DE2500723A1 - FLUID THROTTLE DEVICE - Google Patents

Description

PATENT ADVOCATES A. GRÜNECKER

H. [CNKELDEY

DR.-ΙΝβ.

W. STOCKMAlR

DR.-INS. AeECCAUTECH)

ο ε: η rt »7 o -a ^κ · ^SCHUMANN

L 0 UU IL, si ^DR - ^RER NAT. - DIPL.-PHYS.

P. H. JAKOB

G. BEZOLD

OR. RER. MAT. · D1PU.-CHEM.

MUNICH

E. K. WEtL

DR. RSR. OEC INS.

LINDAU

8 MUNICH 22

MAXIMILIANSTRASSE 43

January 10 Λ373 P 8902

iDour Agency Aktiebolag

Svärdlangsvägen 46 _y 121 72 Johannesnpv, Sweden

Fluid valve selector

The invention relates to a throttle device for liquids or gases that flow in lines, valves or the like.

When fluids are throttled, they occur frequently disturbing tones or noises and are on the line or the valve on or close to the throttle often Damage from erosion observed. This depends on the

509829/0675

TELEPHONE (OBS) 22 28 62 TELEX Ο5-2938Ο TELEGRAMS MONAP

ho lien. Flow velocity and the simultaneous reduction of the static. Pressure from the throttle point, i.e. the constriction (vena contracta) occur. According to well-known, physical laws is the sum the pressure energy and the kinetic energy at each tunnel of a medium flowing without energy loss constant. If the flow medium flows through a throttle point, the speed of the flow medium increases and thus the dynamic pressure. This has the consequence that the static pressure at the throttle point drops. For example, the throttle point or constriction is located in a valve at the opening between the valve seat and the valve element. "If that, flow medium is a liquid is, the pressure at the constriction to a value below the vapor pressure drop so that vapor bubbles occur in the fluid. This is where the well-known occurs Phenomenon called cavitation. If the Cavities formed in this way implode, vibrations and annoying noises occur in the valves or the Pipe system on. Heavy wear is caused and the service life of the throttle device or the valve is increased considerably reduced.

In Fig. 1, a single-stage throttling is shown schematically in a line through which a liquid flows. The liquid flows through the area A ₁ with a pressure P, goes through the constriction A at pressure P and sets the

. ve ve

Flow through area A continues at pressure P. In the lower part of FIG. T, the change in the static pressure in the liquid during the flow through the throttle point is shown. In Fig. 1, the vertical axis shows the static pressure and the horizontal axis the pipe length. This figure shows that the pressure P _T up to immediately

509823/0675

the throttle point is relatively constant that there the pressure drops sharply to a value P, which in the

vc

posed case is below the vapor pressure P, that afterwards the pressure rises to a reaction pressure with the value P ", after the liquid has flowed through the constriction, and that the pressure, after being on a has stabilized lower value, is held constant at the value P substantially.

There is one for every throttle point or valve Variable t>, which are used for different types of throttling devices, for example Ve ± ile, and for different dimensions of the opening of the valve is different. Of the fc value can be defined in the following way:

P ₁ -P

PP
* 1 2

The t? Value is a measure of the sensitivity for resp. Probability of cavitation at the throttle point. Around the throttle points, for example the valve, against damage To protect surfaces from erosion and damage from cavitation, it has been suggested that the are exposed to such attacks to coat with hard surface materials, for example with the hard metal alloy Stellite. However, the coating with hard metal is expensive and complicated, and the hard metal coating cannot, of course, prevent the generation of noise and vibration. It is also suggested been a gradual change in the speed of the Flow mediuras along a longer part of the throttle device to make it possible by providing this with a number of relatively long parallel holes, through which the liquid or gas can flow. the

B09829 / 0675

Holes can be provided with a conical or rounded leading edge, and in order to further improve the properties it has been proposed that the holes be provided with a friction-increasing surface, for example by providing the holes with threads. This is not a completely satisfactory solution to any of the problems of eliminating cavitation, noise, vibration, and damage from erosion. Despite this design of the throttle point, there is often a relatively high h value, which means that the throttle point produces a relatively low throttling effect, as has already been mentioned.

