DE3215169A1 - Two-stroke reciprocating piston internal combustion engine - Google Patents

Description

FICHTEL & SACHS AG - SOHWEINFURT ANR 1 001 485 - Reg.No. 11 914

PATENT ^ AND UTILITY PATTERN APPLICATION

TWO-STROKE PISTON COMBUSTION MACHINE

The invention relates to a two-stroke Huhkolben ^ internal combustion engine with an outlet opening arranged in the cylinder wall and controlled by the piston,

Motors designed in this way are often used to drive gardening and hobby tools. For cost reasons, Such devices usually used a manually operated pull starter. The ones required for such a start-up process However, forces increase with the increase in the displacement of the engine, because that is necessary to achieve an operationally normal The required compression ratio of the engine as such cannot be reduced during the starting process. Physically less capable users of devices that are equipped with motors that can be started by means of a cable have then more or less great difficulties to get the internal combustion engine going by hand, - It has already become known to facilitate the starting process for two-stroke reciprocating engines use a so-called decompression valve in each case. The establishment of such a decompression valve is, however not without disadvantages, so this valve must be operated separately by hand with each starting process, or - with one semi-automatic actuation of the decompression valve, e.g. via the starter rope, can occur if it is not actuated carefully different start-up difficulties occur with this facility.

The object of the invention is, inter alia, the aforementioned Difficulties without expensive precautions on the internal combustion engine to avoid.

3215163

The solution to this problem is iiP characteristic of the 3 main claim specified.

The starting process can now be carried out by means of a manually operated pull starter can be made much easier. According to the invention, a noticeable decompression occurs only at a low, When the engine is started, the speed is present, thereby facilitating the starting process at the operating speed of the internal combustion engine on the other hand, the decompression practically does not appear and it is only negligibly lower Loss of performance a.

Further advantageous and expedient details of the invention emerge from the features of the respective subclaims.

The invention is explained in more detail below with reference to two embodiments. It shows:

1 shows a cylinder of a two-stroke reciprocating internal combustion engine in longitudinal section with a connecting channel in the form of a bore between the compression space and the overflow channel;

2 shows the cylinder of a two-stroke reciprocating piston internal combustion engine in longitudinal section with a separate connecting channel in the form of a groove parallel to the cylinder axis between the compression chamber and exhaust port.

In Fig. 1, 1 is generally an engine cylinder of a two-stroke reciprocating internal combustion engine denotes, consisting of a cylinder part 2 with a cylinder head held by means of studs 3j in which a spark plug 11 is arranged. The cylinder bore 2a receives a piston 4 with piston rings 5, the piston in the present FIG. 1 being at bottom dead center is drawn. Furthermore, the connecting rod 6 engaging the piston via a piston pin and the connecting rod 6 are in roller bearings in the cylinder 1 recorded crankshaft 7 can be seen. Furthermore, the cylinder has an outlet opening 8 in the wall of its bore 2a and the branches 9a and 9b of the over «* flow channel 9 from the crankcase pump, not shown here ,

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The cylinder bore 2a has a bore 10. which in the lower Area of the compression space 2b starts and, running at an angle, a connection of the cylinder bore 2a with the one Branch 9a of the overflow channel 9 produces.

Instead of the above-described bore 10, it is also possible to have one in the cylinder bore 2a in the direction of the cylinder axis to provide extending groove as a connection between the compression chamber 2b and one branch of the overflow channel 9, the The confluence of this groove in the cylinder bore as well as the passage dimensions are designed to correspond to those of the mentioned bore are,

In Fig, 2 is another embodiment of a two-stroke reciprocating internal combustion engine shown with one-piece cylinder 21, the cylinder as a die-cast part made of special light metal with corresponding surface treatment of the cylinder bore 21a is made. The received in the cylinder bore 21a Piston 22 with piston ring 23 is connected to crankshaft 25 via a piston pin and a connecting rod 24, which latter is mounted in a conventional manner in the base of the cylinder. The piston 22 is located in the cylinder bore 21a in the top dead center position. A spark plug 30 protrudes into the compression space 21b above the piston. Below of the piston 22, an intake duct 26 with a throttle valve can be seen, while the one mounted opposite the intake duct ™ Outlet channel 27 covered by the piston 22 in its designated position will.

