Patent Details
DESCRIPTION
VACUUM CREATING EXHAUST MUFFLER
FOR INTERNAL COMBUSTION ENGINES
Technical Area
This invention relates to a muffler which is designed to create vacuum by reducing the back pressure at the exhaust of internal combustion engines below the atmospheric pressure, and keep it at a certain constant value independently of the engine operating conditions, and which is effective basically in sound absorption and mechanical frequency interference and, in addition, can also make use of the electronic frequency interference effect, both due to its structure.
Known Status of Technical Area
When the pistons of an internal combustion engine are in the exhaust cycle, exhaust gases arising as a result of ignition in the pistons are discharged from the engine body into the atmosphere owing to the existing exhaust system. Therefore, the back pressure faced by pistons in discharging gases is the sum of the atmospheric pressure and the pressure losses in the exhaust system. For the exhaust systems that are known today, the lowest back pressure is around the atmospheric pressure in Formula 1 racecars. In such an exhaust system, exhaust gases directly open into the atmosphere, with no muffler nor any another element present on the exhaust pipe.
Since a reduced back pressure provides an additional power and fuel saving to the engine, this is preferable by vehicle manufacturers. However, because of the severe limits imposed by environmental health protecting authorities upon the noise levels created by vehicles, it is not possible to reduce the back pressure to the atmospheric pressure except for racecars used in special raceways. This requires that the exhaust muffler system consisting of intermediate and final mufflers in the exhaust line have to be built so as to yield sound intensity levels acceptable to environmental authorities. A muffler system operating more efficiently in general and reducing the noise level significantly will increase the back pressure. Therefore, vehicle manufacturers have to find an optimum solution between the back pressure and the sound intensity and apply it in their vehicles.
Today, various forms of the mufflers described below are mostly used for vehicles.
1. This is a traditional muffler, which is most commonly used. The frequency interference chamber allows the interference of sounds of varying frequencies to reduce the sound intensity. The flow from the inlet pipe to the outlet pipe is enabled through perforations. It is a system where the back pressure is high while the sound intensity is reduced most optimally. Whenever it is desirable to reduce the back pressure, this muffler is replaced with one of the following.
2. This muffler replaces a traditional muffler and is commonly used for sportive purposes. After the exhaust pipe enters in this muffler, it becomes perforated. The muffler function is performed by glass wool or rock wool wrapped around it. A somewhat smaller body appearing to be a traditional muffler includes all.
3. This muffler is used for sportive purposes. High-frequency exhaust gases pass all through the muffler. Low-frequency exhaust gases exiting outwards from the perforated exhaust pipe interfere with high-frequency sound waves exiting from the end of the muffler, causing a reduction in the sound intensity.
4. This is another type of mufflers, which is used for sportive purposes. It comprises a perforated exhaust pipe and a Plexiglas body enclosing it. When exhaust gases passing through the exhaust pipe enters through the conical surface of the Plexiglas body, they pass through perforations owing to the air with an increased velocity and a reduced pressure and cause a frequency interference with high-velocity air, thus causing a reduction in the sound intensity.
5. This is a part fitted on the end of the exhaust pipe that comes out of the existing muffler. As the air entering in around this part passes through fixed vanes, a rotating stream of air develops, giving rise to a swirl that suctions out gases from the end of the exhaust pipe in the center.
6. This muffler reduces the sound intensity highly effectively and is suitable for any and all uses. The exhaust pipe in the muffler is not perforated, it is rather plain. Therefore, pressure losses are smaller with this muffler than with previous ones. When the air entering peripheral channels at inlet of the muffler goes back again and interferes with exhaust gases in the inlet, an effective reduction of sound intensity is ensured.
This muffler, subject of the invention, creates vacuum owing to a venturi (5) located at the center of its body, which extends all therethrough. This venturi is a shape developed by connecting two conical nozzles (5.1 and 5.3) by their ends entering into a narrow and perforated cylinder (5.2) at the center, whereby, based on Bernoulli Equation for gases, the speed of the air sucked into the nozzle from the wider end can give rise upto the speed of sound inside the throat, which is the narrowest section of the venturi. Depending on this speed, the air pressure in this section drops down drastically below the atmospheric pressure to create vacuum, and the gases outgoing from the engine thus are sucked into this vacuum medium. By the structure of its body, the muffler is able to reduce the sound intensity of gases expanding into the body at the extreme level by their passing first through the mechanical muffler ensuring sound absorption and frequency interference and then, if desirable for a quieter environment, through an active noise control system ensuring a second-stage electronic sound frequency interference.
