GB2535526A

GB2535526A - Exhaust system

Info

Publication number: GB2535526A
Application number: GB1502953.1A
Authority: GB
Inventors: Hasan Muwaiza Abdulrahman
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-02-23
Filing date: 2015-02-23
Publication date: 2016-08-24
Also published as: GB201502953D0

Abstract

An exhaust system 10, for a combustion engine E, comprises an exhaust pipe 20, a fan 30, a venturi duct 40 and a bypass pipe 50. The exhaust pipe and the bypass pipe are connected with the venturi duct. In operation, the fan ventilates the venturi duct which generates a pressure drop within the exhaust pipe and drives the exhaust fumes towards a tail pipe 70. The fan may be located upstream of the venturi duct, in the bypass pipe, or downstream of the venturi duct, in the tail pipe. Ambient air may be fed to the bypass duct. The fan may be electric. The bypass duct may be connected to the compressor of a turbocharger. A fan bypass 50 may be provided. Also disclosed is an exhaust system comprising a fan located in an exhaust pipe, downstream from a combustion engine.

Description

Title: Exhaust System

BACKGROUND

Field of the invention

[0001] The present invention relates to an exhaust system for an internal combustion engine. The invention specifically relates to an exhaust system that reduces the exhaust back pressure in the exhaust system.

Background of the Invention

[0002] A reduction in the exhaust back pressure in the exhaust system will result in an increase in performance of an internal combustion engine with regard to output power of the internal combustion engine as well as an improvement in the characteristics of the speed of rotation of the internal combustion engine and/or the turbocharger. Fuel consumption of the internal combustion engine can also be reduced by decreasing the exhaust hack pressure in the exhaust system.

[0003] Reduction of the exhaust back pressure reduces efficiency loss due to drag in the internal combustion engine. The drag generates a load when one piston in one cylinder of the internal combustion engine uses in, an expansion phase of the combustion cycle, some of its power to force out exhaust gases in another one of the cylinders, which is in the exhaust phase of the combustion cycle and is connected via a same crankshaft. The drag and/or load increases significantly with an increase in the internal combustion engine's speed of rotation.

[0004] Numerous improvements in the art are known that relate to the intake system (for example turbochargers, compressors, etc.). The exhaust system in the art was improved merely by improving the dynamic behavior of the gases within the exhaust system, such as the use of a fan-type exhaust pipe, etc. However, these improvement measures in the exhaust system were achieved by use of passive components.

Summary of the Invention

[0005] The present disclosure teaches an internal combustion engine with reduction in the back pressure in an exhaust system.

[0006] According to one aspect of the present disclosure, an exhaust system comprises an exhaust pipe, a fan, a venturi duct and a bypass pipe. The bypass pipe and the exhaust pipe are connected with the venturi duct.

[0007] According to another aspect of the present disclosure, the fan is located upstream of the vcnturi duct in the bypass pipe. The fan is, in this aspect, not in contact with hot exhaust gases and has, as a result, a longer life as it is not subject to large thermal stresses and/or chemical attack from the exhaust gases. The fan can be cheaper to manufacture as less expensive materials can he used. In countries, such as the UAE, with high humidity and temperatures and also a saline environment, specialized materials are used and these are less susceptible to environmental attack at lower temperatures.

[0008] According to another aspect of the present disclosure, the fan is located downstream of the venturi duct. This enables location of the fan in the exhaust system between the venturi duct and the tail pipe.

[0009] According to another aspect of the present disclosure, ambient air is fed into the bypass pipe. The expression "ambient air" in the scope of this disclosure means "untreated" outside air, filtered air or air that has been compressed by a compressor or by a turbocharger (intercooled or not). The ambient air can reduce the temperature of the exhaust gases. The reduction of the temperature will also result in a lower noise as it is know that the expulsion of hot gases from the bypass pipe results in additional noise.

[0010] The ambient air can be external air that is directly led to the venturi duct and thus the generated pressure drop in the venturi duct is, at least partially, dependent on the air speed of the external air led to the venturi duct. The fan can further he driven by such an incident air flow being directed towards the fan and then to the venturi duct.

[0011] It is also possible to use the fan in such cases when the air flow outside the exhaust system is not present or the air flow is insufficient to ventilate sufficiently the venturi duct. An increase in the velocity of the vehicle increases the incident air flow and the air flow from the fan can be, at least partially, replaced by this incident air flow by means of a fan bypass. The incident air flow can be, for example, wind or any other usable air current for stationary internal combustion engines.

[0012] Flow rate of the air flow through the bypass pipe can be controlled by at least one valve. The use of the valve is optional since the bypass pipe can be designed such that, for a certain maximum flow rate created by the fan, the bypass pipe provides for less flow resistance and thus the gas flow (upstream or downstream of the venturi duct) will mostly pass through the bypass pipe than through the fan.

