JPS59105967A - Fuel supplying device for engine - Google Patents

Abstract

PURPOSE:To increase a suction pressure without reducing a compression ratio and improve the output of the engine by a method wherein the spray of a fuel injection valve is sprayed against a compression blade directly to cool suction air by utilizing the spray cooling effect of the fuel. CONSTITUTION:The fuel injection valve 42 is arranged in the upstream of a compressor 22 so as to include the blade of the compressor 22 within the injecting angle of the fuel injection valve 42. Accordingly, the fuel, injected from the fuel injection valve 42, collides against the blade of the compressor and vaporizes on the surface of the blade. According to this effect, not only the temperature of the compressor but also the same of suction air may be reduced. The temperature of the suction air is increased by condensation heat since the suction air is compressed by the compressor 22, however, the atomized particles of the fuel is sent into the engine together with the suction air by the compression blade, therefore, the atomized particles absorb the condensation heat as the vaporization heat thereof and the suction air may be cooled efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fuel supply system for an engine, and more particularly to a fuel supply system for an engine that supports a supercharger.

[Prior art]

In an engine with a supercharger, the intake air is compressed by the supercharger in the intake passage, so the temperature of the intake air increases, and the temperature when compressed in the cylinder is higher than that in the cylinder of an engine without a supercharger. Compression temperature becomes much higher than CM. For this reason, supercharged engines have the disadvantage of being susceptible to knocking.

, 141 and FIG. 2, the influence on the engine due to the increase in intake air temperature TS will be explained. Although Figures 1 and 2 were obtained for a specific engine, the basic trends can be considered to be general characteristics that appear in any engine.

FIG. 1 shows the relationship between the intake air temperature T8 and the limit compression ratio at which the knocking phenomenon occurs, using the intake air pressure PS as a parameter. The conditions under which this knock occurs are influenced by ignition timing and air-fuel ratio.

FIG. 1 shows the characteristics when the engine rotational speed is xooo[:r+m:l and the ignition timing and air-fuel ratio are set to the conditions that produce the maximum output of the engine.

In a normal engine without a supercharger, the intake pressure Pa is IC
The characteristics under the conditions of y-g/i) are shown as a. It can be seen from this characteristic a that as the intake air temperature TS increases, the knock limit compression ratio decreases. The compression ratio is 8.5 for normal factory flan.
~9.0, and is designed to be below the knock limit value even when the intake air temperature TS is 8oc.

When a supercharger is installed, the intake pressure PS increases, creating conditions that are likely to cause knocking. Figure 1 shows the characteristics when the intake pressure ps increases to 1.3 (Ky/ad, l).As the intake pressure Ps increases, the air density increases, so the same The compression ratio also refers to the pressure during compression,
If the temperature is high, knocking is more likely to occur. Therefore, the knock limit compression ratio decreases.

For this reason, when a supercharger is added, it is necessary to reduce the compression ratio to prevent knocking.

Figure 2 shows the relationship between intake pressure PS and torque at intake temperature TS.
is shown as a parameter.

As intake pressure PS increases, torque increases. This is compared to the increase in air density and fuel amount, as well as the increase in compression pressure, which improves the thermal sintering efficiency.

However, if the intake pressure Ps further increases, the output will decrease due to knocking. This influence is greater as the intake air temperature T8 is higher.

If the intake air temperature increases in this way, the knock output will decrease and various problems will occur, so it is necessary to lower the compression ratio and the intake air temperature (7fTS) to prevent the occurrence of knock. be. Lowering the compression ratio is undesirable because it lowers the fuel combustion efficiency. On the other hand, in order to lower the intake air temperature TS, an intercooler is used, but an intercooler cannot be installed in a small car with a small engine room space. For this reason, there has been a demand for a device that lowers the intake air temperature with a simple mechanism.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection device that can prevent an increase in the intake air temperature of an overboard engine.

[Summary of the invention]

A feature of the present invention is that the compression vanes of the supercharger are positioned upstream of the supercharger and within the injection angle of the injection valve so that the fuel injected from the fuel injection valve collides with the compression vanes of the supercharger. This is due to the placement of fuel injection valves. When part or all of the fuel spray injected from the fuel injection valve collides with the compression vanes of the supercharger, the compression vanes are cooled by the spray, and an increase in intake air temperature can be prevented.

[Embodiments of the invention]

FIG. 3 shows an embodiment of the present invention. Intake air is led to a compressor section 22 of the supercharger through an air cleaner 12, an air flow meter 14, and a conduit 16.

This air flow rate is controlled by a throttle valve 18, and the flow rate is measured by an air flow meter 14. Compressor section 2
The air compressed in 2 passes through the intake pipe 24 and flows into the engine 2.
6 will be introduced. Exhaust gas discharged from the engine 26 is guided to the turbine 30 via the exhaust pipe 28.
Apply rotational force to o.

