DE2159490A1 - Exhaust system for an internal combustion engine and method for reducing the back pressure of the exhaust gases - Google Patents

Description

Clevepak Corporation (US 95 319 -prio December 4, 70

12-GER / 8106)

375 Park Avenue

New York, NY / USA Hamburg, November 29, 1971

Exhaust system for an internal combustion engine and method to reduce the back pressure of the exhaust gases

The invention relates to a device for increasing the working efficiency of internal combustion engines and in particular a system for reducing the back pressure in exhaust systems of internal combustion engines and a method to reduce the back pressure.

Since the development of internal combustion engines, the aim has been to increase their efficiency. A large number of procedures were used for this purpose, all of which had specific and had disadvantages. In this context, it suffices to point out that there is an important improvement method the efficiency of internal combustion engines reducing the back pressure on the outlet valves of the Engine is. It is known that in four-stroke Otto engines some of the energy generated during the explosion stroke is required to Combustion ™ during the fourth stroke to push products out of the cylinder through the exhaust valve and exhaust system. Can the resulting back pressure

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.reduced, the efficiency of the motor increases. A reduction in the back pressure in the exhaust line also enables an advantageous change in the structure of the Internal combustion engine cylinders. If the back pressure is lower, the cylinder outlet valves can be smaller be what allows for larger cylinder inlet valves. It is known that larger intake valves are advantageous because they have larger ones Allow amount of fuel-air mixture to enter the cylinder, which in turn increases the effectiveness of the cylinder. It A motor of a smaller size or a lower total weight can then be used to generate the same power.

From the above it follows that a device for reducing the back pressure in internal combustion engines was required in the past. In addition, the reduction of the back pressure in internal combustion engines is all the more important, the more you move on to arrange more and larger devices that slow down the exhaust gas flow between the outlet line of the engine and the surrounding air.

If exhaust gas detoxifiers are added to the exhaust systems of motor vehicles, a reduction in the back pressure is particularly important he wishes. All devices that put a negative pressure on the exhaust system of an internal combustion engine and thereby the Reduce back pressure, require a separate energy supply.

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It was the main disadvantage of the facilities that previously used to reduce the back pressure in internal combustion engines that they are a relatively high energy input needed to achieve a significant reduction in back pressure.

It is also already known that the introduction of air into the exhaust gases leads to a detoxification. This air can either simply to dilute the exhaust gases or in preparation for a subsequent decontamination step, for example Afterburning or catalytic conversion are added. However, there is no known way of this "Secondary air" to be supplied in the simplest possible way, in order to also reduce the back pressure in the exhaust pipe.

It is therefore the object of the invention to create a way of increasing the efficiency of internal combustion engines increase, in particular the efficiency of motor vehicle internal combustion engines.

This task is done with an exhaust system for an internal combustion engine with an exhaust pipe for the transport of exhaust gases from the engine into the surrounding air dissolved by a Device for reducing the back pressure of the exhaust gases in the exhaust pipe, which near the exhaust pipe a Filling chamber to which pressurized gas can be fed,

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and a nozzle opening between the exhaust pipe and the filling chamber for the exit of at least one jet of gas from the filling chamber into the exhaust pipe, the jet entering at an angle of 10 ° to 40 ° with respect to the main flow direction and at least "the speed of sound and a flow volume of about 20 % to about 40 % of the flow volume of the exhaust gases.

To generate the pressurized gas, a compressor can be used, for example, from the V-belt of the Internal combustion engine is driven.

The invention is explained in more detail below with reference to the figures explained.

Fig. 1 shows schematically the exhaust system of an internal combustion engine according to the invention.

Fig. 2 shows a section through the pump area of the exhaust system according to the invention.

Fig. 3 shows partially in section the end of the pump area of the exhaust system according to the invention.

