Patent Description:
Typically, a filter device for filtering engine oil provides continuous cleaning to the engine oil. The filter device removes particulates such as carbon, soot and metals for example. Filters often comprise at least one highly efficient filtration medium which allows for removal of very fine particulates within the engine oil by passing the oil through the filtration medium. For modern vehicles there is an increasing need to remove smaller particles from the oil by increasing the efficiency of the filtration medium.

When an engine is running at standard or high temperatures, the viscosity of the oil is of a low enough level that the pressure drop across the filtration medium remains within acceptable limits. However, engine oil has increased viscosity at lower temperatures, for example when starting an engine from cold. This high viscosity means a large force is required to push the liquid through the filtration medium and particularly highly efficient filtration medium, resulting in a high pressure drop across the filtration medium. The oil pump must therefore increase the force it exerts to drive the oil through the filtration medium at colder temperatures. If the pressure drop across the filtration medium is too high, the flow of oil through the engine may be impeded risking engine damage. Damage may also be caused to the filtration medium.

It is known to provide a filtration medium with holes dispersed throughout the body of the filtration medium, as described on patent applications <CIT> or <CIT>. However, this has the drawback that the edge of the hole in the filtration medium can be rough which can allow for parts of the filtration medium to dislodge and contaminate the oil, further risking engine damage.

It is an aim of certain examples of the present invention to solve, mitigate or obviate, at least partly, at least one of the problems and/or disadvantages associated with the prior art.

The present invention provides a filter device as claimed in the appended claims.

According to an aspect, there is provided a filter device comprising: a housing; a first filtration medium within the housing such that for a liquid passing through the housing at least a portion is filtered by the first filtration medium; and a bypass for allowing a portion of the liquid to bypass the first filtration medium.

The filter device may comprise a frame supporting at least a portion of a periphery of the first filtration medium. The frame may comprise at least one aperture extending therethrough, e.g. such that a portion of the liquid can pass through the at least one aperture and bypass the first filtration medium.

According to another aspect of the invention, there is provided a filter device comprising: a housing; a first filtration medium within the housing such that for a liquid passing through the housing at least a portion is filtered by the first filtration medium; and a frame supporting at least a portion of a periphery of the first filtration medium; wherein the frame comprises at least one aperture extending therethrough, such that a portion of the liquid can pass through the at least one aperture and bypass the first filtration medium.

The filter device may further comprise a second filtration medium within the housing, such that at least the portion of the liquid which bypasses the first filtration medium passes through the second filtration medium.

Preferentially, the first filtration medium has a first filtration efficiency and the second filtration medium has a second filtration efficiency, which may be lower than the first filtration efficiency.

The housing may comprise a liquid inlet on a first side of the first filtration medium and a liquid outlet on a second side of the first filtration medium and the second filtration medium may be positioned between the inlet or outlet and the first filtration medium.

The second filtration medium may be positioned across or within the at least one aperture.

The frame may comprise at least a first frame portion and a second frame portion coupled together, and the aperture may be a pathway between the first frame portion and the second frame portion.

The aperture may comprise a sinuous pathway.

The frame may comprise a plurality of apertures.

The frame may comprise a liquid impermeable material.

The frame may be integral to or forms part of the housing.

The housing may comprise first and second housing portions which when coupled together form the frame and the aperture therethrough.

The first filtration medium may comprise at least one aperture extending therethrough, e.g. such that a portion of the liquid can pass through the at least one aperture and bypass the first filtration medium.

According to another aspect, there is provided a filter device comprising: a housing, a first filtration medium within the housing such that for a liquid passing through the housing at least a portion is filtered by the first filtration medium; and wherein the first filtration medium comprises at least one aperture extending therethrough, such that a portion of the liquid can pass through the at least one aperture and bypass the first filtration medium. According to an implementation of the invention, such a filter device may not comprise any frame around the first filtration medium.

At least one aperture may be formed by or obtained thanks to ultrasonic wave cutting or formed by or thanks to cold stamping. Therefore, a clean cut can be obtained.

The filter device may further comprise: a second filtration medium within the housing and at least a spacer between the first filtration medium and the second filtration medium. According to an implementation of the invention, such a filter device may not comprise any frame around the second filtration medium. According to an implementation of the invention, such the spacer may be a plastic insert between the first filtration medium and the second filtration medium.

The spacer may be molded for instance by plastic molding.

The first filtration medium and the second filtration medium may be joined or connected at their peripheries. The spacer may maintain a space (or a gap) between the first filtration medium and the second filtration medium. The joined or connected filtration medium may therefore form a bag.

