GB2521721A - Rotary metering valve assembly and method of modifying contact surface for reducing gauge wringing - Google Patents

Abstract

A rotary metering valve assembly 10 includes a stationary body plate 12 having a first contact surface, and a valve plate 16 having a second contact surface disposed in contact with the first contact surface of the stationary body plate. The valve plate is configured to rotate relative to the stationary body plate. At least one of the first contact surface and the second contact surface comprises a surface flatness of less than about 2.4 µm and a surface roughness of at least about 0.2 µm. The surface roughness ranges from 0.2 microns to 0.8 microns. The valve may be a portion of a fuel metering device of a gas turbine engine of an aircraft. Also provided is a method of modifying a contact surface of a rotary metering valve for reducing gauge wringing. The method comprises smoothing a contact surface of a rotary valve, then roughening said surface.

Description

ROTARY METhRING VALVE. ASSEMBLY AND yjFTIj()) OF MODIFYING (MN tACT SURFACE FOR RED' K iNC GAUGE WRINGING

BACKGROUND OF THE INVENTION

[00011 The embodiments herein relate to rotaiy metering valve assemblies, as wcIl as a method of modiMnu a contact surLce ot the iotasy metering vive ase aNy for reducing gauge wringing.

[00021 Rotary metering valve assemblies may he used in a variety of applications that require the regulation of a fluid. A fhei metering valve assembly is an example of such an aunlication. Among other components, the assembly includes e vals e plate and a valvc body I he a' t plate a angular lv movable reIati c to tho a1vc both under the control ot fdi cxampe, a sur!dhk motor the motor movo3 plate het'a ceo p,citwns in which metering oufkc' of the atw pUtt ai d als e body dictate an open flow area. The open flow area is based on relative location of the metering onikes which changts with rotatron of the baRe plate Comaet betu con the dye pUnt and t e a1'e body impose hydra the ml lnctional for,.c' and the assembly is. thus, designed to avoid "sticking" therebetween.

BRIEF DESCRiPTION OF THE INVENTION

0003i According to one embodiment, a. rolary metering vakte assembly includes a. stationary body plate having a first contact surface. Also me!uded is a valve plate having a econd conta.t surface dlspobd in onraet with the first contact surtace ot the static nary iy dy plate wherein the alvc plate w configured to rotS rdative to the stationary body plate. least one of the first contact surface and the second ontaet surface comprises a,rrLce flatness ot less tlu,n about 2 4 uncrorne&rs (93 MitI) and a surface roughness of at least about 0.2 micrometers Qirn) (about 8 tdn).

[0004]. According to another er,hodiment, a method of modifying a contact surface of a rotary metering valve assembly for reducing, gauge wringing is provided

I

The method includes smoothening a contact surface of the rotary valve assembly to a desired surf cc fiatn.ss The method Jw mdudes ioughenng thu contact stuface to a surthee roughness of at least about (12 rn (about S tin), The method flurther includes maintaining the desired surfiice flatness while toughening the contact surface.

BRIEF DESCRIPTION OF THE DRAWINGS

[00051 The subject matter whmh is regarded as the invention is particularly poimec out and d stinutly claimed in the kuns at the conek \lOfl of the spucific thou The foregoing and other features and advantages of the invention are apparent from the Ibilowing detailed description taken in coniunction with the accompanying drawings in which: [00061 PiG. 1 is a partial schematic illustration of a valve plate and a valve body of a rotary metering valve assembly; [00071 PEG. 2 is a schematic iliastration of a first plate and a second plate having a fluid flowing therebetween; [0008]. FIG. 3 illustrates a contact surface of the valve body having a first surface roughness; [0009] FIG. 4 illustrates the contact surthee of the valve body having a second sw±iice roughness after being subjected to a surface roughening process; and fOol 0] FIG 5 is a flov< hagrarn ii ntrating a method of modihing thu contact surface of the rotary metering valve assembly fbi reducing gauge wringing DETAIl PD DFSRIP I ION 01 tHE NYL MI ION [0011] Refening to FIG. 1, a portion ePa rotary metering valve assembly lOis ShO\kn ihe roarv mctwng \the asunb1y 10 rn he employed in coiiu cion with umoons appi cations En particilat the embodiments of the rotAry metering alv assembly 10 described herein may he part of any lubricated application with low to moderate loading arid. where fiat, smooth pLates are in frictional contact and move relative to each other with low velocity, such as a rotary plate metering valve anphcation. in one embodiment, the rotary metering valve assembly 10 is a.

component of i luel rneenng umI fbi a gas turbine ngne located on an aneiaft 10012] The rotary metering valve assembly 10 includes a stationary body plate 12 that includes at least one metering orifice 14 QIGS. 3 and 4). A valve plate 16 ahuts s surta ot the 4attonay body plate 12 and i arigulat ft movable by a drne arrangement to vary the degee by which the valve plate 16 obscures the at least one metuing onhc 14 In certain embodin'ems the valve plate 16 also ii Lhidcs a metering orifice. Rotation of the valve plate 16 controls a flow area upon which a fluid, such as fudi, can flow. Due to the shape of the metering orifice(s), the size of the fiot area sJHC is a function of angle from zero to tall stroke Ihe torque required.o opert and elost the val vC may he epie',ed \vth the following equation fbi a situation relating to relative movement between circular plates, as shown in FIG. 2; iorq*ire Vt where w is the angular velocity; i is the absolute viscosity; R the radius of the surface area of contact; and h is the distance between the plates. Based on the sigmth a -ice of the urfaee area (i t. burtn po ci) a ieduetion of the surface area u, desirable, Additionally, as the surface finish of the contact surfaces is finer, the plates becoma closer togetner, thereby incre4su g the equircd torque As showu it. RU 1, the v al e plate 16 rota es relative o the sationai y body plate 12 in a rut ction 22 and a fluid velocity profile is referenced. with r ineral 24.

