Patent Application
20150118088
The invention relates to a valve for regulating the fluid pressure and/or the fluid flow in a fluid distribution and transportation network. In particular the invention relates to such a valve comprising a stator and a rotor arranged in the stator. The valve may be used to decrease the fluid pressure and/or flow, i.e. to produce a negative differential pressure or flow between the inlet port and the outlet port of the device by extracting power from the fluid. The rotor may be connected to a braking means for causing a decrease of the fluid pressure or the fluid flow.
There often exists a need for regulating the fluid pressure and/or the fluid flow in fluid distribution networks. An example of such a fluid distribution network is a water distribution system used in cities for distributing drinking water from a central reservoir to a plurality of households and other water consumers. Such networks or systems typically comprise one or several main water lines or conduits that convey water from a reservoir or a pump station to different zones of the network. Each zone normally comprises a secondary water line or conduit which conveys water to different areas in the zone. In each such area a consumer distribution line supplies drinking water from the secondary conduit to each individual consumer within the area. Typically the pressure in the main conduits is around 20 bar, whereas the pressure in the individual consumer lines is kept at around 3 bar. Therefore the distribution network often comprises pressure reducing means which normally are arranged at the junctions between the main and secondary conduits and/or between the secondary conduits and the consumer lines. The pressure reducing means may however also be arranged within the main, secondary or the consumer line conduits. In other systems there may be arranged additional intermediate water line conduits operating at different pressures between the main water line and the consumer distribution lines. Traditionally the pressure reducing means are constituted by conventional pressure valves, which often arc spring loaded or controlled by a pilot pressure.
In order to be able to utilize the energy of the fluid, it has been suggested to provide the pressure reducing valve in such a water distributing network with a turbine which is arranged to capture energy which is released during pressure reduction. U.S. Pat. No. 6,824,347 B2 discloses such valve.
Even though the previously known valves may be utilized at and adapted for harvesting of energy while regulating the fluid pressure and/or the fluid flow in different types of fluid distribution networks, there still remain disadvantages of the known arrangements. A major disadvantage of the previous known valves is the comparatively low efficiency, i.e. that a comparatively large portion of the energy carried by the fluid is lost in the valve, before conversion to useable energy, such as electricity. A further disadvantage is a considerable wear of the constructional parts, especially at high fluid pressures. Additionally, the known valves need to be specially designed and constructed for each field of application and nominal load.
It is therefore an object of the present invention to provide an enhanced valve for regulating the fluid pressure and/or the fluid flow in a fluid distribution network.
It is another object to provide such a valve which allows for energy production at a comparatively high efficiency.
It is a further object to provide such a valve at which the wear of constructional parts may be kept low and the reliability in service high.
Another object is to provide such a valve which may be constructed with comparatively thin or light constructional parts and still be able to withstand comparatively high fluid pressures and flows.
Still another object is to provide such a valve which readily allows for a modular construction whereby the device may be easily constructed and assembled for different applications by utilizing a comparatively low number of standardized components in different combinations.
These and other objects are provided by a valve as set out in the preamble of claim 1, which valve comprises the special technical features specified in the characterizing portion of the claim.
The valve is intended for regulating the fluid pressure and/or the fluid flow in a fluid distribution network. It comprises a stator defining an interior space; at least one inlet port and at least one outlet port, which inlet port and outlet port are arranged for being connected to a fluid duct of the fluid distribution network; and a rotor. The rotor is arranged rotatable about a rotational axis in the interior space and provided with a rotor core and a number of vanes which are movable in relation to the core and which rotor, in sealing relation with the stator, upon rotation, continuously divides the interior space into at least two mutually separated chambers. Each chamber comprises an inlet opening and an outlet opening. In accordance with the invention, the valve comprises at least one inlet channel which connects the at least one inlet port with at least one inlet opening of each of said at least two chambers and at least one outlet channel which connects at least one outlet opening of each of said at least two chambers with the at least one outlet port.
