GB2327624A

GB2327624A - Pleated filter elements

Info

Publication number: GB2327624A
Application number: GB9815587A
Authority: GB
Inventors: Peter Francis Bradford
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1997-07-26
Filing date: 1998-07-20
Publication date: 1999-02-03
Also published as: GB9815587D0

Abstract

A filter suitable for separating contaminants from the supply of fuel to an internal combustion engine comprises a pleated filter element 18 with a plurality of first folds (24, fig 2) lying on one plane and a plurality of second folds (28, fig 2) lying on another, the two planes being parallel to one another. The filter element is supported by a pair of plates 10,12 which define a unit of generally square or rectangular cross section. The filter element is provided with an additional plurality of folds (68, fig 8) in a direction perpendicular to the first and second folds. The filter element can be replaced when clogged, or alternatively the entire unit can be replaced. Preferably a water repellant screen is provided, the water present in the fuel collecting in a chamber at the base of the unit (48, fig 6), and air bubbles rising to an air collection chamber (62, fig 6).

Description

FILTER This invention relates to a filter, and in particular to a filter suitable for separating contaminants from the supply of fuel to a compression ignition internal combustion engine.

A known filter comprises a generally cylindrical housing within which a pleated paper filter element is located. The folds of the filter element lie substantially parallel to the axis of the housing. In use, fuel flows through the filter element from an outer radial position to an inner radial position, contaminants carried by the fuel being unable to pass through the filter element. Such a filter element is illustrated in Figure 1.

It is desirable to improve the efficiency and useful working life of filters by increasing the area of the filter element available for fuel to flow through.

In the arrangement illustrated in Figure 1, for given inner and outer diameters, the area of the filter element can only be increased by increasing the number of pleats. However, as the number of pleats is increased, the pleat separation is reduced, and this can have an adverse effect upon the efficiency of the filter, particularly adjacent the inner diameter of the filter element as this is where the pleat separation is smallest, as the reduced pleat separation restricts fuel flow through the filter.

According to the present invention there is provided a filter including a pleated filter element, the filter element having a plurality of first folds, the crests of the first folds lying substantially on a first plane and a plurality of second folds, the crests of the second folds lying substantially on a second plane, wherein the first and second planes are parallel to one another.

As the folds of the filter element are located upon parallel planes, the filter element can be received within a housing of square or rectangular crosssectional shape, the first and second planes extending parallel to the walls of the housing.

The filter element may further be provided with a plurality of additional folds, each fold extending in a direction substantially perpendicular to the first and second folds. Such an arrangement permits a further increase in the available filtration area without increasing the dimensions of the filter.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic sectional view illustrating a conventional pleated filter element; Figure 2 is a view similar to Figure 1 illustrating a filter element forming part of an embodiment of the invention; Figure 3 is a perspective view, part broken away, illustrating a filter cartridge including the filter element of Figure 2; Figure 4 is an enlarged sectional view of part of the cartridge of Figure 3; Figures 5a, 5b, 5c, 5d and 5e are views similar to Figure 4 showing modifications to the filter element; Figure 6 is a diagrammatic sectional view of a filter incorporating the filter element of Figure 2; Figure 7 is a view similar to Figure 6 of an alternative filter; and Figure 8 is a view similar to Figure 3 illustrating a modification.

Figure 3 illustrates a filter cartridge which comprises upper and lower support plates 10, 12, each of which is of substantially square crosssectional shape. The outer edge of each of the support plates 10, 12 includes a lip 14, 1 6. A pleated paper filter element 18 is located between the upper and lower support plates, the outer edge of the filter element 18 being located by the lips 14, 16 of the upper and lower support plates 10, 12. The inner edge of the pleated paper filter element 18 is guided by means of a perforated tubular member 20 which is of generally square cross-sectional shape. The tubular member 20 interconnects the upper and lower support plates 10, 12. As illustrated in Figure 3, the upper support plate 10 is provided with a tubular projection 22 which defines a passage through the upper support plate 10 which communicates with a chamber defined by the tubular member 20.

