JP2001065352A - Structure of uniflow type two-cycle internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the flowing resistance of an exhaust gas at both exhaust ports by determining a distance between two exhaust valves far from one longitudinal side surface among four exhaust valves mounted on a cylinder head, to be longer than a distance between two exhaust valves near one longitudinal side surface. SOLUTION: Four exhaust valves 9-12 are sorted two by two at left and right sides over a longitudinal axis 17 extending in the crank axial direction through a center 0 of a cylinder 2. Here, a distance L2 between two exhaust valves 11, 12 far from one longitudinal side surface 3a is longer than a distance L1 between two exhaust valves 9, 10 near one longitudinal side surface 13a. Further a distance S2 from two exhaust valves 11, 12 to a longitudinal axis 17 is shorter than a distance S1 from two exhaust valves 11, 12 to the longitudinal axis 17. Further exhaust ports 13-16 respectively extending from the exhaust valves 9-12 are joined to one exhaust port 20, and opened to one longitudinal side surface 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a uniflow type two-stroke internal combustion engine comprising a scavenging port for introducing new air into a cylinder at a lower portion of the cylinder and an exhaust valve provided at a cylinder head at the top of the cylinder. It concerns the structure of the institution.

[0002]

2. Description of the Related Art Generally, in a uniflow type two-stroke internal combustion engine of this type, at the end of a downward movement of a piston due to an explosion stroke, a scavenging port at a lower portion of a cylinder is opened,
When the exhaust valve at the top of the cylinder is opened, scavenging is performed in which exhaust gas in the cylinder is discharged from the exhaust valve through the exhaust port while introducing new air from the scavenging port to the cylinder, and then the piston is lifted. At the end of the compression stroke due to dynamics, fuel is injected and supplied, and then the fuel repeatedly burns and explodes to the explosion stroke.

In this type of uniflow two-stroke internal combustion engine, in order to improve the scavenging efficiency in the cylinder, it is necessary to reduce the resistance of the exhaust gas flowing out of the exhaust valve as much as possible. In addition, a plurality of exhaust valves at the top of the cylinder are used, and Japanese Patent Application Laid-Open No. 6-33830 discloses a prior art.
Four exhaust valves are provided, and the four exhaust valves are respectively left and right with respect to a longitudinal axis extending in the crankshaft direction through the center of the cylinder and an orthogonal axis extending perpendicular to the longitudinal axis through the center of the cylinder in plan view. It is proposed to construct a symmetrical square array.

[0004]

However, the exhaust port formed inside the cylinder head so as to extend from the exhaust valve has its outlet end opened to one of the left and right longitudinal sides of the cylinder head. Thereby, since it is configured to communicate with the exhaust manifold joined to the one longitudinal side surface, when the number of the exhaust valves is four,
The two exhaust ports extending from two exhaust valves far from one longitudinal side of the four exhaust valves have an intermediate portion outside the two exhaust valves avoiding the two exhaust valves near the one longitudinal side of the four exhaust valves. Need to be curved outward in a plan view so as to bypass.

In this case, if the arrangement of the four exhaust valves is square with respect to the crank axis and the orthogonal axis perpendicular thereto, as in the prior art, one of the four exhaust valves has a longitudinal side surface. In the case where the middle part of the two exhaust ports extending from the two exhaust valves far from the outside is curved outward, the outward curved dimension must be increased, in other words, the exhaust ports are outwardly large. Since there is a need to bend and the flow resistance of the exhaust gas increases, there is a problem that the effect of having four exhaust valves is considerably reduced.

In a compression ignition type internal combustion engine,
A glow plug for starting ignition is disposed in a portion between at least two exhaust valves among the four exhaust valves, and the four exhaust valves are arranged in a symmetrical square arrangement with respect to both the longitudinal axis and the orthogonal axis. If there is, between the two exhaust valves, in a state where the two exhaust valves do not protrude from the cylinder, to secure a space for disposing the glow plug, the diameter of each exhaust valve, Eventually, the inside diameter of the exhaust port extending from each exhaust valve must be reduced, so that the exhaust gas flow resistance in each exhaust port further increases, and the effect of using four exhaust valves is further reduced. There was also a problem.

An object of the present invention is to solve the above-described problems when four exhaust valves are provided.

[0008]

In order to achieve this technical object, the present invention provides a method of manufacturing a fuel cell system, comprising: providing a scavenging port for introducing new air into a lower part of a cylinder having a built-in piston; In a uniflow type two-stroke internal combustion engine comprising a cylinder head having four exhaust valves and an exhaust port extending from each exhaust valve toward one longitudinal side of the cylinder head, The inter-valve distance between the two exhaust valves far from the one longitudinal side surface is larger than the inter-valve distance between the two exhaust valves near the one longitudinal side surface of the four exhaust valves. " .