The first and second filtration mediums may be joined or connected at their periphery by welding (eg by ultrasonic welding).

The filter device may further comprise a second filtration medium, which may be a low efficiency filtration medium. Preferentially said second filtration medium is protecting the first filtration medium.

The filter may further comprise: a third filtration medium within the housing comprising a frame and at least one filtration medium attached to the frame.

Preferentially, the frame further comprises at least one lug, said at least one lug at least partially obturating said at least one aperture.

The frame may be made of plastic and/or may be overmolded.

Examples of the invention are further described hereinafter with reference to the accompanying drawings, in which:.

Throughout the detailed description like numerals refer to like parts.

<FIG> illustrates a plan view of example of a filter device <NUM>. The filter device <NUM> includes a housing <NUM> for containing a liquid. The liquid may be engine oil for example. The housing <NUM> may have an inlet <NUM> and an outlet <NUM>. In some cases, the housing <NUM> may have multiple inlets <NUM> and/or outlets <NUM>. The inlet <NUM> allows liquid entry into the housing <NUM> and the outlet allows liquid to exit the housing <NUM>, this may be valve controlled or passive, for example. In some examples the liquid may be driven into and out of the housing <NUM> by a pump apparatus (not shown).

The housing <NUM> is partitioned by a filtration medium <NUM>. That is the filtration medium <NUM> divides the housing <NUM> such that liquid is directed therethrough for filtering. The filtration medium <NUM> is configured to remove particulates from the liquid when the liquid passes therethrough. For example, the filtration medium <NUM> may partition the housing <NUM> such that the filtration medium is between the inlet <NUM> and the outlet <NUM>. In this way a liquid enters the housing <NUM> via the inlet <NUM> and must pass through the filtration medium <NUM> to exit the housing via the outlet <NUM>.

Examples of suitable filtration media include but are not limited to a glass fibre or plastic fibre impregnated with resin. Suitably, this may be provided as a woven or non-woven fabric. The filtration medium <NUM> may be a single sheet of material or a plurality of stacked sheets for example. Moreover, in some examples the filtration medium <NUM> may be gathered or bunched etc to create a stacked arrangement of the filtration medium <NUM>. A further option is that the filtration medium could be pleated, as well as or instead of being stacked.

The filtration medium <NUM> is at least partially supported by a frame <NUM>. The frame <NUM> supports at least part of a periphery <NUM> of the filtration medium <NUM>. <FIG> illustrate examples of the frame <NUM> supporting the periphery <NUM> of the filtration medium <NUM>. The frame <NUM> may support the filtration medium <NUM> such that the filtration medium <NUM> extends wholly across the housing <NUM> (other than the frame <NUM> itself).

To support the periphery of the filtration medium <NUM>, the edge portion of the filtration medium is attached to the frame <NUM> such that the filtration medium <NUM> is held by the frame <NUM>. For example, the frame <NUM> may sandwich the periphery <NUM> of the filtration medium <NUM> between two frame portions, or a suitable adhesive may be used, or any other technique known to the person skilled in the art of designing filters. In some examples the frame <NUM> extends around the whole periphery <NUM> of the filtration medium <NUM>. The frame <NUM> may be minimised in projection from the housing so as to reduce the liquid-non permeable area taken up in the filter device <NUM>.

The frame <NUM> may be formed of a liquid impermeable material for example plastic (as may be the housing <NUM>). The frame <NUM> may be a substantially rigid structure so as to provide increased support to the filtration medium <NUM>. The frame <NUM> may form a connecting portion between the periphery <NUM> of the filtration medium <NUM> and the housing <NUM>. That is to the extent that the filtration medium <NUM> partitions the housing <NUM> the frame provides the interface between the housing <NUM> and the filtration medium <NUM>.

The frame <NUM> may be a separate component to the housing <NUM>. In some examples the frame <NUM> and the housing <NUM> may be integral or otherwise coupled together. For example, the housing <NUM> may include a protrusion (see <FIG>) which extends to support the periphery <NUM> of the filtration medium <NUM> in the same manner as the frame <NUM>. Where the frame <NUM> is part of the housing <NUM> it is only separately identified in order to explain how it includes apertures, as discussed below.

The frame <NUM> includes at least one aperture <NUM>. The aperture <NUM> extends through the frame <NUM> such that liquid can pass through the frame <NUM>. In the example of <FIG> the frame <NUM> includes two apertures <NUM>. It will be understood that the frame <NUM> can include one or more apertures <NUM> and the number of apertures may be dependent on the final engine use and/or liquid type for example. <FIG> for example illustrates a frame with six apertures <NUM>. The apertures <NUM> may be evenly spaced about the frame <NUM>. Further the apertures may be identical such that the flow through each aperture is constant. Alternatively, the apertures <NUM> may be sized or shaped differently for example in cases where the inlet <NUM> is positioned closer to one aperture <NUM> than another, and/or be irregularly distributed about the frame <NUM>.

