JPH04330324A - Swirl chamber type combustion chamber for diesel engine - Google Patents

Abstract

PURPOSE:To reduce a throttle loss of an injection port by the use of a main injection portion and a pair of sub injection portions while sufficiently enhancing air-fuel mixing performance in a swirl chamber and a main combustion chamber. CONSTITUTION:A main vent groove 23 and a pair of sub vent grooves 24. 24 are formed in the end surface 14 of a main combustion chamber for a cylinder head 1. The main vent groove is connected to a main injection portion 13, and it is formed thinner as it is apart from a main injection port. A pair of edge lines 25, 25 between the grooves are formed between the main vent groove and the paired sub vent grooves. The edge lines between the grooves are continuous to edge lines 15, 15 inside the injection port. A main air introducing groove, a pair of sub air introducing grooves and a pair of edge lines between the air introducing grooves are formed on the upper surface of a piston head in facing to the vent grooves and the edge lines formed on the end surface of a main combustion chamber of the cylinder head. The air introducing grooves are formed thinner as they are apart from the main injection portion and sub injection portions.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a whirlpool combustion chamber for a diesel engine.

0002

2. Description of the Related Art Conventionally, a swirl chamber type combustion chamber for a diesel engine has been disclosed, for example, in Japanese Patent Publication No. 57-59410, which was proposed by the present applicant. The basic structure of this diesel engine's spiral combustion chamber is shown in Figure 1.
0 to 12. Here, Figure 1
0 is a longitudinal sectional side view of a main part of the whirlpool type combustion chamber, FIG. 11 is an end view of the cylinder head inside the main combustion chamber, and FIG. 12 is an explanatory view of the function of the whirlpool chamber.

In this whirlpool type combustion chamber, a whirlpool chamber 18 communicates with the main combustion chamber 11 of the diesel engine through a nozzle 12, and the nozzle 12 has a pair of left and right side nozzles on each side of the main nozzle part 13. The lateral sides of the parts 14 and 14 are connected to each other, and the axes Z and Z of the side nozzle parts 14 and 14 extend from the main combustion chamber 11 side to the whirlpool chamber 18 side with respect to the axis X of the main nozzle part 13. The main nozzle part 13 and each side nozzle part 14 are made to incline toward each other as they move closer to each other, and each nozzle internal ridge line 15 is made to run vertically along each communication wall surface portion at a place where the main nozzle part 13 and each side nozzle part 14 communicate with each other. There is.

[0004] According to this configuration, the air-fuel mixing performance in the whirlpool chamber can be improved. That is, first, when the air in the main combustion chamber 11 is compressed in the compression process and passes through the nozzle 12, as shown in FIG.
A minute eddy flow f is generated at the part where it comes into contact with. Next, at the place where the air enters the whirlpool chamber 18 from the nozzle 12, the main jet F1 that has passed through the main nozzle 13 is joined to each side nozzle 14 and 1.
The side jets F2 and F2 that passed through 4 collide from left and right,
There, while stirring and mixing vigorously, they separate and spread to the left and right. Moreover, at this time, the minute eddy flow f is also caught up in the stirring and mixing and diffused. This improves the mixing performance of air and fuel within the swirl chamber 18.

[0005]

[Problems to be Solved by the Invention] The above conventional example is excellent in that the air-fuel mixing performance in the swirl chamber 18 is high as described above, but in order to further enhance this mixing performance, it is necessary to It needs to be long enough. This is because the longer the nozzle 12 is, the more minute eddy flow f is generated due to contact with the inner ridge lines 15 and 15 of each nozzle, and the main jet F1 and side jet F
This is because the ability to travel straight with 2/F2 increases, increasing the power of collision and separation. However, if the nozzle 12 is lengthened, the following disadvantages arise. stomach. During high-speed operation, when the combustion airflow flows from the swirl chamber 18 into the main combustion chamber 11, throttling loss increases and the output decreases. B. During starting operation, air flows from the main combustion chamber 11 to the whirlpool chamber 18.
When flowing inward, a large amount of compression heat escapes from the inner wall surface of the long nozzle 12, resulting in a decrease in engine cold starting performance. The present invention has been made in consideration of these circumstances, and its technical objective is to eliminate the above-mentioned negative effects while maintaining sufficiently high air-fuel mixture performance.

