Patent Description:
Valves for controlling fluid flow are ubiquitous in the art. Valves may be electrically controlled, hydraulically controlled, mechanically controlled, and/or pressure controlled. All valves inherently have a hysteresis or, a difference in signal level between activation signal (to move from a first to a second position) and a deactivation signal (to move back from the second position to the first). Hysteresis may depend on friction, application pressures, and other properties of the valve. One example of hysteresis is a solenoid valve electrically opening at <NUM> mA, but closing again at <NUM> mA, for a hysteresis of <NUM> mA.

Typically, electrically activated valves such as solenoid valves possess a low hysteresis and pressure activated valves, such as ball valves have a higher hysteresis. Frictional forces, flow forces, and pressure application time associated with moving a ball off of a ball seat and then back again lead to a higher hysteresis. Slower control responses associated with a high hysteresis can lead to undesirable valve leakage, process cycling, and control variances. However, there is a desire for low hysteresis pressure activated valves such that valves can be passively controlled. <CIT> describes a differential pressure type inflating device. <CIT> describes a valve assembly. <CIT> describes an overfill valve with an actuated obturator. <CIT> describes an inline air valve nose cap for reduced contamination. <CIT> describes a pneumatically controllable valve assembly, tire inflation system, and methods of operating the valve assembly system, and tire inflation system. <CIT> describes a pneumatic two-component pump chain shutdown control mechanism.

Disclosed in accordance with a non-limiting example is a pressure actuated switching valve according to claim <NUM> including a valve chamber including a first chamber portion defining an inlet, the first chamber portion having a first inner diameter, a second chamber portion defining an outlet, the second chamber portion having a second inner diameter that is greater than the first inner diameter, a first sealing surface defined between the first chamber portion and the second chamber portion, a third chamber portion having a third inner diameter that is greater than the first inner diameter, a fourth chamber portion having a fourth inner diameter that is greater than first inner diameter, a fifth chamber portion, a second sealing surface defined at an interface of the fourth chamber portion and the fifth chamber portion, and a valve member slidingly arranged in the valve chamber. The valve member includes a first section arranged in the second chamber portion. The first section has a first outer diameter that is greater than the first inner diameter and is configured to selectively engage the first sealing surface. A second section of the valve member is arranged in the third chamber portion. The second section has a second outer diameter that is closely matched to the third inner diameter. A third section of the valve member is arranged in the fourth chamber portion, the third section has a third outer diameter that is greater than the first outer diameter, the second outer diameter, and the second inner diameter, and is configured to selectively engage the second sealing surface.

Additionally, in this or other non-limiting examples a spring arranged in the fifth chamber portion, the spring engaging the third section of the valve member, wherein the spring biases the valve member toward the sealing surface.

Additionally, in this or other non-limiting examples the valve chamber includes a first chamber section and a second chamber section, wherein the first chamber section is mechanically connected to the second chamber section.

Additionally, in this or other non-limiting examples, the first chamber section is selectively detachably connected to the second section.

Additionally, in this or other non-limiting examples, the third section of the valve member is detachably connected to the second section of the valve member.

Additionally, in this or other non-limiting examples, the second outer diameter is greater than the first outer diameter.

Additionally,in this or other non-limiting examples, the third outer diameter is greater than the second outer diameter.

Additionally, in this or other non-limiting examples, a first end portion of the second section extends into the second chamber portion and a second end portion of the second section extends into the fourth chamber portion.

Also disclosed in accordance with a non-limiting example, is an aircraft according to claim <NUM> including a fuselage, at least one engine is supported by the fuselage, a mechanical system is arranged in the fuselage. The mechanical system includes a pressure actuated switching valve including a valve chamber including a first chamber portion defining an inlet, the first chamber portion having a first inner diameter, a second chamber portion defining an outlet, the second chamber portion having a second inner diameter that is greater than the first inner diameter, a first sealing surface defined between the first chamber portion and the second chamber portion, a third chamber portion having a third inner diameter that is greater than the first inner diameter, a fourth chamber portion having a fourth inner diameter that is greater than first inner diameter; a fifth chamber portion, a second sealing surface defined at an interface of the first chamber portion and the second chamber portion, and a valve member slidingly arranged in the valve chamber. The valve member includes a first section arranged in the second chamber portion, the first section having a first outer diameter that is greater than the first inner diameter and being configured to selectively engage the first sealing surface, a second section arranged in the third chamber portion, the second section having a second outer diameter that is closely matched to the third inner diameter, and a third section arranged in the fourth chamber portion having a third outer diameter that is greater than the first outer diameter, the second outer diameter, and the second inner diameter.

