JPS62191616A - Fuel injection type engine - Google Patents

Abstract

PURPOSE:To restrain the thermal effect of high temperature exhaust gas on an injection nozzle to prevent carbide from deposition said nozzle by disposing the fuel injection nozzle directed to the central portion of a combustion chamber intermediate between a plurality of intake ports in the combustion chamber having an ignition plug disposed in the central portion. CONSTITUTION:A cylinder head 5 is formed with a nozzle hole 21 opening to the upper portion of a combustion chamber 6, and a fuel injection nozzle 26 is mounted in this nozzle hole 21 to project its end therein. This injection nozzle 26 is disposed in the cylinder head portion between intake ports 7, 7a, while being provided to be directed to an ignition nozzle 6a disposed in the opposite side valve bridge portion 5a and the central portion of combustion chamber 6. Also, the nozzle hole 21 is provided in the port 21a with a controlling valve 22 for controlling communication between the combustion chamber 6 and the nozzle hole 21. This controlling valve 22 is opened and closed through a rocker arm 24 by a cam shaft 13 to be opened from the latter period of intake stroke to the end period of compression stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in a fuel injection engine configured to inject fuel into a combustion chamber.

(Prior Art) In fuel injection engines, engines that perform so-called in-cylinder injection, in which fuel is directly injected and supplied into a combustion chamber, are conventionally known. This in-cylinder injection has less influence of agitation caused by the intake air flow than so-called port injection, which injects fuel within the intake passage. Therefore, when fuel is supplied in this way, it is easy to stratify the fuel, causing high concentrations of fuel near the spark plug. A concentrated air-fuel mixture layer can be formed, and ignitability can be improved.

Therefore, by utilizing this in-cylinder injection, it is possible to effectively achieve a lean engine and improve fuel efficiency. However, this method requires the fuel injection nozzle to be placed in the combustion chamber where the temperature gets high, so there is a problem that some of the fuel may carbonize and adhere to the nozzle tip, making it impossible to properly supply fuel. be.

In order to solve this problem,
In the publication, a recess opening for combustion is formed in the cylinder head, a fuel injection nozzle is arranged in this recess, and
A control valve is provided to control the communication between this recess and the combustion chamber, and this control valve is closed when not injecting fuel to cut off communication between the recess and the combustion chamber so that the nozzle tip is not directly exposed to flame. A fuel injection type engine is disclosed in which the fuel injection valve is protected in this manner.

(Problem to be Solved) In the structure disclosed in the above-mentioned Japanese Utility Model Publication No. 58-154825, the injection nozzle is isolated from the combustion chamber except during fuel injection, and the injection nozzle is isolated from the thermal shape of the combustion chamber. Since it is protected, the problem of carbide adhesion to the nozzle tip can be alleviated to some extent.

By the way, when performing in-cylinder injection, it is desirable to perform stratification so that a highly concentrated air-fuel mixture is formed near the spark plug. It is advantageous in terms of layout to arrange the spark plug so that fuel is injected toward the spark plug. However, when arranged in this way, the thermal influence of high-temperature exhaust gas is strong, carbide tends to adhere easily, and the durability of the injection nozzle is also unfavorable.

According to this method, the degree of freedom in layout is extremely high, especially for engines with multiple air ports; 1. This problem becomes serious as it has to be placed closer to the exhaust port.

(Means for Solving the Problems) The present invention has been constructed in consideration of the above problems, and is used in a fuel injection engine that has a plurality of intake ports and performs in-cylinder injection. It is an object of the present invention to provide a fuel injection type engine which can solve the problem of adhesion, can stratify the air-fuel mixture in the central part of a combustion chamber, and can therefore perform proper fuel injection. The engine according to the present invention includes a plurality of intake ports opening into a combustion chamber, a fuel injection nozzle for injecting and supplying fuel into the combustion chamber, and a spark plug disposed in a central part of the combustion chamber, wherein the fuel injection nozzle is connected to the combustion chamber. It is characterized by being located in the middle of the intake port and directed toward the center of the combustion chamber.

In the present invention, preferably, the fuel injection nozzle is disposed so that its tip protrudes into a recess, that is, a nozzle hole, formed in the cylinder head so as to be continuous with the combustion chamber, and
A control valve is provided to control communication and isolation between the nozzle hole and the combustion chamber. In this case, the control valve is adapted to close after the end of the injection period, preferably just before ignition.

