GB2162079A

GB2162079A - A filter for the lubricating oil or fuel of an internal combustion engine

Info

Publication number: GB2162079A
Application number: GB08515069A
Authority: GB
Inventors: Pavlin Jaroslav
Original assignee: Filterwerk Mann and Hummel GmbH
Current assignee: Mann and Hummel GmbH
Priority date: 1984-06-16
Filing date: 1985-06-14
Publication date: 1986-01-29
Also published as: FR2566045A1; GB2162079B; DE3422482A1; FR2566045B1; GB8515069D0

Abstract

A filter housing includes an inlet 16, main outlet 17 and a drainage duct 19 leading back to a sump. Removable cover 12 enables annular filter element 20 to be replaced, and the filter element engages a combination valve 40 to close the drainage duct from both sides of the element when the cover is screwed down. The valve includes a bypass valve member 54, which opens a path from chamber 33 to outlet 17 when the pressure across the filter element 20 rises. The valve further includes a main valve member which progressively rises when cover 12 is unscrewed (Figs. 3 to 5 not shown) so that the dirty contents of chamber 33 and the filtrate from chamber 34 flow into the drainage duct and eventually the main outlet 17 is connected to the drainage duct 19 via passage 36 to drain the housing completely. If no filter element 20 is fitted, the valve stays in the raised position and no pressure can build up, warning the operator. <IMAGE>

Description

SPECIFICATION A filter for the lubricating oil or fuel of an internal combustion engine The present invention relates to a filter for the lubricating oil or fuel of an internal combustion engine provided with a liquid storage tank, said filter device including a filter housing which is sealed at its upper end by means of a removable housing cover; an annular radially traversable filter insert which is removable for servicing purposes and which separates an unfiltered liquid chamber from a filtrate chamber in the filter housing; a duct for unfiltered liquid for supplying the liquid to be filtered; a filtrate duct for discharging the filtered liquid; a drainage duct which extends from the bottom of the filter housing and is connectable to the fluid storage tank; and a shut-off device which is associated with the drainage duct and exposes the drainage duct when the housing cover is loosened.

When a filter insert is removed from such a filter, it is possible to prevent liquid from being discharged accidentally because, when the housing cover is loosened, the contents of the filter housing already flow away automatically through the drainage duct into the liquid storage tank.

German Patent Specification No. 2 555 420 describes such a filter for lubricating oil. A hollow threaded bolt extends longitudinally through the interior of the filter housing. The lower end of the bolt engages in a bore formed in the housing base and serves to seal the drainage duct. A hollow bolt of such type is a relatively expensive component. If a filter insert is inadvertently not fitted, the user of the internal combustion engine cannot notice this fact initially. There is a danger of rapid damage occurring because of wear. No provision is made for a by-pass valve which would permit the congested or clogged-up filter insert to be by-passed in a manner known perse.

In the filter according to German Gebrauchsmuster (Utility Model) No. 1 747 251, the lower end face of the incorporated filter insert acts upon a valve body of a shut-off valve which is axially displaceable in a direction counter to a spring force. If the filter insert is removed from the filter housing, the valve body closes the filtrate duct which leads directly to the consumer unit. This arrangement prevents the internal combustion engine from being operated without a filter insert.

This known liquid is also not provided with a bypass valve.

It is an object of the present invention to improve the construction and function of such an abovedescribed liquid filter by the use of simple means so that the shut-off device can indicate when a filter insert has not been fitted and so that there is no need to provide a separate by-pass valve.

