GB2109469A - Fuel distribution valve flow trimming and locking means - Google Patents

Abstract

A fuel distribution system (Fig. 1) includes a fuel distribution valve (10) having a single fuel inlet (12) and a plurality of fuel discharge ports (24), each connected by an individual fuel manifold (44) to the inlet of an engine fuel injector. The valve (10) has identical fuel metering holes (20,22) for distributing meter fuel flow to each manifold and injector. An adjustable flow control plug (40) located downstream of the metering holes is accessible during fuel flow through the system to adjust for system inequalities so as to balance the system during operation. <IMAGE>

Description

SPECIFICATION Fuei distribution valve flow trimming and locking means This invention relates to an engine fuel flow distribution systenl, and for example to such a system wherein a multiple outlet fuel distribution valve provides equal fuel flow to each of a piurality of engine fuel injectors.

Engine fuel flow distriburion systems are knows which include a fuel distribution valve assembly having a single fuel inlet port and multiple fuel discharge ports. An individual fuel manifold conduit separately supplies fuel from each discharge port to a fuel injector assembly such as a fuel nozzle having an inlet port and a spray tip outlet for injecting fuel into the engine combustor, whether a variable voiume cylinder or a fixed volume chamber.

To produce controlled fuel distribution throughout the system, heretofore the fuel flow versus fuel pressure characteristics of each component of the system is determined. Desirably, these characteristics are held within a range so that components of the system can be interchanged by like components without affecting the controlled distribution of system fuel flow. However, each system component, arid replacement parts for each component, have slightly different fuel flow versus fuel pressure characteristics. In order to calibrate the system for intsrchangeability of injector parts, normal practice has been to place a trimming orifice in the inlet of each fuel injector.This orifice is removable and size adjustable to adjust the fuel versus fuel pressure from the inlet of the distribution valve to the spray tip of each nozzle. All the injectors in the system can be held to close flow limits by use of such trim orifices wiich can be located in the inlet of the injector.

The seme procedure has bean used to adjust individual fuel injectors to give closely held flow !imits for interchangeability. In such cases the trimming orifice is normally located in the inlet end of the manifold assembly to provide manifolds with like fuel versus pressure characteristics.

Because of dimensional variations in the system, each individual fuel maniFold car. have varying lengths and shape (bends, turns and the like) between its connection to the outlet of the distributor valve and its connection to the inlet of the fuel injector. In such cases it can be impractical to hold all manifolds to the same characteristics. In such cases, manifolds of a given length and shape are held to close flow limits by use of trimming orifices to provide interchangeability of such manifolds without affecting total system distribution.

The fuel distribution valve in such system desirably has identical fuel metering slots or holes for distributing metered fuel to each system manifold and injector. Such slots or holes are easire to manufacture, but they do require some form of flow adjustment downstream of the metering to adjust for vaive inequalities, such as internal valve manifolding of variable length, size or shape or like differences in internal valve passages because of manufacturing variations. To test fuel distribution from the distribution valve assembly accurately it is necessary to direct fuel though the complete system or its analog to take into account intersystem crnss-leakage.

Fuel flow versus fuel pressure variations within the valve are presently adjusted by use of replaceable trimming orifices like those used in association with each manifold and each nozzle.

Adjustment of fuel characteristic variations within the valve is more difficult when total system flow occurs, since adjustments made in one of the internal valve passages will affect distribution through the other internal valve passages. As a result, testing and adjusting of distribution valves is a long, tedious procedure that requires system shut-down arid rnpet;r've assembly and trial and error replacement of trimming orifices in the system components before a fuel distribution valve is trimmecl for use in a fuel supply system.

An object of the invention is to provide an improved, externally adjustable fuel flow versus fuel pressure characteristics flow trimming adjustment means in each of a plurality of passages in a fuel distribution valve for an engine fuel system.

Another object of the invention is to provide an improved fuel flow versus fuel pressure flow trimming adjustment means in a fuel distribution valve downstream from fuel metering components of the valve which are externally adjustable to produce desired fuel distribution from the valve without removing it from the fuel system or a fuel system analog and without shutdown of total system fuel flow through the valve.

According to this invention there is provided a fuel flow distribution system having a distribution valve with a valve body including a single inlet and a plurality of discharge ports each connected to a manifold and each manifold being connected to a fuel injector, a fuel flow characteristic versus fuel pressure flow trim means for trimming fuel characteristics at each discharge port, the flow trim means including means forming a passage in the valve body, an axially movable plug inside the passage including an outboard end accessible from the exterior of the valve to shift the plug inside the passage, and means on the plug for sealing the passage and to vary the fuel flow area to each discharge port in accordance with the position of the plug within the passage whereby fuel flow characteristics versus fuel pressure characteristics adjustment can be made at each discharge port as total system fuel flow passes through the full system without disassembly of its component parts.

