JP2001065353A - Structure of uniflow two-cycle internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a lubricant flowing out from an scavenging port to the outside of a cylinder, from being temporarily stored on an inner bottom of a scavenging chamber and returning to the cylinder again, and to prevent the abnormal combustion of the lubricant by providing the scavenging chamber with an inclined inner bottom obliquely upwardly inclined toward an air inlet of the scavenging chamber. SOLUTION: A combustion chamber 6 is recessed to reciprocatably accommodate a piston 5 inside of a cylinder 2. Two or more scavenging ports 7 capable of being opened and closed by the reciprocation of the piston 5 are formed in an inclined state. Further a cylinder block 1 is provided with a scavenging chamber 8 surrounding the scavenging ports 7. On this occasion, an inner bottom of the scavenging chamber 8 is formed as an inclined inner bottom 16 obliquely upwardly inclined to the left and right outward directions from the cylinder 2. A raised part 17 upwardly projecting from an end of the inclined inner bottom 16 with a proper height H, is formed on a part to be joined to an air inlet 10 of a new air supply path 11.

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 having a scavenging port at the lower part of a cylinder for introducing new air into the cylinder and an exhaust valve at the top of the cylinder. Things.

[0002]

2. Description of the Related Art Generally, in a uniflow type two-stroke internal combustion engine of this type, a plurality of scavenging ports in a lower portion of a cylinder are opened at the end of a downward movement of a piston due to an explosion stroke, as is well known. At the same time, when the exhaust valve at the top of the cylinder is opened, scavenging of discharging exhaust gas in the cylinder from the exhaust valve while introducing new air from each of the scavenging ports into the cylinder is performed. At this time, the scavenging port is closed, and the exhaust valve is closed to shift to the compression stroke. Since the piston inside the cylinder reciprocates to open and close each scavenging port at the lower part of the cylinder, the scavenging port is closed. The lubricating oil scraped off from the inner surface of the cylinder by the piston ring provided on the reciprocating piston flows Inclusive, the lubricating oil, so that accumulated in the inner bottom surface of the scavenging chamber surrounding the periphery of the respective scavenging port.

[0003] When the amount of lubricating oil accumulated on the inner bottom surface of the scavenging chamber increases, the lubricating oil enters the cylinder again through each scavenging port together with fresh air, causing abnormal combustion in the cylinder. appear.

Therefore, Japanese Patent Application Laid-Open No. 9-28 as a prior art is disclosed.
No. 0103 discloses an oil reservoir provided at a lower portion of the scavenging chamber, and an oil relief valve which is opened when the operation of the internal combustion engine is stopped is provided in an oil passage from the bottom of the oil reservoir to the crank chamber. By doing so, it is proposed to avoid the occurrence of the inconvenience.

[0005]

However, in the method according to the prior art, the lubricating oil accumulated in the oil reservoir is released to the crank chamber by an oil relief valve when the operation of the internal combustion engine is stopped. In the cylinder block, an oil reservoir and an oil passage from the oil reservoir to the crank chamber must be formed, which not only complicates the structure of the cylinder block but also increases the weight thereof. In addition, since an oil relief valve that is opened when the operation of the internal combustion engine is stopped is required, there is a problem that the number of parts and the number of assembly steps are increased.

An object of the present invention is to solve these problems.

[0007]

In order to achieve the above technical object, the present invention provides a fuel cell system having an exhaust valve and a fuel injection nozzle provided at the top of a cylinder having a reciprocating piston.
At the lower part of the cylinder, a plurality of scavenging ports are bored into the cylinder, and a scavenging chamber surrounding the outside of each scavenging port is provided. At the air inlet to the scavenging chamber, new air supply from a scavenging pump is provided. In a uniflow type two-stroke internal combustion engine having connected passages, an inner bottom surface of the scavenging chamber is formed as an inclined inner bottom surface that is inclined obliquely upward toward an air inlet of the scavenging chamber. ].

[0008]

As described above, the inner bottom surface of the scavenging chamber is formed on the inclined inner bottom surface which is inclined obliquely upward toward the air inlet of the scavenging chamber. The flowing out lubricating oil is collected by the inclined inner bottom surface so as to approach each of the scavenging ports, and is continuously returned to the cylinder again along with new air flowing into the cylinder from each scavenging port. Accordingly, it is possible to reliably reduce a large amount of lubricating oil accumulated on the inner bottom surface of the scavenging chamber and returning to the cylinder at once.