According to the present invention there is provided a filter device for filtering the lubricating oil orfuel of an internal combustion engine provided with a liquid storage tank, said filter device including a filter housing which is sealed at its upper end by means of a removable housing cover; an annular radially traversable filter insert which is removable for servicing purposes and which separates an unfiltered liquid chamber from a filtrate chamber in the filter housing; a duct for unfiltered liquid for supplying the liquid to be filtered; a filtrate duct for discharging the filtered liquid; a drainage duct which extends from the bottom of the filter housing and is connectable to the fluid storage tank; and shut-off device which is associated with the drainage duct and exposes the drainage duct when the housing cover is loosened, characterised by the following features: (a) the shut-off device comprises a shut-off valve having a first valve member which is axially displaceable in a direction counter to a spring force acting upon a first valve seat and which is kept in its closed position by the lower end face of the incorporated filter inserts; (b) the shut-off valve includes a second valve seat for a second valve body of a by-pass valve which combines with the shut-off valve to form a combination valve, said second valve body being axially displaceable in a direction counter to a spring force; (c) a filtrate branch duct extends into the drainage duct in the region of the combination valve;; (d) when a filter insert has been fitted, the combination valve closes the drainage duct upstream and downstream of the junction with the filtrate branch duct; and (e) above a pre-determined pressure, the by-pass valve connects the unfiltered liquid chamber to the filtrate branch duct.

The previously mentioned long bolt member which is expensive to manufacture is now eliminated. If a filter insert is inadvertently not fitted, this situation is immediately noticed because a pressure does not build-up in the liquid system. By combining the shut-off valve and the by-pass valve to form a combination valve, a simple, compact construction is produced.

The combination valve is particularly easy to manufacture and assemble because the first valve body is provided with a coaxial valve bore and the second valve seat for the second valve body, the valve shaft or stem of said second valve body cooperating, in the same way as a slide valve, with a first control or leading edge of the drainage duct disposed downstream of the junction with the filtrate branch duct, said valve stem closing said drainage duct when a filter insert is fitted and keeping said drainage duct open when the filter insert has been removed.

Afurther proposal of the present invention seeks to minimise the risk of unfiltered liquid passing into the filtrate branch duct when the filter insert has been removed, and such a proposal is characterised in that the first valve body is provided with a transverse aperture and co-operates, in the same way as a slide valve, with a second control or leading edge and a third control or leading edge of the drainage duct- between which edges the filtrate branch duct extends-in such a manner that, when a filter insert has been fitted, the filtrate branch duct is opened; when the filter insert is partially removed, the filtrate branch duct is initially closed; and, when the filter insert is further removed, the filtrate branch duct is opened again.

One embodiment of the invention seeks to ensure that no dirty liquid can pass into the filtrate branch duct and is characterised in that the drainage duct upstream of the junction with the filtrate branch duct is provided with a fourth control or leading edge which co-operates, in the same way as a slide valve, with the first valve body, and in that the four leading edges of the drainage duct are so disposed three-dimensionally and are so adapted to the first valve body and to the second valve body that initially, when the filter insert has been removed, only the drainage duct downstream of the junction with the filtrate branch duct is opened and the filtrate branch duct is closed, then the drainage duct upstream of the junction with the filtrate branch duct is also opened, and finally the filtrate branch duct itself is also opened again.

The combination valve manages with only one single valve spring because the valve spring of the by-pass valve is in the form of a compression spring and presses the second valve body against the first valve body and presses said first valve body against the incorporated filter insert.

A further proposal relates to such a liquid filter wherein the drainage duct includes the first valve seat for the axially sealed abutment of the first valve body. The proposal seeks to permit better absorption of the relatively large axial tolerances of the filter insert and is characterised in that the first valve body has, at its end facing the filter insert, a sleeve which is axially slidable between stop members and is pressed against the incorporated filter insert by a return spring which has a greater force than the valve spring and is supported on the first valve body.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a schematic, axial cross-sectional view of a filter; Fig. 2 is an enlarged view of a combination valve used in the filter of Fig. 1; and Figs. 3 to 5 illustrate the combination valve of Fig.

2 in different positions.

Afluid filter is illustrated in Fig. 1 and includes a vertically disposed, substantially cylindrical filter housing 10 which is provided at its upper, open end with an external threaded portion 11. A removable housing cover 12 is screw-connected to the external thread 11 by its internal threaded portion 13 and seals the filter housing 10 via the intermediary of a sealing ring 14 which is pressed against the upper end face of the filter housing. A hollow cover extension portion 15 extends centrally downwardly from the housing cover 12.