The pleated paper filter member 18 takes the form of an elongate strip of paper filter material, the ends of which are sealed to one another using an appropriate adhesive or using a direct compression technique. The paper filter material is folded in a direction perpendicular to the length of the strip to define a plurality of pleats. As illustrated most clearly in Figures 2 and 4, the pleated paper medium forms four rows of pleats, each row extending adjacent a respective outer edge of the filter cartridge. For each row of pleats, the filter medium includes a plurality of first, outer folds 24 the crests of which lie upon a first plane 26 which extends parallel to and adjacent the outer periphery of the filter cartridge, and a plurality of second folds 28 the crests of which lie upon a second plane 30 which is parallel to but spaced from the outer periphery of the filter cartridge. As shown in Figure 4, the second plane 30 extends parallel to and adjacent the outer surface of the tubular member 20. The first and second planes 26, 30 are substantially parallel to one another.

As shown most clearly in Figures 2 and 4, of the four rows of pleats, first and second rows 32, 34 are relatively long, third and fourth rows 36, 38 being shorter. The first and second rows 32, 34 extend adjacent the ends of the third and fourth rows 36, 38. It will be appreciated that such an arrangement utilizes the space adjacent the corners of the filter cartridge in an efficient manner. However, other arrangements are envisaged for the form of the pleats in the corner regions of the filter cartridge. Such modifications are illustrated in Figures 5a 5 > , 5c, 5d and 5e.

In the arrangement of Figure 5a, the filter element 18 includes a pair of panels 40 of filter medium which extend adjacent the outer periphery of the filter cartridge, the panels 40 interconnecting the ends of the rows of pleats adjacent the sides of the filter cartridge. The arrangement of Figure 5b differs from that of Figure 5a in that the panels 40 are spaced from the outer periphery of the filter cartridge. In the arrangement of Figure 5c, the rows of pleats are interconnected by a series of pleats having panels 42 which are of relatively short width, these panels extending around the intersection of the rows of pleats. Figure 5d illustrates an alternative construction in which the pleats at the intersection of the rows of pleats are of increased width, but a reduced number of pleats are provided.

Figure 5e illustrates an arrangement which is similar to that of Figure 4 but in which the pleats at the ends of the third and fourth rows 36, 38 are of reduced width providing improved flow access to the end pleats of the first and second rows 32, 34.

Figures 6 and 7 illustrate filter arrangements including a filter cartridge similar to that illustrated in Figures 2, 3 and 4. In the arrangement of Figure 6, the filter cartridge is located within a housing 44 of substantially square cross-section, the housing 44 defining a step 46 upon which the filter cartridge is located, the part of the housing 44 beneath the step 46 defining a water collection bowl 48. The cross-sectional area of the housing 44 is sufficiently large to define an outer chamber 50 between the housing 44 and outer periphery of the filter cartridge, and an appropriate seal 52 is located upon the shoulder 46 in order to avoid fuel flow directly between the chamber 50 and water collection bowl 48.

A lid assembly 54 is sealed to the upper periphery of the housing 44, the lid assembly 54 including an inlet port 56 which communicates with the chamber 50, and an outlet port 58 which is sealed to the projection 22 provided on the upper support plate 10 of the filter cartridge. A baffle 60 is located within the tubular member 20 of the filter cartridge, the baffle 60 and tubular member 20 defining an air collection chamber 62 which communicates with the interior of the projection 22 through a small orifice 64.

In use, fuel supplied through the inlet port 56 flows to the chamber 50, the fuel then flowing through the filter medium of the filter cartridge.