The Subject Invented Muffler and its Application
This subject invented muffler drops the back pressure at the exhaust outlet below the atmospheric pressure owing to the vacuum created at the throat (5.2) of its venturi-shaped body, using a flow of air generated by means of a double stage, high and constant speed air pump (vaneaxial fan) (2) driven by a high-voltage direct-current motor (1.1 or 1.7) supplied from the battery in the vehicle or a double stage, high and constant speed air pump (axial fan) (9.1, 9.2, 9.3, 9.4, 9.5, 9.6) driven by a reaction turbine (8.7, 9.7, 9.8), operated by compressed air (8.5, 8,6) thereby speeding up the suction of exhaust gases into the venturi throat (5.2) and thereoutwards, and thus dropping the pressure, temperature and quantity of residual gases remaining in the pistons. This, in turn, causes an increased volumetric efficiency of the engine and ensures that more work can be done for the same piston volume, thereby increasing the engine power and providing fuel saving.
This subject invented muffler is a compact muffler that also carries out the functions of intermediate and final mufflers in a normal vehicle. At the same time, due to the convenience of its shape, this muffler can also readily house in it an electronic active noise control system, which is the subject of another patent already granted to elseone. The use of this system in this muffler, the greatest disadvantage of which is known as the blockage of the exhaust gases upstream, is possible with a minimum loss of pressure.
That the sub-atmospheric back pressure (vacuum) caused by this subject invented muffler due to its venturi-shaped body remains constant at the highest value under all operating conditions (speed end engine cycle) of the vehicle ensures the use thereof optimally and efficiently.
With this subject invented muffler, a vacuum up to approximately 0,6 Bar(a) can theoretically be produced at exhaust outlets at all engine speeds under the atmospheric pressure from the moment the engine is started. The muffler's efficiency to produce vacuum depends on the adequacy of the air entering the muffler and sucked by the axial fan at the other end of it. Therefore, the air entering the muffler must be guided correctly for an efficient use of the muffler. On the other hand, the subject invented muffler should be put as near the manifold outlet of the motor as possible in order to reduce losses of pressure. Proper uses of the muffler on the vehicle are exhibited in Figures 1 and 2 in the next section. In both uses, it would be better to install the muffler in the vehicle on the assembly line. Underbody constructions used in respective vehicle production will be so as to contain this muffler and ensure air intake into it easily.
This muffler can be used in motorcycles, powered marine vehicles having an internal combustion engine and can also be used efficiently in the exhausts of domestic and industrial power generators.
Drawings of the Subject Invented Muffler
Uses of the subject invented muffler are illustrated in the following figures.
Figure 1: Usage in a front-engine vehicle
Figure 2: Usage in rear-engine vehicle
The parts in figures are lettered, meaning as follows:
m Engine
e Exhaust pipe
k Catalytic converter
s Muffler
h Air channel
In relation to two models of the subject invented muffler, details are illustrated in the following figures:
Figure 3. A muffler model where the air pump ensuring air suction through venturi is
driven by means of a pulley-belt system from a direct-current electric
motor outside the air channel.
.
Figure 4. An alternative muffler model where the air pump ensuring air suction
through venturi is directly driven by a direct-current electric motor inside
the air channel.
Figure 5. An alternative muffler model where the air pump ensuring air suction
through venturi is driven by a reaction turbine located on the same body but outside the air channel, operated by compressed air.
Explanation of the Subject Invented Muffler
According to Figure 1: If the muffler is located after the catalytic converter right under the engine in a front-engine vehicle, the exhaust pipe from the engine to the muffler will be shortened, thence pre-muffler exhaust-pressure losses will be minimized. If air entry into the muffler is at the vehicle speed but in reverse direction, the muffler will yield an optimum efficiency. Therefore, a Plexiglas air channel must be provided from the front to the rear under the vehicle to ensure a uniform entry of air into the muffler and discharge the gases exiting therefrom.
