US3700209A

US3700209A - Balanced pintle valve

Info

Publication number: US3700209A
Application number: US102570A
Authority: US
Inventors: Joe D Usry
Original assignee: E Systems Inc
Current assignee: Raytheon Co
Priority date: 1970-12-30
Filing date: 1970-12-30
Publication date: 1972-10-24
Anticipated expiration: 1989-10-24

Abstract

To minimize actuation power requirements in a metering flow control valve, forces generated on the metering pintle are statically and dynamically balanced. To reduce actuation power, the mechanization of the flow control valve must be an integrated concept that combines valve geometry and balancing techniques. The pintle in either a throttling valve or an injector valve is dynamically balanced by a plurality of passages formed in the pintle. These passages are arranged to be successively withdrawn into the upstream pressure to balance forces generated by a fluid flowing past the pintle. As each succeeding passage is exposed to the upstream pressure, the pressure in a compensating chamber increases to produce a force that tends to balance the force produced on the pintle by fluid flowing through the valve. With a generally conical shaped metering pintle, the passages are displaced both longitudinally along and radially around the pintle.

Description

United States Patent Usry [4 1 0a. 24, 1972 [54] BALANCED PINTLE VALVE 57 ABSTRACT Inventor; Y J Arlington, To minimize actuation power requirements in a meter- [73] Assignee; E System, Inc Dallas ing flow control valve, forces generated on the metering pintle are statically and dynamically balanced. To [221 Ned: 7 reduce actuation power, the mechanization of the flow 21 App]. 02,570 control valve must be an integrated concept that combines valve geometry and balancing techniques. The pintle in either a throttling valve or an injector valve is C(il dynamically balanced by a plurality of passages e fomled in e pintle These p g are arranged to [58] Field of Search ..251/282, 137/484.2, 484.4 be successively withdrawn into the upstream pressure to balance forces generated by a fluid flowing past the [56] References Clted pintle. As each succeeding passage is exposed to the ITE S S PATENTS upstream pressure, the pressure in a compensating chamber increases to produce a force that tends to 933,468 9/ 1909 Koenig ..251/282 X balance the force produced on the pintle by fl i 2,516,996 8/1950 Jensen ..251/282 X ing through the valve w a generally i l h d 2,843,351 7/1958 Griest ..251/282 X metering pintle, the passages are displaced both 3,601 ,l47 8/1971 Myers ..137/484.2

Primary Examiner--M. Cary Nelson Assistant ExamirierDavid R. Matthews Attorney-James D. Willborn and Richards,'Harris & Hubbard gitudinally along and radially around the pintle.

11 Claims, 9 Drawing Figures I42 I46 I L L I32 I34 m I g 158 i 1 I54 l [I08 I [,8 J Ill H0 H8 r= =nll2 I .9./ @5/ 1 V Q2 I L J 1/4 116 I16 H6 PATENTED um 241912 PINTLE FORCE LBS.

sum-32ers P l OOOp si IPO= o (5) 38 m l I l I I l 0.| 0.2 0.3 0.4

PINTLE STROKE-INCHES Fl 6. 2 I

' PI NTLE STROKE-INCHES F I G. '3

I I'NVENTQR 005 D. usm' ATTORNEYS PATENTEDH'BIMI 1912 3. 700.209

SHEET 3 [IF 3 INVENTOR JOE D. USRY ATTORNEYS BALANCED PINTLE VALVE This invention relates to a metering flow control valve, and more particularly to a statically and dynamically balanced pintle valve.

The balancing of a pintle valve usually consists of statically balancing the valve seat area with equal area pistons that oppose the pressure times area forces on the pintle plug. With such statically balanced valves, when the metering pintle is withdrawn from the valve seat the areas upstream and downstream of the metering area change and the static balance no longer holds. In addition to statically balanced valves, metering flow control valves have also been balanced at some intermediate point in the valve stroke by careful selection of the metering area. These valves, however, are not balance pintle valves (sometimes called globe valves) under both static and varying dynamic flow conditions.

The techniques most often used to generate balancing forces are springs, Bernoulli pressures and flow momentum.

