JPH0558838U - Combustion chamber of swirl chamber type diesel engine - Google Patents

Abstract

(57) [Abstract] [Purpose] In the swirl chamber 8, the fuel spray always advances in a portion where the flow of the swirling flow is strong, and the ignition delay period is shortened. [Structure] The swirl chamber 8 on the cylinder head 2 side has a substantially cylindrical shape whose center axis is parallel to the cylinder center axis. The injection port 9 opening to the outer peripheral portion of the bottom surface is formed along the tangential direction of the cylinder of the swirl chamber 8 in order to generate a swirling flow in the lateral direction. The fuel injection nozzle 10 is arranged so as to inject fuel along the outer peripheral portion of the swirl chamber 8 from above to below, and is located above the opening of the injection port 9.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a combustion chamber of a swirl chamber type diesel engine, and more particularly to improvement of a swirl chamber portion.

[0002]

[Prior Art]

 A swirl chamber type diesel engine generally has a substantially spherical swirl chamber, and the air forced through the nozzles during the compression stroke produces a strong swirling flow in the longitudinal direction, that is, substantially along the plane including the cylinder center axis. It has become so. The injection direction of the fuel injection nozzle arranged above the swirl chamber is usually set so as to follow the forward direction of the swirl flow. In such a swirl chamber type diesel engine, the fuel injected from the fuel injection nozzle rides on the swirling flow in the swirl chamber, mixes with air, and ignites and burns. Then, combustion gas containing unburned fuel is ejected from the swirl chamber to the main combustion chamber side through the injection port, and diffusion combustion is completed in the main combustion chamber (see, for example, JP-A-63-23388). ).

[0003]

[Problems to be solved by the device]

 In the above swirl chamber, the swirl flow strongly flows in the outer peripheral part of the swirl chamber and is weak in the central part. Therefore, although the fuel injected from above into the swirl chamber is partially diffused by the strong flow in the outer periphery and mixes with the air, when the spray approaches the center of the swirl chamber, it becomes the air due to the swirling flow. The mixing action of is weakened. After that, when the spray reaches the lower part of the swirl chamber, the mixing is strongly promoted again, and the ignition is reached. As described above, in the conventional configuration, since the mist passes near the center of the swirl chamber, there is a period in which the mixing of fuel and air is not promoted so much, and a period of time is wasted until ignition. Therefore, there is a problem that the ignition delay period cannot be shortened to a certain extent or more, it is difficult to sufficiently reduce the idle noise, and the HC and smoke emissions are large.

[0004]

In a combustion chamber of a swirl chamber type diesel engine according to the present invention, a substantially cylindrical swirl chamber having a central axis parallel to the cylinder central axis is formed on the cylinder head side, and the swirl A jet port is formed from the outer peripheral part of the bottom surface of the chamber to the main combustion chamber along the tangential direction of the substantially cylindrical swirl chamber, and at the outer peripheral part of the upper end of the swirl chamber, substantially parallel to the central axis of the swirl chamber and swirl flow. It is characterized in that a fuel injection nozzle is arranged so as to inject fuel along the outer peripheral portion of the chamber.

[0005]

[Action]

 In the above configuration, since air is pushed into the vortex flow chamber having a substantially cylindrical shape in the compression stroke from the tangential direction through the injection port, a swirling flow is generated along the cylindrical shape. In other words, a lateral swirling flow is generated with the central axis parallel to the cylinder. Then, the fuel is injected along the outer periphery of the swirling flow substantially parallel to the central axis of the swirling flow. Therefore, the spray progresses only in the outer peripheral portion where the flow velocity of the swirling flow is large, the mixing with the air is continuously promoted, and the ignition is accelerated.

[0006]

【Example】

 An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a main part of a swirl chamber type diesel engine according to the present invention, in which 1 is a cylinder block, 2 is a cylinder head, and 3 is a piston. The lower surface of the cylinder head 2 that covers the upper surface of the cylinder 4 is formed as a flat surface, and a main combustion chamber 5 is defined between the cylinder head 2 and the top surface of the piston 3. It should be noted that the top surface of the piston 3 is provided with a cavity 6 having a clover leaf shape, for example.

