures 6, 10 and 13 are schematic diagrams showing maps stored in the computer, and Figure 7 is interpolated using the map shown in Figure 6. 8, 11, and 14 are flowcharts for air flow rate control using the maps shown in FIGS. 6, 10, and 13, respectively. 1...Accelerator pedal, 2...Sensor, 3...
...Computer, 4...Engine, 5...Sensor, 6...Air control actuator, 7...Fuel control actuator, 11...Throttle valve body, 12...Valve plate, 13...Shaft, 1
4... Stepping motor, 15, 16... Gear, 17... Lever, 18... Switch, 19,
20...Pressure detection port, 21...Differential pressure sensor.

Claims (1)

[Scope of Claims] 1. In a fuel supply system for an internal combustion engine using an air supply amount control method configured such that the air flow rate to be supplied to the internal combustion engine can be controlled by an actuator operated by a computer, It is equipped with a differential pressure sensor that detects the pressure difference (ΔP) between the two, and an opening sensor that detects the throttle valve opening (θ).
The pressure difference (ΔP), the throttle valve opening (θ),
Air flow characteristics related to air flow rate (QA) are digitally stored in the computer's memory, and the air flow characteristics determine the maximum value smaller than each value for the target QA _F and ΔP at that time.
QA _o , ΔP _n and the minimum value QA _o+1 larger than each value,
The target opening degree θ _F is calculated by reading multiple θ values corresponding to the combination with ΔP _n+1 and performing interpolation calculations, and by adjusting the throttle valve opening degree θ to θ _F , the air flow rate can be adjusted. A fuel supply device characterized in that the control is performed. 2. In a fuel supply system for an internal combustion engine using an air supply amount control system configured so that the air flow rate to be supplied to the internal combustion engine can be controlled by an actuator operated by a computer, the pressure difference (ΔP) between the upstream and downstream sides of the throttle valve is ), and an opening sensor that detects the throttle valve opening (θ).
Air flow characteristics related to pressure difference (ΔP), throttle valve opening (θ), and air flow rate (QA) are digitally stored in the computer memory.
Due to the air flow characteristics, a plurality of values corresponding to the combination of maximum values θ _o and ΔP _n smaller than each value and minimum values θ _o+1 and ΔP _n+1 larger than each value for θ and ΔP at that time are determined. QA is read out, the QA at that point is calculated by interpolation calculation, and this QA is the target QA _F.
1. A fuel supply device characterized in that air flow rate is controlled by adjusting a throttle valve opening (θ) so that 3. In a fuel supply system for an internal combustion engine using an air supply amount control system configured such that the air flow rate to be supplied to the internal combustion engine can be controlled by an actuator operated by a computer, the pressure difference (ΔP) between the upstream and downstream sides of the throttle valve is ), and an opening sensor that detects the throttle valve opening (θ).
Air flow characteristics related to pressure difference (ΔP), throttle valve opening (θ), and air flow rate (QA) are digitally stored in the computer memory.
Based on the air flow characteristics, the maximum values QA _o and θ _n that are smaller than the target QA _F and θ at that time are determined.
Read out multiple ΔP corresponding to the combination of minimum value QA _o+1 and θ _n+1 that are larger than each value, calculate ΔP by interpolation calculation, and make sure that this ΔP becomes the target ΔP _F. A fuel supply device characterized in that air flow rate is controlled by adjusting a throttle valve opening (θ).