With the spring force balancing technique, the spring is used for balancing forces over the total stroke if the force versus stroke of the pintle valve is linear under expected conditions of pressure and flow. Some attempts have also been made to balance non-linear forces with non-linear springs. The spring force balancing method achieves a degree of balancing for only fairly constant operating conditions of upstream and downstream pressures.

Under some very selected conditions, it is possible to balance a valve with Bernoulli pressure forces generated against the side of the metering pintle. The limitation of this technique is the difficulty of configuring the three dimensional geometry of the pintle such that a balance is achieved for all flow conditions. Many times the pressure-flow-stroke requirements (such as flow-stroke requirements that require stepped pintles) are such that only a small reduction in forces can be achieved with realizable geometries. The Bernoulli technique has been found to be useful only when the back pressure operating conditions are well defined.

In the flow momentum technique, reaction forces of the high velocity metered fluid are used to counter the overbalance in the closing direction of a flow-to-open valve. This technique is difficult to analyze because of the three. dimensional geometry that must be matched to some particular flow-pressure-stroke relation. Like the Bernoulliforce balancing technique, this method is limited to valves with favorable force parameters that can be counteracted with realizable geometry.

An object of the present invention is to provide a balanced metering pintle valve under both static and dynamic conditions. Another object of this invention is to provide static and dynamic balancing of a metering valve for varying operating conditions of upstream and downstream pressures. A further object of this invention is to provide for static and dynamic balancing of a metering valve with realizable geometry under varying pressure-flow-stroke requirements. Still another object of this invention is to provide static and dynamic balancing of a metering pintle valve under varying back pressure operating conditions. A still further object of this invention is to provide static and dynamic balancing of a metering pintle valve by varying generated forces as the pintle is withdrawn from the valve seat.

In accordance with the present invention, a pintle valve is dynamically balanced by generating a prescribed pressure-ratio variation with stroke. The valve mechanism includes a valve body having an interior surface defining a chamber therein. The valve body includes means for defining an inlet and an outlet communicating with the chamber. Avalve member movable within the defined chamber between a first position for closing off a flow of fluid through the chamber to intermediate positions for regulating the flow of fluid includes means for generating a force that increases with the flow of fluid through the defined chamber to balance the forces produced on the valve member. In one embodiment of the invention, the latter means includes a plurality of passages formed in the valve member.

A more complete understanding of the invention and its advantages will be apparent from the specifications and claims and from the accompanying drawings illus- FIG. 2 is a plot of an uncompensated force curve for the pintle valve of FIG. 1 with pintle forces in pounds given as a function of pintle stroke in inches;

FIG. 3 is a balanced force curve with pintle forces in pounds again plotted as a function of pintle stroke in inches;

FIG. 4 is an impedance representation of a plurality of passages formed in the pintle as they are withdrawn into the upstream pressure and vented to the downstream pressure;

FIG. 5 is a schematic technique of a throttling valve using the force balancing technique of the present invention;

FIG. 6 is a sectional schematic of an injector valve employing the force balancing technique of the present invention;

FIG. 7 is a sectional view of a three pintle injector valve wherein the dynamic forces are balanced by a plurality of passages in the center pintle;

FIG. 8 is an elevational view partially in section of the center pintle of the valve of FIG. 7; and

FIG. 9 is an end view of the center pintle of the valve of FIG. 7 showing the radial distribution of the plurality of compensating passages.

Referring to FIG. 1, the schematic illustrates a pintle valve wherein the inlet and outlet flow directions are at right angles to each other. In the valve shown, a housing 10 includes a plenum chamber 12 having an inlet passage (not shown) communicating therewith and an outlet passage 14 also in communication therewith. A metering pintle 16 moves axially within the housing 10 and forms a compensating chamber 18 opposite the outlet passage 14. A seal 20, located within an annular groove in the housing 10, engages the pintle 16 to form a fluid seal between the compensating chamber 18 and the plenum chamber 12.

Within the metering pintle 16 there is a longitudinal passage 22 communicating with the compensating chamber 18 and terminating in a restricted-flow passage 24 opening into the. outlet passage 14. Opening into the passage 22 is a plurality of longitudinally spaced compensating passages 26 through 30.