[0013] The exhaust system of the present disclosure can at least partially use the ram pressure effect to reduce the back pressure in the exhaust system by ventilating the venturi duct.

[0014] In the case of the stationary internal combustion engine, the incident air current can be used to ventilate, at least partially, the venturi duct. In the case of the internal combustion engine used in a vehicle, the venturi duct can he, at least partially, ventilated by the air flow generated through a head wind that occurs when the vehicle is moved. The vehicle can be any kind of vehicle, such as a seaborne vehicle, a land vehicle or an airborne vehicle.

[0015] According to another aspect of the present disclosure, the bypass pipe is connected to a compressor section of a turbo charger. The flow rate in the venturi duct is increased and thus the pressure drop generated by the venturi duct is also increased.

[0016] The exhaust system according to another aspect of the disclosure comprises the 30 exhaust pipe and the fan being located downstream of the internal combustion engine. This enables a simplification in the structure of the exhaust system. However, the fan has to bear an increased thermal stress due to the temperature of the exhaust gases.

[0017] According to another aspect of the present disclosure, the fan is an electric fan. Electric fans are well known in the art, for example from their use in multi-stage charging configurations using several turbo chargers. However, the exhaust system can use any kind of fan (hydraulically driven, gas driven, etc.). However, the present invention can also be implemented by using a gas flow generated from a turbo charger or from a compressor that is already present in the internal combustion engine.

[0018] A method for reducing the back pressure in an exhaust system comprises the steps of: generating exhaust gases in an internal combustion engine, switching on a fan located in an exhaust pipe to drive the exhaust gases out of the exhaust system towards a tail pipe.

[0019] A method for reducing the hack pressure in an exhaust system according to the present invention comprises the steps of: generating exhaust gases in the internal combustion engine, switching on the fan located in the bypass pipe to drive the exhaust gases out of the exhaust system towards a tail pipe, ventilating a venturi duct by means of the fan, generating a pressure drop within a exhaust pipe induced by the ventilated venturi duct. This enables the efficiency of the combustion engine to be increased.

[0020] According to another aspect of the disclosure, the method comprises the further step of introducing ambient air to the exhaust system. The hot exhaust gases are cooled by the introduced ambient air.

[0021] All above features can he present in the various embodiments of the invention.

The above features can freely be combined with each other.

[0022] The invention will be explained with regard to the internal combustion engine having more than one cylinder. However, the effect with a single cylinder engine is essentially the same since, in this case, kinetic energy of the rotating parts of the engine -for example a flywheel -is used to force out the exhaust gases and thus the loss of efficiency due to the drag / load reduces the kinetic energy. This reduction in the kinetic energy, for example, slows down the flywheel. The invention further improves the efficiency of the burn of the fuel in the cylinder. Since the exhaust gases are drawn out of the cylinder at the end of an exhaust stroke, less residue of burnt gas remain in the cylinder when unburnt gases flow into the cylinder at a new intake stroke.

Description of the Drawings

[0023] Referring now to the attached drawings which form part of this original disclosure: [0024] Figure 1 is a schematic view of an exhaust system according to one aspect of the present invention comprising a venturi duct and a fan upstream of the venturi duct.

[0025] Figure 2 is schematic view of an exhaust system according to another aspect of the present invention comprising a venturi duct and a fan downstream of the venturi duct.

[0026] Figure 3 is a schematic view of an exhaust system according to another aspect of the present invention comprising a fan in the exhaust pipe.

[0027] Figure 4 shows an overview of a method.

[0028] Figure 5 shows an overview of another method [0029] An exhaust system according to the present invention may comprise further elements (e.g. mufflers, etc.) known in the art downstream of the depicted sections in the above features. It is accordingly only indicated that the exhaust gases are transported towards a tail pipe.

Detailed Description of the Invention

[0030] Selected embodiments will now he explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0031] Initially referring to Fig. 1, an exhaust system 10 is disclosed. The exhaust system 10 comprises an exhaust pipe 20, a fan 30, a venturi duct 40, a bypass pipe 50 and a fan bypass 60. The exhaust pipe 20 is connected to one or more exhaust valves of the individual cylinders of an internal combustion engine E. Preferably a manifold unites the exhaust gas flows of each of the individual cylinders before the exhaust pipe 20 leads the exhaust gas flows to the venturi duct 40.

