JPH02115567A - Fuel injection device for engine - Google Patents

Abstract

PURPOSE:To prevent the mixture density from becoming rich and the generation of misfire by providing a quantity adjusting valve for switching a fuel injection valve electromagnetically and an outer open valve for feeding the quantity adjusted fuel into a combustion chamber as well as a pressure reducing means for reducing the pressure in the fuel sump chamber. CONSTITUTION:A quantity adjusting valve 33 for opening/closing a fuel passage 31 is formed at the lower end of a weighing spindle 32. The lower end of a fuel sump chamber is communicated with an outer open valve 37 provided at the lower end of a fuel injection valve 4, so that the quantity adjusted fuel is injected into a combustion chamber. A pressure reducing means for reducing the pressure in the fuel sump chamber 36 formed between the quantity adjusting valve 33 and the outer open valve 37 is further provided. The mixture density is thus prevented from becoming rich due to the fuel leakage as well as misfire is prevented from generating.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention prevents fuel from leaking into the combustion chamber from a fuel injection valve that injects fuel directly into the combustion chamber of the engine when the engine is stopped after warming up. , relates to a fuel injection device for an engine.

(Prior technology) Conventionally, fuel is injected directly into the vicinity of the spark plug in the engine combustion chamber to stratify a mixture with an appropriate concentration, thereby improving ignition performance and making the overall air-fuel ratio leaner, thereby reducing fuel efficiency. For example, Japanese Patent Application Laid-Open No. 63-147
This method is known as described in Japanese Patent No. 924. In this case, a fuel injection valve with an injection port facing the combustion chamber is attached to a member that constitutes the combustion chamber (the side housing in the conventional example above), and is cooled by frequent passage of fuel and air during use. However, when the engine is stopped after warming up, the fuel injection valve is heated by the heat of the engine, and the temperature of the fuel remaining in the fuel injection valve rises, expands in volume, and increases the pressure, which eventually leads to injection. An outward opening valve whose opening is closed by the pressure of a spring may be opened against the pressure of the spring, causing fuel to leak into the combustion chamber.

If fuel leaks in this way, the ratio of air to fuel may become fuel lint at the time of restart, or the spark plug may become wet, causing ignition failure.

(Object of the Invention) The present invention solves the above-mentioned conventional problems by providing means for reducing the pressure in the fuel reservoir chamber of the fuel injection valve, thereby preventing fuel leakage from the fuel injection valve into the combustion chamber. The object of the present invention is to provide a fuel injection device for an engine that prevents the above.

(Structure of the Invention) To achieve the above object, the present invention includes a metering valve that electromagnetically opens a fuel injection valve whose injection port faces the combustion chamber of an engine, and a metering valve that combusts the metered fuel. Assuming that the configuration is equipped with an outward-opening valve that supplies indoor air, the fuel in the fuel reservoir chamber formed between the metering valve and the outward-opening valve is heated by engine heat when the engine is stopped after warming up. This fuel injection device for an engine is provided with a pressure reducing means for reducing the pressure of the fuel reservoir chamber to prevent the fuel reservoir chamber from increasing in pressure due to volumetric expansion.

According to the above configuration, when the engine is stopped after warming up and the pressure in the fuel reservoir chamber inside the fuel injection valve facing the combustion chamber of the engine increases, the pressure reducing means operates to lower the pressure, so the pressure increases. This prevents the outward valve from opening and the fuel in the fuel reservoir chamber leaking into the combustion chamber, eliminating adverse effects such as enrichment of the mixture concentration due to fuel leakage and ignition failure due to dampness of the ignition plug. .

(Example) Hereinafter, an example in which the present invention is applied to a rotary piston engine will be described in detail based on the drawings.

