Title of Invention

"IMPROVED AIR FILTER FOR INTERNAL COMBUSTION ENGINES"

Abstract

The present invention relates to an improved filter device which works on the principle of centrifugal action of air by creating a cyclone effect is created within the assembly as a result of which over 96% of the contaminants which are sucked into the assembly are expelled back into the atmosphere, the device comprising in essence consists of a combination of the main filter element, safety cartridge and dust unloader alongwith a turbo system consisting of a fan assembly mounted in a manner such that it strikes the air at an angular direction causing the cyclonic effect for outward expulsion of the contaminants and dust.

Full Text

IMPROVED AIR FILTER FOR USE WITH INTERNAL COMBUSTION ENGINES. BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an improved air filter for internal combustion engines. More particularly, the present invention relates to an improved air filter device for providing filtered air to an internal combustion engine. More particularly, the present invention relates to an improved air filter device for providing filtered air to vehicles such as trucks and tractors, which operate in dusty conditions and environment such as on farms and agricultural lands. Description of the Related/Prior Art Air filters and air cleaners for providing filtered air to an internal combustion engine are well known in the/art. In one type of filter, a housing is provided having an air inlet at its small and an air outlet at its large end for directing flow of air into and out of the housing. The housing houses the actual air filter device which has a filter element coaxially arranged to the interior of the housing. The filter device fits within the housing. Generally, the filter device has a cylindrical or frusto conical shape. As will be readily apparent, the diameter upstream is smaller than the diameter downstream in case of frusto conical shaped filter devices. The base of the filter includes a flat ringj which is received within the housing and is sealably engaged with the housing. The filter element generally includes a series of circumferentially arranged pleats. By directing airflow between the pleats a distance axially before passing though the filter, the efficiency and capacity of the air filter is increased and the pressure drop decreased. By evenly distributing airflow, all of the filter media is used. It is known that additional filter area will increase the filtering capability and will lower the average air flow face velo'clty. The radial dimension of the filter at the base ring is, however, limited because of the size of the housing. Additionally, as the radial dimension or width of the pleat increases, it is less rigid and more prone to vibration. The prior art also teaches filtration devices including wire mesh and oil bath. These filter devices dispensed with paper altogether. These types of filter devices have not been found effective in dusty conditions due to the inability of oil and mesh to prevent passage of dust therethrough. As a result, a paste of oil and dust would get carried to the engine damaging the engine system. An improved filtration system is disclosed in the prior art, which envisages a series of filtration steps involving pre-cleaners, oil, wire mesh and paper element. While such systems were more effective as compared to a mere oil and mesh system, they still left a lot to be desired because of their low dust holding capacity. Such filters also suffered from a major disadvantage of low filter life due to oil carry over and wetting of the media by oil. The oil carry over would also clog the pores of the filter and choke it resulting in a very low dust holding capacity. As a result of clogging, the filters would require replacement even before the normal first service period rendering them undesirable and unsuitable for use in vehicles plying in dusty conditions. The prior art also teaches several forms of dry type air filters. Unfortunately, these filters are suitable for only light to medium dust conditions. Some filters also envisage a secondary element, referred to as 'safety cartridge' and normally made of non-woven felt media. The safety cartridge serves the function of filtering the air when the main filter is punctured or is removed for cleaning. The safety cartridge, while offering additional advantage, also causes an increased resistance. The main filter consists of a filter element made of conventional medium such as CRS end caps bonded to the paper media through adhesive. The main element consists of end caps on both sides made of cold rolled sheet. A rubber gasket is provided on both end caps as a sealant to prevent metal to metal contact between the housing and the end cap. Again, the main filter media has a limited dust retaining capacity and the customer has the responsibility of removing and cleaning the main element from the housing at regular intervals. Also, every time the main element was removed for cleaning, it would invariably necessitate change of gaskets to retain proper sealing. US patent No. 5,522,909 seeks to overcome the above-mentioned disadvantages by providing an air filter device which would fit within a housing having an air inlet for receiving unfiltered air and an outlet to supply filtered air to an engine. The air filter device includes a flat, closed top substantially perpendicular to the axis of the device. An open base is axially aligned with the flat top and has an interior diameter larger than the diameter of the top. Extending between the flat top and the open base is frusto conical filter media. The filter media is arranged in the form of a plurality of circumferentially spaced primary or first pleats. In one