JPS6231174B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device for an engine having a supercharger that displays the supercharging state of the engine having an electronically controlled air-fuel ratio control device.

In automobile engines equipped with a supercharger, (1) the supercharging pressure is displayed as a driving indicator for the driver, and (2) the supercharging pressure is displayed as a driving indicator for the driver. It is desirable to display the supercharging status, that is, the supercharging pressure, for the purpose of warning. In particular, warnings regarding abnormal boost pressure (2) are essential for preventing serious accidents.

Conventionally, in order to make such a display, a method has been adopted in which the supercharging pressure is detected by a pressure sensor or a pressure switch, and a display warning is given by a display means such as a meter or a lamp.

FIG. 1 shows a conventional air-fuel ratio control device for an engine having a supercharger. In FIG. 1, 1 is an engine, 2 is an intake pipe, and 3 is an exhaust pipe.

An intake air amount sensor 4 is provided in the intake pipe 2 . The intake air amount sensor 4 detects the intake air amount Q to the engine 1 and outputs it to the arithmetic unit 12.

Further, a fuel injection valve 5, a throttle valve 6, and a pressure sensor 7 (pressure switch) are provided near the engine 1.

A gear 8 having a convex portion at a position corresponding to the top dead center of the engine 1 and interlocked with engine rotation is provided, and a proximity switch 9 is moved by the convex portion of the gear 8. The proximity switch 9, the fuel injection valve 5, and the pressure sensor 7 are connected to an arithmetic unit 12.

Furthermore, the engine 1 is also provided with a temperature sensor 10, and this temperature sensor 10 is also connected to the arithmetic unit 12. Further, a display means 11 such as a meter or lamp is connected to the pressure sensor 7.

Note that 13 is a supercharging blower which is connected to an exhaust turbine 14 via a shaft 15.

Next, to explain the operation of the device shown in FIG. supplying.

Since the intake air amount sensor 4 is a known device, a detailed explanation will be omitted. The calculation device 12 calculates the amount of intake air based on the output of the intake air amount sensor 4, and calculates the amount of fuel that constitutes a predetermined air-fuel ratio.

Furthermore, the computing device 12 forms a pulse signal,
The amount of fuel per pulse is calculated and a time width commensurate with this is given to the pulse signal. This pulse signal is output after being amplified by an amplification means within the arithmetic unit 12, and pulse-drives the fuel injection valve 5. As a result, the fuel injection valve 5 is controlled to open and close so as to inject a predetermined amount of fuel.

The arithmetic unit 12 is further provided with a pulse by a proximity switch 9 and a gear 8 at each top dead center of the engine 1. This pulse for each top dead center is engine 1
Since it depends on the rotational speed of the engine, it is calculated as a setting parameter for the air-fuel ratio according to the rotational speed, and it is made to act on the duration of the driving pulse of the fuel injection valve 5 mentioned above.

Furthermore, the arithmetic unit 12 receives an output from a temperature sensor 10 that detects engine temperature, and is used as a setting parameter for an air-fuel ratio corresponding to the temperature.
The air-fuel ratio control operation described above is a known technique, and a more detailed explanation will be omitted.

Now, the pressure sensor (pressure switch) 7 is connected to a port provided downstream of the throttle valve 6 in the intake pipe 2, and is a known sensor composed of a diaphragm or the like that responds to the pressure inside the intake pipe 2. hand,
Generates an electrical signal according to pressure.

An electrical signal corresponding to this pressure is given to the display means 11, which displays a display according to the intake pipe pressure. This display can be either an analog display depending on the boost pressure or a lamp display depending on the abnormal boost pressure.

In addition, the electrical output of the pressure sensor (pressure switch) 7 is also given to the calculation device 12, which stops the pulse that drives the fuel injection valve 5 when the intake pipe pressure (supercharging pressure) increases abnormally. , engine 1 stops. This fuel supply stop function is an extremely important function in an air-fuel ratio control device for the engine 1 having a supercharger.

That is, the exhaust turbine 14 is strongly energized when the engine output is large, and therefore the supercharging blower 13 linked thereto is strongly energized to strengthen the supercharging and further increase the engine output. Since a positive feedback system is configured, if the boost pressure rises abnormally, there is a fear that if left unchecked, the output will increase to the point of damage to the engine.

Therefore, it is an effective and reliable safety measure to stop the fuel supply in order to stop the engine when abnormal boost pressure is detected, as described above.

However, the above-mentioned safety measures are rarely required, and it cannot be said that simply displaying the supercharging state on the display means 11 is directly related to engine operation, and the performance of the pressure sensor (pressure switch) 7 is The price cannot be said to be very high.

Furthermore, because EGR gas (not shown) is injected into the intake pipe 2 and exhaust gas is blown back from the engine into the intake pipe 2, deposits may adhere to the operating part of the pressure sensor (pressure switch) 7. There is a high risk of interfering with the operation. This malfunction is fatal when the purpose is to protect against abnormal boost pressure that is rarely required.

