Claims:We claim:

1. An oil bath-type air-filter assembly (150) with controlled oil pull-over, said air-filter assembly (150) comprises:

• a filter housing (110);

• an oil reservoir (120) disposed below said filter housing (110) and connected thereto;

• an air intake pipe (130) having an inlet end (132) connected above said filter housing (110) and outlet end (134) disposed above the surface of oil in said oil reservoir (120);

• an air outlet pipe (140) to supply filtered clean air;

• a bowl (122) immersed in said oil and fixed above the bottom surface of said oil reservoir (120), the axis of said bowl (122) aligned with the axis of said air intake pipe (130);

• an upper wire mesh filter (142) and a lower wire mesh filter (144) with a spacer (144) disposed therebetween; and

• a dry filter element (148) disposed inside said housing (110) and surrounding said intake pipe (130) and disposed above said upper wire mesh filter (144);

wherein at least one through hole (136) in at least one row is provided in the periphery of said air intake pipe (130), said through hole (136) disposed parallel to the bottom of said housing (110) for bypassing a predefined amount of fresh air (AF) to be mixed with returning air (AR), for reducing the oil pull-over of the mixed, filtered and cleaned air before supply thereof.

2. Oil bath-type air-filter assembly (150) as claimed in claim 1, wherein said inlet end (132) of said air intake pipe (130) opens outside and/or above said housing (110) and said outlet end (134) of said air intake pipe (130) opens above the surface of oil in said oil reservoir (120);

3. Oil bath-type air-filter assembly (150) as claimed in claim 1, wherein said filter assembly (150) comprises at least three rows (138) of said through holes (136).

4. Oil bath-type air-filter assembly (150) as claimed in claim 3, wherein one of said rows (138) each is respectively disposed above said upper wire mesh filter (142) and below said lower wire mesh filter (144) and between said upper and lower wire mesh filters (142, 144).

5. Oil bath-type air-filter assembly (150) as claimed in claim 1, wherein said spacer (146) is an annular spacer disposed between the outer peripheral edges of said upper and lower wire mesh filters (142, 144).

6. Oil bath-type air-filter assembly (150) as claimed in claim 3, wherein said holes (136) have a diameter in the range of 15 to 20 mm.

7. Oil bath-type air-filter assembly (150) as claimed in claim 1, wherein the maximum oil pull-over permissible by said air-filter assembly (150) is in the range of 0.2 to 0.3% by weight of the oil present in said oil reservoir (120).

8. Oil bath-type air-filter assembly (150) as claimed in claim 1, wherein said filter assembly (150) comprises:

• a vertically disposed elongated filter housing (110);

• an oil reservoir (120) connected below said filter housing (110);

• an air intake pipe (130) disposed inline within said housing (110); said air intake pipe having the inlet end (132) thereof opening outside and/or above said housing (110) and the outlet end (134) thereof opening above the oil surface of said oil reservoir (120) inside said housing (110);

• an air outlet pipe (140) to supply filtered clean air;

• a first annular chamber (112) formed between the inner walls of said housing (110) and the outer shell of said dry filter element (148), said chamber laterally connected via an outlet pipe (140) to supply filtered clean air;

• an oil-splash reducer conical bowl/cup (122) fixed above the bottom surface of said oil reservoir (120), the axis of said bowl (122) aligned with the axis of said air intake pipe (130); and

• a pair of wire mesh filters (142, 144) spaced apart from each other by means of an annular spacer (144) to form a second annular chamber (114) therebetween; and

• a dry filter element (148), preferably formed as a paper filter cartridge disposed inside said housing (110) and surrounding said intake pipe (130) above said upper wire mesh filter (144);

wherein a plurality of rows (138) of through holes (136) are drilled through the periphery of said air intake pipe (130), said through holes (136) disposed parallel to the bottom of said housing (110) for bypassing a small amount of fresh air (AF) to be mixed with returning air (AR) within said housing (110) for reducing the oil pull-over of the mixed, filtered and clean air before supply thereof.

9. Oil bath-type air-filter assembly (150) as claimed in claim 8, wherein said filter assembly (150) comprises at least three rows (138a, 138b, 138c) of said through holes (136) on said air intake pipe (130).