1 shows a conventional internal combustion engine 1 to which a conventional exhaust gas manifold 2 is connected is that the exhaust gases from the cylinders of the engine

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records. A fan 3 seated on a fan shaft * 1 is driven in the usual way by the internal combustion engine. An endless belt 5 is wound around a pulley 6 which is in turn rigidly fixed to the fan shaft ¹ I. Furthermore, the endless belt 5 lies around the roller 7 on the input shaft of the compressor 8, which compresses air when the internal combustion engine is in operation.

The compressor should be at least about 1, ¹ Il kg / cm develop, and currently pressures are up to about 6.33 kg / cm considered the most appropriate for the production of compressed air. The prepared air for the compressor 8 may be recovered over a branch in the collecting line for the pump, as indicated in Fig. 1 through the branch ¹ Il and the line H2.

The outlet line of the compressor with the optionally provided control valve 9 is connected via a conventional tube connected to the input for the compressed air tank 12. The check valve 11 prevents pressure equalization over the line 10 and the compressor when it is not in operation.

The compressed air stored in the container 12 exits through a solenoid valve 13 and a tube I ¹ I and enters the filling chamber 15 of the torque pump 30. The coil of the magnet

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valve 13 can be electrically connected to the ignition circuit 16 of the internal combustion engine be connected so that the valve 13 opens when the ignition contact is closed and vice versa. the Air which has passed from the container 12 to the filling chamber 15 flows out of this chamber through nozzle openings 17 and 17 '(Fig. 3) and arrives in the main path of the torque pump 30.

It should be noted that the nozzle openings 17 and 17 ' have a very short extension in the direction of their longitudinal axes and that these central axes with respect to the central axis of the passage 18 of the torque pump form an angle in the range from 15 to 40. It should also be noted that the Ends of the nozzle openings 17 and 17 'which are at the rear in the direction of flow in the direction of the rear in the direction of flow show lying end of the passage 18 of the torque pump and that thus the air flow flowing at high speed with a force component running in the direction of flow on the relatively slow moving ones Exhaust gas flow in passage 18 meets.

At the rear end of the torque pump in the direction of flow, a diffusion device connected to the passage 18 can be arranged 20 may be provided. In this case, the rear end of the diffusion device 20 is connected to a line 21, which contains a device for treating the exhaust gas, such as an exhaust pipe or an exhaust gas decontamination device The gas emerging from this device is passed through an end pipe 23 into the surrounding air.

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The end 20a of the diffusion device which is at the front in the direction of flow has essentially the same internal shape and the same cross-section as the one at the rear in the direction of flow End of the passage 18, however, the diffusion device gradually increases its internal cross-section until the in The end 20b located at the rear of the flow direction is reached, the cross section of which has the cross section located at the front in the flow direction by up to about four times. Furthermore, the angle of the entering gas and the diameter of the gas inlet opening determine the distance between the opposite wall and the opening from which the gas emerges. It also makes the distance from the gas inlet opening to the beginning of the diffusion device is set. Experiments have shown that in one rectangular chamber with internal dimensions of 1.21 cm χ 3.8l cm and with two gas inlet openings with an angle of 22 and a diameter of 2.08 mm a distance of about 6.35 cm from the gas entry point to the start of the diffusion device is required for a pump of this size to achieve maximum efficiency.

The operation of the exhaust system described above is shown below. When the ignition contact of the ignition circuit l6 closes, the solenoid valve 13 opens, and compressed air flows from the compressed air ^{tank 12 through the pipe I 1} I and into the filling chamber 15 of the torque pump. At the same time, the internal combustion engine is started and the fan shaft H begins to rotate. As a result, the compressor 8 is driven via the roller 6, the endless belt 5 and the input shaft 7, the compressor 8 via the outlet line, the valve 9, the pipe 10 and

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the check valve 11 conveys compressed air into the container 12.

During operation of the internal combustion engine 1, exhaust gases are generated which are combined in the outlet manifold 2 and become move through the exhaust pipe to passage Γ8 of the torque pump. Looking at Pig. 3 »so you can see that from the container 12 supplied compressed air reaches the filling chamber 15 and stabilized there before flowing out through the jet openings will.