Therefore, according to the present invention, in a uniflow type two-stroke internal combustion engine, abnormal combustion due to lubricating oil in the cylinder is prevented with an extremely simple configuration in which the inner bottom surface of the scavenging chamber is formed as an inclined surface. In other words, there is the effect that the cylinder block structure can be surely achieved without complicating the structure and increasing the weight of the cylinder block, and increasing the number of parts and the number of assembly steps.

According to a second aspect of the present invention, a protrusion is provided at the air inlet of the new air supply passage or the scavenging chamber so as to protrude upward by an appropriate dimension from the end of the inclined inner bottom surface. Since the lubricating oil at the inclined inner bottom surface can be reliably prevented from flowing to the upstream side of the new air supply passage by the raised portion,
In addition to the above effects, it is possible to prevent the scavenging pump on the upstream side of the new air supply passage from being excessively supplied with the lubricating oil and causing a problem in the scavenging pump.

[0011]

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 by 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 which are opened and closed by a reciprocating motion of a piston 5 inside the cylinder 2 are formed in a lower portion of the cylinder 2 so as to be inclined obliquely upward and downward. 1, a scavenging chamber 8 is formed so as to surround a portion of each of the scavenging ports 7 of the cylinder 2, and a cooling water jacket 9 is configured to surround an upper portion of the cylinder 2. Further, an air inlet 10 to the scavenging chamber 8 is opened on a side surface of the cylinder block 1, and a new air supply passage 11 from a scavenging pump (not shown) is connected to the air inlet 10. I have.

On the other hand, the cylinder head 3 at the top of the cylinder 2 has a plurality of exhaust valves 12, an exhaust port 13 extending from each of the exhaust valves 12 toward the side surface of the cylinder head 3, and The fuel injection nozzle 14 and a glow plug 15 for starting ignition are provided.

The inner bottom surface of the scavenging chamber 8 is
While being formed on the inclined inner bottom surface 16 which is inclined upward at an appropriate angle with respect to the horizontal plane from the cylinder 2 toward both the left and right outwards, a portion of the new air supply passage 11 which is joined to the air inlet 10 is A protrusion 17 is provided which protrudes upward from the end of the inclined inner bottom surface 16 by an appropriate dimension H as appropriate.

Thus, the inner bottom surface of the scavenging chamber 8 is
The lubricating oil flowing from the scavenging ports 7 to the outside of the cylinder 2 is formed on the inclined inner bottom surface 16 which is inclined obliquely upward at an appropriate angle with respect to a horizontal plane from the cylinder 2 toward both the left and right sides. The slanted inner bottom surface 16 is collected so as to approach each of the scavenging ports 7, and is continuously returned to the cylinder 2 again with the new air flowing into the cylinder 2 from each scavenging port 7. Therefore, it is possible to reliably reduce a large amount of lubricating oil accumulated on the inner bottom surface of the scavenging chamber 8 and returning to the cylinder 2 at one time.

Further, a protruding portion 17 which protrudes upward by an appropriate dimension H from the end of the inclined inner bottom surface 16 is provided at a portion of the new air supply passage 11 which is joined to the air inlet 10 so that the inclined portion 17 is provided. That the lubricating oil at the inner bottom surface 16 flows out to the upstream side of the new air supply passage 11,
The protrusion 17 can be reliably prevented by the protrusion 17, and the protrusion 17 is provided on the inner bottom surface of the air inlet 10 to the scavenging chamber 8 instead of being provided on the new air supply passage 11 side. You may do it.

[Brief description of the drawings]

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

FIG. 2 is a plan sectional view taken along line II-II of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 cylinder block 2 cylinder 3 cylinder head 5 piston 7 scavenging port 8 scavenging chamber 10 air inlet to scavenging chamber 11 new air supply passage 12 exhaust valve 14 fuel injection nozzle 16 inclined inner bottom surface of scavenging chamber 17 ridge

Claims (2)

[Claims] An exhaust valve and a fuel injection nozzle are provided at the top of a cylinder having a reciprocating piston, and a plurality of scavenging ports are bored into the cylinder below the cylinder. In a uniflow type two-stroke internal combustion engine in which a scavenging chamber surrounding the scavenging port is provided, and a new air supply passage from a scavenging pump is connected to an air inlet to the scavenging chamber, the inner bottom surface of the scavenging chamber is A structure of a uniflow type two-stroke internal combustion engine, characterized in that it is formed on an inclined inner bottom surface inclined obliquely upward toward an air inlet in a scavenging chamber. 2. The method according to claim 1, wherein a protrusion is provided at the air inlet of the new air supply passage or the scavenging chamber so as to protrude upward by an appropriate dimension from the end of the inclined inner bottom surface. Of a uniflow type two-stroke internal combustion engine.