[First Embodiment] Fig. 1 shows a rotary piston engine equipped with a first fuel injection valve that injects fuel directly into the leading side of the combustion chamber and a second fuel injection valve that injects fuel into the intake passage. Figure 2 is a longitudinal cross-sectional view showing the details of the first fuel injection valve, and (1) is a rotor housing with a working chamber ( la
), and a substantially triangular rotor (
2) is supported by an eccentric shaft (3) and rotates eccentrically,
The first fuel injection valve (4), which injects fuel directly to the leading side during compression when the rotor (2) of the working chamber (LA) is in the illustrated state, has its injection port facing the combustion chamber and is connected to the side housing (not shown). and a second fuel injection valve (6) that injects fuel into a position close to the intake boat (24) of the intake passage (5) connected to the intake port (24) opening into the working chamber (1a). ) is provided. A throttle valve (7) and an air flow meter (8) are arranged in this order in the intake passage (5) upstream of the second fuel injection valve (6).

(9) is a fuel pump, which sucks fuel from the fuel tank 00) through the fuel suction passage (11), and this fuel pump (9)
The fuel is supplied to the first fuel injection valve through the fuel supply passage 02) connecting the first fuel injection valve (4) and the second fuel injection valve (6).
It supplies the fuel injection valve (4) and the second fuel injection valve (6). A pressure regulating valve 03) is provided in this fuel supply path θ, and regulates the pressure in the fuel supply path θ to a pressure suitable for fuel injection, and drains excess fuel from the fuel via the drain path. The tank should be returned to 0ω.

05) is a pressure reducing valve, which is interposed in the middle of the pressure reducing passage 06 provided between the fuel supply passage 02) and the drain passage side, and the pressure reducing valve θω and the pressure reducing passage Oω form a pressure reducing means. When the engine is stopped after warming up, which will be described in detail later, the first fuel injection valve (4)
The fuel staying inside the combustion chamber is heated, its temperature rises, and its volume expands, causing phenomena such as fuel leaking into the combustion chamber, leading to fuel richness, or dampening the spark plug, leading to a misfire. This is to prevent q is an air pump, which passes from the intake passage (5) downstream of the air flow meter (8) to the assist air supply passage 08), and is connected to the assist air control '+111 valve 09 provided interposed in this assist air supply passage 08). ) to send assist air to the first fuel injection valve (4), supply air to the combustion chamber before and after fuel injection, pulverize the fuel, and clean the combustion chamber and remove residual burnt gas. The purpose of this is to eliminate the following.

Q (D is a throttle sensor that detects the opening degree of the throttle valve (7) corresponding to the engine load, (21) is an engine speed sensor that determines the operating state from the engine speed, (22) 23) is an engine water temperature sensor that knows the heating state of the engine, and 23) is a control unit that receives the information from the throttle sensor 12 [D], the engine speed sensor (21), and the engine water temperature sensor (22). In response, the first fuel injection valve (4) and the second
Controls the timing and amount of fuel injection from the fuel injection valve (6), and also controls the assist air control valve 09) to control the timing and amount of assist air supplied to the first fuel injection valve (4). It is something. (25) shows the exhaust boat, (26) and (27) show the spark plugs.

Next, the configuration of the first fuel injection valve (4) will be explained based on FIG. 2.

The fuel inlet (30) at the upper end is connected to the fuel supply passage 02), and the fuel passage (30) is connected in the axial direction following this fuel inlet (30).
A metering spindle (32) is installed in this fuel passage (31) with a cylindrical magnetic body (32a) engaged with the upper end thereof, and a metering spindle (32) is installed at the lower end of this metering spindle (32). The first valve forms a metering valve (33) that opens and closes the fuel passage (31) and pressurizes the upper end of the magnetic body (32a).
A spring (34) always urges the metering spindle (32) downward to close the metering valve (33), and a Qlt coil (35) is installed above the metering spindle (32). By turning on this electromagnetic coil (35), the magnetic body (32a) is attracted and the measuring spindle (32) moves to the first position.
Below the metering valve (33), which is pulled up against the spring (34) to open the metering valve (33), there is a fuel reservoir chamber (36).
) is formed, and this fuel reservoir chamber (36) communicates with the fuel passage (31) when the metering valve (33) is opened.

