JPH02115569A - Fuel injection device for engine - Google Patents

Abstract

PURPOSE:To make an air pump unnecessary for feeding assist air by providing an assist air passage for connecting the combustion chamber of one cylinder in a fuel injection state with that of the other cylinder, which is in a compression stroke at the inner pressure higher than that of the former cylinder. CONSTITUTION:Assist air control valves 16, 16a are controlled by a control unit 23 to be opened only on fuel injection of a fuel injection valve 4 or 4a in the region of low load/low rotation. As shown, in cylinders R1 and R2, the intake stroke and compression stroke are overlapped to each other and, when one cylinder is subjected to the fuel injection in the intake stroke or in the intial compression stroke, compression air or compression mixture, that is, assist air at the inner pressure higher than this cylinder is fed from the other cylinder in a compression stroke. In addition, an assist air changeover valve 17 is used to intake atmospheric air as the assist air in a-low load/low rotation region.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel injection device for an engine that supplies assist air to a fuel injection valve that injects fuel directly into a combustion chamber of the engine.

(Prior art) Conventionally, fuel is injected directly into the vicinity of the spark plug in the combustion chamber of an engine to stratify a mixture with an appropriate concentration to improve ignition performance, making the overall air-fuel ratio leaner and improving fuel efficiency. For example, Japanese Patent Application Laid-Open No. 1983-14
It is known as described in Japanese Patent Publication No. 7924%.

In this case, especially in fuel injection in low load and low rotation range,
Since it is necessary to atomize the fuel with assist air and create a mixture with an appropriate air-fuel ratio, assist air is required during fuel injection, and in the above publication, the assist air is extracted from the intake passage using an air pump and combusted together with the fuel. It is supplied to the room.

However, the conventional assist air supply method requires an air pump, and since engine output is used to drive this air pump, the fuel efficiency of the engine decreases. The problem is that an electromagnetic clutch is required to stop the system, which complicates the device, and the pressure of the assist air to be supplied is
There has been a problem that the internal pressure of the cylinder where fuel is injected is either too high or too low, making it difficult to stabilize the operating state.

(Objective of the Invention) This invention was made to solve the above-mentioned conventional problems, and does not require an air pump to supply assist air, and always supplies pressure assist air that is adapted to the cylinder pressure during fuel injection. The object of the present invention is to provide a fuel injection device for an engine that can be supplied.

(Structure of the Invention) To achieve the above object, this invention is an engine having a plurality of cylinders in which fuel is injected with assist air from a fuel injection valve facing the combustion chamber of the engine during the intake process or the early stage of the compression process. This fuel injection device for an engine is equipped with an assist air passageway that connects the combustion chamber of another cylinder that is in the compression stage and whose internal pressure is higher than that of the cylinder in which fuel is injected.

According to the above configuration, an air pump is required to obtain the assist air pressure because assist air consisting of compressed air or a compressed mixture is supplied from other cylinders that are in the compression process slightly higher than the internal pressure of the cylinder that injects fuel. Therefore, the device is simple, and since the pressure difference between the cylinder injecting fuel and the assist air can be supplied almost constant regardless of the magnitude of the engine load, the operating condition can always be kept stable.

(Example) Hereinafter, this invention will be described in detail based on an example shown in the drawings.

Figure 1 shows the overall configuration of a fuel injection device that includes a first fuel injection valve that injects fuel directly into the leading side of the combustion chamber of a low-return piston engine, and a second fuel injection valve that injects fuel into the intake passage. Figure 2 is a vertical cross-sectional view showing details of the first injection valve, in which (1) is a rotor housing having an operating chamber (la) with a two-section peritrochoid-shaped inner circumferential surface; Almost triangular rotor (2) in chamber (1a)
is supported by an eccentric shaft (3) and rotates eccentrically, and the first fuel injection valve (4) injects fuel directly to the leading side during compression when the rotor (2) in the working chamber (1a) is in the illustrated state. is attached to the side housing (not shown) with the injection port facing the combustion chamber, and the intake boat of the intake passage (5) is connected to the intake bow 1- (24) that opens into the working chamber (la). A second fuel injection valve (6) that injects fuel is provided at a position close to (24). A throttle valve (7) and an air flow meter (8) are arranged in this order in the intake passage (5) on the upstream side of the second fuel injection valve (6), and (9) is a fuel pump that starts from the fuel tank 0ω. Fuel is inhaled through a fuel suction passage (11), and through a fuel supply passage connecting this fuel pump (9) with a first fuel injection valve (4) and a second fuel injection valve (6). It supplies fuel to the first fuel injection valve (4) and the second fuel injection valve (6). This fuel supply passage (+21 is provided with a pressure regulating valve side) to regulate the pressure in the fuel supply passage θ to a pressure suitable for fuel injection, and drain excess fuel through the drain passage 04. It should be returned to tank Oo).

