JP2960941B2 - Engine fuel control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for controlling a fuel injection amount in an engine.

[Prior art] Conventionally, an engine in which the fuel injection amount is adjusted by electronic control is provided with an air flow meter or a hot wire type air flow sensor for detecting the intake flow rate, and the fuel injection amount is determined based on the detection signal. Is generally set.

However, since the air flow meter and the hot wire type air flow sensor are relatively large, they have disadvantages in terms of layout, tend to increase intake resistance, and easily cause a response delay. In recent years, for example, as disclosed in Japanese Patent Laid-Open No. 59-15656, an intake pressure sensor (MAP sensor) for detecting the pressure in the intake pipe is provided, and a data map or the like is used based on the pressure detected by the sensor. There has been known a method of setting a fuel injection amount.

[Problems to be solved by the invention]

Generally, when the throttle valve is suddenly closed at the time of deceleration in the engine, the negative pressure on the downstream side of the throttle valve temporarily increases, and the fuel adhering to the inner wall of the intake pipe or the like is carried to the combustion chamber by the pressure. , Overburn may cause afterburning.

As means for avoiding this situation, auxiliary air is automatically supplied into the intake pipe by detecting the negative pressure of the intake pipe during deceleration.
It has been known to provide an AAV (Anti Afterburn Valve) to dilute the air-fuel mixture with the above-described auxiliary air. However, such an auxiliary air supply means controls the fuel injection amount based on the intake pressure as described above. In such a case, the intake air pressure sensor reads the pressure change caused by the supply of the auxiliary air and increases the fuel injection amount, so that the fuel dilution effect of the auxiliary air may be reduced. is there.

In view of such circumstances, the present invention can perform appropriate fuel control based on intake pressure, and can effectively prevent an over-rich phenomenon caused by a change in intake pressure during deceleration. It is intended to provide a device.

[Means for solving the problem]

The present invention provides a fuel control device for an engine, comprising: a pressure detection unit that detects a pressure in an intake passage downstream of a throttle valve; and a control unit that controls a fuel injection amount based on the detected pressure. An auxiliary air supply unit for supplying auxiliary air into an intake passage downstream of the throttle valve is provided. A pressure extraction unit for detection by the pressure detection unit is provided in the intake passage from an air supply unit by the auxiliary air supply unit. Is also provided at a position on the upstream side.

(Operation)

According to the above configuration, the fuel injection amount is controlled based on the pressure in the intake passage downstream of the throttle valve, and the auxiliary air supply unit supplies the auxiliary air at the time of deceleration, thereby preventing the occurrence of over-rich. . In addition, since the pressure extracting section is provided at a position upstream of the air supply section by the auxiliary air supply section, the influence of the supply of the auxiliary air on the detection result of the pressure detection section is extremely small. The fuel injection amount is rarely increased with the supply of air.

〔Example〕

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

In the figure, reference numeral 10 denotes an engine body, cylinders are provided before and after the engine body, and a rotor 12 is provided in each cylinder. The low-load intake port 141 is located at the position facing each cylinder.
A high-load intake port 142 is formed. The low-load intake port 141 is connected to a low-load independent intake passage 161, and the high-load intake port 142 is connected to a high-load independent intake passage 162. Each low-load independent intake passage 161 joins the low-load collective intake passage 181 on the upstream side, and each high-load independent intake passage 162 joins the high-load collective intake passage 182 on the upstream side. Thus, the low-load collective intake passage 181 and the high-load collective intake passage 182 join the collective intake passage 20 on the upstream side.

An air cleaner 22 is provided in the 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 appropriately opened at both low load and high load, and the high load throttle valve 24
The valve 2 is opened only when the load is high, so that the intake is performed only from the low-load intake passages 161 and 181 at a low load, and the intake is also performed from the high-load intake passages 162 and 182 at a high load. It has become.

Each of the independent intake passages 161 and 162 is provided with an injector 26 for directly supplying fuel into the passage 161 and 162. Further, an upstream portion and a downstream portion of the low-load throttle valve 241 are communicated by an ISC (Idle Speed Control) passage 28, and an ISC valve 29 is provided in the ISC passage 28.
These control the engine speed during idling.

Each low load independent intake passage 161 has its pressure (negative pressure)
A pressure outlet 31 for taking out air is provided, and each pressure outlet 31 is connected to a common intake pressure sensor (MPA sensor; pressure detecting means) 32 via a pressure outlet passage 30. The intake pressure sensor 32 detects the pressure in the low-load independent intake passage 161 transmitted through the pressure extraction passage 30,
This is converted into an electric signal, and the detection signal is
The data is input to an ECU (control means) 40.

