JPH03213661A - Fuel control device for engine - Google Patents

Abstract

PURPOSE:To properly execute fuel control at all times by providing a pressure take-off section for detecting intake pressure at a low loading intake passage as described later where pulsation in negative pressure is small in amplitude in an engine equipped with both of the low logging and a high loading intake passage which are mutually independent. CONSTITUTION:When an engine is in operation, intake pressure is changed owing to the opening and/or closing of respective throttle vales 241 and 242 provided for a low and a high collective intake passage 151 and 182 respectively. In this case, change in intake pressure is detected by an intake pressure sensor 32 so that the result of the detection is inputted into an ECU 40. The quantity of fuel injection is then properly controlled based on the detected intake pressure, engine revolution and the like. In a fuel control device as mentioned above, pressure (negative) take-off ports 31 are provided for respective low pressure loading independent intake passages 161 branched out of the low loading collective intake passage 181 in order that its pressure (negative) is taken off, and the respective pressure take-off ports 31 are connected to a common intake pressure sensor 32 via a pressure take-off passage 30.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for controlling the amount of fuel injected into an engine.

[Conventional technology]

Conventionally, engines in which the amount of fuel injection is controlled electronically are equipped with an airflow meter or hot wire type airflow sensor to detect the intake flow rate, and the amount of fuel injection is set based on the detection signal. has become common.

However, since the air 70-meter and the hot wire type air flow sensor are relatively large, they are disadvantageous in terms of layout, tend to increase intake resistance, and tend to have a delayed response. Therefore, in recent years, as shown in Japanese Patent Laid-Open No. 59-15656, for example, an intake pressure sensor (MAP sensor) that detects the pressure inside the intake pipe has been installed, and based on the pressure detected by this sensor, a data map etc. is used to fuel the fuel. Devices that set the injection amount have come to be known.

(Problem to be Solved by the Invention) As often seen in rotary engines, an engine is provided with two independent passages: a low-load intake passage and a high-load intake passage. There is a system in which air is taken in only through the low-load intake passage when a low load is not required, and air is taken through both passages during a high load when a large output is required.

For such engines, fuel injection control can also be performed based on the detection signal of the intake pressure sensor as described above, but especially at high loads, the total intake air volume increases and negative pressure pulsations are caused. Since the amplitude becomes large, erroneous detection by the intake pressure sensor is likely to occur due to the influence of this pulsation, and countermeasures are required.

In response to these circumstances, the present invention detects intake pressure with high accuracy over a wide range of operating conditions, regardless of whether the load is low or high, and controls the appropriate amount of fuel injection based on this. The purpose is to provide a fuel control device that can

[Means to solve the problem]

The present invention is a fuel control device that is installed in an engine that has a low-load intake passage and a high-load intake passage that are independent of each other, and that controls the amount of fuel injection. A control means for controlling the fuel injection amount based on the detected pressure is provided, and a pressure take-out portion for detection by the pressure detection means is provided in the low-load intake passage.

[For production]

According to the above configuration, the actual fuel injection amount is controlled based on the intake pressure detected by the pressure detection means. Moreover, since the pressure extraction section for detection by the pressure detection means is provided in the low-load intake passage where the pulsation amplitude is always small, the influence of the pulsation on the detection results of the pressure detection means is extremely small. few.

〔Example〕

FIG. 1 shows the overall configuration of an engine in a first embodiment of the present invention. Although a rotary engine is shown here as an example, the present invention is not limited to this.
It can also be applied to other engines such as reciprocating engines.

In FIG. 1, 10 is an engine main body, cylinders are provided before and after the engine main body, and each cylinder is provided with a rotor 12. A low-load intake boat 1 is located at a position facing into each cylinder.
41 and a high-load intake boat 142 are formed, and the low-load intake boat 141 has an independent low-load intake passage 161.
However, an independent load intake passage 162 is connected to the high load intake boat 142. Independent intake passage for each low load 1
61 joins the low-load collective intake passage 181 on its upstream side, and each high-load independent intake passage 162 joins the high-load collective intake passage 182 on its upstream side, and The passage 181 and the high load collective intake passage 182 are
It joins the collective intake passage 20 on its upstream side.

An air cleaner 22 is provided in this collective intake passage 20. A low-load throttle valve 241 is provided in the low-load collective intake passage 181 on the downstream side, and a high-load throttle valve 242 is provided in the high-load collective intake passage 182. The low load throttle valve 241 is opened as appropriate during both low load and high load, and the high load throttle valve 242 is opened only during high load. Load intake passage 1
Air is taken in only from 61.181, and when the load is high, air is also taken in from the high load intake passage 162.182.

