Metering valve

A metering valve assembly includes a metering valve sleeve and a metering valve spool. The metering valve sleeve includes an inlet window set and an outlet window set with a first outlet window having a first logarithmic contour and a second outlet window having a second logarithmic contour. A ratio of an inner width of the first outlet window to an inner length of the first outlet window is between 1.48 and 1.52. A ratio of an inner width of the second outlet window to an inner length of the second outlet window is between 2.21 and 2.29. The metering valve spool includes first, second, and third cylindrical portions. The metering valve spool is configured to move bi-directionally along a longitudinal axis of the metering valve sleeve and control fluid flow between the inlet window set and the outlet window set relative to the first, second, and third cylindrical portions.

BACKGROUND OF THE INVENTION

The present invention is related to fuel flow control, and more specifically to a metering valve.

Fuel flow control in systems such as gas turbines includes controlling and maintaining pressures within a fuel control housing of a fuel control. To control and maintain pressures within the fuel control housing, often the fuel flow is increased and decreased as well as diverted via a combination of control valves. A displacement pump pressurizes fuel prior to its metering and subsequent delivery to an engine. The displacement pump is typically sized to ensure an excess flow capacity at all possible operating conditions. The output of the pump is delivered to a fuel metering valve which, in conjunction with a bypassing, pressure regulating valve (PRV), meters the rate of fuel burn flow to the engine. Proper control of a fuel system is based on the consistent operation of all valves within the fuel system. Without consistent valve operation, the fuel system may become unpredictable.

BRIEF DESCRIPTION OF THE INVENTION

Exemplary embodiments include a metering valve assembly that includes a metering valve sleeve and a metering valve spool. The metering valve sleeve includes an inlet window set and an outlet window set. The outlet window set includes a first outlet window having a first logarithmic contour and a second outlet window having a second logarithmic contour. A ratio of an inner width of the first outlet window to an inner length of the first outlet window is between 1.48 and 1.52. A ratio of an inner width of the second outlet window to an inner length of the second outlet window is between 2.21 and 2.29. The metering valve spool includes a first cylindrical portion, a second cylindrical portion, and a third cylindrical portion formed between the first and second cylindrical portions. The metering valve spool is configured to move bi-directionally along a longitudinal axis of the metering valve sleeve and control fluid flow between the inlet window set and the outlet window set relative to the first, second, and third cylindrical portions.

Additional exemplary embodiments include a fuel control that includes a pressure regulating valve section configured to control a metered pressure of fuel and a metering valve section configured to meter a fuel burn flow at the metered pressure. The metering valve section includes a metering valve assembly with a metering valve sleeve and a metering valve spool. The metering valve sleeve includes an inlet window set and an outlet window set. The outlet window set includes a first outlet window having a first logarithmic contour and a second outlet window having a second logarithmic contour. A ratio of an inner width of the first outlet window to an inner length of the first outlet window is between 1.48 and 1.52. A ratio of an inner width of the second outlet window to an inner length of the second outlet window is between 2.21 and 2.29. The metering valve spool includes a first cylindrical portion, a second cylindrical portion, and a third cylindrical portion formed between the first and second cylindrical portions. The metering valve spool is configured to move bi-directionally along a longitudinal axis of the metering valve sleeve and control the fuel burn flow between the inlet window set and the outlet window set relative to the first, second, and third cylindrical portions.

