Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
FLOW RESISTANCE DEVICE
Document Type and Number:
WIPO Patent Application WO/2001/031242
Kind Code:
A1
Abstract:
The flow resistance device (7) for controlling flow rate and reducing fluid pressure causes the fluid of extremely high pressure to have the flow rate and pressure reduced to a desired level. The flow resistance device (7) consists of a cylindrical disc stack constituted by a plurality of identical circular discs (15) axially stacked to control the flow of fluids between fluid inlet through holes (43) and outlet through-holes (48). The discs (15) have a plurality of T-shaped through-holes (44-46, 49-51) and rectangular through-holes (52-57) arranged at the same angle and interval. The discs (15) are stacked being individually rotated at a predetermined angle and combined together in an overlapping relationship. Thus a three-dimensional tortuous flow path structure and a plurality of vortex generating spaces (30-37) are created, which decrease the kinetic energy of the fluid passing through the flow resistance device (7), and the peak frequency for the noise is shifted to a higher frequency level, with a minimum of noise, vibration, cavitation, abrasion, corrosion and blocking with foreign materials in the flow resistance device (7) and equipment using the same.

Inventors:
KWON KAB-JU (KR)
KIM YOUNG-BUM (KR)
Application Number:
PCT/KR2000/001102
Publication Date:
May 03, 2001
Filing Date:
October 04, 2000
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
KWON KAB JU (KR)
KIM YOUNG BUM (KR)
International Classes:
F16K1/00; F16K47/08; (IPC1-7): F16K47/08; F15D1/00; F16L55/027
Foreign References:
US5819803A1998-10-13
EP0727605A11996-08-21
US3780767A1973-12-25
Attorney, Agent or Firm:
Kim, Young-ok (Yeonjae-ku Pusan 611-085, KR)
Download PDF:
Claims:
WHAT IS CLAIMED IS :
1. A resistance device for controlling flow rate and reducing fluid pressure in a disc type cylindrical flow resistance module used in the control of fluids, the resistance device comprising: A plurality of annular coupling holes being aligned along the circumferential direction of the discs ; a first through hole pattern being defined by rectangular grooves and a plurality of Tshaped through holes, wherein the Tshaped through holes being regularly aligned in the radial direction between a rectangular groove having a fluid inlet area at the inner circumference of the disc and a second rectangular groove having a fluid outlet area on the outer circumference of the disc ; a second through hole pattern forming a predetermined angle with the first through hole pattern in the circumferential direction, and defined by a plurality of Tshaped rightangle turn flow path through holes regularly aligned in the radial direction ; and third and fourth through hole patterns forming a predetermined angle with the first and second through hole patterns in both circumferential directions, and defined by a plurality of rectangular holes regularly aligned in the radial direction, wherein the four patterns each having angular symmetry are regularly arranged in the circumferential direction, wherein a plurality of the identical discs with the patterns formed therein are combined together to form a disc stack, wherein four identical discs are individually rotated at a predetermined angle and combined together in an overlapping relationship to sequentially arrange the four patterns in the axial direction of the disc stack, thereby forming the tortuous flow paths in the circumferential and radial directions, wherein the four discs are combined together in a regularly overlapping relationship to form a disc stack, thereby forming the threedimensional tortuous flow paths arranged in the axial direction of the disc stack.
2. The resistance device as claimed in claim 1, wherein the threedimensional tortuous flow paths provide a vortex generating space prior to a rightangle turn, the vortex generating space being formed by rectangular hole patterns in the axial direction of the disc stack and by Tshaped flow path through hole patterns in the radial and circumferential directions of the disc stack.
3. The resistance device as claimed in claim 1, wherein the threedimensional tortuous flow paths provide the fluid entering holes at the inlet of the individual disc and the fluid exhausting holes at the outlet of that disc.
4. The resistance device as claimed in claim 1, wherein the crosssectional area of the threedimensional tortuous flow paths crossed by the discs varies as the discs are rotated at a predetermined angle and combined together in an overlapping relationship.
5. The resistance device as claimed in claim 1, wherein the threedimensional tortuous flow paths have the crosssectional area repeatedly increased than the initial crosssectional area and reduced with the progress of the flow.
6. The resistance device as claimed in claim 1, wherein the individual through holes of the discs have a round inner edge.
7. The resistance device as claimed in claim 1, wherein the threedimensional tortuous flow paths has: the first through hole pattern defined by a plurality of Tshaped through holes being regularly aligned in the radial direction between a rectangular groove having a fluid inlet area at the inner circumference of the disc and a second rectangular groove having a fluid outlet area on the outer circumference of the disc ; and the second through hole pattern forming a predetermined angle with the first through hole pattern in the circumferential direction, and defined by a plurality of Tshaped rightangle turn flow path through holes regularly aligned in the radial direction, wherein the four patterns each having angular symmetry are regularly arranged in the circumferential direction, wherein a plurality of the identical discs with the patterns formed therein are combined together to form a disc stack, wherein two identical discs are individually rotated at a predetermined angle and combined together in an overlapping relationship to sequentially arrange the two patterns in the axial direction of the disc stack, thereby forming the tortuous flow paths in the circumferential and radial directions, wherein the two discs are combined together in a regularly overlapping relationship to form a disc stack, thereby forming the threedimensional tortuous flow paths arranged in the axial direction of the disc stack.
8. The resistance device as claimed in claim 1, wherein the threedimensional flow paths have outlet through holes 471 and 472 of the first through hole pattern paired with through holes 571 and 572 for a groove forming flow path of the fourth through hole pattern with respect to through holes 511 for the both direction turning flow paths of the second through hole pattern, so as to constitute a plurality of outlets 481 and 482. AMENDED CLAIMS [received by the International Bureau on 04 April 2001 (04.04.01); original claims 18 replaced by new claims 17 (4 pages)] 1. A resistance device for controlling flow rate and reducing fluid pressure in a disc type of a cylindrical flow resistance module used in the control of fluids, wherein said resistance device comprises ; a plurality of annular coupling holes being aligned along the circumferential direction of discs, a first through hole pattern being defined by a plurality rectangular grooves and Tshaped through holes, wherein said Tshaped through holes being regularly aligned in a radial direction between a rectangular groove having a fluid inlet area at the inner circumference of a disc and a second rectangular groove having a fluid outlet area on the outer circumference of a disc, a second through hole pattern forming a predetermined angle with said first through hole pattern in a circumferential direction, and defined by a plurality of Tshaped rightangle turn flow path through holes regularly aligned in a radial direction, third and fourth through hole patterns forming a predetermined angle with said first and second through hole patterns in both circumferential directions, and defined by a plurality of rectangular holes regularly aligned in said radial direction ; wherein said four patterns each having angular symmetry are regularly arranged in said circumferential direction, wherein a plurality of the identical discs with said four patterns formed therein are combined together in an axial direction to form a disc stack, wherein four identical discs are individually rotated at a predetermined angle and combined together in an overlapping relationship to sequentially arrange said four patterns in said axial direction of said disc stack, thereby forming flow paths in said circumferential, radial and axial direction, wherein a series of said four discs are combined together in a regularly overlapping relationship to form said disc stack, thereby forming threedimensional tortuous flow paths, and wherein a constant rectangular area of the crosssection concerning said threedimensional tortuous flow paths therein is formed and a plurality of rightangle turns of said threedimensional tortuous flow paths fabricated by a stack module of said four discs is repeatedly formed ; and said threedimensional tortuous flow paths is characterized in that a plurality of vortex generating space having a shape of rectangular space for enhancing a local resistance of fluid flow prior to said rightangle turn being repeatedly formed so that said local resistance in connection with said vortex generating space can be effectively increased for controlling flow rate and reducing fluid pressure.
