Patent Description:
Various valves are used for controlling and/or selectively permitting fluid flow between a source and a wet component, for example check valves which are used to open or close an oil path from a reservoir to a bearing in a gearbox. The opening and closing of such check valves can be triggered by various mechanisms. While existing valves may suit their intended purpose, there remains room for improvement in the art, for instance where space, weight and/or part count pertaining to such valves are design concerns.

<CIT> discloses a prior art valve for use in a fluid system as set forth in the preamble of claim <NUM>.

<CIT> discloses a prior art ducted gas turbine engine stability bleed valve with passive and active shutoff.

There is accordingly provided a valve for use in a fluid system as recited in claim <NUM>.

There is also provided a fluid system for a gas turbine engine as recited in claim <NUM>.

<FIG> illustrates an aircraft engine <NUM> of a type preferably provided for use in subsonic flight, such as for example a gas turbine engine generally comprising in serial flow communication a fan <NUM> through which ambient air is propelled, a compressor section <NUM> for pressurizing the air, a combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section <NUM> for extracting energy from the combustion gases.

Although the present technology will generally be described in an exemplary manner with respect to an oil system <NUM> of the engine <NUM>, it shall be understood that it may also be implemented, mutatis mutandis, in any other fluid system of the engine <NUM>, such as for example a fuel system. Additionally, the valves as described herein may also be implemented in other types of fluid systems.

<FIG> illustrates an oil system <NUM> for the engine <NUM>, comprising a reservoir <NUM>, a wet cavity <NUM> downstream of the reservoir <NUM>, a pump <NUM> in fluid communication between the reservoir <NUM> and the wet cavity <NUM> and a valve <NUM> in fluid communication between the pump <NUM> and the wet cavity <NUM>. The valve <NUM> is also in fluid communication with a return line <NUM>, itself in fluid communication with the reservoir <NUM>, via which the valve <NUM> may drain, for example upon the engine <NUM> shutting down.

The valve <NUM> and others described herein are so-called "pressure referenced" valve (or simply "referenced" valve), and thus is actuated to open or close based on, or in reference to, a pressure reference schematically shown at <NUM>, for example a sensed fluid pressure somewhere in the fluid system. Indeed, a referenced valve may be configured to open when the pressure of the fluid at a certain point in the fluid system (not necessarily on either side of the valve itself) reaches a threshold pressure value. The pressure reference <NUM> can in some cases be located at the reservoir <NUM> or at the wet cavity <NUM>. Suitable locations for the pressure reference <NUM> within the fluid system include a fluid tank, a bearing cavity, and a gearbox, among others. Nevertheless, the pressure reference <NUM> can also be external to the fluid system, and may be located for example in the main gas path of the engine <NUM> at the compressor section <NUM>. Various other suitable locations for the pressure reference <NUM> are also possible, depending on the implementation of the valve <NUM>. The pressure reference <NUM> may be a location at which the pressure is the lowest of any location of the fluid system, which may minimize a pressure drop of the fluid flowing across the valve <NUM>.

The valve <NUM> therefore has a pressure reference port R in fluid communication with the pressure reference <NUM>, and is configured to operate (i.e., open or close) as a function of system pressures exerted onto the valve <NUM> such as a pressure exerted by the pump <NUM> and a pressure exerted by the pressure reference <NUM> via the reference port R.

With reference to <FIG>, the valve <NUM> will be described in greater detail. As illustrated in <FIG>, the valve <NUM> includes a housing <NUM> having an upstream end <NUM>a of the valve <NUM> defining an inlet passage PI, or inlet port, and a downstream end <NUM>b of the valve <NUM> defining an outlet passage PO, or outlet port. In this embodiment, the housing <NUM> has a cylindrical shape and extends along a longitudinal axis A that extends through the valve <NUM>. The upstream and downstream ends <NUM>a, <NUM>b project from opposite ends of the housing <NUM> in opposite directions parallel to the axis A, defining spouts sealingly receivable by fluid conduits 20a, 20b (<FIG>, <FIG>) of the oil system <NUM> respectively located upstream and downstream of the valve <NUM>. In certain other embodiments, the upstream and downstream ends <NUM>a, <NUM>b are arranged for sealingly receiving the fluid conduits 20a, 20b. In yet other embodiments, the housing <NUM> is embedded in another housing-type structure of the oil system <NUM> (for example an oil pump housing, an oil tank housing, a bearing cavity housing, a gearbox cavity housing, etc.) defining either conduit 20a, 20b, and may be said to form a unitary piece therewith.

