Internal-combustion engines – Two-cycle – Whirl through piston-controlled ports
Patent
1997-12-09
2000-01-25
Kamen, Noah P.
Internal-combustion engines
Two-cycle
Whirl through piston-controlled ports
123 65P, 123 73PP, 1231821, F02B 3304
Patent
active
060167769
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The subject invention refers to a cylinder for a two-stroke combustion engine intended for a handheld working tool, preferably a chain saw.
BACKGROUND OF THE INVENTION
Engines for handheld working tools are often of the two-stroke type and very compactly designed, because the tool should naturally be as light and compact as possible. This aim permeates the design of all of the tool's components, including the cylinder's. Thus, cylinders for portable working tools, such as chain saws, have as a rule a very simple and compact design. This simplicity leads to a compact design and low production costs. At the same time it also leads to a fuel consumption and to exhaust emissions, which leaves a deal to be desired, especially as the requirements for low exhaust emissions gradually increase.
PURPOSE OF THE INVENTION
The purpose of the subject invention is to create a cylinder, which substantially reduces the above outlined problems, at the same time as it enables a compact design of the handheld working tool.
SUMMARY OF THE INVENTION
The above purpose is achieved in a cylinder in accordance with the invention having the characteristics appearing from the appended claims.
The cylinder in accordance with the invention is thus essentially characterized in that the mouth of the exhaust port inside the cylinder as well as the cylinder's transfer ports are symmetrically arranged around a common symmetry plane, which follows the cylinder's symmetry axis, and at the mouth of the exhaust port on the outside of the cylinder a fastening plane with fastening holes is embodied for a directly mounted muffler, and the fastening plane is essentially perpendicular to the symmetry plane, and that the exhaust port is angled sideways in relation to the symmetry plane and its mouth is shifted sideways in relation to the symmetry plane. Low scavenging losses are obtained by means of that the mouth of the exhaust port and the cylinder's transfer ports are arranged symmetrically around a common symmetry plane. Since the exhaust port is angled sideways in relation to the symmetry plane and its mouth being shifted sideways in relation to the symmetry plane, conditions for making room for an effective, directly mounted muffler are created, suitably supplied with a catalytic converter.
Furthermore, suitably the cylinder's inlet port as well as its exhaust port incline downwards in the flow direction in relation to a plane perpendicular to the axial direction of the cylinder bore. This contributes to effective gas flows in the engine and low losses. For the same reasons, suitably the cylinder is also supplied with four closed and ready cast transfer ports. By these measures and by an especially favorable positioning of a possible decompression valve, a cylinder is created with an unusually high efficiency for a handheld working tool. Some of these measures are known from other two-stroke engines, but they are not known for a cylinder for a handheld working tool, considering the special demands on such a tool.
Further characteristics and advantages of the invention will be apparent from the following description of various preferred embodiments. These will be more apparent with the support of the enclosed drawing figures.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be described in closer detail in the following by way of various embodiments thereof with reference to the accompanying drawing figures, in which the same numbers in the different figures state one another's corresponding parts.
FIG. 1 shows a cross section of the cylinder seen from the side, in accordance with the subject invention.
FIG. 2 shows a cross section of the cylinder in FIG. 1 along line A--A.
FIG. 3 shows the cylinder, in accordance with FIGS. 1 and 2, seen from the side, in the direction towards its inlet port. A partial cross section is made in order to illustrate a port intended for a decompression valve. For the sake of clarity, the valve is illustrated located outside the port in which it usually is mounted.
In FIG. 1, numeral
REFERENCES:
patent: 2742380 (1956-04-01), Peters
patent: 4026254 (1977-05-01), Ehrlich
patent: 4121552 (1978-10-01), Mithuo et al.
patent: 4178886 (1979-12-01), Uchinishi
patent: 4353333 (1982-10-01), Iio
patent: 4730540 (1988-03-01), Kinouchi
patent: 5025760 (1991-06-01), Webb et al.
patent: 5048290 (1991-09-01), Lavenius et al.
patent: 5211140 (1993-05-01), Hironaka et al.
patent: 5361738 (1994-11-01), Iida
patent: 5870981 (1999-02-01), Knaus et al.
Aktiebolaget Electrolux
Huynh Hai
Kamen Noah P.
LandOfFree
Cylinder does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cylinder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cylinder will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2309813