According to Figure 2: According to Figure 1: If the muffler is located after the catalytic converter right under the engine in a front-engine vehicle, the exhaust pipe from the engine to the muffler will be shortened, thence pre-muffler exhaust-pressure losses will be minimized. If air entry into the muffler is at the vehicle speed but in reverse direction, it will sweep underside of the vehicle. Depending on the vehicle structure, a short Plexiglas channel before the inlet will cause air entry into the muffler to become more uniform.
According to Figures 3.2 and 3.2.1: A high-speed electric motor (1.1) operating with a high-voltage direct-current supply from the vehicle battery produced by using a voltage amplifier makes use of a pulley (1.2) fixed on the motor shaft to transmit its drive to another pulley (1.3) fixed on the air pump shaft via a high-speed and high-temperature resistant V-belt (1.4). It has a head support piece (1.5) to head-fix the electric motor (1.1) and adjust its level to ensure the tightness of V-belt. Another support piece (1.6) in use for the same purpose exists on the base. Support pieces (1.5 and 1.6) are fixed by inert-gas electric welding on the specially manufactured exhaust pipe (3.1) supporting the electric motor and air pump.
According to Figures 3.2 and 3.2.2: The air suction at a high flow rate required for the operation of the subject invented muffler is ensured by means of a double-stage axial fan (2) of air pump at the muffler’s wider end. It ensures an air suction at high flow rate by rotating clockwise constantly and at high speed and it provides for the pressure losses, due to its double-stage feature, caused during the suction of the mixture of exhaust gases and air, and the discharge thereof into the exhaust system and provides the necessary positive pressure therefor as well. It starts when the engine is started and stops when the engine is stopped. These fans (2.3 ad 2.4), which create a pressure stage and are identical, and their hubs (2.1 and 2.2) are interconnected with a shaft (2.5). This shaft is centered by a self-lubricating, high-speed and high-temperature resistant bearings (2.6), which ensure that fans rotate with minimum friction at high speed. The air pump takes drive from the electric-motor pulley (1.2) owing to the pump pulley (1.3) fixed on a shaft.
According to Figures 3.2 and 3.2.3: The specially manufactured exhaust pipe (3.1) that constitutes the main support piece carrying the electric motor and air pump on it is connected to venturi with flange, seal and interconnecting elements (3.2). The guide vanes (3.3 and 3.6) centering and fixing the housing that contains the air pump shaft (2..5) and bearings (2.6) and the pump pulley (1.3) transmitting drive to the axial fan exist in all eight directions. These guide vanes are also used to break the circumferential rotation of the air flow created by the first axial fan (2.1 and 2.3) and convey the air straightly to the second fan (2.2 and 2.4). In order to break the circumferential rotation of the air flow created by the double-stage fan (2) and convey the air straightly along the exhaust pipe, 8 additional guide vanes (3.5) positioned circumferentially at 45 degrees with respect to each other are used. The flow resistance caused by all of these guide vanes put perpendicularly to the flow is negligibly little. Inert-gas electric welding is used to fix guide vanes on the exhaust pipe (3.1) constituting the main support piece and the housing body (3.4) supporting the air pump hub/shaft.
According to 3.2 and 3.2.4: A housing-body (4) having a perforated surface area and containing the elements of an active noise control system, the subject of another patent granted previously to elseone, begins conically (4.1) from a point near the middle of the venturi air suction nozzle (5.1) and then continues cylindrically (4.2). Elements comprising the active noise control system include two microphones and a sound generator. The first microphone measures the main sound intensity and frequency and the noise control unit receiving such data generates a sound of the same intensity but of opposite frequency to ensure that the noise is damped as a result of the interference occurring therebetween. As a result of the measurement made with a second microphone put downstream of air and exhaust gases after the sound generator, a feedback is made to the control unit to ensure a fine adjustment on the sound generator. Due to its shape, the subject invented muffler makes it possible to use such an active noise control system without causing a significant pressure drop in the air and exhaust gas line. An instrument pipe (4.3) projecting out of the perforated body exists to carry out the elements comprising the active noise control system and provide its air tightness. There are two sets of guide vanes (4.4 and 4.5) , each comprising of four vanes located at 90 degrees to each other circumferentially, centering the active noise control system inside the venturi air suction nozzle (5.1) and fixing the conical and cylindrical part of the housing. By keeping the width of these vanes relatively wide, breaking of the circumferential rotation of the air and exhaust flow sucked from the venturi and their further conveyence straightforwardly to the axial fan is ensured. The flow resistance caused by these vanes put perpendicularly to the flow is negligibly small. Inert-gas electric welding is used to fix these vanes on the venturi (5.1) and on the perforated housing body (4).