Each independent intake passage 161, 162 has these passages 16
An injector 26 is arranged which supplies fuel directly into the 1.162. In addition, the upstream and downstream parts of the low-load throttle valve 241 are ISO (Idle 5p).
eed Control) passage 28, and an ISO valve 29 is provided in this ISO passage 28.
These control the engine speed at idle.

Furthermore, as a feature of this device, each low-load independent intake passage 161 is provided with a pressure outlet 31 for taking out the pressure (negative pressure), and each pressure outlet 31 is connected to the pressure outlet 31 through the pressure outlet passage 30. It is connected to a common intake pressure sensor (MAR sensor; pressure detection means) 32. This intake pressure sensor 32 detects the pressure within the low-load independent intake passage 161 transmitted through the pressure extraction passage 30 and converts it into an electrical signal, and the detection signal is EC
It is designed to be input to LI (control means) 40.

In addition, in this embodiment, each low-load independent intake passage 161
An air outlet 37 is provided downstream of the pressure outlet 31, and an air pump (not shown) is connected to each air outlet 37 via an air supply passage 34. is A AV (Ant
i Afterburn Valve) 36 is provided.

This AAV36 consists of a diaphragm, and opens when the low-load throttle valve 241 closes during deceleration and the intake pressure suddenly drops, and the air-fuel mixture becomes rich as the intake pressure suddenly drops. Sometimes, the above AAV36
opens and air is supplied to the low-load independent intake passage 161, thereby preventing afterburn (
Afterburning) is prevented.

In addition to the intake pressure sensor 32, the ECU 40 receives detection signals from a throttle sensor 38, an engine speed sensor (not shown), a water temperature sensor, an atmospheric pressure sensor, an intake temperature sensor, and the like. And this ECU40
The actual fuel injection amount is controlled by this.

The contents of this control are as shown in the flowchart of FIG.

First, various detection signals such as intake pipe internal pressure PM, throttle opening TVO, and engine speed Ne are read (step S1).

After that, the basic fuel injection amount is basically set based on the fuel map of intake pipe internal pressure PM and engine speed Ne, but in transient states during acceleration and deceleration, the intake pipe internal pressure becomes unstable. Therefore, settings are made based on a fuel map of throttle opening TVO and engine speed Ne.

Specifically, the throttle opening f[TVo(
i) and the previously read throttle opening T V O(i-
1) is determined, and depending on whether this value is greater than or equal to a predetermined set value α, it is determined whether the engine is in a transient state or a steady state (step 82 ).

First, if the absolute value of the difference is less than the set value α (No in step S2), it is determined that the steady state is present.

At this time, if it is not the moment when the transition from the transient state to the steady state occurs (No in step S3), the basic pulse width T E 1 (PH) based on the fuel map of the intake pipe pressure PM and the engine speed Ne is changed as usual. served (step S4
), this basic pulse width T E 1 (PM) is directly set as the pulse width TEI used in calculations later (
Step Ss).

On the other hand, if it is the moment of transition from a transient state to a steady state (YES in step S3), the basic pulse width TE1 (PH) is calculated based on the same fuel map as above (step Ss). In addition, throttle opening TV
The basic pulse width T E 1 (DVO) is calculated based on the fuel map of O and the engine speed Ne (step S7
), the ratio of this basic pulse width TE1 (TVO) to the basic pulse width T E 1 (PI3) is calculated as a correction coefficient (step Ss).

This correction coefficient includes the throttle opening TVO and
This is used to prevent the difference between the fuel injection amount and the fuel injection amount that should originally be obtained from the intake pipe internal angular pressure from widening over time when fuel control is performed based on a map between This value is stored in the RAM of the ECU 40 (step S9). However, in this case as well, the basic pulse width TE1 (PM) determined from the negative pressure in the intake pipe is set as the basic pulse width TE1 used in the calculation.

On the other hand, if the absolute value of the throttle opening difference is greater than or equal to the set value α in step S2 (Y in step S2),
ES), the intake pipe internal pressure PM is determined to be in an unstable transient state, and the basic pulse width T E 1 (TVO ) is calculated (step St+), and this basic pulse width T
E 1 (TVO) multiplied by the correction coefficient K calculated in step S8 above is set as the pulse width TE1 (step 511).

Next, for the pulse width TE1 obtained in each step above,
A value TE2 is calculated by multiplying the correction coefficient CAIR based on the intake air temperature and the correction coefficient CBAR based on the atmospheric pressure (step 512). Furthermore, the value obtained by adding the sum CTOTAL of other various correction coefficients to this value TE2 is the actual pulse width T.
P (step 513), and this pulse width T
By outputting a control signal having P to the actuator of each injector 26, an appropriate amount of fuel is injected (step 514).

