Patent Description:
Shock absorbing devices are used in a wide variety of vehicle suspension systems for controlling motion of the vehicle and its tires with respect to the ground and for reducing transmission of transient forces from the ground to the vehicle. Shock absorbing struts are a common component in most aircraft landing gear assemblies. Shock struts control motion of the landing gear, and absorb and damp loads imposed on the gear during landing, taxiing, braking, and takeoff.

A shock strut generally accomplishes these functions by compressing a fluid within a sealed chamber formed by hollow telescoping cylinders. The fluid generally includes both a gas and a liquid, such as hydraulic fluid or oil. One type of shock strut generally utilizes an "air-over-oil" arrangement wherein a trapped volume of gas is compressed as the shock strut is axially compressed, and a volume of oil is metered through an orifice. The gas acts as an energy storage device, similar to a spring, so that upon termination of a compressing force the shock strut returns to its original length. Shock struts also dissipate energy by passing the oil through the orifice so that as the shock absorber is compressed or extended, its rate of motion is limited by the damping action from the interaction of the orifice and the oil. <CIT> discloses an example of a shock strut.

Conventional orifice plates used in landing gear shock struts are made entirely of metallic components.

A solution is provided by a shock strut defined by claim <NUM> and a method for manufacturing a non-metallic orifice plate is provided as defined by claim <NUM>.

Th features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein without departing from the scope of the invention as defined by the claims.

As disclosed herein, a <NUM>% non-metallic orifice plate comprises a wear-resistant inner diameter surface, an outer diameter surface, a first side surface extending between the inner diameter surface and the outer diameter surface, and a second side surface extending between the inner diameter surface and the outer diameter surface, the second side surface disposed opposite the non-metallic orifice plate from the first side surface. The disclosed non-metallic orifice plate may provide weight-savings, while maintaining wear resistance at the inner diameter surface.

With reference to <FIG>, a section view of a shock strut <NUM> in a fully extended position is illustrated, in accordance with various embodiments. Shock strut <NUM> may be configured to absorb and dampen forces transmitted between a vehicle and the ground. Shock strut <NUM> may comprise a strut piston <NUM> and a strut cylinder <NUM>. Strut cylinder <NUM> may be configured to receive strut piston <NUM> in a manner that allows the two components to telescope together and absorb and dampen forces transmitted between a first end <NUM> (also referred to herein as a proximal end) and a second end <NUM> (also referred to herein as a distal end) of shock strut <NUM>. In various embodiments, a fluid, such as a hydraulic fluid, and oil, and/or a gas is located within strut cylinder <NUM>. Strut cylinder <NUM> and strut piston <NUM> may, for example, be configured to seal such that liquid contained within strut cylinder <NUM> is prevented from leaking as strut piston <NUM> translates relative to strut cylinder <NUM>. Further, strut cylinder <NUM> may be configured to contain a gas such as nitrogen gas or air. Shock strut <NUM> may comprise a proximal end <NUM> and a distal end <NUM>, wherein the distal end <NUM> is opposite the proximal end <NUM>, the distal end <NUM> being the end of the shock strut closest to a wheel or wheel assembly of a vehicle. A gas chamber may be positioned above an oil chamber (referred to as an "air-over-oil" arrangement) or vice versa, where the term "above" in this context means in the direction of the proximal end <NUM> of the shock strut <NUM>. Similarly, strut cylinder <NUM> and strut piston <NUM> may be sealed such that gas is prevented from leaking as strut piston <NUM> moves relative to strut cylinder <NUM>. As such, shock strut <NUM> may comprise a pressurized environment within strut cylinder <NUM>.