According to Figures 3.2 and 3.2.5: Air suction created by a high-speed air pump (2) driven by an electric motor (1.1) supplied from the vehicle battery, switching on and off with the start and stop of the engine, respectively, reaches the venturi throat (5.2) through the air suction nozzle of venturi (5.1) and the air velocity rises to the sound velocity in the throat according to Bernoulli Equation for gases. Since the pressure developing in the throat (5.2) at this velocity is theoretically around 0,6 Bar(a), it causes the exhaust gases in the vicinity to be sucked and expand into the venturi suction nozzle (5.1) extensively, which cool down with abundant air taken through the air intake nozzle (5.3 and 5.4) and pushed into the exhaust pipe after passing through the air pump. The quantity of air coming from the air intake nozzle (5.3 and 5.4) in the throat area is 20 times as much the quantity of exhaust gases suctioned from that area. As a result of the cooling and dilution of exhaust gases with this rate of air, the temperature remains below 50 degrees around the air pump to ensure that the downstream active noise control system and air pump unit elements are not exposed to any physical and chemical impact. The venturi (5) , assembled in advance, is inserted into the muffler and vacuum chamber (6) from its larger side and welded onto the muffler and vacuum chamber body (6) at both ends by external inert-gas electric welding. The holes perforated on the throat piece (5.2) are inclined 9 degrees towards the outlet of the throat in order to ease the suction of the exhaust gases at high speeds and avoid the reflection of the sound waves towards the inlet nozzle.
According to 3.2 and 3.2.6: A large quantity of air sucked by an air pump with high flow rate is taken from the venturi throat (5.2). In the meantime, exhaust gases in the vacuum chamber (6.1) around the venturi throat (5.2) are sucked into the center of the throat and thereafter guided towards the venturi air suction nozzle (5.1) with large quantity of air flow. Meanwhile, due to the circumferential and mutually cross interference of the sound frequencies inside the perforated venturi throat (5.2), a substantial reduction in the sound intensity level of the exhaust gases are achieved. The sound intensity of exhaust gases is reduced to a great extent owing to the highly dense stainless steel wool (6.2) wrapping inside the mechanical muffler and vacuum chamber (6.1) circumferentially. Sound waves reflecting from conical surfaces at various frequencies cause frequency interference among them, as well as lose their intensity after entering in the stainless steel wool (6.2) owing to the absorption of sound developing therein. The stainless steel wool (6.2) is wrapped from innnerside with fine stainless steel mesh (6.3) to prevent it from dispersion inside the vacuum medium thereabout. The perforated thick stainless steel sheet (6.4) wrapping around the fine mesh provides an additional drop in the sound intensity by increasing the frequency interference effect of muffler developing in this area, and as well as supports the end plates of the vacuum chamber against negative pressure therein. The mechanical muffler and vacuum chamber body (6.5) is made to withstand the negative pressure developing therein and also stiffened externally. A conical expansion piece (7.2) put right after the entry pipe (7.1) of exhaust gases into the muffler ensures that exhaust gases expand into the vacuum medium and that, thus, sound waves hit conical surfaces to increase the frequency interference effect of the muffler.