Further exemplary embodiments include a method of installing a metering valve assembly in a fuel control. The method includes inserting a metering valve sleeve into a metering valve section of a fuel control housing. The metering valve sleeve includes an inlet window set and an outlet window set. The outlet window set includes a first outlet window having a first logarithmic contour and a second outlet window having a second logarithmic contour. A ratio of an inner width of the first outlet window to an inner length of the first outlet window is between 1.48 and 1.52. A ratio of an inner width of the second outlet window to an inner length of the second outlet window is between 2.21 and 2.29. A metering valve spool is arranged within the metering valve sleeve. The metering valve spool includes a first cylindrical portion, a second cylindrical portion, and a third cylindrical portion formed between the first and second cylindrical portions. The first cylindrical portion and the second cylindrical portion have a substantially equal first diameter. The third cylindrical portion has a second diameter. A ratio of the first diameter to the second diameter is between 2.52 and 2.63. The metering valve spool is arranged to establish a diametral clearance of 0.0003 and 0.0006 inches (0.000762-0.001524 cm) between an inner diameter of the metering valve sleeve and the first diameter.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1schematically illustrates a perspective view of a fuel control housing portion100of a fuel control102for regulating fuel flow for systems such as aircraft gas turbine engines. In one embodiment, the fuel control housing portion100includes a pressure regulating valve section105, a metering valve section110, a containment housing section115that is generally adjacent to the metering valve section110, and a servo minimum pressure valve section120. Other valves, control and feedback features (not depicted) may also be included in the fuel control housing portion100or in another portion (not depicted) of the fuel control102. Fuel flowing into the fuel control housing portion100is pressurized in a pump section125. Pressurized flow is metered in metering valve section110before being output as a fuel burn flow at a metered pressure. The pressure regulating valve section105sets and controls the metered pressure of the metering valve section110. The fuel control102can also provide fluid pressure for actuators (not depicted), where the servo minimum pressure valve section120establishes a minimum pressure and discharges excess flow to the pressure regulating valve section105.

FIG. 2schematically illustrates a cross-sectional view of the metering valve section110and the containment housing section115ofFIG. 1including a metering valve assembly150according to an embodiment. The metering valve assembly150includes a metering valve spool200arranged within a metering valve sleeve210. The metering valve spool200includes a first cylindrical portion201and a second cylindrical portion202. A third cylindrical portion203is formed between of the first and second cylindrical portions201,202. A differential in diameter between the first and second cylindrical portions201,202and the third cylindrical portion203forms a space213when the metering valve spool200and the metering valve sleeve210are concentrically arranged.

In one embodiment, the metering valve sleeve210includes an inlet window set211and an outlet window set212. The outlet window set212includes a first outlet window212aand a second outlet window212b. When the metering valve spool200is positioned within the metering valve sleeve210such that at least a portion of the space213aligns with the inlet and outlet window sets211and212, a fluid, such as fuel, can flow at an inlet pressure P1at the inlet window set211through the space213and out of the outlet window set212at a metered pressure P2. The metering valve spool200can move bi-directionally along longitudinal axis250as indicated by arrows251,252to control fuel burn flow between the inlet window set211and the outlet window set212. Movement of the metering valve spool200within the metering valve sleeve210in the direction of arrow251may be limited by a limiting lip205of the metering valve spool200and a limiting lip225of the metering valve sleeve210. Movement of the metering valve spool200within the metering valve sleeve210in the direction of arrow252along the longitudinal axis250may be limited by the containment housing300. The metering valve sleeve210remains fixed with respect to the metering valve section110.

The containment housing section115includes a containment housing300configured to retain a linear variable differential transformer (LVDT)215in a fixed position with respect to the fuel control housing portion100. The LVDT215provides position feedback for position control of the metering valve spool200. A translating member218extends from the LVDT215and couples to an end222of the metering valve spool200such that axial position and movement of the metering valve spool200can be detected by the LVDT215.

FIG. 3illustrates a perspective view of the metering valve spool200in isolation and the metering valve sleeve210in isolation.FIG. 3further illustrates a perspective view of the metering valve spool200and the metering valve sleeve210in a concentric arrangement. As depicted inFIG. 3, each of the six inlet windows in the inlet window set211has a substantially rectangular shape. The outlet windows212a,212bare offset by about 180 degrees relative to each other and have different shapes. In one embodiment, the shapes of the outlet windows212a,212bare both defined by logarithmic contours. The logarithmic contours of the outlet windows212a,212bmay be designed based on a desired flow and pressure in the metering valve section110ofFIG. 2, and various axial lengths and diameters of the metering valve spool200and the metering valve sleeve210. The logarithmic contours of the outlet windows212a,212bprovide tightly controlled inlet and outlet flow paths between the inlet window set211and the outlet windows212a,212b. In an embodiment, the inlet window set211is sized to reduce pressure drops within the metering valve assembly150.