Further, in this device, each low load independent intake passage 161 is provided.
An air outlet 37 is provided at a position 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. AAV (Anti Afterburn Valve) 36
Is provided.

This AAV36 is composed of a diaphragm, the low-load throttle valve 241 closes during deceleration, and opens when the intake pressure drops sharply, and the air-fuel mixture becomes rich with the sudden decrease in the intake pressure. At this time, the AAV 36 is opened and the auxiliary air is supplied to the low-load independent intake passage 161 to prevent afterburn (afterburning) due to over-rich.

In addition to the intake pressure sensor 32, detection signals from a throttle sensor 38, an engine speed sensor, a water temperature sensor, an atmospheric pressure sensor, an intake temperature sensor, and the like (not shown) are input to the ECU 40. The ECU 40 is configured to control the actual fuel injection amount based on the intake pressure detected by the intake pressure sensor 32 and the engine speed.

 Next, the operation of this device will be described.

During operation of the engine, the intake pressure changes due to the opening and closing of each of the throttle valves 241, 242, and the change is detected by the intake pressure sensor 32, and the detection result is input to the ECU 40. The ECU 40 controls an appropriate amount of fuel injection based on the detected intake pressure and engine speed.

During such an operation, when the throttle valve is suddenly fully closed at the time of deceleration and the intake pressure is rapidly decreased, fuel attached to the inner wall of the intake pipe and the like is conveyed into the fuel chamber. The AAV36 opens when the pressure drops,
The auxiliary air is automatically supplied from the air outlet 37 into each of the low-load independent intake passages 161 to dilute the air-fuel mixture, thereby preventing the over-rich phenomenon.

Here, if the auxiliary air supplied through the AAV 36 affects the pressure detection of the intake pressure sensor 32, the fuel injection amount is increased by that amount, and the effect of dilution of the air-fuel mixture by the auxiliary air is reduced. In the device, as shown in the figure, a pressure outlet 31 for detecting the intake pressure sensor 32 is provided at a position upstream of the outlet 37 for the auxiliary air, so that the auxiliary air is The influence on the detection result of the intake pressure is minimized, and the dilution effect by AAV36 is maintained.

Further, as shown in this embodiment, if the air outlet through the ISC passage 28 is provided on the upstream side of the pressure outlet 31, the change in the intake pressure due to the opening and closing of the ISC valve 29 can be measured by the intake pressure sensor 32. Can be read accurately.

Further, in this embodiment, the pressure extraction unit for detecting the intake pipe pressure is provided with a low-load independent intake passage 161 having a relatively small intake volume and a small pulsation amplitude even under a high load.
The pulsation amplitude is determined by the intake pressure sensor 32.
Has a very small effect on the detection result, and therefore, there is an effect that the intake pressure can be accurately detected in a wide operating range from low load to high load, thereby always performing appropriate fuel control. .

In the present invention, regardless of the specific structure of the intake device,
The present invention can be widely applied to an engine in which fuel control is performed based on intake pressure. For example, the present invention is not limited to the case where each cylinder has two intake passages for low load and high load as shown in the above embodiment, and each cylinder is provided with a single intake passage. Can obtain the same effect as described above.

〔The invention's effect〕

As described above, according to the present invention, in the device for controlling the fuel injection amount based on the pressure in the intake passage downstream of the throttle valve, the auxiliary air is supplied into the intake passage downstream of the throttle valve during deceleration. By the supply of the auxiliary air, it is possible to prevent the occurrence of a temporary over-rich phenomenon at the time of deceleration, and to provide a pressure extraction section for detection by the pressure detection means in the intake passage by the auxiliary air supply means. Since the auxiliary air is provided at a position on the upstream side of the air supply unit, the auxiliary air has almost no effect on the detection result of the intake air pressure, and there is an effect that the dilution effect of the auxiliary air can be maintained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an intake device for an engine according to an embodiment of the present invention. 10… Engine body, 161 …… Independent intake passage for low load, 2
6 ... Injector, 31 ... Pressure outlet, 32 ... Intake pressure sensor (pressure detecting means), 36 ... AVV (auxiliary air supply means), 37 ... Auxiliary air outlet, 40 ... ECU (control means) ).

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F02D 35/00 366

Claims (1)

(57) [Claims] An engine fuel control apparatus comprising: a pressure detecting means for detecting a pressure in an intake passage downstream of a throttle valve; and a control means for controlling a fuel injection amount based on the detected pressure. An auxiliary air supply unit for supplying auxiliary air into an intake passage downstream of the throttle valve, and a pressure extraction unit for detection by the pressure detection unit is provided in the intake passage by an air supply unit by the auxiliary air supply unit. An engine fuel control device provided at a position upstream of the engine.