[0006]

[Means for Solving the Problems] The present invention is constructed as follows to solve the above problems. An explanation will be given below using FIGS. 1 to 5, which correspond to embodiments. That is, claim 1
In the invention, in a spiral combustion chamber of a diesel engine having the same basic structure as the conventional example, a main combustion chamber end face 1A facing the main combustion chamber 11 of the cylinder head 1 is provided with a main ventilation groove 23 and a pair of left and right side ventilations. The main ventilation groove 23 is formed so as to extend continuously from the main nozzle part 13 and become gradually shallower as it moves away from the main nozzle part 13. Each of the side ventilation grooves 24 and 24 respectively corresponds to the pair of left and right side nozzle ports 1.
The main ventilation groove 23 and the pair of left and right side ventilation grooves located on the left and right sides of the main ventilation groove 23 are formed so as to extend continuously from the side nozzle holes 14 and 14 and become gradually shallower as they move away from the side nozzle openings 14 and 14. 24, 24, a pair of left and right groove ridge lines 25, 25 are formed between each groove ridge line 25, 24.
25 is characterized in that it is constructed so as to be continuous with the ridge lines 15 within the nozzle openings, respectively.

[0007]The invention according to claim 2 is such that in the swirl chamber type combustion chamber according to claim 1, a main air groove 33 and a pair of left and right side air guide grooves 34 are formed in the piston head 4A, and the main air The groove 33 faces the main nozzle part 13 and the main ventilation groove 23, and is formed to become gradually shallower as it moves away from the main nozzle part 13. The side spout portion 14 respectively
14 and the side ventilation grooves 24, 24, and are formed in a shape that becomes gradually shallower as it moves away from the side nozzle holes 14, 14, and the left and right air grooves located on the left and right sides of the main air groove 33, A pair of side air guide grooves 34.3
4, a pair of left and right ridgelines 35, 35 between the air guide grooves are formed, and the ridge lines 35, 35 between the air guide grooves are configured to face the ridge lines 25, 25 between the grooves, respectively. This is a characteristic feature.

[0008]

[Operation] As shown in FIGS. 7 and 8, the present invention operates as follows. In the invention of claim 1, the main combustion chamber 11
The air inside is compressed in the compression process and flows from the main ventilation groove 23 and each side ventilation groove 24, 24, through the main nozzle part 13 and each side nozzle part 14, 14, to the swirl chamber 18. First, this air generates a large amount of minute eddy flow both in the portions where it contacts the respective inter-groove ridge lines 25 and the portions where it contacts with the respective nozzle internal ridge lines 15 and 15.

Next, the main jet flow F1 passing through the main nozzle part 13
As it runs up inside the main ventilation groove 23, the momentum becomes stronger. The side jets F2 and F2 passing through the side jet ports 14 and 14 also run up inside the side jet ports 14 and 14, so that their momentum becomes strong. As a result, within the swirl chamber 18, the collision force between the main jet F1 and each of the side jets F2 and F2 increases, and the agitation and mixing due to this collision is enhanced, and the separation and diffusion to the left and right due to their separation is also promoted. .

As a result, the mixing performance of air and fuel within the swirl chamber 18 is further enhanced. This enhanced mixing performance eliminates the need to increase the length of the nozzle 12. This reduces the throttling loss of the nozzle 12 and improves the output. Moreover, when starting the engine, the amount of compression heat of the air escaping from the surface within the nozzle 12 is reduced, and cold starting performance is also improved.