FIG. 4depicts additional details of the metering valve spool200in a cross-sectional view according to an embodiment. The metering valve spool200has a length L1from the limiting lip205to a spool end230of about 3.325 inches (8.45 cm), a length L2from the limiting lip205to a break edge232of the first cylindrical portion201of about 0.94 inches (2.39 cm), and a length L3from the limiting lip205to a break edge234of the second cylindrical portion202of about 2.011 inches (5.11 cm). A ratio of length L1to length L2is between 3.51 and 3.56. A ratio of length L1to length L3is between 1.65 and 1.66.

The first cylindrical portion201includes a first grooved section240. The second cylindrical portion202includes a second grooved section242. In an embodiment, the first grooved section240is a length L4of about 0.51 inches (1.30 cm) from the limiting lip205and includes eight grooves spanning an axial length L5of about 0.35 inches (0.89 cm). In an embodiment, the second grooved section242is a length L6of about 2.50 inches (6.35 cm) from the limiting lip205and includes four grooves spanning an axial length L7of about 0.15 inches (0.38 cm).

A first radius R1transitions between the first cylindrical portion201and the third cylindrical portion203. A second radius R2transitions between the second cylindrical portion202and the third cylindrical portion203. In an embodiment, first radius R1and second radius R2are substantially equal and have a value of about 0.125 inches (0.318 cm). The first cylindrical portion201and the second cylindrical portion202have a substantially equal outer diameter D1of at least 0.707 inches (1.80 cm). The third cylindrical portion203has an outer diameter D2of about 0.275 inches (0.70 cm). The limiting lip205has an outer diameter D3of about 0.995 inches (2.53 cm). A ratio of outer diameters D1to D2is between 2.52 and 2.63. A ratio of outer diameter D3to D1is between 1.40 and 1.41.

FIG. 5depicts further details of the metering valve sleeve210in a cross-sectional view according to an embodiment. The metering valve sleeve210has an internal diameter D4of a maximum of 0.71 inches (1.80 cm). A diametral clearance of 0.0003-0.0006 inches (0.000762-0.001524 cm) is maintained between the internal diameter D4of the metering valve sleeve210and the outer diameter D1of the metering valve spool200ofFIG. 4for each matched set of the metering valve spool200and the metering valve sleeve210. An outer diameter D5of the metering valve sleeve210is about 0.9885 inches (2.51 cm). The limiting lip225of the metering valve sleeve210has a diameter D6of about 1.21 inches (3.07 cm).

In an embodiment, the metering valve sleeve210has a length L8of about 3.234 inches (8.21 cm) from the limiting lip225to a metering valve sleeve end260. The inlet window set211is located at a length L9of about 0.898 inches (2.28 cm) from the limiting lip225. Each of the six inlet windows of the inlet window set211has a length L10of about 0.203 inches (0.516 cm) and a width W1of about 0.300 inches (0.762 cm). An outer edge262of the first outlet window212ais located at a length L11of about 1.59 inches (4.04 cm) from the limiting lip225. The first outlet window212ahas an outer length L12of about 0.548 inches (1.39 cm) and an inner length L16of about 0.36 inches (0.914 cm), where a contour radius R3of about 0.094 inches (0.239 cm) provides a transition from the outer edge262to an inner edge266of the first outlet window212a. The inner edge266is radially closer to the longitudinal axis250than the outer edge262. An outer edge264of the second outlet window212bis located at a length L13of about 1.71 inches (4.34 cm) from the limiting lip225. The second outlet window212bhas an outer length L14of about 0.428 inches (1.09 cm) and an inner length L17of about 0.24 inches (0.610 cm), where a contour radius R4of about 0.094 inches (0.239 cm) provides a transition from the outer edge264to an inner edge268of the second outlet window212b. The inner edge268is radially closer to the longitudinal axis250than the outer edge264. The metering valve sleeve210also includes a pair of apertures270located at a length L15of about 2.666 inches (6.77 cm) from the limiting lip225. Each of the apertures270is offset by about 180 degrees relative to each other and has a diameter D7of about 0.033 inches (0.084 cm).