The lower end of this fuel reservoir chamber (36) is connected to the first fuel injection valve (4).
) is connected to an outwardly opening valve (37) provided at the lower end of the second spring (37) with its opening facing the combustion chamber.
8), and from this state the electromagnetic coil (
35), open the metering valve (33), and open the fuel reservoir chamber (33).
36) and the pressure increases, the second spring (
38), the outward opening valve (37) is opened and fuel is injected into the combustion chamber.

(39) is the assist air inlet, which is the assist air control valve θ
A fuel passageway (31), a fuel reservoir chamber (36), and an outward opening valve (37) are connected to the assist air supply path 08) having a
), passing through the assist air passage (40) formed in the direction of the dashed arrow, and passing through the opening provided in the air passage outer wall (41) corresponding to the front of the outward opening valve (37).
42), assist air is blown into the combustion chamber before and after fuel injection, thereby turning the fuel into a combustible mixture at the time of fuel injection.

Figure 3 shows the first fuel injection valve (4) and the second fuel injection valve (6).
The graph shows the usage range of the engine speed on the horizontal axis and the throttle valve corresponding to the engine load on the vertical axis (if we take the force opening, the first fuel injection valve (8)
Only 4) injects fuel along with assist air to the leading side of the compression process, and in this way the spark plug (2)
6) It is possible to stratify a rich air-fuel mixture near (27) to facilitate ignition, while the other parts become a lean air-fuel mixture that is mainly made up of air from the intake passage (5), reducing output too much. It is possible to improve the fuel consumption rate in the low-load, low-speed region (A) such as during unnecessary idling. In addition, in the high-load, high-speed region (B), the second fuel injector (6) is mainly used, and in order to improve ignition performance, the first fuel injector (4) is placed on the leading side of the combustion chamber, and the air pump θ force is stopped. It is used auxiliary with the air cut off to stratify the fuel around the spark plugs (26) and (27) to ensure reliable ignition.

When the engine is stopped after being warmed up during operation, the first fuel injection valve (4) is heated by the heat of the engine, and the temperature of the fuel filling the fuel reservoir chamber (36) increases. As a result, bubbles are generated and expand in volume, increasing the pressure, and when the pressure inside the fuel reservoir chamber (36) becomes higher than the pressure inside the combustion chamber, the outward opening valve (37) is caused to close by the second spring. (38) is opened against the
The fuel in the fuel reservoir chamber (36) easily leaks into the combustion chamber (
Become.

When this fuel leak occurs, problems such as the combustion chamber becomes rich in fuel and the spark plugs (26) (27) become wet, making it difficult to ignite and causing a misfire to occur.

In order to prevent such adverse effects, the fuel storage chamber (36)
It is necessary to reduce the pressure of the fuel, and a pressure reducing valve 05) and a pressure reducing passage 0ω are provided as means for reducing the pressure.The pressure is increased by the fuel pump (9), and the pressure is maintained at a pressure suitable for fuel injection by the pressure regulating valve 03). When the engine is stopped after warming up, the control unit (
Based on the command from 23), the pressure reducing valve 0ω is opened, and the fuel supply path 0 is prevented from escaping from the pressure reducing passage 06) to the atmospheric pressure in the fuel tank Oω via the drain passage 04).
21 and the fuel passage (31) of the first fuel injection valve (4) communicating therewith is reduced to be lower than the pressure in the fuel reservoir chamber (36), and at the same time the control unit (23 ), the electromagnetic coil (
35) is turned on to open the metering valve (33) intermittently against the first spring (34), and the pressure in the fuel reservoir chamber (36) is controlled by the metering spindle (35) in the fuel passage (31). 32) in the direction of the solid line arrow, the fuel is released to the depressurized fuel supply path 02), the pressure is reduced with a small current consumption, and the outward opening valve (
37) to prevent fuel from leaking into the combustion chamber.

At this time, if the pressure reducing valve (+51) is controlled so that the pressure inside the fuel supply passage θ is reduced to below the pressure required for fuel injection and then gradually reduced to atmospheric pressure, the fuel supply passage Hrm
Evaporation of fuel inside the tank can be suppressed.