9. 2 The resistance device as claimed in claim 1, wherein a plurality of the vortex generating space through the threedimensional tortuous flow paths is characterized in that the vortex generating space having the confined space is formed respectively and consecutively along the radial, circumferential and axial direction of the disc stack.
10. 3 The resistance device as claimed in claim 1, wherein the crosssectional area of the threedimensional tortuous flow paths crossed by the discs varies as the discs are rotated at a predetermined angle and combined together in an overlapping relationship.
11. 4 The resistance device as claimed in claim 1, wherein the threedimensional tortuous flow paths have the crosssectional area repeatedly increased than the initial crosssectional area and reduced with the progress of the flow.
12. 5 The resistance device as claimed in claim 1, wherein the individual through holes of the discs have a round inner edge.
13. 6 The resistance device as claimed in claim 1, wherein the threedimensional tortuous flow paths has: the first through hole pattern defined by a plurality of Tshaped through holes being regularly aligned in the radial direction between a rectangular groove having a fluid inlet area at the inner circumference of the disc and a second rectangular groove having a fluid outlet area on the outer circumference of the disc, and the second through hole pattern forming a predetermined angle with the first through hole pattern in the circumferential direction, and defined by a plurality of Tshaped rightangle turn flow path through holes regularly aligned in the radial direction ; wherein the two patterns each having angular symmetry are regularly arranged in the circumferential direction, wherein a plurality of the identical discs with the two patterns formed therein are combined together in an axial direction to form a disc stack, wherein two identical discs are individually rotated at a predetermined angle and combined together in an overlapping relationship to sequentially arrange the two patterns in the axial direction of the disc stack, thereby forming a threedimensional tortuous flow paths in the circumferential, radial and axial direction, wherein a series of the two discs are combined together in a regularly overlapping relationship to form a disc stack, thereby forming the threedimensional tortuous flow paths in the confined space of the disc stack, and wherein a constant rectangular area of the crosssection concerning the threedimensional tortuous flow paths therein is formed and a plurality of rightangle turns of the threedimensional tortuous flow paths fabricated by as a module of two discs is repeatedly formed ; and the threedimensional tortuous flow paths is characterized in that a plurality of the vortex generating space having a shape of rectangular space for enhancing a local resistance of fluid flow prior to the rightangle turn being repeatedly formed so that the local resistance in connection with the vortex generating space is formed respectively and consecutively along the radial and circumferential direction of the disc module forming the threedimensional tortuous flow paths to effectively provide a local resistance in the confined space.
14. 7 The resistance device as claimed in claim 1, wherein the threedimensional flow paths have outlet through holes 471 and 472 of the first through hole pattern paired with through holes 571 and 572 for a groove forming flow path of the fourth through hole pattern with respect to through holes 511 for the both direction turning flow paths of the second through hole pattern, so as to constitute a plurality of outlets 481 and 482. Statement under Article 19 (1) We herein briefly explain the amendment and indicate the impact that such amendment might have on the description and the drawings. Explaining the Amendment : The original claims 1 to 2 are replaced by the amended claims 1 to 2, and the original claim 3 is cancelled. In addition, the original claim 7 is replaced by the amended claim 6 in the same manner of the amended claim 1. In the new set of amended claims 1 to 7, any relevance related to the citations in the Search Report are excluded by neglecting embodiment of the particular structure regarding three dimensional tortuous flow path in the citations. The specific embodiment of local resistance in the confined space related to the rectangular vortex generating space in connection with the typical shape of the three dimensional rectangular flow paths based on the series of hole patterns of the disc module is claimed in the amended claim 1. In the amended claim 1, a constant area of the rectangular crosssection through the three dimensional flow paths and the vortex generating space for the generation of local resistance is claimed in comparison with US 3, 780, 767 which is a different embodiment of vortex generation means related to a bottleneck shape of vortex generating embodiment located on the passage of the flow path. Furthermore, the amendment of claim 1 is established for clarifying the relevance of US 5, 819, 803 and EP 0 7 27 605 A1 related to a shape of rectangular through holes with right angle turn. Specifically, the structure of vortex generating space for increasing the local resistance effect in connection with the three dimensional flow paths is more clarifie in order to claim the totally different mechanism with the citations of Search Report for controlling flow rate and reducing fluid pressure. In the amended claim 2, the configuration of the rectangular vortex generating space consisting the three dimensional rectangular flow path along the radial, the circumferential and the axial direction of a cylindrical disc in the module are clearly specified. The original claim 3 is canceled due to the relevance of the general structure of three dimensional flow paths. In the amended claim 6, also the three dimensional tortuous flow path having the series of two discs without the axial formation of the rectangular vortex generating space is claimed as a modification of the structure regarding to the amended claim 1. The detail inventiveness of the new set of claims is described in the specification without varying the embodiment of the present invention. Indicating impact on Drawing and Specification No typical impact on the original drawing and specification is considered after the amendment.
Description:
Flow resistance device Technical Field The present invention generally relates to a fluid resistance device for controlling the velocity and pressure of a compressible or incompressible fluid and, more particularly, to a resistance device for controlling flow rate and reducing fluid pressure causing an extra-high pressure fluid to pass through a three-dimensional tortuous flow path with a vortex generating area formed in each tortuous section so as to effectively induce a local resistance to the fluid and decrease the flow rate and pressure to a desired level, with a minimum of noise, vibration, cavitation, abrasion, corrosion and blocking with foreign materials.

