WO2017051436A1

WO2017051436A1 - Improved panel air filter element

Info

Publication number: WO2017051436A1
Application number: PCT/IN2016/050319
Authority: WO
Inventors: Sagar Rajendra PATIL; Ajay Kumar MADDINENI; Ganesh Gangadhar GARKHEDKAR; Subhashchandra Mahadeorao CHAKOTE
Original assignee: Varroc Polymers Pvt. Ltd.
Priority date: 2015-09-25
Filing date: 2016-09-23
Publication date: 2017-03-30
Also published as: WO2017051436A4

Abstract

This invention discloses an automotive panel air filter element made in plastic frame and method of making the same; wherein the air filter medium has surface area of more than13.32 square meter/square meter of the area of the air filter frame, fitted in filter frame with pleat pitch less than 4.5 mm. The automotive panel air filter of this invention is for use in 2 Wheelers, 3 wheelers, 4 wheelers or for multi-wheel trailers/containers. The illustrated automotive panel air filter has pleat depth 30mm, pleat pitch 2.5mm, a pleat count of 52 numbers per 24 square meter of the filter medium per square meter of the area of the automotive panel air filter; wherein, compared to prior art, the Dust Holding Capacity increased by 4.73 times, pressure restriction decreased by 2.56%, and efficiency in terms of cleanliness of the air passed through the filter is same.

Description

IM PROV E D PA NE L AIR FIL T E R E L E M E NT

F ield of invention

This invention pertains to air filters used for automobile engines which are associated with automotive panel air filter element. Background of the invention

The panel filters currently in use for automobiles for the purpose of filtering off the dust from the air that is supplied to the engine comprise a filter frame made of plastic by injection molding along with a cellulose filter paper used as an insert in the process of molding. In this process, wherein the pleat depth is usually 10-40 mm, it is the limitation of this design to further increase in the filtration area within same filter frame area that it permits pleat pitch of 4.5 mm only and lesser pitch is not possible. The media porosity used is 83 %. Filter paper medium/material is cellulose and the plastic material used for the frame is polypropylene. The surface area of the filter medium available for dust collection is maximum up to 0.85-2.28sq meter of filter frame area. These types of panel filters are in used since the year1932. The capacity of these panel filters is limited by the maximum Dust Holding Capacity, which is limited by the maximum surface area of the filter medium that is available for dust collection per unit area of the filter frame. After reaching the maximum Dust Holding Capacity, the entire ai r f i Iter is requi red to be replaced with a new one.

Dust Holding Capacity of currently used panel filters is directly influenced by the surface area of the filtration device / filter paper that is packed per square meter area of the filter element. L imitation of this design of injection molded panel filter arises from the constraint in its pitch i.e. the pitch could be a minimum of 4.5mm and cannot be decreased to a lesser dimension; this pitch is defined and limited by the pitch that can be provided in the fins of insert fixed in the mold which is used for molding plastic frame. It is a standard that machining of pitch between fins of plastic mold insert should not go below 4.5mm. Hence there is no scope of increase in pleat count, at the same time in pleat depth if we go above optimum level then it results in increase in viscous resistance and inertial resistance which results in increase in pressure restriction offered by filter media. Further in this process the filter paper pack gets deformed from its ideal shape due to moulding shrinkages. This adversely affects the performance in terms of pressure drop and the Dust Holding Capacity.

Panel filters having pleat pitch below 4.5 mm, of 2.5 mm, has been achieved in filter frames made in polyurethane by inserting a pre-formed filter paper pack having pleat pitch of 2.5 mm in the polyurethane frame during the process of its moulding itself. However the problem with this kind of element is poor bending rigidity; and this is not an appropriate alternative to plastic frame.

Hence, an air filter element with a pleat pitch below 4.5 has remained an unmet requirement for a very long time in automotive application.

Summary of the Invention

This invention discloses an automotive panel air filter element made in plastic frame, wherein surface area of the air filter medium available for dust collection of more than13.32 square meter of the filter medium per square meter of the area of the air filter frame. The invention comprises an automotive panel air filter element of wherein the filter frame is fitted with an air filter medium, also termed as air filtration device, having pleat pitch less than 4.5 mm. The air filter medium, also termed as air filtration device, is made of filter paper or any other medium made from cellulose with its pleats having pitch less than 4.5 mm bonded with plastic to provide filter paper packs of desired dimensions. The automotive panel air filter of this invention is for use in 2 Wheelers, 3 wheelers, 4 wheelers or for multi -wheel trailers/containers.