[0011] In the invention of claim 2, in the compression step,
The main air groove 33 and the side air grooves 34, 34, and the ridge lines 35, 35 between the air grooves are connected to the main air groove 23, the side air grooves 24,
・It forms a pair with 24 and each groove ridge line 25, 25, and promotes the above action even more strongly. As a result, the performance of mixing air and fuel within the swirl chamber 18 is further enhanced, and the cold start performance is further improved.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in more detail below with reference to the drawings. Fig. 1 is a plan view of the end face of the main combustion chamber of a cylinder head showing the configuration of the whirlpool type combustion chamber according to the present invention, Fig. 2 is a longitudinal cross-sectional side view of main parts showing the configuration of the whirlpool type combustion chamber, and Fig. 3 is a diagram. 2, FIG. 4 is a sectional view taken along line B-B in FIG. 1, FIG. 5 is a plan view of the piston head, and FIG. 6 is taken along line C-C in FIG. 1. FIG. 9 is a cross-sectional view in the direction of arrows, and is a schematic fragmentary view of the main parts of a diesel engine in which the swirl chamber type combustion chamber according to the present invention is employed. In addition, the symbol E in FIG. 9 is a diesel engine, 1 is a cylinder head, 2 is a cylinder block, 3 is a cylinder, 4 is a piston, 7 is an exhaust valve, 8 is a swirl chamber mouthpiece, and 10 is a swirl chamber type combustion of the present invention. Showing the entire room.

This swirl chamber type combustion chamber 10 is connected to a main combustion chamber 11 of a diesel engine E through a nozzle 12 to a swirl chamber 18.
It is configured by communicating. As shown in FIG. 9, the main combustion chamber 11 is formed by forming a cylinder 3 in the center of a cylinder block 2, and fitting a piston 4 into the cylinder 3 so as to be vertically slidable. The whirlpool chamber 18 includes a whirlpool upper hemisphere part 18a recessed in the wall of the cylinder head 1, and a whirlpool lower hemisphere part 18b formed in a half-split whirlpool mouthpiece 8 fitted from the lower open end of the whirlpool chamber upper hemisphere part 18a. It is formed by.

The injection port 5a of the fuel injection nozzle 5 faces the upper hemisphere 18a of the swirl chamber 18, and is configured to inject fuel. The nozzle 12 is formed by connecting the left and right side surfaces of the main nozzle 13 with the lateral sides of a pair of left and right side nozzles 14, 14 so as to moisten as shown in FIGS. 1 to 3.
The axes Z and Z of both side nozzle ports 14, 14 are inclined in a direction approaching the axis X of the main nozzle port 13 from the main combustion chamber 11 side to the whirlpool chamber 18 side. 13 and each of the side nozzle portions 14, 14 are configured such that each nozzle internal ridgeline 15, 15 runs longitudinally along each communication wall surface portion at a location where the nozzle nozzle 13 communicates with each side nozzle portion 14, 14.

The characteristic structure of the present invention will be explained below. In the present invention, the conventional nozzle 12 is improved as follows. That is, as shown in FIGS. 1, 2, and 4, a main ventilation groove 23 and a pair of left and right side ventilation grooves 24 are provided on the main combustion chamber end surface 1A facing the main combustion chamber 11 of the cylinder head 1.
to form. This main ventilation groove 23 is connected to the main nozzle part 13.
It is formed in a shape that extends continuously from the main nozzle part 13 and gradually becomes shallower and widens in a tapered shape as it goes away from the main nozzle part 13. The left and right pair of side ventilation grooves 24, 24 are
They extend continuously from the pair of left and right side nozzle ports 14, 14, respectively, and are formed in a shape that gradually becomes shallower and widens in a tapered shape as it moves away from the side nozzle ports 14, 14. Further, between the main ventilation groove 23 and the pair of left and right side ventilation grooves 24, there are a pair of left and right groove ridge lines 25, 2.
5, and these inter-groove ridgelines 25, 25 are respectively continuous with the respective nozzle inner ridgelines 15, 15. In addition, the reference numeral 6 in FIG. 1 is an intake valve, 26 is an intake port, and 27 is an exhaust port.

According to the above configuration, as shown in FIGS. 7 and 8, compressed air flows from the main ventilation groove 23 and the pair of left and right side ventilation grooves 24, 24 to the main nozzle part 13 and each side nozzle part 14, as shown in FIGS.・Flows to the whirlpool chamber 18 via 14. First, this air generates a large amount of minute eddy flow both in the portions where it contacts the respective inter-groove ridge lines 25 and the portions where it contacts with the respective nozzle internal ridge lines 15 and 15. Next, the main jet flow F1 passing through the main nozzle part 13 runs up inside the main ventilation groove 23 and becomes stronger. Each side jet flow F2 passing through the other side jet port 14.
F2 also runs up inside each side nozzle part 14, 14, and its momentum becomes stronger. Air jet F2 flowing through the left and right side nozzles 14 and 14
・As shown in FIGS. 7 and 8, F2 intersects below the air jet F1 that has passed through the main nozzle 13, and
8, the collision force between the main jet F1 and each of the side jets F2 and F2 increases, and this collision promotes agitation and mixing, and their separation also promotes separation and diffusion to the left and right. This enhanced mixing performance eliminates the need to increase the length of the nozzle 12.
The throttling loss of the nozzle 12 is reduced, and the output is improved. Moreover, when starting the engine, the amount of compression heat of the air escaping from the surface within the nozzle 12 is reduced, and cold starting performance is also improved.

