EP0754268B1 - Two-stroke diesel engine with a spiral air intake duct - Google Patents

Description

The principle of the invention relates to a diesel engine with two-stroke with volute air intake channel, and more particularly to a diesel engine which has a channel air intake which has a spiral shape and is arranged on part of the circumference of the wall of the cylinder, the intake channel which is arranged at the location of the bottom dead center of the piston being connected to the cylinder by channels of transfer which are separated by walls in the shape of blades.

Generally speaking, two-stroke diesel engines operate on the principle that the air intake, which is the oxidizer, is constant, and the fuel injection is variable. In the case of a vehicle for example, the action on the accelerator pedal adjusts the amount of fuel which is distributed.

The power of two-stroke diesel engines is dependent on the quality of the oxidizer-fuel mixture, the optimal power being obtained when each molecule of fuel can ally to an oxidizer molecule. The mixing of the oxidizer in the cylinder is essential to ensure that an optimal proportion of fuel molecules can ally with molecules of oxidizer. Insufficient mixing of the oxidizer results in a lack of homogeneity of the oxidizer-fuel mixture which reflected in the fact that a certain proportion of the fuel is not burnt and by the fact that the engine whose combustion is incomplete, works with a large excess of oxidizer.

All known two-stroke diesel engines operate with insufficient mixing of the oxidizer and this drawback essential causes reductions in power and efficiency important.

Most known two-stroke diesel engines have valve-light combinations, for example, the lights being intended for the intake of oxidizer and the valves to the exhaust of the burnt gases or vice versa.

An embodiment known as the Schnurle principle has several lights which are arranged in a way symmetrical on each side of the cylinder. This form of execution has allowed to bring some increase in brewing and by therefore power and efficiency. However, the arrival symmetrical oxidant in the cylinder does not create sufficient mixing which again results in a strong loss of power and efficiency relative to power and optimal performance.

Depending on the aforementioned drawbacks of diesel engines two known times and depending on environmental issues and of energy resources, it is conceivable that these motors, which are currently used mainly based on their reliability and low fuel cost, are gradually prohibited if significant improvements are not made.

The aims of the present invention therefore consist in remedying to the aforementioned drawbacks of known diesel engines.

The objects are achieved according to the principle of the invention described in claim 1.

The two-stroke diesel engine with volute air intake channel, according to the principle of the invention, comprises an air intake channel which is arranged over a large part of the circumference of the cylinder wall and which is connected to the cylinder by transfer channels which are separated from each other by vanes. The air is propelled into the volute intake channel by a turbo-compressor for example. The vanes separating the transfer channels are arranged at angles to the axis of the cylinder. In this way the air admitted when the piston is in bottom dead center, is propelled into the cylinder with a very strong vortex movement. This circular vortex movement is supplemented by an upward movement caused by the fact that the transfer channels gradually present an upward angle of the cylinder. In fact, the first transfer channel is arranged so that the air is propelled horizontally into the cylinder and the last channel is arranged so that the air is propelled at an angle of 45 ° upwards by example. The strong vortex and circular movement and the progressive upward mixing of the air thus created in the cylinder are further accentuated by the fact that the volume of air admitted into the cylinder becomes progressively concentrated, by the displacement of the piston towards the high, in the combustion chamber whose volume is much smaller than the cylinder.
The very strong mixing of the air thus created makes it possible to guarantee a very significant improvement in the homogeneity of the oxidizer-fuel mixture which makes it possible to approach optimum power and efficiency.

The very significant improvement in power and efficiency obtained by the principle of the invention allows, at power -equal supply compared to known two-stroke diesel engines, significantly reduce consumption and pollution. AT equal consumption, the principle of the invention allows significantly increase engine power while avoiding, by complete combustion, that this increase in power does result in increased pollution.

The accompanying drawings illustrate schematically and by way of of example the principles of the invention.

Figures 1 and 2 are sectional views, respectively vertical and horizontal, cylinder and piston of an engine two-stroke diesel with an air intake channel in volute.

Figures 3, 4 and 5 are vertical section views of transfer channels, respectively at the start, in a portion intermediate and at the end of the air intake channel.

Figures 6 and 7 are sectional views, respectively vertical and horizontal, of an embodiment of a cylinder comprising an exhaust channel with closure device.

Figures 8 and 9 are sectional views, respectively vertical and horizontal, of a cylinder with a channel volute air intake and an exhaust channel which also has a scroll shape.

Referring first to Figures 1 and 2, the wall of a cylinder 2 has an air intake channel 1 which has a scroll shape. The air intake channel 1 is arranged on the much of the circumference of the cylinder wall 2. The air intake channel 1 is connected to the inside of cylinder 2 by transfer channels, for example 3, 4 and 5. The transfer channels are separated from each other by vanes, by example vanes 6, 7 and 8. The vanes are arranged in a angle with respect to the central axis of the cylinder. The canals of transfer are arranged at the bottom dead center of a piston 9, so that they are open when the piston found in bottom dead center. The head of the piston 9 has a combustion chamber 10 in which the fuel-oxidant mixture takes place when the piston is in neutral high and when the fuel injector 11 injects the fuel. According to the principle of two-stroke diesel engines, combustion of the fuel-oxidant mixture occurs through self-ignition which is caused by the combined effects of the very strong pressure and temperature in the combustion chamber. According to the principle of the invention, air, or oxidizer, is powered in the intake channel 1 by a turbo-compressor, for example. The air thus propelled into the intake channel 1, is propelled into cylinder 2 by the transfer channels. The vanes that separate the transfer channels are arranged in a angle relative to the central axis of the cylinder so that the air is propelled inside the cylinder with a very strong vortex movement around the cylinder axis. Air or oxidizer is allowed when the piston discovers the transfer. The vortex movement of air or oxidizer is still greatly increased during the rise of the piston, due the difference in volume between the cylinder and the combustion. The intake channel 1 has a volute shape and the intake channel becomes progressively smaller by so that the air pressure propelled by the channels which are sufficient at the end of the air intake channel.