In the illustration of FIG. 1, the pintle has a cylindrical body section 32 terminating at a dual conical shaped metering area 34 terminating in a shaped surface for collimating aflow of fluid through the passage 14. The configuration of the metering area 34 in FIG. 1 provides a desired flow pattern for an injector valve.

In the operation of the valve of FIG. 1, the area of the section 32 and the metering area 34 are designed such that with the pintle in the closed position (as shown) the valve is statically balanced. That is, the forces tending to force the metering plug into a closed position substantiallyoffset forces that tend to open or move the plug away from the closed position. As the pintle 16 moves to an intermediate position from the closed off position to establish a flow of fluid from the plenum chamber 12 through the outlet 14, the plurality of compensating passages 26 through 30 are sequentially withdrawn into the high pressure upstream of the valve seat to generate aratio of upstream to downstream pressure that varies with pintle position. This pressure is conducted to the compensating chamber ,18 to generate a force on a piston 36 to counteract flow forces on the metering area 34. Since the forces of the metering area are a function of the pressure drop across the valve, a reasonably good balance between the force on the piston 36 and the metering area 34 can be achieved for a wide variation of operating conditions. Further, the plurality of compensating passages for balancing dynamic forces is workable with a wide variation of total pintle geometry. A calculation of the is made from the known uncompensated force curve.

As shown in FIG. 2, the uncompensated force curve is given by the

solid lines

38 and,40. The section of this curve given by the line 40 can be compensatedby a series of pressure steps introduced into the compensating chamber 18. As the pintle 16 is stroked, a varying combination of orifice areas, as defined by the passages 26 through 30, are presented to the upstream pressure (P,) and the downstream pressure (P,,) to generate an intermediate control pressure (P The generated control pressure P in the compensating chamber 18 is thus a function of the pintle position for a given relationship of upstream pressure P, versus downstream pressure P,,. The control pressure P, produces a force on the piston 36 to generate a force that is a function of stroke. For a balanced valve, the generated force on the piston 36 must be substantially equal and opposite to the force variation on the metering area 34. 1

As an example of dynamic balancing, consider FIG. 1 to show a step injector pintle valve that has an uncompensated force curve versus pintle stroke as shown in FIG. 2. To simplify this example, the area of piston 36 is 1 sq. in. and the upstream pressure P, is 1,000 PSI. Using the passages 26 through 30, five pressure steps are used to counteract the force curve given by line 40 of FIG. 2 to an acceptable limit, for example, below 200 lbs. as shown by curve 42 of FIG. 3. As each of the passages 26 through 30 is opened to the upstream pressure P,, with venting through the restricted flow passage 24, an analog representation of the action of thebalancing forces may be represented by the impedance diagram of FIG. 4. If P pintle force/1 sq. in., that is, the compensating pressure in the chamber 18 the following set of flow continuity equations can be written:

2 Qam Qdoum (l) where Q the flow on the upstream side of the pintle, and O the flow on the downstream side of the pintle. a This summation of flow continuity may also be written:

When P 0, that is when the valve is used in the injector flow mode, and using equation (3), the following equations for each of the steps given in FIG. 2 may b written: v

where A the area of the restricted flow passage 24,

A, the area of the passage 26,

A the area of the passage 27,

A the area of the passage 28,

A the area of the passage 29, and

4.63 1 tee tb P ses? .,.East,srithssh yssqvstismst lsa M 499 t9;

2.65141 A2A3 A4 0 A' =0.227 A 15) A =0.19l A (16) A =0.l67 A '17 A5=0.193 A0 This then yields the diameters for each of the passages 6 h q sh :0 tan stivs y intern 9f 2 D D0 D2 Do D3=0.99 D (21) D 0.46 D 22 D 0.49 D where D the diameter of the restricted flow passage 24,

D the diameter of the passage 26,

D the diameter of the passage 27,

D the diameter of the passage 28,

D, the diameter of the passage 29, and

D the diameter of the passage 30.

The diameters are based on D, which can be chosen based on contamination, allowable balancing flow and minimum drill sizes. The diameters can usually be large and still have insignificant flow compared to the valve flow rate.