The invention will now be described by way of example, with reference to the drawings, in which: Figure 1 is a schematic view of a fuel system; Figure 2 is an enlarged, fragmentary section of a flow trimming adjustment means in the system of Figure 1: Figure 3 is a fragmentary section of a flow control valve including another embodiment of a flow trimming adjustment means; Figure 4 is an enlarged, section of the flow trimming adjustment means in the valve of Figure 3; Figure 5 is a view of a fuel distribution valve with a single metering edge which slides within a linear having a plurality of metering slots or holes and including another embodiment of the present invention; and Figure 6 is an enlarged view of the flow trimming means in the valve of Figure 5.

Referring to the drawings, Figure 1 shows a fuel supply system including a fuel distribution valve 10 having a single inlet 12 to receive fuel from a fuel controller 1 4. The valve 10 includes a pressure responsive valve element 1 6 which slides in a linear 18 to control fuel flow through ports or holes 20, 22 formed in the valve element 1 6 and liner 1 8. To simplify explanation, other details of the valve 10 are omitted.

Total system fuel flow from the inlet 1 2 is metered by sliding movement of the valve element 1 6. Such movement causes overlapping of holes 20, 22 to meter and distribute fuel to each of a plurality of discharge ports 24 formed at spaced points around a distribution head 26 formed on the valve body 28.

Fuel flow communication between each of the slots or holes 20, 22 and each discharge port 24 is through a lateral passage 30 in linear 1 8.

Distributor head 26 includes a separate passage 32 that is in line with passage 30. The horizontal passage 32 intersects a vertical bore 34 and a side bore 36 in distributor head 26. Side bore 36 extends through the outer surface of body 26 at tubular extensions 38. Several extensions 38 are formed at spaced, peripheral points therearound in line with each discharge port 24.

Each tubular extension 38 houses a flow trimming assembly 40 and lock 42.

As referred to above, manufacturing variations produce different flow characteristics in passages 20, 22, 30, 32 and discharge ports 24. The flow trimming assembly 40 is located downstream of the metering components in valve 10 and is operative separately to calibrate a plurality of flow paths in the valve while it is connected to downstream components of the fuel supply system. The downstream system includes a plurality of fuel manifolds 44, of which one is shown in Figure 1, with a removably adjustable orifice 46 in one end thereof. A fuel manifold 44 connects each discharge port 24 to one end of a fuel nozzle 48. Each nozzle 48 has a removably adjustable orifice 50 at its inlet The system components downstream of valve 10 can be pre-adjusted for like flow characteristics.However, once the system is connected together it is recognized that crosssystem leakage, head effect and variations in internal flow paths of the valve 10 can produce system inequalities.

Accordingly, the present construction includes features in each of the flow trimming assemblies to permit adjustment of fuel flow characteristics versus pressure characteristics of the system downstream of the metering components of the system which are formed by ports or holes 20, 22 in valve element 16 and liner 18, respectively.

More particularly, Figure 2, each flow trimming assembly 40 includes a plug 52 with a threaded outer surface 53 and with an inboard nose 54 at one end, and a skirt 56 formed at the opposite end. The plug 52 is axially positioned within a threaded portion 55 of bore 36 so that the nose 54 is positioned to block part of a flow path formed by the intersection 58 between vertical bore 34 and horizontal passage 32 (as viewed in Figure 2). Threaded adjustment of plug 52 axially of bore 36 will produce a variable adjustment of flow area to trim each flow passage.

The waist 60 of plug 52 includes an external shoulder 62 which receives an O-ring 64 that defines a first seal against leakage from bore 36. A tool socket 66 is formed internally of waist 60 and is accessible from the exterior of the valve 10. The socket 66 receives a tool for threadably positioning the plug 52 axially of bore 36. As the plug 52 is positioned, fuel flow continues and suitable instrumentation (not shown) will indicate when the adjusted flow area through each intersection produces a desired trim of fuel flow characteristics and pressure characteristics. The trim occurs as total system fuel flow passes through the single inlet 12, Figure 1.As each downstream branch is corrected, changes in each remaining branch is observed and any deviation from desired characteristics is readily adjusted by each of the flow trimming assemblies while ail the system components are in place and while the total system fuel flows through the system. Thus adjustment to produce flow characteristics versus pressure characteristics can be made continuously in each flow path and without a long and tedious trial-and-error procedure that requires system shutdown and disassembly and reconnection of components.

Once the system is adjusted to meet desired system distribution requirements, there is operated a lock 42 defined by a conical inner surface 68 on the outboard end of plug 52 and a wedge type ring 70 with a conical outer surface.