embodiment, the radial depth or width of each primary or first pleat is greater near the flat top than at the open base. Each primary pleat has an interior edge and an exterior edge. Each interior edge has a greater angle to the frusto conical axis than the angle to the frusto conical axis of each exterior edge. A series of inverted, secondary pleats are interspaced between the primary pleats. The secondary pleats are reversed in orientation to the primary pleats. The secondary pleats have their greatest depth at the open base and gradually taper to a zero depth toward the flat top. While the filter envisaged by the US Patent overcame the disadvantages of the prior art to a large extent, it made it impossible for the filters to be removed and serviced. Therefore, at period intervals, not only the main filter element, but the entire filter assembly including the housing required replacement, thereby rendering this type of filters uneconomical. Another improvement in the prior art filters, which sought to avoid periodical servicing, envisages a dust unloader. The main function of the dust unloader was service-free removal of the dust extracted in the precleaning stage. These type of filters were of high utility in the removal of light dust, for example those occurring in the agricultural sector without the cumbersome process of servicing. The dust unloader, normally made of nitrile rubber is mounted at one end inside the housing with the other end being connected to an ejector. Normally, the ejector is mounted on the exhaust pipe downstream from the silencer. In yet another filter taught by the prior art, the filter device included a dust collector or a bowl. The dust collector had a tapered configuration to allow the dust particles to get collected and settle down. It also included a precleaner having a cylindrical tube consisting of stationery fins attached to the inner periphery of the tube. In such a construction, upon ignition of the engine, the air containing dust particles would travel into the precleaner from where it would be guided in one particular direction after striking the stationery fins. From the precleaner, air would travel to the opening of the dust collector. Because of the tapered configuration of the dust collector, a centrifugal force of action would develop causing the air to swirl and drop the dust particles to fall and collect in the dust collector. The problem with this kind of construction was that the swirling action would actually cause only the heavy dust particles to fall in the dust collector and the lighter particles would still travel to the engine thereby reducing the overall efficiency of the system to about 80%. The prior art also teaches several wet type filters especially for machinery operating in relatively clean air. In such constructions, the air drawn into the filter flows through a packing wetted with oil and made of woven cloth, expanded metal or knitted steel mesh. The dust particles are deposited on the oil wetted surface of the filter packing. The main disadvantage of the wet type filters was that they posed installation difficulties. These filters had to be installed in such a way that the extracted dust is not shaken into the clean side. It was also necessary to ensure that these filters were always shielded from rain and other sources of water. Another problem with the wet type filters was that the dust trapped therein would not always be visible thereby leading to neglect in servicing. Servicing is normally carried out by washing with diesel fuel or with stream-jet cleaner. However, any neglect in the servicing caused serious impairment of filter action, leading to premature wear of the assemblies connected downstream of the filter. Objects of the invention It is therefore, a primary object of the present invention to provide a filter device for use with internal vehicles operating in a dusty conditions, which avoids all the disadvantages of the prior art. It another object of the present invention, which ensures complete removal of dust regardless of the dust holding capacity of the filter element. It is a further object of the present invention to provide a filter device, which minimises servicing without in any way adversely affecting the performance of the filter. It is yet another important object of the present invention to provide a filter device that will maximizes the amount of filter area in a given housing space. It is still another important object of the present invention to provide a filter device that maximises axial air flow and minimises air flow change in direction. It another important object of the present invention to provide a filter device that expels all the dust collected in the process of the present invention. Summary of the invention The above and other objects of the present invention are achieved by the improved filter device of the present invention, which works on the principle of centrifugal action of air. The construction of the improved filter device is such that cyclone effecf is created within the assembly as a result of which over 96% of the contaminants which are sucked into the assembly are expelled back into the atmosphere. The improved filter assembly of the present invention, in essence consists of a combination of the main filter element, safety cartridge and dust unloader of the prior art alongwith a turbo system consisting of a fan assembly mounted in a manner such that it strikes the air at an angular direction causing the cyclonic effect for outward expulsion of the contaminants and dust. Accordingly, the present invention provides an improved filter device for use with vehicles which comprises a housing having end caps, an primary filter element coaxially mounted within said housing