DE2639821A1 - Two stroke IC engine - has additional air fuel mixture intake slots to guide fuel mixture against rear of piston guide plate - Google Patents

Abstract

Cylinder (18) has an inlet (26) and exhaust (28) ports arranged diametrically opposite to each other and regulated by the piston movement. The inlet port communicates with the crankcase by the usual transfer channel (30). The piston crown (46) carries an upwards projecting guide piece (48) off set to the cylinder axis. The guide is arranged between the inlet and exhaust ports and serves to guide the incoming gases to the cylinder head to effect an improved scavenging action, which is additionally improved, particularly in the dead region (50) behind the guide piece by providing auxiliary inlet openings (52) in the cylinder wall and regulated by the piston movement.

Description

PATENT ANWXLTE

DR.-IN G. H. FINCKE DIPL.-ING. H. BOHR DIPL.-ING. S. STAEGER

DR. Rer. nat. R. KNEISSL

Patent Attorney Dr. Find · ■ Bohr · Staeger -8 Munich 5 · MOtlerstraSe

8 MONKS 5. Müllerstrasse 31 Telephone: (089) * 2660 «0 telegrams: Claims Munich Telex: 523903 claim d

Folder No: A Please state in the answer

3rd September 1976

description

of Mr. John C. Perry Carlsbad, California / USA

concerning

¹¹ Two-stroke internal combustion engine with guide wall piston and method for increasing the output of the same ".

Priority: 3/9/1975 - USA

The invention relates generally to internal combustion engines, and more particularly a method and means by which the performance of a baffle piston two-stroke internal combustion engine is substantial can be increased.

As is known, a two-stroke internal combustion engine has a KoI-

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Bank details: Bayer. Vereinsbank Munich, account 620 404 ■ Postal check account: Munich 270 44-802

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ben, which alternately performs compression and power strokes, and a combined inlet-outlet phase during an end portion each working stroke and an initial part of the following compression stroke of the piston. During this inlet-outlet phase the piston releases inlet and outlet slots in the cylinder wall to remove the used combustion gases from the cylinder to push out through the outlet slot or the outlet slots and to allow the fuel-air mixture to enter, the following is also referred to as a combustible mixture, to be allowed to enter the cylinder through the inlet slot or the inlet slots. During each piston compression stroke, a negative pressure is created in the crankcase of the engine, which creates an intake air flow through the engine carburetor in the crankcase to form a charge of combustible mixture in this. This Combustible mixture is compressed in the crankcase during the following piston working stroke and then through into the engine cylinder displaces the cylinder intake slots during the next intake exhaust phase of the engine.

In the two-stroke process, there is a particular problem to which the invention is directed. This is the problem to flush the used combustion gases out of the cylinder and charging the cylinder with combustible mixture during each intake-exhaust phase of the engine. Therefore it takes place at one Two-stroke engine the expulsion of the used combustion gases and the entry of the combustible mixture essentially simultaneously with the exception, of course, that the expulsion of the burnt gases a little before the entry of the combustible mixture happens, which is due to the fact that the release of the outlet slots by the piston begins a little before the inlet slots. The used combustion gases are released from the cylinder rather by the combustible mixture entering than by inevitable Displacement flushed out like a four-stroke engine. Because the volume of the residual gas that is in the cylinder at the end of each intake-exhaust phase remains, the line developed by the engine

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reduced performance is an effective purging of the residual gas during each intake-exhaust phase for satisfactory engine operation essential.

In an effort to improve this residual gas purging effect and thereby A variety of two-stroke engine designs have become available to increase engine performance developed. Two of these motor types that are most widely used are commonly referred to as the Schnierly slot motor and referred to as a baffle piston engine. With the Schnierly slot motor A special arrangement of the cylinder inlet and outlet slots is provided for effective flushing. In the piston piston engine there is a protruding baffle on the piston between diametrically opposed inlet and Outlet slots provided to provide effective flushing. Through this baffle, the combustible mixture entering during each intake-exhaust phase of the engine becomes the cylinder head diverted to purge residual gas from the cylinder head area.

The invention is based on the object of providing such improvements in the last-mentioned guide wall piston engine that one Deficiency peculiar to this type of engine is remedied. This deficiency consists in the fact that the diversion of the incoming combustible mixture through the piston baffle in the area behind the baffle, based on the cylinder inlet openings, i. in the area on the opposite of the inlet openings Side of the baffle, a relatively dead zone is created from which the burnt combustion gases are not purged. That in this area at the end of each intake-exhaust phase of the engine remaining residual gas represents a substantial loss of potential In other words, it would if this area contains a flammable mixture instead of residual gas. would be the total volume of the mixture in the cylinder at ignition and thus the engine performance can be increased significantly. One such improvement at a modest cost is the baffle piston engine the Schnferly slot motor because of the relatively high cost of the

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superior to the latter design.

The invention brings such improvements to a two-stroke piston baffle engine with it that the normally dead residual gas-filled area behind the KoIbenleitwand is flushed by combustible mixture in this area during each inlet-outlet phase of the engine. According to the preferred embodiment of the invention, the combustible mixture is against the back the baffle, both to more effectively flush the area immediately behind the baffle and to reduce the loss of combustibles Reduce the mixture through the outlet openings to a minimum.

In the preferred engine described, the combustible mixture is relatively narrow in the area behind the piston baffle slot-like auxiliary inlet openings are introduced into the cylinder wall adjacent the ends and immediately behind the baffle. These openings are arranged in planes that face the cylinder axis are parallel and inclined to the baffle and via auxiliary inlet channels around the cylinder with the crankcase chamber in Connected. During engine operation, the auxiliary intake ports are opened through the piston during each intake-exhaust phase of the engine is released and the combustible mixture is blown through these openings into the area behind the piston baffle or directed to purge residual gas from this area. The incoming mixture is slanted into the back of the baffle directed to thoroughly flush the area immediately behind the baffle and the loss of mixture due to the then released Reduce outlet openings to a minimum.

It will be seen from the following that the improvements according to the invention are applied to any piston baffle two-stroke engine can be. The invention is described below in connection with a baffle piston two-stroke engine of the type such as

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it is used in remote-controlled model airplanes and the like. In the accompanying drawings show:

Fig; 1 is a side view of a two-stroke internal combustion engine according to the invention with baffle piston;

Fig. 2 is a sectional view of the internal combustion engine;

3 shows, on an enlarged scale, a view in section along the line 3-3 in FIG. 2;

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

4 shows a partial view in section and in a perspective representation of the motor.

In the drawings, a guide wall piston two-stroke engine 10 is shown, the body 12 of which has an upper, externally ribbed cylinder part 14 and a lower crankcase 16. The cylinder part 14 includes a cylinder bore 18, hereinafter simply called a cylinder and the one at one end is completed by a removable cylinder head 20 and at its other end to the crankcase chamber 22 in the engine crankcase 16 is open.

Inside the cylinder 18 is a piston 24, which by alternating compression strokes to the head 20 and working strokes, from Head is movable away. The engine work cycles have a combined one Inlet-outlet phase during an end portion of each piston power stroke and an initial portion of the piston compression stroke. In the wall of the cylinder 18 are diametrically opposed Inlet ports 26 and outlet ports 28 are provided which are exposed by the piston during each intake-exhaust phase of the engine.

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will give. The inlet ports 26 are with the engine crankcase chamber 22 via an inlet channel 30 in connection. The outlet openings 28 open into an outlet channel 32 on the engine body 12. When the piston 24 is at the lower end of its stroke, as shown in Fig. 2, the crankcase chamber is 22 also to the inlet channel 30 via openings 34 in the piston side wall and cover openings (not shown) in the wall of the cylinder in communication.

An engine output shaft is coaxial in engine crankcase 16 36, one end of which extends out of the crankcase as shown. At the inner end of the shaft is a counterweight crank 38 is provided within the crankcase chamber 22, with which the piston 24 is driven by a connecting rod 40 is connected so that the shaft is driven to rotate by the reciprocating movement of the piston in its cubes will.

During each compression stroke of the piston 24 to the cylinder head 20, a negative pressure is generated in the crankcase chamber 22, the air flow into the chamber 22 through a carburetor 42 that mixes fuel with the air to form a combustible mixture (Fuel-air-Geraisch) to form, and an inlet valve assembly (not shown) brings about. This valve arrangement is described in somewhat more detail below and only for the time being stated that it opens during each compression stroke of the piston and releases combustible mixture into the crankcase chamber lets enter.

During each power stroke of the piston away from the cylinder head 20, the intake valve assembly closes, thereby releasing the combustible mixture is initially compressed in the crankcase chamber 22 by the piston, whereupon it is in the cylinder 18 when the Inlet ports 26 through the piston during the inlet-outlet phase

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of the engine can occur. The combustible mixture is compressed in the cylinder during the next compression stroke of the piston and then ignited by a spark plug 44 on the cylinder head to drive the piston on its power stroke. That consumed Combustion gas of this working stroke is expelled from the cylinder through the outlet openings 28 when these openings during the following intake-exhaust phase of the engine.

As mentioned, and as is known to those skilled in the art, the operation of a two-stroke engine with high efficiency requires effective cleaning or purging of the residual gases from the cylinder by the combustible mixture during each intake-exhaust phase of the engine. For this purpose, in the known two-stroke engines, the outlet openings 28 are arranged somewhat closer to the cylinder head 20 than the inlet openings 26, as shown in connection with FIG to vent before releasing the inlet openings for the entry of the combustible mixture. The cylinder pressure is reduced before the inlet openings are released to cause the inflow of the compressed combustible mixture into the cylinder from the intake port 30 when the inlet openings are released ,, also be borne by the end face 46 of the piston 24 has a protruding guide wall 48 _β the is arranged in a plane which is parallel to the cylinder axis and extends between the inlet and outlet ports. This baffle is offset from the cylinder axis to the inlet openings and causes a deflection of the combustible mixture entering the cylinder through the last-mentioned openings to the cylinder head " as indicated by the parts drawn with full lines in FIGS. 2 and 4, in order to remove the residual gas from the To rinse out the head area of the cylinder, as indicated by the arrows drawn with dashed lines in the figures mentioned.

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The engine 10 described so far is conventional. From the previous Description of the engine it is apparent that during each intake-exhaust phase of the engine, the exhaust ports 28 through first the piston 24 are released to vent the combusted gases from the cylinder 18, whereupon the inlet ports 26 are released to allow compressed combustible mixture to enter. The piston guide wall 48 directs the incoming mixture to Cylinder head 20 to purge the residual gas from the cylinder.

However, this guide wall piston engine has a disadvantage which is intended to be remedied by the invention. This disadvantage is based in the fact that the deflection of the combustible mixture entering through the piston baffle 48 behind the latter with Relative to the inlet openings a relatively static residual gas-filled Forms area 50 from which the residual gas is not expelled by the combustible mixture. The volume of the residual gas, that remains in this area at the end of each intake-exhaust phase, of course, has a substantial reduction in engine performance result.

According to the invention, the described disadvantage of the known two-stroke baffle-wall piston engine is remedied by the fact that additional compressed combustible mixture from the engine crankcase 22 in the area 50 through auxiliary inlet openings 52 in the wall of the cylinder 18 during each intake-exhaust phase of the engine in the in Fig. 3 and 4 illustrated manner is initiated. This additional or auxiliary mixture flushes the residual gas out of the area and thereby significantly increases the engine performance. It has been found that the increase in engine power is about 20% to 30%. Preferably, the auxiliary openings 52 guide the incoming combustible mixture to and against the back of Kolbenleitwand 48 from each end of the baffle, as shown in the drawings, _e to residual gas from the region immediately

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rinse behind the baffle. Through this procedure the Introduction of additional combustible mixture or auxiliary mixture In the area 50 there is also a loss of mixture due to the Outlet openings 28 avoided.

As mentioned, and as can be seen from the preceding description As a result, the improvements of the present invention can be provided in virtually all, if not all, two-stroke engines. the Invention is therefore not to be applied to the illustrated limited to a particular two-stroke engine, which is a small two-stroke engine of the kind he is Used in remote-controlled model airplanes and the like. This The illustrated two-stroke engine is described below in somewhat more detail with regard to the improvements according to the invention. With the exception of these improvements, the engine is of a conventional type and a detailed description thereof is provided here unnecessary.

The engine body 12 is a cast body on which the cylinder head 20 is releasably attached by screws or the like. In a hole 54 of the cylinder part 14, a hardened cylinder liner can be removed 56 used, which forms the cylinder 18. This bushing is axially in the bore 54 by a shoulder 58 on End of the liner held adjacent the cylinder head, which shoulder in a recess 60 at the adjacent end of the Bore is seated. The opposite end of the liner ends just before the crankcase chamber 22. The cylinder liner 56 has openings, which inlet openings 26 and outlet openings 28 form.

The outlet openings 28 are in overlap with the outlet opening 62 through the outlet channel 32. The inlet channel 30, to which the inlet openings 26 are open, is formed by a recess 64 formed, which in the wall of the bore 54 through the cylinder

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part 14 of the cast body 12 is formed and extends down to the crankcase chamber 22. The inlet port is on his Outside bounded by the wall of the recess 64 and on its inside by the cylinder liner 56, which the closes the open inner side of the recess and covers it. The lower end of the inlet carial opens into the crankcase chamber immediately below the bottom of the can.