In the cylinder bore 21a, a groove 29 is provided, which extends in the direction of the cylinder ^ longitudinal axis and a connection between the compression chamber 21b and the outlet channel 27 forms. In the "top dead center" position assumed by the piston 22 is both the connecting groove 29 opening into the lower region of the compression space 21b and the outlet channel covered by the piston,

In the case of a die-cast cylinder, the connecting groove 29 is expediently molded in during manufacture.

It is also possible instead of the connecting groove described above to provide an inclined bore as a connecting channel between the compression chamber 21b and the outlet channel 27, the The mouth of such a bore is provided at the level of the beginning of the connecting groove 29 in the lower region of the compression space 21b will.

With such a connection channel, designed as a bore or as a groove in the cylinder wall, a connection between the compression chamber of the cylinder and either the overflow channel or the outlet channel of the internal combustion engine, i.e., a gas guide chamber with less Pressure as compression pressure, produced and closed by the piston during further upward travel. - Appropriately, the connecting bore or the connecting groove is arranged in the cylinder bore in such a way that the bore mouth or the beginning of the connecting groove is approximately 14 ... 22 mm below the upper edge of the piston in its top dead center position with a stroke of 6O ... 7O mm comes to rest. A through cross-section corresponding to a bore of approximately 3 ».. 4 mm Φ is favorable for a bore or a connecting groove. The position of the opening of the bore or of the connecting groove depends essentially on the extent to which the manual starting process is to be facilitated.

In any case, the connection channel described above between the compression chamber of the cylinder and the overflow channel or, the outlet channel a facilitating the manual starting process Decompression achieved, which only appears at the low starting speed. At operating speed, on the other hand, the Decompression made possible by the connecting channel hardly occurs, there is only a negligible, small loss of performance the internal combustion engine.

06.04.1982
FRF-3 Schu / whm '

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Claims (6)

FICHTEL & SACHS AG - SCHWEINFURT ANR 1 001 485 Reg.-No. 11 9l4 PATENT CLAIMS Two-stroke reciprocating internal combustion engine with an exhaust port in the cylinder wall controlled by the piston, dad, gek., That a separate channel of small cross-section between the compression chamber of the cylinder and at least a smaller one Pressure is provided as the building up compression pressure standing gas guide space of the engine. 2. Two-stroke reciprocating internal combustion engine according to claim 1, dad, gek. that the separate connecting channel (10; 29) can only be controlled in its passage by the piston (4j 22), 3. Two-stroke reciprocating internal combustion engine according to claim 1 or 2, dad. gek. That the separate channel (10) a connection between the compression chamber (2b) of the cylinder (2a) and the Overflow channel (9) produces. (Fig. 1) 4. Two-stroke reciprocating internal combustion engine according to claim 1 or 2, dad. gek. That the separate channel (29) a connection between the compression space (21b) of the cylinder (21a) and the outlet channel (27). (Fig. 2) 5. Two-stroke reciprocating internal combustion engine according to claim 3, dad. gek. That the connecting channel in the form of a bore (10) running obliquely from the compression chamber. (2b) of the cylinder (2a) is guided to a branch (9a) of the overflow channel (9). (Fig. 1) 6. Two-stroke reciprocating internal combustion engine according to claim 3, dad, gek. That the connecting channel is designed in the form of a groove axially parallel to the wall of the cylinder, which is in the compression chamber beginning of the cylinder, extends axially to the transfer channel. Two-stroke reciprocating internal combustion engine according to claim 4, dad. gek. That the separate connecting channel as a sloping bore between the compression chamber of the cylinder and the associated outlet channel is formed, Two-stroke reciprocating internal combustion engine according to claim 4, dad. gek. That the separate connecting channel in the form of an in the wall of the cylinder (21a) is designed axially parallel to the groove (29) in the compression chamber (21b) of the cylinder (21a) extending into the outlet channel (27) opening. (Fig. 2) 04/06/1982
FRP-3 Schu / whm "