On the inside, the housing <NUM> defines a chamber C along the axis A having an upstream end in fluid communication with the inlet passage PI and a downstream end in fluid communication with the outlet passage PO. The reference port R of the valve <NUM> is defined by the housing <NUM> and is in fluid communication with inside the chamber C. A piston assembly <NUM> of the valve <NUM> is sealingly received by the chamber C so as to close the chamber C at either end. The piston assembly <NUM>, as will be described, is structured and arranged so as to be clear of a portion of the chamber C that is in fluid communication with the reference port R. Radially outward of the chamber C relative to the axis A, the housing <NUM> defines an axially-extending passage referred to as a bypass passage PA. The bypass passage PA extends besides the chamber C away from the upstream end <NUM>a and toward the downstream end <NUM>b. Upstream of the chamber C, the housing <NUM> defines a radially-extending upstream passage PRa extending from the inlet passage PI to an upstream end of the bypass passage PA. Downstream of the chamber C, the housing <NUM> defines a radially-extending downstream passage PRb extending from a downstream end of the bypass passage PA to the outlet passage PO. The inlet passage PI, the upstream passage PRa, the bypass passage PA, the downstream passage PRb and the outlet passage PO are in serial flow communication so as to define a flow path through the valve <NUM>. The flow path may be said to be routed through the valve <NUM> so as to circumvent the chamber C and the reference port R as it extends from the upstream end <NUM>a to the downstream end <NUM>b of the valve <NUM>. The piston assembly <NUM> is arranged relatively to the housing <NUM> so as to selectively obstruct the flow path at the upstream passage PRa, as will be described hereinbelow.

In <FIG>, the valve <NUM> is shown disassembled and circumferentially cutaway so as to exhibit interior features. As shown in <FIG>, the housing <NUM> has an interior-housing wall <NUM> defining a housing cavity about the axis A in fluid communication between the inlet passage PI and the outlet passage PO. The housing <NUM> also has a tubular rim <NUM> located in the housing cavity about the axis A. An exterior of the rim <NUM> defines the bypass passage PA, whereas an interior of the rim <NUM> defines the chamber C. The bypass passage PA is circumscribed radially outwardly by the inner-housing wall <NUM> and radially inwardly by the rim <NUM> relative to the axis A. It shall be noted that in this embodiment, the rim <NUM> is axially shorter than the inner-housing wall <NUM>. Moreover, an upstream end <NUM>a and a downstream end <NUM>b of the inner-housing wall <NUM> are respectively axially spaced outwardly from an upstream end <NUM>a and a downstream end <NUM>b of the rim <NUM>, leaving portions of the bypass passage PA radially inwardly unenclosed at either end of the rim <NUM>. This arrangement of the rim <NUM> relative to the inner-housing wall <NUM> defines portions of the upstream passage PRa and the downstream passage PRb, which may also be referred to as housing windows defined by the housing <NUM> radially through the rim <NUM> on either side of the chamber C. In some embodiments, the rim <NUM> extends axially to either one or both of the ends <NUM>a, <NUM>b of the inner-housing wall <NUM>, and the housing windows are openings defined in a portion of the rim <NUM> surrounded by the inner-housing wall <NUM>.

The housing <NUM> is also provided with at least one web-like member, henceforth referred to as a rib <NUM>, which extends radially outwardly relative to the axis A from the rim <NUM> to the inner-housing wall <NUM>. Depending on the embodiment, a plurality of ribs <NUM> being circumferentially spaced apart from one another can be provided. The plurality of ribs <NUM> partition the bypass passage PA into a plurality of axially-extending channels. For example, in this embodiment, two ribs <NUM> located diametrically opposite one another are provided (<FIG>) to support the rim <NUM> relative to the inner-housing wall <NUM>, and define, together with the rim <NUM>, a pair of C-shaped channels. In some embodiments, more than two channels are provided. In some embodiments, the channels have a cylindrical shape (<FIG>). The housing <NUM> also defines an annular housing seat <NUM> surrounding a downstream end of the inlet passage PI, by way of which the housing <NUM> engages with the piston assembly <NUM> as will now be described.