Additionally, in this or other non-limiting examples, a spring arranged in the fifth chamber portion, the spring engaging the third section of the valve member, wherein the spring biases the valve member toward the sealing surface.

Additionally, in this or other non-limiting examples, the valve chamber includes a first chamber section and a second chamber section, the first chamber section being mechanically connected to a second chamber section.

Additionally, in this or other non-limiting examples, the first chamber section is selectively detachably connected to the second chamber section.

Additionally, in this or other non-limiting examples, the third outer diameter is greater than the second outer diameter.

Further disclosed in accordance with a non-limiting example is a method of operating a pressure actuated switching valve according to claim <NUM>, the method including introducing a fluid into a valve chamber having a first chamber portion including a first inner diameter, a second chamber portion having a second inner diameter that is greater than the first inner diameter, a third chamber portion having a third inner diameter that is greater than the first inner diameter, a fourth chamber portion having a fourth inner diameter that is greater than first inner diameter, and a fifth chamber portion, snapping the pressure actuated switching valve open by unseating a first section of a valve member from a sealing surface defined between the first chamber and the second chamber portion with a first fluid pressure directed at the first section, holding the pressure actuated switching valve open with the first fluid pressure acting on the first section and a second fluid pressure acting on a third section of the valve member in the fifth chamber portion, passing a portion of the first fluid through an outlet connected to the second chamber portion, reducing the first fluid pressure, and snapping the valve member closed seating the first section on the sealing surface with a spring positioned in the fifth chamber portion.

Additionally, in this or other non-limiting examples, snapping the valve member closed includes applying pressure to the third section of the valve member.

Additionally, in this or other non-limiting examples, applying pressure to the third section includes applying a biasing force to the third section with a spring.

Additionally, in this or other non-limiting examples, snapping the pressure actuated switching valve open includes passing a fluid from the fifth chamber portion into the fourth chamber portion around the third section.

Additionally, in this or other non-limiting examples, preventing fluid in the fourth chamber portion from passing into the third chamber portion with a second section of the valve member disposed between the first section and the third section.

An aircraft in accordance with a non-limiting example is indicated generally at <NUM> in <FIG>. Aircraft <NUM> includes a fuselage <NUM> supporting a pair of wings, one of which is shown at <NUM>, and a tail <NUM>. Fuselage <NUM> defines, in part, a cabin <NUM> that accommodates crew and/or passengers. Wing <NUM> supports a first engine <NUM> and a second engine <NUM>. Fuselage <NUM> includes a cabin air system <NUM> that is connected to first engine <NUM>. Cabin air system <NUM> may also be connected to second engine <NUM>.

In a non-limiting example, cabin air system <NUM> includes an air intake <NUM> at first engine <NUM>, an air conditioner <NUM>, and an air mixing unit <NUM>. An air filter <NUM> filters air passing into an air circulation circuit <NUM>. An exhaust <NUM> discharges air from air circulation circuit <NUM> adjacent to tail <NUM>. A mechanical system, shown in the form of a bleed air valve <NUM> provides an interface between first engine <NUM> and air conditioner <NUM>.

In a non-limiting example shown in <FIG>, bleed air valve <NUM> includes a housing <NUM> including an inlet portion <NUM> and an outlet portion <NUM>. A controlling air inlet <NUM> projects outwardly from <NUM> between inlet portion <NUM> and outlet portion <NUM>. A valve member is disposed in housing <NUM>. Valve member selectively connected inlet portion <NUM> and outlet <NUM>. Valve member includes a hub <NUM> supported on a shaft <NUM> having a shaft axis "A". In a non-limiting example, valve member <NUM> transitions on shaft <NUM> along the shaft axis "A" to fluidically connect outlet <NUM> to air passing from first engine <NUM> through air inlet portion <NUM> based on provided pressure from controlling air inlet <NUM>.