The intake air flow rate of the engine is measured by the air flow meter and input into a control circuit 40 consisting of a computer. The control circuit 4o calculates the amount of fuel to be supplied based on the measured value and the rotational speed of the engine, and the fuel is injected into the atmospheric chamber 52 through the fuel injection valve 42 based on this calculation. The atmospheric chamber 52 is provided to maintain the injection portion of the fuel injection valve 42 at atmospheric pressure, and is intended to prevent the injection pressure of the fuel injection valve 42 from being influenced by intake air pressure.

The upper part of the atmospheric chamber 52 opens upstream of the throttle valve 18 as an air population 54, the tip of the throttle valve 18 is located in the lower opening 56, and the opening area of the opening 56 increases when the throttle valve opening is small. can be adjusted. When the throttle valve opening degree is small, a large negative pressure is generated on the downstream side of the throttle valve 18, so the amount of air flowing into the air chamber 52 bypassing the throttle valve 18 increases. By reducing the opening area of the opening 56 at the bottom of the atmospheric chamber 18, the air flow rate is reduced and the idle speed is prevented from increasing.

In addition, even if the opening degree of the throttle valve 18 is large and the throttle valve 18 leaves the opening 56 and exceeds the adjustment range of the opening area of the opening 56, the pressure in the atmospheric chamber 52 is maintained at atmospheric pressure. In order to do this, the opening area of the air population 54 is made approximately four times the opening area of the opening 56.

This reduces the air flow velocity at the air inlet 14 to the opening 56.
The air flow rate is approximately one-fourth of that of the air flow rate, and pressure fluctuations in the atmospheric chamber 52 can be reduced.

There is a communication pipe 58 on the upstream side of the atmospheric chamber 52.
and a bearing 60 of the supercharger.

Thereby, even if the pressure of the shaft bearing 60 becomes atmospheric pressure and the pressure of the compressor 22 of the supercharger becomes negative pressure, it is possible to prevent the oil in the bearing 60 from entering the compressor 22.

The exhaust gas from the engine 26 rotates the turbine 30 of the supercharger through the communication pipe 28 and is discharged through the exhaust pipe 62. The communication pipe 28 is provided with a wastegate valve 64 that bypasses the turbine 30 and allows exhaust gas to flow into the exhaust gas v62. When the turbine rotation speed becomes higher than a predetermined value, or when the pressure generated by the supercharger 22 becomes higher than a predetermined value, the opening degree of the waste gate valve 64 is increased to reduce the amount of exhaust gas guided to the turbine. and maintain the supercharging pressure of the compressor 22 at a predetermined value.

The compressor section 22 is connected to the atmospheric chamber 5 through a check valve 66.
6 through a conduit 68, and when the output pressure of the compressor exceeds atmospheric pressure, it surrounds the check valve 66 and opens the atmospheric chamber 1.
Send air to 8. This allows the pressure in the atmospheric chamber to be maintained at atmospheric pressure. Since the conduit 68 is eccentrically attached to the atmospheric chamber 52, the air that has passed through the conduit 68 is attached to the atmospheric chamber 52.
It flows along the wall of the wall, forming a swirling flow. For this reason, the pressure of the air pumped from the compressor 22 is converted into a speed component in the rotational direction, so the discharge pressure of the compressor is 1
．． If it is about 3 kv/crl, the center of the swirling air flow in the atmospheric chamber 18 will be almost atmospheric pressure, and the injection valve 5 will be at almost atmospheric pressure.
The flow rate characteristics are practically unaffected by pressure fluctuations.

As shown in FIG. 3, the fuel injection valve 42 is connected to the compressor 22
The blades of the compressor are arranged upstream of the fuel injection valve 42 and within the injection angle of the fuel injection valve 42. Therefore, the fuel injected from the fuel injection valve 42 hits the blades of the compressor and vaporizes on the surfaces of the blades. As a result, the temperature of the intake air can be lowered without causing the compressor to swell.

FIG. 4 is an enlarged view of the vicinity of the throttle valve 18 of the embodiment shown in FIG. The tip 72 of the throttle valve is thickened to increase the ability to adjust the opening area of the opening 56 of the atmospheric chamber 52 by adjusting the opening degree of the throttle valve 18. A heat insulating material 76 is interposed between the compressor 22 and the throttle chamber 74.

A chamber 78 is provided on the compressor 22 side of the atmosphere communication pipe 58, and a gap 80 between the chamber 78 and the casing of the compressor 22 is reduced to provide air sealing by a labyrinth effect. A disk 84 is provided in a part of the chamber 78 of the shaft 82 to shake out leaked oil from the bearing 60 side and return it through the return pipe 24 to an oil sump (not shown). The bore diameter of the conduit 16 downstream of the throttle valve and the inlet diameter of the compressor 22 of the supercharger are set to be approximately the same size.

The injection valve 42 has compression vanes 8 of the compressor 22 within the injection angle.
6, the fuel spray from the injection valve 42 directly collides with the compression vane 86, and the intake air is efficiently cooled by the spray cooling effect. Since the compressor 22 compresses the intake air, the temperature of the intake air increases due to the heat of condensation.However, since fuel spray particles are sent together with the intake air by the compression vanes 86, the spray particles convert the heat of condensation into heat of vaporization. It absorbs and efficiently cools intake air.