The invention is illustrated by an automotive panel air filter wherein the pleat depth is at least 30 mm, pleat pitch is at least 2.5mm, a pleat count of at least 52 numbers per 24 square meter of the f i Iter medi um per square meter of the area of the automotive panel air filter. However, depending on the requirements of the automobile, these dimensions can vary.

In one embodiment of this the automotive panel air filter of this invention the Dust Holding Capacity is increased by 4.73 times of Dust Holding Capacity of automotive panel air filter element as compared to prior art model, pressure restriction is decreased by 2.56% as compared to prior art model, and efficiency is same as pri or art model i n terms of cl eanl i ness of the ai r passed through the f i Iter. This invention also comprises a method/process of making automotive panel air filter element comprising a filter frame made in plastic wherein surface area of the air filter medium available for dust collection of more than13.32 square meter of the filter medium per square meter of the area of the air filter frame comprising step of increase in number of pleats of the filter medium per square meter area of the filter frame. In the method of this invention, the air filter element made in plastic is made separate from the air filter medium having a pleat pitch of less than 4.5 mm, the pleats are bonded at corners of the edge of the pleats to each other, preferably by means of plastic, and cut in the form of a filter paper pack for fitting in the filter frame; and thereafter the filter paper pack is bonded to the plastic air f i Iter frame. T he bondi ng of the pi eats to each other and of the f i Iter paper pack to the filter frame with a pleat pitch of less than 4.5 mm is achieved by bonding of pleats by applying a Ί-lot Melt Adhesive_,.

The Hot Melt Adhesive is applied to filter paper medium that is pleated with a pitch of less than 4.5mm, preferably with 2.5mm accompanied with applying hot melt between two adjacent ends of the pleats on upstream and downstream side of the filter pack thereby achieving lesser than 4.5mm pitch and resulting into a filter paper pack that has pleats of the desired pitch lesser than 4.5mm wherein pleating is bonded with Hot Melt Adhesive.

The method/process comprises cutting a filter paper roll by a slitting machine with requi red wi dth for f i I ter, adj usti ng the wi dth of the ai r f i I ter el ement accordi ng to the requirement of the model of the automobile, adjusting the depth of the pleats according to the requirement of the model of the automobile, making the pleating either manually or preferably making pleating by a paper pleating machine comprising the steps of: (a) loading the filter paper on the machine such that the clean surface of the filter paper is facing upwards (Figure 7), (b) passing through an in-line pre-drying oven [(8) and (9)] through which the loaded paper passes with temperature and residence time of the paper adjusted for the purpose of removing moisture content in paper (3), (c) creasing the paper to pre-determine the location on which it shall fold at a later step, thereafter processing for gluing the paper pleating by application of Hot Melt Adhesive on selected portions; preferably as two bands at least on the corner margins of the filter paper [(5) and (6)], either manually or by machine wherein the Hot Melt Adhesive is applied through nozzles (12)which have connection with HOT-melt Adhesive tank(13), this tank(13) is filled with HOT-melt Adhesive, the tank is maintained at temperature of 120°C and nozzle temperature is 140°C, the Hot Melt Adhesive (5) & Hot Melt Adhesive (6) dispensing nozzles dispensing Hot Melt Adhesive continuously starting from the edge of the paper up to a certain distance inwards from both the ends of the filter paper margins, folding the filter paper either (i) manually, or (ii) with the help of machine that has creasing rollers [( 10)( 11)] and mechanism of gears [(14) (15)]; wherein the creasing rollers have a special pattern machined on its surface called as ^'crease_,, this horizontal crease being the location on which the filter paper gets indented for eventual formation of a pleat on that location later on, and the mechanism of gears [(14) (15)] is such that pleats are formed resulting into coming of the surface of the pleats adjacent to each other and on the edges of which HOT-melt Adhesive is applied, leading to sticking of the edges of both surfaces of adjacent pleats together, finally leading to formation of a single long continuous pack of pleated filter paper, cutting the single block lengthwise to get individual paper packs of desired size to make the filter paper packs.