The present invention uses a cylindrical disc stack constituted by a plurality of circular discs axially stacked to control the flow of fluids between fluid inlet and outlet, the disc stack being made up of identical discs having a plurality of through holes arranged at the same angle and interval, the discs being individually rotated at a predetermined angle and combined together in an overlapping relationship. The four discs serially overlapping in the axial direction provide a plurality of three-dimensional tortuous flow paths defined by the through holes for flow paths, which through holes are formed in the discs. The through holes of the individual discs make a plurality of tortuous flow paths having a rectangular cross section such that two right-angle turning tortuous sections in two mutually perpendicular planes are iteratively arranged in order to provide high local resistance to the fluid at every tortuous section of the flow path, and that a vortex generating space is formed prior to the turn of the flow path at every tortuous section.

Also, the through holes are regularly aligned in a radial pattern with an angular symmetry in the circumferential and radial directions on the individual discs. That is, the tortuous flow path structure has three-dimensional flow paths formed by the four discs serially overlapping in the axial direction, and the flow paths form a plurality

of tortuous flow paths having a symmetry and regularly repeated in the circumferential and radial directions. The four discs constitute a unit module for forming a tortuous flow path and the three-dimensional flow paths are regularly iterated on the axis of the disc stack to provide a plurality of tortuous flow paths. Thus the fluid entering the inlet of the discs regularly arranged in the axial and inner circumferential direction of the disc stack passes through the regularly iterated flow paths sequentially formed in the radial, circumferential and axial directions along the three-dimensional flow path defined by the disc stack and gets out of the outlet of the first disc.

The present invention is directed to a high-performance resistance device for controlling flow rate and reducing fluid pressure that is usable under extreme conditions requiring an abrupt pressure drop under extra-high pressure and applicable to a pressure control valve, a flow control valve, a pressure relief valve, a back pressure control valve and a muffler that require a control of the flow rate, pressure and noise of the fluid, or similar fluid process systems for regulating the flow rate of the fluid.

Background Art Generally, a flow resistance module with orifice, labyrinth or tortuous flow paths is used to properly control the velocity and pressure of fluids and maintain long use time and best working status in the fields of industry requiring a precision of the control for fluid pressure and/or flow rate under extreme conditions such as extra-high pressure.

The flow rate generated at the flow resistance device is directly related to the total resistance coefficient determined by the pressure difference of the fluid between the front and rear ends, the fluid density, the flow path structure and the reynolds number. That is, the pressure drop of the flow resistance device is proportional to the total resistance coefficient, the density of the fluid and the square of the flow rate. <BR> <BR> <P> # # 2<BR> <BR> #P = #<BR> 2

where AP is the pressure drop of the fluid, t is the total resistance coefficient, p is the density of the fluid, and X is the flow rate. The pressure drop is dependent on the specific application requirements such that the total resistance coefficient increases with an increase in the local resistance at each tortuous section of the flow path. This allows the effective control of the flow rate and pressure and provides a more compact structure of the flow resistance device. The local resistance at each tortuous section is dependent upon the geometry of the tortuous section, such as a turning angle, a shape, a cross-sectional area, a roughness, a length of the tortuous sections, the orientation of the flow path formed by the tortuous sections, a use of which may provide relatively high local resistance and high total resistance coefficient as represented by the following relationship: <BR> <BR> <BR> <BR> <BR> I 1 = f (geometry)<BR> #P<BR> <BR> <BR> # 1 # = k#kReC1A# loc<BR> <BR> <BR> <BR> # # 2/2 where #1 is the resistance coefficient for one tortuous section, k# is the roughness coefficient of the flow path, kRe is the coefficient of the Reynolds number, Ci is the coefficient of the cross-sectional profile of the flow path, A is the coefficient of the turning angle, and oc is the resistance coefficient of a specific shape of the tortuous section.

