Patent Description:
This disclosure relates to air filtration. In particular, this disclosure relates to precleaner assemblies for air cleaners, which provide for a precleaning to remove dust or other material from the air prior to the air being passed through filter media within an air cleaner.

Gas streams often carry material entrained (for example dust or moisture) therein. In many instances, it is desirable to remove some or all of the entrained material from a gas flow stream. For example, air intake streams to engines for motorized vehicles, construction equipment or for power generation equipment, often include moisture or particulate material therein. The particulate material, should it reach the internal workings of the various mechanisms involved, can cause substantial damage thereto. The moisture can also damage equipment. It is therefore preferred, for such systems, to reduce the level of particulate and moisture in the gas flow upstream of the engine or other equipment involved. A variety of air filter arrangements have been developed for such removal. In general, however, continued improvements are sought. Document <CIT> discloses an existing precleaner arrangement for separating a portion of the entrained material from air flow entering an engine air cleaner.

A precleaner arrangement is provided which improves the prior art. The precleaner arrangement of the invention is recited in the appended set of claims.

The precleaner arrangement of the present invention is provided for separating a portion of entrained material from air flow air entering an engine air cleaner. The precleaner arrangement includes a precleaner housing and at least a first flexible air deflection vane with a fixed portion secured to the precleaner housing and a deflectable portion. The deflectable portion includes a curved section extending from the fixed portion and a tail section extending from the curved section.

The fixed portion of the first air deflection vane can define an upper terminal edge (i. e, leading edge). The deflectable portion of the first air deflection vane can define a perimeter including an inner side edge and outer side edge and a lower terminal edge bridging the inner and outer side edges. Each of the inner and outer side edges extends from the fixed portion. The tail section defines the lower terminal edge (i.e., trailing edge).

The curved section has a center of curvature along the inner side edge and a center of curvature along the outer side edge. The center of curvature along the inner side edge is spaced from the upper terminal edge a greater axial distance than the center of curvature along the outer side edge is spaced from the upper terminal edge.

In example embodiments, the precleaner housing has a central hub with a central longitudinal axis passing therethrough. The lower terminal edge is angled at a non-zero and non-perpendicular angle relative to a plane orthogonal to the central longitudinal axis.

In example embodiments, the tail section defines an inner corner at an intersection of the inner side edge and the lower terminal edge, and an outer corner at an intersection of the outer side edge and the lower terminal edge. The outer corner is axially spaced closer to the upper terminal edge than the inner corner is from the upper terminal edge.

In one or more embodiments, the tail section defines an inner corner at an intersection of the inner side edge and the lower terminal edge, and an outer corner at an intersection of the outer side edge and the lower terminal edge. The outer corner is angled from a plane orthogonal to the central longitudinal axis at a first non-zero angle; and the inner corner is angled from a plane orthogonal to the central longitudinal axis at a second non-zero angle.

In some embodiments, the first angle and the second angle are equal.

In some embodiments, the second angle is not greater than the first angle.

In some embodiments, the first angle and second angle range between <NUM>° and <NUM>°.

In some embodiments, the first angle is greater the second angle.

Some implementations include the tail section having a radial thickness greater at the inner side edge and decreasing in thickness to the outer side edge.

Some embodiments include the thickness at the inner side edge being up to ten times the thickness of the outer side edge.

In some arrangements, the precleaner housing has a central hub; and the at least first flexible air deflection vane includes a plurality of flexible air deflection vanes positioned around the central hub, each with a fixed portion secured to the precleaner housing and a deflectable portion. The deflectable portion of each vane includes a curved section extending from the fixed portion and a tail section extending from the curved section. The deflectable portion of each vane is configured to deflect in response to a sufficient air flow rate increase through the precleaner arrangement, in use.

In some arrangements, the precleaner housing further includes an outer ring, and each of the flexible air deflection vanes is positioned between the outer ring and the central hub. Each flexible air deflection vane is secured to the central hub and outer ring at the fixed portion of each vane.

In some embodiments, there are at least six flexible air deflection vanes.

In some arrangements, there are at least ten flexible air deflection vanes.

In one or more embodiments, the tail section of each flexible air deflection vane has a variable thickness in a radial direction. A largest thickness being along the central hub and lessoning to a portion of the vane next to the outer ring.