10. Oil bath-type air-filter assembly (150) as claimed in claim 9, wherein at least one of said rows (138a, 138b, 138c) each is respectively disposed within said first chamber (112) disposed above said upper wire mesh filter (144), said second chamber (114) disposed in between said lower and upper wire mesh filters (142, 144), and a lower portion (116) of said housing (110) disposed below said lower wire mesh filter (144).

Dated this 11th day of September 2019.

Digitally Signed.

(SANJAY KESHARWANI)
APPLICANT’S PATENT AGENT
REGN. NO. IN/PA-2043. , Description:FIELD OF INVENTION

The present invention concerns air filters used in automobiles including agricultural tractors. In particular, the present invention relates to oil-bath type air filters widely used in automobiles including agricultural tractors. More particularly, the present invention relates to oil-bath type air filters, for example oil-bath type air filters of automobiles including agricultural tractors which exhibit substantially reduced oil-pull over during the engine operations thereof.

BACKGROUND OF THE INVENTION

Automobiles including agricultural tractors often operate in extremely dusty conditions and the internal combustion engines thereof require a continuous flow of clean air for optimum combustion therein. Accordingly, an air breathing/cleaning device, more commonly known as air filter is provided to remove any particulate matter suspended in the fresh air being sucked through the air intake pipe leading to engine.

This air-filter is designed to remove suspended contaminants present in this incoming fresh air for cleaning it before thereof suction into the engine.

One of the important categories of air-filters include oil-bath type air filters widely used in automobiles including agricultural tractors. These oil-bath type air filters are configured like a can which consists of an oil reservoir/cup to hold oil therein and a body resting thereon. Both these parts of air filter are clamped/screwed together.

Thereafter, air-filter assembly is either mounted and directly attached on top of the carburetor or is mounted separately and connected to the carburetor by means of hoses or tubing.
During engine operation, due to engine suction, a vacuum is created in the air-filter body and fresh air entering through the air-intake pipe is forced down vertically into the oil reservoir. Once this incoming fresh air reaches and hits the bottom of the oil reservoir, the direction of motion of this air stream is reversed abruptly and air is forced up in the air-filter body to be sucked into the intake system of the engine.

This sudden change of direction is easy for the air mass, but these particulates or suspended dust particles or other foreign matter present in the incoming fresh air flow are not efficient enough to abruptly change the direction thereof with this air mass and therefore, these particles are caught trapped in the oil present in the oil reservoir.

This is the basic structure and function of a conventional oil-bath type air filter. Due to a low-maintenance and operating costs of such oil-bath type air-filter, these are quite popular and versatile in automotive engines operating in dusty environments, such as earth work and mining equipment/agricultural tractors.

PRIOR ART

Publication No. US 2835338 A titled: “Liquid bath air cleaner” relates to the field of liquid bath air cleaners for use with internal combustion engines and the primary object of this invention is a new and improved liquid bath air cleaner with a generally upright rectangular/circular housing having an air path with a dirty air inlet and a clean air outlet, a filter element in the air path in the housing, a liquid sump cup removably attached to the lower end of the housing to provide a liquid pump and having normal liquid level, a seat on the housing for the cup, manually operable attaching means for detachably connecting the sump cup to the housing in engagement with the seat, a bail-type mechanism associated with the sump cup and housing for supporting the cup in substantial spaced relation to the housing out of engagement with the seat, means on the cup to engage the said bail-type mechanism when the manually operable attaching means is detached so that the sump cup will be held in said substantial speed relation to the housing, such bail-type mechanism being pivoted to the housing and movable between operative and inoperative positions and constructed so that when the attaching means is detached and the bail-type mechanism is in its operative position, it will support the cup in said substantial spaced relation to the housing so that liquid from the filter element and housing may drain back into the cup, but when the bail-type mechanism is in its inoperative position, the sump cup may be completely detached and removed from the housing.

Although, above prior art discloses a dry filter element, the object of the same is not to control of oil pull over therein.

DISADVANTAGES ASSOCIATED WITH THE PRIOR ART

However, there is a serious disadvantage associated with such oil-bath type air-filters, which is that although now air is sucked into the engine substantially free of harmful particulate matter, this cleaner air also carries along with it a substantial quantity of oil from the oil reservoir into the engine. This oil carried by cleaner air sucked into the engine is called “oil pull over”.