As described above, in this device, fuel injection control is performed based on the intake pipe internal pressure and the engine rotational speed without using an air flow meter or the like. Moreover, since the pressure take-out section for detecting the pressure inside the intake pipe is provided in the low-load independent intake passage 161 where the intake air amount is relatively small and the pulsation amplitude is small even under high load, the pulsation amplitude is The effect on the detection results of the atmospheric pressure sensor 32 is extremely small.

Therefore, the intake pressure can be accurately detected in a wide range of operating ranges from low load to high load, thereby making it possible to always perform appropriate fuel control.

Furthermore, in this device, as shown in FIG. 1, the air led out from each low-load independent intake passage 161 is collected and guided to a common intake pressure sensor 32, so that the intake pressure is determined by each cylinder. Even if there is variation in the pressure, the inconvenience caused by the variation can be resolved by detecting the average pressure.

Furthermore, in this device, if the air supplied through the AAV 36 affects the pressure detection of the intake pressure sensor 32, the fuel injection amount will be increased by that amount, which may weaken the effect of diluting the air-fuel mixture by the AAV 36. As shown in FIG. 1, by providing the air outlet 37 supplied through the AAV 36 downstream of the pressure outlet 31 for detection of the intake pressure sensor 32, the supplied air can It is possible to minimize the influence on the detection results and maintain the effects of AAV36.

On the other hand, as shown in the figure, by providing the air outlet through the ISO passage 28 upstream of the pressure outlet 31, changes in the intake pressure caused by opening and closing of the ISC valve 29 are detected by the intake pressure sensor 32. Can be read accurately.

In this embodiment, the pressure outlet 31 is provided in each low-load independent intake passage 161, but for example, in the low-load collective intake passage 181, the low-load throttle valve 241
It may also be provided immediately downstream of. However, in this case, the intake pressure becomes slightly unstable due to the turbulence generated at the lower ms passage branch, but if the pressure outlet 31 is provided in the independent intake passage 161 for low load, it becomes stable. This has the effect of being able to detect the intake pressure in the rectified part.

Next, a second embodiment will be described based on FIG.

Here too, each cylinder of the engine body 10 has low-load intake ventilation! 421 and a high-load intake passage 422 are provided, and each passage 421 and 422 is provided with a low-load throttle valve 241 and a high-load throttle valve 242. A communication port 44 that communicates both passages 421 and 422 is provided on the side, and the communication port 4 is provided in the high-load intake passage 422.
An auxiliary throttle valve 243 is provided on the downstream side of 4 (dual throttle structure). Then, when transitioning from a low load state to a high load state, the high load throttle valve 242 opens quickly, whereas the auxiliary throttle valve 243 gradually opens. Air passing through the throttle valve 242 is actively introduced into the low-load intake passage 421 from the communication port 44, thereby preventing a sudden drop in air flow velocity when the high-load throttle valve 242 opens. There is.

Even in such a structure, the low-load intake passage 421,
Specifically, by providing a pressure outlet 31 on the downstream side of the communication port 44 and introducing air into the intake pressure sensor 32 from this pressure outlet 31, accurate intake pressure can be detected without being affected by negative pressure pulsations. It can be carried out.

As described above, the present invention can be applied to engines having both a low-load intake passage and a high-load intake passage, regardless of the specific structure of the intake device.

〔Effect of the invention〕

As described above, the present invention provides an engine having a low-load intake passage and a high-load intake passage that are independent of each other.
The fuel injection amount is controlled based on the intake pressure, and the pressure extraction section for detecting the pressure is provided in the low-load intake passage where the width of negative pressure pulsation is small at all times. It is possible to control fuel injection without using a meter, etc., and it is also possible to suppress the influence of the above-mentioned pulsation on the intake pressure detection results. By accurately detecting pressure, there is an effect that proper fuel control can always be performed.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an engine intake system according to a first embodiment of the present invention, FIG. 2 is a flowchart showing a fuel control operation performed in the engine, and FIG.
FIG. 2 is a configuration diagram of an engine intake device in an embodiment. DESCRIPTION OF SYMBOLS 10... Engine body, 161... Independent intake passage for low load, 162... Independent intake passage for high load, 181.
...Common intake passage for low load, 182...Common intake passage for high load, 26...Injector, 31...Pressure outlet, 32...Intake pressure sensor (pressure detection means), 4
0...ECU (control means).

Claims (1)

[Claims] 1. A fuel control device that is installed in an engine having a low-load intake passage and a high-load intake passage that are independent of each other and controls the fuel injection amount thereof, and includes a pressure detection means for detecting intake pressure, and a pressure detection means for detecting the intake pressure. 1. A fuel control device for an engine, comprising: a control means for controlling a fuel injection amount based on the pressure detected by the engine, and a pressure take-out portion for detection by the pressure detection means is provided in a low-load intake passage.