In some implementations, the plurality of flexible air deflection vanes circumferentially overlap.

In some implementations, the circumferential overlap of the vanes is no greater than <NUM>°, as measured from the central hub.

In many examples, each of the fixed portions of the flexible air deflection vanes defines an upper terminal edge, and each of the deflectable portions of the air deflection vanes defines a perimeter. The perimeter includes an inner side edge and an outer side edge and a lower terminal edge bridging the inner and outer side edges. Each of the inner and outer side edges extend from the fixed portion. The tail section defines the lower terminal edge.

Many arrangements include an inner radial gap defined between each of the inner side edges and the central hub, and an outer radial gap defined between each of the outer side edges and the outer ring.

In some embodiments, each of the flexible air deflection vanes has a width extending between the inner side edge and the outer side edge. The inner radial gap has a width that is no more than <NUM>% of the width of each vane. The outer radial gap has a width that is no more than <NUM>% of the width of each vane.

In many implementations, the at least first flexible air deflection vane comprises in the inlet vane system. The precleaner arrangement can further include an outlet vane system downstream of the inlet vane system. The outlet vane system may have a plurality of rigid vanes fixed to the precleaner arrangement.

The inlet vane system may induce a vortical air flow in one of a clockwise or counterclockwise direction, while the outlet vane system will reverse the vortical air flow of the inlet vane system.

The deflectable portion can be configured to deflect in response to a sufficient air flow rate change through the precleaner arrangement, in use.

In another aspect, a precleaner arrangement for separating a portion of entrained material from air flow air entering an engine air cleaner is provided. The precleaner arrangement includes a precleaner housing; an inlet vane component; and an outlet vane system. The inlet vane system is in the precleaner housing and is arranged to induce a vortical air flow in one a clockwise or counterclockwise direction. The outlet vane system is arranged to reverse the vortical air flow of the inlet vane system.

In some embodiments, the inlet vane system comprises a plurality of flexible air deflection vanes, each having a fixed portion secured to the precleaner housing and a deflectable portion. The deflectable portion includes a curved section extending from the fixed portion and a tail section extending from the curved section. The deflectable portion is configured to deflect in response to a sufficient air flow rate increase through the precleaner arrangement, in use.

In some implementations, the precleaner housing has a central hub and the plurality of flexible air deflection vanes are secured to and positioned around the central hub.

In some example embodiments, the outlet vane system comprises a plurality of rigid vanes secured to and positioned around the central hub.

Methods of precleaning air are provided and include providing and directing air flow through arrangements as characterized above.

Examples of dimensions, configurations, and materials are provided to indicate various ways in which principles of this disclosure can be implemented.

<FIG> depicts a schematic view of an air cleaner assembly <NUM> of the type typically used for filtering engine intake air for internal combustion engines. The air cleaner assembly <NUM> can include a main air cleaner <NUM>. Upstream of the main air cleaner <NUM> is a precleaner arrangement <NUM>. In alternative systems, the precleaner arrangement <NUM> can operate as the sole air cleaner, and no main air cleaner is needed downstream.

The main air cleaner <NUM> typically will have a serviceable air filter or air filter element, which can be removed and replaced.

In typical operation, air enters the air cleaner assembly <NUM> by entrance into the precleaner arrangement <NUM> in the direction arrow <NUM>. The air exits the air cleaner <NUM> in the direction of arrow <NUM>, to be directed to an engine intake manifold, or other equipment structure.

The precleaner arrangement <NUM> allows for separation of a portion of dust or other material entrained within air to be cleaned, prior to the air passing through the air filter element within the main air cleaner <NUM>. The precleaner arrangement <NUM> generally operates by imparting a circular, vortical or coiled momentum to the incoming air including the entrained material, as opposed to passage of the air through a filter media. This vortical or coiled momentum causes a deposition or separation of a portion of the entrained material from the air flow, before the air is transferred into the main air cleaner <NUM>, which includes the filter element.

Precleaners generally provide restriction to air flow. The reason for this is that the vanes (sometimes referred to as blades or fins) which divert the air into a circular or vortical pattern generally need to be positioned an extension across the direction of inlet air flow <NUM> to impart the desired tangential momentum to the flow. This causes restriction. The precleaner arrangement <NUM> of the present disclosure is helpful in reducing restriction that is typical of many types of prior art precleaners.

