JPS6357814A - Direct injection type internal combustion engine - Google Patents

Abstract

PURPOSE:To ensure a constant combustion state, by providing a combustion chamber equipped with a main chamber section and the sub-chamber section connected via an orifice to said main chamber section, and also providing within the main chamber section a glow plug to ignite evaporated fuel gas. CONSTITUTION:A semi-spherical concavity 18 and the depression 19 of a nearly toroidal curve connected via nearly tapered opening 26 to said concavity 18 are formed in a cylindrical head 16 and, between these sections and a depressed piston-shape surface 20, a main chamber section 24, that is a part of a combustion chamber 22, is schemed. An injection nozzle 28 is provided in the center position of the depression 19, and a glow plug 32 on a side section thereof, respectively. On the other side of the depression 19, the sub-chamber section 34 consisting of a heat insulating layer 36 made of ceramics or the like is provided so as to be connected via orifice 38 to the main chamber section 24. Pressure in the sub-chamber section 34 is developed by combustion gas produced within the main chamber section 24 so as to cause combustion within the sub- chamber section 34, thereby the combustion gas in the sub-chamber section 34 being allowed to blow out at high speed into the main chamber section 24.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a direct injection internal combustion engine, and particularly relates to a direct injection internal combustion engine.
While using volatile fuels such as alcohol and diesel oil,
This invention relates to something that has been improved to ensure good combustion conditions even when a low compression ratio is employed.

[Prior art] As a conventional direct injection internal combustion engine, Japanese Patent Application Laid-Open No. 61-899
There is one described in Publication No. 19. This internal combustion engine has a main combustion chamber and an auxiliary combustion chamber as combustion chambers, and fuel is sprayed not only into the main combustion chamber but also into the auxiliary combustion chamber. Then, the sub-combustion chamber is ignited and combusted before the main combustion chamber, and the combustion gas spouted out thereby causes the main combustion chamber to combust and ignite.

In this type, especially when a low compression ratio is adopted, it is easy to cause lt fire lag in the main combustion chamber, and therefore, there is a possibility that it is difficult to sufficiently suppress the pressure rise in the main combustion chamber.

In response to this, the applicant proposed a new internal combustion engine in Japanese Patent Application No. 61-125279.

Similar to the prior art described above, this internal combustion engine has a main chamber equivalent to the main combustion chamber and a small chamber equivalent to the auxiliary combustion chamber as combustion chambers, and the fuel is supplied not only to the main chamber but also to the small chamber. It is also equipped with a spray nozzle and spark plug.

According to this internal combustion engine, it becomes possible to employ a low compression ratio by spark ignition. The combustion gas from the ignited blue flame in the main chamber increases the pressure in the small chamber, and the air-fuel mixture in the small chamber self-ignites after a delay. The pressure in the small chamber increases rapidly due to this ignition delay, and a high-speed airflow is ejected into the main chamber. This jet stream quickly burns the unburned fuel in the main chamber. In the main chamber, combustion occurs smoothly from the start of combustion by one ignition to the combustion promotion and completion by the jet from the small chamber.
Unlike the prior art described above, there is no pressure increase due to ignition delay in the main chamber.

[Problems to be Solved by the Invention] However, when using a fuel with poor vaporizability, it is difficult to reliably form a combustible air-fuel mixture at the time of spark discharge. In particular, two-stroke engines have a problem in that gas exchange is unstable at low speeds and misfires are likely to occur.

An object of the present invention is to more reliably guarantee good combustion conditions by reliably and easily igniting the main chamber.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a main chamber and an 8-spin which is substantially smaller than the main chamber, and
A direct injection type having a combustion chamber including a small chamber communicating with the main chamber through an orifice, and an injection nozzle disposed in the main chamber to supply fuel to the main chamber and the small chamber. In an internal combustion engine, there is a glow plug for igniting a mixed gas formed by vaporized fuel in the main chamber, and the ignition causes combustion in the main chamber, and the combustion increases the pressure in the small chamber. A glow plug was disposed in the main chamber to cause combustion in the small chamber, thereby producing a high-velocity flow from the small chamber through the orifice toward the main chamber.

[Function] Fuel is supplied to the main chamber from the injection nozzle and vaporizes, forming a combustible mixture with the passage of time, and at the same time, the combustible mixture is heated by a glow plug that is energized and heated.
It is ignited before the small chamber.

[Example code] The present invention will be explained below based on embodiments shown in the drawings.

A first embodiment is shown in FIGS. 1-3. code 1
0 is a two-stroke, crank chamber compression scavenging diesel engine. The engine IO has an engine block 12, a piston 14, and a cylinder head 16.

The piston 14 opens and closes a scavenging boat and an exhaust boat (not shown) formed on the inner surface of the cylinder for gas exchange.

On the other hand, the cylinder head 16 is provided with a hemispherical recess 18 and a generally toroidal curved recess 19 that communicates with the recess 18 through a generally tapered opening 26 . A main chamber portion 24, which is a part of the main chamber portion 24, is formed.