At its lower end face, the filter housing 10 is provided with a dirty liquid, i.e. unfiltered liquid, passage or duct 16 through which the liquid to be filtered is supplied, a filtrate duct 17 through which the filtered liquid is discharged, and a drainage duct 19 which may be connected to a liquid storage vessel (not shown); that is to say if, for example, the liquid filter is used for lubricating oil, said duct 19 may be connected to the oil sump of an internal combustion engine.

An annular filter insert 20 comprises a filter paper star 21 which is folded in a zig-zag manner and joined together to form a ring, the upper end face of said star 21 being sealed by a bonded or a glued-on end disc 22 and the lower end face of said star 21 being sealed by a glued-on cover ring 23. The cover extension 15 of the housing cover 12 engages in a recess 24 formed in the end disc 22 and, as a result, centres the filter insert 20 at its upper end. At the lower end, the outer walls of a socket 25 engages in a centering manner in the aperture 26 formed in the cover ring 23. The filter insert 20 is pressed against a housing shoulder portion 30 by means of a compression spring 27 in a sealed manner through the intermediary of a sealing ring 29.Compression spring 27 is in the form of a pressure spring and is supported at one end against the housing cover 12 and at the other end against the end disc 22. In the filter housing 10, the filter insert 20 separates a dirty or unfiltered fluid chamber 33, which surrounds said insert 20 and into which chamber 33 the unfiltered fluid inlet duct 16 discharges, from the filtrate chamber 34 from which the filtrate outlet duct 17 extends.

A filtrate branch duct 36 connects the filtrate duct 17 to the drainage duct 19 in the region of a shut-off device 37 which is in the form of a combination valve 40 and is associated with the drainage duct 19 in a manner which will be described more fully hereinafter.

The drainage duct 19 comprises four cylindrical duct portions having different diameters. One duct portion 42 having relatively large diameter extends downwardly from the unfiltered liquid chamber 33 and is connected to the uppermost duct portion 41.

The subsequent duct portion 43 has a slightly smaller diameter, and the lowermost duct portion 44 is provided with an even smaller diameter. A sleeve-like first valve body 45 is disposed in the duch portion 43 so as to be longitudinally slidable therein and forms a shut-off valve 47 with the offset or shoulder portion between the duct portions 42 and 43 which is in the form of a first valve seat 46. In the position illustrated in Fig. 2, a sealing ring 49 is pressed against the first valve seat 46 by a collar 50 of the first valve body 45, so that no unfiltered fluid can by-pass the shut-off valve 47 and pass into the filtrate duct 17 via the filtrate branch duct 36.

The first valve body 45 is provided with a valve bore 51 which widens to a larger diameter via a shoulder portion which is in the form of a second valve seat 52. A second valve body 53 abuts against the second valve seat 52 and forms, together with said second valve seat 52, a by-pass valve 54. The valve stem 55 of the second valve body 53 is guided in a longitudinally displaceable manner in the duct portion 44, and the end of said stem 55 is provided with a plurality of slidetongues or projections 56 which extend downwardly from lower end face 57.

A valve spring 59 is in the form of a compression spring and one end face abuts against the shoulder portion between the duct portion 43 and the duct portion 44 and the other end face abuts against a shoulder portion of the second valve body 53.

Four leading edges are formed in the drainage duct 19 and co-operate with parts of the first valve body 45 and of the second valve body 53, respectively. The inner edge of the shoulder portion between the duct portion 44 and the duct portion 43 forms a first leading edge 60 which co-operates with the sliding edge 61 of the valve stem 55. A second leading edge 62 is formed by the lower edge of the junction between the filtrate branch duct 36 and the drainage duct 19, and a third leading edge 63 is formed by the upper edge of the junction between the filtrate branch duct 36 and the drainage duct 19.

Finally, the inner edge of the shoulder portion between the duct portion 42 and the duct portion 43 is additionally provided as the fourth leading edge 64. The second leading edge 62 co-operates with the sliding edge 65 which is formed at the lower end face of the first valve body 45.