This “oil pull-over” phenomenon leads to increased oil residue and contamination on the pistons, intake and exhaust manifolds, fuel injectors and valves, and thus results in increased emissions and reduced oil economy.

Normally, this oil pull-over is more than 1% by weight of the oil present in the oil reservoir of the air-filter. Until now, there was not stipulations relating to this “oil pull-over” for automobile manufacturers.
This oil pull-over phenomenon along with filtered clean air supplied to engines often leads to considerable increase in oil residue and contamination on the pistons, intake and exhaust manifolds, fuel injectors and valves, and thus results in increased emissions and reduced oil economy.

However, with the continuous environment degradation, and challenges posed thereon due to the ever-rising greenhouse effects by continuously increasing pollution, such oil pull-over in air-filters for diesel engines to be limited as low as possible.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide a low-cost and simple oil-bath type air-filter for automobiles working in contaminated or dusty conditions.

Another object of the present invention is to provide an oil-bath type air-filter for automobiles such as agricultural tractors which is easy to maintain.

Still another object of the present invention is to provide an oil-bath type air-filter for agricultural tractors which is small in size.

Yet another object of the present invention is to provide an oil-bath type air-filter for agricultural tractors has low oil pull-over.

A further object of the present invention is to provide an oil-bath type air-filter for agricultural tractors which reduces the pressure drop without increasing the air-filter size thereof.

A further object of the present invention is to provide an oil-bath type air-filter for agricultural tractors which reduces pressure drop within air-filter even without increasing the size thereof.

These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF INVENTION

In accordance with the present invention, there is provided an oil bath-type air-filter assembly with controlled oil pull-over, the air-filter assembly comprises:

• a filter housing;

• an oil reservoir disposed below the filter housing and connected thereto;

• an air intake pipe having an inlet end connected above the filter housing and outlet end disposed above the surface of oil in the oil reservoir;

• an air outlet pipe to supply filtered clean air; and
• a bowl immersed in the oil and fixed above the bottom surface of oil reservoir; the bowl axis aligned with the axis of the air intake pipe;

wherein at least one through hole is provided in the periphery of the air intake pipe, the through hole disposed parallel to the bottom of the housing for bypassing a predefined amount of fresh air to be mixed with returning air for reducing the oil pull-over of the mixed, filtered and cleaned air before supply thereof.

Typically, the inlet end of the air intake pipe is disposed outside and/or above the housing and the outlet end of the air intake pipe is disposed open above the surface of oil in the oil reservoir;

Typically, the filter assembly comprises at least three rows of circular holes.

Typically, one of the rows of the plurality of holes is disposed above the upper wire mesh filter and the lower wire mesh filter each and a middle row of the plurality of holes is disposed between the upper wire mesh filter and the lower wire mesh filter.

Typically, the spacer is an annular spacer disposed between the outer peripheral edges of the upper wire mesh filter and the lower wire mesh filter.

Typically, the holes have a diameter in the range of 15 to 20 mm.

Typically, the maximum oil pull-over permissible by the air-filter assembly is in the range of 0.2 to 0.3% by weight of the oil present in the oil reservoir.

Typically, the filter assembly comprises:

• a vertically disposed elongated filter housing;

• an oil reservoir connected below the filter housing;

• an air intake pipe disposed inline within the housing; the air intake pipe having the inlet end thereof disposed outside and above the housing and the outlet end thereof opening inside the housing and disposed above the oil surface of the oil reservoir;

• an annular chamber formed between the inner walls of the housing and the outer shell of the dry filter element; the chamber laterally connected via an outlet pipe to supply filtered clean air;

• an oil-splash reducer bowl/cup placed above the bottom surface of the oil reservoir centrally aligned with the outlet end of the air intake pipe;

• a pair of wire mesh filters spaced apart from each other by means of an annular spacer;

wherein a plurality of rows of through holes are drilled through the periphery of the air intake pipe, the rows of holes are made parallel to the bottom of the housing for bypassing a predefined amount of fresh air to be mixed with returning air for reducing the oil pull-over of the mixed, filtered and cleaned air before supply thereof.

Typically, the filter assembly comprises at least three rows of the circumferential holes made on the air intake pipe.

