JPS61167116A - Auxiliary ignition type diesel engine - Google Patents

Abstract

PURPOSE:To obtain stable and better firing by disposing an electrode of an ignition plug in a concave provided on a lower portion of a cylinder head and orienting a portion of an injection hole of a fuel injection nozzle to the electrode unit. CONSTITUTION:A concave unit 20 whose cross section is chevron shaped is formed on a lower portion of a cylinder head 11, and an entire electrode unit 16 of an ignition plug 14 is oriented to a combustion chamber 13 under the condition where the electrode unit 16 is accommodated in the concave unit 20 and placed. And an injection nozzle 15 whose tip unit 15a is facing to the combustion chamber 13 is provided on an opposite side of the ignition plug 14, and on the tip unit 15a, plural injection holes 18 whose portions are oriented to the electrode unit 16 are formed. Therefore, strong swirl flow or squish flow generating during rising of a piston 12 is not splashed on the electrode unit 16 and blow-out of electric discharge can surely by prevented, and surer firing can be obtained by positive supply of partical injection fuel to the electrode unit 16.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in an auxiliary ignition type diesel engine in which spark ignition is performed by a spark plug disposed in the combustion chamber of a newly assembled direct injection type diesel engine.

Conventional Technology As is well known, diesel engines rely on the so-called compression ignition method, in which the air sucked into the cylinder is compressed to a high temperature, and fuel is injected into it in the form of a mist to self-ignite. It is difficult to ignite fuels with low cetane number, such as wide-cut diesel oil, ethanol, methanol, etc.

In addition, they generally have worse low-temperature startability than gasoline engines (,
There are also problems such as noise due to ignition delay at low temperatures.

Therefore, an auxiliary ignition type diesel engine has been proposed that utilizes an ignition device similar to that of a normal gasoline engine, as shown in FIG. 2, for example. To explain the outline, in a toroidal combustion chamber 3 formed at the upper end of a piston 2 at the bottom of a cylinder head 1 in a direct injection diesel engine,
An ignition plug 4 is installed instead of a glow plug, and the ignition plug 4
The fuel spray from the injection nozzle 5 is forcibly ignited by spark only regularly or at low temperatures where compression ignition is difficult (for example, 5AEpaper to 8
3058).

Problems to be Solved by the Invention However, in the above-mentioned conventional auxiliary ignition type diesel engine, the spark plug 4 fixed to the cylinder head 1
The electrode portion 6 of the diesel engine is shaped to protrude greatly into the combustion chamber 3, and even if an attempt is made to forcefully ignite it with the spark plug 4 as described above, a very strong swirl or squish flow will occur within the combustion chamber 3 of the diesel engine. exists and the flow velocity at the electrode portion 6 of the ignition plug 4 is high, making it difficult for discharge sparks to fly, and even if the spark does fly, it tends to blow out and stable ignition cannot be obtained. Furthermore, since the long electrode portion 6 of the spark plug 4 is exposed to the high temperature gas in the combustion chamber 3, heat resistance is reduced. Furthermore, in a small diesel engine, since the combustion chamber 3 is formed relatively small, the electric wire protruding into the combustion chamber 3 obstructs air flow such as swirl inside the combustion chamber 3, which deteriorates combustion. There are various problems such as:

Means for Solving the Problems In order to solve the above problems, the auxiliary ignition type diesel engine according to the present invention includes a recessed portion in the lower part of the cylinder head constituting a part of the combustion chamber, and a recessed portion inside the recessed portion. The present invention is characterized in that an electrode portion of the spark plug is disposed at the fuel injection nozzle, and a part of the nozzle hole of the fuel injection nozzle is formed to face the electrode portion.