The apertures <NUM> provide an alternative pathway for liquid flowing in the housing <NUM>. In this way a portion of the liquid which is flowing through the housing <NUM> is able to bypass the filtration medium <NUM> by passing through one of the apertures <NUM>. This reduces the pressure drop across the filtration medium <NUM>, particularly at lower temperatures. Furthermore, as the liquid cycles through the engine the portion of liquid bypassing the filtration medium <NUM> has a low likelihood of being the same portion each cycle. In this way the liquid is filtered by a filtration medium <NUM> with a high filtration efficiency while also reducing the pressure drop across the filtration medium <NUM>.

The filter device <NUM> may include additional filtration medium <NUM>, shown for example in <FIG> shows an example of a filter device <NUM> which includes a second filtration medium <NUM> partitioning the housing. The second filtration medium <NUM> has a lower filtration efficiency than the first filtration medium <NUM> described with reference to <FIG>. In this way, the second filtration medium <NUM> does not require a bypass because the pressure drop across the second filtration medium <NUM> is reduced by the reduction in efficiency. Of course, a second filtration medium <NUM> with the same efficiency as the first filtration medium may also be used with an aperture acting as a second bypass.

In the example shown in <FIG> the second filtration medium is positioned between the first filtration medium <NUM> and the outlet <NUM>. In this way, the liquid is filtered first by the first filtration medium <NUM> with a high filtration efficiency, then the liquid is filtered by the second filtration medium <NUM> with the lower efficiency. However, the second filtration medium <NUM> does not have a frame <NUM> with an aperture <NUM>, and thus has no bypass for the liquid. In this way, the liquid which bypasses the first filtration medium <NUM> is filtered by the second filtration medium <NUM>. Alternatively, or in addition the filter device <NUM> may have a second filtration medium <NUM> between the inlet <NUM> and the first filtration medium <NUM> such that all the liquid is filtered through a filtration medium <NUM> of lower filtration efficiency before being filtered by the higher filtration efficiency filtration medium <NUM> which includes the bypass.

In some (not shown) examples the apertures <NUM> may have a second filtration medium <NUM> across or within them. The second filtration medium <NUM> may have a lower filtration efficiency than the first filtration medium <NUM>. In this way, the liquid bypassing the first filtration medium <NUM> is filtered by the second filtration medium <NUM> in the aperture <NUM>.

<FIG> also illustrates an example aperture <NUM> with a sinuous path. For example, the aperture <NUM> may have a z-shaped cross section. In other words, the pathway through the frame <NUM> may not be direct. This causes the liquid to change direction when flowing through the aperture <NUM>. The change in direction in some examples causes contaminating particles to continue into the first filtration medium rather than bypass the first filtration medium. In examples of a filter device <NUM> with apertures <NUM> having sinuous pathways, the pathways may be identical for each aperture <NUM> or may alter in size and shape.

<FIG> illustrate a filter device <NUM> in which the frame <NUM> and housing <NUM> are integral. The frame <NUM> of <FIG> includes a first portion 110a and a second portion 110b which are coupled together. This coupling provides a pathway therebetween which is the aperture <NUM>.

<FIG> also illustrate the flow velocity of the liquid. The darker areas (red and orange) illustrating areas of lower speed and the lighter areas (blues and greens) are relatively high velocity areas. As can be seen, the liquid flows through the aperture <NUM> at a higher speed compared with the liquid passing though the filtration medium <NUM>.

To further illustrate the advantageous effects of the filter device <FIG> illustrates the pressure drop across a filtration medium with and without an aperture acting as a bypass for the filtration medium at varying flow rates when the oil temperature is <NUM>. As shown in the graph, the pressure drop across the filtration medium is higher when a bypass is not present. <FIG> illustrates the same configuration as <FIG> but at a lower temperature of <NUM>. The pressure drop with increasing flow rate is higher at the lower temperature. In addition the difference in pressure drop with and without a bypass is larger at lower temperatures.

<FIG> illustrates the percentage of the oil which is filtered by a filter device at different flow rates. The filter device has a frame including an aperture according to the present invention. Each line indicates a different oil temperature. As can be seen, as the temperature increases the amount of liquid filtered increases. Thus, the presence of a bypass reduces in effect as the temperature increases toward normal working temperature. In this sense, the bypass has the required effect at the lower temperatures (the cold starting temperature) of reducing the pressure drop across the filtration medium, without reducing the overall filtration during normal use (at higher temperatures).