Furthermore, in a preferred embodiment of the present invention, the nozzle holes of each cylinder are communicated with each other by a communication path.

(Operations and Effects of the Invention) According to the present invention, since the fuel injection nozzle is disposed at an intermediate position between a plurality of intake ports, it is less exposed to the thermal effects of high-temperature exhaust gas, and therefore, carbide adhesion is reduced. You can solve the problem.

In this case, the fuel injection nozzle is oriented so that fuel is injected toward the spark plug located in the center of the combustion chamber, so a highly concentrated mixture can be generated near the spark plug, resulting in good combustion. It is possible to ensure sex. In a preferred embodiment of the present invention, the injection nozzle is disposed in a nozzle hole that is formed continuously in the combustion chamber, and at least during the ignition timing, the injection nozzle is isolated from the combustion chamber and protected. , the thermal form η2 from the combustion chamber can be further reduced, thereby effectively solving the problem of carbide adhesion to the nozzle tip.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to FIGS. 1 to 3, the engine 1 of this example is a four-cylinder engine, and each cylinder has two pistons inside.
The cylinder block 4 is provided with a cylinder bore 3 in which the cylinder slides back and forth, and a cylinder head 5 is combined with the cylinder block 4. cylinder head 5
The lower recess formed in the cylinder bore 3 and the space above the piston of the cylinder bore 3 constitute a combustion chamber 6. A spark plug 6a faces the combustion chamber 6, and two intake ports 7.
7a and one exhaust port 8 are open, and these ports 7.7a and 8 are connected to an intake valve 9.9 and an exhaust valve 1.
0 are combined respectively.

An intake passage 11 and an exhaust passage 12 communicate with the intake port 7.7a and the exhaust port 8, respectively. In this case, as shown in FIG. 2, in the intake passage 11, a branch intake passage 11a is formed on the upstream side of the throttle valve 30, and further branched on the downstream side of the throttle valve 30 to form two branch intake passages 11b. , IIC are formed, respectively. The branch intake passages 11a and llb communicate with the intake port 7, and the branch intake passage 11C communicates with the intake port 7a. That is, in the structure of this example, intake air is routed through three intake passages 11a111b and II depending on the driving conditions.
c through any or all of the two intake ports7.
It is introduced into the combustion chamber 6 via 7a. Further, a valve mechanism is disposed in the upper part of the cylinder head 5, and the valve mechanism includes a camshaft 13 and a rocker arm for the intake cylinder driven by a cam (not shown) of the camshaft 13. 14, Exhaust valve rocker arm 15.11, and a rocker shaft 16.17 that supports the rocker arm 14.15 in a rotatable manner. The end bar 1 of each rocker arm 14,15 rests on the top of the valve stem 9a, 10a of the intake and exhaust valves. Holding members 9b and 10b are attached to one part of the valve stem 9a and loa, and this holding member 9b
, lOb respectively support springs 18 and 19 arranged between them and the cylinder head 5. Further, a cylinder head cover 20 is attached to the upper part of the cylinder head 5 to cover the valve mechanism. As shown in FIGS. 2 and 3, a nozzle hole 21 is provided in the cylinder head 5 so as to open at the upper part of the combustion chamber 6, and a nozzle hole 21 is provided in the cylinder head 5 so that the tip thereof protrudes into the nozzle hole 21. A spray nozzle 26 is attached. In this case, the fuel injection nozzle 26 is arranged in the cylinder head part between the intake port 7 and the intake port 7a, and the ignition nozzle 6a is arranged in the center of the valve bridge part 5a and the combustion chamber 6 on the opposite side.
The fuel is oriented and arranged so that fuel is injected in the direction of. Port 21a of this nozzle hole 21
A control valve 22 for controlling communication between the combustion chamber 6 and the nozzle hole 21 is combined with the nozzle hole 21 . A spring 23 is compressed between the cylinder head 5 and the pressing member 22b at the tip of the valve stem 22H of the control valve P22. The control valve 22 is connected to the camshaft 1 via the rocker arm 24.
3 opens and closes the port 21a of the nozzle hole 21.