Under the theoretical teaching, there have been proposed various flow resistance devices. Representative of such constructions are the following U. S. Patents: No. 5, 941, 281, No. 5, 819, 803, No.

4, 921, 014, No. 4, 617, 963, No. 4, 567, 915, No. 4, 407, 327, No.

4, 352, 373, No. 4, 279, 274, and No. 4, 105, 048.

The conventional flow resistance devices are mostly based on a series of discs or cylinders overlapped or stacked so as to provide a turn of the fluid or a variation of the cross-sectional area for a plurality of branched flow paths, thus dispersing the kinetic energy of the fluid and allowing a control of the pressure and flow rate in the devices. Specific labyrinth or tortuous flow resistance modules with a multipath and multistage flow path structure have also been proposed to increase the flow resistance at the individual flow paths in order to

minimize noise and cavitation.

It should be noted that U. S. Patent Nos. 4, 105, 048 and 5, 819, 803 provide a multipath and multistage flow resistance module effective in dispersing the kinetic energy at each flow resistance section with a tortuous flow path for turning the flow direction of the fluid. The present invention is also related to a device adapted for this field of the flow resistance module.

Especially, U. S. Patent No. 4, 105, 048 has a simple tortuous flow path with a relatively low local resistance to the fluid and thus provides a plurality of tortuous flow paths causing a velocity head loss as needed under a specific application requirement. In a case where two plates are used to form a flow path, there is required a separate baffle plate, which relatively increases the size of the flow resistance device and hence the volume and weight of the system equipped with the flow resistance device. This requires much materials and production costs relatively and a large space for installation of such a system. Also, U. S. Patent No. 5,819,803 chiefly uses abrupt reduction and expansion of the cross-sectional area of the flow path and thus locally causes an abrupt change of the flow velocity and pressure with problems of noise, vibration, corrosion or abrasion. In particular, as it is much difficult to maintain high purity of the fluid and prevent entrance of foreign materials in the industrial fluid control process, the area of the flow path whose cross-sectional area is abruptly reduced is possibly blocked with foreign materials (e. g., welding sludge, solid solution, corrosion products, etc.) contained in the fluid. Furthermore, a plurality of space or holes of different shapes and sizes are formed in at least two plates to provide a flow path, as a result of which the manufacture of the flow resistance device is extremely complicated and requires a relatively high cost.

A rise of the flow velocity in the fluid process system causes an increase erosion, corrosion and noise. It is known that water with a flow velocity of higher than 30 to 40 ft/sec incurs erosion in a system made from carbon steel. Much noise is increasingly generated as the flow rate of the fluid increases at a specific portion (e. g., a local position of orifices or valves) of the system. Such a rise of the

flow velocity lowers the pressure of a liquid and, if the pressure is reduced below the vapor pressure, causes vaporization of the liquid with flashing. To make matters worse, cavitation may occur when the pressure at the rear end is restored above the vapor pressure. Such a system has a serious problem related to noise, vibration, erosion and corrosion. It is therefore noted that an abrupt variation of the pressure and flow rate must be avoided in the flow resistance device operating under a specific application requirement.

Because the major noise source of the flow resistance device is the aerodynamic noise, the acoustic power of the noise is related to the mass flow rate, the pressure ratio of the upstream absolute pressure to the downstream absolute pressure, the geometric structure, and the physical properties of the fluid. It is known that a large pressure ratio at a specific portion causes a sonic flow or choked flow that generates much noise.

To solve the problems of such a fluid resistance device, Guy Borden ("Control Valves : Practical Guided for Measurement and Control", Instrument Society of America, 1998) suggests that the kinetic energy of the fluid at the outlet opening must be lowered in a range depending on the damage and noise standards. According to the IEC (International Electrotechnical Commission) Standard (IEC-534-8-3-1995,"Industrial-Process Control Valves, Part 8: Noise Considerations, Section 3: Control Valve Aerodynamic Noise Prediction Method"), an acoustic efficiency approach to lower the flow velocity of the fluid and a frequency shift approach to raise the noise frequency are used to reduce the noise. That is, acoustic efficiency, acoustic power and sound pressure level can be reduced by lowering the kinetic energy for the mass flow rate and the velocity of the fluid.

Also, a larger number of openings for the fluid to pass through shift the peak frequency of the noise towards the higher band, even above the audible noise frequency range with the transmission loss of the noise increased, thus reducing the noise.

A first technical teaching of the present invention is to provide a special tortuous flow path provided with a space at each rectangular tortuous section for absorbing an impulse caused by an abrupt

change of the flow rate at a portion that makes a turn with a tortuous flow path, and causing a vortex, and designed to effectively absorb the kinetic energy of the fluid without an abrupt change in the cross-sectional area of the flow path that otherwise causes a high pressure difference (also, referred to as pressure ratio related to noise generation). The three-dimensional flow path as described in U. S.