Although illustrated throughout the application as a square housing portioned by a sheet of filtration medium, other iterations of the filter device may include housings of alternate shapes, for example a circular housing.

<FIG> illustrates a plan view of another example of a filter device <NUM> according to the invention. The filter device <NUM> includes a housing <NUM> for containing a liquid. The liquid may be engine oil for example. The housing <NUM> may have an inlet <NUM> and an outlet <NUM>. In some cases, the housing <NUM> may have multiple inlets <NUM> and/or outlets <NUM>. The inlet <NUM> allows liquid entry into the housing <NUM> and the outlet allows liquid to exit the housing <NUM>, this may be valve controlled or passive, for example. In some examples the liquid may be driven into and out of the housing <NUM> by a pump apparatus (not shown).

The housing <NUM> is partitioned by a first filtration medium <NUM>. Such first filtration medium <NUM> comprises an aperture <NUM> extending therethrough, such that a portion of the liquid can pass through the aperture <NUM> and bypass the first filtration medium <NUM>. The other portion of the liquid is directed through the first filtration medium <NUM> for filtering.

According to an aspect of the invention, the aperture <NUM> is obtained thanks to ultrasonic wave cutting. Of course, alternatively, the aperture <NUM> can also be obtained or cut thanks to cold stamping. Of course, the first filtration medium can comprise several apertures.

For instance, the first filtration medium is a felt. It may also be a screen or any other type of filtration medium.

The housing <NUM> further comprises a second filtration medium <NUM> which divides the housing <NUM> such that liquid is directed therethrough for filtering. For instance, the second filtration medium is a screen. It may also be a felt or any other type of filtration medium. The second filtration medium may also comprise at least one aperture, for example at least one bypass aperture.

The filter device may further comprise a spacer (for instance a plastic insert) positioned between the first filtration medium and the second filtration medium.

According to an aspect of the invention, the housing <NUM> is made of two separate shells or portions <NUM>, <NUM> which are joined or connected together at their peripheries <NUM>, <NUM> for instance thanks to a welding step or thanks to any other fastening mean (glue, screws, clip,. As an example, the two shells <NUM>, <NUM> and at least one of the first filtration medium <NUM> and the second filtration medium <NUM> may be joined altogether at their peripheries.

According to another example not illustrated on <FIG>, the filter device does not comprise the second filtration medium <NUM> and the spacer <NUM>. For example, in that case, the first filtration medium <NUM> may partition the housing <NUM> such that the filtration medium is between the inlet <NUM> and the outlet <NUM>. In this way a liquid enters the housing <NUM> via the inlet <NUM> and must pass through the filtration medium <NUM> or its aperture <NUM> to exit the housing via the outlet <NUM>.

According to an aspect of the invention, the second filtration medium <NUM> is configured to remove particulates from the liquid when the liquid passes therethrough.

Examples of suitable filtration media include but are not limited to a glass fibre or plastic fibre impregnated with resin or any other fibre, plastic or metallic net. Suitably, this may be provided as a woven or non-woven fabric. Each of the first filtration medium <NUM> and the second filtration medium may be a single sheet of material or a plurality of stacked sheets for example. Moreover, in some examples the filtration medium <NUM>, <NUM> may be gathered or bunched etc to create a stacked arrangement of the filtration medium <NUM>, <NUM>. A further option is that the filtration medium could be pleated, as well as or instead of being stacked.

According to an aspect of the invention, the first filtration medium and the second filtration medium are joined at their peripheries and wherein the spacer maintains a space between the first filtration medium and the second filtration medium. The joined or connected filtration medium may therefore form a bag.

According to an aspect of the invention, the first and second filtration mediums are joined or connected at their periphery by welding (eg by ultrasonic welding).

The housing <NUM> is partitioned by a first filtration medium <NUM>. Such first filtration medium <NUM> comprises apertures <NUM> extending therethrough, such that a portion of the liquid can pass through the apertures <NUM> and bypass the first filtration medium <NUM>. The other portion of the liquid is directed through the first filtration medium <NUM> for filtering.

According to an aspect of the invention, the apertures <NUM> are obtained thanks to ultrasonic wave cutting. Of course, alternatively, the aperture <NUM> can also be obtained or cut thanks to cold stamping. Of course, the first filtration medium can comprise one or several apertures.

For instance, the first filtration medium is a felt. It may also be a screen or any other type of filtration medium. Preferentially, the first filtration medium is a high efficiency filtration medium. Preferentially, high efficiency in the context of the present invention is to be understood as meaning an efficiency above <NUM>% for particle size of <NUM>.