On the other hand, as shown in FIGS. 1 and 5 to 6, the piston head 4A includes the main nozzle port 13 and the main air groove 23 formed on the end surface 1A of the main combustion chamber of the cylinder head 1, as well as the main air grooves 23 and Nozzle part 14, 14 and each side ventilation groove 24, 24
, the main air groove 33, the left and right pair of side air grooves 34, 34, and the ridge lines 35, 35 between the air guide grooves are arranged so as to face the inner ridge lines 15, 15 of the nozzle and the ridge lines 25, 25 between the grooves, respectively. They are formed facing each other.

That is, the main air groove 33 is formed so as to face the main air nozzle part 13 and the main air groove 23, and is gradually shallower and wider in a tapered shape as it moves away from the main nozzle part 13. The pair of left and right side air guide grooves 34 are made to face the side nozzle holes 14 and the side ventilation grooves 24 and 24, respectively, and are gradually shallower as they move away from the side nozzle holes 14 and 14. , and form it into an expanding shape. A pair of left and right air guide groove ridge lines 35 are formed between the main air groove 33 and a pair of side air guide grooves 34 located on both sides. The air-conducting groove-to-groove ridgelines 35 are formed to face the groove-to-groove ridgelines 25, 25, respectively. In FIGS. 1 and 3, reference numeral 26a indicates an intake valve recess, and 27a indicates an exhaust valve recess, and the main air groove 33 and the pair of left and right side air guide grooves 34, 34 are connected to the intake and exhaust valve recesses 26a, 27a, respectively. Some rap.

According to the above structure, in the compression process, the main ventilation groove 23, each of the side ventilation grooves 24, 24, the main ventilation groove 23
, are paired with each side ventilation groove 24, 24, and the main jet flow F
1. Promote the run-up of each side jet F2 even more powerfully. As a result, the performance of mixing air and fuel within the swirl chamber 18 is further enhanced, and the cold start performance is further improved. On the other hand, the nozzle 12 is opened toward the intake/exhaust valve recesses 26a and 27a formed in the piston head 4A, and is in a condition to guide the combustion airflow, so that when the combustion airflow flows into the main combustion chamber 11, it is properly controlled. Dispersion increases combustion efficiency.

[0020]

Effects of the Invention Since the present invention is constructed and operates as described above, it has the following effects. stomach. Even if the distance of the nozzle 12 between the main combustion chamber 11 and the whirlpool chamber 18 is short, three powerful air jets are generated to improve the mixing performance of air and fuel. B. Furthermore, since the distance between the main combustion chamber 11 and the whirl chamber 18 between the nozzle 12 is short, the throttling loss of the nozzle 12 during high-speed operation is reduced and the output is increased. C. Furthermore, since the distance between the nozzle holes 12 is short, it is possible to prevent compression heat from escaping at the time of starting, thereby improving cold starting performance. D. In particular, in the invention of claim 2, the main air groove 33 formed in the piston head 4A, the pair of left and right side air guide grooves 34, 34, and the ridge lines 35, 35 between the respective air guide grooves are formed on the main combustion chamber end surface 1A of the cylinder head 1. Since the main ventilation groove 23, each of the side ventilation grooves 24, 24, the main ventilation groove 23, each of the side ventilation grooves 24, 24, etc. formed work together to generate three powerful air jets,
The mixing performance of air and fuel is further enhanced, and on the other hand, when the combustion airflow flows into the main combustion chamber 11, the dispersion performance of the combustion airflow is improved due to the above-mentioned reverse effect, thereby further increasing the combustion efficiency. .

