JPH0723701B2 - Electronically controlled fuel injection device - Google Patents

Description

The present invention relates to an electronically controlled fuel injection device for an internal combustion engine.

As one of the methods for determining the optimum fuel injection amount according to the state of the internal combustion engine, a method is known in which the intake pipe pressure of the internal combustion engine is measured and the basic injection amount of fuel is obtained using this as one parameter. .

With this method. Since the intake pipe pressure is constantly pulsating due to the pumping action of the internal combustion engine even if the throttle opening is constant, it is necessary to prevent it from being affected by the pulsation.

[Conventional technology]

Therefore, in the conventional electronically controlled fuel injection device, a filter that cuts the pulsating component from the output of the pressure sensor that detects the pressure of the intake pipe is provided, and the intake pipe pressure that appears in the output of the filter is used as it is to inject the fuel. Has been decided.

[Problems to be solved by the invention]

However, according to the conventional method as described above, even if the intake pipe pressure actually changes, for example, as shown by the solid line 60 in FIG. 6, the detected intake pipe pressure is shown by the alternate long and short dash line 61 in FIG. As a result, the responsiveness of the intake pipe pressure detection deteriorates, and the responsiveness of the fuel injection amount calculated at the time of acceleration is also impaired.

The present invention is an improvement over these conventional drawbacks,
The purpose is to improve the responsiveness during transients while eliminating the influence of pulsation during steady times.

[Means for solving problems]

In order to solve the above-mentioned drawbacks, the present invention is, for example, as shown in FIG. 1, a first intake pipe pressure detecting means 1 for detecting the intake pipe pressure with high sensitivity, that is, a high responsiveness, and an intake pipe pressure with low sensitivity. Detected by the second intake pipe pressure detecting means 2 and the first intake pipe pressure detecting means 1, the detection output of the second intake pipe pressure detecting means 2 and the fluctuation component of the intake pipe pressure are averaged. The acceleration / deceleration detecting means 3 for detecting the transient state of acceleration based on the determination level for acceleration / deceleration determination calculated by the determination level calculating means (not shown), and the acceleration / deceleration transition based on the detection result of the acceleration / deceleration detecting means 3 Selection means 4 for selecting the detection output of the first intake pipe pressure detection means 1 and for the detection output of the second intake pipe pressure detection means 2 in the steady state, and the intake pipe pressure selected by the selection means 4. Fuel injection amount based on detection output And a fuel injection amount calculating means 5 for calculating.

[Action]

When the internal combustion engine is in a steady state, the acceleration / deceleration detecting means 3 does not detect acceleration / deceleration, so that the selecting means 4 has a low detection sensitivity and therefore the pulsating component does not affect the second intake pipe pressure detecting means 2. The detection output is selected, and the fuel injection amount is calculated based on this detection output. When the internal combustion engine is accelerated or decelerated into a transient state, it is detected by the acceleration / deceleration detection means 3, and the selection means 4 selects the detection output of the highly sensitive first intake pipe pressure detection means. The calculation means 5 can determine the fuel injection amount with good responsiveness.

〔Example〕

FIG. 2 is a block diagram of an essential part of an embodiment of the present invention, showing a case where the present invention is applied to an engine control device for performing fuel injection, ignition timing, and idle speed control of an internal combustion engine.

In the figure, 20 is an intake pipe, and a pressure sensor 21 is attached thereto. As the pressure sensor 21, various types such as a capacitive sensor and a semiconductor piezoresistive sensor can be adopted. The output of the pressure sensor 21 is input to the A / D converter 24 via the filter 29 and the input interface 23 of the controller 22, where it is converted into a digital amount and input to the microprocessor (MPU) 26. The filter 29 is a filter that removes noise in this embodiment.

In addition to the output of the crank angle sensor 25 and the outputs from various sensors required for fuel injection, ignition timing, and idle speed control, the input interface 23 receives A / D conversion output. What is not needed is input directly to the MPU 26 via the converter 24.

The MPU 26 reads the output of the A / D converter 24 and the output of the input interface 23 at a predetermined cycle, performs various calculations, and applies a fuel injection control signal a, an ignition timing control signal b, and an idle speed to an injector (not shown). The control signal c is output to an external circuit via the output interface 27. The memory 28 stores programs necessary for the MPU26 to perform the specified processing.
It is stored in.

