US3133847A - Fluid filters - Google Patents

Description

May 19, 1964 H. E. MILLINGTON FLUID FILTERS 4 Sheets-Sheet 1 Filed Dec. 2, 1960 I/VVEN OR May 19, 1964 H. E. MILLINGTON FLUID FILTERS 4 Sheets-Sheet 2 Filed Dec. 2, 1960 May 19, 1964 H. E. MILLINGTON FLUID FILTERS 4 Sheets-Sheet 5 Filed Dec. 2, 1960 United States Patent Ofi ice 3,133,847 Patented May 19, 1964 3,133,847 FLUID FILTERS Henry Ernest Millington, Crabtree, Plymouth, Devon, England, assignor to Tecalemit Limited, Plymouth, Devon, England Filed Dec. 2, 1969, Ser. No. 73,233 8 Claims. (Cl. 156-69) This invention relates to the construction of filter elements for the filtering of fluids and it is more particularly concerned with the construction of elements of the type in which the element consists of one (or more) sheets of paper or other filter material which is or are pleated or coiled and formed into an annular or other requ red shape and one or more of the edges of which is or are sealed so as to control the passage of the fluid and to ensure that it passes through the filter material. Such filters include those of the star type, in which a sheet of filter material is pleated and is secured in the form of an annular star between a pair of end caps to form the filter element, and those of the spiral type, in which a sheet of filter material is formed with a closed spiral which is secured between end caps to form the element.

Another form of filter to which the invention is applicable is one in which a strip of filter material is pleated along transverse fold lines and is then folded in a fanlike manner to form a fan-type annular element of a more or less disc-like form, in which the pleats radiate from the centre. In the case of this latter element, such as is described in the specification of United States Patent No. 3,076,555, the edges of the filter material are secured to an inner tube and also to an outer sealing band, which parts may be made of paper or other suitable material, to retain the shape of the element and to control the passage of the fluid through the filter material, from one side of the filter element to the other. According to one arrangement, which is described in the last said specification, the outer sealing band may be formed of an elastic material, such as natural or synthetic rubber, which is fitted round and which presses against the edges of the pleated filter material.

When constructing filter elements of the star or spiral type, the usual method, which has been employed to secure the edges of the filter material to the end caps, has been to use an adhesive or cement which is applied to the inner faces of the end caps and into which the edges of the filter material are pressed before the adhesive or cement is caused or allowed finally to harden. Other methods of attaching the end caps involve the use of separate discs of an adhesive which are fitted in the end caps and which are caused to soften when the end caps are pressed against the edges of the filter material.

Such known or previously devised methods of sealing the edges of filter material in fluid filter elements suffer from various limitations or drawbacks, and it has been found the present invention provides an improved method for sealing such edges of filter elements relatively less expensively and in fast mass production with less separate manual operations, thus overcoming the drawbacks of previously proposed methods.

According to the invention, in its broadest aspect, a method is provided for forming a seal between adjacent edges of filter material in the construction of a fluid filter element, which comprises discharging, under pressure an adhesive substance in the form of a liquid onto the said edges, while maintaining relative movement between the point of adhesive-discharge and said edges of the filter element, thereby producing between the adjacent edges a seal which incorporates the adhesive when the latter has hardened.

According to one method of carrying out the invention, an adhesive is sprayed onto the edges of the filter material in such a way, while rotating said edges of the filter, and the adhesive being of such consistency, that it forms a continuous film, when it sets, which connects or bridges the spaces between the adjacent edges of the filter element and prevents fluid when being filtered by the filter element, from passing between the latter edges, thereby ensuring that the fluid passes through the filter material. The adhesive, due to its stiffness when set, also fulfils the important function of maintaining the correct spacing between the pleats or turns of the filter material.

According to an alternative method, the adhesive is applied to the edges of the pleated or spiral filter material by spraying, after which a sealing member is pressed against the said edges and secured to the latter by the action of the adhesive. The sealing member may be an end cap, in the case of filter elements of the star or spiral type, or it may form the inner tube or the outer sealing band, in the case of filter elements of the fan type, such as are referred to above.