As explained, the dynamic force balancing of the present invention may be used either in a throttle .valve configuration or an injector valve configuration. Referring to FIG. 5, there is shown a sectional schematic of a throttle valve including a valve housing 44 containing a first chamber 46, a second chamber 48 and a third chamber 50. Chambers 46 and 48 are separated by a valve seat 52 that engages a metering pintle 54 for controlling the flow of fluid between the first and second chambers. A passage 56 communicates with the first chamber 46 and a passage 58 communicates with the second chamber 48.

A shaft 60 of the pintle 54 is slidably mounted by a bearing and seal assembly (not shown) that is disposed in a wall of the housing 44 so that the pintle moves coaxially relative to the seat 52. The pintle has a solid cylindrical portion 62 with a diameter substantially equal to the diameter of the third chamber 50. With the pintle 54 mounted as illustrated, the section 62 separates the first chamber 46 from the third chamber 50. A seal 64, mounted in an annular groove of the housing 44 and engaging the section 62, forms a fluidtight arrangement between the chambers 46 and 50.

In the embodiment ofFlG. 5, a dynamic balancing of the pintle 54 is achieved by a plurality of compensating passages 66. through 69 formed within the generally cone-shaped section 70. Passages 66 through 69 terminate at a longitudinal passage 72 that communicate with the third chamber 50. The passage 72 terminates in a restricted flow passage 74. For any given configuration and operating condition, equations (l) through (3) of the preceding example may be used to calculate the diameter of the passages 66 through 69 and passage 74. For a throttle valve, the downstream pressure P, is not zero but will be at some finite level, depending on the load into which the valve works. It will be noted, that with a throttle valve the upstream pressure P, and the downstream pressure P, can be generated in either the chambers 46 or 48, depending on the flow through the valve.

Referring to FIG. 6, there is shown a sectional schematic of an injector valve employing the principles of the present invention. A valve housing 76 has on one of its sides an inlet- 78 for receiving liquid under high pressure from a supply line. The valve housing has a discharge orifice 80 located on an adjoining side to discharge a jet stream 82 in a direction perpendicular to the flow into the inlet 78. An actuator (not shown) mounted to the housing 76 moves a'metering pintle 84 within the housing. A shaft 86 couples the actuator motion to the pintle 84. This shaft is slidably mounted by a bearing and seal assembly 88 that is disposed in the wall of the housing 76 so that the pintle is mounted coaxially relative to the valve seat at the discharge orifice 80. The pintle 84 has a solid cylindrical portion 90 that engages a seal 92 to separate the housing chamber into first and second sections. The metering portion of the pintle 84 has a substantially conical shape.

To balance the dynamic forces on the pintle 84 for varying flow rates from the inlet 78 through the discharge orifice 80, a plurality of compensating passages 94 through 97 are formed to the conical section of the pintle and communicate with a longitudinal passage 98. The passage 98 also communicates with a discharge passage 100 to form an outlet from the section 101 of the housing chamber. Again, calculation of the diameter for each of the passages 94 through 97 and the passage 100 may be made by equations (1) through (3).

In a reduction to practice of the present invention, an injector valve having three metering pintles was provided for controlling fuel injection into a rocket engine. Referring to FIGS. 7 through 9, there is shown a three metering-pintle injection valve. Each of the

metering pintles

102, 104 and 106 controls fluid flow by displacement from a

valve seat

108, 110 and 112, respectively. Each of the valve seats is mounted in a manifold plate 114 and held in place between an orifice 116 and a holding plate 118. The valve housing 120 is mounted to the manifold plate 114 and forms a plenum chamber 122 therewith; Fluid enters the chamber 122 through

passages

124 and 126.

The metering pintles 102, 104 and 106 are supported on a yoke-128 that includes a cylindrical section 130 extending into the housing 120 to form a compensating chamber 132. Guide pins 134 and 136, mounted into the housing 120,serve to orient each of the metering pintles with the respective valve seat. Linear motion is imparted to the yoke 128 through a ball-screw (not shown) coupled to a drive shaft 138. The drive shaft 138 threadedly connects to the yoke 128. The shaft 138 passes through the housing 120 and engages a seal 140 to form a fluid-tight seal between the compensating chamber 132 and the passage 142. A seal 144, engaging the cylindrical section 130 of the yoke 128, forms a fluid-tight seal between the compensating chamber 132 and the plenum chamber 122. A spring 146 biases the yoke 128 into a closed position. This spring'may also serve to partially balance the forces on the

metering pintles

102, 104 and 106.

