GB2286136A

GB2286136A - Air filter

Info

Publication number: GB2286136A
Application number: GB9500599A
Authority: GB
Inventors: Christopher Cosby; Stephen Jonathan Hodder
Original assignee: AC DELCO SYSTEMS OVERSEAS CORP
Current assignee: AC DELCO SYSTEMS OVERSEAS CORP
Priority date: 1994-02-02
Filing date: 1995-01-12
Publication date: 1995-08-09
Anticipated expiration: 2015-01-12
Also published as: GB9500599D0; GB2286136B

Abstract

An air filter (10) for filtering air passing into the passenger compartment of an automotive vehicle includes a filter sheet (12) of pleated filter material including first and second sides formed by the ends of the pleats of the filter sheet, and first and second side strips (14) each bonded to a respective side of the filter sheet (12). The side strips (14) are formed of substantially the same material as the filter sheet (12) and may be moulded, welded, or adhered to the filter sheet (12). The side strips (14) have substantially the same thickness as the thickness of the filter medium forming the pleated filter sheet (12). The material and its thickness are such as to provide a substantially rigid, self-supporting, air filter (10) which makes the filter (10) readily recyclable. <IMAGE>

Description

AIR FILTER The present invention relates to an air filter for filtering air passing to a passenger compartment of a vehicle and to apparatus for producing such a filter.

Air filters are commonly provided for filtering air fed into the passenger compartment of a vehicle by a ventilation unit, so as to remove pollutants. Such filters are generally formed of a sheet of suitable filter medium, of type well known in the art, which is pleated. In order to give the sheet of filter medium adequate mechanical strength, the filter generally includes some form of frame having a shape corresponding to the shape of the perimeter of the filter sheet and which is adhered or otherwise secured thereto. In another example, the ends of the pleats are folded over one another at each side of the filter.

Where the filter is supported in a frame, additional cost is incurred as a result of the separate frame and in the additional processing steps required to fit and secure the filter to the frame.

Where the ends of the pleats are folded over one another, it is necessary to provide a significant amount of additional filter medium, which is relatively expensive, and complicates the manufacturing process.

The present invention seeks to provide an improved air filter and apparatus for and method of producing such a filter.

According to an aspect of the present invention, there is provided an air filter comprising a filter sheet of pleated filter material including first and second sides formed by the ends of the pleats of the filter sheet, one or more side strips bonded to the first side, and one or more side strips bonded to the second side of the filter sheet, wherein each side strip is formed of substantially the same material as the filter sheet, the filter material having a predetermined composition and a predetermined thickness such that the air filter is substantially rigid.

The present invention provides a selfsupporting structure which does not require a separate supporting frame and does not waste filter material.

Further, manufacture of the air filter is easy and cheap. Additionally, the use of the same material for the filter sheet and the side strip or strips can make the filter readily recyclable, avoiding any need first to disassemble parts of the filter as may be necessary with air filters formed of a plurality of different materials or having a separate supporting frame.

In an embodiment, each side strip is moulded to the filter sheet. Alternatively, each side strip may be adhered to the filter sheet. As a further alternative, each side strip may be bonded by ultrasonic welding.

Advantageously, the ends of the pleats are folded so as to lie substantially perpendicularly to the longitudinal direction of the pleats, the side strips being bonded to the folded ends of the pleats.

This can further increase the strength of the air filter and facilitate bonding of the side strip or strips to the pleated filter sheet.

Preferably, a single side strip is bonded to each side, the side strips being substantially of the same thickness as the thickness of the filter medium forming the pleated filter sheet.

According to another aspect of the present invention, there is provided apparatus for producing an air filter as herein defined comprising a filter medium dispenser for dispensing filter medium in sheet form, a pleating system for pleating the filter medium, a side strip applicator for applying one or more side strips of the same filter material as the pleated filter sheet onto each side of the pleated filter sheet, and a cutting station for cutting the filter sheet into individual air filters.