COOl 3]The stationary body plate 12 and the valve plate 16 may be formed. of various materials. In one embodiment, the stationary body plate 12 is formed of a hard stee-based alloy, such as Greek AscoloyTM 4250 HRC) and the valve plaCe 16 is formed of a nitride steeL-based alloy. The valve plate 16 is assembled with a light spring oad wiuch keeps it in contact uith tnc stationary buoy plate 12 \ii dd:onaI load is impocc during operaLon ot the rotary metering Vdlk c assembly Ri due to a pressure diitrentiai, thereby further loading the valve plate 16 against the stationary valve plate 12..

00l4j As noted above, the valve plate 16 abuts a surface of the stationary body plate 12 Specifically, the stationary body plate 12 induces a tirt contact surface 18 that is disposed in ontset with a see, ml contact surtace 20 ci die valve plate 15.

[Old I With the abcs e tor tic cquatn n mmd, the embodiment-herein nutigate a ige i'r ngmg between the stanon&y body plate I aic the valve plate in, sshde adhering to flatness requirements of the plates. Low flatness is required. to minimize kaKage and weat ow £oughne's js typically asoeiated s;tth the los flatncss, but the embodiments hch n mcreae roughening:c mitigate gauge wringing, while cull meeting acceptable ievdts of leakage and wear. This is achieved by roughening the first cc tact sutfacc 18.nd/or the second contact surtacc 20 lii one embediment only the first contact surface IS is roui4ened to an enhanced surface roughness.

Fiowever, it is contemplated that the second contact surfuce 20 may he additionally rougnened in the alernatn e to or in combination wan, the that contact surface 18 [0(16] The first contact surface 18 and/or the second contact surface 20 comprise a surface flatness of lecs than or cc cal to about 2 4 pm (about 93 un) anci a surface roughness of greater than or equal to about 02 m (about S pin. In one embodiment, the surface roughness ranges from about (1.2 Inn ábout S pin) to about ftS pm Qihout $2 pin). In yet another embodiment, the surface roughness is about ft6 m (about 24 RJ [001 7j A method of nioctdying i comact suiface of a rotar metent g salve assembly fur reducing gauge wringing 100 is also provided, as illustrated in FIG. S and with reference to FIGS. i 4. The rotary metering valve assembly 10 and, more parthnilarlv, the contact surface(s) of the stationary body plate 12 and the valve plate 16, have been previously described and specific structural components need not be described in I rther detail.

[00181 The method of modifying a contact surface 100 includes smoothening 102 a contact surface of the rotary valve assembly 10 to a desired surface flatness. As discussed abc e the dc\lrcd surface flatness typically ks' than ci about 2 1 im (about 93 pin). Any suitable machining process may be employed to achieve the desired surtaec flaness In one emboduncu a lapp ng process i employed HG illutrates the fast cot tact surface IS with a flu t roughness [00 i subcequent1. the contact suflc s roughened to a surface ucrughnoss 04 ipon comç4e ion, thu. sarfec iou. ghness of the contact surface s typically greater than abuot 0 2 cm (8 nn In one embodiment, the suufacc rougrL-iu.ss rangc from about 02 inn to about 0.8 p.m (about 8 pin to about 32 pin). n yet another embodiment, the surface roughness is about 0.6 gm (about 24 pin). The enhanced roughness is shown as a second roughness in FIG. 4. As with achieving the desired suufacc flatness any suitable machining pro...es n as' he enp1oycu to a.hic\ c the desired surface roughness.. In one embodiment, au abrasive paper is used to roughen the contact surface, however, numerous other processes may be employed, such as Grit blasting or chemical etching. During roughening 104 of the contact surface, the desired surface flatness is maintained 1 06.

002'fl Advantageously, mequirements fou opcration of the rohcry meteung aIve assembly 10 dunng svsLrn lailurc. eondituon may be met SpeciE uihy, the enbodimc'nts dc,cnbcd h.sein dliow the salv ssenthly.o operate at higher p-essures while maintaining consistent friction behavior. By providing a contact surface with a minimum required suthee roughness that is suitable for the particular application, the advantages described above are accomplished, [00211 While the invention has been described in detail in connection with only a inmted number of embodiments, it s'iould be reedily undeustood that ñc inve.ntinn is not limited to such disclosed embodiments. Rather, the invention can he modrfied to incorporate any nuniher of variations, alterations, substitutions or equn'aent arrangements not heretofore desnbed, but which are on1mensaratc with the scope of the invention as defined by the claims. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the inention may rncude only orne of the deacrbcd embodiments Acordm]y, the invention is not to be seen as limited by the foregoing description. but is only limited by the scope of the appended claims.