An injection nozzle 28 is provided at the center of the depression 19, and a glow plug 32 is provided at the side. Furthermore, the depressed portion 19
A small chamber fi is formed from a heat insulating material layer 36 such as ceramic on the other side, and communicates with the main chamber 24 through an orifice 38, as shown in FIG. 'f! There are 34 locations. Injection nozzle 2
A portion of the fuel injected from 8 is directed to the orifice 38 and another portion is directed to the glow plaque 32.

FIG. 3 is a glow plug heating circuit.

In the figure, 40 is a thermistor, 42 is a switch, 44 is a battery, and 45 is an energization amount control circuit.

The thermistor 40 senses the temperature of the engine and acts on the energization amount control circuit 45. Glow Plaque 3 when the temperature is high
The amount of current applied to 2 is decreased, and conversely when it becomes low, the amount of current applied is increased. This electric circuit has a simpler structure than an electric circuit that controls the ignition timing of the spark plug for each combustion cycle.

The operation of the above embodiment will be explained below.

Fresh air is introduced into the combustion chamber 22, and when the piston 14 approaches top dead center, fuel is injected from the injection nozzle 28. The fuel injected into the glow plug 32 is vaporized, and when the mixture with fresh air becomes flammable, it is reliably ignited by the glow plug 32, and combustion begins at this position. On the other hand, a portion of the fuel is introduced into the small chamber 34 via the orifice 38. Since the wall surface of the small chamber portion 34 is formed by the heat insulating material layer 36, the temperature of the wall surface is maintained high.
Fuel vaporization is promoted.

The air-fuel mixture in the small chamber 34 is affected by the combustion in the main chamber 24, and when the pressure rises enough, it self-ignites, and the pressure in the small chamber 34 rises rapidly, and conversely, the air-fuel mixture is ignited through the orifice 34. A high-speed, high-temperature gas stream is injected toward the main chamber 24. This injection promotes combustion within the main chamber 24, thereby ensuring complete combustion during each combustion cycle.

A second embodiment of the present invention is shown in FIG. 4, and in addition to the first embodiment, a spark plug 46 is disposed in the main chamber 24. The air-fuel mixture is also ignited by the spark plug 46, and at high speeds when it is increasingly necessary to provide the correct ignition timing, a better combustion condition is provided than with glow sparks alone.

5, 6 and 7 respectively show a third, fourth and fifth embodiment of the present invention. These embodiments apply the present invention to a four-stroke engine.

In the figure, 36A and 36B are 1tFT thermal material layers divided into two,
Reference numeral 48 indicates an intake valve, 50 indicates an intake passage, and 52 indicates a bolt.The same parts as in the previous embodiment are designated by the same reference numerals.

In the third embodiment, both the main chamber 24 and the small chamber 34 are provided in the piston 14.

In the fourth embodiment, only the main chamber 24 is connected to the piston 14.
The small chamber portion 34 is located on the cylinder head 16 side.

In the fifth embodiment, the small chamber 34 is disposed in the piston 14, and the main chamber 24 is disposed on the cylinder head 16 side.

In either case, the main chamber first ignites and burns due to the glow plug 32, and then the small chamber 34 into which fuel is injected through the orifice 38 self-ignites. This provides good combustion conditions.

[Effects] As explained above, according to the present invention, the glow plaque is disposed within the main chamber, so even if there is variation in gas exchange in the main chamber, ignition can be reliably ignited, and a better result can be achieved more reliably. It can provide a good combustion condition.

[Brief explanation of the drawing]

Figure i1 is a sectional view showing only the engine part in the first embodiment of the present invention, Figure 21M is a schematic view taken along the line ■-■ in Figure 1, Figure 3 is a glow plaque heating circuit, and Figure 4 is a diagram showing the glow plaque heating circuit. Schematic IA showing the second embodiment of the present invention, Fig. 5 is a sectional view showing the main parts of the engine in the third embodiment of the present invention,
FIG. 7 is a cross-sectional view showing a main part of an engine according to a fourth embodiment of the present invention, and FIG. 7 is a cross-sectional view showing only a main part of an engine according to a fifth embodiment of the present invention. 10...Engine 24...Main chamber 28...Injection nozzle 32...Claw plaque 34...Small chamber 38...Orifice agent Patent attorney Yoshiyuki Inaba 9'v: J8-High 8

Claims (3)

[Claims] (1) having a combustion chamber including a main chamber and a small chamber having a volume substantially smaller than the main chamber and communicating with the main chamber through an orifice; A glow plug for igniting a mixed gas formed by vaporized fuel in the main chamber in a direct injection internal combustion engine in which an injection nozzle for supplying fuel to a fuel chamber and a small chamber is arranged in a main chamber, The ignition causes combustion within the main chamber, and the combustion increases the pressure within the small chamber to cause combustion within the small chamber, thereby causing a high-speed flow from within the small chamber to the main chamber through the orifice. A direct injection internal combustion engine characterized by a glow plug disposed inside the main chamber for the purpose of (2) The fuel is injected from an injection nozzle having a plurality of ports, one of the plurality of ports is directed toward the orifice, and the other one of the plurality of ports is directed toward the glow plug. A direct injection internal combustion engine according to claim 1. (3) Claims characterized in that, based on the engine temperature, an energizing device is provided that increases the amount of current applied to the glow plug when the temperature is low and reduces the amount of current applied to the glow plug when the temperature is high. Direct injection internal combustion engine according to paragraph 1.