According to a modification of this latter method, the adhesive may be sprayed simultaneously onto both the edges of the filter material and onto the surface of the end cap or other sealing member, before the latter is pressed against the filter material.

The particular method and means used, by which the adhesive is sprayed onto the edges of the pleated material, including the angle of the spray and the size and shape of the spray nozzles, are important to the production of the best results.

The present invention is also concerned with the provision of novel or improved filter elements.

According, therefore, to a further feature of this invention, a fluid filter element is provided comprising at least one sheet of filter material which is formed into an annular shape and which includes sealing members which are bonded to adjacent edges of the filter material to ensure that the fluid being filtered passes through the said material, wherein one at least of the sealing members comprises a continuous layer of an adhesive substance which has been sprayed onto the edges of the filter material to form a continuous film sealing the spaces be tween the said edges.

The sealing members may take the place of conventional end caps, in the case of filter elements of the star or spiral type, or of the inner tube and/or outer band, in the case of fan-type elements.

Further features of the present invention will become apparent from the following description.

Reference will be made to the accompanying drawings in which:

FIGURE 1 is an end elevational View, certain parts being omitted, showing one method of and apparatus for forming an end seal on a filter element of the star type;

FIGURE 2 is a perspective view, largely diagrammatic, showing a modified method of forming a filter element of the star type;

FIGURE 3 is a detail view showing yet another modified method of forming a filter element;

FIGURE 4 is a detail view, broken-away, showing another form of end seal for a filter element exemplifying the present invention;

FIGURE 5 is a diagrammatic view, partly broken-away, showing yet another method of providing an end seal on a filter element;

FIGURE 6 is a view, partly broken-away, showing diagrammatically and in section a filter element of the fan type in which the folds of the pleats extend radially and showing the formation of the inner and outer seals at the ends of the pleats;

FIGURE 7 is a detail view showing a modification in a filter element of the type shown in FIGURE 6;

FIGURE 8 is a partly sectional and exploded view showing a filter element of the fan type having an inner tube secured to the inner edges of the pleated filter material;

FIGURE 9 is a perspective view partly broken-away showing a filter element of the spiral type.

Referring first to FIGURE 1, this shows one method of spraying the adhesive on to the edges of the filter material, as applied to the construction of a filter element of the star type. This element is formed of a strip of filter material 2, such as paper, which is pleated and formed into an annulus as shown, the ends of the strip being fastened together in any suitable way to complete the annulus.

In order to form an end closure for the element, the pleated annulus is mounted on a rotary carrier having a core 3, on which the annulus is fitted and by which it is rotated in the direction of the arrow. While the annulus is being rotated, the adhesive substance is sprayed on to the end edges of the filter material and, in FIG- URE 1, this is shown as being done by means of two spray guns 4 and 5, two guns being used for speed in production although a single gun would sufiice.

Each of the spray guns includes a spray nozzle 11 which is supplied with a liquid adhesive through a pipe 6 and with air under pressure through a pipe 7. The pipes shown at 8 are control lines leading from an external control (not shown) to control valves within the guns 4 and 5 so that operation of the control starts and stops the operation of the guns.

When the guns are operated adhesive supplied through the pipes 6 is entrained and atomised by the air delivered through the pipes 7 and is discharged through the nozzles 21 in the form of fan-like sprays 9 at an oblique angle to the end of the filter element and laterally of the end edges thereof. Due to this angularity and position of these jets of sprayed adhesive, the adhesive is sprayed on to the end edges of the pleated filter material, where it builds webs bridging the end edges of the pleats and eventually forms a continuous film or layer 10 closing the spacing between said pleats. This layer 10 connects and forms a seal between the adjacent edges of the filter material 2 and, when allowed to build up to a proper thickness, renders it unnecessary to provide a separate end cap.