This compressed gas then flows at sonic or supersonic speed through the short, substantially circular nozzle openings 17 and 17 'and occurs at this speed into the passage 18.

The circular openings extend through the wall of the Passage 18, so that the actual outlet openings in the passage have a substantially elliptical shape. It it is believed that this form is essential to effectiveness. contributes to the torque pump.

When exiting the nozzle orifices, the air flow, which flows at high speed in the direction described, is generated a very turbulent eddy current. Because of the shear forces between the laminar exhaust gas flow and the ventilation vortices there is a mixture of air and exhaust gas. It is believed, however, that because of the very effective torque transfer from the

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rapid air flow on the relatively slowly moving exhaust gas flow in passage 18 is a rather mechanical one The helical effect of the air vortex takes place, through which the exhaust gas flow forwards in the direction of the flow direction the rays are moved. Investigations have shown that the rapid air flows from the nozzle openings each one Generate pair of oppositely directed eddy currents, which are denoted by 2 * J in FIG. 3. These very fast eddy currents The exhaust gases "rotate" by shear action, roughly in the manner of the rotation of a rigid body (FIG. 3). If the Exhaust gases only "turn", so they retain this torque without any significant additional shear effect and corresponding Changes in viscosity arise. The torque pump thus results in a considerable improvement in operation. It is used to transfer a moment from a relative small flow volume of a fast flowing gas to a large flow volume of a relatively slow flowing gas, which significantly increases the speed of the latter, thereby increasing a substantial Improvement compared to conventional venturi devices results.

Because the nozzle openings, as described, at an angle are arranged, the introduced into the passage 18 has a force component in the flow direction and in the axial Direction runs. This causes the turbulent mixture of compressed air and exhaust gas to be at the rear in the direction of flow

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Driven at the end of the torque pump. "Looking at the course three-dimensional, so the nozzle openings create helical vortices, which the mixing and the torque transfer between the compressed air and the exhaust gas significantly improve. Although the vortex courses have a lower force component in the desired Flow direction than the laminar flow can have, the effect of the intensive mixing is very beneficial.

At the rear end 20a of the passage 18 in the flow direction, a diffusion device is arranged, which the Effect of the torque pump even further improved. Diffusion devices are usually used in flow systems Subsonic speed used to reduce the speed and static pressure of the passing through Increase pluides. The use of a diffusion device at the rear in the direction of flow thus initially appears lying end of a pump unsuitable for the purposes of the invention, since the pump is a pressure reduction by a to cause very rapid gas flow. Nevertheless, the addition of a diffusion device to that described results The torque pump further increases the "effectiveness" of the pump by at least about 25 ί. This unexpected result, that is, the increase in effectiveness, should result from the conversion of energy by rotating in a tangential direction Air vortices result in a rotating movement in the axial direction. The supplied air jets exercise on the laminar Flow of the exhaust gases from a strong, tangential "rotation",

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so that corresponding kinetic energy is stored. By gradually widening or enlarging the Cross-section of the diffusion device is the stored kinetic energy, which both in tangential and in acting in the axial direction, converted into pressure energy, which acts in the direction of flow, so that the effectiveness of the pump is increased.

It can be seen that by increasing the speed of the exhaust gases in the exhaust line, the "back pressure" normally prevailing in front of the outlet opening or the outlet manifold of the engine is considerably reduced. Although the flow volume of the supplied air is generally only a small fraction of the flow volume of the exhaust gases to be treated, for example only about 10 % to 50% and preferably no more than 20 %, these beneficial effects are achieved. If a diffusion device is used, its outlet is connected via a line 21 to an exhaust gas decontamination device 22, from which an outlet pipe 23 leads into the surrounding air.

The invention has been described above in connection with a preferred operation in a motor vehicle exhaust system. It is clear, however, that many modifications and changes can be made by those skilled in the art. So instead of one. Compressor a turbine can be used, as it is used in pre-compressors, so that this is then compressed air into the

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Filling chamber 15 of the torque pump conducts.