DE TAIL E D DE SC RIPTION OF T H E INV E NT ION

Brief description of figures and legends F igure 1.1 : General features/structure/design/parts of an air filter element of this invention

Upstream view. Body of filter frame (1), HOT-melt Adhesive at upstream of filter (2) and the pleated filter paper (3).

Figure 1.2: Section view of figure 1.1 through line A-A and viewed from side; showing the HOT-melt Adhesive(2) & (4). Figure 1.3 Section view of figure 1.1 through line B-B and viewed from side showing the HOT-melt Adhesive (5) & (6).

F igure 2: Detailed Diagrammatic view of figure 1.2,a vertical Section taken along the I i ne A - A of F i gure 1.1 of the f i I ter el ement of thi s i nventi on showi ng body of filter frame (1), HOT-melt Adhesive at upstream of filter (2), filter paper (3)

&HOT-melt Adhesive at downstream of filter (4).

F igure 2.1 : Shows magnified view of the top end of the Figure 2.

F igure 3: Section B-B of filter element

Detailed diagrammatic magnified view of figure 1.3showing filter paper (3),

HOT-melt Adhesive (5) at one side and HOT-melt Adhesive (6) on other side of filter paper pack, HOT-melt Adhesive at upstream of filter (2), filter paper (3)

&HOT-melt Adhesive (4) at downstream of filter.

F igure 3.1 : V iew B

This is a magnified view of section B-B at one of its sides labeled as (1) showing HOT-melt Adhesive (5), upstream HOT-melt A dhesive( 2) and downstream HOT- melt Adhesive (4). F igure 4: Pleated paper pack wherein the surface joined with HOT-melt Adhesive at downstream is placed as down surface and is not visible. The figure also shows HOT-melt Adhesive (5) and (6) applied on the sides.

F igure 4.1 : U pstream vi ew of paper pack with H OT-melt A dhesive at a stage j ust before applying HOT-melt Adhesive on the upstream:

Filter paper pack made from Filter paper (3) by applying HOT-melt Adhesive on the downstream si de (not visi ble i n the figure si nee it is on the down surface of the figure) is further sealed on the sides with HOT-melt Adhesive(5) and HOT-melt Adhesive (6) as shown in Figure 4.2.

F igure 4.2: Downstream view of paper pack with H OT -melt Adhesive Filter paper (3) pack after sealing with HOT-melt Adhesive (5) & (6).

Figure 4.3 Side view of paper pack showing HOT-melt Adhesive (5) sealed with filter paper (3)

F igure 5: Paper pack assembly in plastic frame from downstream view Downstream of filter paper pack shown in Figures 4 and 4.2 as it is fixed into filter frame, filter paper (3) had been cut along its width for desired width. In the illustrated case, the same is 95mm.

F igure 6: Downstream side gluing of paper pack and frame by H OT-melt Adhesive

Shows dispensing of HOT-melt Adhesive (4) on paper pack to its downstream side of paper pack shown in figure 4 over the HOT-melt Adhesive (5) and HOT- melt Adhesive (6) and closing the gap between the edge of the HOT-melt Adhesive (5) and the edge of the frame (1) and between the edge of the HOT-melt Adhesive (6) and the edge of the frame (1) as shown in figure- 6(so that after application of the HOT-melt Adhesive (4) the HOT-melt Adhesive (5) and HOT- melt Adhesive (6) are fully covered and not visible) to prevent leak from the filter element.

F igure 6.1 : Upstream side gluing of paper pack and frame by H OT -melt Adhesive

HOT-melt Adhesive (2) dispensing on paper pack to its upstream side shown in figure 4.1, and frame (1) as shown in figure- 6. Purpose of this gluing is to support paper pack shown in figure 4 so that it should not fall while handling.

F igure 7: F ilter paper pleating process & pleating mechanism

Detailed view of pleating process and pleating mechanism is shown in figure 7. The purpose of this invention was to provide solution to the long standing need to improve the life of the panel air filter in automobiles as much as possible.