It will be understood that, if a single application of the spray is enough, the layer 10 will be formed after the annulus has completed only one half of a revolution about the axis of the core 3, but if, as will generally be the case, a number of applications of the adhesive are necessary or desirable the annulus may be caused to make one or more complete revolutions before the spray is cut oti and the annulus is removed.

As an adhesive, it is preferred to use a substance which will retain a degree of resiliency after setting, such as natural or synthetic rubber (the latter being generally preferred, particularly when there is any possibility of oil reaching the filter element or if the latter is intended for filtering oil). An example of a suitable material is a nitrile synthetic rubber, such as that which is manufactured by The Goodyear Tyre & Rubber Company and which is hold under the name Pliobond. Another suitable synthetic rubber composition is that known as Boscoprene 2413 which is supplied by The BB. Chemical company.

It is also possible to use synthetic plastics for the adhesive, such as acrylic resins. One example incorporates n-butyl methacrylate. This provides a transparent seal.

The nozzles n, through which the jets of adhesive are discharged against the end of the pleated annulus, are inclined at an angle to the plane of this end of the annulus, as can be seen from FIGURE 1. This angle is so selected that the adhesive adheres principally to the edges of the filter material and only penetrates to a limited and controlled extent between the pleats. The angle will be determined by the nature and consistency of the adhesive used and by the distances between the edges of the pleats.

Experiments have shown that with annular, star-type filter elements of the conventional sizes, such as are usually used as oil or air filters for the engines of motor road vehicles, an average angle of about 65 between the direction of the jets and the end plane of the filter element produces the best results, although the angle may vary between limits such as 60 to 65 or 60 to 70". In other cases, particularly when the distance between the edges of the pleats becomes large, the angle may be further reduced to perhaps 55 or even less.

The application of the adhesive may be effected by rotating the pleated annulus in front of (or beneath) a jet or jets, which is or are arranged to spray the adhesive over the entire radial thickness of the pleated material, as shown in FIGURE 1, and small jets or nozzles With a fan-like discharge may be used as shown in this figure. In certain cases, however, an elongated or slitlike nozzle may be used and an example of this is shown diagrammatically in FIGURE 2.

In FIGURE 2, the pleated annulus 11 is shown as being mounted and rotated beneath a slit-like nozzle, which is indicated diagrammatically at 12. This nozzle 12 is so designed as to discharge the adhesive evenly over the end edges of the pleated material.

As has been indicated above, it is desirable, for best results, that the angle between the jet of adhesive and the plane, containing the edges of the pleated filter material, should be smaller where the distances between the pleats are large (which they are near the outer edge of the annulus) than where these distances are smaller (as is the case nearer the centre of the annulus); and FIGURE 2 shows one method of doing this when a slit-like nozzle 12 is used. This is done by making the angle between the direction of the jet and the plane, containing the edges 13, greater near the centre than it is near the periphery of the annulus or, in other words, by making the angle of the jet with respect to the longitudinal axis of the filter element less near the centre than near the periphery. If, for example, the angle a shown in FIGURE 2 is made 25 while the angle b is made 35 the angle between the direction of the jet and the plane of the edges '13 will be 65, while the corresponding angle at the periphery, where the pleats are further apart, will be only 55.

An alternative method of achieving a similar result would be by using a finer form of jet which is reciprocated radially during the rotation of the pleated filter material, it being possible during this radial movement to cause the angle of the jet relatively to the plane of the edges of the material to be varied. An example of how this may be done is shown purely diagrammatically in FIGURE 3.

In this case shown in FIGURE 3, the pleated filter material 21 is shown as being rotated past a spray nozzle 22. This nozzle is shown as being supported by a pair of guides 23 and 24, along which it is reciprocated by suitable means, not shown, during the rotation of the pleated annulus, so as to distribute the adhesive over the radial thickness of the latter. By arranging the guide 24 at a suitable angle to the guide 23, it is possible to ensure that the angle between the nozzle 22 and the plane of the edges of the material is greater when the nozzle is nearer the centre, as shown in full lines, than when it is near the outer edge of the annulus, as shown in broken lines.

