GB2195914A - Filter assembly - Google Patents

Abstract

A filter assembly for liquid fuel includes a head 10 in which are formed inlet and outlet passages 12, 14 and a screw-on type filter unit 22. The filter unit comprises a container 23 housing a filter element 28, the container being closed by an end closure plate 24 in which is formed a central threaded aperture 25. The filter unit is retained against a surface 16 of the head by a bolt 17 which extends through an opening 11 in the head 10 and has a passage 20, 21 to communicate with inlet passage 12. Unit 22 is thus removable from head 10 without relative rotation, which might be resisted by binding of sealing rings 29, 31. The top of passage 20 is closed by a plug 33, removable to allow air or water to be withdrawn. <IMAGE>

Description

SPECIFICATION Filter assembly This invention relates to a filter assembly for liquids more particularly but not exclusively, liquid fuel, the assembly being of the kind comprising a closure body which carries a screw threaded member, the closure body also defining inlet and outlet flow passages one of which extends within said screw threaded member and a filter unit which contains a filter element and which has an end closure plate having a threaded aperture in which said threaded member is engaged and at least one annular resilient seal member located intermediate the closure member and the closure plate.

Filter assemblies of the above type are well known in the art, the filter unit being known as a "screw on" or "spin on" type of unit.

The closure body in known assemblies is expensive to produce, the screw threaded member being in the form of a spigot which is secured in the body. Moreover, in the use of the assembly when it is required to change the filter element great difficulty is often experienced in removing the element because the closure body and closure plate tend to be held against relative rotation by the seal member, the material forming which tends to stick or bond itself to the adjacent surfaces.

The object of the invention is to provide a filter assembly of the kind specified in a simple and convenient form.

According to the invention in a filter as sembiy of the kind specified said screw threaded member comprises a bolt which extends through an aperture in said closure body for engagement within the aperture in the closure plate.

An example of a filter assembly in accordance with the invention will now be described with reference to the accompanying drawing which shows part of the assembly in sectional side elevation with the left hand portion of the drawing showing the parts of the assembly before being secured together, the fully assembled parts being shown in the right hand portion of the drawing.

Referring to the drawing the filter assembly comprises a closure body which is in the form of a flat plate 10 which has a thickness sufficient to enable it to withstand clamping loads as will be explained. The plate is provided with a central aperture 11 into which extends a first flow passage 12 formed in the body, the flow passage carrying a pipe nipple 13.

The body also defines a second flow passage 14 also provided with a nipple 15, the flow passage 14 extending to one face 16 of the plate at a position spaced outwardly from the aperture 11.

For location within the aperture there is provided a bolt 17 which is screw threaded at 18 and is provided with the usual form of hexagonal head 19. In addition the bolt defines an axial passage 20 and cross drillings 21 between the passage 20 and the exterior surface of the shank portion of the bolt intermediate the head and the screw threaded portion.

The filter assembly also includes a filter unit generally indicated at 22 and which comprises an outer container 23 of cup-shaped form the open end of which is closed by a closure plate 24 the centre portion of which is turned downwardly and is internally threaded to provide a threaded aperture 25. The closure plate intermediate its inner and outer peripheral surfaces is provided with openings 26 and surrounding the threaded portion is a tube 27 between which and the internal surface of the container 23 is located an annular filter element 28 which conveniently is formed from paper.

Mounted on the closure plate is an outer annular seal member 29, this being retained in a channel member 30 which is formed by a bent section of material which is rolled into a lip of the container. A second annular seal member 31 is located about the threaded aperture 25 and is conveniently retained in position by a plastics clip member 32. In the assembled condition the threaded portion 18 of the bolt is secured within the threaded aperture 25 and the bolt is tightened sufficiently to generate a clamping force which compresses the seal members 29, 31 between the adjacent surfaces of the closure plate and the body. Fuel can then flow for example through the flow passage 12 into the passage 20 of the bolt and then down through the tube 27 whereupon it rises through the element 28, any contaminant in the fuel being# retained in the element.From the element the fuel passes through the apertures 26 and into the annular space which is defined between the sealing members and the surface 16.

From this space it can pass through the passage 14 to the outlet 15. It will be understood however that the fuel can, if so required, flow in the opposite direction.

When it is required to change the filter element 22 it is a simple matter to undo the bolt 17 and then separate the plate 10 from the element. In known constructions it has been necessary to effect relative rotation between the plate and the element which rotation was resisted by the adhesion between the sealing members 29 and 31 and the surface 16. The replacement of an element is therefore simplified as also is the construction of the assembly.

It will be noted that the passage 20 extends completely through the bolt 17 and is closed by a sealing bolt 33. The sealing bolt can be removed to allow air to be displaced from the interior of the container and it may also be used to enable water collecting in the bottom of the container, to be extracted from the container by a vacuum pump.

It is envisaged that the filter assembly will be mounted by means of a metal or like strap secured around the container 23 but if desired, the plate 10 can be provided with an extension formed to constitute a mounting bracket. In addition, the flow passage 14 may extend at right angles to the surface 16 and the two flow passages can be disposed at any angular relationship relative to each other.

Claims (4)

1. A filter assembly for liquids comprising a closure body which carries a screw threaded member, the closure body defining inlet and outlet flow passages one of which extends within said screw threaded member, a filter unit comtaining a filter element and having an end closure plate having a threaded aperture in which said threaded member is engaged and at least one annular resilient seal member located intermediate the closure member and the closure plate, said screw threaded member comprising a bolt which extends through an aperture in said closure body for engagement with the threaded aperture in the closure plate.

2. An assembly according to Claim 1 in which said bolt is provided with an axial passage and a cross drilling said axial passage and said cross drilling forming part of said one flow passage.

3. A filter assembly according to Claim 2 in which said axial passage extends through said bolt and a sealing bolt engageable within a threaded portion of said passage to seal the end of the passage remote from the filter unit.

4. A filter assembly for liquids comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.