A hot plug 7 is press-fitted from the lower surface side to a side portion of the cylinder head 2 corresponding to the peripheral portion of the cylinder 4, and a swirl chamber 8 is formed by using the hot plug 7. The swirl chamber 8 has a substantially cylindrical shape whose central axis is parallel to the central axis of the cylinder 4, and the peripheral corner portions at the upper and lower ends are slightly rounded. The swirl chamber 8 communicates with the main combustion chamber 5 through an injection port 9 formed obliquely through the hot plug 7, and the injection port 9 has a substantially circular passage cross section as shown in FIG. The vortex chamber 8 has an opening on the outer peripheral portion of the bottom of the vortex chamber 8 and is formed along the tangential direction of the cylindrical shape of the vortex chamber 8. Further, a fuel injection nozzle 10 having a single injection port is provided on the outer periphery of the upper end of the swirl chamber 8. The fuel injection nozzle 10 is mounted on the cylinder head 2 substantially vertically, and its injection axis F is parallel to the central axis of the swirl chamber 8 and extends along the outer periphery of the swirl chamber 8, as shown in FIG. Is set. Specifically, the fuel injection nozzle 10 is located above the opening in the swirl chamber 8 of the injection port 9, and the injection axis F is oriented near the opening.

A glow plug 11 that heats the inside of the swirl chamber 8 at the time of cold start is attached to the cylinder head 2 from a substantially horizontal direction. The tip of the glow plug 11 is inserted at a height position approximately in the middle of the swirl chamber 8, and in particular, as shown in FIG. 2, the cylinder of the swirl chamber 8 is arranged so as not to hinder the swirling flow. It is located at a position recessed from the surface.

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

When the piston 3 rises in the compression stroke, air is pushed into the cylindrical swirl chamber 8 from the tangential direction through the injection port 9 and proceeds in a spiral shape, so that the swirl chamber 8 is shown in FIG. 2 by an arrow. A swirling flow is generated. That is, a lateral swirling flow having a central axis parallel to the central axis of the cylinder 4 is generated. The fuel spray injected from the fuel injection nozzle 10 at a predetermined time before top dead center advances along the outer peripheral portion of the swirl chamber 8 in parallel with the central axis of the swirling flow. In other words, the injection is performed in the direction orthogonal to the flow direction of the swirl flow, and the flow always proceeds along the outermost part of the swirl flow, which has the strongest flow. Therefore, the fuel spray is continuously subjected to the effect of promoting the mixing with the air by the swirling flow and promptly ignites and burns. That is, the ignition delay period is shortened, idle noise is reduced, and HC is suppressed. Further, since the mixing of the fuel and the air in the swirl chamber 8 becomes good, the generation of smoke is suppressed, and the output can be further increased. Since the fuel spray progresses toward the opening of the injection port 9, the ignited fuel becomes a flame and is ejected from the injection port 9 more quickly, promoting diffusion combustion in the main combustion chamber 5. it can.

Further, in the above configuration, the fuel injection nozzle 10 is mounted on the cylinder head 2 from above, and the glow plug 11 is mounted on the cylinder head 2 from the side. It does not add complexity to the structure.

[0013]

[Effect of the device]

 As is clear from the above description, according to the combustion chamber of the swirl chamber type diesel engine according to the present invention, the swirling flow continuously promotes the mixing promotion action with the air to the fuel spray in the swirl chamber. As a result, the fuel and air are mixed well and the ignition delay period is very short. Therefore, reduction of idle noise and reduction of HC and smoke can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a combustion chamber of a swirl chamber type diesel engine according to the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 5 ... Main combustion chamber 8 ... Vortex chamber 9 ... Injection port 10 ... Fuel injection nozzle

Claims (1)

[Scope of utility model registration request] 1. A substantially cylindrical vortex chamber having a central axis parallel to the central axis of the cylinder is formed on the cylinder head side, and extends from the outer peripheral portion of the bottom surface of the vortex chamber in a substantially tangential direction of the substantially vortex chamber. And a fuel injection nozzle is provided on the outer peripheral portion of the upper end of the swirl chamber so as to inject fuel substantially parallel to the central axis of the swirl chamber and along the outer peripheral portion of the swirl chamber. A combustion chamber of a swirl chamber type diesel engine characterized by the above.