[0009]

As described above, the inter-valve distance between two exhaust valves far from one longitudinal side of the four exhaust valves is determined as follows.
By making the inter-valve distance between the two exhaust valves closer to one longitudinal side of the four exhaust valves larger, the two exhaust valves farther from one longitudinal side become two exhaust valves closer to one longitudinal side. Since it will be located outside than when, in the case of curving outward in the middle of both exhaust ports extending from the two exhaust valves far from the one longitudinal side,
Its outwardly curved dimension can be reliably reduced by the amount that the two exhaust valves far from the one longitudinal side are located outside the two exhaust valves near the one longitudinal side.

Therefore, according to the present invention, the outward bending of the two exhaust ports extending from one of the four exhaust valves to the one longitudinal side from the two exhaust valves farther from the one longitudinal side can be reduced, and, consequently, both the exhaust ports can be reduced. Since the flow resistance of the exhaust gas in the exhaust port can be greatly reduced, the effect of having four exhaust valves can be reliably achieved.

Further, as set forth in claim 2, the distance from two exhaust valves far from one longitudinal side of the four exhaust valves to a longitudinal axis extending in the crankshaft direction through the center of the cylinder is defined as: By making the distance between the two exhaust valves closer to one longitudinal side of the four exhaust valves and the longitudinal axis smaller than the distance from the one longitudinal side, the two exhaust valves farthest from the one longitudinal side can be extended through the center of the cylinder. As the distance between the two exhaust valves approaches the axis and the distance between the two exhaust valves does not protrude from the cylinder, the distance between the two exhaust valves can be increased. The space for disposing the glow plug can be ensured without reducing the diameter of the valve and, consequently, the inner diameter of the exhaust port extending from both exhaust valves.

Furthermore, as described in claim 3, the exhaust ports extending from the four exhaust valves are joined to one exhaust port and opened to the longitudinal side surface, so that the cylinder head can be cast when casting. Since the cores forming the respective exhaust ports can be integrated with respect to the four exhaust ports, the strength of the exhaust port core can be increased, and the exhaust port core can be cast. This has the advantage that it can be prevented from tilting or shifting at times.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In this figure, reference numeral 1 denotes a cylinder block provided with a cylinder 2, and reference numeral 3 denotes a cylinder head fastened to a top surface of the cylinder block 1 with a plurality of head bolts 4. A piston 5 having a combustion chamber 6 formed on the top surface thereof is provided so as to reciprocate.

A plurality of scavenging ports 7 are provided at the lower part of the cylinder 2 so as to be opened by the downward movement of the piston 5 therein. At the end of the process, new compressed air sent from a compressor (not shown) from the new air introduction passage 21 is blown out from each of the scavenging ports 7 into the cylinder 2.

On the other hand, the cylinder head 3 at the top of the cylinder 5 has a fuel injection nozzle 8 for injecting fuel into the combustion chamber 6 on the top surface at the end of the upward movement of the piston 5. The cylinder 2 in plan view
The four exhaust valves 9, 10, 11, and 12 which are provided at a position substantially at the center O and are configured to open at substantially the same time as the scavenging ports 7, connect the fuel injection nozzle 8 in a plan view. The cylinder head 3 is provided at an area surrounding the exhaust valves 9, 10,.
Exhaust ports 13, 14, 14, extending from each of 11, 12 toward one longitudinal side surface 3 a of the cylinder head 3.
15 and 16 are formed.

The four exhaust valves 9, 10, 1
Reference numerals 1 and 12 denote centers O of the cylinder 2 in plan view.
The two exhaust valves 9, 10, 11, and 12 are provided on the left and right sides of the longitudinal axis 17 extending in the direction of the crankshaft, and one of the four exhaust valves 9, 10, 11, and 12 in the cylinder head 3. Two exhaust valves 9 and 10 close to 3a and two exhaust valves 11 and 12 far from the one longitudinal side 3a are orthogonal axes extending in a direction perpendicular to the longitudinal axis 17 through the center O of the cylinder 2. 18 are arranged one by one on both sides on the left and right sides.

In this case, the four exhaust valves 9,
The inter-valve distance L2 between the two exhaust valves 11, 12 farthest from the one longitudinal side 3a of the one of the four exhaust valves 9, 10, 11, 12 is set to the one longitudinal side 3a of the four exhaust valves 9, 10, 11, 12. L1 between the two exhaust valves 9 and 10 close to
A glow plug 19 for starting ignition is provided at a portion between the two exhaust valves 11 and 12 farther from the one longitudinal side surface 3a so that the tip of the glow plug 19 looks substantially in the cylinder 2 at the center.

Further, the four exhaust valves 9, 10, 11,.
12, two exhaust valves 1 far from one longitudinal side 3a
The distance S2 from the first and second exhaust valves 9, 10, 11, 12 to the longitudinal axis 17 is determined by the distance between two exhaust valves 9, 10 near one longitudinal side surface 3 a of the four exhaust valves 9, 10, 11, 12.
7 is smaller than the distance S1.