One example embodiment of precleaner arrangement <NUM> is shown in <FIG>. In general, the precleaner arrangement <NUM> has an inlet vane assembly <NUM> with vanes that flex under the load applied by the fluid (incoming air) on the vane surface. The inlet vane assembly <NUM> is designed to a low flow condition and passably flexes as flow rate increases to a higher flow condition, resulting in a lower pressure drop than a fixed vane would and maintaining particle separation performance in a pre-specified, e.g. about <NUM>:<NUM> , turn down ratio situation. While the inlet vane assembly <NUM> can be used alone or independently with the main air cleaner <NUM>, many preferred embodiments will additionally include an outlet vane assembly <NUM> to help with efficiency and pressure drop.

The precleaner arrangement <NUM> includes precleaner housing <NUM>. An exterior of the precleaner housing <NUM> is shown at <NUM> in <FIG>, while interior components <NUM> are shown in <FIG>. The exterior <NUM> of the housing <NUM> contains within it the inlet vane assembly <NUM>. Embodiments that also include the outlet vane assembly <NUM> will also have the outlet vane assembly <NUM> in an interior portion of the housing <NUM>.

In this embodiment, the housing <NUM> has a central hub <NUM> and an outer skirt or ring <NUM>. The outer ring <NUM> surrounds or circumscribes the hub <NUM>.

There is at least a first flexible air deflection vane <NUM> secured to the precleaner housing <NUM>.

In reference now to <FIG> and <FIG>, the first flexible air deflection vane <NUM> has a fixed portion <NUM> and a deflectable portion <NUM>. The fixed portion <NUM> is secured to the housing <NUM>. While many different embodiments are possible, in the one shown, the vane <NUM> is positioned between the outer ring <NUM> and the central hub <NUM>. The fixed portion <NUM> can be secured to the hub <NUM> and the outer ring <NUM>. <FIG> shows the inlet vane assembly <NUM> having a plurality of flexible air deflection vanes <NUM> positioned around the central hub <NUM>, each having the fixed portion <NUM> cured to the precleaner housing <NUM>. In <FIG>, the air deflection vanes <NUM> are shown in a resting state, with little or no air flow passing therethrough.

Attention is directed to <FIG> and <FIG>, which show enlarged views of one air deflection vane <NUM>. The fixed portion <NUM> of the vane <NUM> defines an upper terminal edge <NUM>. The deflectable portion <NUM> extends from the fixed portion <NUM>.

The fixed portion <NUM>, in this embodiment, includes opposite leading edges <NUM>, <NUM>. The leading edges <NUM>, <NUM> are illustrated as generally being straight. The upper terminal edge <NUM> extends between and bridges the two leading edges <NUM>, <NUM>.

The deflectable portion <NUM> includes a curved section <NUM>. The curved section <NUM> extends from the fixed portion <NUM>.

The deflectable portion <NUM> further includes a tail section <NUM>. The tail section <NUM> extends from the curved section <NUM>.

The deflectable portion <NUM> is configured to deflect in response to a sufficient air flow rate increase through the precleaner arrangement <NUM>, in use. In many preferred embodiments, the vane <NUM> is made of a material so that the deflectable portion <NUM> has a first orientation and a second orientation. The deflectable portion <NUM> will have a memory bias toward the first orientation. This first orientation is shown generally in <FIG>. The second orientation is shown in phantom lines at <FIG>. In the second orientation, the vanes <NUM> are deflected along arrow <NUM> from the orientation of <FIG>, which allows less air flow to flow through, to the more open orientation, in which there is more open air space between adjacent vanes <NUM>, and which allows more air flow, decreasing the restriction.

Still in reference to <FIG> and <FIG>, in this example embodiment, the deflectable portion <NUM> defines a perimeter <NUM>. The perimeter <NUM> includes an inner side edge <NUM>, which is oriented adjacent to the hub <NUM>, and an opposite outer side edge <NUM>, which is oriented adjacent to the outer ring <NUM>. The perimeter <NUM> further includes a lower terminal edge <NUM>. The lower terminal edge <NUM> extends or bridges the outer side edges <NUM>, <NUM>. The tail section <NUM> defines the lower terminal edge <NUM>.