The primary compensation force for the

pintles

102, 104 and 106 is accomplished by compensating passages in the metering pintle 104. As shown in FIGS. 8 and 9, the metering pintle 104 includes a generally conical section 148 and a cylindrical section 150. The cylindrical section 150 terminates at a threaded section 152. When assembled with the yoke 128, a nut 154 engages the threaded section 152 to hold the metering pintle 104 in position. When in place, the section 150 engages an O-ring seal 156. Section 150 terminates in a chamber 158 connected to the compensating chamber 132 by means of a passage 160.

As illustrated in FIGS. 8 and 9, a plurality of compensating passages 162 through 166 are formed in the conical section 148. Each of these passages terminates in a longitudinal passage 168 that opens into the chamber 158. The downstream portion of the passage 168 terminates in a restricted flow passage 170. The passages 162 through 166 are both radially displaced about the conical section 148 and longitudinally displaced such that they will be subsequently withdrawn into the upstream pressure in the plenum chamber 122.

The general conical shape of the metering portion of the pintle can be modified according to control characteristics desired. A preferred shape provides linear control; that is, the quantity of flow of liquid through each of the valve seats 108, 110 and 112 varies in equal increments for equal changes in distance of travel of the metering pintles in the axial direction. When a collimated stream in an axial direction is not required for a low rate of fluid flow, the apex of the pintle need not be elongated to provide a pointed guide. Thus, the conical shape of the metering pintles described is not intended to limit the invention to such a configuration.

To calculate the diameters of each of the compensating passages 162 through 166 and passage 170, the equations (1) through (3) of the example are employed. The calculations are independent of the use of three metering pintles instead of the one illustrated in FIG. 1.

While several embodiments of the invention, together with modifications thereof, have been described in detail herein and shown in the accompanying drawings, it will be evident that various further modifications are possible without departing from the scope of the invention.

What is claimed is:

1. A valve mechanism for regulating the flow of fluid comprising:

a valve body having an interior surface defining a chamber therein, said valve body having means for defining an inlet and an outlet communicating with said chamber,

a valve member movable within the defined chamber between a first portion for closing off a flow of fluid through said chamber to intermediate positions for regulating the fluid flow, and

means within said valve member cooperating with the valve body for generating a force on the valve member that varies with the pressure differential across the inlet and outlet of the defined chamber to balance the forces produced on said member.

2. A valve mechanism for regulating the flow of fluid as set forth in claim 1 wherein said means includes a plurality of compensating passages formed within said valve member to be successively withdrawn into the fluid flow through the inlet into the defined chamber.

3. A valve mechanism for regulating the flow of fluid as set forth in Claim 2 wherein said compensating passages are displaced longitudinally in said valve member.

4. A valve mechanism for regulating the flow of fluid as set forth in Claim 3 wherein said passages are radially distributed around said valve member.

5. A valve mechanism for regulating the flow of fluid comprising:

a valve body having an interior surface defining a first and second chamber, said valve body having means for defining an inlet and an outlet communicatin w'th said first ch mber a valve m%mber movable within said first and second chambers between a first position for closing off a flow of. fluid through said first chamber to intermediate positions for regulating the fluid flow, and means within said valve member for producing a pressure in said second chamber to produce a compensating force on the valve member that varies with the pressure differential across the inlet and outlet ofuthe first chamber to balance the forces produced on said valve member.

6. A valve mechanism for regulating the flow of fluid as set forth in claim 5 wherein said means includes a plurality of compensating passages formed within said valve member to be successively withdrawn into the fluid flow through said first chamber.

7. A valve mechanism for regulating the flow of fluid as set forth in claim 6 including a passage communicating with said plurality of passages, to said second chamber and the outlet of said valve body, and

restriction means in said passage to produce a controlled flow of fluid from said second chamber.

8. A valve mechanism for regulating the flow of fluid as set forth in claim 7 wherein said valve member has a generally conical configuration and said plurality of passages are displaced longitudinally through said conical section.