In addition, each of the four exhaust valves 9, 1
Exhaust ports 13, 14, 1 extending from 0, 11, 12
5 and 16 are joined to one exhaust port 20 and are opened to the one longitudinal side surface 3a.

As described above, the four exhaust valves 9, 10, 1
The distance L2 between the two exhaust valves 11 and 12 farthest from one of the longitudinal side surfaces 3a of the two exhaust valves 9 and 1
By setting the inter-valve distance L1 between the two exhaust valves 9 and 10 closer to one longitudinal side 3a of 0, 11 and 12 larger than the two exhaust valves 11 and 12 farther from the one longitudinal side 3a.
Reference numeral 12 denotes two exhaust valves 9, 1 near one longitudinal side surface 3a.
0, the intermediate portions of the two exhaust ports 15, 16 extending from the two exhaust valves 11, 12 far from the one longitudinal side 3a are replaced with two exhaust ports near the one longitudinal side 3a. When outwardly curved so as to bypass the valves 9 and 10 so as to bypass the outside thereof, the outwardly curved dimension is set so that the two exhaust valves 11 and 12 far from the one longitudinal side surface 3a have one longitudinal side. The size can be surely reduced by an amount that is located outside the two exhaust valves 9 and 10 close to the side surface 3a.

Further, the four exhaust valves 9, 10, 11,
12, two exhaust valves 1 far from one longitudinal side 3a
The distance S2 from the first and second exhaust valves 9, 10, 11, 12 to the longitudinal axis 17 is determined by the distance between two exhaust valves 9, 10 near one longitudinal side surface 3 a of the four exhaust valves 9, 10, 11, 12.
7, the two exhaust valves 11 and 12 far from the one longitudinal side surface 3a are
Since the distance L2 between the exhaust valves 11 and 12 approaches the longitudinal axis 17 and the exhaust valves 11 and 12 do not protrude from the cylinder 2, the distance L2 between the exhaust valves 11 and 12 can be increased. At the portion between the two exhaust valves 11 and 12, the diameter of the two exhaust valves 11 and 12,
The space for disposing the glow plug 19 can be reliably secured without reducing the inner diameters of the exhaust ports 15 and 16 extending from the exhaust ports 1 and 12.

Further, each of the four exhaust valves 9, 10,.
Exhaust ports 13, 14, 15, 1 extending from 11, 12
6 is joined to one port 20 and opened at the one longitudinal side surface 3a, so that the core mold forming the exhaust ports 13, 14, 15, 16 at the time of casting the cylinder head 3, Four exhaust ports 13, 14, 1
Since the components 5 and 16 can be integrated, the strength of the core for the exhaust port can be increased,
It is possible to prevent the core mold for the exhaust port from being inclined or shifted during casting.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing an embodiment of the present invention.

FIG. 2 is a bottom view taken along the line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder 3 Cylinder head 5 Piston 7 Scavenging port 8 Fuel injection nozzle 9, 10, 11, 12 Exhaust valve 13, 14, 15, 16 Exhaust port 17 Longitudinal axis 18 Orthogonal axis 19 Glow plug 20 One exhaust port O Center of cylinder

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02F 1/24 F02F 1/24 DF Term (Reference) 3G016 AA03 AA14 AA17 BA05 BA08 CA13 CA41 CA56 CA57 CA60 FA03 GA00 3G023 AA00 AA19 AB03 AB05 AC05 AD04 AF02 3G024 AA04 AA11 AA15 DA02 DA12 EA01 FA00 GA04

Claims (3)

[Claims] A scavenging port for introducing new air into the cylinder is provided at a lower portion of a cylinder having a built-in piston, while four exhaust valves are provided at a cylinder head at a top of the cylinder, and each exhaust valve is connected to the cylinder by the exhaust valve. A uniflow type two-stroke internal combustion engine having an exhaust port extending toward one longitudinal side surface of the head, wherein the inter-valve distance between two exhaust valves of the four exhaust valves, which is far from the one longitudinal side surface, A uniflow-type two-stroke internal combustion engine, wherein the inter-valve distance between two of the four exhaust valves, which is closer to the one longitudinal side, is greater than the inter-valve distance. 2. The system according to claim 1, wherein a distance between two exhaust valves far from one longitudinal side surface of the four exhaust valves and a longitudinal axis extending in the crankshaft direction through the center of the cylinder is defined by the four exhaust valves. A structure of a uniflow type two-stroke internal combustion engine, wherein a distance between two exhaust valves closer to one longitudinal side of the exhaust valves and the longitudinal axis is smaller. 3. The uniflow type two-stroke internal combustion engine according to claim 1, wherein the exhaust ports extending from the four exhaust valves are joined to one exhaust port and opened on the longitudinal side surface. Institutional structure.