In this embodiment, the lower terminal edge <NUM> is shown as straight. There can be many variations including parabolic, wavy, concave, convex, exponential, or others. The shape of the lower terminal edge <NUM> can be used to help tune restriction or efficiency.

The inner side edge <NUM> extends from the fixed portion <NUM>. In this example, the inner side edge <NUM> extends from the leading edge <NUM> of the fixed portion <NUM>.

The outer side edge <NUM> extends from the fixed portion <NUM>. In this example, the outer side edge <NUM> extends from the leading edge <NUM> of the fixed portion <NUM>.

As can be seen in <FIG>, the vane <NUM> has an upstream surface <NUM> and an opposite downstream surface <NUM>. The upstream surface <NUM> is the surface first encountered by the inlet air when passing through the inlet vane assembly <NUM>. The downstream surface <NUM> is the surface of the vane <NUM> that is opposite of the upstream surface <NUM>.

As mentioned previously, the deflectable portion <NUM> includes curved section <NUM>. The curved section <NUM> connects the leading edges <NUM>, <NUM> of the fixed portion <NUM> to the tail section <NUM>. In many arrangements, and in the example embodiment shown, the curved section <NUM> is designed to adjust for axial flex of the vane <NUM> and radial flex of the vane <NUM>. In particular, the curved section <NUM> helps with coarse tuning of radial deflection of the vane <NUM>.

The curved section <NUM> can have a radius of curvature along the inner side edge <NUM> which is spaced from the upper terminal edge <NUM> a different distance than the center of curvature is spaced from the upper terminal edge <NUM> along the outer side edge <NUM>. In many preferred embodiments, the center a curvature <NUM> along the inner side edge is spaced from the upper terminal edge <NUM> an axial distance further than the center of curvature <NUM> along the outer side edge is spaced from the upper terminal edge <NUM>. This helps to control and allow for axial flex of the vane <NUM> while tuning the radial flex.

Attention is directed to <FIG>, which is an enlarged view of a cross section shown in <FIG>. The lower terminal edge <NUM> is shown in cross-section. The lower terminal edge <NUM> is angled at a non-zero and non-perpendicular angle <NUM> relative to a plane orthogonal to a central longitudinal axis <NUM> (<FIG>) passing through the central hub <NUM>. A difference in height is shown at <NUM> in <FIG> along the lower terminal edge <NUM> from the inner side edge <NUM> to the outer side edge <NUM>. This height difference <NUM> is also referred to as the vane tilt <NUM>.

In reference again to <FIG>, by reviewing the drawing of the vane <NUM>, it can be appreciated that the tail section <NUM> defines an inner corner <NUM> at an intersection of the inner side edge <NUM> and the lower terminal edge <NUM>. The tail section <NUM> also defines an outer corner <NUM> at an intersection of the outer side edge <NUM> and the lower terminal edge <NUM>. In most preferred embodiments, the vane <NUM> will include the vane tilt <NUM> and result in the outer corner <NUM> being axially spaced closer to the upper terminal edge <NUM> than the inner corner <NUM> is spaced from the upper terminal edge <NUM>. The vane tilt <NUM> will be dependent upon the particular geometry, and in some embodiments, it can be no tilt such that the inner corner <NUM> and outer corner <NUM> are even with each other.

The precleaner arrangement <NUM> may also be designed to control the tangential velocity and vortex shape. One way of doing this is by adjusting the pitch of the vane <NUM>. Attention is directed to <FIG> and <FIG> illustrates the central longitudinal axis <NUM>. A plane orthogonal to the central longitudinal axis <NUM> defines a horizontal plane. In <FIG>, the outer corner <NUM> is angled from the plane orthogonal to the central longitudinal axis <NUM> at a first non-zero angle P1. The inner corner <NUM> is angled from the plane orthogonal to the central longitudinal axis <NUM> at a second non-zero angle P2. In many embodiments, the first angle P1 will be greater than the second angle P2. For example, the first angle P1 and second angle P2 can range between <NUM>° and <NUM>°. In some embodiments, the second angle P2 can be equal or about the same as the first angle P1. In most embodiments, the second angle P2 is no greater than equal to the first angle P1. Many embodiments are possible.