Contaminants carried by the flow of fuel are trapped by the filter medium, the clean fuel continuing through the perforations of the tubular member 20. Air and water carried by the flow of fuel also pass through the filter medium, the water tending to agglomerate into small droplets. The fuel, water and air passing through the perforations of the tubular member 20 enters a chamber defined between the tubular member 20 and the baffle 60. In order to exit from the filter arrangement, the fuel must flow downwardly around the baffle 60 and then flow upwardly in order to reach the outlet port 58. Water flowing with the fuel also flows downwardly, but due to the higher density of the water compared to the diesel fuel, the water tends to continue flowing downwardly, flowing through an opening provided in the lower support plate, and collecting in the water collection chamber 48 rather than flowing upwardly towards the outlet port 58. Air flowing with the flow of fuel to the chamber defined between the tubular member 20 and baffle 60 tends to rise, collecting within the air collection chamber 62, and air from the air collection chamber 62 is able to pass through the small orifice 64 in a controlled manner to continue with the flow of fuel through the outlet port 58 as a series of small air bubbles.

The arrangement of Figure 7 is similar to that of Figure 6, but in the Figure 7 arrangement, the lower support plate 12 does not include a central opening, thus water passing through the filter element is not able to reach the water collection bowl 48. Rather, the filter cartridge is not sealed to the shoulder 46, and the outer periphery of the filter cartridge is provided with a suitable water-repellant screen, or the filter material itself may be formed by a material having water-repellant properties. The presence of the water-repellant screen separates water from the flow of fuel, fuel passing through the filter medium whilst water continues to flow downwardly through the chamber 50, and beneath the filter cartridge to collect in the water collection bowl 48. Air continues with the flow of fuel, and collects in the air collection chamber 62 as described herei nbefore.

In the arrangements of Figures 6 and 7, fuel flows from an outer chamber to an inner chamber, but it will be appreciated that the connections to the filter could be reversed so that fuel flows from the interior of the filter cartridge towards the chamber 50. In such an arrangement, the location of the small orifice 64 would be altered to that indicated at 64a in Figure 7 to ensure that the air bubbles continue with the flow of fuel through the outlet port.

It will be appreciated that the filter is suitable for use in a number of applications. Any suitable technique may be used to secure the filter in position. In the arrangements of Figures 6 and 7, the filter takes the form of a removable filter cartridge located within a housing. However, it will be appreciated that other arrangements are possible, for example an arrangement in which the filter element is fixed within the housing, and when replacement of the filter element is required, the assembly of the filter element and housing is replaced with a new filter element and housing assembly. Any appropriate means may be used to secure the housing to the filter head, both in the arrangements of Figures 6 and 7 and in the modifications described hereinbefore.

The arrangement illustrated in Figure 8 is similar to that of Figure 3, but differs in that the filter medium is provided with a plurality of further folds 68 which extend in a direction substantially perpendicular to the first and second folds 24, 28. It will be appreciated that the provision of the further folds 68 enables an increase in the available filtration area by permitting an increased amount of filter material to be received with a filter housing of a particular size. Alternatively, the filter housing may be of reduced dimensions without reducing the available filtration area.

Other than with regard to the provision of the further folds 68, the filter illustrated in Figure 8 is identical to that of Figure 3 and will not be described in further detail. It will be appreciated that any of the modifications described hereinbefore may be incorporated into the arrangement of Figure 8.

Claims

1. A filter comprising a pleated filter element, the filter element having a plurality of first folds, the crests of the first folds lying substantially on a first plane and a plurality of second folds, the crests of the second folds lying substantially on a second plane, wherein the first and second planes are parallel to one another.

2. A filter as claimed in Claim 1, wherein the filter element is supported by a pair of support plates, the support plates and filter element together defining a unit of substantially square cross-sectional shape.

3. A filter as claimed in Claim 1 or Claim 2, wherein the filter element is further provided with a plurality of additional folds, each additional fold extending in a direction substantially perpendicular to the first and second folds.

4. A filter substantially as hereinbefore described with reference to any one of Figures 2 to 8 of the accompanying drawings.