In various embodiments, the strut cylinder <NUM> may comprise a hollow circular tube having various components disposed within. Strut cylinder <NUM> may comprise a strut chamber <NUM>. Strut cylinder <NUM> may comprise an orifice support tube <NUM>. Orifice support tube <NUM> may comprise a hollow tube having a plurality of orifices through which oil or gas may travel. In this regard, orifice support tube <NUM> may comprise a tube channel <NUM> in fluid communication with strut chamber <NUM>. In this regard strut chamber <NUM> may comprise tube channel <NUM> defined by orifice support tube <NUM>. Various fluids may be disposed in strut chamber <NUM>. Air may be disposed within strut chamber <NUM>. Oil may be disposed within strut chamber <NUM>, whether alone or in combination with a gas such as air or nitrogen gas.

In various embodiments, strut piston <NUM> may comprise a hollow circular tube. At least a portion of strut piston <NUM> may be received by open end <NUM> of strut cylinder <NUM>. Strut piston <NUM> may comprise a metering pin <NUM>. Metering pin <NUM> may move with strut piston <NUM> with respect to strut cylinder <NUM>. Metering pin <NUM> may be received in orifice support tube <NUM>. Strut piston <NUM> may be reciprocally received within the strut cylinder <NUM>. In various embodiments, strut piston <NUM> may be reciprocally received within strut cylinder <NUM> in a concentric relationship with and between the strut cylinder <NUM> and orifice support tube <NUM>. In various embodiments, one or more bearings may be disposed between strut cylinder <NUM> and strut piston <NUM> against which the strut piston <NUM> slides.

In various embodiments, metering pin <NUM> may comprise a first end <NUM> (also referred to herein as a proximal end) and a second end <NUM> (also referred to herein as a distal end). Second end <NUM> may be coupled to strut piston <NUM>. First end <NUM> may be received into orifice support tube <NUM>. In various embodiments, the strut cylinder <NUM> may comprise a non-metallic orifice plate <NUM> (also referred to herein as an orifice plate). Metering pin <NUM> may be received by orifice plate <NUM>. Metering pin <NUM> may slide against an inner diameter (ID) surface of orifice plate <NUM>. In this regard, metering pin <NUM> may extend through orifice plate <NUM>.

With reference to <FIG>, an enlarged view of orifice plate <NUM> installed in shock strut <NUM> is illustrated, in accordance with various embodiments. In various embodiments, orifice plate <NUM> may be coupled to orifice support tube <NUM>. Orifice plate <NUM> may be disposed in orifice support tube <NUM>. The outer portion (i.e., at outer diameter (OD) surface <NUM>) of orifice plate <NUM> may be coupled to orifice support tube <NUM>. A threaded fastener <NUM> may be coupled to the open end <NUM> of orifice support tube <NUM>. Orifice plate <NUM> may float between threaded fastener <NUM> and orifice support tube <NUM>.

According to the invention, orifice plate <NUM> is made of a non-metallic material, comprising a thermoplastic or a thermoset carbon fiber reinforced composite. Orifice plate <NUM> comprises an inner diameter (ID) surface <NUM> and an outer diameter (OD) surface <NUM>. Orifice plate <NUM> comprises a wear surface <NUM>. Wear surface <NUM> defines the ID surface <NUM> of orifice plate <NUM>. Wear surface <NUM> may provide a wear resilient surface against which metering pin <NUM> may slide. In this manner, orifice plate <NUM> may provide weight-savings while maintaining wear resistance at ID surface <NUM>.

Orifice plate <NUM> comprises a first side surface <NUM> extending between the inner diameter surface <NUM> and the outer diameter surface <NUM>. Orifice plate <NUM> comprises a second side surface <NUM> extending between the inner diameter surface <NUM> and the outer diameter surface <NUM>. The second side surface <NUM> is disposed opposite the orifice plate <NUM> from the first side surface <NUM>.

