JPS5985424A - Diesel engine of direct injection type - Google Patents

Abstract

PURPOSE:To compact the construction of a Diesel engine with its rate of fuel consumption improved by locating the jet hole of the fuel injection nozzle in the neighborhood of the periphery of a dint of the top combustion chamber situated at the upper dead point and by setting the major stream in injection in an angle of 20-30 deg. to the top surface of the piston. CONSTITUTION:A recess 6 is provided in a part of periphery of a dint 5 of the combustion chamber of a piston 4, and a setting is made so that a jet hole 8 of a fuel injection nozzle 7 furnished at the cylinder head 2 is situated at this recess 6 at the time of upper dead point and that the angle alpha formed by the major stream in fuel injection from this jet hole 8 with respect to the top surface of the piston 4 will be 20-30 deg.. This setting of injection angle to 20-30 deg. will prolong the reach of atomized fuel sufficiently, which should enhance the rate of fuel consumption as well as reduce the density of black smoke in the exhaust gas. Thus a sufficient reach can be obtained without a larger compression height of piston, that ensures a compacted construction of Diesel engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a direct injection diesel engine, and particularly to a single spray type direct injection diesel engine used in vehicles such as automobiles.

A direct 11ft DJ type diesel engine generally has a fuel injection nozzle attached to the cylinder head, and directs diesel engine liquid fuel such as light oil from the nuclear fuel injection nozzle into the combustion chamber recess provided at the top of the piston. It is supplied by injection.

In this type of direct injection type deep-pil engine, the atomization of the fuel in the combustion chamber cavity and the mixing state of the fuel and air have a large effect on the combustion speed and combustion efficiency, and generally the fuel is injected into the combustion chamber. It is preferable that the distance from when the fuel is injected from the nozzle to when it reaches the wall surface of the recess in the combustion chamber, the so-called spray arrival distance, is long in order to improve the atomization of the fuel 1 and the mixing state of the fuel and air. Immediately after being injected from the fuel injection nozzle, the fuel is in a liquid column state, and in order to form a spray, a minimum spray reach is required. By enlarging the recess of the combustion chamber with screws 1 to 1 and moving the wall surface of the recess of the combustion chamber facing the nozzle of the fuel injection nozzle further away from the fuel injection nozzle, it is possible to reduce the reach distance of the spray. However, in conventional direct injection diesel engines, fuel injection is performed so that the main stream of fuel injected from the fuel injection nozzle has a relatively large J angle with respect to the top surface of the piston. 0
4 nozzles are attached to the cylinder head, and the fuel injection nozzle directs the fuel toward the bottom of the recess in the combustion chamber. Therefore, in order to increase the spray reach distance, it is necessary to As a result, the combined height of the piston increases, increasing the overall height of the engine and making it difficult to mount it on a vehicle.

An object of the present invention is to provide a direct injection diesel engine that is compact and has good fuel efficiency and exhaust gas performance, which can provide a sufficient spray distance without significantly increasing the piston combination height. .

According to the present invention, the jet nozzle is located near the periphery of the combustion furnace recess at the top of the piston at the top dead center, and once the main flow of fuel injected from the jet nozzle is 20 degrees to the top of the piston. This is accomplished by a direct injection diesel engine with fuel injection nozzles angled at ~30 degrees.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of example embodiments with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing the main parts of one embodiment of a direct injection diesel engine according to the present invention, and FIG. 2 is a plan view of a piston of the direct injection diesel engine shown in FIG. 1. .

In the figure, 1 is a cylinder block, 2 is a cylinder head installed in the cylinder block 1 to close one end of the cylinder bore 3 of the cylinder block 1, and 4 is a cylinder head installed in the cylinder bore 3. Each piston is shown separately.

The piston 4 has a combustion chamber recess 5 at its top. The combustion chamber recess 5 is relatively shallow and has a nearly elliptical cross-sectional shape in the piston axial direction and a circular piston radial cross-sectional shape. In small direct injection type diesel engines with a piston bore 3 diameter of 10011I111 or less, the diameter of the combustion chamber recess 5 is generally as follows:
It is about 0.37-(1.43D. If the opening diameter of the combustion chamber recess 5 is (1), the depth of the combustion chamber recess is Oo:
)・-0,7 (may be about 1).

A recess 6 is provided in a part of the peripheral edge of the combustion chamber n: groove 5 of the piston 4 in order to expand a part of the combustion chamber recess 5 tangentially outward.
] The cylinder head 2 has a fuel injection nozzle 7
The fuel injection port/nozzle is of a single-injection hole type, and has one injection port 8 at its tip. The fuel injection nozzle 7 is located at the fourth part 6 of the piston 4, where the injection port 8 is at the dead center position, as shown in the figure.
It is attached to the cylinder head 2 so that the main stream of the fuel spray injected from the nozzle 8 makes an angle α of 20 to 30 degrees with respect to the top of the nozzle 4.