Still referring to <FIG>, the piston assembly <NUM> includes a piston <NUM>, a base <NUM>, a biasing means (not shown) between the piston <NUM> and the base <NUM> and a sleeve <NUM> by which the piston <NUM> is slidably received. A first sleeve end of the sleeve <NUM> is sealingly received by the housing seat <NUM> and a second sleeve end of the sleeve <NUM> is sealingly received by the rim <NUM> within the chamber C. The sleeve <NUM> thus extends from inside the chamber C to the inlet passage PI, thereby extending across the upstream passage PRa. An inner-sleeve wall 126a of the sleeve <NUM> defines an annular sleeve seat 126b located proximate to the first sleeve end on the inside of the sleeve <NUM>. Between the sleeve seat 126b and the second sleeve end, slot-like openings, referred to henceforth as sleeve windows 126c, extend from inside the sleeve <NUM> to outside thereof. Upon the sleeve <NUM> being received by the housing seat <NUM>, the sleeve windows 126c longitudinally align with and circumferentially overlap the housing windows, such that fluid flowing through the flow path may flow through the sleeve windows 126c. Preferably, an overlap area of the sleeve windows 126c relative to the housing windows corresponds to at least a cross sectional area of the inlet passage PI or the outlet passage PO, whichever is the lesser, such that the sleeve windows 126c are not a restrictor of the flow path. Here, as best seen in <FIG>, three similarly shaped and equally spaced apart sleeve windows 126c are provided, in what is merely one of numerous suitable configurations of the sleeve <NUM>. The base <NUM> is fastened to the housing <NUM>, in this case via the rim <NUM>, so as to hold the sleeve <NUM>, with the piston <NUM> therein, in place relative to the housing <NUM>.

Referring to <FIG>, the piston <NUM> is movable relative to the housing <NUM> between a first valve position (<FIG>) in which the piston <NUM> obstructs the flow path at the upstream passage PRA and a second valve position (<FIG>) in which the piston <NUM> is at least partially clear of the flow path. The first and second valve positions may thus be respectively referred to as a closed position and an open position of the valve <NUM>. In the first valve position, the piston <NUM> encroaches the upstream passage PRa. A first piston end 122a, or tip, of the piston <NUM> engages the sleeve seat 126b and blocks the flow path at the inlet passage PI. Preferably, the first piston end 122a has a shape complementary to that of the sleeve seat 126b. A portion of the piston <NUM> proximate to the first piston end 122a blocks the flow path at the sleeve windows 126c. In some embodiments, the sleeve <NUM> is omitted, and the piston is slidably received by the rim <NUM>. In such embodiments, the first piston end 122a engages the housing seat <NUM> when in the closed valve position so as to block the flow path at the inlet passage PI.

The biasing means, in this case provided in the form of a spring having opposite ends respectively engaging the base <NUM> and a second piston end 122b of the piston <NUM>, biases the piston <NUM> toward the first valve position under a certain biasing force. The biasing force is selected to be suitable for biasing the piston <NUM> in the first valve position upon any pressures exerted by fluids against the piston <NUM> being either balanced or absent, as the case may be during shutdown of the engine <NUM>. The biasing force can be adjusted by any suitable way, such as by adjusting mechanical properties of the spring including a nominal length and/or stiffness of the spring. Conversely, this can be done by replacing the spring with another having a different length and/or stiffness, but also by way of a spacing means, such as one or more shims, inserted at one or both ends of the spring. In the depicted embodiment, the second piston end 122b defines a recess 122c, and the biasing means engages a bottom surface of the recess 122c. Proximate to the second piston end 122b and the base <NUM>, a portion of the chamber C partially enclosed by the piston assembly <NUM> is in fluid communication with the reference port R. A reference fluid, which may be oil or a gas, is injected in the chamber C via the reference port R, thereby further urging the piston <NUM> toward the first position. Thus, to move the piston <NUM> from the first valve position to the second valve position, a force greater than the sum of those exerted by the spring and by the reference fluid against the second piston end 122b must be exerted against the first piston end 122a. Hence, the spring can be adjusted such that the piston <NUM> requires a pressure greater than that in effect at the reference port R by a predetermined amount in order to be moved from the first valve position to the second valve position. Increasing the stiffness of the spring can in some cases desirably lessen the effect of sudden pressure variations, such as a sudden pressure drop at the reference port R or a sudden pressure increase at the inlet passage PI. In some embodiments, the biasing means is omitted, such that the piston <NUM> is biased toward the first valve position under the sole influence of the reference fluid, provided that a suitable pressure is in effect at the reference port R.

Whereas conventional referenced valves have their outlet located between their inlet and their pressure reference port, it should be noted that the flow path defining features described hereinabove allow circumvention of the reference port R by the flow path, such that the reference port R may be located between the inlet passage PI and the outlet passage PO, i.e., at a location axially closer to the inlet passage PI than a location of the outlet passage PO. This renders possible various spatial arrangements of the inlet passage PI and of the outlet passage PO relative to one another. For example, in this exemplary embodiment, the inlet passage PI and the outlet passage PO respectively extend along an inlet axis and an outlet axis that are collinear to the axis A. Stated otherwise, the inlet passage PI, the chamber C and the outlet passage PO are concentric. In other embodiments, one or both of the inlet axis and the outlet axis may be at an angle to the axis A or transversely offset relative to the axis A.

