JPH0526017B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel supply device for increasing the amount of fuel in a supercharged engine during acceleration.

(Prior art) Controlling the amount of fuel supplied according to engine operating conditions has been practiced for a long time, and even in supercharged engines that have a supercharger in the intake passage upstream of the throttle valve, for example, special As disclosed in Japanese Patent Application Laid-open No. 55-98626, a device is known that controls the amount of fuel injected from a fuel injection valve based on the amount of intake air detected by an air flow meter.

By the way, when an engine is accelerating, the flow rate and flow velocity of intake air increase rapidly as the throttle valve is opened. In this case, the problem is that the fuel cannot keep up with the increase in intake flow velocity, resulting in a temporary thinning of the air-fuel mixture and a decrease in output. To solve this problem, a device is known, as disclosed in Japanese Patent Laid-Open No. 56-154132, in which the amount of fuel injection is increased during acceleration according to the depression speed of the accelerator pedal, etc.

However, when such a device is used in a supercharged engine, there remains the problem that the fuel increase value during acceleration does not necessarily match the increase in intake air amount, depending on the operating process until acceleration occurs. It had been. In other words, in a supercharged engine, for example, immediately after deceleration from a high-load operating state, the supercharger is rotating due to inertia, so when acceleration is performed immediately after deceleration, the pressure upstream of the throttle valve is high; Additionally, when accelerating from a state in which the turbocharger is not operating due to continued low-load operation, the pressure upstream of the throttle valve becomes relatively low. The starting pressure upstream of the throttle valve is different. and,
The amount of intake air varies depending on this pressure. Therefore, by simply controlling the fuel injection amount in accordance with the depression speed of the accelerator pedal, it has not been possible to obtain an appropriate increase value in accordance with the intake air amount during acceleration.

(Objective of the Invention) The present invention solves these conventional problems.In a supercharged engine, the intake air after the start of acceleration fluctuates depending on the pressure upstream of the throttle valve at the start of acceleration. It is an object of the present invention to provide a fuel supply device that can increase the amount of fuel commensurately with the anticipated increase in the amount of fuel.

(Structure of the Invention) The present invention is a fuel supply device for a supercharged engine in which a supercharger is interposed in an intake passage upstream of a throttle valve, and includes an acceleration detection means for detecting when the engine is accelerating; It includes a pressure detection means for detecting the pressure between the throttle valve and the supercharger, and a fuel metering device. This fuel metering device receives the outputs of both of the detection means and increases the amount of fuel supplied to the engine during acceleration at a predetermined rate of increase, and increases the rate of increase as the pressure at the start of acceleration increases. It's becoming like that. As a result, the increase value of the fuel increase, which is performed in anticipation of an increase in the intake air amount to compensate for the response delay of fuel supply during acceleration, can be changed to the increase in the intake air amount after the start of acceleration, which depends on the above pressure at the start of acceleration. As you deserve,
The configuration is such that the correction is made appropriately.

(Example) In FIG. 1, 1 is an engine body, 3 is an intake passage that supplies intake air introduced via an air cleaner 4 to the combustion chamber 2 of the engine body 1, and 5 is an exhaust passage. The intake passage 3 is provided with a throttle valve 6 that operates in conjunction with an accelerator pedal (not shown), and a supercharger 7 is provided upstream thereof. In the figure, this supercharger 7 uses a turbo supercharger in which a compressor 9 provided in the intake passage 3 is driven by a turbine 8 provided in the exhaust passage 5. A driven supercharger may also be used. 10 is the above supercharger 7
This is a waste gate valve to control the maximum boost pressure of the engine.

A fuel injection valve 11 is provided in the intake passage 3 downstream of the throttle valve 6, and this fuel injection valve 11 is controlled by a control unit 20.
In order to control the amount of fuel injected from this fuel injection valve 11 according to the operating state, an air flow meter 12 for detecting the amount of intake air is provided upstream of the supercharger 7 in the intake passage 3, and a rotation speed sensor is provided in the engine body 1. 13 are provided, and detection signals from these are input to the control unit 20. Also, a potentiometer 14 that detects the opening degree of the throttle valve 6 is used as a detection element for fuel control during acceleration.
and a pressure sensor (pressure detection means) 15 that detects the intake pressure between the throttle valve 6 and the supercharger 7.
are provided, and detection signals from these are also input to the control unit 20.