Patent No, 5, 819, 803 is a rectangular tortuous flow path simply by an abrupt variation of the cross-sectional area of the flow path, which has a simple structure forming a tortuous flow path with a pair of discs having a different shapes to induce a stream in the radial direction. Thus the present invention is to solve the problem related to noise, vibration, corrosion or abrasion caused by a sudden local change of the flow velocity and pressure. That is, the invention uses the thermodynamic and hydrodynamic characteristics of the fluid to form a vortex generating space before a turn of the flow direction at every tortuous section in the flow path and thereby provide a high local resistance coefficient.

It is demonstrated that the vortex generating space just before a turn of the flow in the tortuous section according to the present invention provides a resistance coefficient ts 1. 2 time higher than that of the tortuous section destitute of the vortex generating space. eS-SP2 1. 241 This is because the vortex of the fluid in the vortex generating space leads to a rotational energy loss of the fluid and causes the fluid passing through the vortex generating space to lose a kinetic energy as much as the vortex-generating rotational energy. With an abrupt pressure variation (rapid acceleration of the fluid) caused by an external factor, the vortex generating space serves as a buffering space to absorb the impulse and effectively reduces the kinetic energy of the fluid.

A second object of the present invention is to provide an efficient three-dimensional tortuous flow path structure constituted by a combination of regular patterns on discs and disc modules for forming a three-dimensional flow path, wherein the tortuous flow path

structure is branched into a plurality of outlet flow paths in order to effectively reduce the kinetic energy of the fluid, control the kinetic energy at the outlets to a desired level and shift the noise peak frequency to a higher level. In this connection, four discs constitute a unit module for forming a tortuous flow path such that the fluid is caused to flow in both radial and circumferential directions of the discs. That is, the present invention provides a circumferential flow path as well as a radial flow path on a single plane in order to reduce the rotational kinetic energy of the fluid in the circumferential direction directed to the outlet according to the structural characteristic of the disc, and radial patterns regularly arranged in a repeated manner in the circumference and radial directions with angular symmetry on the individual discs in order to form a three-dimensional tortuous flow path, wherein four discs with the patterns are serially stacked to provide a three-dimensional tortuous flow path that forms a plurality of tortuous flow paths having a highly symmetric structure. This highly symmetric tortuous flow path according to the present invention effectively causes a local resistance even at a confined space and provides a stable module in the axial and circumferential directions with mutual attenuation of vector components of the fluid imposed on the disc of the unit module. The flow path constituted by the above-stated patterns has a multipath structure in order to further reduce the flow velocity at the outlets of the resistance module and shift the peak frequency to a higher level.

Disclosure of the Invention Based on the teachings, the present invention provides a high-performance resistance device for controlling flow rate and reducing fluid pressure with a plurality of identical discs having a plurality of through holes aligned at the same angle and intervals, the discs being individually rotated at a predetermined angle and combined together in an overlapping relationship, thereby facilitating the manufacture of the resistance device at a relatively low cost. Four discs serially overlapping in the axial direction form a plurality of tortuous flow paths by way of through holes for the flow paths formed

in the discs, and each flow path has two right-angle turning sections in two mutually perpendicular planes and a vortex generating space just before each turn of the flow path for every tortuous section, to effectively provide a local resistance in a confined space. This makes it possible to effectively control flow rate and fluid pressure under an extra-high pressure and eventually manufacture a miniaturized flow resistance device as adaptable to a general valve or equipment.

The present invention also provides a flow resistance device having a relatively large cross-sectional area from inlet to outlet of the flow path defined by the discs without an abrupt reduction of the cross-sectional area lest the flow rate and the pressure of the fluid should be varied abruptly, thereby reducing noise, vibration, erosion and corrosion, and preventing the flow path choked with foreign materials contained in the fluid.

Furthermore, the present invention allows the performance of the device easily changed by varying the design characteristic of the disc depending on the specific application requirement. That is, many modifications are readily achieved in the aspect of design adequate to the characteristic of the fluid simply by changing the thickness, inner and outer diameters and area of the individual discs, the cross-sectional area and roughness of the flow path formed by the through holes of the discs, the number of turns of the flow paths, and the number of discs.

Brief Description of Drawings Fig. 1 is a partial cross section of a valve equipped with a resistance device for controlling flow rate and reducing fluid pressure ; Fig. 2a is a schematic view of a three-dimensional unit tortuous flow path structure formed by four discs ; Fig. 2b is a schematic view of a three-dimensional tortuous flow path structure formed by four discs to provide outlets ; Fig. 3a is a plan view of a disc forming the flow path structure shown in Fig. 2a ; Fig. 3b is a plan view of a disc forming the flow path structure shown in Fig. 2b ;

Fig. 4 is a perspective view showing a combination of a plurality of discs and two end plates constituting the resistance device for controlling flow rate and reducing fluid pressure ; Fig. 5 is a perspective view of the assembled resistance device for controlling flow rate and reducing fluid pressure; Fig. 6a is a plan view of a disc shown in Fig. 3a, which has round-edged through holes ; and Fig. 6b is an enlarged view of the edges of the through holes shown in Fig. 6a.

Best Mode for Carrying Out the Invention Hereinafter, the construction and operation of the present invention will be described below in detail as follows.

Referring now to Fig. 1, there is illustrated a typical valve 1 according to the present invention, comprising a valve body 2, a bonnet 3, a plug 4, a stem 5, a seat ring 6, and a flow resistance device 7.