The stator and the rotor thus define a number of chambers, each of which extends axially and circumferentially around the rotor. At some embodiments sealing between the rotor core and the stator may define the chambers. It is however also possible that the vanes in sealing relation with the stator define the chambers. The terms sealing relation and sealing contact are used herein to define a relation between the rotor and the stator where a substantial sealing for the fluid occurs. The rotor core and/or the vanes may be in physical contact with the stator. It is however also possible that the core and/or the vanes are arranged with some play to the stator. At such embodiments a fluid film will be formed between the core and/or vanes and the stator, which fluid film contributes to provide the sealing. At both alternatives some fluid leakage may occur. Such a fluid leakage is however comparatively small such that a substantially sealing occurs, which substantial sealing allows for that the energy of the fluid flow may be utilized for driving the rotation of the rotor. As will be described more in detail below, an important advantage of the present invention is that the invention provides for that the internal fluid leakage may be kept comparatively small whereby the power efficiency of the valve is enhanced
An inlet opening and an outlet opening for each chamber are arranged in the stator. The inlet openings may be arranged at a first circumferential end of each chamber and the outlet openings may be arranged in the stator at the opposite circumferential end of the respective chamber. Alternatively, the inlet and outlet openings may be arranged in end walls of the stator. In both cases, each chamber extends between the respective inlet opening and outlet opening arranged in the stator. Upon rotation of the rotor, the rotor core or at least one vane is always in sealing contact with the stator between each chamber. In this way all chambers are mutually separated from each other. Additionally, at least one vane is always in sealing contact with the stator between the inlet and outlet of each chamber. The fluid pressure prevailing in the upstream duct thus acts on the vane in each chamber and drives the rotor to rotation. By braking the rotor, energy is harvested from the fluid, whereby the pressure and/or the flow at the outlet is lower than the pressure and/or the flow at the inlet.
By means of the at least one inlet channel, which connects an upstream portion of the conduit to each chamber and the at least one outlet channel which connects each chamber with a downstream portion of said conduit, essentially the same pressure will prevail in each chamber. Hereby a number of advantages are achieved. The pressure equilibrium entails for that the rotor is at least essentially balanced in a radial direction. Hereby, the radial forces acting on the rotor's bearings will be reduced, which in turn results in reduced bearing friction. By this means the efficiency of the device is increased at the same time as the wear of the bearings is reduced and the service life increased. The radial balancing of the rotor also reduces the radial deflection of the rotor. This also entails for a reduced wear of the rotor and the surrounding housing. Additionally the reduced radial deflection allows for that the rotor and thereby the entire device may be constructed with a comparatively large axial extension in relation to the radial strength of the rotor and its supporting components. The inventive balancing of the rotor also reduces the internal leakage, which in previously known arrangements is caused by the comparatively large clearances between the stator and the rotor needed for compensating for the above mentioned radial deflection of the rotor. At the balanced rotor according to the invention, where the differential pressure acts essentially equally on all surfaces around the rotor, the reduced deflection of the rotor makes it possible to design the valve with essentially smaller clearances between stator and rotor, than what has been possible hitherto. This reduces internal leakage which in turn contributes greatly to an increased efficiency of the valve. It is further possible to construct the device with an increased capability to withstand high fluid pressures and flows in relation to the amount and specific strength of the material used for the load carrying components of the device. In this way the manufacturing costs may be reduced.
The circumferential extension of each chamber about the rotor is preferably made essentially equal. In this way, the product of the fluid pressure and the fluid area acting on the rotor, i.e. the radial force acting on the rotor, for each chamber is readily kept the same. Hereby radial force balancing of the rotor is readily achieved.
The interior space may be divided into an even number of chambers. Alternatively, the number of chambers may be odd. At embodiments with an odd number of chambers it may by possible to reduce pressure pulsations and vibrations in the stator and the rotor. An odd number of channels may also allow for an enhanced capacity of the valve.
The inlet openings may be arranged in pairs radially opposite to each other and the outlet openings may be arranged in pairs radially opposite to each other. This further entails for an equilibration of the radial forces acting on the rotor and facilitates manufacturing of the device.
The inlet channels and the outlet channels may be annular and extend circumferentially around the interior space. This entails for an axially space saving construction whereby the dimensions of the device may be kept comparatively low. Additionally, such an arrangement also provides pressure balancing between the fluid inside the stator and the fluid in the channels, which may reduce the requirements for strength and thus material selection and/or thickness of the material forming the stator.