As mentioned previously, the positions of the vanes <NUM> can be adjusted to allow for axial flexing and minimizing radial flexing. The vane tilt <NUM> is used for coarse tuning of the radial deflection. For fine tuning of the radial deflection, the vanes <NUM> may have a variable thickness.

<FIG> shows a cross-section of one of the vanes <NUM>. In this embodiment, the tail section <NUM> has a radial thickness T1 which is greatest at the inner side edge <NUM> and decreases in thickness continuously to the outer side edge <NUM>. The thickness at the outer side edge <NUM> is shown at T2. Many embodiments are possible. The thickness T1 at the inner side edge <NUM> may be up to <NUM> times the thickness T2 at the outer side edge <NUM>. In some applications, the entire vane <NUM> has a non-uniform thickness.

As can be seen in <FIG>, the air deflection vanes <NUM> are positioned around the central hub <NUM>. Each of the vanes <NUM> has fixed portion <NUM> secured to the precleaner housing <NUM>. The deflectable portion <NUM> of each of the vanes <NUM> is free and unattached to the housing <NUM>.

In the embodiment shown in <FIG>, each of the vanes <NUM> is positioned between the outer ring <NUM> and the central hub <NUM>. In many examples, the vanes <NUM> are secured to the central hub <NUM> and the outer ring <NUM> at the fixed portion <NUM> of each vane <NUM>.

The vanes <NUM> can be secured to the housing <NUM> using a variety of techniques. For example, the vanes <NUM> can be secured to the hub <NUM> and outer ring <NUM> using molding. The molding can be in the form of a single shot mold or in the form of multi-stage injection molding. Other techniques can be used to secure the vanes <NUM> to the hub <NUM> and outer ring <NUM> including interference or snap-fitting, or by use of ultrasonic welding.

<FIG> shows a connection piece <NUM> which forms a part of the upper terminal edge <NUM> and is part of the fixed portion <NUM>. The connection piece <NUM> includes an inner side piece <NUM> adjacent to the hub <NUM> and an opposite outer side piece <NUM> adjacent to the outer ring <NUM>. The inner side piece <NUM> can be the only portion of the vane <NUM> that is secured to the hub <NUM>. A remaining portion of the vane <NUM> is free of connection to the hub <NUM>. Similarly, the outer side piece <NUM> can be the only portion of the vane <NUM> connected to the outer ring <NUM>, freeing the remaining portion of the vane <NUM> from any connection to the ring <NUM>. As can be appreciated from <FIG>, inner side piece <NUM> is joined by the curved section <NUM> and the inner side edge <NUM>. The outer side piece <NUM> is joined by the curved section <NUM> and the outer side edge <NUM>.

The number of vanes <NUM> will vary depending upon the inner radius of the outer ring <NUM> and the modulus of elasticity of the material of the vane <NUM>. In many cases, there are at least six flexible air deflection vanes <NUM>, and in many cases, there can be at least ten flexible air deflection vanes <NUM>. In many cases, there will be fewer than <NUM> air deflection vanes <NUM>.

The vanes <NUM> can be arranged around the hub <NUM> to have a circumferential overlap. The amount of overlap is selected to affect the overall separation efficiency. <FIG> is a bottom view of the inlet vane assembly <NUM>. The downstream surfaces <NUM> of the vanes <NUM> can be seen. Angle <NUM> in <FIG> illustrates the amount of circumferential overlap of two of the vanes <NUM>. In some cases, there may be no overlap, but rather, open air gaps between adjacent vanes <NUM>. In other cases, the overlap <NUM> can be no greater than <NUM>° as measured from the central hub <NUM>. In cases where there is separation between the vanes <NUM>, typically there will be about <NUM>° at angle <NUM>.