It has also been proposed to pass the throttle to form two successive throttle devices of the same design. This makes it possible to b- ¥ ¥ erte to reduce somewhat, whereby a somewhat increased throttling effect can be achieved. But also with one of these Construction of the throttle point, it is not possible to the desired extent to avoid cavitation and noise, To reduce vibrations and erosion.

The invention is based on the object of creating a throttle device for flow media, by means of which one strong throttling effect can be achieved without disturbing Noises and vibrations are generated and without the risk of such severe erosion and cavitation, as it occurs in well-known Dr'ös se! institutions.

The basis of the invention is the knowledge that it is possible to reduce strong pressures at throttle points for continuous or variable flows, for example on pressure reducing devices, printer

509829/0675

elevation devices, valves, etc., without cavitation, disturbing noises, vibrations, speed erosons etc. to achieve that the fluid flow in two or more successive steps is throttled, so that the static pressure at each constriction to one ¥ ert is reduced, which is not lower than the pressure value, for example the vapor pressure of the fluid, at which disturbing noises, cavitation and speed eroson occur. According to a particularly preferred embodiment of the invention are the different throttle levels of the combined Throttle device designed so that the static pressure at the constriction of each throttle point is essentially has the same value, whereby an optimal throttling is achieved. In valves with the inventive Throttle device are provided, the opening areas for each throttle point are preferably designed so that one there is a certain relationship between the various opening areas regardless of the extent to which the valve is open, so that the static pressure at the constriction of each throttle point is independent of the extent to which the valve is opened assumes the same value. For the invention it is essential that the opening areas in such a valve under Consideration of the total Ό-value of the valve designed in this way are that the static pressure at the constriction of all throttle stages is essentially one and the same Assumes the value that, when the valve is loaded to the limit of cavitation, is the critical pressure for the flowing Fluid corresponds, i.e. the vapor pressure if the flow medium is a liquid.

The fluid throttle device according to the invention is defined in the claims marked.

50982 97 0675

By means of the fluid throttle device according to the invention is the static pressure in a liquid or a gas in two or more successive stages or Steps diminished so that tones, noise and damage from erosion in a vain pipe or valve be avoided as much as possible.

Further features and advantages of the invention emerge from the following description of embodiments with reference on the drawings. It should be understood, however, that the invention is not limited to those described and illustrated Embodiments is limited and that numerous different embodiments are possible within the scope of the invention are. Show it:

1 schematically shows a throttle point in a pipe or a line and an associated pressure diagram for part of the line in the vicinity of the throttle point;

FIG. 2 in a manner corresponding to FIG. 1 with a line two successive throttling points;

3 schematically shows a valve with two successive ones Throttle stages or throttle steps;

Fig. 4 in Fig. 3 in a corresponding manner schematically

Valve with three successive throttle stages;

5 shows a cross section through an inventive Control valve with two successive throttle stages;

509829/0675

Fig. 6

a modified embodiment of the invention; and

7 shows a flat development of certain flow openings of the valve according to Pig. 6th

509829 / OG7R

As already mentioned, Fig. 1 shows how the static pressure in the constriction (vena contracta) of a throttle point drops below an ¥ ert P, at which steam is generated

can, so that cavitation, annoying noises and damage from erosion can occur. The invention is explained in the same schematic manner in FIG. Two throttle points 1 and 2 are provided, which follow one another. According to FIG. 2, the throttling takes place in two successive steps from an inlet pressure P ₁ , which has the same value as the inlet pressure P in FIG. 1, to an outlet pressure P ₉ , which is equal to the outlet pressure P "in FIG. In the constriction A _{1 of} the first throttle point 1 according to FIG. 2, the pressure is _{lowered to a value P 1} which is higher than the critical pressure P. Subsequent to

Constriction of the throttle point 1, the pressure rises to a constant pressure P ″ after it has risen to a reaction pressure P. Thereafter, the pressure P in the constriction A _{2 of} the second throttle point _{2 is} lowered to a value P 2, which is also higher than the critical pressure P, after which