and bonded to said end caps, a safety cartridge placed contiguous To said in said housing and bonded to said end caps, means for unloading contaminants captured by said primary filter element, said unloading means extending from said housing to unload the contaminants, a dust collector means located at the base of the housing and an air turbine means having at least two rotatable blades mounted in said bowl such that upon ignition of the engine, the air containing contaminants would strike said rotatable blades in an angular direction causing them to rotate and develop a centrifugal force of action for expelling the contaminants in said back into the atmosphere. The filter device of the present invention has an overall efficiency of about 96% even in highly dusty conditions. The primary advantage of the invention is that the dust particles are not allowed to settle inside the filter assembly, but are expelled out instantaneously. Unlike prior art constructions, the centrifugal force generated by the rotatable blades expel not only heavier particles but also lighter particles. Detailed description The most important consideration in the choice of an air filter is that it should have sufficient protection against wear under all possible dust conditions. In other words, the extraction efficiency of the filter must be such that, an engine fitted with the filter should demonstrate uniform pattern of wear regardless of the intensity of the dust conditions in the environment. In order to able to translate the dust holding capacities obtained on a test rig into hours of operation or kilometers of driving, it important to understand the dust concentration levels of the operating environment. After prolonged study, the following data has been compiled with the values being dust concentration mean values obtained through intake ducts at 1 to 1.5m above the ground : Mean dust concentration in [mg/m cube] 1. Trucks in normal European traffc 0.6 2. Trucks in non European traffic 3.0 3. Off- road trucks (construction sites) 8.0 4. European road traffic 5.0 5. Non European road traffic 30.0 6. Construction machinery 35.0 7. Agricultural Machinery in European area 5.0 8 Agricultural Machinery in non European area 15.0 The size of the air filter is also an important criteria and primarily depends on the maximum air requirement of the engine. The air requirement can also be determine:d from the engine data, i.e., swept volume, rotational speed and volumetric efficiency using the following equation: 4-stroke engines "Air requirement = Swept Volume . Rotational speed.Volumetric efficiency (2 X 1000) 2-stroke engines Air requirement = Swept Volume . Rotational speed. Volumetric efficiency (1 X 1000) The dry air filter, in which category, the device of the present invention falls have to meet a high extraction efficiency. Also known as service life, it can be defined in terms of the quantity of dust taken up by the filter within a given increase in air flow resistance. The service life of the air filter can also be defined in terms of the number of hours for which the filler is put into operation and may be described by the following equation: Hrs. of operation = Laboratory dust capacity (g) . 1000 Dust flow concentration(mg/m cube) . Air Flow Rate m cube /min . 60 The filter device of the present invention demonstrates at least 96% overall efficiency in all operating conditions. The device of the present invention is an improvement over the prior art dry air filters in that it retains the advantages offered by the latter at the same time obviating its disadvantages. In essence, the filter device of the present invention comprises of a housing. A primary filter element is coaxially mounted within said housing. In the preferred embodiment, the primary filter element may be a conventional filtering media such as a filter paper. Preferably, the filter paper may be pleated to offer greater filtering properties. Contiguous with the primary filter element is a secondary filter element or a safety cartridge. Preferably, the safety cartridge is made of a non-woven felt medium. Extending from the housing is a dust unloader employed for service free removal of dust extracted in the precleaning stage. In a preferred embodiment the dust unloader is made of nitrile rubber. The dust unloader may conveniently be installed in any position with respect to the housing. If the outlet pipe of the dust unloader points upwards, it can be fitted with a cap that prevents the rainwater from entering the main housing when the engine is switched off. The connection line between the filter and the dust unloader is preferably as short as possible without any tight crimps or bends to avoid increased flow resistance. A dust collector is installed at the appropriate position in the housing, preferably in the base. Within the dust collector is mounted a air turbine means. The air turbine means consists of a plurality but at least two rotatable blades. The dust collector is provided with a slot on the periphery thereof to provide a path for the expulsion of the contaminants into the atmosphere. In a preferred embodiment, a bottom of the bowl is provided with a cap means to protect the device from the rainwater. In the conventional air filters suffered from the major disadvantage of rainwater seeping into the assembly, wetting the filter element and many instances, causing it to burst. The additional cap means effectively obviates this problem. In another preferred embodiment, the bottom face of the dust collector is provided with uniformly spaced projections to increase the resistance of the dust collector face against fatigue failure. Otherwise, due to the centrifugal forces generated due to the rotation of the blades of the air