NO314553B1 - Device for 4-stroke internal combustion engine - Google Patents

Description

The present invention relates to a device for a 4-stroke internal combustion engine as stated in the introduction to the patent claim.

An internal combustion engine of the aforementioned type is a thermal power machine where the combustion of a fuel mixture takes place in a cylinder. The heat energy is converted into mechanical work by the pressure of the combustion gas acting on a moving piston in the cylinder - The piston has a rectilinear alternating movement, which is transferred to a rotating movement by means of a crank mechanism. The shaft in the crank mechanism is also the engine's energy outlet.

The processes inside the cylinder take place in series, which include air and fuel intake, compression, combustion, expansion and expulsion of combustion gas. Each piston stroke in the series represents a measure. Internal combustion engines are divided according to stroke type, namely 2-stroke and 4-stroke engines. As mentioned, the invention relates to 4-stroke engines.

For intake and exhaust respectively of fuel mixture and combustion gas in 4-stroke engines, there are valve-controlled top lasered or side-located intake and exhaust ports or openings in the cylinder.

Intake valves and exhaust valves are controlled with a valve control. Such valve controls include camshafts that act directly or indirectly (lift rods) on the valves. The camshaft(s) are driven from the engine shaft.

There are a number of advanced valve controls, but what these have in common is that they require a relatively large number of components and that the valves are exposed to great stress with associated wear and tear. The space in a cylinder also sets limits for the size of the valve ports, as, for example, with top lasered valves, you only have a limited area (the cylinder surface) at your disposal. Side-placed valves provide better space, but common to all valve arrangements is that camshafts, valve springs, valve guides etc take up space and are subject to internal friction. The valve springs in particular act as rev limiters. Heat generation and vibrations are also a problem.

From US 4331118, a 4-stroke engine is known with a non-return valve in the form of a reed valve in an intake opening which is arranged in the cylinder wall and alternately covered by the piston.

From EP 382063 Al, a 2-stroke engine is known where a rotary valve is arranged in the outlet opening in addition to the usual outlet opening in the cylinder wall. The rotary valve is arranged under the piston ring area of the piston when the piston is at the top dead center of the piston.

From DE 4118254 Al the use of a rotary valve in connection with a 2-stroke engine is known.

The purpose of the present invention is to provide a 4-stroke engine which is lighter (less weight), can be made smaller (more compact) and can be produced more cheaply than previously known 4-stroke engines.

According to the invention, a device as defined in the patent claim is therefore proposed.

It should be mentioned that piston-operated gates are known for 2-stroke engines and it is likewise known to use non-return valves, also in the form of leaf valves, in 2-stroke engines, in the intake/flushing system. However, as mentioned, these known non-return valves are included in the flushing system which is typical precisely for 2-stroke engines, where the crankcase is used as a mixing chamber for air and fuel before this enters the cylinder space above the piston, as the non-return valve then closes against the carburettor.

The invention provides a 4-stroke engine with fewer mechanically driven parts. The engine will therefore work with less friction (energy consumption) than the known 4-stroke engines. Fewer mechanically driven parts and less friction result in higher power and lower fuel consumption.

Special features of the invention and its advantages will be elucidated in more detail below, in connection with a description of an embodiment of the invention, with reference to the drawings where Figure la-e schematically shows a device according to the invention and its mode of operation, and

Figure 2 shows a section of the upper engine area, on a larger scale.

The purely schematic figures only show the essential parts for understanding the invention. Details not shown are well known to the person skilled in the art and do not differ from constructive details used for 4-stroke internal combustion engines.

Figure 1 shows a 4-stroke internal combustion engine which includes a cylinder 1, a crankcase 2 and a cylinder head 3. 1 cylinder 1 is fitted with a reciprocating piston 4, which is connected by a crank rod 5 to the crankshaft 6 stored in the crankcase 2, in the drawing indicated by a circle. An intake for fuel mixture is indicated at 7, and an exhaust valve is indicated at 8.

In the cylinder head 3, an opening 9 for the placement of a spark plug/glowing element (not shown) is only indicated here.

The internal combustion engine shown works in a known way for a 4-stroke engine: In an intake stroke

the crank mechanism pulls the piston from top to bottom position. Air and fuel are then sucked in through the intake. In the next stroke, the compression stroke, the crank mechanism pushes the piston from bottom to top position. The intake valve is closed and the fuel mixture is compressed. In the third stroke, the working stroke, the ignited fuel mixture will expand and push the piston from top position to bottom position. Just before the end of the stroke, the exhaust valve opens. In the fourth stroke, the exhaust stroke, the crank mechanism moves the piston from the bottom position to the top position. The exhaust valve is open. The combustion gas is then pushed out of the cylinder. This is followed by a new intake stroke, etc.