As shown in FIG. 4, this pressure reduction control of the fuel reservoir chamber (36) is performed by detecting engine stoppage after warming up using an engine speed sensor (21), which is an engine stoppage detection means, and measuring the degree of engine heating by measuring the engine water temperature. It is detected by an engine water temperature sensor (22) which is a detection means, and the outputs of both sensors are controlled by a control unit (23) to open a pressure reducing valve (15) which is a pressure reducing means.

In addition, it is necessary to prevent the opening of the first fuel injector (4) facing the combustion chamber from being exposed to combustion gas and reducing its durability. It is configured to be blocked by

[Second Embodiment] Figs. 5 and 6 show another embodiment in which the pressure reducing means for reducing the pressure in the fuel reservoir chamber (36) is different, and Fig. 5 shows a rotary piston engine similar to Fig. 1. FIG. 6 is a detailed cross-sectional view of the first fuel injection valve (4a) similar to FIG. 2, and the same parts as in the first embodiment are given the same reference numerals. and explain.

This second embodiment differs from the above-described first embodiment in structure and operation only in the pressure reducing means for reducing the pressure in the fuel reservoir chamber (36), and everything else is the same as the first embodiment, so the same parts The explanation will be omitted and only the pressure reducing means will be explained.

As shown in Fig. 6, the pressure reduction port (43) is located in the fuel reservoir chamber (36).
) is provided to protrude through the assist air passage (40), and this pressure reduction port (43) is connected to the fuel tank 00) by a pressure reduction passage (16a), and this pressure reduction passage (16a) has a pressure reduction valve ( A control unit (15a) is interposed and receives outputs from the rotational speed sensor (21) and the engine water temperature sensor (22) when the engine is stopped after warming up.
23) sends a pulse signal to the pressure reducing valve (15a) to open it intermittently and release the pressure in the fuel reservoir chamber (36) to the atmospheric pressure in the fuel tank θ0) via the pressure reducing passage (16a). This gradually reduces the pressure, and this pressure reduction can prevent fuel from leaking into the combustion chamber from the outward opening valve (37).

In addition, before the engine warm-up is completed, the pressure reducing valve θ5) (15a
) is maintained in a closed state, so sufficient fuel is supplied from the beginning upon restart.

In the second embodiment, the pressure reducing valve (15a) may be of an open type instead of an intermittently open type (effects of the invention). By installing a pressure reducing means to prevent the accumulated fuel in the fuel injection valve that directly injects fuel into the combustion chamber from being heated by the engine heat and expanding in volume and increasing the pressure when the engine is stopped after warming up. , prevents fuel from leaking into the combustion chamber due to increased pressure, and eliminates ignition failures caused by fuel leaks that cause the mixture in the combustion chamber to become too rich or the spark plug to become wet. It is something.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall configuration of a fuel injection device for a low-rise engine as an embodiment of the present invention, and FIG. 1 is a detailed vertical cross-sectional view of the fuel injection valve, FIG. The figure is a block diagram showing the control for reducing the pressure in the fuel reservoir chamber of the first fuel injection valve, and FIG. 5 is a rotary engine showing another embodiment in which the pressure reducing means for reducing the pressure in the fuel reservoir chamber of the first fuel injection valve is different. FIG. 6 is a detailed longitudinal sectional view of the first fuel injection valve of FIG. 5. 1. Rotor housing 2. Rotor 4.4a...
First fuel injection valve 6...Second fuel injection valve 12...Fuel supply path 15.
15a... Pressure reducing valve (pressure reducing means) 16. 16a... Pressure reducing passage (pressure reducing means) 33... Metering valve 35... Electromagnetic coil 36... Fuel reservoir chamber 37... Outward opening valve patent Applicant Mazda Motor Corporation Agent/patent attorney Takashi Mihara (1 other person)

Claims (1)

[Claims] A fuel injection valve facing the combustion chamber is configured to include a metering valve that opens electromagnetically and an outwardly opening valve that supplies metered fuel to the combustion chamber, and when the engine is stopped, the fuel injection valve A fuel injection device for an engine, comprising a pressure reducing means for reducing the pressure in a fuel reservoir chamber formed between a quantity valve and an outward opening valve.