It may be remarked here that although, for the sake of convenience, the adhesive has been shown in FIG- URES 2 and 3 as being directed downwardly on to the end of the pleated annulus, which is here shown horizontal, it may generally be preferred to have the plane of the end vertical and the axis of the annulus horizontal, as in the case of FIGURE 1.

In the filter elements which have been described so far it is intended that the closure of the ends of the spaces between the pleats should be effected solely by the film of adhesive itself, but it is possible for the adhesive to fulfil a further purpose as well. It may, for example, serve for attaching a label or the like. An example of this is shown in FIGURE 4. This shows a star type filter element having an annulus of pleated filter material 31 to which an end coating 32 is applied by spraying. This may be done by one of the methods which have been described with reference to FIGURES 1, 2 and 3. While the adhesive is still soft or liquid a label 33 is applied, which label may carry any suitable inscription or information. This label will be held in place by the adhesive when the latter dries and it will strengthen and protect the end of the filter element, although it will still be the adhesive which provides the seal to prevent fluid from escaping at the ends of the filter element.

In order to protect the label 33, it may be covered by means of a layer 34 of transparent material. This layer could simply consist of a varnish or the like or it could be formed of a transparent adhesive. An example of the latter is an acrylic resin, such as n-butyl methacrylate.

The same or a similar acrylic resin adhesive could also be used to form the actual sealing layer 32.

It is also possible, according to a further feature of this invention, to use an adhesive which is sprayed on to the edges of the filter material to secure a separate end cap or other closure. This may be done in the manner which has been described for the label 33 of FIG- URE 4 (but without the provision of a transparent covering layer 34). It is, however, preferred to utilise a method which is illustrated in FIGURE 5 in which the adhesive is sprayed simultaneously on to the edges of the filter material and on to the end cap, before the two are pressed together.

Referring to FIGURE 5, the pleated filter material is shown at 41, the pleated annulus being mounted on and rotated by a core 42 which is similar to the core 3 of FIGURE 1. This core 42 carrying the filter material is rotated by suitable means (not shown).

Supported spaced from but coaxial with the annulus 1 is an end cap 43, which may be formed of card or other suitable material. This is supported and rotated simultaneously with the pleated annulus by any suitable means, a holder for the end cap being indicated diagrammatically at 44.

A double nozzle 45 connected to a suitable spray gun (not shown) is fitted between the annulus 41 and the end cap 43 and while these are being rotated the adhesive is sprayed onto the edges of the filter material, as shown at 46, and on to the inner face of the end cap, Where it forms a film 47. The nozzle 45 is then withdrawn and the end cap is brought against the end of the pleated annulus, where it is secured when the adhesive hardens.

FIGURE 6 shows the application of the invention to filter elements of the fan type, such as are referred to above, in which the folds of the pleats extend radially. In FIGURE 6 the pleated filter material is indicated at 51 and the drawing shows the simultaneous production of an inner sealing layer 52, which may take the place of a separate inner tube, and of an outer sealing band 53, which may take the place of a separate rubber or other band.

As is indicated purely diagrammatically in FIGURE 6, the inner layer 52 may be formed by spraying the adhesive on to the inner edges of the filter material using a nozzle 54, while the outer layer 53 may be formed in a similar manner using a nozzle indicated at 55.

As is clearly shown in the drawing, the outer layer 53 is so formed that it includes upper and lower lips 56 and 6 57, which are shaped as shown. These both strengthen the filter element and also serve the very useful function of providing a seal against the appropriate parts of the filter casing in which the element is used.

In order to ensure the correct formation of these lips 56 and 57 additional nozzles, such as those indicated at 58 and 59, may be used.