ν '

the pressure assumes the value of the outlet pressure P_ following a reaction pressure P ". Fig. 2 shows that it is possible by reducing the pressure in two successive throttling steps to achieve the same throttling as is achieved according to FIG. 1 in a single step, without the pressure in one of the two throttling steps below the critical pressure P drops, so that it is consequently possible to reduce or eliminate cavitation, noise, erosion, damage and vibrations. So that this result is achieved and so that it is possible to achieve the greatest possible throttling, it is essential according to the invention that the throttling takes place in the two steps in such a way that the pressure P "... in ^{d <} 3 ^r constriction for the throttle point 1 equal to the pressure P _q2 in the

509829/0675

lacing for the throttle point 2 is »

In the case of valves, the pressures P ₁ and P "should be the same regardless of the extent to which the valve is opened. Furthermore, the pressure in the constriction should not fall below the critical pressure P at an optimal to value. The ^ J- ¥ ert φ ₁ for the throttle point or throttle stage 1 and the i? - ¥ ert Ö _p for the throttle point or throttle stage 2 can be different, and the total £? Value for a two-stage throttle should be fulfill the following relationship:

^ total

When the pressure in two or more successive steps to a substantially equal pressure value in the constriction of the various throttle stages is reduced, the pressure reduction must necessarily be carried out for each successive one Throttle level become lower. Among other things, this has the consequence that the cross-sectional or Opening area for each successive throttle stage must increase. The amount of increase in the opening area for each successive throttle stage depends on several different circumstances and must usually be determined by experiment or experience.

In FIG. 3, a valve is shown schematically which has two successive throttle points 1 and 2 and which represents a practical embodiment of the system shown in FIG. In this embodiment, the throttle stage has three passages or channels 3 and the throttle stage 2 has six passages or channels k. The channels 3 and h are relatively long and can be with a rough surface or with

509829/0675

Flow resistances, for example threads or the like, be provided so that a further increase in the stream resistance in the channels is provided. A valve piston can be moved up and down in front of the inlet of the channels 3 and h . In Fig. 3, the valve piston 5 is shown in. Such a position that fluid can flow through two channels of the first throttle stage and four channels 4 of the second throttle stage. Thus a substantially constant area relationship between the channels 3 and exist h remains, the valve piston 5 two orifice plates ^5a and 5b, with an orifice plate '5 ^a, the inlets of the channels 3 and the other orifice plate 5b, the inlets of the channels can lock h . Regardless of the extent to which the valve is opened, the pressure in the constriction of the respective throttle point 1 or 2 is essentially the same, and the channels 3 and K should be dimensioned so that when the valve is maximally loaded or at the limit of Cavitation works, the pressure in the constriction assumes a value at or slightly above the critical pressure P, which corresponds to the vapor pressure if the flowing medium is a liquid.

In Fig. H , another valve according to the invention is shown, which is provided with three throttle stages 6, 7 and 8 and in which the first throttle stage has three passages or channels, the second throttle stage five passages or channels and the third throttle stage nine passages or channels. Has channels. The total flow area of the second throttle stage 7 is larger than that of the first throttle stage 6 ″, and the total flow area of the third throttle stage 8 is in turn larger than that of the second throttle stage 7. The valve piston has three throttle discs 5 ^a > 5 b and 5 c, each of which a throttle stage 6 or * 7 or 8 can close.

509829/0675

FIGS. 3 and U show how the flow areas of the various throttle stages can be enlarged by increasing the number of flow channels; however, it is obvious that the invention in its simplest embodiment can have only one flow opening for each throttle stage and that the relationship between the areas of the flow openings of the various throttle stages can be changed by changing the width of the flow opening. However, this can also be done in any other suitable manner.