According to the invention, the engine has a new and advantageous intake system 7.

An opening or port 10 is formed in the cylinder wall of cylinder 1, see in particular figure 2. This port 10 is connected to a carburettor (not shown) through a channel 11 only indicated here. In the channel/port 10/11, a non-return valve 12 is arranged, in the form of two blade tongues 13 and 14, which cooperates with a valve seat 15.

The exhaust valve 8 is in the design example in the form of a rotary valve, with a rotary body 16 which has a diametrical channel 17, which can be brought flush with an exhaust port 18 in the cylinder 1 and an exhaust line 19. The rotary body 16 rotates with the crankshaft by means of a timing belt shown, with a transmission ratio of 1:4. The rotary valve, i.e. the rotary body 16, thus runs at half the speed of a normal camshaft. The advantage of such a rotary valve is, among other things, a. in the reduced speed, with less tension in and longer service life for the toothed belt.

Such rotary valves are known to be used in engines and the rotary valve in itself therefore does not represent anything new. However, its location in the cylinder wall, below the piston's sealing rings 20 in the upper position of the piston 4, entails a significant advantage. The final compression and explosion (combustion) then takes place namely against the cylinder head 3 and against the piston 4, and not directly against the rotary valve 9,16. The intake valve 7 will not be affected either, as it is located in the cylinder wall, below the piston ring area 12 in the beginning working stroke.

The sealing rings 20, i.e. the piston springs and the oil spring, are locked (not shown) so that the spring openings do not enter the ports 10,18 when the piston 4 passes through them.

The operation of the new device according to the invention will now be explained in more detail, with reference to the figures.

In figure la, the piston 4 is shown on its way down in the working stroke. Exhaust valve 8 is closed. The intake valve 7 is also closed, as the blade tongues 13,14 are in contact with the valve seat 15 and the piston also covers the intake port 10. This prevents intake of oil from the crankcase.

In Figure 1b, the piston 4 is on its way up the exhaust stroke, after passing bottom dead center. Exhaust valve 8 is open. The intake valve 7 is still closed.

In Figure 1c, the piston 4 is on its way down in the intake stroke. Both exhaust valve 8 and intake valve 7 are closed. In figure Id, the piston 4 is shown at bottom dead center, at the end of the intake stroke. The intake valve 7 is open, it opens as soon as the negative pressure in the cylinder space takes effect, when the piston 4 begins to cover the port 10, as the blade tongues then swing out from the seat 15. Fuel mixture flows into the cylinder 1 above the piston 4.

In figure le, the piston 4 has reached top dead center in the compression stroke. The intake valve is closed as a result of the pressure rise and the piston 4 also covers the port 10. The exhaust valve 8 is closed. After the piston has passed top dead center, ignition is initiated in a known manner and the piston begins its working stroke (figure la).

It has surprisingly turned out that the relatively late opening of the intake 7 does not represent any disadvantage. It is also easily compensated for by the fact that the placement of the intake port 10 in the cylinder wall now allows for a larger port opening (cross-sectional area), with an increased degree of filling. It is also conceivable to have more than one port 10 in the cylinder wall. The non-return valve 12 works quickly and independently and requires no mechanical or hydraulic valve control.

It is not shown, but the piston-controlled intake opening can also be used without a membrane or non-return valve, then with a compressor which ensures that there is an overpressure in the intake channel.

The non-return valve must be placed in the intake duct as close to the piston as possible, to avoid loss of power.

The intake system has no influence on electronic control units used in modern engines, such as lambda probe catalysts.

In sum, a lighter, less space-consuming and cheaper 4-stroke engine is achieved. The engine's combustion is not limited as in a normal top-ventilated engine, where the valve sizes will be limited by the diameter in the cylinder. The result is better combustion/power and cleaner exhaust gas.

As material in the non-return valve, i.e. in the blade tongues 13,14, commonly known metal materials suitable for such valve environments can for example be used. One possible material is a Kevlar-based material.

Claims (1)

Device for a 4-stroke internal combustion engine with a linear reciprocating piston (4) in a cylinder with a cylinder wall, with valve-controlled intake and exhaust openings (7,8) in the cylinder (1) for a fuel mixture and combustion gas respectively, the intake opening (10 ) is arranged in the cylinder wall so that it is alternately covered and uncovered by the reciprocating piston (4), and in the said intake opening (10) there is arranged a reed valve (12) which closes for intake in case of overpressure and opens for intake in negative pressure in the cylinder (1), characterized in that an ejection valve is arranged in the ejection opening (8) in the form of a rotary valve (8,16) known per se arranged under a piston ring area (20) on the piston (4) when the piston (4) ) is at the top dead center of the piston and so that it will be under said piston ring area (20) in the ignition phase of the fuel mixture.