Moreover, in this exemplary embodiment, the housing <NUM> is constructed of multiple pieces structured and arranged such that one such piece defining the chamber C is detachable from another such piece defining one of the upstream and downstream ends <NUM>a, <NUM>b of the valve <NUM>. In this particular arrangement, the housing <NUM> includes a body <NUM> having the upstream end <NUM>a of the valve <NUM>, and a tubular member, referred to henceforth as a transfer tube <NUM>, having the downstream end <NUM>b of the valve <NUM> and being detachable from the body <NUM>. The transfer tube <NUM> extends along the outlet axis. The transfer tube <NUM> has a proximal tube portion <NUM> slidably received by the body <NUM> alongside the inner-housing wall <NUM>, and a distal tube portion <NUM> defining the outlet passage PO. In other embodiments, the body <NUM> is instead slidably received by the proximal tube portion <NUM>. As it extends axially from the proximal tube portion <NUM> to the distal tube portion <NUM>, the transfer tube <NUM> tapers and cooperates with the body <NUM> to define the downstream passage PRb. In other embodiments, the downstream passage PRb is fully defined by the body <NUM>, and the transfer tube <NUM> is located downstream thereof.

An axial length of the valve <NUM> is selectively variable, and various means can be used to selectively position the transfer tube <NUM> relative to the body <NUM>. For instance, referring to <FIG>, an annular body flange <NUM> of the body <NUM> extending radially outwardly relative to the inner-housing wall <NUM> can act as an abutment for limiting axial movement of the transfer tube <NUM> toward the upstream end <NUM>a of the valve <NUM>. A C-clip (or other like fastener) engaged in an annular, radially outer tube groove <NUM> defined by the proximal tube portion <NUM> can abut the body flange <NUM>, thereby stopping the transfer tube <NUM>. As shown in <FIG>, in certain embodiments, the proximal tube portion <NUM> can define a plurality of tube grooves <NUM> spaced from one another, each allowing to selectively place the C-clip to stop the transfer tube <NUM> at a different offset relative to the body <NUM>. Alternatively, as shown in <FIG>, the proximal tube portion <NUM> may be threadedly engaged with a nut <NUM> disposed therearound, and abut the body flange <NUM> via the nut <NUM>. Conversely, axial movement of the transfer tube <NUM> away from the upstream end <NUM>a of the valve <NUM> can be limited by any one of several suitable means. For example, as shown in <FIG>, the body <NUM> may have an axially-extending wall <NUM> located radially outward of the flange <NUM> defining an annular, radially inner body groove <NUM> by which a C-clip (or other like fastener) may be received. The C-clip may engage the transfer tube <NUM> directly or indirectly via another C-clip fitted thereto. Alternatively, as shown in <FIG>, a flanged nut <NUM> threadedly engaged with the body <NUM> may be used to limit the outward movement of the transfer tube <NUM>.

Referring to <FIG>, the valve <NUM> is shown in a retracted position, in which the transfer tube <NUM> is received by the body <NUM> such that the axial length, i.e., a distance between the upstream and downstream ends <NUM>a, <NUM>b of the valve <NUM>, is minimized. In the retracted position, the proximal tube portion <NUM> is received by an annular, axially-extending recess <NUM> defined by the body <NUM> at a location radially inward of the inner-housing wall <NUM> and axially inward the ribs <NUM>. The recess <NUM> is also shown in <FIG>. In <FIG>, the valve <NUM> is shown in an extended position in which the transfer tube <NUM> is held relative to the body <NUM> such that the axial length, i.e., the distance between the upstream and downstream ends <NUM>a, <NUM>b of the valve <NUM>, is maximized. In this arrangement, the extended position corresponds to a distance between fixed ends of the fluid conduits 20a, 20b of the oil system <NUM>. The valve <NUM> may be aligned with the fluid conduits 20a, 20b upon being in the retracted position and, once in alignment, be moved into the extended position to connect to the fluid conduits 20a, 20b. In embodiments, the body <NUM> is integral to a housing defining the fixed end of the fluid conduit 20a. In embodiments, the transfer tube <NUM> is integral to a housing defining the fixed end of the fluid conduit 20b.