turbine means, the bottom face of the dust collector could develop stress leading to fatigue failure. In another preferred embodiment, a precleaner means is installed in the dust collector. The precleaner of tubular construction is provided with one or more stationary fins. The fins are normally mounted at an angle of 30° with respect to the horizontal axis of the dust collector and spot welded. The air turbine means, which may also be referred to as a fan assembly, is preferably mounted in the dust collector by means of a nylock nut. Preferably, the fan assembly consists of four rotatable blades connected to each other on a common shaft by means of nuts and washers. The fan assembly is mounted in the dust collector in such a way that the centrifugal force generated by the rotation of the fan blades would cause uniform and unimpeded expulsion of the dust particles through the slot provided therefor in the dust collector. The present invention will now be described in a greater detail with reference to the accompanying drawings in which: FIG. 1 is a sectional view of a conventional air filter device taught by the prior art; FIG. 2 is a sectional view of one embodiment of an air filter and air cleaner device constructed in accordance with the present invention; FIG. 3 is an alternate embodiment the present invention; FIG. 4 is an elevational view of the air filter and air cleaner device shown in FIG. 3; FIG. 5 is an exploded view of the precleaner assembly of the present invention; FIG. 6 is an exploded view of the fan assembly of the present invention. FIG.7 is a sectional view of the air cleaner and air filter device taken along section line X-X of FIG. 4 showing the construction of various parts within the housing; Referring to Figure 1, in the conventional filter systems, the mail element 2 made of synthetic media does the overall filtration. The dust unloader 4 is connected to the main housing 1 by means of one or more clamps. During the operation of the machine, the left over contaminant at the end of the first filtration is shifted into the dust unloader 4 for further filtration. The main element 2 is provided with a reinforcing means normally a center tube 5 for the purpose of providing strength thereto. The main housing comprises a bottom part 1' and a top cover part 1" connected by means of a plurality of wire clamps 3. As mentioned above in the background to the invention the problem with this kind of construction was that the swirling action would actually cause only the heavy dust particles to fall in the dust collector and the lighter particles would still travel to the engine thereby reducing the overall efficiency of the system to about 80%. Referring now to figure 2, the pre cleaner assembly 1 is connected to the main housing by means of a plurality of clamps 10. The pre cleaner assembly comprises of a dust collector 1' provided with at least one slot 1" on the periphery thereof for the expulsion of the contaminants into the atmosphere. The main housing is provided with a conventional primary filter element 4, a secondary safety cartridge 6 preferably made of felt media and a dust unloader 13 as depicted. The primary filter element 4 absorbs a certain proportion of the contaminants. The pre cleaner assembly is held on to the main housing by one or more adhesive means 10. Such adhesive means are preferably worm clamps 10. The contaminant laden air is sucked into the dust collector by means of opening 21 provided at the bottom of the dust collector. However, heavy and light particles of the contaminants are impelled above in a cyclone effect by means of one or more fins located intermediate to the bowl and the main housing. The said one or more fins are designed such that the contaminant particles strike the blades of the turbine fan assembly 6' at a specific angle and at a specific velocity. The specific angle and velocity of the dust particles result in the expulsion of the dust contaminants from the slot 1" into the atmosphere, the turbine fan assembly consists of a plurality of blades held together by means of a washer 18 and a nylock nut. Figure 3 is a depiction of an alternate embodiment of the present invention wherein an additional secondary filter element 8 in the form of a safety cartridge is incorporated into the main housing. The function of the secondary filter element is to ensure a greater degree of protection to the engine in the event of a puncture or tear in the primary filter element 3. In the course of operation, occasionally due to very heavy contaminant particles, the primary filter element 3 is subject to tearing. This results in the dust particles settling down in the engine and resulting in additional wear and tear thereby reducing the life of the engine. The secondary filter element 8 helps as an additional absorber to absorb contaminant particles even in cases of damage to the primary filter element 3, till such time as the primary filter element 3 can be replaced. Additionally, the secondary filter element 8 helps enhance the performance of the filtration in cases wherein the nominal flow rate is higher than 4.5 m cube/min. The secondary filter element is preferably made of non-woven felt media wrapped around a center tube 4 made preferably of plastic such as PPT 20. The secondary filter element may be located at any position inside the main housing but is ideally located at the inner periphery of the primary filter element 3. Figure 4 is an elevational view of the alternate embodiment of the invention as depicted in figure 3. An elbow 3 is mounted on the top cover of the main housing 1. The elbow is preferably made of rubber (preferably EPDM) and is connected at one end thereof to the top cover of the housing by means of wire clamps. The