In a non-limiting example, controlling air inlet <NUM> includes a pressure actuated switching valve <NUM> having an inlet <NUM> connected with upstream air from first engine <NUM> and an outlet <NUM> that is connected fluidly with shaft <NUM> such that the pressure at outlet <NUM> controls the position of valve member. In a non-limiting example shown in <FIG>, pressure actuated switching valve <NUM> includes a valve chamber <NUM> having a first chamber portion <NUM>, a second chamber portion <NUM>, a third chamber portion <NUM>, a fourth chamber portion <NUM>, and a fifth chamber portion <NUM>. In a non-limiting example, first chamber portion <NUM> is fluidically connected to inlet <NUM> and includes a first inner surface <NUM> defining a first inner diameter ID1, second chamber portion <NUM> is fluidically connected to outlet <NUM> and includes a second inner surface <NUM> having a second inner diameter ID2, third chamber portion <NUM> includes a third inner surface <NUM> defining a third inner diameter ID3, fourth chamber portion <NUM> includes a fourth inner surface <NUM> defining a fourth inner diameter ID4, and fifth chamber portion <NUM> includes a fifth inner surface <NUM> defining a fifth inner diameter ID5. In a non-limiting example, second chamber portion <NUM> includes a sealing surface <NUM> for the closed position. Fourth chamber portion <NUM> includes a sealing surface section <NUM> for the open position. Fifth chamber portion <NUM> includes a connection (not shown) to a downstream reference pressure, which could be ambient pressure.

In a non-limiting example, a valve member <NUM> is arranged in valve chamber <NUM>. Valve member <NUM> includes a first section <NUM>, a second section <NUM>, and a third section <NUM>. In a non-limiting example, first section <NUM> includes a first outer surface <NUM> having a first outer diameter "OD1", second section <NUM> includes a second outer surface <NUM> having a second outer diameter "OD2", and third section <NUM> includes a third outer surface <NUM> having a third outer diameter (OD3). In a non-limiting example, section <NUM> includes a first end portion <NUM> and a second end portion <NUM>.

In a nonlimiting example, first outer diameter OD1 is greater than first inner diameter ID1, second outer diameter OD2 is closely matched to third inner diameter ID3, and third outer diameter OD3 is greater than the first outer diameter OD1, second outer diameter OD2, and second inner diameter ID2. At this point, it should be understood that the term "closely matched" is used to describe a clearance that exists between OD2 and ID3. The clearance allows valve member <NUM> to shift within valve chamber <NUM> while substantially preventing fluid from leaking past second section <NUM>.

In accordance with a non-limiting example, first end portion <NUM> is shown as being directly connected to first section <NUM> and second end portion <NUM> is shown as being directly connected to third section <NUM>. It should however be understood that first section <NUM> may be joined to first end portion <NUM> through a first intermediate portion (not shown) and third section <NUM> may be connected to a second end portion <NUM> through a second intermediate portion (also not shown). In a non-limiting example, first section <NUM> includes an axially facing surface portion <NUM> and third section <NUM> includes a first axially facing surface section <NUM> and a second, opposing, axially facing surface section <NUM>. In a non-limiting example, axially facing surface portion <NUM> selectively engages first sealing surface <NUM>. A spring <NUM> is anchored in fifth chamber portion <NUM> and coupled to second axially facing surface section <NUM>. Second axially facing surface section <NUM> selectively engages sealing surface section <NUM> when in the open position.

In one non-limiting example, valve chamber <NUM> may be a single unitary member or, in another non-limiting example, valve chamber <NUM> may be formed of two or more sections to promote installation of valve member <NUM>. In a non-limiting example, valve chamber <NUM> may include a first chamber section <NUM> that includes first chamber portion <NUM>, second chamber portion <NUM>, third chamber portion <NUM>, and part (not separately labeled) of fourth chamber portion <NUM>. Valve chamber <NUM> may also include a second chamber section <NUM> that includes a second part (also not separately labeled) of fourth chamber portion <NUM> and fifth chamber portion <NUM>. First chamber section <NUM> may be detachably connected to second chamber section <NUM> through, for example, a threaded connection <NUM>. In a non-limiting example, valve member <NUM> may be formed from a single unitary piece or, as shown in <FIG> may includes a joint <NUM> connecting third section <NUM> with second section <NUM>.

In a non-limiting example, pressure actuated switching valve <NUM> is a "snap-action" valve. That is, when exposed to a selected fluid pressure, valve member <NUM> substantially instantaneously transitions from a closed position (<FIG>) to an open position (<FIG>) with virtually no time spent in and intermediate position (<FIG>) i.e., a position in which valve member <NUM> is between the open and closed positions as shown in <FIG>. When the selected fluid pressure is removed or lowered, valve member <NUM> substantially instantaneously transitions from the open position to the closed position. The "snap action" is achieved by allowing pressure in first chamber <NUM> to act on a series of staggered areas (Area_ID1, Area_ID2, Area_ID3) in a manner such that valve member <NUM> transitions from fully closed to fully open at effectively a single pressure.