With reference to <FIG>, another embodiment of the present technology will now be described, in which the outlet passage PO is a first outlet passage PO1, and the inlet passage PI, the upstream passage PRa, the axial passage PA, the downstream passage PRb and the first outlet passage PO are in serial flow communication so as to define a first flow path through the valve <NUM>. In this embodiment, the housing <NUM> defines a second outlet passage PO2 located axially between the inlet passage PI and the reference port R. The second outlet passage PO2 is in fluid communication with the inlet passage PI, at a location upstream of the upstream passage PRa, defining a second flow path therewith through the valve <NUM>. The second flow path may for example be upstream of the return line <NUM>.

In this embodiment, the first piston end 122a is hollow. Stated otherwise, the piston <NUM> has a hollow piston portion extending from the first piston end 122a toward the second piston end 122b. The piston <NUM> defines a port 122d extending radially outwardly from inside the hollow piston portion to outside the piston <NUM>. The piston <NUM> is movable relative to the housing <NUM> between a first valve position (<FIG>) and a second valve position (<FIG>). In the first valve position, the piston <NUM> at least partially obstructs the first flow path at the upstream passage PRA, yet remains at least partially clear of the second flow path as the port 122d communicates with the second outlet passage PO2. The inlet passage PI is in fluid communication with the second outlet passage PO2 via the hollow piston portion. In the second valve position, the piston <NUM> at least partially obstructs the second flow path yet remains at least partially clear of the first flow path as the port 122d communicates with the first outlet passage PO1. The inlet passage PI is in fluid communication with the first outlet passage PO1 via the hollow piston portion. Hence, fluid may flow through the valve <NUM> regardless of the position of the piston <NUM>. In some embodiments, most but not all of the flow of fluid entering the valve <NUM> via the inlet passage PI exits the valve <NUM> via the second outlet passage PO2 when the piston <NUM> is in the first valve position, and exits the valve <NUM> via the first outlet passage PO1 when the piston <NUM> is in the second valve position. In some such embodiments, fluid exits the valve <NUM> at a given rate regardless of the position of the piston <NUM>. In some other embodiments such as the one depicted in <FIG>, the valve <NUM> is referred to as a bypass valve, i.e., <NUM>% of the fluid entering the valve <NUM> via the inlet passage PI exits the valve <NUM> via the second outlet passage PO2 when the piston <NUM> is in the first valve position, and exits the valve <NUM> via the first outlet passage PO1 when the piston <NUM> is in the second valve position.

Claim 1:
A valve (<NUM>) for use in a fluid system (<NUM>), the valve (<NUM>) comprising:
a housing (<NUM>) having an inlet passage (PI), an outlet passage (PO) axially spaced apart from the inlet passage (PI) relative to a longitudinal axis (A) extending through the housing (<NUM>), and a pressure reference port (R) located axially between the inlet passage (PI) and the outlet passage (PO), the housing (<NUM>) including:
an inner-housing wall (<NUM>) enclosing a housing cavity providing fluid communication between the inlet passage (PI) and the outlet passage (PO);
a rim (<NUM>) in the housing cavity extending circumferentially about the longitudinal axis (A), the rim (<NUM>) defining an axially-extending bypass passage (PA) circumscribed radially outwardly by the inner-housing wall (<NUM>) and radially inwardly by the rim (<NUM>), a radially-extending upstream passage (PRa) located axially between an upstream end of the housing cavity and the rim (<NUM>), and a radially-extending downstream passage (PRb) located axially between the rim (<NUM>) and a downstream end of the housing cavity, wherein the inlet passage (PI), the upstream passage (PRa), the bypass passage (PA), the downstream passage (PRb) and the outlet passage (PO) are in serial flow communication so as to define a flow path through the valve (<NUM>);
a chamber (C) circumscribed radially outwardly by the rim (<NUM>), the chamber (C) in fluid communication with the pressure reference port (R);
a rib (<NUM>) extending radially outwardly from the rim (<NUM>) to the inner-housing wall (<NUM>), through the bypass passage (PA); and
a piston assembly (<NUM>) received within the chamber (C), the piston assembly (<NUM>) including a piston (<NUM>) movable axially relative to the rim (<NUM>) between a first valve position in which the piston (<NUM>) obstructs the flow path at the upstream passage (PRa) and a second valve position in which the piston (<NUM>) is at least partially clear of the flow path to permit fluid flow along the flow path,
wherein the housing (<NUM>) includes a body (<NUM>) defining the inlet passage (PI), characterised in that:
the housing (<NUM>) includes a transfer tube (<NUM>) defining the outlet passage (PO), the transfer tube (<NUM>) slidably received by the body (<NUM>); and
the axial length of the valve (<NUM>) is selectively variable, wherein means are provided to selectively position the transfer tube (<NUM>) relative to the body (<NUM>).