The minimum spray reach distance at which a spray can be obtained varies depending on the fuel injection pressure of the fuel injection nozzle, the diameter of the nozzle of the fuel injection nozzle 7, the shape of the nozzle, etc., but is generally (30 to 40 mm).
In a small direct injection diesel engine such as the one shown in the top three (see above), the minimum spray reach is in the combustion chamber recess 5 of the piston TU all with the nozzle 8 at the top and the dead center position. The main flow of fuel injected from the nozzle 8 located near the peripheral edge is 20 to 30 r(
This is obtained by attaching the fuel injection nozzle 7 to the cylinder head 2 so as to form an angle of Jt.

The direction of the fuel spray from the fuel injection nozzle 7, the amount of spray per unit time, and the strength of the vortex generated in the combustion chamber depression 5 are important factors in order to obtain a good air-fuel mixture with small spray particles. Therefore, it is important to properly adjust these factors to 1 at the same time. In order to inject the fuel in the direction along the vortex flow and effectively utilize its energy, the fuel injection nozzle 7 is inserted into the recess of the combustion chamber, as shown by Q in FIG. The fuel is directed into the combustion chamber recess 5 from a position biased to one side from the center of the recess 5 to the nozzle 1'IJ.

FIG. 3 shows the angle α formed by the main stream of fuel H injected from the nozzle with respect to the top surface of the piston, that is, the relationship between the injection angle α and the fuel consumption rate. FIG. 7 shows the relationship between the injection angle α and the black smoke concentration in the exhaust gas. It is clear from these two graphs that if the injection angle α is between 20 and 30 degrees, the fuel efficiency is good and the degree of blackness in the exhaust gas is low, but when the injection angle exceeds 301 α, the fuel efficiency deteriorates. Also, the black smoke angle in the 1-no-1 gas increases.

This is because when the injection angle α exceeds 30 degrees, sufficient spray reach cannot be obtained, the atomization of fuel H and the mixing state of fuel and air deteriorate, and the combustion efficiency and combustion speed deteriorate. It is assumed that this is because

FIGS. 5 and 6 each show the main parts of an embodiment of the direct injection type deep-pillar engine according to the present invention.

In the embodiment shown in FIG. 5, the fuel injection nozzle 7 is of a bottle type. If a bottle-type fuel injection nozzle is used, the fuel injection nozzle 7
It must be mounted at a relatively small angle to the top surface of the piston depending on the injection angle.

In the embodiment shown in FIG. 6, the shape of the combustion chamber recess 5 has been changed.

In any of the embodiments, by attaching the fuel injection nozzle to the cylinder head so that the injection angle is between 20 and 30 degrees, the minimum required spray travel distance can be obtained.

Although the present invention has been described in detail above with reference to specific embodiments, it is understood by those skilled in the art that the present invention is not limited to these and that various embodiments are possible within the scope of the present invention. It would be obvious for

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing essential parts of an embodiment of a direct injection diesel engine according to the present invention, FIG. 2 is a plan view of a piston of the direct injection diesel engine shown in FIG. 1, and FIG. Figure 3 is a graph showing the relationship between injection angle and fuel consumption rate, Figure 4 is a J graph showing the relationship between injection angle and black smoke concentration in exhaust gas, and Figures 5 and 6 are each according to the present invention. FIG. 3 is a longitudinal cross-sectional view showing the main parts of another embodiment of the direct injection diesel engine. 1...Cylinder block, 2...Cylinder head. 3... Cylinder bore, 4... Piston, 5... Combustion chamber recess, 6... Recess, 7... Fuel injection nozzle, 8
・・・Nozzle property Applicant: Toyota Motor Corporation representative Patent attorney: Meiyi Chang Yi Figure 1 Figure 2 Figure 3 Figure 4 Injection angle; α (deg) (Voluntary) Procedural amendment 1982 May 25, 2015 Kazuo Wakasugi, Commissioner of the Japan Patent Office1, Indication of the case: Showa 571 [Patent Application No. 19627 April 2, Name of the invention: Direct injection diesel engine 3, Relationship with the amended person's case: Patent applicant's address 1 Toyota-cho, Toyota City, Aichi Prefecture Name (3)
20) Toyota Jidosha Co., Ltd. 4, agent address: 3rd floor, Kayabacho Nagaoka Building, 1-5-19 Shinkawa, Chuo-ku, Tokyo 104 Tel: 551-4176, J for amendments
:Increase in the number of covered inventions 0 (1) The scope of claims is amended as follows. A direct injection diesel engine having a fuel injection nozzle whose nozzle is at an angle of 20 to 30 degrees with respect to the perforation surface of the combustion chamber at the top of the piston at top dead center. j (2) Mei ll book 3
Add "1 main flow is at top dead center between piston J" and "R top dead center" on the 10th line of the page. (3) Correct the lines 2 and 12 of page 5 to read, ``The piston 4 with the nozzle 4J at its dead center position, respectively.''<4) Add ``located at top dead center'' between ``mainstream flow'' and ``piston'' on page 6, lines 7 to 8.

Claims (1)

[Claims] A fuel injection nozzle in which the injection port is located near the periphery of the recess of the combustion chamber at the top at the top dead center, and the main stream of fuel injected from the injection port forms an angle of 20 to 30 degrees with respect to the top surface of the piston. A direct injection diesel engine.