In the end facing the filtrate branch duct 36, the first valve body 45 is provided with a transverse aperture 66, the lower transition region of which aperture extends to the outer cylinder face and forms sliding edge 67, and the upper transition region of which aperture extends to the outer cylinder face and forms sliding edge 69. The first valve body 45 is non-rotatably guided in the drainage duct 19 in known manner, such as, by means of an axis-parallel extending groove and tongue-and-groove joint means (not shown).

On the end face facing the filter insert 20, a bush like or sleeve-like member 70 is provided with a plurality of arms 71 which are uniformly distributed over the circumference, the outwardly orientated feet 72 of said arms 71 engaging behind the shoulder between the duct portion 42 and the duct portion 41 and which shoulder is in the form of stop member 75. A return spring 73, which is in the form of a compression spring and is supported on the collar 50 of the first valve body 45, presses the member 70 against the filter insert 20 via a disc 74. A stop member 76 prevents the disc 74 from sliding away from the first valve body 45.

The compression springs used in the filter illustrated in Figs. 1 to 5 are adapted so that, when the filter insert 20 has been fitted, the compression spring 27 exerts a greater force than the return spring 73 and, in turn, the return spring 73 exerts a greater force than the valve spring 59.

When the filter insert 20 has been fitted as illustrated in Figs. 1 and 2, the shut-off valve 47 and the by-pass valve 54 are closed. The liquid to be filtered passes through the dirty or unfiltered liquid duct 16 into the dirty or unfiltered liquid chamber 33 and traverses the filter insert 20 radially from outside to inside. The filtered liquid leaves the filter housing 10 through the filtrate duct 17.

If the differential pressure between the dirty liquid chamber 33 and the filtrate chamber 34 exceeds a pre-determined level - if the filter insert becomes congested, for example, - the by-pass valve 54 is opened due to the second valve body 53 being displaced from the second valve seat 52, and liquid may by-pass the filter insert 20 and pass into the filtrate duct 17 to the consumer unit via the valve bore 51, the transverse aperture 66 and the filtrate branch duct 36.

If the filter needs to be serviced, the housing cover 12 is loosened by rotating it in the unscrewing direction. This causes the pressure on the filter insert 20 to be reduced by the compression spring 27, and finally the filter insert 20 is raised by the pressure of the return spring 73 until the disc 74 abuts against the stop member 76 of the first valve body 45. When the housing cover 12 is loosened further, the valve spring 59 pushes the filter insert 20 further upwardly. The filter insert 20 and the combination 40 eventually reach the position which is illustrated in Fig. 3 and in which the shut-off valve 47 and the drainage duct 19 downstream of the junction with the filtrate branch duct 36 are opened, but the transverse aperture 66 and the filtrate branch duct 36 itself are closed. In this position, neither dirty liquid nor filtrate flows away.

If the housing cover 12 is rotated further in the unscrewing direction, the filter insert 20 and the combination valve 40 eventually reach a position which corresponds to the position illustrated in Fig.

4. The drainage duct 19 is now opened both upstream and downstream of the filtrate branch duct 36. Liquid to be filtered may flow from the filtrate branch duct 36. Liquid to be filtered may flow from the dirty fluid chamber 33 and filtered liquid may flow from the filtrate chamber 34 past the arms 71 of the sleeve 70 through the annular gap between the wall of the duct portion 42 and the collar 50 and through the transverse aperture 66 into the valve bore 51 and thence through the coils of the valve spring 59 and through the gaps between the slide projections 56 into the drainage duct 19 for discharge into the liquid storage tank (not shown).

In this position, the filtrate branch duct 36 itself is closed and, as a result, no dirty liquid can enter the filtrate duct 17.

When the housing cover 12 is loosened even further, the valve spring 59 eventually pushes the filter insert 20 into the position illustrated in Fig. 5.

The filtrate branch duct 36 is now also opened and, as a result, the filtrate duct 17 may discharge into the drainage duct 19 via the filtrate branch duct 36.

After the filter housing 10 has been fully drained, the filter insert 20 may be removed without the risk of the slightest amount of fluid emerging.