[Brief explanation of the drawing]

FIG. 1 is a plan view of an end surface of a main combustion chamber of a cylinder head showing the configuration of a swirl chamber type combustion chamber according to the present invention.

FIG. 2 is a longitudinal cross-sectional view of essential parts showing the configuration of the swirl chamber type combustion chamber according to the present invention.

FIG. 3 is a sectional view taken along line A-A of the nozzle in FIG. 2;

FIG. 4 is a sectional view taken along line BB in FIG. 1;

FIG. 5 is a plan view of the piston head.

6 is a sectional view taken along the line CC in FIG. 2; FIG.

FIG. 7 is an explanatory diagram of the operation of the present invention.

FIG. 8 is an explanatory diagram of the operation of the present invention.

FIG. 9 is a schematic cutaway view of essential parts of a diesel engine employing the swirl chamber type combustion chamber according to the present invention.

FIG. 10 is a vertical cross-sectional view of essential parts showing the configuration of a conventional swirl chamber type combustion chamber.

FIG. 11 is a diagram corresponding to FIG. 1 of a conventional example.

FIG. 12 is an explanatory diagram of the operation of a conventional example.

[Explanation of symbols]

E...Diesel engine, 1
... Cylinder head, 1A... Main combustion chamber end face of cylinder head, 4A... Piston head, 11... Main combustion chamber,
12... Nozzle port, 13... Main nozzle part,
X... Axis center of main nozzle part, 14... Side nozzle part,
Z...axis of side nozzle, 15...nozzle inner ridgeline,
18... vortex chamber, 23... main ventilation chamber,
24... Side ventilation chamber, 25... Groove ridgeline,
33...Main air groove, 34...Side air groove,
35...Ridge line between air conduction grooves.

Claims (2)

[Claims] [Claim 1] Main combustion chamber (1
1) is communicated with the swirl chamber (18) through the nozzle (12), and the nozzle (12) has a pair of left and right side nozzles (14) on each left and right side of the main nozzle (13). The axial center (Z) of both side nozzle portions (14) (14)
(Z) is inclined in a direction approaching the axis (X) of the main nozzle part (13) as it progresses from the main combustion chamber (11) side to the whirlpool chamber (18) side. Each side spout (
14) In a diesel engine whirlpool-type combustion chamber configured by vertically running each nozzle internal ridgeline (15) (15) along each communication wall surface portion of the part where the (14) communicates with the cylinder head (1). A main ventilation groove (23) and a pair of left and right side ventilation grooves (24) (24) are formed in the main combustion chamber end face (1A) facing the main combustion chamber (11), and the main ventilation groove (23)
are formed so as to extend continuously from the main nozzle part (13) and become gradually shallower as they move away from the main nozzle part (13), and each of the pair of left and right side ventilation grooves (
24) (24) respectively represent the pair of left and right side nozzle ports (
14) It extends continuously from (14), and is formed in a shape that becomes gradually shallower as it goes away from the side nozzle part (14) (14), and is located on the left and right sides of the main ventilation groove (23). The above pair of left and right side ventilation grooves (24) (2)
A pair of left and right groove ridge lines (25) (25) are formed between the grooves 4), and the groove ridge lines (25) (25) are connected to the respective nozzle inner ridge lines (15) (15), respectively. A swirl chamber type combustion chamber for a diesel engine is characterized by being configured. [Claim 2] A leading air groove (
33) and a pair of left and right side air guide grooves (34), the main air grooves (33) facing the main nozzle part (13) and the main ventilation groove (23), Formed in a shape that gradually becomes shallower as it moves away from the main nozzle part (13), each of the pair of left and right side air guide grooves (34) (34)
are formed to face the side nozzle portions (14) (14) and the side ventilation grooves (24) (24), respectively, and to become gradually shallower as they move away from the side nozzle portions (14) (14). The main air groove (33) and the pair of left and right side air grooves (34) located on both sides of the main air groove (33).
(34) and the left and right pair of air conduction groove ridge lines (35) (
35), and the ridge lines (35) (35) between the respective air conduction grooves
The whirlpool combustion chamber for a diesel engine according to claim 1, wherein said groove ridge lines (25) and (25) are opposed to each other.