To allow the deflectable portion <NUM> of each of the vanes <NUM> to move and deflect, it is helpful to have an inner radial gap <NUM> between the inner side edge <NUM> and the hub <NUM> (see <FIG>). It is also helpful to have an outer radial gap <NUM> (<FIG>) between each of the outer side edges <NUM> and the outer ring <NUM>. The size of the gaps <NUM>, <NUM> is selected to allow for movement of the deflectable portions <NUM> of the vanes <NUM>, but small enough to minimize air bypass. In many instances, the inner and outer radial gaps, <NUM>, <NUM> are at a dimension (width) that no more than <NUM>% of the width of each vane <NUM>. The width of each vane <NUM> is the dimension extending between the inner side edge <NUM> and outer side edge <NUM>. In some cases, the width of the gaps <NUM>, <NUM> can be zero so that the edges <NUM>, <NUM> just barely touch the hub <NUM> and outer ring <NUM>.

<FIG> is a schematic view of two of the vanes <NUM>. <FIG> shows a helix trim angle at <NUM>. The helix trim angle <NUM> can be adjusted to tune the radial deflection of the vanes <NUM> and can be rotated in the positive or negative direction. A plane <NUM> is defined by the Z-axis (centerline) through the beginning of the pitch curve on the vane <NUM>. The Z axis, coming out of the paper, is illustrated at <NUM>, and it passes through the end point of the pitch curve.

The precleaner arrangement <NUM> can include a plurality of inlet vane assemblies <NUM>, arranged within the precleaner housing and in parallel to each other, as illustrated in <FIG>.

As mentioned previously, the precleaner arrangement <NUM> includes the inlet vane assembly <NUM> and may also include an optional outlet vane assembly <NUM>. In systems that include both an inlet vane assembly <NUM> and outlet vane assembly <NUM>, the use of the flexible vanes <NUM> in the inlet vane assembly <NUM> are optional. That is, the precleaner arrangement <NUM> can include inlet vane assembly <NUM> and outlet vane assembly <NUM>, wherein the inlet vane assembly <NUM> has standard, rigid vanes, and not vanes designed to have deflectable portions <NUM>.

The outlet vane assembly <NUM> can be provided based on the expected flow rate and pitch P1, P2 (<FIG>) of the inlet vanes <NUM> in order to recover pressure loss in the precleaner arrangement <NUM>, and the expected scavenge rate relative to the primary flow rate.

<FIG> show one example embodiment of the outlet vane assembly <NUM>. The outlet vane assembly <NUM> includes a plurality of fins or vanes <NUM> surrounding a central hub <NUM>. Surrounding each of the vanes <NUM> is an outer ring <NUM>. The ring <NUM> has a diameter <NUM> (<FIG>) that is chosen based upon the desired separation efficiency.

A height of each of the outlet vanes <NUM> is shown at <NUM> in <FIG>. The height <NUM> will be selected depending upon the method of scavenging and the attachment of the vanes <NUM> to the hub <NUM> and also helps with efficiency.

The outlet vane assembly <NUM> is placed downstream of the inlet vane assembly <NUM> at a desired baffle to baffle distance <NUM>. This distance <NUM> will be not greater than ten times the radius of the outer ring <NUM> of the inlet vane assembly <NUM>. The distance <NUM> will be at least the height <NUM> of the ring <NUM>.

The number of outlet vanes <NUM> can vary, and typically be dependent on the modulus of the vane <NUM> used and the radius of the ring <NUM>. For example, there can be at least three vanes <NUM>, for example at least five vanes <NUM>, and no greater than <NUM> vanes <NUM>. In the example shown in <FIG>, there are six vanes <NUM>.

The vanes <NUM> can be made to have a pitch, such as shown in <FIG>. There are two pitches shown in <FIG>, P3 and P4. The pitches P3, P4 will be dependent upon the pitches P1, P2 of the inlet vanes <NUM>. In the example shown, the pitches P3, and P4 are multiple times greater than the pitches P1 and P2. The thickness of the vanes <NUM> can range from <NUM>-<NUM>, for example, <NUM> to <NUM>.

The vanes <NUM> in the outlet vane assembly <NUM> are twisted to oppose the vortical air flow from the direction of air flow that is induced by the inlet vane assembly <NUM>. The inlet vane assembly <NUM> can be arranged to induce a vortical air flow in one of a clockwise or counter clockwise direction. The outlet vane system <NUM> is arranged to "de-swirl" or to reverse the direction of vortical air flow of the inlet vane assembly <NUM>. For example, if the inlet vane assembly <NUM> induces flow in a clockwise direction, when it encounters the vanes <NUM> of the outlet vane assembly <NUM>, the vanes <NUM> will work to straighten the air flow and de-swirl it by trying to cause the airflow to go in counter clockwise direction and result in a substantially straight flow.