While the compressor is driven by the fan shaft in the illustrated embodiment, any other drive is also possible, for example via an electric motor that is fed by the alternator driven by the internal combustion engine. Furthermore, other drive devices not belonging to the internal combustion engine can be used. In addition, the compressed air tank 12 with the associated valves and the connections can be omitted, and the output of the compressor device can be connected directly to the filling chamber 15 of the torque pump. In this case, of course, when starting, a smaller flow of compressed air is obtained for the filling chamber 15 , so that the torque pump does not work fully effectively. In some cases, however, this modification has the advantage of an automatic adjustment of the flow rate of the pressure and flow rate of the exhaust gases passing through the passage 18 which are conducted into the filling chamber 15.

Although in the present case the torque pump is arranged between the outlet manifold and the detoxification device it can also be behind the detoxification facility or the exhaust. It is also possible to attach them close to the outlet manifold. In addition, several such torque pumps can be arranged in the output lines of the individual cylinders,

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which lead into the collecting line, or there can be such a pump in front of the exhaust gas detoxifier and a second pump behind this should be provided. In either case, the operation is essentially the same as described above.

In addition to or instead of an exhaust gas decontamination system a conventional exhaust can also be provided.

While in the embodiment a torque pump with _Λ

two short nozzle openings is shown, a pump with only one or with more than two openings can also be used. In these cases, the shape of the passage 18 to achieve the greatest possible effectiveness by appropriate Tests and pressure measurements are determined. The use of at least two such nozzle openings for a passage 18 of substantially rectangular cross-section provides better pumping action than a single orifice. Studies have also shown that with a desired increase in the passage size in the torque pump without a reduction ™ the pumping action, the relative height of the passage should be essentially maintained, while the width should be gradual can be enlarged if an additional opening is provided which is the same at a half enlargement of the width Size and the same angular position as the two nozzle openings shown and is on the center line of such Dissemination step.

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Also not essentially rectangular passages 18 fall under the invention. For example, the passage can be circular (especially for pumps with a single nozzle opening), or hexagonal or any other regular or irregular cross-sectional shape. The most important criterion for the best results in a facility is the proper spacing of the nozzle openings from each other, so that there is a maximum vortex effect, which in most cases means that there is minimal vortex disturbance and adjust energy losses. In some cases, for example with three nozzle openings, one of the openings be arranged at a point downstream or upstream with respect to the other two nozzle openings. If the number of the nozzle openings is increased, of course the size of the filling chamber changes, the internal shape of which is not critical, so that a corresponding source of stabilized air is obtained for all openings. It is in the working examples It is important that the nozzle opening has a minimum length.

While the fluid generating the moment was air above, it is also possible to use a gas other than air for the exhaust gases to add. For example, ammonia can be added for exhaust gas detoxification.

If a gas other than air is to be added, the compressor 8 and the container 12 can be through a container replaced with the desired compressed gas.

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From the above description it follows that the capacity of the compressed air source should be sufficient to the To keep the filling chamber in the desired pressure state. In addition, the filling chamber should be large enough to accommodate during the Not to be completely emptied. Furthermore, sufficiently small nozzle openings are required to to achieve an exit of the compressed gas at supersonic speed, while at the same time the exiting volume must be sufficient to accelerate the flow in the passage to the desired speed, that is, the Jet stream must have both a mass and a velocity sufficient to produce the desired torque produce.

It is clear that the dimensions of the various elements (e.g. pressurized gas source, filling chamber, nozzle openings, passage 5 " be selected according to the desired reduction in back pressure.

In general, the nozzle orifices have a length that is between 1/2 and twice their diameter, whereby effective operation results. The practical limitation of the length of the nozzle openings results from the requirement after a sufficient wall thickness for the formation of the openings and the passage.

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In addition, the exit areas of the nozzle openings should essentially be aligned with the surrounding wall of the passage align, since it is assumed that just such a structure significantly improves energy transfer contributes from the fast gas flow to the relatively slow exhaust gas flow.