In a non-limiting example, supply fluid from upstream engine <NUM> enters inlet portion <NUM> and acts on axially facing surface portion <NUM> to start valve member <NUM> moving towards the right. After the valve member <NUM> has lifted off of sealing surface <NUM>, it very briefly resides in the intermediate position in <FIG>. In this position, clearance at ID3 is sized in relation to the leakages in member and a curtain area (not separately labeled) between face <NUM> and face <NUM>. The clearance at ID3 is significantly lower than the clearance at the curtain area. Thus, the pressure at outlet <NUM> will be equal to the pressure at inlet <NUM>. This pressure acting over the area prescribed by ID3 gives a positive force margin to ensure valve continues slewing through the mid stroke or intermediate position.

As valve member <NUM> approaches fully open position as shown in <FIG>, second axially facing surface section <NUM> seats upon sealing surface section <NUM> and provides sealing between high pressures from inlet <NUM> and ambient pressure in fifth chamber <NUM>. Once valve member <NUM> is sealed on sealing surface section <NUM>, pressure at inlet <NUM> may expand through first, second, third, and fourth chambers <NUM>, <NUM>, <NUM>, and <NUM> and provide a pressure load against first axially facing surface section <NUM> that keeps valve seated on sealing surface section <NUM>.

When supply fluid pressure drops below a selected value, spring <NUM> and pressure in fifth chamber portion <NUM> act upon second axially facing surface to substantially instantaneously shift valve member <NUM> back to the closed position. The substantially instantaneously movement is achieved by forming OD3 of third section <NUM> to be larger than OD1 of first section <NUM> such that a force balance pressure of valve member <NUM> is the same in each of the three positions (closed, intermediate, and open).

In a non-limiting example, loading of spring <NUM> at the closed position, the intermediate position, and the open position is offset by an increased inner diameters ID2 and ID3. In a non-limiting example, <MAT> wherein spring load is defined as the load applied by spring <NUM> to valve member <NUM> in each of the open position, the intermediate position, and the open position. This constant value of spring load divided by area provides a single pressure at which the valve translates between all three positions, in both the opening and closing directions.

With this arrangement, dwell time, or the amount of time valve member <NUM> is in the intermediate position, regardless of direction is minimized such that pressure actuated switching valve includes a low hysteresis. With the low hysteresis, undesiraed leakage from the inlet to the outlet is reduced so as to increase control responses and substantially eliminate control variances.

Claim 1:
A pressure actuated switching valve comprising:
a valve chamber (<NUM>), wherein the valve chamber (<NUM>) includes
a first chamber portion (<NUM>) defining an inlet, the first chamber portion (<NUM>) having a first inner diameter (ID1);
a second chamber portion (<NUM>) defining an outlet, the second chamber portion (<NUM>) having a second inner diameter (ID2) that is greater than the first inner diameter;
a first sealing surface (<NUM>) defined between the first chamber portion (<NUM>)
and the second chamber portion (<NUM>),
a third chamber portion (<NUM>) having a third inner diameter (ID3) that is greater than the first inner diameter;
a fourth chamber portion (<NUM>) having a fourth inner diameter (ID4) that is greater than first inner diameter, and
a fifth chamber portion (<NUM>);
a second sealing surface (<NUM>) defined at an interface of the fourth chamber portion (<NUM>) and the fifth chamber portion (<NUM>); and
a valve member (<NUM>) slidingly arranged in the valve chamber (<NUM>), wherein the valve member includes
a first section (<NUM>) arranged in the second chamber portion (<NUM>), the first section having a first outer diameter (OD1) that is greater than the first inner diameter and being configured to selectively engage the first sealing surface;
a second section (<NUM>) arranged in the third chamber portion (<NUM>), the second section having a second outer diameter (OD2) that is closely matched to the third inner diameter (ID3), and
a third section (<NUM>) arranged in the fourth chamber portion (<NUM>), the third section having a third outer diameter (OD3) that is greater than the first outer diameter, the second outer diameter, and the second inner diameter, and being configured to selectively engage the second sealing surface.