Typically, at least one row each of the at least three rows the through holes is disposed within a respective portion of the housing, preferably the portion disposed above the upper wire mesh filter, the portion below the lower wire mesh filter and the middle portion disposed in between the lower and upper wire mesh filters.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described in the following with reference to the accompanying drawings.

Figure 1 shows a front cross-sectional view of the conventional air-filter for an automobile operating in contaminated environment, such as an agricultural tractor.

Figure 2 shows a front cross-sectional view of the air-filter for an automobile operating in contaminated environment, such as an agricultural tractor, which is configured manufactured in accordance with the present invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, an oil bath-type air-filter with controlled oil pull-over effect, for example in oil-bath type air filters of an automobile engine operating in dusty conditions, such as a tractor engine and configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention.

Figure 1 shows a front cross-sectional view of the conventional air-filter 50, for example of an automobile operating in contaminated environment, such as an agricultural tractor. The oil filter 50 comprises a housing 10 mounted on an oil reservoir 20. An intake pipe 30 is configured with two open ends 32, 34. The upper end 32 of intake pipe 30 allows the entry of fresh air A into oil-filter housing 10 and is attached on top thereof. The other end 34 of intake pipe 30 is disposed slightly above the oil level in oil reservoir 20. A lateral opening 12 is provided near the upper portion of housing 10, which is connected to an outlet pipe 40 to supply substantially cleaner filtered air A+ to engine E of the automobile, e.g. agricultural tractor engine. Two primary wire mesh filters 42, 44 are disposed in the middle portion of housing 10, which are mutually separated by a spacer 48, preferably made of rubber. This rubber spacer 48 maintains a predefined distance between two primary wire mesh filters 42, 44. A secondary dry filter element 46 made of paper cartridge is disposed above the upper wire mesh filter 42. The intake air A passes through intake pipe 30, strikes the oil in oil reservoir 20 and returns towards wire mesh filters 42 and after passing through the wire mesh filters 42, 44, this returned air subsequently enters the dry filter element 46 before being supplied to the internal combustion engine E, e.g. of an agricultural tractor. The oil reservoir 20 is preferably provided with a bowl/cup 22 resting on the bottom thereof, which is centrally disposed below the lower open end of intake pipe 34. This cup/bowl 22 reduces the probability of splashing of oil due to high-velocity air striking the surface of oil present in oil reservoir 20. Oil reservoir is joined below the housing 10, preferably by welding or screwing. Fresh air A, which is often excessively contaminated in dusty operating conditions of the automobile, e.g. agricultural tractor, entering through first end 32 of intake pipe 30 is released at other end 34 thereof, whereby it hits the oil surface and the direction of air is reversed due to suction of engine and turns back towards wire mesh filters 42, 44 for a passage through the fine perforations present therein to filter any particulate matter, e.g. dust particles contained in this fresh air A for cleaning thereof. Subsequently, this clean filtered air A+ is supplied to the engine. However, the problem associated with this conventional air filter is that while the air stream strikes the oil surface, a substantial amount of oil particles is also transported by this air into the engine, which is called as oil pull-over. This “oil pull-over” phenomenon causes increased oil residue and contamination on the pistons, intake and exhaust manifolds, fuel injectors and valves, and thus results in increased emissions and reduces the engine’s oil economy. Usually, this oil pull-over is observed to be more than 1% by weight of the oil present in the air-filter’s oil reservoir. Moreover, the high-pressure drop observed in conventional air-filter 50 also leads to choking thereof, thereby reducing the service life of air-filter 50.