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Claims (1)

Expectations . \ Exhaust system for an internal combustion engine with an exhaust pipe for transporting exhaust gases from the engine into the
surrounding air, characterized by a device for reducing the back pressure of the exhaust gases in the exhaust pipe, which near the exhaust pipe has a filling chamber (15), the
pressurized gas can be supplied, and at least
a nozzle opening (17, 17 ') between the exhaust pipe and
Filling chamber for the exit of at least one jet of gas from the filling chamber (15) into the exhaust pipe (18), the jet entering at an angle of 10 ° to 40 ° with respect to the main flow direction and at least the speed of sound and a flow volume of about 20 % up to about 50 % of the flow volume of the exhaust gases. 2. Exhaust system according to claim 1, characterized by a compressor driven by the internal combustion engine for generation of pressurized gas. 3 · Exhaust system according to claim 1 or 2, characterized by a pressurized gas container (12). k. Exhaust system according to one of Claims 1 to 3, characterized
characterized in that the nozzle opening (17, 17 ') consists of a circular bore which is at the transition to 209830/0540 ^A ° Exhaust pipe forms an elliptical opening. 5. Exhaust system according to one of claims 1 to 4, characterized characterized in that between the supply source for the pressurized gas and the sub-chamber (15) a Pressure control device (13) is provided. 6. Exhaust system according to one of claims 1 to 5, characterized characterized in that in the direction of flow behind the connection of the exhaust pipe and nozzle opening one Flow smoothing device (20) is provided. 7. Exhaust system according to claim 6, characterized in that the flow smoothing device consists of one Diffuser (20) is made, the cross-section of which is located at the rear in the direction of flow is larger than its in Direction of flow in the front cross-section and the length of which is greater than its length in the direction of flow behind lying transverse extension. 8. Exhaust system according to one of claims 1 to J, characterized in that the exhaust line has a rectangular cross-section in the region of the filling chamber. 9. Exhaust system according to claim 8, characterized by a A plurality of nozzle openings, all of which extend through a longitudinal side of the rectangular exhaust pipe 209830/0540 and which are spaced apart so that the mutually directed eddy currents generated are mutually exclusive not affect. 10. Exhaust system according to one of claims 1 to 7, characterized in that the exhaust pipe in the area of Filling chamber has a circular cross-section and that a single nozzle opening in a vertical central plane is arranged. 11. Exhaust system according to one of claims 1 to 10, characterized characterized in that a single exhaust pipe between the exhaust manifold of the internal combustion engine and the Exhaust gas treatment device is provided. 12. Exhaust system according to one of claims 1 to 10, characterized in that between the exhaust gas processing device and there is a single conduit for the surrounding air. 13. Exhaust system according to one of claims 1 to 10, characterized by a plurality of lines, of which at least one is provided on each side of the exhaust gas treatment device. lH. Method of reducing the back pressure on the Exhaust valves of an internal combustion engine, characterized in that in the outgoing from the exhaust valves 209830/0540 Exhaust pipe a certain amount of a pressurized gas is introduced into the exhaust pipe, the under Pressurized gas is introduced at an angle with respect to the axis of the exhaust pipe and at such a speed is that a moment acting in the outflow direction is transmitted to the exhaust gases in the exhaust pipe. 15. The method according to claim 14, characterized in that about 10 % to 50 % of the volume of the exhaust gases making up volume of pressurized gas is introduced into the exhaust pipe. 16. The method according to claim I ¹ J or 15 j, characterized in that the gas introduced into the exhaust pipe has sonic or supersonic speed. 17. The method according to any one of claims Ik to l6, characterized in that the gas is introduced at an angle of 10 to ^ 0 ° with respect to the axis of the exhaust pipe. 18. The method according to any one of claims I ^ to 17, characterized characterized in that the gas is supplied from the manifold of the internal combustion engine and compressed to a pressure and is brought to a temperature higher than that in the manifold. 209830/0540 2159A90 19. Method according to claim 18, characterized in that ambient air is added to the gas. su: sch. 209830/0540 Blank page