FIG. 3 is a flow chart showing an example of the fuel injection control process performed by the MPU 26, and S1 to S12 show each step.
The operation of this embodiment will be described below with reference to FIGS. 2 and 3.

The MPU 26 is interrupted by an internal timer or the like every 2 msec, for example, and executes the processing shown in FIG. In this process,
First, the output PM obtained by filtering the pressure detected by the pressure sensor 21 with the filter 29 is read from the A / D converter 24 in FIG. 2, and a new average value PMD is calculated from this PM and the average value PMD of the immediately preceding PM. Start from (S1). This average value PMD indicates an intake pipe pressure value that is not affected by pulsation by setting the averaging coefficient (8 in FIG. 3) to a relatively large value. In the present embodiment, this PMD is a low-sensitivity intake pipe pressure value. The pressure detection value is used.

Next, MPU26 calculated the PMD obtained this time from the value obtained by doubling this PM.
By subtracting, the overcompensated intake pipe pressure value PMOS is obtained (S2). In this embodiment, this PMOS is used as a highly sensitive intake pipe pressure detection value.

Next, the MPU 26 calculates the acceleration / deceleration determination level LVLPM through steps S3 to S9. This is because the PM change amount DPM is obtained by subtracting the PM value (PMO) at a certain time before or at a certain crank angle from this PM (S3), and a new value is calculated from this DPM and the average value MDPM of the immediately preceding DPM. The average value of DPM, MDPM, is calculated (S4), and this is multiplied by a constant k ₁ . Since the MDPM corresponds to the average value of the pulsating component, the acceleration / deceleration determination level LVLPM corresponds to the value obtained by multiplying the average value of the immediately preceding pulsating component by k ₁ . It should be noted that steps S6 to S9 are for limiting the upper limit value of the acceleration / deceleration determination level LVLPM calculated above to k ₂ and the lower limit value thereof to k ₃ . Further, the above k _{1 to} k ₃ may be changed according to engine parameters such as engine speed.

When the MPU 26 calculates the acceleration / deceleration determination level LVLPM as described above, this and the absolute value of the difference between the PMD and the PMOS obtained this time [P
MD-PMOS] and the size is discriminated (S10), and LVPLM is [PMD-P
MOS], the PMOS is set as the intake pipe pressure value PMC used to calculate the basic injection amount (S12), and the PMD is set otherwise (S11). The calculation of the basic injection amount using the PMC is executed in another step.

Fig. 4 shows that the internal combustion engine is in steady state 1 → acceleration state → steady state 2
→ Deceleration state → PM, PMD, PMO when transitioning to steady state 3
It is an illustration of an example of a change state of S. As shown in the figure, in steady state 1, the difference between PMD and PMOS is extremely small, and there is almost no change in PM.
Is near the lowest value k ₂ . Therefore, step S10 in FIG.
Then, it is determined to be YES, and the basic injection amount is calculated by the low-sensitivity intake pipe pressure measurement value PMD with little influence of pulsation. When shifting to the acceleration state, the difference between PMOS and PMD increases rapidly, while PM
The LVLPM based on the change of does not become so large. Therefore, in the early stage of acceleration, NO in step S10 of FIG.
Is determined, the basic injection amount is calculated by the highly sensitive intake pipe pressure measurement value PMOS, and the responsiveness during acceleration is improved. Steady state 2
Then, the difference between PMOS and PMD becomes smaller, so the injection amount is calculated again based on PMD, and when the deceleration state is entered, PM
Since the difference between OS and PMD becomes large, the same as in the acceleration state
The injection amount is calculated based on Then, when the steady state 3 is entered, the fuel injection amount is calculated again according to PMD.