Figure 2 shows a front cross-sectional view of an oil bath-type air-filter with controlled oil pull-over configured in accordance with the present invention, for example an oil-bath type air filter of an automobile engine such as tractor engine and operating in contaminated environment, such as an agricultural tractor. The oil filter 150 comprises a housing 110 mounted on an oil reservoir 120. An intake pipe 130 is configured with two open ends 132, 134. The upper end 132 of intake pipe 130 allows the entry of fresh air A into 1 oil-filter housing 110 and is attached on top thereof. The other end 134 of intake pipe 130 is disposed slightly above the oil level in oil reservoir 120. A lateral opening is provided near the upper portion of housing 110 for connecting outlet pipe 140 thereto, to supply clean filtered air A+ to engine automobile E, e.g. agricultural tractor engine. Two primary wire mesh filters 142, 144 are disposed in the middle portion of housing 110, which are mutually separated by a spacer 146, preferably made of rubber. In this configuration, filters 142, 144, 148 divide the housing into three portions 112, 114 and 116 respectively. Further, a final filter chamber 112 is formed between the inner wall of housing 110 and outer surface of dry filter cartridge 148 connected to an outlet pipe 140 supplying filtered clean air to the internal combustion engine, e.g. of agricultural tractor.
However, in contrast to the conventional air-filter 50 of Figure 1, intake pipe 130 is provided with a plurality of circumferential openings or holes 136 to bypass a small amount of fresh air AF (which is however full of dirt or suspended particulate matter) directly charging into the housing 110 to mix with the returning air AR from the other end 134 of intake pipe 130. This continuous mixing of incoming fresh air AF with partially filtered returning air AR reduces the pressure drop of the overall air-filter assembly 150. These circumferentially placed bypass openings 136 necessitate spacer 146 to be shifted to the inner periphery of wire mesh filters 142, 144 to be supported around the peripheries thereof, e.g. spacer 146 is made annular. The secondary dry filter element 148 is disposed above the upper wire mesh filter 142. The intake air A passes through intake pipe 130, exits the lower end 134 thereof and strikes oil surface in oil reservoir 120 and redirected by a bowl 122 to return towards wire mesh filters 142, 144 as returned air flow AR, to pass through filters 142, 144 and to enter dry filter element 148 for final filtration/cleaning thereof and finally filtered clean air AC is collected in annular chamber 112 of housing (110) formed outside dry filter cartridge (148) is supplied to engine E. Accordingly, a small amount of fresh air AF is continuously bypassed via holes 136 into the space of housing 110 surrounding air intake pipe 130 to mix with fresh air AF returning as return air flow AR to significantly reduce the pressure drop within this filter assembly 150.

This reduced pressure drop substantially reduces the usual “oil pull-over” effect (prevalent in conventional oil filter 50 shown in Figure 1) of this cleaner, filtered air to be supplied to the automobile/tractor engine E.

In an exemplary configuration of oil filter 150, three rows of bypass openings or circular holes 138 are provided, each having a plurality of holes of 18 mm diameter each.

WORKING OF THE INVENTION

In accordance with the present invention, the locations/levels, size/s and number/s of above-described bypass openings 136 can be suitably adapted to restrict the potential oil pull-over effect, for example which may be developed in different the different engines of automobiles, e.g. agricultural tractors.

Thus, the oil pull-over effect is successfully maintained within the mandatory/stipulated acceptable limits thereof, e.g. within 0.25% by weight of the oil present in oil reservoir 120 of air-filter 150 discussed above.

Due of addition of holes 136 in the vertical air intake pipe 130, a small amount of air is bypassed directly towards dry filter element 148, which results in a substantial pressure drop, which in turn leads to significant reduction in oil pull-over.

The advantage associated with this improved air-filter 150 is that due to reduced pressure drop, the secondary dry air-filter 148 experiences reduced choking thereof, to substantially increase the service life of this air-filter 150.

A further advantage of the present invention is that the same filtering effect is achieved with a smaller air cleaner 150, due to enhanced performance thereof.

Finally, this air-filter 150 configuration also significantly reduces the overall cost of the air-filter system for automobiles/tractors operating in dusty environment.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The low-cost oil-bath-type air-filter configured with controller pull-over in accordance with the present invention, for example an oil-bath type air-filter of automobile engine, such as tractor engine operating in contaminated environment, which air-filter offers the following advantages:

• Simple and thus low-cost construction.

• Low maintenance and operational cost.

• Significantly reduced “oil pull-over”.

• “Oil pull-over” configurable within stipulated limits for different engines.

• Achieves much better performance with smaller air-filter size.

• Solves the packaging issue related to air-filters in automobiles/tractors.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.

It is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation. The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention.

Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification. Accordingly, the skilled person may make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification, the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to imply including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

The description of the exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top”, and “bottom” as well as derivatives thereof (e.g. “horizontally”, “downwardly”, “upwardly” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion.

These relative terms are for convenience of description and do not require that the corresponding apparatus or device be constructed or operated in a particular orientation.

Terms concerning attachments, coupling and the like, such as “connected” and “interconnected”, refer to a relationship, wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.