Objective of this invention was to provide high Dust Holding Capacity and good efficiency without increase in pressure restriction in limited packing area available for the filter element or without increasing the size of the filter element. The size of the filter element depends on the design of the housing of the filter element. Design parameters such as pleat depth and number of pleats are standardized in such a way that we can get less pressure restriction. This standard could not be reached to its optimum level in the prior art method of making air filter with limitation of pitch of 4.5 mm in an injection moulding process of plastic frames; and with above described drawback of less rigidity of polyurethane frames Thus, there was a necessity to improve the filter design to get higher dust holding capacity.

For the purpose of this specification, some parameters related to performance of the Air Filter have the meaning as defined below, or method of determining the parameters are as defi ned / descri bed bel ow

Pressure Restriction:

^'Pressure Restriction_, measures how difficult it is for the air to get through the filter and is measured in inches of aquaA/vater (H₂0). Instead of referring to restriction, the industry uses "air flow" to describe the effect of restriction. Lower the restri cti on of a fi I ter the better will be the ai r f I ow.

F ilter E fficiency:

Efficiency is measured in % and is the amount of dirt/contaminants that the filter stops from goi ng i nto the engi ne.

Dust holding Capacity:

Dust Holding Capacity is the total amount of contaminants/dirt the filter will hold before reaching its termination point. The termination point is a predefined restriction point that is used as the cut-off point when measuring how much dirt a filter will hold. For lower capacity vehicles, 100-150mm of aqua is used at the termination point. At this termination point for lower capacity vehicles, usually about 20 gram dust gets collected. For heavy duty trucks, this number is greater than 250mm of aqua. At this termination point for higher capacity vehicles, usually about 300 gram dust gets collected. Test dust used for this test is: SA E J 726 Fine, SA E J 726 fine dust contains 5.5um of dust particle having maximum volume fraction of 41 %-35%, similarly for 11 micron it is 57%-51 %, for 22micron it is74%-68%, for 44 micron it is 92%-86% & for 176 micron it is 100% .

This invention comprises a panel air filter of an automobile comprising a filter frame made in plastic fitted with an air filter medium having pleat pitch less than 4.5 mm for f i Iteri ng off dust from the ai r enteri ng i n the engi ne of the automobi I e. The panel air filters of the instant invention may be used for 2 Wheelers, 3 wheelers, 4 wheelers or for multi-wheel trailers/containers.

This instant invention comprises improvement achieved by increase in number of pi eats of the f i Iter medi um per square meter area of the f i Iter frame.

Filtration area is dependent on pleat width, pleat depth and pleat count. Because width of the filter frame is not amenable to any change, the packing area of the pleats was limited. To increase number of pleats there is necessity to decrease in pleat pitch. Decrease in pleat pitch was not possible in the process of insert molding (the terms ^'molding_, and ^'moulding_, are used interchangeably to indicate same process of casting the part in a mold/mould) of plastic frames as well as polyurethane inn their respective injection moulding processes; hence the same was replaced by an alternative process wherein mechanism other than insert molding during injection moulding process has been used for incorporating the f i Iter el ement i n the f i Iter frame.

According to the alternative process, plastic frame is produced independently by injection moulding process and the filter paper pack with pleat pitch of less than 4.5 mm is produced separately and thereafter both are bonded to each other. This step is not technically possible with polyurethane frame, and further the polyurethane frame shall have less rigidity. Thus, the increase in pleat counts gives major increase in filtration area.

The air filter medium may comprise a sheet of a material that has pores of a size capable of stopping dust particles to go through to the other side of the media. A conveniently available material for such a sheet comprises cellulose and it is used in current context.