9. A valve mechanism for regulating the flow of fluid comprising:

a valve body having an interior surface defining a first chamber, a second chamber and a third chamber, said valve body having means for defining an inlet communicating with said first chamber and an outlet communicating with said second chamber,

-a conically shaped valve member movable within said first and third chambers between a first position for closing off a flow of fluid through said first chamber to said second chamber to intermediate positions for regulating the flow of fluid between the inlet and outlet,

a longitudinal passage through said conically shaped valve member for forming a communicating path between said second chamber and said third chamber,

restriction means in said passage at the end toward said second chamber for controlling the flow of fluid through said longitudinal passage, and

a plurality of compensating passages formed within said valve member communicating with said first passage to be successively withdrawn into the flow of fluid through the inlet to generate a pressure in said third chamber that varies with fluid flow to balance the forces produced on said valve member.

10. A valve mechanism for regulating the flow of fluid as set forth in claim 9 wherein said plurality of compensating passages are displaced longitudinally in said conically shaped valve member.

1 1. A valve member for regulating the flow of fluid as set forth in claim 10 wherein said plurality of compensating passages are radially displaced around said conical shaped valve member.

CERTIFICATE OF v( J()RRE( ITION Patent No. 3, 209 Dated Cctober 24, 1972 Inventor-(s) Joe D. Usry It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

F I q Col 2, line 41, after "schematic" cancel ."technique" and insert "sectional view..

Col. 4, line 23, "Transporting" should be --Transposi ng-.

line .48, "2.65A A A +'A -A AO= 0" should be line 49, "1 73A a3.l 73A -A -A --A A 0-" should be line 50, "1 25A a3.1 2SA '+l 25A -A -A -A 0'! should be --1.25A +1.25A' +1.25A -A -A -A 0--;

line 51 "0.95A a3 .0.95A +0 .95 A +95A -A -A 0" should be (SEAL) Attest:

EDWARD M.FLETCHER ,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents

Claims

1. A valve mechanism for regulating the flow of fluid comprising: a valve body having an interior surface defining a chamber therein, said valve body having means for defining an inlet and an outlet communicating with said chamber, a valve member movable within the defined chamber between a first portion for closing off a flow of fluid through said chamber to intermediate positions for regulating the fluid flow, and means within said valve member cooperating with the valve body for generating a force on the valve member that varies with the pressure differential across the inlet and outlet of the defined chamber to balance the forces produced on said member.

5. A valve mechanism for regulating the flow of fluid comprising: a valve body having an interior surface defining a first and second chamber, said valve body having means for defining an inlet and an outlet communicating with said first chamber, a valve member movable within said first and second chambers between a first position for closing off a flow of fluid through said first chamber to intermediate positions for regulating the fluid flow, and means within said valve member for producing a pressure in said second chamber to produce a compensating force on the valve member that varies with the pressure differential across the inlet and outlet of the first chamber to balance the forces produced on said valve member.

7. A valve mechanism for regulating the flow of fluid as set forth in claim 6 including a passage communicating with said plurality of passages, to said second chamber and the outlet of said valve body, and restriction means in said passage to produce a controlled flow of fluid from said second chamber.

9. A valve mechanism for regulating the flow of fluid comprising: a valve body having an interior surface defining a first chamber, a second chamber and a third chamber, said valve body having means for defining an inlet communicating with said first chamber and an outlet communicating with said second chamber, a conically shaped valve member movable within said first and third chambers between a first position for closing off a flow of fluid through said first chamber to said second chamber to intermediate positions for regulating the flow of fluid between the inlet and outlet, a longitudinal passage through said conically shaped valve member for forming a communicating path between said second chamber and said third chamber, restriction means in said passage at the end toward said second chamber for controlling the flow of fluid through said longitudinal passage, and a plurality of compensating passages formed within said valve member communicating with said first passage to be successively withdrawn intO the flow of fluid through the inlet to generate a pressure in said third chamber that varies with fluid flow to balance the forces produced on said valve member.

11. A valve member for regulating the flow of fluid as set forth in claim 10 wherein said plurality of compensating passages are radially displaced around said conical shaped valve member.