A cross-sectional spacer can be arranged on the shroud surface of the compression vane 22 of the compressor 22 to promote the cooling effect. This will be explained using FIG. FIG. 5(a) is a cross-sectional view of the compressor 22, and FIG.
). A thermal insulating spacer 92 is located on the shroud surface. In the conventional system, the supply air temperature rises to about 600 to 80C, but in this embodiment, it becomes a low value of about 40C. still.

This actual value is an intake pressure of 1.3 Ky/crti s.
The test was conducted at an engine rotational speed of 3000 (fFl).

FIG. 6 shows the rise characteristics of the turbine rotational speed and intake pressure when the engine rotational speed was suddenly increased from 20001- to fully open the throttle.

Graph a is the characteristic of this embodiment, and graphs b and C are the characteristics of the conventional system.

In the graph of the turbine rotational speed, the reason why the turbine rotational speed when the engine rotates at a constant speed is higher in this embodiment than in other devices is because the compressor 22 is located downstream of the throttle valve 18.
This is because the loss during no-load idling is reduced due to the difference in air density.

In this embodiment, the inlet diameter of the compressor 22 is made equal to the diameter of the conduit 16 downstream of the throttle valve, so there is no resistance or expansion between the conduit 33 and the compressor, and when the throttle valve is suddenly opened, the intake air approaches the speed of sound. flows in smoothly and rotates the compression blades of the compressor 22, so the start-up characteristics of the turbo effect are improved.

FIG. 7 shows another embodiment of the present invention. In this embodiment, the fuel injection valve 42 is provided upstream of the throttle valve 18, and the fuel injection valve 42 and the conduit 16 are provided on the same axis.

It enters the intake pipe and passes through the throttle valve 18 to the compressor 22.
to go into. Fuel is supplied from the injection valve 42.

The supercharger does its work and the supply air source rises when the pressure between the throttle valve 18 is relatively large, so the fuel flows through the throttle valve 18.
Most of it hits the blades 22 of the compressor 22 and is cooled. On the other hand, when the opening degree of the throttle valve 18 is small, the increase in intake air temperature caused by the supercharger hardly becomes a problem. The spray injected from the fuel injection valve 42 collides with the throttle valve 18, where the fuel is atomized into secondary particles, some of which vaporizes before reaching the compression vane, and some of which collides with the compression vane, forming a spray. Perform cooling.

When the engine is started, fuel adheres to the wall surface of the bore of the throttle chamber 74, but since the fuel relatively flows through the wall surface of the lower surface of the chamber puff 4, this does not pose a problem. In order to improve the flow of fuel, the throttle chamber 74 may be inclined so that the downstream side thereof is lowered. Since the atmospheric communication pipe 58 opens on the upper surface of the bore upstream of the throttle valve, there is little fuel flowing into the air communicating pipe 58, and almost no fuel flows into the return pipe 94.

As described above, according to this embodiment as well, it is possible to provide an engine fuel supply system that efficiently lowers the intake air temperature and has excellent anti-knock characteristics.

In the present invention, the spray from the fuel injection valve is applied directly to the compression vane and the intake air is cooled using the fuel spray cooling effect, so the temperature of the intake air can be maintained at 40C regardless of the rise in intake pressure.
Since the intake pressure can be maintained below, the intake pressure can be increased without reducing the compression ratio, and the output can be improved by about 20%. Even in conventional known examples, if an intercooler is provided, the temperature of intake air can be lowered, but the engine room becomes larger. In contrast, in the present invention, there is no need to enlarge the engine room, and space can be effectively used.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between intake air temperature T8 and knock limit compression ratio, FIG. 2 is a diagram showing the relationship between intake pressure P8 and engine shaft torque, and FIG. 3 is a diagram showing an embodiment of the present invention. Fig. 4 is a cross-sectional view of the vicinity of the throttle valve of the embodiment shown in Fig. 3, and Fig.
FIG. 6 is a diagram showing the effect of the embodiment shown in FIG. 5, and FIG. 7 is a diagram showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Filter, 3...Engine, 4...Soft 9wof, 5...Fuel injection valve, 6...Intake pipe, 7...
・Supercharger compressor, 8...supercharger turbine,
18... Atmospheric pressure chamber, 19... Bearing, 22... Compression vane, 26... Opening. 4th Taro (CL) (I7) 60 170 7Q 76,! ,!

Claims (1)

[Scope of Claims] 1. An intake passage that guides air to the engine, supercharging air provided in the intake passage, and a fuel injection valve that supplies fuel according to the state of the engine, wherein the fuel injection A fuel supply device for an engine, characterized in that a valve is disposed upstream of the supercharger and at a position where at least a portion of the compression vanes of the supercharger are within the injection angle of the fuel injection valve.
i. 2. The fuel supply system for an engine according to item 1, wherein the intake passage has an atmospheric chamber at the fuel injection valve mounting position.