Fig. 5 shows a cross section through a two-stage valve with a valve housing 9 'which has an inlet chamber 10 and an outlet chamber 11. The valve housing 9 is with an inner, cylindrical valve piston chamber 12, in which a valve piston 13 is provided by means of a valve stem 14 can be moved up and down. The valve piston chamber 12 is closed at the bottom of the valve by a base plate 15 and at the top by a head plate 16 which the valve stem 14 passes through. For setting the valve piston an external adjustment device, which is not shown in the drawing, is generally used. The inlet chamber 10 and the outlet chamber 11 are conventional Way arranged in S-configuration, and in the outlet chamber 11 a sleeve 17 is mounted so that they on the one hand on a wall 18 between the inlet chamber 10 and the outlet chamber 11 and on the other hand at the bottom of the valve and the bottom plate 15 seals. The outlet chamber 11 comprises an annular chamber 19 around the sleeve 17 »and, in a similar manner, an annular chamber 20 around the valve piston 13 · The Valve piston 13 is movable in the sleeve 17, and between a sealing ring 21 seals both.

509829/0675

The valve piston 13 is designed as a socket which both is open at the top as well as at the bottom, so that pressure within the valve piston is in the same way both in the chamber above of the valve piston as well as in the chamber below the valve piston. This will cause axial forces on the Pistons lifted, which would otherwise make adjustment of the valve piston difficult or even unintentional Would cause self-adjustment of the valve piston. In an axial section that is essentially the The height of the annular chamber 20 corresponds to the inlet end Valve piston has a plurality of inlet channels 22 through which the inflowing fluid into the interior of the valve piston forming Socket enters. This is passed through the sleeve 17 downwards. In an axial section of the sleeve, which corresponds essentially to the height of the outlet-side annular chamber 19, has the sleeve in a corresponding manner a plurality of outlet channels 23 through which the fluid exits to the outlet chamber 11.

As previously explained in connection with FIGS. 2 and 3 becomes, the total flow area of the outlet channels 23 exceeds the total area of the inlet channels 22. The relationship between these areas is essentially constant, regardless of the extent to which the valve is opened. In Fig. the valve is shown in its fully open position with the valve piston in its upper position Location near the top plate 16 is located. When the valve piston is moved downwards, the sleeve 17 closes the inlet channels 22 of the valve piston 13 'one after the other and in a corresponding manner Thus, a lower portion 24 of the valve piston sequentially closes the outlet channels 23 · The relationship between the Areas of the outlet channels 23 and the inlet channels 22 is like this chosen that the static pressure of the flowing medium in

509829/0675

the constriction of the inlet channels 22 and in the constriction of the outlet channels 23 essentially assume the same ¥ ert. Furthermore, these areas are chosen so that, • when the valve is loaded to the limit of cavitation and the flow medium is a liquid, the static pressure of the two channel systems 22 and 23 has a value that is at or slightly above the critical pressure. In the embodiment described, the inlet channels 22 are formed in the valve piston 13 and the outlet channels 23 are formed in a part of the valve housing; However, it is obvious to those skilled in the art that the inlet channels and the outlet channels can be formed in any other suitable manner in the valve piston or the valve housing, provided that the inlet channels 22 and the outlet channels 23 are throttled parallel to one another, so that the desired relationship between the areas of the channels is maintained regardless of the degree of opening of the valve. It is also obvious to a person skilled in the art that the valve can be provided with three or more throttling points, the total flow area for each subsequent throttling point through which the fluid flows being greater than that of the preceding throttling point.

In FIGS. 6 and 7, an embodiment of the invention is shown which is somewhat modified in comparison with the embodiment described in connection with FIG. In the following description, the same reference numerals are used for the same parts.

The valve housing 9 has an inlet or an inlet chamber 10 and an outlet or an outlet chamber 11. An inclined wall 18 extends in a conventional manner through the valve, and A hole 18a, which has a valve piston, goes through this wall

509829/0675

can accommodate. The valve piston 13, however, is not arranged directly in this hole, but the hole 18a has a bush 17 which will be described further below and into which the valve piston 13 is slidably inserted. The sleeve 17 is permanently installed in the valve and is sealed off from the various parts of the valve housing 9 ^{by means of seals 17 a.}

A head plate 16 secured by means of screws closes from the space into which the sleeve 17 is inserted. The top plate 16 is in contact with via a seal i6a the valve housing e and includes a bearing support i6b for the valve stem i4.