Referring to Figures 1 to 5, Figure 3 shows a channel transfer 3 which is arranged at the start of the intake channel 1. The upper and lower faces of the transfer channel 3 are arranged in the horizontal plane and in this case the air is propelled horizontally in the cylinder. Figure 4 shows a transfer channel 4 which is arranged in a portion intermediate of the intake channel 1. The upper faces and bottom of transfer channel 4 are arranged at an angle upwards from the horizontal plane. Figure 5 shows a transfer channel 5 which is arranged at the end of the channel 1. The upper and lower sides of the transfer 5 are arranged with a strong upward angle by compared to the horizontal plane. In summary, the angle of the faces upper and lower transfer channels increase gradually from 0 ° for the first channel to 45 °, by example, for the last channel. In this way, in addition to the vortex movement around the cylinder axis, the air is gradually propelled up the cylinder which further strengthens the vortex movement.

The very strong vortex movement is amplified in the combustion chamber when the piston is in neutral high, and this strong vortex movement guarantees a optimal fuel-oxidizer mixture when fuel is distributed. This optimal mixture guarantees combustion complete which allows to obtain a very important improved performance which also results in significant pollution reduction.

As shown in Figures 1 to 5, the air intake channel 1 has a volute shape, or a spiral shape, the intake channel being progressively arranged downward in depending on the angle of the transfer channels.

Figures 1 and 2 do not show exhaust. In that case the exhaust is conventional and can consist of a valve arranged in the upper part of the cylinder by example.

Figures 6 and 7 show an embodiment of a cylinder 14 which also includes an injector 11, with a piston 9 which has a combustion chamber 10, the piston being in this case shown in top dead center. According to this embodiment, the air intake channel 12, which is connected inside the cylinder by transfer channels, for example the first channel 13, is shorter than the intake channel shown in FIGS. 1 and 2. An exhaust channel 15 is arranged, in the same horizontal plane, between the beginning and the end of the canal air intake. According to this form of execution, it is the fort eddy air movement which guarantees the evacuation of burnt gases. This embodiment includes a obturation device 16 which temporarily closes the channel exhaust in the first intake phase so as to prevent some of the admitted air from escaping through the channel exhaust.

Figures 8 and 9 show an embodiment of a cylinder 16 which comprises an intake channel 17, which comprises transfer channels, for example transfer channel 18, which is shorter than on the forms of executions shown on Figures 1, 2, 6 and 7. This embodiment comprises, on a part of the circumference of the cylinder, an exhaust channel 19 which is connected to the cylinder by transfer channels, the channel transfer 20 for example. Channel transfer channels exhaust are separated by vanes which form an angle by relative to the central axis of the cylinder. This form of execution with exhaust channel can allow better evacuation of burnt gases, depending on the vortex movement of the air admitted.

The number of different transfer channels can be varied according to the different engine designs, as well as the angles of the blades or of the upper or lower faces of the transfer channels.

The principle of the invention is independent of the number of engine cylinder, the principle can be applied as well single cylinder engines than multiple engines cylinders.

Claims (5)

1. A two-stroke diesel engine with a spiral-shaped air admission port comprising a cylinder (2) comprising transfer ports disposed at bottom dead center of a piston (9) comprising a combustion chamber (10), characterized in that a spiral-shaped air admission port (1) is disposed at the place of bottom dead center of the piston (9) on the greatest part of the circumference of the wall of the cylinder (2), the air admission port being connected to the cylinder by transfer ports separated from each other by vanes having an angle relative to the central axis of the cylinder such that air driven into the admission port and into the transfer ports is driven into the cylinder with a strong swirling movement around the central axis of the cylinder, and the upper and lower faces of the transfer ports progressively have an angle upward, the upper and lower faces of the transfer port disposed at the beginning of the admission port having a zero or very small angle relative to the horizontal plan and the upper and lower faces of the port disposed at the end of the admission port having a large angle upward relative to the horizontal plan such that air thus driven progressively toward the top of the cylinder creates an agitated movement.
2. The diesel engine of claim 1, characterized in that the spiral-shaped air admission port becomes progressively smaller from its beginning to the end.
3. The diesel engine of claim 1 or 2, characterized in that the air admission port has a spiral shape directed progressively downwards.
4. The diesel engine of claim 1, characterized in that an exhaust port is disposed in the same horizontal plane as the transfer ports admitting air, and said exhaust port is disposed on part of the circumference of the cylinder wall between the beginning and the end of the admission port.
5. The diesel engine of claim 1, characterized in that an exhaust port is disposed at the place of bottom dead center of the piston on part of the circumference of the cylinder wall, and said exhaust port is connected to the cylinder by transfer ports separated by vanes forming an angle relative to the central axis of the cylinder so as to facilitate escape of the exhaust gases in accordance with the swirling movement created in the cylinder.

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