Such a typical valve 1 operatively allows a predetermined amount of a fluid to flow according to the axial position of the plug 4 with respect to the flow resistance device 7 and the seat ring 6, such that the fluid travels from an inlet 11 to an outlet 12 or, reversely, from an inlet 13 to an outlet 14. The valve is generally configured to provide advantages attendant upon the characteristic of the fluid, i. e., an incompressible fluid such as liquid is allowed to flow from the outside of the flow resistance device 7 to the inside of it associated with the plug 4, while a compressible fluid such as vapor flows from the inside of the flow resistance device 7 associated with the plug 4 to the outside of it.

The present invention pertains to a resistance device for controlling flow rate and reducing fluid pressure in association with the flow resistance device 7 disposed between inlets 11 and 13 and outlets 12 and 14 in the above-stated valve 1 or the like. The flow resistance device 7 comprises discs 15 and end plates 8 and 9 stacked and combined together by bolt 10 and nut 16. As in usual cases, the flow resistance device 7 is closely brought onto the seat

ring 6 with the bonnet 3. If necessary, a plurality of discs 15 and end plates 8 and 9 can be combined together with welding or using a pin, instead of bolts 10 and nuts 16.

The flow resistance device 7 mostly used under extreme conditions such as high pressure and temperature has the inlets 11 and 13 under extremely high pressure, or a high pressure difference between the inlets 11 and 13 and the outlets 12 and 14. In such conditions, the flow resistance device 7 is provided with a tortuous flow path structure in order to reduce the velocity and pressure of the fluid to a desired level.

Fig. 2a is a schematic view of the flow path structure formed by four discs in the flow resistance device 7 show in Fig. 1.

As may be seen in Fig. 2, fluid enters the flow resistance module from an inlet path area having a T-shaped right-angle turn flow path 21 of the first disc and turns a first right angle to pass into a vortex generating space 30 which is in a line with the flow direction.

The fluid makes a second right-angle turn to pass into a vortex generating space 31 formed between the adjoining faces of the T-shaped right-angle turn flow path 21 of the first disc and the second disc, and enters the second disc along a through hole 26 formed between the adjoining faces of the T-shaped right-angle turn flow path 21 of the first disc and a T-shaped right-angle turn flow path 22 of the second disc. Thereafter, the fluid makes a third right-angle turn to enter a vortex generating space 32 formed between the adjoining faces of the T-shaped right-angle turn flow path 22 of the second disc and a groove forming flow path 23 of the third disc ; a fourth right-angle turn to enter a vortex generating space 33 of the T-shaped right-angle turn flow path 22 of the second path ; and a fifth right-angle turn to enter a vortex generating space 34 formed between the adjoining faces of the T-shaped right-angle turn flow path 22 of the second disc and the first disc. From the second disc, the fluid passes back into the first disc along a through hole 28 formed between the adjoining faces of the T-shaped right-angle turn flow path 22 of the second disc and an outlet flow path 25 of the first disc. The fluid then makes a sixth right-angle turn to pass into a

vortex generating space 35 formed between the adjoining faces of the outlet flow path 25 of the first disc and a groove forming flow path 24 of the fourth disc, and enters the outlet flow path 25 of the first disc.

The flow path structure has an iterative alignment of two torturous sections that cause multiple right-angle turns in two mutually perpendicular planes such that the fluid entering the first disc makes six right-angle turns at the torturous sections each having vortex generating spaces 30, 31,32,33,34 and 35 until it returns to the first disc through the three-dimensional flow paths. It is thus possible to effectively reduce the kinetic energy by the energy losses caused at multiple vortex formations and right-angle turns.

Fig. 2b is a schematic view of a three-dimensional tortuous flow path structure formed by four discs to provide outlets. This structure may be combined with the tortuous structure of Fig. 2a as a disc structure shown in Fig. 3b and adapted for the final passage from which the fluid is exhausted. Such a structure in combination with that of Fig. 2a may provide a tortuous structure of various flow path patterns depending on the hydrodynamic characteristic of the fluid. The tortuous structure of Fig. 2b is also the same technical component as that of Fig. 2a, by which the fluid passing through the vortex generating spaces 30, 31, 32, 33, 34,35,36 and 37 is exhausted from two symmetrical outlets so as to reduce the kinetic energy of the fluid at the outlets.

A series of the above-stated flow paths sterically iterative make the best use of a given volume of the resistance device and provide high flow resistance to the flowing fluid without an abrupt change of the flow area in the flow path at each tortuous section. It is thus possible to effectively control the velocity and pressure of the fluid under extremely high fluid pressure, prevent the inside of the path choked with foreign materials and effectively reduce the fluid pressure, as a result of which a compact structure of the device can be provided.

Within the acceptable range of the variations in the pressure and velocity of the fluid, the through holes 26 and 28 formed between

the adjoining faces of the flow paths 21 and 25 of the first disc and the flow path 22 of the second disc may be arranged in a staggered alignment in order to reduce the flow area of the fluid, thereby providing a multi-turn labyrinth for the fluid and hence high flow resistance. This structure can be adapted for a flow resistance device containing no foreign material.

Although the flow path structure of Fig. 2a or 2b is illustrated to have a constant cross-sectionai area from the inlet path to the outlet, the flow path, especially, for a compressible fluid such as gas may have the cross-sectional area increasing from Ao at the inlet path to Ai at the outlet in order to allow expansion of the volume due to a pressure drop or for special purposes. The invention is also advantageous in that the cross-sectional area of the tortuous flow path can be increased by increasing the width B of the flow path in the radial direction of the disc and reducing the width A of the flow path in the circumferential direction of the disc to provide higher flow resistance, in order to make the best use of the space in the radial direction of the disc. In this case, it should be noted to make the cross-sectional areas of flow paths larger than the initial cross-sectional area Ao lest the flow path be choked with foreign materials.