For the function of the valve, it is of no importance how the force is transmitted from the valve stem 14 to the valve piston 13. The valve piston can be designed so that only the valve piston is moved by means of the valve stem; however, the valve can also be designed as a valve with an extending valve stem or as a valve with a non-extending valve stem. It is only important that the valve piston is moved in the axial direction, it being irrelevant whether this movement is combined with a simultaneous rotary movement. For the sake of simplicity, the power transmission between the valve stem 14 and the valve piston 13 in the embodiment is shown in FIG. Of a pin 13 ^a "which passes through the valve piston 13, and a bearing bush 13h" in which the valve stem is mounted i4.

There are two sets of holes in the sleeve 17, one set of holes 22 that communicate with the inlet chamber 10 communicating, and another set of holes 23,

50 9829/0675

which are in communication with the outlet chamber 11. These Holes can be of any particular shape to give the valve any particular characteristic. So are the inlet holes 22 in the sleeve 17 of the valve are shown as being substantially Y-shaped, with the major axis runs parallel to the valve stem. If necessary, can also the outlet openings 23 have any particular shape; however, it is usually sufficient to achieve the desired results Fluid characteristic that a set of holes, i.e. the holes 22 or the holes 23> have the aforementioned special shape.

As with the previously described embodiment of the invention, the total area of the inlet holes 22 is smaller than the total area of the outlet holes 23, and the relationship between these areas is chosen so that for both the Inlet holes 22 and outlet holes 23 in the constriction the same pressure value is achieved. Furthermore are the area and the shape of the holes chosen so that the lowest pressure in the constriction both at the inlet holes and at the outlet holes equal to or is slightly higher than the critical pressure of the valve, if this is in the case of a liquid up to the limit of cavitation is burdened.

The valve according to FIG. 6 is shown in its closed position. The lower edge 28 of the valve piston 13 lies thereby deeper than the lowest point of any of the holes 22, and the valve piston includes a seal 21 therewith no fluid leakage occurs. The valve piston 12 comprises several such seals. Before the bridge of the sleeve 17, which exists between its sets of holes 22 and 23, if the valve piston 13 has a number of openings 26., between which there are webs 27, which the lower part

509829/0675

13 'and the upper part 13 "of the valve piston together. As already mentioned, the valve piston 13 is tubular, so that there is a free connection between the upper valve chamber 12a and the lower valve chamber 12b.

The valve according to the invention described works in the following way: The valve is opened by pulling up des.Ventilschaftes 14, whereby the valve stem moves the valve piston upwards ^{due to the connection to the holder and the pin 13 a.} As soon as the lower edge 28 of the valve piston comes into line with the lowermost parts of the holes 22, a previously closed connection between the inlet chamber 10 and the lower valve chamber 12b is opened. It should be noted that the inlet chamber 10 is continued by an annular chamber 20 which extends completely around the sleeve 17. Therefore, there is at all inlet and Throttle channels 22 of the set of these channels have essentially the same pressure. At substantially the same time that this connection is opened, the upper edges of the openings 2.6 of the valve piston 13 are moved to a position above the lower edges of the set of holes 23 of the liner, thereby establishing a connection from the chamber inside the valve piston 13 to the annular chamber 19, which is a continuation of the outlet chamber 11. In this position there is a controlled flow of the medium controlled by the valve. It is obvious that by further pulling up the valve piston 13 by means of the valve shaft Ik, the passage channels are enlarged or increased. It should also be clear that the valve can be provided with any desired control characteristic by giving some particular shape to one or the other set of holes 22 and 23, respectively, of the sleeve 17.

509829/0675

Reference is made to FIG. 2 at the same time. It should be clear that there is a pressure in the inlet chamber 10 which _{corresponds to the pressure P 1} , that in the chamber inside the valve piston there is a pressure which corresponds to the intermediate pressure P and that in the outlet chamber 11 there is a pressure which corresponds to the outlet pressure P _p. The intermediate pressure P ″, which prevails inside the valve piston, has no axial component, since the valve piston is open both at the top and at the bottom. Therefore, on the one hand, the valve housing 9 and, on the other hand, the head plate 16 of the valve counteract this pressure, but the valve piston 13 is not acted upon in the axial direction. On the other hand, of course, a radial pressure acts on the valve body; however, since the vettile body is believed to have a circular cross-section, there is a complete balance of the various components of this radial pressure.