Preferentially, the apertures <NUM> are bypass holes.

The housing <NUM> further comprises a second filtration medium <NUM> which divides the housing <NUM> such that liquid is directed therethrough for filtering. For instance, the second filtration medium is a screen. It may also be a felt or any other type of filtration medium. The second filtration medium may also comprise at least one aperture, for example at least one bypass aperture. Preferentially, the second filtration medium <NUM> is a low efficiency filtration medium. Preferentially, low efficiency in the context of the present invention is to be understood as meaning an efficiency below <NUM>% for particle size of <NUM>.

Preferentially, the second filtration medium <NUM> is implemented to protect the first filtration medium <NUM>. Preferentially, the second filtration medium can be used to prevent or slow down the clogging of the first filtration medium <NUM>.

Preferentially, the housing <NUM> further comprises a third filtration medium <NUM> which is illustrated by <FIG>.

For instance, the third filtration medium <NUM> comprises a frame <NUM> to which is/are attached at least one filtration medium <NUM>. In the example of <FIG>, four filtration medium <NUM> which are for instance four plastic screens (of course it can also be metallic screens) are attached to the frame <NUM>. The frame <NUM> for instance comprises four legs <NUM>. Preferentially, the frame comprises one or several lugs <NUM>. Preferentially, said one or several lug(s) is(are) at least partially obturating said at least one aperture(s).

Preferentially, the frame <NUM> is made of plastic and is overmolded. For instance, the frame is made of PA6 or PA66 plastic. Preferentially, the frame <NUM> has a role of spacer or is a spacer within the housing.

Preferentially, at least one of the lugs <NUM> is penetrating an (or several) aperture(s) <NUM> (hereafter "corresponding aperture(s)") of the first filtration medium. Preferentially, said at least one of the lugs <NUM> is partially or totally obturating the corresponding aperture(s) <NUM>. Preferentially, the frame is provided with a quantity of lugs <NUM> such that each of the apertures <NUM> is partially or totally obturated by a lug <NUM> except one or several aperture(s) <NUM> which is(are) not obturated by a lug.

According to an aspect of the invention, the housing <NUM> is made of two separate shells or portions <NUM>, <NUM> which are joined or connected together at their peripheries <NUM>, <NUM> for instance thanks to a welding step or thanks to any other fastening mean (glue, screws, clip,. Preferentially, the third filtration medium <NUM> is welded to the top shell or portion <NUM> thanks to a laser before the two shells or portions are joined or connected together.

As an example, the two shells <NUM>, <NUM> and at least one of the first filtration medium <NUM> and the second filtration medium <NUM> may be joined altogether at their peripheries.

According to another example not illustrated on <FIG>, the filter device does not comprise the second filtration medium <NUM>.

Examples of suitable filtration media include but are not limited to a glass fibre or plastic fibre impregnated with resin or any other fibre, plastic or metallic net. Suitably, this may be provided as a woven or non-woven fabric. Each of the first filtration medium <NUM> and the second filtration medium <NUM> may be a single sheet of material or a plurality of stacked sheets for example. Moreover, in some examples the filtration medium <NUM>, <NUM> may be gathered or bunched etc to create a stacked arrangement of the filtration medium <NUM>, <NUM>. A further option is that the filtration medium could be pleated, as well as or instead of being stacked.

According to an aspect of the invention, the first filtration medium and the second filtration medium are joined at their peripheries and wherein the third filtration medium or spacer maintains a space between the first filtration medium and the second filtration medium. The joined or connected filtration medium may therefore form a bag.

Claim 1:
A filter device (<NUM>; <NUM>; <NUM>) comprising:
a housing (<NUM>; <NUM>; <NUM>);
a first filtration medium (<NUM>; <NUM>; <NUM>) within the housing such that for a liquid passing through the housing at least a portion is filtered by the first filtration medium; and
a bypass (<NUM>; <NUM>; <NUM>) for allowing a portion of the liquid to bypass the first filtration medium;
wherein the first filtration medium (<NUM>; <NUM>) comprises at least one aperture (<NUM>; <NUM>) extending therethrough, such that a portion of the liquid can pass through the at least one aperture and bypass the first filtration medium;
wherein the filter device further comprises a second filtration medium (<NUM>; <NUM>) which is a low efficiency filtration medium;
characterized in that
the filter further comprises a third filtration medium (<NUM>) within the housing comprising a frame (<NUM>) and at least one filtration medium attached to the frame;
wherein the frame further comprises at least one lug (<NUM>), said at least one lug at least partially obturating said at least one aperture.