Function: In this invention having the above-mentioned configuration, the electrode part of the ignition plug is housed in the recess provided in the lower part of the cylinder head, so that there is a strong swirl generated in the combustion chamber.・The squish flow is not directly sprayed onto the electrode part, and only a relatively weak swirl etc. that is sufficiently suppressed is applied.For this reason, the fuel injected to the electrode part is quickly ignited, and the squish flow is not directly sprayed onto the electrode part. This prevents sparks from blowing away, resulting in stable and good ignition.In addition, the electrode part is not exposed to high-temperature gas in the combustion chamber, improving heat resistance. Since the flow is not obstructed, combustion efficiency can be improved.

Example Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of essential parts showing an embodiment in which the present invention is applied to a direct injection diesel engine.

In the figure, 11 is a cylinder head, 12 is a piston that slides in the cylinder block 17 at the bottom of the cylinder head 11, and 13 is a toroidal combustion chamber formed with a notch in the upper end of the piston 12. A recessed portion 20 having a “h”-shaped cross section is formed in the lower part of the shilling head 11 constituting a part of the chamber 13, and the electrode portion 16 of the spark plug 14 is directed toward the combustion chamber 13 in this recessed portion 20. The entire electrode portion 16 is housed in the recess 20. Further, on the opposite side of the cylinder head 11 from the ignition plug 14, an injection nozzle 15 is provided with a tip 15a facing the combustion chamber 13. A plurality of nozzle holes 18 are formed in the tip 15a of the injection nozzle 15, some of which are directed toward the electrode section 16, and others of which are directed toward the combustion chamber 13.

Therefore, when fuel is injected from the injection nozzle 15 into the vicinity of the combustion chamber 13 and the electrode section 16 during the compression stroke of the piston 12, a high-voltage spark is discharged from the electrode section 16 of the spark plug 14 L later and becomes atomized fuel. Although it is forcibly ignited,
Since the strong swirl or squish flow generated during the upward movement of the piston 12 does not directly blow onto the electrode section 16 within the recessed section 20, the discharge is reliably prevented from being blown out.
Stable and reliable ignition can be obtained at all times. In particular, more reliable ignition can be achieved by actively supplying the partially injected fuel to the electrode portion 16. Further, since the electrode part 16 does not protrude into the combustion chamber 13, the heat resistance of the spark plug 14 can be improved, and even in a small diesel engine, the spark plug 14 can prevent air inside the combustion chamber 13. The flow is not obstructed and a strong air flow is always obtained, improving combustion efficiency.

Note that the fuel injection timing and ignition timing in this embodiment are set to appropriate values, respectively, depending on the operating state of the engine. Further, although the above embodiments have been shown to be applied to a toroidal type combustion chamber, it goes without saying that the present invention can also be applied to a shallow dish type or the like.

Effects of the Invention As is clear from the above explanation, in the auxiliary ignition type diesel engine according to the present invention, despite the strong air flow in the combustion chamber, stable and reliable ignition combustion is always achieved by the spark discharged from the ignition plug. This makes it possible to improve low-temperature startability through forced ignition, reduce idle noise, and operate with low cetane fuel.

In addition, since the spark plug electrode does not protrude into the combustion chamber,
Not only does the heat resistance of the spark plug improve, but the air flow within the combustion chamber is not obstructed and a strong swirl flow can be ensured, resulting in better combustion, improved fuel efficiency, and improved output.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main parts of an auxiliary ignition type diesel engine according to the present invention, and FIG. 2 is a sectional view showing the main parts of a conventional auxiliary ignition type diesel engine. L, 11... Cylinder head, 2.12... Piston, 3, 13... Combustion chamber, 4, 14... Spark plug, 5゜15... Injection nozzle, 6, 16... Electrode Department, 18・
...Nozzle hole, 20... hollow part.

Claims (1)

[Claims] (1) In an auxiliary ignition diesel engine equipped with an ignition plug for spark ignition in a combustion chamber in which a fuel injection nozzle is installed, a recess is provided in the lower part of the cylinder head that constitutes a part of the combustion chamber, and the recess is An auxiliary ignition type diesel engine, characterized in that an electrode portion of the spark plug is disposed within the spark plug, and a part of the nozzle hole of the injection nozzle is formed to face the electrode portion.