This is of great importance in automatic control of the valve. There are no pressure forces acting on the valve piston, which have to be overcome by a control device which acts via the valve stem 14. However frictional forces act between the valve piston and the Cans, but they are negligibly small. Therefore, it is possible for the valve stem to act even with small forces movement of the valve piston during fully balanced conditions and with a high degree of accuracy to care. By dividing the throttling into two or more consecutive ones in the manner previously described Steps or stages it is possible to achieve an optimal throttling of the flow medium without the danger cavitation, noise, vibrations or damage caused by erosion. By providing - -as this in the

509829/0675

Figures 5 to 7 - that the pressure in the upper part of the valve piston chamber 12 is essentially equal to the pressure in its lower part, the required actuating forces for the valve piston can be reduced to a minimum. Within the inlet channels 22 of the valve piston 13 and / or in front of the outlet channels 23 of the sleeve 17, a device for speed equalization, for example a device 25 ', can be attached, whereby the speed of the Ehuds is made uniform in different sections of the valve piston chamber 12, so that the fluid after flowing through the inlet channels 22, its speed cannot increase unhindered, as a result of which the X) values for the valve can be further improved. The device 25 for speed equalization also has the effect that the flow of the fluid is evenly distributed to the outlet channels 23, so that no part of the sleeve 17 is more heavily loaded than another part.

Patent claims:

503829/0675

Claims (12)

Patent claims . Fluid throttle device, characterized by two or more successive throttle stages (1, 2; 6, 7> 8) ι where the flow area for each throttle stage is greater than that Flow rate of the previous throttle stage. 2. Fluid throttle device according to claim. 1, characterized in that the total flow areas of the various throttle stages (1, 2; 6 _r 7 »8) are in such a relationship that the static pressure in the constriction (vena contracta) of each throttle stage has essentially the same value. 3 »Pluiddhrottle device according to claim 2 for a control valve, characterized in that the flow area of each throttle stage is changed when the valve position is changed, and that the different throttle stages their mutual relationship regardless of the extent of the opening of the valve. k * Fluid throttle device according to claim 3 »characterized in that the flow areas of the different throttle stages (i, 2; 6, 7» 8) are such that the static pressure in the constriction assumes a value at each throttle stage which corresponds to the critical pressure value or is slightly above this when the valve is loaded to the limit of its critical pressure drop or, in the case of a liquid, to the limit of cavitation. 5. Fluid throttle device according to claim 3 or 4, characterized 509829/0675 characterized in that the controllable throttle device the Flow openings of each throttle stage (1, 2; 6, 7 »8) throttled parallel to one another. 6. Fluid throttle device according to one of claims 1 to 5 »characterized in that each throttle stage has a plurality of parallel holes (3, k; 22, 23) which are significantly longer than their diameter. 7 «fluid throttle device according to claim 6, characterized in that that the holes (3, 4; 22, 23) are grooved or threaded or otherwise with friction-increasing Surfaces are provided. 8. Fluid throttle device according to one of claims. 3 to 7 » characterized in that the controllable throttle device (5) is designed so that it only has an axial Throttle movement can cause it to rotate Throttle movement can fill in or that it is a combined one can perform axial and rotary throttle movement. 9 · Fluid throttle device according to one of Claims 1 to 8 for a valve with a valve housing which has an axially movable valve piston, characterized in that the Throttle stages are provided in the valve piston (13). 10. Fluid throttle device according to claim 9 »characterized in that that a throttle stage in the valve piston (13) and a further throttle stage in the valve housing (9) or a any other part (I7) is provided therein is mounted. 11. Fluid throttle device according to one of claims 3 to 8, ■ characterized in that all throttle stages in one 509829/0675 permanently mounted part of the throttle device provided are. 12. Fluid throttle device according to one of claims 1 to 11, characterized in that a device (25) for Speed adjustment in the form of a close-knit Network or a throttle plate between, · in front of or behind the throttle stages. 509829/0675