An embodiment of the present invention is described below, by way of illustration only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an embodiment of air filter in partially assembled form; and Figure 2 is a side elevational view in schematic form of an embodiment of apparatus for assembling an air filter.

Referring to Figure 1, the embodiment of air filter shown in partially assembled form is intended for location in the air intake passage of a ventilation system of a vehicle passenger compartment.

The air filter removes pollutants from the atmospheric air fed through the ventilation system, such as emissions from other vehicles and pollen.

The air filter 10 has a generally rectangular shape in this embodiment and is formed of three parts, a pleated filter sheet 12 and first and second side strips 14. The filter sheet 12 is formed from any suitable woven or non-woven filter medium which will provide the required self-supporting nature for the air filter 10. An example is a non-woven needled felt, such as a blend of polypropylene and modacrylic fibres (preferably in a 50:50 blend). The filter medium must also have a thickness which will provide the required self-supporting nature. In the case of the above example, a thickness of 1.6 mm is preferred, although a thickness as low as 1.0 mm may be adequate. Preferably, the filter medium is electrostatically charged.

The filter material is folded into pleats and compressed in concertina manner by a method described in further detail below. The pleated or concertinaed filter material defines side edges which lie in a plane substantially perpendicular to the longitudinal direction of the pleats.

The two side strips 14 have a width substantially the same as the depth of each pleat of the filter sheet 12 such that when the air filter is assembled, the edges of the side strips 14 are substantially aligned with the upper and lower surfaces of the pleated filter sheet 12. The two side strips 14 are made of substantially the same material as the filter sheet 12 and preferably of exactly the same material. The side strips 14 are secured to the sides of the filter sheet 12 by welding or suitable adhesive placed between the internal surfaces 16 of the side strips 14 and the side edges of the pleated filter sheet 12.

The side strips 14 preferably are of the same thickness as the thickness of the filter medium forming the pleated filter sheet 12.

In use, the air filter 10 is simply positioned in housing (not shown) in a vehicle. The air filter 10 is usually subjected to a small compressive force whilst retained in the housing to press the air filter against a sealing strip of, for example, elastomeric or foam rubber material positioned in the housing. When replacement is required, the old air filter is removed from the housing, leaving the sealing trip behind, and replaced by a new filter. The old filter is then easily recycled as it is substantially totally formed from a single type of material.

Referring to Figure 2, the embodiment of filter assembly apparatus 20 shown includes a filter medium dispensing station 22 which supports a roll 24 of filter medium. A pleating station 26 includes a set of rollers 28 which typically apply a number of indentations in the filter medium for use in marking the longitudinal edges of the individual pleats and for ensuring correct spacing of the pleats from one another. An accumulator 30, of known form, accumulates filter medium for subsequent pleating by the pleating system 32.

The pleating system 32 is of conventional form and may, for example, include a system of toothed belts which engage one another to fold filter medium located therebetween.

A conveyor 34 passes the pleated filter medium, which at this stage is still in continuous form, to a side strip applicator 36. The side strip applicator 36 preferably includes two filter strip dispensers (not shown) which feed the side strips 14 from rolls of filter material, and biasing means (not shown) for applying pressure against the side strips 14 towards the sides of the pleated filter sheet 12, in the direction of arrows A shown in Figure 1.

In the case where the side strips 14 are moulded to the pleated filter sheet 12, the applicator 36 also includes heaters (not shown) for heating both the side strips 14 and the pleated filter sheet 12.

Such heating causes a softening of the filter material and thereby bonding of the side strips 14 to the pleated filter sheet 12. Any suitable arrangement of heaters may be used.

In the case where the side strips 14 are adhered to the pleated filter sheet 12, two adhesive applicators (not shown) may provided. These applicators may be located proximate respective sides of the filter sheet 12 so as to dispense adhesive to the sides of the filter sheet 12 and/or to the side strips 14. Alternatively, the adhesive applicators may be located adjacent the side strip dispensers so as to apply adhesive solely to the internal surfaces 16 of the side strips 14. Any suitable arrangement of adhesive applicators may be used.