[0032] The exhaust pipe 20 is connected to the venturi duct 40 in the region of a reduced cross section of the venturi duct 40 (venturi constriction). When the venturi duct 40 is ventilated, a pressure drop within the exhaust pipe 20 is generated and accordingly the exhaust gases are dragged out of the exhaust pipe 20 and thus out of the cylinders of the internal combustion engine E. [0033] This pressure drop reduces the drag and/or load of the internal combustion engine E since the cylinder in the expansion phase of the combustion cycle can more easily force out the exhaust gases of another cylinder in the exhaust phase of the combustion cycle and connected to the same crankshaft. This results in an improved spool up rate of the crank shaft, which means the internal combustion engine E and/or the crank shaft reacts more quickly to changes on an accelerator. The spool down rate may be slower unless it is adjusted by other means, such as reducing the amount of fuel supplied to the internal combustion engine.

[0034] In the aspect depicted in Fig. 1 the fan 30 is located in the bypass pipe 50 and ventilates the venturi duct 40. The fan 30 thus causes a pressure drop in the exhaust pipe 20. The fan 30 can be any type of fan as long as it is suitable to produce a required flow rate for a proper function of the venturi duct 40.

[0035] In one aspect of the disclosure, electric fans are used since the electric fans are easy to arrange and, due to the recent development of electric turbo chargers, the electric fans are available that have a high speed of rotation and accordingly a high generated flow rate and pressure.

[0036] In the aspect depicted in Figure 1, the bypass pipe 50 is fed with ambient air. The fan 30 increases the air flow of the ambient air fed to the venturi duct 40. Within the venturi duct 40 the exhaust gases dragged out of the exhaust pipe 20 are mixed with the ambient air from the fan 30. This mix reduces the temperature of the exhaust gases leaving the venturi duct 40 and is beneficial for the placement (design) of the exhaust system downstream of the venturi duct 40 towards a tail pipe 70.

[0037] A vehicle in use creates a certain amount of head wind essentially dependent on its velocity. This head wind or ram pressure can be used to ventilate the venturi duct 40 (ram-air effect). This ram-air effect can be exploited to provide an incident air current and, in this case, the exhaust system 10 can be provided with a fan bypass 60. This fan bypass 60 can he used to at least partially ventilate the venturi duct 40 by bypassing the fan 30. The fan bypass 60 optionally can be controlled by at least one valve (not shown) that controls a flow rate within the fan bypass 60.

[0038] Referring now to Figure 2, another aspect of the present disclosure is depicted. The exhaust system 110 according to Figure 2 is provided with an exhaust pipe 20, a fan 130, a venturi duct 40, a bypass pipe 50 and a fan bypass 60. The exhaust pipe 20 is connected to the exhaust valves of the individual cylinders of the internal combustion engine E. A manifold can he used to unite the exhaust gas flows of each individual cylinder before the exhaust pipe 20 leads the exhaust gases to the venturi duct 40.

[0039] As noted above, the exhaust pipe 20 is connected to the venturi duct 40 in the region of the reduced cross section of the venturi duct 40 (venturi constriction). When the venturi duct 40 is ventilated, a pressure drop within the exhaust pipe 20 is generated and accordingly the exhaust gases are dragged out of the exhaust pipe 20 and thus out of the cylinders of the engine E. [0040] The fan 130 can be located downstream of the venturi duct 40 in the exhaust system 110 depicted in Figure 2. The fan 130 thus drags air into the bypass pipe 50 and accordingly changes the air flow within the venturi duct 40, creating the pressure drop at the venturi constriction in the venturi duct 40 in which region the exhaust pipe 20 is connected to the venturi duct 40. The effect is the same as described above. The exhaust gases are dragged out of the exhaust pipe 20 and thus the exhaust back pressure is reduced.

[0041] The air in the bypass pipe 50 and the exhaust gases are initially mixed in the venture duct 40. The fan 130 in Figure 2 will further mix the cooled exhaust gases and push the cooled exhaust gases through the downstream exhaust system 110. This push means that any resistance to the flow, such as pipe bends, catalytic converters, mufflers etc., to he compensated, at least partially.

[0042] If an air current generated external to the exhaust system is used, the fan bypass can be provided in the exhaust system 110. The fan bypass 60 can bypass the fan 130 if the incident air current from outside the exhaust system is used to ventilate the venturi duct 40. The fan bypass 60 optionally can he controlled by at least one valve that controls a flow rate within the fan bypass 60.

[0043] The fan 130 in the exhaust system 110 needs to tolerate the increased thermal stress resulting from the exhaust gases being mixed with the incident air in the venturi duct 40, as well as the environmental influences noted in the introduction. The system of Figure 2 enables the incident air current or ram-air effect to be used to ventilate the venturi duct 40 and the fan 130 further can compensate any flow resistance in the exhaust system downstream of the fan 130.