The ring 70, when inserted, Figure 2, will produce only a radially directed force on plug 52 which wedges the skirt 56 securely to the wall of bore 36. Interference between skirt 56 and the wall 10 of bore 36 will hold the plug 52 in its adjusted trim position when the ring 70 is seated against inner surface 68 of plug 52. The plug 52 has an internal thread 71 to receive a seating tool for pressing the ring 70 in place to lock the plug 52 in its adjusted position.

After adjustment and locking of plug 52, the ring 70 holds the outer surface 72 of skirt 56 tightly against the wall of bore 36. The outer surface 72 has a plurality of axially spaced, annular grooves 74 that define a second seal outboard of O-ring 64. Ring 70 includes a threaded bore 75 which has an internal diameter greater than the internal diameter of thread 71 to permit access of the seating tool. The threaded bore receives a tool for removing the ring 70 in order to change the adjustment of plug 52.

Another embodiment of the invention is illustrated in Figures 3 and 4 wherein a flow distribution valve body 76 is shown. It includes a single inlet passage 78 which communicates with the inside of a valve element 80. Metering ports or holes 82, 84 are formed in element 80 and the valve body 76 at a bore 86. The ports or holes 82, 84 define metering components upstream of and in communication with bores 88 in valve body 76 formed laterally of bore 86 from the outside surface of valve body 76. Each bore 88 intersects a discharge passage 90 leading to a discharge port 92. Each port 92 is connected to downstream fuel manifolds and fuel nozzles as described with reference to the embodiments of Figures 1 and 2.

In Figures 3 and 4, a flow trimming assembly 94 is located in each bore 88. Each assembly 94 includes an externally threaded plug 96 with a nose 98 adjustably positioned at the intersection 99 of passage 90 and bore 88 to vary adjustably the flow area therethrough. An outboard flanged head 102 of plug 96 is press fit in bore 88. Head 102 defines an inboard shoulder against which an O-ring seal 104 abuts to seal the bore 88. A tool socket 106 in the head 102 receives a tool for axially, threadably adjusting the assembly 94 in a threaded portion 95 of bore 88 to establish a desired fuel distribution, for example, equal distribution from all discharge ports, even though each discharge stream has varying conditions downstream of the discharge port.

The embodiment of Figures 5 and 6 shows a flow trimming assembly for trimming flow in a conventional, single edge flow distribution valve 110. The valve 110 includes a movable valve element 112 with a single edge 114 positioned axially of flow metering holes or ports 116 in a valve liner 11 8. Each hole 116 communicates with an outlet or discharge tube 1 20 which fits in a side passage 122 of the valve body 124. Each tube has a side bore 126 through which the nose 128 of a flow trimming assembly 130 extends.

Assembly 130, Figure 6, includes component parts like those found in assembly 94 in the embodiment of Figures 1 and.2 which are referenced in Figure 6 with like reference numerals primed. In this embodiment the assembly 1 30 is adjusted and locked in the same manner as in the embodiment of Figures 1 and 2.

The adjustment of nose 1 28 in the straight flow of fuel through tube 1 20 establishes the adjusted flow area control for adjustment of fuel flow characteristics and fuel pressure characteristics. It should be understood that each tube 1 20 is connected to downstream fuel manifold and nozzle components as shown in Figure 1.

In each of the above-described embodiments, it should be emphasized that along with compensation of normal system drop variations, the illustrated flow trimming assemblies also compensate for head effects produced by variations of the valve body position with respect to nozzle and manifold positions.

Claims (5)

1. A fuel flow distribution system having a distribution valve with a valve body including a single inlet and a plurality of discharge ports each connected to a manifold and each manifold being connected to a fuel injector, a fuel flow characteristic versus fuel pressure flow trim means for trimming fuel characteristics at each discharge port, the flow trim means including means forming a passage in the valve body, an axially movable plug inside the passage including an outboard end accessible from the exterior of the valve to shift the plug inside the passage, and means on the plug for sealing the passage and to vary the fuel flow area to each discharge port in accordance with the position of the plug within the passage whereby fuel flow characteristics versus fuel pressure characteristics adjustment can be made at each discharge port as total system fuel flow passes through the full system without disassembly of its component parts.

2. A system according to claim 1, wherein the outboard end includes a skirt and lock means engageable with the skirt to force it into engagement with the valve body so as to lock the plug in an axially adjusted position, the lock means being removable from the exterior of the valve.

3. A system according to claim 1, wherein the outboard end includes a skirt with outer grooves therein, the seal means includes an O-ring seal on the outer diameter of the plug and means deflecting the skirt radially outwardly against the walls of the passage to form a secondary seal.

4. A system according to any preceding claim wherein the plug has an exteriorly threaded surface thereon, the passage having a portion thereof internally threaded to threadably receive the plug for axially threaded adjustment within the passage to vary the fuel flow area.

5. A fuel flow distribution system constructed and arranged substantially as herein described and shown in the drawings.