In one embodiment of achieving surface area of the air filter medium available for dust collection of more than13.32 square meter of the filter medium per square meter of the area of the air filter frame this invention, the air filter element comprises a laminated unit (a plastic bonded unit) having a cellulose filter media as air filtration device, wherein the downstream side (side from which air gets out of the Panel Filter) of the filter element comprises pleat pitch of less than 4.5 mm. In one embodiment of this invention, pleat pitch of smaller than 4.5 mm is achieved by bonding of pleats by HOT-melt Adhesive. A ΊΗΟΤ-melt Adhesive_, is a composition which melts while hot as glue and solidifies by cooling within a short time to achieve sticking of two surfaces on which this HOT-melt Adhesive is applied. HOT-melt Adhesives, also known as ^'hot glue_ is a form of thermoplastic adhesive. The HOT-melt Adhesive used in the illustration in the instant invention is ethyl ene-vinyl acetateco-polymer based hot-melt adhesive, This HOT-melt Adhesive contains 60 %- 70% of ethylene-V inyl Acetate Polymer& 30%-40% hydrocarbon resin. Hot melt of any other composition may be used if it can melt whi I e hot at easi ly workabl e temperature and sol i dif i ed when cooled at room temperature.

Hot-melt A dhesives usually have following properties: a) Melt viscosity: one of the most noticeable properties influences the spread of applied adhesive, and the wetting of the surfaces. Temperature-dependent, higher temperature lowers viscosity, b) Melt flow index: a value roughly inversely proportional to the molecular weight of the base polymer. High melt flow index adhesives are easy to apply but have poor mechanical properties due to shorter polymer chains. Low melt flow index adhesives have better properties but are more difficult to apply, c) Pot life stability: the degree of stability in molten state, the tendency to decompose and char. Important for industrial processing where the adhesive is molten for prolonged periods before deposition, d) Bond-formation temperature: mi ni mum temperature bel ow whi ch suff i ci ent wetti ng of substrates do not occur. In one embodiment of this invention, the filter paper medium is pleated with a pitch of less than 4.5 mm, preferably with 2.5 mm accompanied with applying hot melt between two adjacent ends of the pleats. This helps in achieving lesser than 4.5 mm pitch. This action results into a filter paper pack that has pleats of the desired pitch. This pack of filter paper which results from pleating is bonded with HC M (Hot melt adhesive) on upstream and downstream side of the filter pack. Smaller pitch may also be chosen which results in higher filtration area per square meter of the area of the filter frame for achieving higher DHC (Dust Holding capacity) & higher filtration efficiency. In one embodiment, the process of obtaining pitch of 2.5 mm, further comprises steps of cutting a filter paper roll by a slitting machine with required width for filter and then it is processed for paper pleating and HOT-melt Adhesive(5) &HOT-melt Adhesive (6) gluing as described above. The width preferred in the instant illustration is 95mm, which is considered as convenient for the panel filters of2 wheeler automobiles. This width can be adjusted according to the requirement of the automobiles. The depth of the pleat preferred for the instant illustration is 30 mm; which can also vary according to the requirements of the model as well as type of the automobile (either 2 wheeler or more wheeler). The pleating can be made manually; however, it is more conveniently done by using a Paper Pleating Machine.

A Paper Pleating Machine suitable for this purpose comprises: (a) paper loading on machine such that the clean surface of the filter paper is facing upwards( Figure 7), (b) an in-line pre-drying oven (8) and (9) through which the loaded paper passes with temperature and residence time of the paper adjusted for the purpose of removing moisture content in paper (3), (c) creasing the paper to pre-determine the location on which it shall fold at a later step, (d) applying HOT-melt Adhesive thereafter on selected portions as two bands at least on the corner margins of the filter paper (5) and (6), (d) folding the filter paper with the help of mechanism of gears (14) (15) such that pleats are formed resulting into coming of the surface of the pleats adjacent to each other and on the edges of which HOT-melt Adhesive is applied, leading to sticking of the edges of both surfaces of adjacent pleats together, finally leading to formation of a single long continuous pack of pleated filter paper, (e) cutting the single block lengthwise to get individual paper packs of desired size. The HOT -melt Adhesive may be applied at any other location as long as it serves same purpose as applying the HOT-melt Adhesive on the edges i.e. of resulting into sticking of the edges of both surfaces of adjacent pleats together, finally leading to formation of a single long continuous pack of pleated filter paper.

