JP2518408Y2 - Diesel engine combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a combustion device for a diesel engine.

[Conventional technology]

FIG. 3 is a sectional view of a conventional single injection side injection type diesel engine. In the figure 01
Is a cylinder head, 02 is a cylinder liner, 03 is a piston, 04 is a combustion chamber, 05 is a fuel valve, 06 is fuel spray, 07 is a gap between the piston and the cylinder head, and Sw is an air swirl. FIG. 4 is a relationship diagram of a cylinder, a combustion chamber, and an intake / exhaust valve, 02 is a cylinder liner, 03 is a piston, 04 is a combustion chamber, 05 is a fuel valve, 09 is an intake valve, 010 is an exhaust valve, and D _S is The fuel injection direction, Sw, indicates an air swirl. FIG. 5 is an explanatory view showing the movement direction of the fuel spray.

In the diesel engine having the above structure, when the piston 03 moves up and approaches the vicinity of the top dead center, fuel is injected from the fuel valve 05 and the fuel spray 06 is formed. At this time, considering that there is only one spray from the fuel valve 05, a strong air swirl Sw is generated during the air supply stroke in order to promote the mixing of fuel and air. In the combustion chamber 04, the fuel spray is spread as much as possible to increase the contact area with the air and to form the air-fuel mixture with a spherical surface. Usually, the injection direction is set in order to obtain such an effect, that is, the use of a strong swirl and the wide dispersion of the fuel on the wall surface of the combustion chamber, so that good combustion can be obtained. As shown in the figure, the position of the fuel valve is determined in relation to the intake / exhaust valve position of the cylinder head, and the combustion chamber is determined from the position of the fuel valve. It is set.

[Problems to be solved by the device]

However, in the conventional combustion chamber shape, the injected fuel collides with the combustion chamber wall surface, spreads, and develops while being swept by the air swirl. At this time, it is intended to swirl the spray horizontally into the combustion chamber by the strong air swirl so that the air in the combustion chamber is fully utilized. However, in the actual device, it is necessary to supply the fuel within a predetermined period, so the injection port area of the fuel valve cannot be reduced in order to make the atomization fine,
Therefore, the penetration force of the spray is too strong relative to the air swirl. Therefore, the fuel spray is not swirled in the horizontal direction sufficiently by the air swirl after it collides with the wall surface, and is maintained in the direction of motion by being controlled by the wall surface. As shown in FIG. 5, it flows out of the fuel chamber. The spray that has flowed out of the combustion chamber enters the gap 07 between the cylinder head 01 and the piston 03 shown in FIG. 3, obstructing the introduction of air and preventing sufficient combustion.

As described above, in the conventional apparatus, the amount of air introduced into the spray before and after the collision of the spray with the combustion chamber is small and insufficient, and the air stored in the combustion chamber cannot be fully utilized, resulting in an air utilization rate It lowers the combustion efficiency and causes the exhaust concentration to increase.

[Means for solving the problem]

A combustion chamber of a diesel engine according to the present invention has a piston having a substantially spherical combustion chamber, a cylinder head located near the outer periphery of the combustion chamber, a nozzle, and a fuel for forming a spray. In a direct-injection diesel engine equipped with a valve; among the straight lines connecting the cylinder center O and the combustion chamber center P in the combustion chamber, the geometric fuel is arranged on a straight line portion opposite to the cylinder center O with respect to the combustion chamber center P. It is characterized in that the injection directions D _S are orthogonal to each other.

[Action]

The strong swirl formed on the eccentric direction side of the combustion chamber center with respect to the cylinder center enhances the introduction of air into the spray in the space up to the wall collision, promotes the mixing of fuel and air, and suppresses the penetration force of the spray. The spray movement after collision is changed in the direction of swirl in the combustion chamber to improve the air utilization rate and achieve good combustion.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a plan view of a combustion apparatus according to the present invention, and FIG.
The drawing is a plan view showing the air flow velocity in the cylinder when the combustion chamber is provided eccentrically with respect to the center of the cylinder.
In FIG. 1, the combustion chamber 4 is eccentrically installed on the upper surface of the piston 03. In this embodiment, of the straight line connecting the center O of the cylinder and the center P of the combustion chamber, the straight line portion on the opposite side from the center O of the cylinder with respect to the center P of the combustion chamber is arranged so that the geometric injection direction D _S is orthogonal to the fuel valve. The fuel injection direction D _S of 05 is determined. The shaded area of A indicates the area where the air velocity in the combustion chamber is high, and Sw indicates the swirl direction in the cylinder.
Further, in FIG. 2, 03 is a piston, 04 is a combustion chamber, an arrow shown by a broken line 11 is an air swirling flow component between the piston top surface and the cylinder head, an arrow shown by a solid line 12 is a swirling flow component in the combustion chamber, and Sw is Shows the swirl direction in the cylinder.