Each inlet channel may be connected to a respective inlet opening of two chambers and each outlet channel connected to a respective outlet opening of two chambers. When the total number of chambers is even, this entails for that the number of inlet and outlet channels may be kept equal to the number of chambers divided by two, irrespective of how many chambers are arranged in the device. This facilitates a modular design and construction of the device, which in turn enhances the possibility to readily adapt the device for different applications.
The device may comprise a number of inlet channels and outlet channels, which are arranged one after the other along the axial extension of the rotor. This entails for a better distribution of the flow into the chambers. It also provides an enhanced axial distribution of the radial fluid forces acting on the rotor. Hereby the wear of the rotor and its supporting components is reduced further, especially at applications where the device comprises a comparatively large number of chambers.
By such an arrangement one after the other of an equal number of inlet channels and outlet channels, the axial force distribution may be further enhanced.
The inlet channels and outlet channels may further be arranged alternately one after the other along the axial extension of the rotor. Such an alternate arrangement enhances the axial distribution of radial forces even further.
The inlet channels and outlet channels may preferably be formed of essentially identical parts. Hereby the modular design and construction for adapting the device to different applications is greatly enhanced. This in turns result in an economical and efficient design and manufacturing of highly application adapted devices.
At least one inlet channel or outlet channel may be formed of a radially inner part exhibiting at least one communication opening and a radially outer part exhibiting an inlet port or an outlet port respectively. By this means it is possible to freely choose and arrange the direction of the inlet and/or outlet ports. This in turn entails for a space saving installation of the valve e.g. in existing water distribution networks where the available space may be limited.
When at least one inlet or outlet channel comprises radially inner and outer parts, the radially inner and outer parts may be circumferentially slidable in relation to each other. By this means the relative position between the inlet or outlet ports and the corresponding communication opening may readily be chosen and varied freely. By such a slidable arrangement the configuration of the inlet and outlet ports as well as the communications openings may further be set up and adapted on site at or even after installation of the vale. This entails for a further increased flexibility e.g. when arranging the valve in narrow spaces.
The radially inner part may further be circumferentially slidable in relation to the stator. This entails for an even greater flexibility in adapting the configuration of the inlet an/or outlet channels e.g. at or after installation of the valve.
The vanes may be arranged movable in relation to the core such that they define a respective active area which is parallel with the axial and radial directions of the rotor and which areas vary with the movement of the respective vane in relation to the core. This allows for that the vanes exhibit a varying stroke. The vanes and the rotor core are preferably arranged such that each vane has a minimum stroke immediately before and after having passed the inlet and outlet openings respectively and a maximum stroke in the operating space between the inlet and outlet opening of each chamber. Hereby, the counteracting forces generated by the fluid and acting on the vanes in a direction opposite to the rotational direction of the rotor may be reduced and minimized. This in turn entails for a reduction of losses and an increased efficiency of the device.
The vanes are preferably arranged such that the respective active area or the stroke, upon rotation of the rotor, is essentially zero at a position of the vane immediately before reaching the inlet opening and immediately after passing the outlet opening of each chamber. Hereby, the reduction of losses and increase of efficiency is enhanced even further.
The vanes may be arranged radially slidable in relation to the rotor core. Hereby, the desired variable stroke of the vanes is readily achieved in a space saving manner by means a comparatively low number of moving parts. This embodiment also allows for that the rotor may be rotated in any desirable direction.
Alternatively, the vanes may be arranged pivotal about pivotal axes which extend in parallel with the rotational axis of the rotor, in relation to the rotor core. This also readily allows the vanes to exhibit the desired variable stroke. Embodiments with pivotal or hinged vanes may entail certain advantages such that; a possibility to design the rotor stronger with a lower resulting deflection and easier machining; enhanced sealing between vanes and rotor as well as between vanes and stator and reduced wear of the vanes.
The rotor of the valve may be mechanically connected to a machine for utilizing energy extracted by the rotor from the fluid flow to drive said machine. Hereby, the device may be utilized both as a pressure and/or flow regulating valve and as a means for re-utilization of energy. Naturally this entails for great economical and environmental advantages in many applications involving fluid pressure reduction or fluid flow reduction.