In the above embodiment, the intake pipe measured value PMC used for the injection calculation is P
As the decision level LVLPM for switching from MD to PMOS, a value obtained by multiplying the average value of PM by k ₁ is adopted, but a value obtained by multiplying the average value of the difference between PMD and PMOS by a constant k may be used as the decision level. it can. Instead of comparing the difference between the PMD and the PMOS with the determination level for switching, the switching may be performed when the PMD or the PMOS changes above a determination level within a certain time or within a certain crank angle. Similarly, P of PMC
When switching from MOS to PMD, the change amount of PMOS is the judgment level LV.
It can also be a case where the state has been within a certain period of time after being within the LPM. Further, when the filter 29 is a filter having a large time constant for removing even pulsating components, the amount used for the fuel injection calculation as the insensitive intake pipe pressure type measured value may be PM.

In the above embodiment, a highly sensitive intake pipe pressure measurement value and a low sensitivity intake pipe pressure measurement value were obtained by the filter processing by the software of the MPU 26. For example, as shown in FIG. Noise filter 50 to remove noise
And two filters having different filter constants with the pulsation filter 51 for removing the pulsation component are provided, and the intake pipe pressure measurement value with high sensitivity is obtained from the noise filter 50 and the intake pipe pressure measurement value with low sensitivity is obtained from the pulsation filter 51. It can also be configured as follows. Further, two pressure sensors having different sensitivities may be provided.

〔The invention's effect〕

As described above, the present invention is provided with the highly sensitive first intake pipe pressure detection means and the low sensitivity second intake pipe pressure detection means that is not affected by the pulsating component, and the second intake pipe pressure detection means is provided in the steady state. The fuel injection amount is calculated on the basis of the detection output of the intake pipe pressure detecting means, and the fuel injection amount is calculated on the basis of the detection output of the first intake pipe pressure detecting means during the transition of acceleration or deceleration. It is possible to improve the responsiveness during a transition while removing the influence. Further, since the judgment level for acceleration / deceleration judgment is calculated by averaging the fluctuation component of the intake pipe pressure, there is no erroneous judgment due to the ripple component of the intake pipe pressure, which tends to fluctuate due to engine speed, load, etc.
Acceleration / deceleration determination can be accurately performed, and an appropriate intake pipe pressure can be accurately selected according to the state of the engine.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the configuration of the present invention, FIG. 2 is a block diagram of a main part of an embodiment of the present invention, FIG. 3 is a flowchart showing an example of fuel injection control processing performed by the MPU 26, and FIG. 4 is FIG. FIG. 5 is a block diagram of a main part of another embodiment of the present invention, and FIG. 6 is an explanatory diagram of a conventional problem. In the figure, 1 is a first intake pipe pressure detecting means, 2 is a second
Intake pipe pressure detection means, 3 acceleration / deceleration detection means, 4 selection means, 5 fuel injection amount calculation means, 20 intake pipe, 21 pressure sensor, 22 controller, 23 input interface, 24 A /
D converter, 25 is a crank angle sensor, 26 is an MPU, 27 is an output interface, 28 is a memory, 29 is a filter, 50 is a noise filter, and 51 is a pulsation filter.

Continuation of front page (56) Reference JP-A-57-175217 (JP, A) JP-A-58-28618 (JP, A) JP-A-58-24829 (JP, A) JP-A-57-122136 (JP , A) JP-A-60-156947 (JP, A) JP-A-60-17247 (JP, A)

Claims (1)

[Claims] 1. An electronically controlled fuel injection device for determining a fuel injection amount of an internal combustion engine based on an intake pipe pressure of the internal combustion engine, comprising: first intake pipe pressure detecting means for detecting the intake pipe pressure with high sensitivity. Second intake pipe pressure detecting means for detecting the intake pipe pressure with low sensitivity; determination level calculating means for averaging the fluctuation component of the intake pipe pressure to calculate a determination level for acceleration / deceleration determination; Acceleration / deceleration detection means for detecting a transient state of acceleration / deceleration based on the detection output of the first intake pipe pressure detection means, the detection output of the second intake pipe pressure detection means, and the determination level; and the detection of the acceleration / deceleration detection means. Based on the result, when the acceleration / deceleration is in transition, the detection output of the first intake pipe pressure detecting means is selected,
A selection means for selecting the detection output of the second intake pipe pressure detection means in the steady state, and a fuel injection amount calculation means for calculating the fuel injection amount based on the intake pipe pressure detection output selected by the selection means. An electronically controlled fuel injection device comprising: