CZ278690B6 - Cylinder block of two-stroke internal combustion engine - Google Patents

Abstract

A reed valve is pivotally secured to the inner walls of the gas compression chamber for passing fuel/air mixtures into the gas compression chamber upon depressuring. A cylinder closure is positioned at the upper end of the cylinder defining the upper end of the firing chamber, being provided with an exhaust gas valve adapted for cyclic opening and closing to alternatively permit the removal of exhaust gases from the firing chamber and the pressuring to the fresh fuel/air mixtures in the firing chamber. A fuel ignition device ignites a compressed fuel/air mixture in the firing chamber. At least a portion of the elongated cylinder inner walls extends downwardly into the gas compression chamber, adapted to house at least a portion of the piston during the full downstroke of the piston. The upper portion of the crankcase housing has inwardly sloping walls to define a converging gas space in the upper portion of the gas compression chamber annularly about the downwardly extending cylinder portion.

Description

(57)

The elongated portion (44) of the cylinder is extended into the pump chamber (26). The walls of the upper portion (36) of the crankcase (2) taper to the extended portion (44) of the cylinder toward the inlet ducts (22).

CZ 278 690 B6

Two-stroke internal combustion engine cylinder block

Technical field

The invention relates generally to internal combustion engines, in particular to two-stroke internal combustion engines.

BACKGROUND OF THE INVENTION

Two-stroke water-cooled internal combustion engines (U.S. Pat. No. 1,292,322) are known which have a double cylindrical wall and are provided with a rotatably arranged gas inlet valve member and are controlled by a cam with a cam mechanism consisting mainly of a spring and a rocker arm. The exhaust gas is provided by another cam-controlled cylindrical member displaceably mounted on the pin to which the piston rod is connected by means of a transmission device.

Further, an internal combustion engine (US Patent No. 1,540,286) is known which has an exhaust valve disposed at the top of the cylinder. The engine thus has a rotationally arranged gas inlet device and a suction slide arranged in the crankcase, which is connected to the crankcase pump space.

Also known is a two-stroke internal combustion engine (US Patent 2,337,245) having a set of gas inlets at one end of the cylinder and a set of gas outlets at the other end of the cylinder. Each set of gas inlets or outlets is opened and closed by means of a separate reciprocating piston arranged in the cylinder.

Another known internal combustion engine (U.S. Pat. No. 2,516,708) is a two-stroke single-action internal combustion engine having an air chamber attached to the inlet end of the cylinder.

Another known internal combustion engine arrangement is a two-stroke internal combustion engine (U.S. Pat. No. 2,572,768), the inlets of which enable swirling movement and which is provided with tangential gas injection.

Also known is an internal combustion engine (US patent 4,004,557), whose piston-cylinder assembly has a cup-like extension at the top and which is provided with a plurality of vertical through-pass channels or a crankcase and a cylinder.

However, prior art engines have the disadvantage of insufficient flushing of the combustion chamber of the cylinder and hence of low efficiency and high fuel consumption.

SUMMARY OF THE INVENTION

These disadvantages are overcome by an engine according to the invention, whose cylinder block consists of an elongated cylinder whose inner walls are substantially vertical. The extended combustion chamber houses a piston. The engine is provided at the bottom of the combustion chamber with gas inlet ducts and a crankcase having a pump chamber as well as a valve device, in particular a suction slide for controlling the flow of fuel-air mixture into the pump chamber.

-1GB 278690 B6

At the top of the combustion chamber there is provided an exhaust device, in particular exhaust valves and exhaust pipes, as well as an ignition device, in particular a spark plug for igniting the compressed fuel-air mixture in the combustion chamber. The main claim is characterized in that the inner walls of the elongate part of the cylinder are extended into the pump chamber and in this part the piston is located at its bottom dead center, the upper part of the crankcase having inwardly converging walls defining a tapering space at the top of the pump chamber. a space that annularly surrounds the lower elongate portion of the cylinder. This space in the upper part of the pump space is connected to the combustion chamber by inlet ducts. The piston assembly is movably coupled to the exhaust assembly. According to a further feature of the invention, the inlet valve is rotatably mounted on the inner wall of the pump chamber. The cylinder head formed at the upper end of the cylinder and defining the upper end of the combustion chamber is provided with an exhaust valve device, in particular an exhaust valve for cyclically opening and closing.

According to another claim, the upper end of the cylinder is provided with a second cylinder, which consists of a chamber and houses a second piston. The exhaust chamber is connected to the upper end of the combustion chamber. The second cylinder is provided at its lower end with exhaust openings cyclically opened and closed by a second piston. The second piston is in kinematic relationship with the piston.

According to the last claim of the invention, the second cylinder has a larger diameter than the combustion chamber.

An engine with a block constructed in accordance with the invention has the advantage of effectively flushing the combustion chamber. This purging occurs with the gas compressed in the pump chamber as the piston moves to the bottom dead center. At the bottom dead center, the piston exposes the inlet ducts so that the compressed gas passes through the narrowing gas space and the inlet ducts into the combustion chamber from where it expels the flue gases of the previous charge.

Description of the drawings

The invention is illustrated by way of example with reference to the accompanying drawings, in which: FIG. 1 is a vertical cross-sectional view of a motor according to the invention, provided with one cylinder; FIG. 2 is a horizontal cross-section 2 ' Fig. 3, Fig. 4 is a vertical sectional view of another embodiment of an internal combustion engine according to the invention provided with a single cylinder.

Fig. 5 - horizontal section 5 '- 5' according to Fig. 4, Fig. 6 - horizontal section 6 '- 6' according to Fig. 4.

-2GB 278690 B6

Exemplary embodiment

The engine according to the invention is shown in the first embodiment in Figs. 1, 2 and 3 and arranged as a single cylinder, which means that in addition to the single cylinder arrangement, the engine can be made with multiple cylinders, all of the engine cylinders according to the invention being designed as described and shown. The engine according to the invention can be used in a motorcycle, boat, electric generators and the like.

As can be seen from the drawing, the engine is air-cooled, but in another embodiment, it can also be cooled by water or oil as desired, and a cooling jacket is formed around the cylinder.

The engine 1 comprises a crankcase 2 which is provided with suitable bearing means 32, furthermore a crankshaft 43, as well as a connecting rod 40, which is rotatably mounted in the piston 20 by means of a piston pin 46.

The pump chamber 26 is arranged in the upper part 36 of the crankcase 2, which is in alternation with the gas inlet 45. The inlet 45 is opened and closed by means of a suction slide 4, which is arranged in a recess 47 in the inner wall of the crankcase 2. The suction slide 4 is rotatably mounted on the valve pin 38 so that it can deflect inside the pump chamber 26 and allow gas to flow The suction spool 4 is pressed into the inlet 45 while compressing the gas in the pumping chamber 26 while abutting the recess 47, thereby ensuring that the suction spool is seated in its closed position. position. This prevents gas leakage from chamber 26 to inlet 45 when the gas in the pump chamber 26 is compressed. The suction slide 4 can also be arranged in another way, for example as an elongated valve of known type.

The cylinder 16 is provided with an elongated hollow cylindrical portion connected to the elongated combustion chamber 17, wherein the piston 20 is arranged in the combustion chamber 17 to move vertically in a reciprocating motion.

The extended portion 44 of the cylinder 16 is recessed into the pump chamber 26 and accommodates a portion of the piston 20 at its bottom dead center. The length of the elongated portion of the cylinder 16 is equal, preferably 0.1 to 2 times the height h of the piston 20./ in particular, 0.4 to 1.5 times this height h. of the cylinder 44.

The cylinder 16 is mounted on the crankcase 2 as shown in FIG. 1. However, the cylinder 16 can be made in one piece with the crankcase 2.

A series of inlet ducts 22 are provided in the wall of the cylinder 16 which, when the piston is positioned at the bottom dead center, connects the combustion chamber 17 to the pump chamber 26. The way in which these ducts 22 are opened and closed is described below. The number and location of the channels 22 may vary, but in particular the channels 22 are arranged around the circumferential wall of the elongated portion 44 of the cylinder 16. As shown in Fig. 2. The number and size of the inlet channels 22 are chosen primarily to achieve maximum flow but not to impair the strength of the walls of the cylinder or its pro

Typically, two to 20 of these inlet channels 22 are used, with a number of between 6 and 10 being preferred. If a plurality of these channels are used, each inlet channel 22 has a horizontal cross-section the size of which is 2, lies between 1 and 10%, in particular between 3 and 8% of the total cross-section of the circular profile of the cylinder 16.

A plate-shaped head 14 is provided at the upper end of the cylinder 16, which defines an upper end of the combustion chamber 17. The cylinder head 14 can be detachably arranged by a flange 5 formed at the upper edge of the wall of the cylinder 16. screws (not shown). On the head 14 there is arranged an exhaust pipe 70 and an exhaust valve 7, whose stem 6 extends through the head 14. This exhaust valve 7 is arranged to open and close the exhaust outlet to the exhaust pipe 70 and is therefore provided with a spring 2 / mounted on the stem 6 above the plate head 14 and is further connected to a cam 8 which rotates and is mounted on a camshaft 10, in which rotation the cam 8 pushes the shaft 6 and thereby moves the valve 7. The valve 7 thus moves vertically up and down thereby closing or opening the exhaust outlet.

The number and location of the exhaust valves 7 may vary, typically from 1 to 4 valves 7 are used for each engine 1, these exhaust valves 7 being arranged circularly at the upper end of the combustion chamber 17 to allow rapid movement of exhaust gases from the combustion chamber 17; to prevent the back-mixing and uptake of the exhaust gases, and also to reduce the efficiency of the engine.

A conventional spark plug 12 or other ignition device is disposed at the top of the cylinder 16. The spark plug 12 may also be located in the head 14 along the longitudinal axis of the combustion chamber 17.

In its closed position, each exhaust valve 7 is firmly seated in the seat in the recess of the inner wall of the head 14 to prevent gas from entering or leaving the combustion chamber 17.

At the upper end of the crankcase 2 in accordance with the illustrated embodiment of the engine according to the invention, the walls of the crankcase 2 are arranged in a tapered shape and thereby define a tapered gas space 30 which is arranged in this manner to achieve a fast and efficient filling of the combustion chamber 17. Each of the inlet ducts 22 is arranged in a cross-section of the wall of the combustion chamber 17 and the elongated portion 44 in a circle about a longitudinal axis, the axes of the inlet ducts 22 being at an angle α with the vertical. a value between 10 and 60 °, in particular between 30 and 50 °. This combination of the tapered gas space 30 and the inclined inlet ducts 22 allows a fast and efficient filling of the combustion space 17.

The length of the combustion chamber 17 is adjusted so that the piston 20 at its top dead center does not come into contact with the head 14 or the plug 12 or the exhaust valve 7. At its bottom dead center the piston 20 exposes the inlet ducts 22 thereby allowing connection between the pump chamber 26 and a combustion chamber 17. The lower, extended portion 44 of the cylinder 16 is adapted such that the piston 20, at its lower dead center, is received in its extended portion 44 throughout its length.

-4GB 278690 B6

In the usual two-stroke engine operation, air and fuel, which may be premixed in the desired ratio by conventional means such as carburettor, injection or supercharging, are fed to the pump chamber 26 via the suction slide 4 when the piston 20 moves upward to the top dead center and closes the inlet ducts 22. In this way, fresh gas is sucked in by the vacuum in the pump chamber 26 through the inlet 45. When moving to the bottom dead center, the piston 20 compresses the gas in the pump chamber 26 with the suction slide 4 closed. it exposes the inlet ducts 22 so that the compressed gas is forced out through the tapered gas space 30 and the inlet ducts 22 into the combustion chamber 17 at which the pressure is currently less by the previous charge being discharged by the exhaust valve 7. closes after fresh fuel mixture and air was introduced into the combustion chamber 17 to prevent leakage of fresh air-gas mixture when compressed by moving the piston to the top dead center. If desired, the exhaust valve 7 can be opened for a certain period of time by moving the piston upwards to allow the exhaust gas to be forced out of the combustion chamber 17 through the fresh feed. At a suitable moment the piston 20 moves towards the top dead center. of air and combustion of this mixture exerts a force on the piston 20 to compress the piston 20 downwards. At the appropriate moment of the downward movement of the piston, the exhaust valve 7 opens to allow exhaust gas to be discharged from the combustion chamber 12.

Figures 4, 5 and 6 show another arrangement of the engine according to the invention. Also in this arrangement, the engine may have one cylinder, as shown, or multiple cylinders. All these rollers are identical in principle to the design according to the invention. The engine of the invention with a particularly lightweight construction can be used to drive motorcycles, boats, electric generators and the like. The engine arrangement of the invention is also air cooled, but can be water cooled when using a cooling jacket on the cylinder 116.

The engine 101 of FIG. 4 comprises a crankcase 102 which is connected to the crankshaft 143, connecting rod 140 and piston 120 by means of bearing 132. The connecting rod 140 and piston 120 are rotatably connected to each other by means of a piston pin 146.

A pump chamber 126 is provided in the upper portion 136 of the crankcase 102, which is alternately connected to the gas inlet 145. The inlet 145 is opened and closed by an inlet valve 104 disposed in a recess 147 in the inner wall of the crankcase 102. The suction slide 104 is rotatably mounted on the valve pin so that it can tilt inwardly into the pump space 126 thereby allowing or restricting gas flow from the depending on whether the gas pressure in the pump chamber 126 is greater than or less than the gas pressure in the inlet 145. During the increased pressure in the pump chamber 126, the suction slide 104 is folded into the recess 147, thereby preventing leakage of gases from the pump chamber. space 126 to the inlet 145 as will be described in detail below. The suction spool 104 can also be configured as an elongated cylindrical valve and positioned to meet the task described above, ie to prevent gas leakage and allow gas to enter the pump chamber 126.

-5GB 278690 B6

The cylinder 116 comprises an elongated portion 144 which is cylindrical in shape and hollow and constitutes an extension of the combustion chamber 117. In this elongated portion 144 the piston 120 is located at its bottom dead center of its vertical reciprocating motion in the combustion chamber 117. pump length 126, the length of the elongated portion 144 is equal to 0.1 to 2 times the height h of the piston 120, but in particular 0.4 to 1.5 times this height h. These dimensions are most preferred, but other extended lengths may be used The cylinder 116 is rigidly connected to the crankcase 102 as shown in Fig. 4, wherein the cylinder 116 and the crankcase 102 can be formed in one piece.

At the bottom of the cylinder 116 and at the top of the walls of the elongated portion 144, a series of inlet ducts 122 are provided to connect between the pump chamber 126 and the combustion chamber 117. The way the ducts 122 are opened and closed is described below. The number and position of the inlet ducts 122 at the periphery of the cylinder 116 may be variable, but most preferably the ducts 122 are disposed along the periphery of the elongated portion 144 as shown in FIG. 5. The number and size of these inlet ducts 122 are selected to achieve maximum flow The largest cross-section is determined by the requirement to maintain the wall structure of the cylinder 116 and the elongated portion 144. Generally, two to twenty of these inlet 122, in particular six to ten, are used. When using a plurality of inlet ducts 122, each inlet duct 122 has a horizontal cross-sectional area of 1 to 10%, in particular 3 to 8%, of the total cross section of the circular profile of the cylinder wall 116. % or more, in particular between 25 and 45% of the total cross section of the circular profile of the wall of the cylinder 116.

At the upper end of the crankcase 102, in accordance with the arrangement of FIG. 4, the crankcase wall is tapered inwardly and thus delimits the tapered gas space 130 of the pump space 126 in its portion around the extended portion 144 of the cylinder 116. Each of these inlet ducts 122 is preferably disposed in a cross-section, i.e. in the direction of gas flow, inclined relative to a vertical center axis, the inlet ducts 122, respectively. they form an angle α with the vertical axis within the wall of the combustion chamber 117. This angle α is between 10 and 60 °, in particular between 30 and 50 °. This combination of inclination of the inlet ducts 122 and the narrowing gas space 130 allows a very fast and efficient filling of the combustion chamber 117.

At the upper end of cylinder 116 there is arranged a spark plug 112 or other ignition device to ignite the air / fuel mixture in the combustion chamber 117. At the upper end of cylinder 116 there is a piston device consisting of a second cylinder 156 receiving the second piston 150, the second cam 160 and the exhaust ports 115. One or more exhaust ports 115 are disposed at the bottom of the second cylinder 156 and allow gas to flow from the upper end of the combustion chamber 117 to the exhaust manifold or other conventional exhaust gas exhaust manifold from the cylinder 116 and the second cylinder. 156.

-6GB 278690 B6

The second piston 150 is arranged for vertical reciprocating movement in the exhaust chamber 118 defined by the second cylinder 156. The movement of the second piston 150 is controlled by a second cam 160 which moves the second connecting rod 162 on which the second piston is rotatably supported by the second piston pin 163. the second piston is provided to open and close the exhaust ports 115.

The number, size and arrangement of the exhaust ports 115, as with the inlet ducts 122, are variable and vary from one to twenty, the cross-section preferably being such that each of the exhaust ports 115 has a cross-section between 1 to 10% roll 156 in a direction perpendicular to the longitudinal axis of said second roll 156, wherein the total cross-section of the exhaust ports 115 is between 10 to 60% or more of the total cross-section of the circular profile of the second roll 156.

The upper, second cylinder 156 defines a cylindrical exhaust chamber 118 having a diameter in particular 10-150% larger, but preferably 30-80% larger than the diameter of the combustion chamber 117. Such an arrangement of the exhaust ports 115 and the second piston 150 allows efficient discharge. flue gas from the combustion chamber 117 and causes the engine of the invention to operate at a high number of revolutions, i.e. a large number of strokes per minute, with smooth running and limited turbulence.

The length of the combustion chamber 117 and the location of the spark plug 112 is such that the piston 120, at its top dead center, not shown in the drawing, does not come into contact with the spark plug 112 or part of the second cylinder 156 and its second piston 150. the piston 120 exposes the inlet ducts 122, thereby allowing a connection between the pump space 126 and the combustion chamber 117 for gas flow. The elongated portion 144 of the cylinder 116 is of sufficient length to accommodate the piston 120 at its bottom dead center. The piston 120 is thus fully positioned within the extension of the combustion chamber 117 formed by the inner walls of the extension portion 144 of the cylinder 116. The second piston 150 at its top dead center fully exposes the exhaust ports 115 thereby allowing the exhaust gas to flow out of the combustion chamber 117. 150 completely obstructs exhaust ports 115, thereby preventing gas from entering the combustion chamber 117 or leaking gas-air mixture from this combustion chamber 117 during compression and ignition, as described in more detail below.

In the usual two-stroke operation, the air-fuel mixture, which may be preformed in a suitable proportion by conventional means, such as a carburetor, injection or supercharger, is fed to the pump chamber 126 via the suction slide 104 while moving the piston 120 towards upper dead center after closing In the downward movement of the piston 120, the piston 120 compresses the gas accumulated in the pump compartment 126 while the inlet valve 104 is closed. part of the casing of the piston 120 opens the inlet passages 122, thereby allowing compressed gas to flow through the tapered gas space 130 and the inlet passages 122 into the combustion chamber 117 in which the pressure has already been reduced when the piston 120 moves downwards and p 150 to its top dead center. The exhaust ports 115 are closed when the second piston 150 is moved downwardly, wherein

278690 B6, a fresh fuel / air mixture coming into the combustion chamber 117 is compressed while the piston 120 is moved to the top dead center, and if necessary, the timing of the movement of the second piston 150 at its bottom dead center can be determined so that the exhaust ports 115 are still open for a certain period of movement of the piston 120 towards the top dead center to allow the remaining flue gas to be discharged from the combustion chamber 117. At the selected moment of movement of the piston 120 to the top dead center, while the exhaust ports 115 are closed, the spark plug 112 ignites the fuel mixture; Air and combustion gases exert a force on the piston 120 downwardly, whereupon the exhaust ports 115 are re-opened by moving the second piston 150 towards its top dead center so that flue gas is allowed to escape from the combustion chamber 117. Timing and operation of the second piston 150 and piston 120, as well as their cams, and the spark plugs 112 are conventional it does not need to be described in more detail.

PATENT CLAIMS

Claims (4)

1. A cylinder block of a two-stroke internal combustion engine having inlet portions at the bottom and a crankcase having a pump chamber with a valve device, in particular a suction spool, a piston in the combustion chamber and an exhaust device in its upper part; in particular exhaust valves and exhaust pipes and ignition devices, in particular a spark plug, which are operated by a connecting rod or a crankshaft, characterized in that the cylinder extension (44, 144) is extended into the pump chamber (26, 126), the upper walls portions (36, 136) of the crankcase (2) taper to the elongated portion (44, 144) of the cylinder toward the inlet passages (22, 122). Cylinder block according to claim 1, characterized in that a suction slide (4, 104) is rotatably mounted on the inner wall of the pump chamber (26, 126) and an exhaust valve device is arranged on the cylinder head (14, 116) , in particular an exhaust valve (7) for cyclic opening and closing. Cylinder block according to claim 1, characterized in that the upper end of the cylinder (116) is provided with a second cylinder (156) which has at its lower end exhaust ports (115) and consists of an exhaust chamber (118) which is connected to the upper end of the combustion chamber (117) and in the second cylinder (156) there is a second piston (150) which is in kinematic coupling with the piston (120). Cylinder block according to claim 3, characterized in that the second cylinder (156) has a larger diameter than the combustion chamber (117).