HOT-melt Adhesive is applied through nozzles (12) which have connection with HOT-melt Adhesive tank (13), this tank (13) is filled with HOT-melt Adhesive, the tank is maintained at temperature of 120°C and nozzle temperature is 140°C. In the machine used for this illustration, the mechanical means used for pleating are creasing rollers (10)(11)which have a special pattern machined on its surface called as ^'crease_,, this horizontal crease is the location on which the filter paper gets indented for eventual formation of a pleat on that location later on. The HOT- melt Adhesive (5) &HOT-melt Adhesive (6) dispensing nozzles dispense HOT- melt Adhesive continuously starting from the edge of the paper up to a certain distance inwards from both the ends of the filter paper margins. In the illustration, this distance is 4 mm. Final product of this process is shown in figure 4, figure 4.1 & figure 4.2. Paper pack shown in figure 4 is ready to get fixed into plastic frame (1).The Figure 5 shows this paper pack of figure 4 after placing in plastic frame and just before the same is finally fixed with the plastic frame 1 using the hot melt. HOT-melt Adhesive (4) is then dispensed from top and the final product of this process, as seen from downstream side, is shown in figure 6. HOT -melt Adhesive temperature is 120°C. Width of HOT -melt Adhesive (4) is 7 mm from both ends of pleating curves towards the center of the longer sides of the filter frame & 2 mm from both top & bottom ends of the filter frame towards the center of the shorter sides of the filter frame as shown in figure 6. It takes 2 minutes for curing of the HOT-melt Adhesive. Configuration of HOT-melt Adhesive (2) width to its upstream side is different from downstream side HOT- melt Adhesive (4). HOT-melt Adhesive (2) width is 2mm for all four sides as shown in figure 6.1. After 2 minutes of curing final product becomes ready.

Permeability of this filter media is 491 l/M²sec (liter of air per square meter per second); it is also chosen according to standard which will give good efficiency. This value is already optimized according to the viscous resistance of this media due to this it will not affect much on pressure restriction due to inertial impaction. This design having pleat depth of 30mm, pleat pitch of 2.5mm has a pleat count is 52 numbers per24 square meter of the filter medium per square meter of the area of the air filter frame this invention. This gives increase in DHC by 4.73 timesof dust holding capacity of old / currently used filter, pressure restriction decreased by 2.56% and efficiency is same as prior art model in terms of cleanliness of the air passed through the filter.

Performance evaluation by testing:

This filter element was tested as per ISO 5011 in air filter test rig, which tests pressure restriction, dust holding capacity and efficiency of filter. The test sequence begins with measuring the pressure drop of a clean filter as a function of the airflow rate which is measured in cubic feet per minute (CFM). Subsequently, the cumulative efficiency and dust loading capacity are measured.

Claims

C laims :

An automotive panel air filter element made in plastic air filter frame wherein surface area of the air filter medium available for dust collection of more than13.32 square meter of the filter medium per square meter of the area of the ai r f i Iter frame.

The automotive panel air filter element of claim 1 wherein the filter frame is fitted with an air filter medium, also termed as air filtration device, having pleat pitch less than 4.5 mm

The automotive panel air filter of claim 2 wherein the air filter medium, also termed as air filtration device, is made of filter paper or any other medium made from cellulose with its pleats having pitch less than 4.5 mm bonded with plastic to provide filter paper packs of desired dimensions.

The automotive panel air filter of claim 1for use in 2 Wheelers, 3 wheelers, 4 wheelers or for multi-wheel trailers/containers.

The automotive panel air filter of claim 1 wherein the pleat depth is at least 30mm, pleat pitch is at least 2.5mm, a pleat count of at least 52 numbers per 24 square meter of the filter medium per square meter of the area of the automotive panel ai r f i Iter.

T he automotive panel air filter of claim 1 wherein:

a. the Dust Holding Capacity is increased by 4.73 times of Dust Holding Capacity of automotive panel air filter element as compared to prior art model, the ust Holding Capacity_, being the total amount of contaminants/dirt the filter will hold before reaching its termination point,

b. pressure restriction is decreased by 2.56% as compared to prior art model, ^'pressure restriction_, being a measure of how difficult it is for the air to get through the filter and is measured in inches of aqua/water (H₂0), and

c. eff i ci ency i n terms of cl eanl i ness of the ai r passed through the f i Iter is same as prior art model.