In various embodiments, metering pin <NUM> may be hollow. In various embodiments, metering pin <NUM> may comprise a plurality of channels <NUM> extending axially along the outer surface of metering pin <NUM> whereby a flow of a fluid between strut piston <NUM> and strut cylinder <NUM> is metered, with momentary reference to <FIG>. Plurality of channels <NUM> may extend parallel with centerline axis <NUM> of metering pin <NUM>. In this regard, a fluid may flow from within strut piston <NUM> to strut chamber <NUM>, via plurality of channels <NUM>, in response to shock strut <NUM> moving towards a compressed position. Inversely, the fluid may flow from within strut chamber <NUM> to strut piston, via plurality of channels <NUM>, in response to shock strut <NUM> moving towards an extended position. The size of each channel <NUM> may vary along the length of metering pin <NUM> such that the flow of the fluid between strut chamber <NUM> and strut piston <NUM> is metered dependent upon the position of strut piston <NUM> with respect to strut cylinder <NUM>. For example, the depth of each channel <NUM> may be greater at first end <NUM> and may decrease in depth along the length of metering pin <NUM> towards second end <NUM>. In this manner, metering pin <NUM> and orifice plate <NUM> may work together to meter a flow of fluid traveling between metering pin <NUM> and orifice plate <NUM>, through channels <NUM>, within shock strut <NUM>.

With reference to <FIG>, an isometric view of orifice plate <NUM> is illustrated, in accordance with various embodiments. Orifice plate <NUM> comprises a body portion <NUM> comprising an annular geometry. In various embodiments, orifice plate <NUM> may comprise a wear-resistant material, such as polytetrafluoroethylene (PTFE) or a metal such as an electroless nickel plating, a bronze-based coating, a copper-based coating, or the like. In this regard, the ID surface <NUM> is wear-resistant to mitigate wear of ID surface <NUM> in response to metering pin <NUM> sliding against ID surface <NUM>.

With reference to <FIG>, a section view of an orifice plate <NUM> is illustrated, in accordance with various embodiments. Orifice plate <NUM> may be similar to orifice plate <NUM> of <FIG>. Orifice plate <NUM> comprises a body portion <NUM> and a wear-resistant coating <NUM> disposed on the ID surface <NUM> of body portion <NUM>. In this regard, wear-resistant coating <NUM> defines the ID surface <NUM> of orifice plate <NUM>. In various embodiments, wear-resistant coating <NUM> may be a thin-layer, wear-resistant coating comprising a thickness T1 of less than <NUM> millimeters (<NUM> inches). In various embodiments, the thickness T1 of wear-resistant coating <NUM> may be less than <NUM> millimeters (<NUM> inches). Wear-resistant coating <NUM> may be applied to ID surface <NUM> of body portion <NUM> using an electroplating process, an electroless plating process, a thermal spray process, physical vapor deposition (PVD), chemical vapor deposition (CVD), or any other suitable coating process.

In various embodiments, body portion <NUM> is comprised of a lightweight thermoplastic material, such as polyethylene (PE), polypropylene, polyvinyl chloride (PVC), or the like. According to the invention, body portion <NUM> is comprised of a thermoset carbon fiber reinforced composite. In this regard, body portion <NUM> may result in reduced weight of the overall shock strut <NUM> as compared to orifice plates comprised of a metal material or other material which is heavier, per unit volume, than a thermoplastic material or a thermoset carbon fiber reinforced composite. In various embodiments, wear-resistant coating <NUM> is comprised of a wear-resistant material, such as polytetrafluoroethylene, or a metal, for example. In this manner, orifice plate <NUM> may provide weight-savings while maintaining wear resistance at ID surface <NUM>.

With reference to <FIG>, a section view of an orifice plate <NUM>, not part of the present invention, is illustrated, in accordance with various examples, Orifice plate <NUM> may be similar to orifice plate <NUM> of <FIG>. Orifice plate <NUM> may comprise a body portion <NUM> and a wear-resistant insert <NUM> coupled to the ID surface <NUM> of body portion <NUM>. In this regard, wear-resistant insert <NUM> may define the ID surface <NUM> of orifice plate <NUM>. In various examples body portion <NUM> is comprised of a lightweight thermoplastic material, such as polyethylene (PE), polypropylene, polyvinyl chloride (PVC), or the like. In various embodiments, body portion <NUM> is comprised of a thermoset carbon fiber reinforced composite. In this regard, body portion <NUM> may result in reduced weight of the overall shock strut <NUM> as compared to orifice plates comprised of a metal material or other material which is heavier, per unit volume, than a thermoplastic material or a thermoset carbon fiber reinforced composite. In various examples wear-resistant insert <NUM> may be comprised of a wear-resistant material, such as polytetrafluoroethylene for example. In this manner, orifice plate <NUM> may provide weight-savings while maintaining wear resistance at ID surface <NUM>.