05) is the assist air supply path, and the first fuel injection valve (4)
The assist air control valve (16) is provided in communication with the combustion chamber of another cylinder (not shown) which is in the compression stage and whose internal pressure is higher than that of the cylinder injecting fuel. , an assist air switching valve θ, and a group of check valves θ are sequentially provided along the flow direction of the assist air.
) are connected. The assist air supplied through the assist air supply path 05) is supplied through the first fuel injection valve (4).
) is supplied into the combustion chamber before and after fuel injection to atomize the fuel into a combustible mixture, as well as to clean the combustion chamber and eliminate residual burnt gas. I will explain in detail.

Q (D is a throttle sensor that detects the opening degree of the throttle valve (7) corresponding to the engine load, (21)
(22) is an engine water temperature sensor that determines the engine heating state; (23) is a control unit that is connected to the throttle sensor C! [D, engine speed sensor (21), and engine water temperature sensor (22)
), the timing and injection amount of fuel injection of the first fuel injection valve (4) and the second fuel injection valve (6) are controlled, and the assist air control valve aω is controlled. 1 controls the timing and amount of assist air supplied to the fuel injection valve (4). (25) indicates an exhaust port, and (26) and (27) indicate a spark plug.

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 to the fuel passage (30) in the axial direction following this fuel inlet (30).
A metering spindle (32) is installed in this fuel passage (31) by engaging a cylindrical magnetic body (32a) at its upper end. The first spring (34), which forms a metering valve (33) that opens and closes the passage (31) and pressurizes the upper end of the magnetic body (32a), always urges the metering spindle (32) downward. The metering valve (33) is closed, and an electromagnetic coil (35) is incorporated in the metering spindle (32), and when the electromagnetic coil (35) is turned on, the magnetic material (33) is closed.
2a) so that the metering spindle (32) releases the first spring (
34) to open the metering valve (33).

A fuel reservoir chamber (36) is formed below the metering valve (33), and this fuel reservoir chamber (36) is connected to the metering valve (33).
When opened, it communicates with the fuel passage (31). The lower end of this fuel reservoir chamber (36) communicates with the outer valve (37) provided at the lower end of the first fuel injection valve (4).
) is closed by the second spring (38) with its opening facing the combustion chamber, and from this state the electromagnetic coil (35) is turned off.
When the fuel is fed into the fuel reservoir chamber (36) and the pressure increases, the outer valve (37) is opened against the second spring (38) and the fuel is combusted. It is sprayed indoors.

(39) is an assist air inlet, which communicates with the assist air supply path 0ω, which will be described in detail later, and is formed by surrounding the outer periphery of the fuel passage (31), the fuel reservoir chamber (36), and the outer valve (37). The air 1ff that corresponds to the front of the outer valve (37) passes through the assist air passageway (40) shown in the direction of the broken line arrow.
Assist air is blown into the combustion chamber before and after fuel injection, including the time of fuel injection, from an opening (42) provided in the road outer wall (41).
This turns the fuel into a combustible mixture during fuel injection.

Figure 3 shows the first fuel injection valve (4) and the second fuel injection valve (6).
The diagram shows the usage range of the first fuel injector in the low-load, low-speed range (A), where the horizontal axis shows the engine speed and the vertical axis shows the opening of the throttle valve (7) corresponding to the engine load. Only (4) injects fuel along with assist air to the leading side of the compression process, which stratifies a rich air-fuel mixture near the spark plugs (26) and (27) to facilitate ignition. The other part is the intake passage (5
), resulting in a lean air-fuel mixture consisting mainly of air from the engine (8), which improves fuel efficiency in the low-load, low-speed range (8), such as during idling, where much output is not required.

In addition, in the high-load, high-speed region (B), the second fuel injection valve (6) is mainly used, and the first fuel injection valve (4) is placed on the leading side of the combustion chamber to improve ignition performance, and the assist air control It is used auxiliary with the valve 06) closed to cut off the assist air to stratify the fuel around the spark plugs (26) and (27) to ensure reliable ignition.

In addition, the opening of the first fuel injector (4) facing the combustion chamber is closed by the rotor (2) just before ignition to prevent it from being exposed to high-temperature combustion gas and reducing its durability. It is configured so that it can be removed.

Next, based on the low-load, low-speed region (A) shown in Fig. 3 above, the supply of assist air to the first fuel $1 injection valve (4) is shown in Figs. 4, 5, and 6. Let me explain based on this.

Figure 4 shows a two-cylinder rotary piston engine.
The assist air supply paths θ5) (15a) connected to the first fuel injection valves (4) (4a) provided in the cylinders (Rt) (Rz), respectively, are connected to the adjacent cylinders (R2) and (R1). ), and in this case cylinders (R1) and (Rt) have their intake strokes and compression strokes overlapping each other, so one cylinder is connected to the other cylinders during the intake stroke or at the beginning of the compression stroke. At the time of injection, compressed air or a compressed mixture serving as assist air having a higher internal pressure than this cylinder can be supplied from the other cylinder in the compression process.