The rear end of the crankcase chamber 22 is closed by a rear end portion 66 which is connected to the crankcase is screwed. An engine body part 68 is bolted to the front end of the crankcase and has a bearing (not shown). contains, in which the motor shaft 36 is mounted, and an inlet opening (not shown) which is provided with an opening (not shown) cooperates in the shaft to form the aforementioned engine intake valve assembly. As mentioned before, opens this valve assembly during each compression stroke of the engine piston 14 and closes during each power stroke of the Piston. The engine carburetor 42 is disposed on the front body portion 68 so that its fuel air outlet is aligned with the inlet port is in communication with the intake valve assembly.

The above-described design of the motor shown is conventional. According to the invention, the engine is through the training the auxiliary inlet openings 52 in the cylinder liner 56 and improved by the formation of auxiliary inlet channels 7O, which are connected to the openings to the main inlet channel 30. The auxiliary openings are in the wall of the liner 56 shaped at the same height as the main inlet ports 26 so that the main and auxiliary inlet ports through the piston 24 can be released and covered at the same time. The auxiliary openings are immediately behind the level of the piston guide wall Arranged 48, as mentioned, the auxiliary openings preferably guide the auxiliary fuel mixture in the area 50 to and against

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the back of the baffle. For this purpose are the openings relatively narrow slots, the width of which is less than the wall thickness of the cylinder liner 56 and which are inclined to the plane of the piston baffle are inclined to the flammable mixture obliquely against the back of the baffle in the In the manner shown in the drawings. Since the auxiliary openings are relatively narrow, they are preferably at each end Two openings are provided as shown in the baffle to allow adequate volumetric flow of combustible mixture in to get the area 50. In some engines, however, the auxiliary openings can be made sufficiently wide without its flow conductivity is lost to allow the use of a single opening at each end of the baffle. Other auxiliary mixture inlets are also within the scope of the invention or inlet port arrangements possible.

The auxiliary inlet channels 70 are formed by circumferential depressions 72 (Fig. 3A) are formed in the wall of the engine body bore 54 and extend around the cylinder liner 56 from the top End of main inlet channel 30 to auxiliary inlet ports 52.

These auxiliary inlet channels are delimited on their outer sides by the cylinder liner, which is above the open inner sides of the recesses, and this closes.

As can be seen from the foregoing, during operation of the illustrated engine 10, the motor 10 in the crankcase chamber 22 combustible mixture entering the chamber from the engine carburetor 42 during each compression stroke of the piston 24 during of the following working stroke of the piston and then compressed into the cylinder 18 through the intake ports during the intake-exhaust phase 26, 52 let in. That through the main inlet port ~ -. openings 26 entering combustible mixture is deflected to the head area of the cylinder by the KoIbenleitwand 48 in order to use Purge combustion gas from this area. That

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combustible mixture entering through auxiliary inlet ports 52 acts on the back of the baffle and flushes residual gas from the area 50 behind the baffle. Through this latter The flushing effect, as already mentioned, increases the engine power significantly. While the illustrated auxiliary intake ports extend around the circumference of the cylinder, around the auxiliary intake ports 52 to connect to the main inlet duct 30, the auxiliary inlet ducts can extend axially to the cylinder from the Auxiliary openings extend directly to the crankcase chamber.

Patent claims:

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Claims (17)