If the housing cover 12 is screwed-on again after the insertion of a cleaned or new filter insert 20, the operational procedures are performed in the reverse sequence until eventually the position illustrated in Figs. 1 and 2 for normal operation is reached again.

If the filter housing i 0 were inadvertently closed by screwing-on the housing cover 12 without a filter insert 20 having been previously inserted, the combination valve 40 would remain in the position as illustrated in Fig. 5. Liquid entering the filter housing 10 would be permitted to flow away through the drainage duct 19. It would be possible for a conventional pressure gauge to indicate to the user the absence of any build-up of pressure in the system possibly resulting from the absence of a filter insert.

Claims

1. A filter device for filtering the lubricating oil or fuel of an internal combustion engine provided with a liquid storage tank, said filter device including a filter housing which is sealed at its upper end by means of a removable housing cover; an annular radically traversable filter insert which is removable for servicing purposes and which separates an unfiltered liquid chamber from a filtrate chamber in the filter housing; a duct for unfiltered liquid for supplying the liquid to be filtered; a filtrate duct for discharging the filtered liquid; a drainage duct which extends from the bottom of the filter housing and is connectable to the fluid storage tank; and a shut-off device which is associated with the drainage duct and exposes the drainage duct when the housing cover is loosened, characterised by the following features: (a) the shut-off device comprises a shut-off valve having a first valve member which is axially displaceable in a direction counter to a spring force acting upon a first valve seat and which is kept in its closed position by the lower end face of the incorporated filter inserts; (b) the shut-off valve includes a second valve seat for a second valve body of a by-pass valve which combines with the shut-off valve to form a combination valve, said second valve body being axially displaceable in a direction counter to a spring force; (c) a filtrate branch duct extends into the drainage duct in the region of the combination valve;; (d) when a filter insert has been fitted, the combination valve closes-the drainage duct upstream and downstream of the junction with the filtrate branch duct; and (e) above a pre-determined pressure, the by-pass valve connects the unfiltered liquid chamber to the filtrate branch duct.

2. A filter as claimed in claim 1, wherein the first valve body is provided with a coaxial valve bore and the second valve seat for the second valve body, the valve stem of said second valve body co-operating, in the same way as a slide valve, with a first control or leading edge of the drainage duct disposed downstream of the junction with the filtrate branch duct; said valve stem closing said drainage duct when a filter insert is fitted and keeping said drainage duct open when the filter insert has been removed.

3. A filter as claimed in claim 2, wherein the first valve body is provided with a transverse aperture and co-operates, in the same way as a slide valve, with a second leading edge and a third leading edge of the drainage duct- betweer which second and third leading edges the filtrate branch duct extends ~in such a manner that, when a filter insert has been fitted, the filtrate branch duct is opened; when the filter insert is partially removed, the filtrate branch duct is initially closed and, when the filter insert is further removed, the filtrate branch duct is opened again.

4. A filter as claimed in claim 3, whereiri the drainage duct upstream of the junction with the filtrate branch duct is provided with a fourth leading edge which co-operates, in the same way as a slide valve, with the first valve body, and wherein the four mentioned leading edges of the drainage duct are so disposed three-dimensionally and are so adapted to the first valve body and to the second valve body that, initially when the filter insert has been removed, only the drainage duct downstream of the junction with the filtrate branch duct is opened and the filtrate branch duct is closed, then the drainage duct upstream of the junction with the filtrate branch duct is also opened, and finally the filtrate branch duct itself is also opened again.

5. A filter as claimed in any of claims 2 to 4, wherein the valve spring of the by-pass valve is in the form of a compression spring and urges the second valve body against the first valve body and urges the first valve body against the incorporated filter insert.

6. A filter as claimed in any of claims 2 to 5, the drainage duct including the first valve seat for the axially sealing abutment of the first valve body, wherein the first valve body has, at its end facing the filter insert, a sleeve which is axially slidable between stop members and is pressed against the incorporated filter insert by a return spring which has greater axial force than the valve spring between the second valve body and a shoulder portion in the drainage duct, and said return spring is supported on the first valve body.

7. A filter substantially as herein described with reference to and as illustrated in the accompanying drawings.