This invention was made in view of the above circumstances, and eliminates the pressure sensor (pressure switch) with low performance and low reliability. To provide an air-fuel ratio control device for an engine having a supercharger, which is capable of displaying supercharging pressure with high reliability by using a supercharger (referred to as N), and which is economically advantageous without expanding the scale of the device. The purpose is to

Embodiments of an air-fuel ratio control device for an engine having a supercharger according to the present invention will be described below with reference to the drawings. FIG. 2 shows one embodiment of the present invention, and parts unnecessary for explanation of the invention are omitted. In FIG. 2, reference numeral 120 denotes an arithmetic unit, which is composed of an air-fuel ratio control section 121 and a pressure detection section 122.

The air-fuel ratio control section 121 has a function equivalent to that of the arithmetic unit 12 shown in FIG. 1, and the explanation of its operation will be omitted since it would be redundant. Further, the pressure detection section 122 receives the output of the intake air amount sensor 4 and the output of the proximity switch 9 according to the rotation speed. The pressure detection section 122 has a configuration as shown in FIGS. 3 and 4.

In FIG. 3, reference numeral 123 is a calculation section which calculates Q/N using an electric signal corresponding to the intake air amount Q and an electric signal corresponding to the rotational speed N, and outputs the result. The intake air amount Q of the engine is determined by the intake pipe pressure P, the engine speed N, and the volumetric efficiency η.
It is expressed as ∝PNη.

Therefore, since the relationship is Q/N∝P.η, the value of Q/N is considered to indicate the intake pipe pressure P. If strictness is not required here, it is safe to assume that the volumetric efficiency is constant within the normal operating range of the engine, but if considered strictly, it changes depending on the engine condition, that is, the intake air amount Q and the rotation speed N. .

Therefore, the dividing unit 123 corrects the value of Q/N according to the intake air amount Q and the rotational speed N to obtain a pressure detection signal. Then, when this signal is amplified by the amplifying section 124 and displayed on the display meter 110, the display meter 1
The pointer number 10 indicates accurate intake pipe pressure.

Next, in FIG. 4, 123 is the same as the divider 13 in FIG. There is. The output of the comparison amplification section 125 is connected to an indicator lamp.

Now, the operation of the dividing section 123 is as explained with reference to FIG. 3, and generates an electric signal according to the intake pipe pressure. The reference signal 126 is an electric signal corresponding to the limit value of the intake pipe pressure (supercharging pressure), that is, the abnormal supercharging pressure setting value.

Therefore, the comparison widening section 125 compares the abnormal boost pressure set value and the intake pipe pressure (supercharging pressure), and lights up the indicator lamp 111 when the intake pipe pressure increases abnormally. It goes without saying that the reference signal 126 can be set to be equivalent to atmospheric pressure, and in this case the indicator lamp 111 will indicate the start of engine supercharging.

As described above, in the air-fuel ratio control device for an engine having a supercharger according to the present invention, a pressure sensor (pressure switch) with low reliability for detecting intake pipe pressure is not used to control the air-fuel ratio of the engine. Q/N is calculated using only the intake air amount sensor and revolution speed sensor that are provided, and this Q/N is corrected by the respective values of Q and N to detect the intake pipe pressure, which improves accuracy. It has become possible to obtain high detection values and display supercharging pressure with high reliability.

In addition, the division of Q/N and the comparison with the reference pressure can be carried out economically, since the calculation section such as the microprocessor that constitutes the air-fuel ratio control section can be shared, and the scale of the device does not need to be increased too much. The effect is also great.

[Brief explanation of the drawing]

FIG. 1 shows a schematic configuration of a conventional air-fuel ratio control device for an engine having a supercharger. FIG. 2 is a diagram showing the configuration of an embodiment of the air-fuel ratio control device for an engine having a supercharger according to the present invention, and FIGS. 3 and 4 respectively show the air-fuel ratio of an engine having the supercharger shown in FIG. FIG. 3 is a block diagram showing an example of the configuration of a pressure detection section in the control device. 1... Engine, 2... Intake pipe, 3... Exhaust pipe, 4
...Intake air amount sensor, 5...Fuel injection valve, 120...
...Arithmetic unit, 121...Air-fuel ratio control section, 122...
...Pressure detection section, 123...Divide section, 125...Comparison amplification section, 110...Display meter, 111...Display lamp. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An intake air amount sensor that detects the intake air amount of the engine;
It receives the outputs of the rotation speed sensor that detects the engine rotation speed, the intake air amount sensor, and the rotation speed sensor, and generates an electrical signal corresponding to the value obtained by dividing the output of the intake air amount sensor by the output of the rotation speed sensor. The signal is corrected by the output of the intake air amount sensor and the rotation speed sensor to send out a pressure detection signal corresponding to the intake pipe pressure, and the amount of fuel required for the engine is calculated based on the output of the intake air amount sensor and the rotation speed sensor. The present invention is characterized by comprising: a computing device which displays the supercharging state of the engine in response to the output of the computing device; and a fuel injection valve which is driven by the output of the computing device to supply a predetermined amount of fuel to the engine. An air-fuel ratio control device for an engine having a supercharger.