In the case where the side strips 14 are welded to the pleated filter sheet 12, the applicator 36 also includes ultrasonic welders and pressure means (not shown) for welding the side strips 14 under pressure to the pleated filter sheet 12. Such welding causes a softening of the filter material and thereby bonding of the side strips 14 to the pleated filter sheet 12. Any suitable arrangement of welders and the pressure means may be used.

Following application of the side strips 14 to the pleated filter sheet 12, the filter 10 is passed to a cutting station 38 which cuts the continuous filter sheet into individual air filters of appropriate length. Once cut, each air filter is self-supported by the combination of the pleats and the side strips.

The specific design of the stations 22 to 38 shown in Figure 2 will be apparent to the skilled person, so will not be described herein in detail.

Where additional strength is required along the sides of the filter 10, the ends of the pleats may be folded over so as to lie substantially perpendicular to the longitudinal direction of the pleats. In this case, the side strips 14 are welded or adhered to the folded ends of the pleats. It is envisaged that the length of the folded over portions of the pleats will be less than the spacing between the pleats.

At the end of the useful life of the filter 10, the entire filter can be recycled in the same process as a result of the use of the same material for the filter sheet 12 and the side strips 14.

In an alternative embodiment, the side strips 14 may be applied to the pleated filter sheet 12 in a subsequent process, after the filter sheet has been cut into individual filter elements.

In some embodiments, a single side strip may be provided, extending around the perimeter of the pleated filter sheet.

Claims

Claims:

1. An air filter comprising a filter sheet of pleated filter material including first and second sides formed by the ends of the pleats of the filter sheet, one or more side strips bonded to the first side, and one or more side strips bonded to the second side of the filter sheet, wherein each side strip is formed of substantially the same material as the filter sheet, the filter material having a predetermined composition and a predetermined thickness such that the air filter is substantially rigid.

2. An air filter according to claim 1, wherein each side strip is moulded to the filter sheet.

3. An air filter according to claim 1, wherein each side strip is adhered to the filter sheet.

4. An air filter according to claim 1, wherein each side strip is ultrasonically welded to the filter sheet.

5. An air filter according to any one of claims 1 to 4, wherein the ends of the pleats are folded so as to lie substantially perpendicularly to the longitudinal direction of the pleats, the or each side strip being bonded to the folded ends of the pleats.

6. An air filter according to any one of claims 1 to 5, wherein the or each side strip has substantially the same thickness as the thickness of the filter medium forming the pleated filter sheet.

7. Apparatus for producing an air filter according to any preceding claim, comprising a filter medium dispenser for dispensing filter medium in sheet form, a pleating system for pleating the filter medium, a side strip applicator for applying one or more side strips of the same filter material as the pleated filter sheet onto each side of the pleated filter sheet, and a cutting station for cutting the filter sheet into individual air filters.

8. Apparatus according to claim 7, wherein the side strip applicator comprises heating means for heating the filter sheet and side strips so as to mould the side strips to the sides of the filter sheet.

9. Apparatus according to claim 7, wherein the side strip applicator comprises bonding means for applying adhesive to the filter sheet and/or the side strips so as to bond the side strips to the sides of the filter sheet.

10. Apparatus according to claim 7, wherein the side strip applicator comprises ultrasonic welding means for welding the side strips to the sides of the filter sheet.

11. Apparatus according to any one of claims 7 to 10, comprising folding means for folding the ends of the pleats so as to lie substantially perpendicularly to the longitudinal direction of the pleats, the side strip applicator being operative to bond the side strips to the folded ends of the pleats.

12. Apparatus according to any one of claims 7 to 11, comprising a filter sheet marking station for applying indentations in the filter sheet.

13. An air filter substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. Apparatus for producing an air filter substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.