Also, referring to FIG. 3, the nozzle hole 21 of each cylinder
A communication path 25 is formed to communicate with each other. The fuel injection from each fuel injection nozzle 26 is preferably controlled by a controller 29 including a microcomputer, and the controller 29 is supplied with signals representing engine speed, engine load, and crank angle. Each is manually powered.

In the following, the control of this example will be explained with reference to FIGS. 4 and 5.

FIG. 4 shows a flowchart of fuel injection control in the engine of this example.

Referring to FIG. 4, the controller 29 calculates the fuel injection amount based on the engine speed and load input manually. Further, the fuel injection timing is calculated based on the crank angle. Next, the controller 29 determines whether each cylinder has reached the injection timing calculated above, and when the injection start timing has arrived, it sends a command signal corresponding to a predetermined fuel injection amount to the injection nozzle. output and operate the injection nozzle. FIG. 5 shows the opening timing of the control valve 22 of each cylinder, the injection timing, and the pressure change in the nozzle hole 21. The ignition order of the engine in this example is around 1 of 1-3-4-2, so fuel injection is performed sequentially starting with Ifli'i.

In this case, the control valve 22 opens from the latter half of the intake stroke to the end of the compression stroke, and fuel injection starts after the control valve 22 opens in the latter half of the intake stroke, and ends in the middle of the compression stroke. . The pressure in the nozzle hole is controlled by the control valve 22.
When the piston opens, the cylinder is in the intake state, so the pressure drops rapidly, and when the piston begins to rise during the compression stroke, it reaches an upper limit. Immediately after the control valve 22 closes, it maintains a high pressure in the latter half of the compression stroke. In the structure of this example, for example, when the first cylinder is in the injection period, the control valves 22 of the other cylinders are closed, and the nozzle hole 21 is isolated from the combustion chamber 6. Therefore, high pressure remains in the nozzle hole 21, and this pressure is transferred to the nozzle hole 2 of the first cylinder, where the pressure has decreased by opening the control valve 22, via the communication passage 25.
1 will be introduced. As a result, an intake air flow from the nozzle hole 21 toward the combustion chamber 6 is generated in the nozzle hole of the first cylinder, which promotes the flow of fuel injected from the injection nozzle 26 into the nozzle hole 21 into the combustion chamber 6 and atomization. do. In this case, since the fuel is injected toward the ignition nozzle 6a and the valve bridge portion 5a, a highly concentrated air-fuel mixture layer is formed near the upper spark plug, thus improving ignitability. . In the structure of this example, there are two fuel injection nozzles 26.
Since it is arranged in the cylinder head part between the two intake ports 7.7a, it is possible to suppress the thermal influence on the exhaust side, and the fuel injection nozzle has the control valve 2.
Since the nozzle is isolated from the combustion chamber within the nozzle hole by 2, the problem of carbide adhesion to the nozzle tip does not occur. Furthermore, since a part of the injected fuel collides with the valve bridge portion 5a and cools this portion, the valve bridge portion does not deteriorate due to heat. In this example, fuel is injected from the latter half of the intake stroke to the compression stroke.
If a nozzle with a short injection period is used, or depending on the operating conditions, the injection may be performed only during the compression stroke.

[Brief explanation of drawings]

FIG. 1 is a top sectional view of an engine according to an embodiment of the present invention, FIG. 2 is a schematic view of the engine shown in FIG. 1 as seen from below, and FIG. 4 is a flowchart of fuel injection control according to the present invention, and FIG. 5 is a graph showing the relationship between nozzle hole pressure change, control valve opening period, and injection period in fuel injection control. 1... Engine, 2... Piston, 4... Cylinder block, 5... Cylinder head 13... Camshaft, 14.15 ...Rocker arm, 21...
...Nozzle hole, 25...Communication path, 26.
...Fuel injection nozzle, 29...Controller. Figure 2 Figure 4

Claims (1)

[Claims] The combustion chamber includes a plurality of intake ports that open into a combustion chamber, a fuel injection nozzle that injects and supplies fuel into the combustion chamber, and a spark plug that is disposed in the center of the combustion chamber, and the fuel injection nozzle is disposed in the middle of the intake port. A fuel-injected engine characterized by a fuel-injected engine that is oriented toward the center of the combustion chamber.