GB2367257A

GB2367257A - An oil filter for an internal combustion engine

Info

Publication number: GB2367257A
Application number: GB0119039A
Authority: GB
Inventors: George Mansfield Stuart
Original assignee: Risbridger Ltd
Current assignee: Risbridger Ltd
Priority date: 2000-08-04
Filing date: 2001-08-03
Publication date: 2002-04-03
Anticipated expiration: 2021-08-03
Also published as: GB0019278D0; GB0119039D0; GB2367257B

Abstract

An oil filter for an internal combustion engine which comprises a housing 1 having an inner compartment 5 and a concentric outer compartment 16, separated by a cylindrical filter element 6. The outer compartment 16 is arranged to receive oil at high pressure from the engine and the inner compartment 14 is arranged to receive filtered oil for return to the engine or vice versa. The inner compartment 5 is formed by an axially extending hollow spool 7 which is adapted to mount the housing 1 on the engine. In use, oil from the engine enters the outer compartment 16 through apertures 18 in an end cap 3, passes radially through the filter element 6 and is withdrawn through passageway 5 back to the engine.

Description

OIL FILTER This invention relates to an all filter for an internal combustion engine.

I I ine.

Normally, oil filters are fitted to the outside of an engine block and contain an oil filter element within a metal casing. Commonly, the whole oil filter including the casing is diposed of at pre-set service intervals and replaced with a fresh unit which involves significant environmental hazards as well as wastage. At the time when the oil filter is replaced, it is also necessary to drain off and discard the oil in the engine. For high performance motor vehicles, special oils are used which are expensive so that unnecessary replacement constitutes a substantial waste.

One object of the present invention, therefore, is to provide an oil filter assembly for a motor car having improved filtering characteristics and involving less likelihood of environmental pollution.

According to the present invention there is provided an oil filter for an internal combustion engine which comprises a housing having an inner compartment and a concentric outer compartment, separated by a cylindrical filter, the outer compartment being arranged to receive oil at high pressure from the engine and the inner compartment being arranged to receive filtered oil for return to the engine or vice versa, the inner compartment being formed by an axially extending hollow spool which is also adapted to mount the housing on the engine. Preferably the housing comprises a cylindrical body with a cap at one end which is adapted to seat against the engine block, and the assembly is held together by the spool.

The spool may also be adapted to house a differential pressure detector in such a way that it is connected to the inner and/or outer compartments, the detector having an indicator part which is moveable to a visible position on detection of an unusual increase in differential oil pressure, thereby giving a visual warning of filter blockage.

Preferably, the detector includes either or both a temperature-sensitive retaining means and an automatic resetting feature so that cold engine start up conditions which may produce temporary high differential pressures do not preclude operating temperature indication.

The detector is preferably in the form of a cartridge which is received in the top of the oil filter housing.

One embodiment of an oil filter in accordance with the invention will now be described with reference to the accompanying drawings, in which: Figure I is a longitudinal section through an oil filter unit in accordance with the invention ; and Figure 2 is a longitudinal section through one form of a differential pressure indicator.

Referring to Figure 1 of the drawings, the oil filter unit comprises a housing (1) having a thin cylindrical body (2) which is axially finned to increase cooling of oil which passes through the unit. In order to assist the cooling affect, a flow of air may be directed onto it from the engine cooling fan. The housing (1) has an end-cap (3) into which it is seated by means of an 0-ring 4, and the end cap is provided with a sealing ring 5 which in turn, seats against the engine block.

The housing and end cap are held together in the assembled condition, by means of a central spool 7, which passes axially through the centre of the housing and is formed with a hexagonal cap 8 at its outer end which seats against the outer end of the housing.

The inner end of the spool is formed with an internal thread 11, so that it can be spun onto a mating spigot which is provided as a standard fitting on the engine block, and has an external annular recess 10 to receive a circlip 12. This is used to retain the end cap and

the housmg m the assembled condition, before the entire assembly is screwed onto the block.

Mounted within the housing (1) is a filter element (6). This is generally cylindrical in form having a central passage (5) through which the spool 7 passes, and the spool has apertures 14 through which filtered oil is recovered for rectum to the engine. The filter is preferably of cylindrical cartridge form having high quality filter material such as 15 micron fibreglass folded in concertina or pleated form around a central cylindrical tube. For example it may be an aerospace quality hydraulic filter. In use, oil from the engine enters the outer compartment (16) through apertures (18) in the end cap, passes radially through the filter (4) and is withdrawn through passageway (8) back to the engine.