The above-stated resistance device for controlling flow rate and reducing fluid pressure may be configured to provide a flow path from two discs under certain conditions. That is, the flow path structure may be provided with an iterative combination of the T-shaped right-angle turn flow path 21 of the first disc and the T-shaped right-angle turn flow path 22 of the second disc such that the fluid entering the inlet flow path 36 is exhausted from the outlet flow path 37.

Figs. 3a and 3b are plan views of a disc 15 forming the three-dimensional flow path structures shown in Figs. 2a and 2b, respectively. The structure of Fig. 3a causes the fluid to enter an inlet 43 of the disc 15 from the center of the fluid resistance device 7 and get out of the disc 15 through an outlet 48 along the tortuous flow paths formed in the radial, circumferential and axial directions of the

disc 15, while the structure of Fig. 3b cause the fluid entering the disc 15 to be exhausted to the outside from the disc 15 through two outlets 48-1 and 48-2 along the respective tortuous flow paths.

Contrarily, if the flow path structures of Figs. 2a and 2b are formed from the outside to the center of the disc 15, the fluid enters the disc 15 from the outside and gets exhausted to the central space of the disc 15 along the tortuous flow paths of the disc 15.

Referring to Fig. 3a, each disc 15 has an inlet through hole 44 for the T-shaped right-angle turn flow path with six inlets 43, and an outlet through hole 47 with six outlets 48, as a result of which four discs 15 form a tortuous flow path structure shown in Fig. 2a in the flow resistance device according to the present invention that makes three flow path structures and provides 18 tortuous sections for the right-angle turns of the fluid. The flow path structure may determined to satisfy the characteristic requirements of the fluid in consideration of the number of flow path forming through holes for the respective flow paths, the cross-sectional area of the through holes, the distance between the tortuous sections for right-angle turns, the surface roughness of the flow path, and the edge profile of the through holes.

The disc 15 has an inner perimeter 41 and an outer perimeter 42. With respect to an angle of the disc 15, the inner perimeter 41 is provided with the inlet 43 for forming the T-shaped right-angle turn flow path 21, through holes 45 and 46 for the second and third T-shaped right-angle flow paths adjacent to the inlet 43 in the radial direction of the disc 15, and the outlet through hole 47 providing the outlet 48 adjacent to the through holes 45 and 46. This first through hole pattern is configured to align the four discs for forming the three-dimensional unit tortuous flow path of Fig. 2a at a through hole position 62, when the four identical discs are individually turned by a predetermined angle in the counter-clockwise direction and stacked.

With respect to a predetermined angle in the clockwise direction of the first through hole pattern, the inner perimeter 41 of the disc 15 is provided with a T-shaped right-angle turning through hole 49, a through hole 50 for the second T-shaped right-angle turn flow path adjacent to the through hole 49 in the radial direction of the

disc 15, and a through hole 51 for the third T-shaped right-angle turn flow path adjacent to the though hole 50 in the radial direction of the disc 15. This second through hole pattern is configured to align the four discs for forming the three-dimensional unit tortuous flow path of Fig. 2a at a through hole position 63, when the four identical discs are individually turned by a predetermined angle in the counter-clockwise direction and stacked.

With respect to a predetermined angle in the clockwise direction of the second through hole pattern, the inner perimeter 41 of the disc 15 is provided with a through hole 52 for the groove forming flow path, and second and third through holes 53 and 54 for the groove forming flow path adjacent to the through hole 52. This third through hole pattern is configured to align the four discs for forming the three-dimensional unit tortuous flow path of Fig. 2a at a through hole position 64, when the four identical discs are individually turned by a predetermined angle in the counter-clockwise direction and fixedly stacked.

With respect to a predetermined angle in the clockwise direction of the second through hole pattern, the inner perimeter 41 of the disc 15 is provided with a through hole 55 for the groove forming flow path, a second through hole 56 for the groove forming flow path adjacent to the through hole 55, and a third through hole 57 for the groove forming flow path adjacent to the through hole 56. This fourth through hole pattern is configured to align the four discs for forming the three-dimensional unit tortuous flow path of Fig. 2a at a through hole position 65, when the four identical discs are individually turned by a predetermined angle in the counter-clockwise direction and fixedly stacked.

Thus the four through hole patterns are iteratively formed by a predetermined angle in the clockwise direction of the disc to provide a regular alignment having an angular symmetry in the circumferential direction.

The term"predetermined angle"as used herein refers to a defined angle between the two adjacent through hole patterns in the circumferential direction of the disc 15 and may be (360/4n) °, wherein

n represents the number of inlets formed in one disc 15.

To lower the kinetic energy of the fluid at the outlets as compared to the case of Fig. 3a, the disc of Fig. 3b has two outlet through holes 47-1 and 47-2, a through hole 51-1 for the right-angle turn flow path, and two through holes 57-1 and 57-2 for the groove forming flow path for every through hole pattern, instead of the outlet through hole 47, the through hole 51 for the T-shaped right-angle turn flow path, and the through hole 57 for the groove forming flow path. The disc may further has at least two outlets for every flow path in a similar way so long as the space in the circumferential direction of the disc permits.