In various examples not part of the present invention, wear-resistant insert <NUM> comprises an ID surface <NUM> and an OD surface <NUM>. The OD surface <NUM> may mate against ID surface <NUM> of body portion <NUM>. In various examples OD surface <NUM> of wear-resistant insert <NUM> is coupled to ID surface <NUM> via a friction welding process. Stated differently, wear-resistant insert <NUM> may be friction welded to body portion <NUM>. In various examples OD surface <NUM> of wear-resistant insert <NUM> is coupled to ID surface <NUM> via an adhesive. Stated differently, wear-resistant insert <NUM> may be adhered to body portion <NUM>.

With reference to <FIG>, a flow chart providing a method <NUM> for manufacturing an orifice plate is illustrated, in accordance with various embodiments. Method <NUM> include forming a body portion of an orifice plate comprising a first material (step <NUM>). Method <NUM> includes forming a wear-resistant inner diameter surface comprising a second material (step <NUM>). Step <NUM> may be performed subsequent to step <NUM>.

With combined reference to <FIG>, <FIG>, step <NUM> may include forming body portion <NUM>. Step <NUM> may include forming body portion <NUM>. Body portion <NUM> and body portion <NUM> may be formed using any suitable process including additive manufacturing methods, subtractive manufacturing methods, a molding process, or any combination thereof. Body portion <NUM> and/or body portion <NUM> comprises a first material such as a thermoset carbon fiber reinforced composite or a thermoplastic material, including a polyethylene (PE), a polypropylene, a polyvinyl chloride (PVC), or the like.

Step <NUM> includes applying wear-resistant coating <NUM> on ID surface <NUM> of body portion <NUM> to form wear-resistant ID surface <NUM>. Wear-resistant coating <NUM> may be formed using any suitable process including electroplating, electroless plating, thermal spraying, physical vapor deposition (PVD), chemical vapor deposition (CVD), or any other suitable coating process. In an alternative solution, not covered by the present invention, Step <NUM> may include coupling wear-resistant insert <NUM> to body portion <NUM> to form wear-resistant ID surface <NUM>. The outer diameter of wear-resistant insert <NUM> may be substantially equal to the inner diameter of body portion <NUM>. Wear-resistant insert <NUM> may be coupled to body portion <NUM> using any suitable process including friction welding, using adhesive, or the like. Wear-resistant coating <NUM> and/or wear-resistant insert <NUM> comprises a second material, different from the first material. The second material is a wear-resistant material such as a polytetrafluoroethylene or the like.

Claim 1:
A shock strut, comprising:
a strut cylinder (<NUM>);
a strut piston (<NUM>) operatively coupled to the strut cylinder;
a non-metallic orifice plate (<NUM>) comprising a body portion (<NUM>) having an annular geometry; and
a metering pin (<NUM>) extending through the non-metallic orifice plate;
the body portion (<NUM>) of the non-metallic orifice plate comprising:
an inner diameter surface (<NUM>);
an outer diameter surface (<NUM>);
a first side surface (<NUM>) extending between the inner diameter surface and the outer diameter surface; and
a second side surface (<NUM>) extending between the inner diameter surface and the outer diameter surface, the second side surface disposed opposite the non-metallic orifice plate from the first side surface; and
a wear-resistant coating (<NUM>) disposed on the inner diameter surface of the body portion, wherein the wear-resistant coating defines a wear-resistant inner diameter surface on the non-metallic orifice plate; and wherein
the body portion (<NUM>) comprises a first material; and
wherein the wear-resistant coating comprises a second material;
wherein the first material comprises at least one of a thermoplastic and a thermoset carbon fiber reinforced composite.