FIGURE 7 shows a modification of the filter element of FIGURE 6, in that the upper lip is formed with an integral raised bead 60. This may be done by a suitable arrangement of the nozzle 58 and control of the amount of adhesive discharged by it.

The purpose of the raised bead 64) is to provide an improved seal with the filter casing.

Instead of relying on the adhesive to take the place of an inner tube, it may be used to attach a separate inner tube, such as is indicated in FIGURE 8. In this case the pleated filter material 61 has the adhesive sprayed on to its inner edges 62, where it may form a continuous film similar to layer 52 in FIGURE 6. While the adhesive of this film is wet the inner tube 63 is fitted in position, where it is held by the adhesive. Similarly, if it is desired to use a separate outer band (not shown) this may be secured in position by means of adhesive sprayed on to the outer edges 64 of the filter material.

FIGURE 9 shows a filter element which is similar to that shown in FIGURES 1 and 2 except that the filter material 71, instead of being pleated, is wound into a coil or spiral with the convolutions thereof spaced from each other. In this case the adhesive may be applied to the end edges 72 of the filter material by spraying. This may be done in a manner which may be similar to one of those which have been described except that in this case the jet or jets used should be directed radially, either towards or way from the central axis of the filter element.

I claim:

1. In constructing a filter element of sheet filteringmaterial formed into a shape having, at least, one end thereof provided with a plurality of adjacent edge portions which are spaced apart laterally from each other, the method of forming a closure for said end of the filter element to control the passage of fluid and to assure that the fluid, to be filtered, passes through the filter material, which method comprises discharging under pressure drop lets of an adhesive substance in form of a sprayed jet laterally of and onto said edge portions at an acute angle relative to a plane extending from one adjacent edge portion to the other, while causing relative rotary movement of the jet of said sprayed substance laterally with respect to the said edge portions to build webs of said substance bridging successively, during said relative movement, the spaces between said edge portions and embedding said edges therein; and continuing this operation until a layer is formed of desired thickness to form a continuous unbroken cover closure for said end of the filter element with said edges bonded therein, when said adhesive substance has hardened.

2. A method as set forth in claim 1, where said laterally spaced edge portions of the filtering element are at divergingly wider distances apart along their length from one end of adjacent edge portions to their other ends, said method being further characterized by arranging the acute angle, at which said jet of adhesive substance is sprayed to the plane extending between said edge portions, in a gradient of decreasing degrees from the regions where the adjacent edges are relatively closest together toward the regions where the edges are farthest apart.

3. A method as set forth in claim 1, wherein the said laterally spaced edge portions of the filter element are angulated relative to each other so that the ends of said edge portions are at greater distance apart at one of their ends than at their other ends; and wherein said method is characterized by causing a relative reciprocating movement between said jet spray of adhesive substance and said filter element the general direction in which said edges extend, during the aforesaid relative rotary movement of said filter element with respect thereto, and varying said acute angle of said jet, during said reciprocating movement, to gradually decrease the acute angularity of said jet as the distance between adjacent edge portions increases in one direction of said reciprocating movement of said jet and to increase said acute angularity of said jet as the distance between adjacent edge portions decreases in the other direction of said reciprocating movement of said jet.

4. A method according to claim 1, further characterized by applying reinforcing members of sheet material to the outer exposed surface of said closure of adhesive substance before said substance hardens, whereby said member becomes bonded thereto upon the hardening or setting of said adhesive.

5. A method as set forth in claim 1, including the step of aligning an annular reinforcing end-cap axially with the end of the filter element to be sprayed; then rotating and spraying the face of said end-cap, opposing said end of said filter element, with said adhesive substance simultaneously with and while said end of said filter is being sprayed, and then moving said cap into engagement with the sprayed end of said filter element with their adhesivebearing surfaces in adhering contact.