It should be appreciated that the vanes <NUM> can be selected to have materials and dimensions that will have an effect on system performance. The deflectable portion <NUM> of the vanes <NUM> will be "deflectable. " "Deflectable", within this context, will be vanes having a modulus of elasticity as high as <NUM>,<NUM> MPa and typically at least <NUM> MPa. One useful material for the deflectable portion <NUM> of the vanes <NUM> is an injection molding grade resin made from Hytrel having a modulus of elasticity that is consistent over the range of temperature between -<NUM>° to <NUM>° C. Other materials are possible. Deflectable vanes <NUM>, within this context, will have a thickness typically no greater than <NUM> and at least <NUM>. The deflectable portion <NUM> is configured to deflect in response to a sufficient air flow rate change through the precleaner arrangement, in use, to affect the pressure drop and efficiency.

The diameter of the ring <NUM> can depend upon the modulus of elasticity of the vane <NUM>. The diameter of the hub <NUM> will be no greater than <NUM>% of the diameter of the ring <NUM> and at least <NUM>% of the diameter of the ring <NUM>.

The precleaner arrangement <NUM> can be designed to result in desired responses. For example, if it is desirable to affect the shape of the vortex and separation efficiency, the pitches P1, P2, P3, P4 of the vanes <NUM>, <NUM> can be modified. Other variables to affect vortex shape and separation efficiency include the inner and outer radial gaps <NUM>, <NUM>; the overlap angle <NUM>; the baffle to baffle distance <NUM>, and the scavenge ring diameter <NUM>.

To affect the pressure drop of the precleaner arrangement <NUM>, the following factors can be adjusted; the modulus of elasticity of the vanes <NUM>, <NUM>; the amount of vane deflection; the radius of the hub <NUM> and ring <NUM>; the vane pitches P1, P2, P3, P4; and the vane overlap <NUM>.

To affect the amount of vane deflection, the following variables can be adjusted: the modulus of elasticity; the vane thickness; the radius of the ring <NUM>; the number of vanes <NUM>; the overlap angle <NUM>; and the vane tilt <NUM>.

The precleaner arrangement <NUM> can be used in a method of precleaning air. The air to be filtered is directed into an air cleaner assembly <NUM> at arrow <NUM>. The inlet vane assembly <NUM> induces vortical air flow, which causes dust or other debris to inertially separate from a remaining portion of the air flow. The vortical air, without at last some of the dust or debris then flows either directly into the main air cleaner <NUM> or passes through an outlet vane assembly <NUM>.

If passing through an outlet vane assembly <NUM>, outlet vanes will reverse the vortical air flow induced by the inlet vane assembly <NUM> to substantially straighten or deswirl the air flow. The substantially straightened air flow is then directed to the main air cleaner.

Claim 1:
A precleaner arrangement (<NUM>) for separating a portion of entrained material from air flow air entering an engine air cleaner; the precleaner arrangement (<NUM>) comprising:
(a) a precleaner housing (<NUM>); and
(b) a plurality of air deflection vanes (<NUM>), each having a fixed portion (<NUM>) secured to the precleaner housing (<NUM>) and a deflectable portion (<NUM>); the fixed portion of the first air deflection vane (<NUM>) defines an upper terminal edge (<NUM>);
(i) the deflectable portion (<NUM>) including a curved section (<NUM>) extending from the fixed portion (<NUM>) and a tail section (<NUM>) extending from the curved section (<NUM>);
(ii) the deflectable portion including an inner side edge (<NUM>) and an outer side edge (<NUM>);
(iii) the curved section (<NUM>) has a center of curvature along the inner side edge (<NUM>) and a center of curvature along the outer side edge (<NUM>);
wherein the air deflection vanes (<NUM>) are arranged to induce a vortical air flow; and wherein the center of curvature along the inner side edge (<NUM>) is spaced from the upper terminal edge (<NUM>) a greater axial distance than the center of curvature along the outer side edge (<NUM>) is spaced from the upper terminal edge (<NUM>).