The valve may comprise a generator which is mechanically connected to the rotor for braking the rotational movement of the rotor and generating electrical power. Hereby, the device may be utilized both as a pressure and/or flow regulating valve and as a means for generating electrical power. This also entails for great economical and environmental advantages in many applications involving fluid pressure reduction or fluid flow reduction.
Said machine may comprise a pump turbine which is mechanically connected to the rotor for braking the rotational movement of the rotor and increasing the pressure and/or the flow of a fluid flow through said machine. By this means the inventive vale may be efficiently used for supplying energy to a fluid flow. This fluid flow may be separated from the fluid flow which runs through the inventive valve or it may form part of a fluid flow system which also incorporates the fluid flow through the valve.
Further objects and advantages of the device according to the invention will appear from the following detailed description of embodiments and from the appended claims.
Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to “a/an/the element, apparatus, component, means, step, etc.” are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
The invention is now described, by way of example, with reference to the accompanying drawings, in which:
a and 4b is a perspective view and a cross sectional view respectively of a portion of a stator core comprised in the valve shown in
a and 10b are perspective views, partly in section of certain components comprised in the valve shown in
The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout the description.
The stator core 11 and the outer wall 12 further define an inlet channel 17. The inlet channel 17 connects the inlet port 15 with a first 17a and a second 17b inlet opening which are arranged through the stator core and which connects the inlet channel with the interior space 14. The inlet openings 17a, 17b are arranged radially opposite to each other. Correspondingly the stator core 11 and the outer wall 12 also define an outlet channel 18. The outlet channel 18 connects the outlet port 16 with a first 18a and a second 18b outlet opening which are arranged through the stator core and which connects the outlet channel with the interior space 14. The outlet openings 18a, 18b are arranged radially opposite to each other and angularly displaced about 90° with respect to the inlet openings 17a, 17b.
As best seen in
A rotor 20 is rotatably arranged in the interior space 14 of the stator 10. The rotor comprises a rotor core 21 which is fixed to an axle 22. A number of vanes 23 are pivotally fixed to the rotor core 21 such that the may pivot about a respective pivotal axis which extends in parallel with the rotational axis and the axle 22 of the rotor. At the illustrated embodiment the rotor 20 comprises eight vanes 23 which are evenly distributed over the circumference of the rotor core 21. Each vane 23 extends over essentially the entire length of the rotor core 21 and the interior space.
The rotor 20 as illustrated in
As best seen in
As also best seen in
Each chamber 14a, 14b is divided into an upstream portion 14a′, 14b′ or high pressure portion and a downstream portion 14a″, 14b″ or low pressure portion. The upstream portion 14a′, 14b′ of each chamber 14a, 14b is separated from the corresponding downstream portion 14a″, 14b″ by means of the vane 23b presently being arranged between the inlet opening 17a, 17b and the outlet opening 18a, 18b of the respective chamber 14a, 14b. In use it is the differential pressure between the upstream portion 14a′, 14b′ and the downstream portion 14a″, 14b″ acting on said vane 23b which drives the rotor to rotation, in the anti-clockwise directions as seen in
As indicated above both inlet openings 17a and 17b are in communication with the same inlet channel 17 and the same inlet port 15. Thus the same pressure will prevail in both chambers 14a and 14b, upstream of the vane 23b arranged between the inlet 17a, 17b and outlet 18a, 18b openings of the respective chamber. Additionally, the outlet openings 18a, 18b are in communication with the same outlet channel 18 and the same outlet port 16. Thus the pressure which prevails downstream of the vane 23b arranged between the inlet openings 17a, 17b, and the outlet openings 18a, 18b will also be essentially the same for both chambers 14a, 14b. In other words, the pressures which prevail in portions 14a′ and 14b′ are essentially mutually equal and the pressures which prevail in portions 14a″ and 14b″.
By this means the rotor 20 will be efficiently balanced in the radial direction which entails for several advantages as indicated above.
In use of the valve, the axle 22 of the rotor 20 is connected to a, preferably, controllable braking means (not shown). Preferably the braking means is an electrical generator which is controllable in regard of the output power. By controlling the braking force applied to the rotor 20, it is possible to control the differential pressure or the flow rate between the upstream portion 14a′, 14b′ and the downstream portion 14a″, 14b″ of the chambers 14a, 14b and thereby between the inlet port 15 and the outlet port 16 of the valve.