other end of the elbow is mounted to the opening face of the bracket means which is in turn connected to the engine suction means (not shown in the figure) The dust unloader 2 is mounted at the bottom cover of the main housing 1. Figure 5 is an explode view of the pre cleaner assembly of the invention. The pre cleaner assembly consists of a bowl 3 provided with at least one or more pleats or fins 1 connected thereon at the open end thereof. A fan assembly 4 is provided internally in the bowl 3. The fan assembly consists of at least one blade 4'. The bowl 3 is also provided with at least one slot 6 to enable the expulsion of contaminants through the slot 6 on propulsion by the blade 4' of the fan assembly 4. The said one or more pleats or fins are provided at specific angles as a result of which the contaminant particles achieve a specific velocity. On striking the fan blades, the dust particles are expelled out of the slot 6. While multiplicity slots may be provided on the bowl 3, optimum performance is obtained by only one slot. Providing a multiplicity of slots results in a reduction in the efficiency of expulsion due to interparticle collision. Heavier contaminant particles may chose alternate escape routes thereby interfering with the expulsion of light or very light contaminant particles. Preferably, the pleat or fin angle is 30°. Referring now to figure 6 of the drawings, the fan assembly consists of a fan body 1 provided with at least one fan blade 1'. The fan blades 1' are interconnected by means of shaft 7, nut 4 and washer 5. The fan assembly is connected to the bowl through a series of washers and a nylock nut 6. The fan assembly results in the creation of a centrifugal force which in turn rotates the blades resulting in substantial expulsion to the order of 96 % of the contaminant particles. Referring now to figure 7, a sectional view of the device of the invention along the section line X - X is shown along with the construction of the various parts. The function of the safety cartridge which acts as the secondary safety element 2 and the primary safety element 1 as well as the dust unloader 3 and the central tube 'are as explained above. It must however be understood that the invention is not limited to the embodiments represented in the accompanying drawings. Various modifications are possible to the device within the spirit of the present invention and are included in the scope of the present invention. We claim: 1. An improved filter device for Internal combustion engines which comprises a housing having end caps, a primary filter element coaxially mounted within said housing and bonded to said end caps, a safety cartridge placed contiguous to said primary filter element in said housing and bonded to said end caps, means for unloading contaminants captured by said primary filter element, said unloading means extending from said housing to unload the contaminants, a dust collector located at the base of the housing and having slot in the periphery thereof for the expulsion of said contaminants, and an air turbine having at least two rotatable blades mounted in said dust collector such that upon ignition of the engine, the air containing contaminants will strike said rotatable blades in an angular direction causing them to rotate and develop a centrifugal force of action for expelling the said contaminants back into the atmosphere. 2. A filter device as claimed in claim 1, wherein said primary filter element comprises a conventional filtering media, such as a filter paper. 3. A filter device as claimed in claim 1 or 2 wherein, a secondary filter element is mounted within said dust collector contiguous with said primary filter element. 4. A filter device as claimed in claim 3 wherein said secondary filter element comprises a safety cartridge. 5. A filter device as claimed in claim 4 wherein said safety cartridge is made of non woven felt medium. 6. A filter device as claimed in claim 1 wherein said dust unloader and said dust collector are equipped with a cap for preventing rain water from entering the main housing when the engine is switched off. 7. A filter device as claimed in any preceding claim wherein the air turbine comprises four rotatable fan blades. 8. A filter device as claimed in any preceding claim wherein the bottom face of the dust collector is provided with uniformly spaced projections to increase the resistance of the dust collector face against fatigue failure. 9. A filter device as claimed in any preceding claim wherein a precleaner is located in the dust collector. 10. A filter device as claimed in claim 8 wherein said precleaner is of tubular construction. 11. A filter device as claimed in claim 10 wherein said precleaner is provided with one or more stationary fins. 12. A filter device as claimed in claim 11 wherein said stationary fins are mounted at an angle of 30° with respect to the horizontal axis of the dust collector. 13. A filter device as claimed in any preceding claim wherein said air turbine is mounted in the dust collector by means of a nylock nut. 14. ^An improved filter device for use with internal combustion engines substantially as herein described with reference to and as illustrated in the accompanying drawings.

Documents:

536-del-2001-abstract.pdf

536-del-2001-claims.pdf

536-DEL-2001-Correspondence-Others (11-02-2010).pdf

536-del-2001-correspondence-others.pdf

536-del-2001-correspondence-po.pdf

536-del-2001-description (complete).pdf

536-del-2001-drawings.pdf

536-DEL-2001-Form-1-(11-02-2010).pdf

536-del-2001-form-1.pdf

536-del-2001-form-19.pdf

536-DEL-2001-Form-2-(11-02-2010).pdf

536-del-2001-form-2.pdf

536-DEL-2001-Form-26-(11-02-2010).pdf

536-del-2001-form-3.pdf

536-del-2001-form-4.pdf

536-del-2001-gpa.pdf