A method/process of making automotive panel air filter element comprising a filter frame made in plastic wherein surface area of the air filter medium available for dust collection of more than13.32 square meter of the filter medium per square meter of the area of the air filter frame comprising step of increase in number of pleats of the filter medium per square meter area of the f i Iter frame

The method/process of making automotive panel air filter element of claim 7 wherein the air filter element made in plastic is made separate from the air filter medium having a pleat pitch of less than 4.5 mm, the pleats bonded at corners of the edge of the pleats to each other, preferably by means of plastic, and cut in the form of a filter paper pack for fitting in the filter frame; and thereafter the filter paper pack is bonded to the plastic air filter frame

The method/process of claim 8 wherein the bonding of the pleats to each other and of the filter paper pack to the filter frame is achieved by bonding of pleats by applying a Ί-lot Melt Adhesive_,; the Ί-lot Melt Adhesive_, being a composition which melts while hot as glue and solidifies by cooling within a short time to achieve sticking of two surfaces on which this Hot Melt Adhesive is applied.

10. The method/process of making automotive panel air filter element of claim 9 wherein:

a. the Hot Melt Adhesive, also known as ^'hot glue_, comprises a form of thermoplastic adhesive, further comprising ethyl ene-vinyl acetateco- polymer based hot melt adhesive that contains 60 %- 70% of ethyl ene-V inyl Acetate Polymer & 30%-40% hydrocarbon resin or any other hot melt of any other composition that can melt while hot at easily workable temperature and solidified when cooled at room temperature,

b. the Hot Melt Adhesive is applied to filter paper medium that is pleated with a pitch of less than 4.5mm, preferably with 2.5mm accompanied with applying hot melt between two adjacent ends of the pleats on upstream and downstream side of the filter pack thereby achieving lesser than 4.5mm pitch and resulting into a filter paper pack that has pleats of the desired pitch lesser than 4.5mm wherein pleating is bonded with Hot Melt Adhesive.

11. T he method/process of maki ng automotive panel ai r f i Iter el ement of cl ai m 9 with filter paper packs having a pitch of lesser than 4.5mm comprising following steps: a. cutting a filter paper roll by a slitting machine with required width for filter,

b. adjusting the width of the air filter element according to the requirement of the model of the automobile,

c. adj usti ng the depth of the pi eats accordi ng to the requi rement of the model of the automobile,

d. maki ng the pi eati ng, either manual ly or preferably maki ng pi eati ng by a paper pleating machine comprising the steps of: (a) loading the filter paper on the machine such that the clean surface of the filter paper is facing upwards (Figure 7), (b) passing through an inline pre-drying oven [(8) and (9)] through which the loaded paper passes with temperature and residence time of the paper adjusted for the purpose of removing moisture content in paper (3), (c) creasing the paper to pre-determine the location on which it shall fold at a later step,

e. thereafter processi ng for gl ui ng the paper pi eati ng by appl i eati on of Hot Melt Adhesive on selected portions; preferably as two bands at least on the corner margins of the filter paper [(5) and (6)], either manually or by machine wherein the Hot Melt Adhesive is applied through nozzles (12)which have connection with HOT-melt Adhesive tank(13), this tank(13) is filled with HOT-melt Adhesive, the tank is maintained at temperature of 120°C and nozzle temperature is 140°C, the Hot Melt Adhesive (5) & Hot Melt Adhesive (6) dispensing nozzles dispensing Hot Melt Adhesive continuously starting from the edge of the paper up to a certain distance inwards from both the ends of the filter paper margins, folding the filter paper:

i. either manually, or

i i . with the hel p of machi ne that has creasi ng rol I ers [( 10)( 11 )] and mechanism of gears [(14) (15)]; wherein the creasing rollers have a special pattern machined on its surface called as ^'crease_,, this horizontal crease being the location on which the filter paper gets indented for eventual formation of a pleat on that location later on, and the mechanism of gears [(14) (15)] is such that pleats are formed resulting into coming of the surface of the pleats adjacent to each other and on the edges of which HOT-melt Adhesive is applied, leading to sticking of the edges of both surfaces of adjacent pleats together, finally leading to formation of a single long continuous pack of pleated filter paper, cutting the single block lengthwise to get individual paper packs of desi red size to make the f i Iter paper packs.