The control unit 20 includes means 21 for determining the basic injection amount of fuel according to the operating condition, acceleration detection means 25 for detecting when the engine is accelerating based on the detection signal from the potentiometer 14, and The fuel metering device 30 includes a fuel metering device 30 and a drive circuit 40 for the fuel injection valve 11. The means 21 for determining the basic injection amount detects the engine rotation speed by an engine rotation speed detection circuit 22 that receives a signal from the rotation speed sensor 13, and uses this rotation speed detection signal and intake air from the air flow meter 12. A basic injection amount calculation circuit 23 receiving the amount detection signal calculates a basic fuel injection amount (injection pulse width) according to the intake air amount per engine revolution. The acceleration detection means 25 includes a differentiation circuit 26 that receives a throttle valve opening detection signal from the potentiometer 14, and a comparison circuit 28 that compares its output with a set value 27.
The differentiation circuit 26 determines the rate of change in the throttle valve opening, and when the rate of change exceeds a set value, an acceleration detection signal is output from the comparison circuit 28. In addition, the fuel metering device 3
0 includes an acceleration correction calculation circuit 31 which receives the acceleration detection signal and applies a predetermined fuel increase rate during acceleration;
a hold circuit 3 for correcting the increase rate according to the pressure detected by the pressure sensor 15;
2. Pressure correction calculation circuit 33 and correction circuit 34
and an injection amount calculation circuit 35 that receives the output of the correction circuit 34 and increases the fuel injection amount. The hold circuit 32 receives the acceleration detection signal and the detection signal of the pressure sensor 15 and holds the detected pressure at the start of acceleration, and the pressure correction calculation circuit 33 receives a correction value according to the detected pressure output from the hold circuit 32. is determined, and the correction circuit 34 corrects the fuel increase rate in accordance with the correction value, thereby increasing the fuel increase rate at which the detected pressure increases. The injection amount calculation circuit 35 is connected between the basic injection amount calculation circuit 23 and the drive circuit 40,
When not accelerating, the injection pulse giving the basic injection amount is sent as is to the drive circuit 40, and when accelerating, the output of the correction circuit 34 is received via the gate circuit 36,
By multiplying the basic injection amount by the corrected fuel increase rate, the fuel injection amount is increased, that is, the pulse width of the injection pulse is widened.

According to this device, during normal operation when the rate of change of the throttle valve opening is below a predetermined value, the basic injection amount of fuel calculated by the basic injection amount calculation circuit 23 based on the intake air amount and the engine speed is The fuel is supplied from the fuel injection valve 11. Furthermore, during acceleration when the rate of change of the throttle valve opening is equal to or greater than a predetermined value, the fuel metering device 30 increases the amount of fuel supplied, thereby preventing the air-fuel mixture from becoming lean during acceleration.

In this case, in the fuel metering device 30, the fuel increase rate during acceleration determined by the acceleration correction calculation circuit 31 is adjusted between the throttle valve 6 and the supercharger 7.
The correction circuit 34 corrects the pressure in accordance with the pressure between the two and provides an appropriate fuel increase rate commensurate with the increase in intake air amount during acceleration. In other words, in a supercharged engine, due to the intake inertia of the supercharger 7, the above-mentioned pressure at the start of acceleration changes if the operating progress until acceleration is different, so the throttle valve 6 is closed during acceleration. The amount of intake air sent to the combustion chamber 2 through the engine also changes depending on the pressure. For example, when acceleration is performed immediately after deceleration from a high-load operating state, or when acceleration is performed from a constant-speed operating state. The above intake air amount is larger than that of the above. In contrast,
The fuel increase rate is corrected according to the above pressure, and the higher the above pressure, the larger the fuel increase rate, so that the fuel increase rate corresponds to the change in the intake air amount depending on the above pressure, and the appropriate air-fuel ratio is achieved. It will be given to you.

FIG. 2 shows another embodiment of the invention. In this embodiment, in addition to a pressure sensor 15 that detects the pressure between the throttle valve 6 and the supercharger 7, a pressure sensor 16 that detects the pressure downstream of the throttle valve 6 is used.
has been established. Further, in the fuel metering device 30 of the control unit 20, both the pressure sensors 15,
The differential amplifier circuit 37 receiving the output from the fuel pump 16 calculates the difference between the two pressures, and the fuel increase rate is corrected in accordance with this pressure difference. Other structures are similar to the embodiment shown in FIG. According to this embodiment, the pressure between the throttle valve 6 and the supercharger 7 is determined as a relative pressure to the pressure downstream of the throttle valve 6, and this relative pressure more accurately corresponds to the intake air amount. , the correspondence between the increase in intake air amount during acceleration and the fuel increase rate is improved.

In the above embodiment, the fuel is supplied by the fuel injection valve 11, but the fuel may be supplied by using a carburetor.

(Effects of the Invention) As described above, the present invention increases the amount of fuel supplied to the engine during acceleration in a supercharged engine, and detects the pressure between the throttle valve and the supercharger. The higher the above pressure at the start of acceleration, the larger the fuel increase rate, so the amount of intake air during acceleration varies depending on the inertia of the supercharger and differences in the operating process up to acceleration. Also, the increase in fuel amount, which is performed in anticipation of an increase in the amount of intake air to compensate for the delay in the response of fuel supply during acceleration, is adjusted to account for the increase in the amount of intake air after the start of acceleration, making it possible to obtain an appropriate air-fuel ratio. can. Furthermore, the above-mentioned fuel increase correction can be performed with a relatively simple structure by using the pressure detection means and a fuel metering device that corrects the fuel increase value during acceleration according to the detected pressure. be.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the device of the present invention;
FIG. 2 is a schematic diagram showing another embodiment. 1...Engine body, 3...Intake passage, 6...
Throttle valve, 7...supercharger, 11...fuel injection valve, 15...pressure sensor, 25...acceleration detection means, 30...fuel metering device.

Claims (1)

[Claims] 1. A fuel supply device for a supercharged engine, which includes a supercharger interposed in an intake passage upstream of a throttle valve, and includes an acceleration detection means for detecting when the engine is accelerating, and the throttle valve and the supercharger. a pressure detection means for detecting the pressure between the engine and the engine; and a pressure detection means for increasing the amount of fuel supplied to the engine during acceleration at a predetermined increase rate based on the outputs of both of the above detection means, and increasing the above pressure at the start of acceleration. 1. A fuel supply device for a supercharged engine, comprising: a fuel metering device for increasing the fuel increase rate.