According to 4.2 and 4.2.1: The ends of the shaft projecting out of both ends of a high-speed electric motor (1.7) operating with a high-voltage direct current supplied from the vehicle battery using a voltage amplifier enter into the hubs (2.1 and 2.2) of air pump on two sides. The operating principles of this motor are identical to that of the model explained above. It switches on and off with the start and stop of the engine, respectively. However, because it lacks a pulley and belt system and gets drive directly from the electric motor, it has a simpler form. The cables carrying current to this motor are protected by means of an instrument pipe (1.8) present in the air channel. The protection class of this electric motor is IP 54, which secures a smooth operation thereof under exhaust and air conditions. There are 8 guide vanes (3.7) , circumferentially positioned at 45 degrees with respect to each other, that center and fix the direct-current electric motor inside the specially manufactured exhaust pipe (3.1). These guide vanes are used at the same time to break the circumferential rotation of the air flow created by the first stage axial fan ( 2.1 and 2.3) and ensure a linear movement of the air flow upto the second stage axial fan (2.2 and 2.4). In order to break the circumferential rotation of the air flow created by the double-stage fan (2) and convey the air straightly along the exhaust pipe, 8 additional guide vanes (3.5) positioned after the second stage fan ( 2.2 and 2.4), circumferentially at 45 degrees with respect to each other, have been used. The flow resistance caused by these guide vanes put perpendicularly to the flow is negligibly small. Inert-gas electric welding is used to fix these guide vanes on the exhaust pipe (3.1) and on the direct-current electrical motor (1.1).
According to Figures 5.2 and 5.2.1: The part of the exhaust system (8.1, 8.2, 8.3, 8.4) that is connected as flanged to the exhaust systems at inlet (5) and outlet (10), has on it a compressed-air inlet system (8.5, 8.6) and fixed, unmoving guide vanes of the reaction turbine (8.7). The high-flow rate compressed air (app. 3 bar abs) obtained from the compressor or turbocompressor engine air-charge unit of the vehicle selected with a capacity higher than normal or if they are not available, from a compressor unit specially designed for the device subject of this patent, accumulates and stabilizes in the inlet chamber (8.6). The compressed air passing through the guide vanes (8.7) of the turbine that open into this chamber and are distributed circumferentially is guided towards the moving vanes (9.7) of the reaction turbine. All manufacturing processes for the fixed vanes (8.7) of the reaction turbine are precise and the tolerances therefore are highly low. There are 8 guide vanes (8.3) fixed on the specially manufactured exhaust pipe (8.1) circumferentially and positioned at 45 degrees with respect to each other.
According to Figures 5.2 and 5.2.2: The high-pressure and high-flow rate air guided by fixed vanes (8.7) of the reaction turbine rotates moving vanes (9.7) of the turbine and thereby, all the pump elements (9.1 - 9.5) fastened to the same body clockwise with a high velocity. Owing to this, a high-flow suction of air + exhaust gases is ensured from the venturi (5) and discharged outwards through the exhaust pipe. A self-lubricating bearing, resistant to high temperature environment (9.8) externally fitted tight in between the exhaust pipe and the turbo-pump group provides support to the rotation of the turbo-pump group with a minimum friction. The vanes located in the exhaust pipe and there-around are used to break the circumferential rotation of the air current created by the first axial fan (9.2, 9.4) and convey the air straightly to the second fan (9.3, 9.5). The fans located at both ends of the air pump set are fixed on the rotating fan body (9.1) at the same angular position and their speed of rotation is the same as that of the reaction turbine. All manufacturing processes carried out on the turbo-pump body (9.6) are precise and the tolerances therefore are highly low.
According to Figures 5.2 and 5.2.3: The high-pressure and high-flow air expanding in the reaction turbine (8.7, 9.7) causes the turbo-pump group to reach high speeds of revolution and then arrives in the turbine expansion chamber (10.1) with a reduced pressure (1.02 bar abs). This chamber opens through a partly perforated exhaust pipe inside it (10.2) into the milieu of high-velocity and high-flow air + exhaust gases, and the air is thus suctioned through the chamber outwards. An extension of this pipe (10.3) enters the body of turbo-pump group with a very small diametral tolerance and provides during a fast rotation of the group, a frictionless tightness between the pipe outside and the chamber. In order to break the circumferential rotation of the air current created in the exhaust pipe in this section by the double stage fan (9) and convey the air straightly along through the exhaust pipe, 8 additional guide vanes positioned circumferentially at 45 degrees with respect to each other (10.4) are used. The exhaust pipe extension lying up to the end of the vehicle is welded onto or slip-fitted on the end of this part.