6. In constructing a filter element of sheet filtering-ma terial formed into a pleated annular form with said pleats being substantially of equal length and the distance varying between and along the end-edges of adjacent pleats; the method of forming a closure at the end-edges of said annular form to assure that fluid, to be filtered, passes through said filter material when placed in a proper housing, said method comprising closing the spaces between the end edges of said pleats by spraying a jet of an adhesive substance at varying acute angles, within a range approximately 55 to 70, to and laterally of said end edges of said pleats while rotating said filter element and said jet relatively to each other, said acute angles being a gradient of lessening degrees from where the end-edges of the pleats are closest together toward where they are farthest apart, and conversely, thereby to form webs bridging said spaces between the ends of said pleats until an unbroken continuous annular layer of said adhesive substance has built up upon and is covering the area of said annular form defined by the end edges of said pleats, and allowing said adhesive layer to harden to form a solid closure with the end edges embedded in and bonded to said solid closure.

7. In constructing a filter element of sheet filtering-material formed into a pleated annulus having the pleats extending radially thereof, the method of forming a closure at the circumferences of said annulus to assure that fluid, to be filtered, passes through the filter material; said method comprising closing the spaces between the end edges of said pleats at the inner and outer circumferences of said filter element by spraying jets of an adhesive substance toward the said circumferences onto and laterally of said end edges of said pleats at varying acute angles according to the varying distances between said end-edges while causing rotation of said circumferences and said jets relatively to each other to form webs bridging said spaces between the ends of said pleats until said circumferences of the annulus are provided with an unbroken continuous annular layer of said adhesive substance with said end edges bonded into said layer.

8. A method according to claim 6, including similarly positioning and simultaneously applying at least one jet of said adhesive onto and around a corner of said end edges to form a lateral continuous corner lip on at least one side edge of said pleats of said filter element and homogeneous with the layer of said adhesive substance on the end-edges of said pleats.

References Cited in the file of this patent UNITED STATES PATENTS 1,457,625 Freyberg June 5, 1923 2,642,187 Bell June 16, 1953 2,732,031 Rabbitt Jan. 24, 1956 2,739,916 Parker Mar. 27, 1956 2,843,218 Kickhaefer July 15, 1958 3,025,963 Bauer Mar. 30, 1962 FOREIGN PATENTS 747,780 Great Britain Apr. 11, 1956 OTHER REFERENCES Todd, W.D.: Plastisol Viscosity-Temperature Characteristics, reprint from Modern Plastics, September 1956, 13 pages.

Baird, D. K.: P. V. C. Paste, British Plastics, April 1948, pp. 167171.

Halofluorocarbon: Kel-F Dispersion, Bulletin H-JFCS (67.25) LP of the Minnestota Mining and Mfg. Co., received in the Patent Ofiice, Aug. 8, 1958.

Claims (1)

1. IN CONSTRUCTING A FILTER ELEMENT OF SHEET FILTERING, MATERIAL FORMED INTO A SHAPE HAVING, AT LEAST, ONE END THEREOF PROVIDED WITH A PLURALITY OF ADJACENT EDGE PORTIONS WHICH ARE SPACED APART LATERALLY FROM EACH OTHER, THE METHOD OF FORMING A CLOSURE FOR SAID END OF THE FILTER ELEMENT TO CONTROL THE PASSAGE OF FLUD AND TO ASSURE THAT FLUD, TO BE FILTERED, PASSES THROUGH THE FILTER MATERIAL, WHICH METHOD COMPRISES DISHCARGING UNDER PRESSURE DROPLETS OF AN ADHESIVE SUBSTANTCE IN FORM OF A SPRAYED JET LATERALLY OF AND ONTO SAID EDGE PORTIONS AT AN ACUTE ANGLE RELATIVE TO A PLANE EXTENDING FROM ONE ADJACENT EDGE PORTION TO THE OTHER, WHILE CAUSING RELATIVE ROTARY MOVEMENT OF THE JET OF SAID SPRAYED SUBSTANCE LATERALLY WITH RESPECT TO THE SAID EDGE PORTIONS TO BUILD WEBS OF SAID SUBSTANCE

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