A second embodiment of the valve according to the invention is illustrated in
This valve comprises a stator 110 and a rotor 120. The stator 110 comprises a stator core 112 and axially opposing end walls 113. The stator core 112 and the end walls 113 enclose an interior space 114. The stator core is generally cylindrical and exhibits a number of matrixes of radial through holes which forms inlet 112a and outlet 112b openings to and from the interior space 114.
Two inlet channels 131, 132 and two outlet channels 133, 134 are arranged radially outside the stator core 112. Each inlet channel 131, 132 is generally annularly shaped and comprises a radially protruding inlet port 131a, 132a. Each outlet channel 133, 134 is also generally annularly shaped and comprises a radially protruding outlet port 133a, 134a. The inlet channels 131, 132 and the outlet channels 133, 134 are formed of essentially identical parts and are arranged alternately one after the other along the axial direction of the stator core 112. As indicated in
In
The rotor 120 arranged in the interior space 114 comprises a rotor core 121 which is fixed to an axle 122. Alternatively, the rotor core may be formed integrally as one piece with the axle. The rotor 120 further comprises nineteen vanes 123 which are arranged in radial slots 124 of the rotor core 121. See
The vanes are urged towards the extracted position by means of e.g. a spring member (not shown) which is arranged in each slot, 124, radially inwards of the respective vane 123. Upon rotation of the rotor, the radial displacement of the vanes 123 is caused by the urging spring member and the contact between the outer edge of the vane 123 and the interior surface of the stator core 112.
As seen in
The valve shown in
Fluid provided to inlet port 131a is transported into chamber 114a and 114c by means of inlet channel 131, communication openings 131b, 131c and inlet openings 112a′, 112a″. In chambers 114a, 114c the pressure of the fluid acts on the active area of the extended vanes 123c and drives the rotor to rotation in the clockwise direction as seen in
Fluid provided to inlet port 132a is, in a corresponding manner, conveyed into and from the chambers 114b, 114d to thereby contribute to driving the rotor 120 to rotation. In use, the axle 122 is connected to an electric generator which may be controlled with regard to its braking power to thereby create any desired differential pressure or flow rate between the inlet ports 131a, 132a and the outlet ports 133a, 134a. The rotor 120 of the valve shown in
Comparative calculations of the efficiency at a previously known valve and a valve according to the present invention has been carried out. Except the differences in balancing of the rotor both valves are essentially equal and comprises a rotor with an active rotor length of approx. 300 mm.
At the previously know valve, a clearance of 2 mm between the rotor and the stator is needed for compensating for the deflection of the unbalanced rotor. This clearance results in a leakage opening of approx. 300 mm×2 mm=600 mm2 between the high pressure side and low pressure side at each vane.
Calculations have been carried out for such a known valve when driven at a differential pressure of 5 bar, where the fluid pressure upstream of the device is 6 bar and downstream 1 bar. These calculations show that if the valve is driven with an input water flow of 80 litres per second, then the internal leakage from the high pressure side to the low pressure side of the rotor is approximately 19 litres per second. Hence, the internal leakage amounts to as much as approx. 24% of the total water flow.
At the valve according to the invention it has proven to be sufficient to arrange a clearance of approx. 0.1 mm between the rotor and the stator. At the valve according to the invention a total leakage opening of approx. 300 mm×0.1 mm×2=60 mm2 prevails. When calculations corresponding to the prior art example above is carried out the following enhanced results appear. With a differential pressure of 5 bar at an upstream water pressure of 6 bar and a downstream pressure of 1 bar and with an input water flow of 80 litres per second, it has proven that the internal leakage is reduced to 1.9 litres per second. Hence the internal leakage is only approx. 2.4% of the total water flow.
The power efficiency of the valve, e.g. when the valve is connected to an electrical generator for generating electrical power, is inversely proportional to the internal leakage of the valve. Hence, when a valve according to the invention is used to replace a previously known valve under the conditions as set out in the examples above, the power efficiency is increased by approximately (100−2.4)/(100−24)=128%.
The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims. For example a rotor having pivotal or hinged vanes may readily be arranged in a stator of the type illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 12168237.1 | May 2012 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/060014 | 5/15/2013 | WO | 00 |