 Next, the operation of the above embodiment will be described.

In a direct-injection diesel engine, the swirling flow of air called swirl in the cylinder due to the intake port during the normal intake stroke.
Although the Sw is formed, as the piston rises and enters the compression stroke, the air between the top surface of the piston and the cylinder head is especially compressed at the top dead center where fuel is injected. Since the volume of the outer region becomes small in the vicinity, most of it is pushed out to the combustion chamber side, forming a so-called squish flow having a swirl direction flow velocity component and a combustion chamber direction flow velocity component. However, when the position of the combustion chamber is eccentric or offset with respect to the center of the cylinder, the strength of the squish differs depending on each position on the top surface of the piston, and the squish flow also affects the swirl flow in the combustion chamber. As a result, the swirl velocity in the combustion chamber also has a strong or weak distribution. FIG. 2 is a plan view showing the above situation. When the center O of the cylinder and the center P of the combustion chamber are eccentric as shown in the figure, the volume change is large on the piston top surface opposite to the eccentric direction. The flow velocity increases, and conversely, the squish flow velocity decreases at the eccentric piston top surface. This situation is shown by the dashed arrow 11. On the other hand, the swirl flow velocity in the combustion chamber is greatly affected by the squish flow velocity at the opposite position, and the swirl flow velocity in the vicinity of the inner peripheral combustion chamber wall surface A in the eccentric direction becomes stronger due to the influence of the squish flow on the side opposite to the eccentric direction, and conversely. The flow velocity near the wall surface in the anti-eccentric direction becomes weak due to the influence of the squish flow on the eccentric direction side. This situation is shown by 12 solid arrows. In the conventional combustion chamber, as shown in FIG. 4, the injection direction D _S in the combustion chamber is set by determining the arrangement of the fuel valve 05 by the positions of the intake and exhaust valves 09,010 of the cylinder head, and then the position of the combustion chamber. However, it is not always the case that the air flow in the combustion chamber is used effectively, and in some cases the spray is mainly developed in a region where the air flow is weak. It was

On the other hand, in the present invention, an attempt is made to utilize the air flow velocity distribution formation state in the combustion chamber, and as shown in FIG. 1, the geometric injection direction is set to the cylinder center O and the combustion chamber center P.
Of the straight line passing through the center of the cylinder opposite to the center of the combustion chamber so that the fuel spray is developed in the region A where the swirling flow velocity in the vicinity of the inner wall on the eccentric direction side of the combustion chamber in the combustion chamber 04 is relatively large. In this configuration, the strong swirling flow in the region A promotes the introduction of air into the spray, suppresses the penetration force of the spray, and sufficiently swirls the spray after it collides with the wall surface of the combustion chamber to complete the swirling. It is designed to prevent combustion from flowing out of the combustion chamber all at once.

[Effect of device]

The combustion chamber of the diesel engine according to the present invention is configured as described above, and the strong swirl flow formed in the region A of the combustion chamber by the combustion chamber offset is used to promote the introduction of air into the spray and to enhance the penetration force of the spray. The feature is that the spray is prevented from flowing out of the combustion chamber at once, the air utilization rate is increased to increase the combustion efficiency, and the exhaust concentration is low and the noise is low and good combustion can be obtained. .

[Brief description of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a plan view of the structure, and FIG. 2 is a plan view showing a swirling flow in a cylinder when a combustion chamber is offset. FIGS. 3 to 5 are conventional examples, FIG. 3 is a sectional view showing the configuration of a single injection hole side injection combustion system, FIG. 4 is a correspondence diagram of FIG. 1, and FIG. 5 is a perspective view showing a moving direction of spray. . 03 …… Piston, 04 …… Combustion chamber, A …… A large swirl flow area in the combustion chamber, O …… Cylinder center, P …… Combustion chamber center, D _S …… Geometric injection direction, Sw …… Swirl .

Claims (1)

(57) [Scope of utility model registration request] 1. A fuel having a substantially spherical combustion chamber in a piston (03), a cylinder head having one nozzle located near the outer periphery of the combustion chamber, and forming one spray. In a direct injection diesel engine equipped with a valve (05), the geometrical injection direction (Ds) from the fuel valve (05) is set in the combustion chamber at the cylinder center (O) and the combustion chamber center (P).
A combustion device for a diesel engine, characterized in that it is formed so as to be orthogonal to a straight line portion on the side opposite to the center (O) of the cylinder with respect to the center (P) of the combustion chamber, among the straight lines that connect with.