[0044] The aspect depicted in Figure 3 is an exhaust system 210 comprising the exhaust pipe 20 and the fan 230. The fan 230 drags the exhaust gases out of the exhaust pipe 20 and thus out of the cylinders and conveys them towards the tail pipe 70.

[0045] In case of figure 3, the fan 230 has to tolerate the thermal stresses of the exhaust gases, as known from a conventional turbo charger for example. The exhaust system 210 is its simple to design and manufacture. The exhaust system 210 can he arranged directly downstream of each individual cylinder of the internal combustion engine E and thus can compensate for example different path lengths in the exhaust system 210. A manifold can be used to unite the exhaust gas flows of each individual cylinder before the exhaust pipe 20 leads the exhaust gases to the venturi duct 40. A bypass may be provided around fan 230 as well, which is not depicted in Figure 3.

[0046] In cases of the exhaust system 10 and 110 depicted in Figures 1 and 2, any compressed gas can he used to ventilate the venturi duct 40. For example, a compressed and stored gas such as compressed air can he used to ventilate the venturi duct 40.

[0047] The exhaust system 110 provides a controllable air flow at an air flow rate within the exhaust system 110. This is useful if a turbo charger is placed in the exhaust system. The so called "turbo lag" can at least he compensated since the flow rate through the turbo charger and thus the speed of rotation of the turbo charger can he controlled by controlling the air flow rate through the turbo charger by means of the incident air current outside the exhaust system and / or the flow rate generated by the fan.

[0048] In the case of the exhaust system 10, 110, as illustrated in Figures 1 and 2, the turbo charger can be produced more cheaply, since the thermal stresses due to the temperature of the exhaust gases are reduced.

[0049] Referring now to Figure 4, a method for using the system according to the exhaust system 210 depicted in Figure 3 will be described. In step S11, the exhaust gases are generated in the internal combustion engine E. The fan 230 is then powered in step S12 to drive out the exhaust gases in step S13 towards a tail pipe 70.

[0050] Referring now to Figure 5, another method for using the exhaust system 10, 110 of Figures 1 and 2 will be described. In step S21, the exhaust gases are generated in the internal combustion engine E. Then the fan 30, 130 is powered in step S22 to drive out the exhaust gases towards the tail pipe 70 in step 523. The powered fan 30, 130 further ventilates the venturi duct 40 in step S24 and consequently generates a pressure drop in step S25 within the exhaust pipe 20.

[0051] The methods with regard to Figures 4 and 5 are described as a successive series of steps; however, it will he appreciated that the steps can he performed simultaneously.

Claims

-10-Claims An exhaust system (10) for a combustion engine (E) comprising: an exhaust pipe (20); a fan (30, 130); a venturi duct (40): and a bypass pipe (60), wherein the exhaust pipe (20) and the bypass pipe (50) are connected with the venturi duct (40).
The exhaust system according to claim I, wherein the fan (30) is located upstream of the venturi duct (40) in the bypass pipe (60).
3. The exhaust system according to claim 1, wherein the fan (130) is located downstream of the venturi duct (40).
4. The exhaust system according to claim 2 or 3, wherein ambient air is fed into the bypass pipe (60).
5. The exhaust system according to claim 1, wherein a bypass pipe (60) is connected to a compressor section of a turbo charger (T).
6. An exhaust system (210) connectable lo a combustion engine (E) comprising: an exhaust pipe (20); and a fan (230) located in the exhaust pipe (20) downstream of the combustion engine (E).
7. The exhaust system according to one of the previous claims, wherein the fan (30, 130, 230) is an electric fan.
The exhaust system according to one of the previous claims, further comprising a bypass pipe (60).
9. An internal combustion engine (E), comprising an exhaust system (10, 110, 210) according to one of claims 1 to 8.
10. A method for reducing exhaust hack pressure in an exhaust system (110, 210) comprising: generating (S11) exhaust gases in a combustion engine (EE); powering (S12) a fan (130, 230) located in an exhaust pipe (20) to drive the exhaust fumes out of the exhaust system (10) towards a tail pipe (70).
11. A method for reducing exhaust back pressure in an exhaust system (10) comprising: generating (S21) exhaust fumes in an combustion engine (60); powering (S22) a fan (30) located in a bypass pipe (50) to drive (523) the exhaust fumes out of the exhaust system (10) towards a tail pipe (70); ventilating (S24) a venturi duct (40) by means of the fan (30); generating a pressure drop within the exhaust pipe (20) induced by the ventilated venturi duct (40).
12. The method of claims 10 or I I, further comprising introduction of ambient air into the exhaust system (10).
13. The method of claims 10 to 12, further comprising the step of at least partially bypassing the fan (30).