Claims (l. ^ wide-stroke internal combustion engine with baffle piston, marked in combination a cylinder with a head (20) at one end, a piston (24) in the cylinder with alternating compression strokes towards the head and working strokes is movable away from this, Engine work cycles with an intake-exhaust phase during an end part of each power stroke and an initial part of the following compression stroke, diametrically opposed inlet and outlet openings (26 and 28, respectively) in the cylinder which are released by the piston during each working cycle phase in order to expel used combustion gas from the cylinder through the outlet openings and to allow combustible mixture to enter the cylinder through the inlet openings Guide wall (58) on the piston in an axial plane of the cylinder which extends between the inlet and outlet openings _{g to} divert to the cylinder head (20) combustible mixture that enters the cylinder through the mentioned inlet openings during each working cycle phase to remove residual gas flushing from the head of the cylinder, and means for directing additional combustible mixture into the area (50) behind the piston baffle (48) relative to the inlet openings during each work cycle phase in order to flush residual gas out of this area. - 13 - 709813/02 * 0 2. Combination according to claim 1, characterized in that additional mixture control elements said additional combustible Pass the mixture to and against the back of the piston baffle (48). 3. Combination according to claim 1, characterized in that the additional mixture guide elements the additional combustible mixture against the back of the piston guide wall of opposite sides of the cylinder. 4. Combination according to claim 1, characterized in that the additional mixture control elements are formed by auxiliary inlet openings in the cylinder wall, which are provided by the piston to be released during each working cycle phase, and means for the supply of combustible mixture to the mentioned Auxiliary openings. 5. Combination according to claim 4, characterized in that the mentioned auxiliary openings to the cylinder in the direction of mentioned level open to additional combustible mixture in the mentioned area to and against the back of the Guide piston baffle. 6. Combination according to claim 5, characterized in that the mentioned auxiliary opening by at least one narrow slot-like Auxiliary opening is formed, which is arranged in a plane which is parallel to the cylinder axis and to the the first mentioned level is inclined. - 14 - 709813/0280 7. Combination according to claim 6, characterized in that the auxiliary opening is adjacent by at least one auxiliary opening each end of the piston baffle is formed. 8. Combination according to claim 7, characterized in that the auxiliary opening is formed by two auxiliary openings, one of which is adjacent to each end of the piston guide wall. 9. Combination according to claim 1, characterized in that the engine has a crankcase chamber (22) and a Inlet channel communicates with this chamber, and first mentioned inlet openings through which combustible mixture passes from the mentioned chamber to the first mentioned inlet openings during each working stroke of the piston, and the additional mixture control element is formed by means, which the mentioned area with the crankcase chamber Connect during each work cycle phase. 10. Combination according to claim 9, characterized in that. the connecting means through auxiliary inlet openings in the Cylinder wall are formed, which are released by the piston during each working cycle phase and the additional Direct the combustible mixture against the back of the piston baffle. 11. Combination according to claim 10, characterized in that ■■■■■■■ - 15 - ■ 709813 / 0-280 the connecting means further comprise auxiliary inlet ducts, the one with the auxiliary openings and the crankcase chamber stay in contact. 12. Combination according to claim 11, characterized in that the engine has a body which has a cylinder part which includes a bore which is closed at one end by the cylinder head, and a Cylinder liner in the bore to form the mentioned cylinder, which mangen the inlet and outlet openings as well as the auxiliary openings, and which body is provided with a longitudinal recess in the wall of the bore, which on its inside through the Cylinder liner is closed and forms the inlet port, and a recess (72) in the wall of the bore closed on its inside by the cylinder liner is and forms the mentioned auxiliary intake port. 13. Combination according to claim 12, characterized in that the auxiliary opening by narrow slot-like auxiliary openings (52) adjacent to the ends of the piston guide wall (48) are formed in planes adjacent to the cylinder axis and are arranged obliquely to the first-mentioned plane, and the recess is formed by two circumferential recesses which extends from the intake port around the opposite sides of the cylinder liner to the auxiliary ports extend. 14. Method for increasing the performance of a two-stroke combustion - 16 - '709813/0280 A 522 engine with baffle piston, which is a cylinder with a head at one end thereof, further a piston which in the cylinder with alternating compression strokes is movable away from the cylinder head and working strokes, the engine work cycles an intake-exhaust phase during an end part of each working stroke and an initial part of the following compression stroke, diametrically opposite inlet and outlet ports are provided in the cylinder wall, which through the piston during each inlet-outlet phase are released to consume Push combustion gas out of the cylinder through the exhaust ports and into the combustible mixture Allow cylinders to enter through the intake ports, and a baffle on the piston for redirecting to the cylinder head the combustible mixture entering the cylinder through the intake ports during each intake-exhaust phase, to flush burned gases out of the cylinder head area, characterized in that additional combustible mixture in the area behind the Piston baffle, based on the inlet openings, is guided during each inlet-outlet phase. 15. The method according to claim 14, characterized in that directing the additional combustible mixture in the Way that this happens against the back of the piston baffle is judged. 16. The method according to claim 14, characterized in that the passing of additional combustible mixture against the Back of the piston baffle from opposite sides - 17 - 709813/0280 of the cylinder happens. 17. The method according to claim 14, characterized in that the aforementioned conduction occurs in that combustible mixture from the engine crankcase chamber to opposite Sides of the cylinder is guided and then through the wall of the cylinder adjacent the ends of the piston baffle in the mentioned area in the direction of the back of the piston guide wall and obliquely to this, so that the mixture the Rear side of the guide wall acted upon. For: Mr. John C. Perry PATENTANWÄLTE ING. S. STAEQtR. IF. t «r. nat. - 18 - 709813/0280