Similarly, the identical discs 15, each having first and second through hole patterns only regularly in the circumferential direction, may be assembled axially to implement a resistance device for controlling flow rate and reducing fluid pressure. That is, the two through hole patterns are regularly arranged with an angular symmetry and a plurality of identical discs containing the through hole patterns are combined together in a regularly overlapping relationship into a disc stack to provide an arrangement of tortuous flow paths in the axial direction of the disc stack.

Formed in the disc 15 are a bolt (or pins as will be the same hereinafter) fastening hole 58 for fastening the discs together at a predetermined distance from the center of the disc and at a position of the intermediate angle of the flow path forming through hole patterns, and bolt fastening holes 59, 60 and 61 separated from the bolt fastening hole 58 at a predetermined angle in the clockwise direction. These bolt fastening holes are formed at four positions at every right angle separated from the center of the disc at a predetermined distance. The identical discs are stacked, individually rotated at a predetermined angle in the counter-clockwise direction as illustrated in Fig. 4 and combined together by four bolts. To fasten the discs together with three bolts, the boit fastening holes 58, 59, 60 and 61 are provided at three positions separated at a predetermined distance from the center of the disc and at intervals of 120°. Those bolt fastening holes are unnecessary when the discs are combined

together by another method such as welding instead of using bolts.

Fig. 4 is a perspective view showing a combination of a plurality of discs 15 and two end plates 8 and 9 constituting the resistance device for controlling flow rate and reducing fluid pressure.

In the resistance device, the end plates 8 and 9 identical to each other are the same as the disc 15 in regard to the size of the central hole and the outer diameter. The end plate 8 has four bolt fastening holes 83,84,85 and 86 every right angle at the same position of the bolt fastening holes of the disc 15 in order to bolt a plurality of the discs together.

For simplicity, it is illustrated in Fig. 4 that six identical discs 15 of Fig. 3a are combined with the end plates. Six discs 71, 72, 73, 74, 75 and 76 with through holes of various shapes equally have through holes as the disc 15 of Fig. 3a.

The discs 71,72,73,74,75 and 76 are individually rotated in the counter-clockwise direction by a predetermined angle and combined together as described in Fig. 3a, which procedure will be described in detail as follows. Based on a bolt fastening hole 89 of the lower end plate 9, bolt fastening holes 61, 58, 59, 60, 61, 58 and 86 of the first to sixth discs 71,72,73,74,75 and 76 and the upper end plate 8, respectively, are fastened in a line with bolts. Then, the other three bolt connections are provided in the same way. Instead of using bolts, the discs and the end plates may be combined together by welding as described in Fig. 1.

As the plural discs are stacked, the flow path forming through holes of the individual discs are brought in close contact with the flow path forming through holes and no-through-hole surfaces of their adjacent discs so as to provide the flow path structure of Fig. 2a or 2b, which makes up a resistance device for controlling flow rate and reducing fluid pressure with a plurality of three-dimensional tortuous flow paths. That is, the identical discs 15 with four regular through hole patterns of Fig. 3a or 3b to form the unit tortuous flow path structure of Fig. 2a or 2b are individually turned at a predetermined angle and stacked in overlapping relationship in the form of a disc stack, so that the four through hole patterns are sequentially arranged

in the axial direction of the disc stack to provide three-dimensional tortuous flow paths in the circumferential and radial directions of the disc. As the four disc are regularly overlapped with one another into a disc stack, the three-dimensional tortuous flow paths are also provided in the axial direction of the disc stack.

Fig. 5 is a perspective view of the assembled resistance device for controlling flow rate and reducing fluid pressure.

As illustrated in Fig. 4, the end plates 8 and 9 and the discs 15 are combined together by four bolt fastening nuts 91, 92,93 and 94, and a plurality of flow path holes 95 are uniformly distributed in every disc so that fluid passing into any one disc is exhausted from that disc eventually.

The resistance device of Fig. 5 has a plurality of flow path structures separated in an array at a predetermined distance from one another and at a predetermined angle in the discs 15 of the same thickness, so as to provide a constant discharge rate of the fluid for every disc under any condition. Also, varying the thickness of the individual discs 15 may differentiate the discharge rate of the fluid passing through the discs.

Fig. 6a is a plan view of a disc shown in Figs. 3a and 3b that has round-edged through holes, and Fig. 6b is an enlarged view of the edges of the through holes shown in Fig. 6a. Although it is illustrated in Figs. 3a and 3b that the edges of the flow path forming through holes 44, 45,46,47-1,47-2,49,50,51,52,53,54,55,56, 57,57-1 and 57-2 are processed to have a rectangular edge with a special processing machine such as a laser machine, they may also be processed to have a round edge with a milling machine or a computer numerical control (CNC) machine. The round-edged through holes are so preferable as to facilitate the manufacture without a significant effect on the performance of the resistance device.

Industrial Applicability The present invention is to solve the afore-mentioned drawbacks of the conventional flow resistance modules and provide a high-performance resistance device for controlling flow rate and

reducing fluid pressure easily designed with identical discs at a relatively low production cost. This flow rate and the performance of the flow resistance device are simply changed by varying the design characteristic of the individual discs under a specific application requirement.

As described above, the resistance device for controlling flow rate and reducing fluid pressure according to the present invention causes the fluid of extremely high pressure to have the flow rate and pressure reduced to a desired level and has a plurality of fluid outlets to decrease the kinetic energy of the fluid and shift the peak frequency for the noise to a higher frequency level, with a minimum of noise, vibration, cavitation, abrasion, corrosion and blocking with foreign materials in the flow resistance device and equipment using the same.