Instead of a closed hexagonal cap as indicated at (8), the outer end of the spool may be formed with a cap having a through bore with an internal thread as indicated at (20), so that a differential pressure detector (22) (not shown in Figure 1) can be screwed into the cap in order to accurately sense the filter cartridge condition. One type of such detector (22) is illustrated in Figure 2.

The pressure detector (22) is in cartridge form and incorporates an indicator sleeve (24) which, in its normal condition, is retracted in the condition shown in Figure 2.

Optionally, the detector includes a transparent cover (17) through which the sleeve can be viewed. The detailed construction of the pressure detector is shown in Figure 2.

The pressure detector (9) is connected by passageways (12a & 12b) to the high and low pressure sides of the oil filter so that it can detect any unusually large difference in pressures between the high and low pressure chambers of the filter. The body (20) of the pressure differential indicator has an internal piston (13) which is urged upwardly by a spring (14). Piston (13) however includes a magnetic core (15) which retains a sleeve

(16) yin the tower part of a transparent cover (17) until the pressure differential between the inner and outer chambers in the filter exceeds a predetermined amount. This amount is selected to be indicative of significant blockage of the filter cartridge. The lower part of cover (17) is provided with an opaque shield (18) so that in the position shown in Figure 2, the sleeve is not visible.

When a pressure differential indicative of blockage is attained, piston (13) is pushed downwards against the spring pressure. As the sleeve (16) incorporates a magnetic ring (19) having opposite polarity to the magnet (15), sleeve (16) is repelled upwardly and is seen as a red indicator in the upper, transparent part of the cover (17).

This gives a visual warning that the filter needs changing.

When the pressure differential is reduced below the spring setting the piston (13) returns and the indicator sleeve (16) is reset to the lower hidden position.

Because unusually high pressures can be generated during engine warm up, a bimetallic element in the form of an expanding ring (21) can be fitted. This provides greater restraining force on the piston (13), while the temperature of the engine is low.

Once the engine warms up, the bimetallic ring opens, releasing its hold on the piston.

Instead of a mechanical indicator of the kind shown in Figure 2, the pressure detector may alternatively incorporate a sender for a remote indicator, for example on the control panel of a vehicle.

The overall construction of the assembly is thus such that it can accommodate a much higher quality filter element than the paper types normally used in car engines while fitting into the standard mounting spigot, as well as providing an optional mounting for a pressure sensor so that the true condition of the oil can be monitored. In addition the body is finned axially to provide improved oil-cooling (although the tinning could also be circumferential), and the mainly"non-disposable"construction entails less wastage.

Claims

CLAIMS 1. An oil filter for an internal combustion engine which comprises a housing having an inner compartment and a concentric outer compartment, separated by a cylindrical filter, the outer compartment being arranged to receive oil at high pressure from the engine and the inner compartment being arranged to receive filtered oil for return to the engine or vice versa, the inner compartment being formed by an axially extending hollow spool which is also adapted to mount the housing on the engine.
2. An oil filter according to claim 1 in which the housing comprises an assembly including a cylindrical body with a cap at one end which is adapted to seat against the engine block, the assembly being held together by the spool.
3. An oil filter according to claim 2 in which ports are provided in the cap and the walls of the spool so as to enable the passage of oil between an outlet port and an inlet port of the engine via the ports in the cap, the body of the filler, the ports in the spool and the hollow interior of the spool.
4. An oil filter according to any preceding claim in which the spool is adapted to house a differential pressure detector adapted to provide a visible indication of an unusual increase in differential oil pressure so as to give a warning of filter blockage.
5. An oil filter according to claim 4 in which the pressure detector includes a mechanical indicator.
6. An oil filter according to claim 4 in which the pressure detector comprises a sender adapted to provide a signal for a remote indicator on a control panel.
7. An oil filter according to any of claims 2 to 6 in which the spool comprises retaining means at each end which are adapted to engage with the outer end of the housing, and the cap, respectively.
S. An oil filter according to claim 7 in which the retaining means at the outer end comprises an integral cap or annular projection.
9. An oil filter according to claim 7 in which the retaining means at the inner end comprises an annular recess housing a removable circlip to allow assembly and disassembly of the filter.
10. An oil filter according to any preceding claim in which the housing is formed with external cooling fins.
11. An oil filter substantially as herein described with reference to the accompanying drawings.