FIG. 5 is a diagram showing in detail the assist air supply path shown in FIG. an assist air supply path (15a) connecting the fuel injection valve (4a) of the cylinder (R2) and the inside of the cylinder (R3);
(16a) are respectively provided, and the air intake I is provided downstream of this assist air control valve 06) (16a)
Q! (19a) is branched, and at this branch point there is a check valve Q8) (18a) located downstream of the assist air switching valve 07) (17a) and close to the first fuel injection valve (4) (4a). Each is provided.

The assist air control valve Q6) (16a) is controlled by the control unit (23), and the fuel injection valve (Q6) (16a) is controlled by the control unit (23).
4) or (4a) is the low load low rotation area (A) in Figure 3.
It opens only when fuel is injected.

FIG. 6 is a diagram showing the configuration of the assist air switching valve 07).
A spring (173,) provided in the assist air supply path 09 near the intersection of the assist air supply path 0 port and the atmospheric suction path 09)
The first valve (17,) is closed by the pressure of
17v□), and when the first fuel injection valve (4) is in the low-load, low-speed region (A) in Fig. 3, the assist i/air control valve θω is open, and the P arrow is applied to the assist air supply ma■. Assist air consisting of compressed air or a compressed mixture with a pressure higher than the atmospheric pressure enters from the direction of the first valve (1).
7v,) opens against the spring (17,,) (, then the second valve (17v□) closes against the spring (17s1) due to the pressure of the assist air, and the assist air at a pressure higher than atmospheric pressure flows in the direction of arrow Q and is supplied to the first fuel injection valve (4).

When the engine is at an extremely low load and low rotation speed and the pressure of the assist air passing through the assist air supply paths θ is below atmospheric pressure, the first valve (17, I) is closed by the spring (17, , ); Since the pressure on the downstream side also decreases, the second valve (1
7v□) is opened by the pressure of the cover spring (17s2), and the atmosphere is sucked in from the atmosphere intake passage 09), and the first fuel injection valve (4
) is supplied with air. When the first fuel injection valve (4) finishes fuel injection and the cylinder (R1) enters the compression process and the internal pressure increases, the assist air passage (4) inside the first fuel injection valve (4) increases.
When pressure reaches the assist air supply path (+5) through the assist air supply path (+5), the check valve 08) prevents backflow and prevents the pressure in the cylinder (R1) from escaping.

In this way, in the high-load, high-speed region within the low-load, low-speed region (A) shown in FIG. is supplied as assist air, and in this case, the pressure difference between the internal pressure of the cylinder where fuel is injected and the assist air can be kept at an ideal, almost constant value. It is sucked in as assist air.

The assist air switching valve 07) may be replaced with an electromagnetically switched three-way valve, which is convenient in the above embodiment.
Although a rotary piston engine that can be implemented has been shown, it is also possible to implement a multi-cylinder reciprocating engine.

(Effects of the Invention) According to the fuel injection device for an engine according to the present invention described above, in a low-load, low-speed operation region, assist air is supplied at the time of fuel injection from inside another cylinder in the compression process. By doing so, it is possible to always supply assist air, which is higher than the internal pressure of the cylinder when fuel is injected, with a nearly constant pressure difference, and it is possible to maintain stable engine operating conditions. is unnecessary, and the configuration can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the entire tank bottom of a combustion injection device for a rotary piston engine as an embodiment of the present invention, and FIG. 1. A detailed vertical cross-sectional view of the fuel injector, Figure 3 shows the first fuel injector that injects fuel directly into the leading side of the combustion chamber, and the second fuel injector that injects fuel into the intake passage. Figure 4 is a schematic diagram of the assist air supply route to be supplied to the first fuel injection valve, and Figure 5 is a detailed diagram of the assist air supply route shown in Figure 4. , FIG. 6 is a detailed sectional view of the assist air switching valve interposed in the assist air supply path. l...Rotor housing 2...4...First fuel injection valve 6...Second fuel injection valve 15...Assist air supply path 16...Assist air control valve 17...Assist air switching valve R1, R2... Cylinder rotor patent Applicant: Mazda Motor Corporation agent/patent attorney Takashi Mihara (1 other person)

Claims (1)

[Scope of Claims] In a fuel injection device for an engine having a plurality of cylinders, which injects fuel with assist air from a fuel injection valve facing a combustion chamber during an intake process or an early stage of a compression process, a cylinder to which fuel is injected. What is claimed is: 1. A combustion injection device for an engine, comprising an assist air passageway connecting a fuel injection valve and a combustion chamber of another cylinder in a compression process having a higher internal pressure than the cylinder in which fuel is injected.