A ratio of length L8to length L9is between 3.57 and 3.63. A ratio of length L8to length L11is between 2.03 and 2.04. A ratio of length L8to length L13is between 1.88 and 1.90. A ratio of width W1to length L10is between 1.43 and 1.53. A ratio of inner length L16to length L10is between 1.73 and 1.82. A ratio of inner length L17to length L10is between 1.15 and 1.22. A ratio of outer length L12to outer length L14is between 1.15 and 1.42.

FIG. 6schematically illustrates a top view of the first outlet window212aof the metering valve sleeve210, andFIG. 7schematically illustrates a top view of the second outlet window212bof the metering valve sleeve210according to an embodiment. The first outlet window212aincludes a neck portion272having a notch274above an axis A, where the first outlet window212ais substantially symmetric about axis A excluding notch274. The first outlet window212aalso includes a body portion276. Radius R5defines curvature of the neck portion272. Radii R6and R7define curvature of the body portion276. Radius R5is about 0.01 inches (0.0254 cm). Radius R6is about 0.03 inches (0.0762 cm). Radius R7is about 0.05 inches (0.127 cm).

The second outlet window212bincludes a body portion278and a neck portion280that is substantially symmetric about an axis A′. Radius R8defines curvature of the neck portion280and is about 0.01 inches (0.0254 cm). In an embodiment, the body portion276of the first outlet window212ais substantially equal to the body portion278of the second outlet window212b, as can be seen in greater detail in Table 1. A first logarithmic contour defining points of the first outlet window212ais provided in Table 1, for X values along axis A, Y1 values above axis A, and Y3 values below axis A. Table 1 also includes a second logarithmic contour defining points of the second outlet window212bfor X values along axis A′ and Y2 values about axis A′. Table 2 presents the data of Table 1 in centimeters rather than inches. It will be understood that a manufacturing tolerance can be applied to the values in Tables 1 and 2, as well as for other values described herein. From Tables 1 and 2 andFIGS. 6 and 7, it can be seen that the first outlet window212ahas an inner width W2of about 0.54 inches (1.37 cm) which is substantially equivalent to an inner width W3of the second outlet window212b. A ratio of inner width W2to inner length L16is between 1.48 and 1.52. A ratio of inner width W3to inner length L17is between 2.21 and 2.29. A ratio of inner width W2to width W1is between 1.76 and 1.84.

TABLE 1Outlet Window Coordinates in InchesXY1Y2Y300000.01350.01350.0680.01350.01350.120.040500.01350.120.01350.01350.01350.1350.0190.0190.0190.150.0230.0230.0230.170.0390.0390.0390.190.0610.0610.0610.210.0860.0860.0860.230.1290.1290.1290.250.1880.1880.1880.2660.2340.2340.2340.2770.270.270.270.320.270.270.270.360.270.270.27

A method of installing the metering valve assembly150in fuel control102is described herein with reference toFIGS. 1-7. The metering valve sleeve210is inserted into the metering valve section110of the fuel control housing portion100. As previously described, the metering valve sleeve210includes inlet window set211and outlet window set212. The outlet window set includes first outlet window212ahaving a first logarithmic contour as defined in detail in Tables 1 and 2. The second outlet window212bhas a second logarithmic contour as defined in detail in Tables 1 and 2. The metering valve spool200is arranged within the metering valve sleeve210. The metering valve spool200includes first, second, and third cylindrical portions201,202, and203. The first cylindrical portion201and the second cylindrical portion202have a substantially equal first diameter D1, and the third cylindrical portion203has a second diameter D2. The metering valve spool200is arranged to establish a diametral clearance of 0.0003 and 0.0006 inches (0.000762-0.001524 cm) between inner diameter D4of the metering valve sleeve210and the first diameter D1. LVDT215is coupled to the metering valve spool200and retained by containment housing300in the containment housing section115.